Nikolas Blevins, MD

All Publications

Prevalence of Radiographic Cochlear-Facial Nerve Dehiscence. Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology Song, Y., Alyono, J. C., Bartholomew, R. A., Vaisbuch, Y., Corrales, C. E., Blevins, N. H. 2018
Abstract

OBJECTIVE: To determine the prevalence of radiographic cochlear-facial nerve dehiscence (CFD).STUDY DESIGN: Retrospective radiological study.SETTING: Two tertiary-referral centers.PATIENTS: Two hundred six temporal-bone computed tomography (CT) scans (405 total ears) of otology/neurotology patients from two academic institutions between the years 2014 and 2017.INTERVENTION: Diagnostic.MAIN OUTCOME MEASURES: The cochlear-facial nerve partition width (CFPW) was measured on coronal CT sections and defined as the shortest distance between the cochlear basal turn and facial nerve (FN) labyrinthine segment. We used logistics regression analyses to determine positive predictors for radiographic evidence of CFD.RESULTS: The overall prevalence of radiographic CFD was 5.4% (22/406 ears). 9.2% of patients (19/206) had CFD. Of these 19 patients, only one patient had mixed hearing loss that could not be explained by any other vestibular or auditory etiology. Three out of 206 patients had dehiscence in both ears (1.4%). The average CFPW was 0.6 ± 0.2 mm, and fallopian canal width was 1.1 ± 0.02 mm (n = 405). Older age, use of traditional CT scans, and thinner CT slice thickness were significant predictors for radiographic CFD.CONCLUSIONS: The radiographic prevalence of CFD is higher than what is reported in histologic studies, and may over-estimate the true prevalence of CFD. The clinician should keep this in mind when considering this as potential cause for third-window symptoms.

View details for DOI 10.1097/MAO.0000000000002015

View details for PubMedID 30289844
Long-Term Hearing Outcomes Following Stereotactic Radiosurgery in Vestibular Schwannoma Patients-A Retrospective Cohort Study. Neurosurgery Santa Maria, P. L., Shi, Y., Gurgel, R. K., Corrales, C. E., Soltys, S. G., Santa Maria, C., Murray, K., Chang, S. D., Blevins, N. H., Gibbs, I. C., Jackler, R. K. 2018
Abstract

BACKGROUND: An understanding of the hearing outcomes is needed for treatment counseling for patients with vestibular schwannomas (VS).OBJECTIVE: To determine long-term hearing results following stereotactic radiosurgery (SRS) for VS and identify any influential variables.METHODS: Tertiary hospital retrospective cohort.RESULTS: There were 579 tumors (576 patients) treated with SRS. Eighty-two percent (473) of tumors had ≥1 yr and 59% (344 ≥3 yr follow-up. In the 244 tumor ears, with measurable hearing before SRS who were followed ≥1 yr, 14% (31) had improved hearing, 13% (29) unchanged hearing, and 74% (158) had worsened hearing. In 175 patients with ≥3 yr follow-up and who had measurable hearing pretreatment, 6% (11 ears) improved hearing, 31% (54 ears) unchanged hearing, and 63% (110 ears) had worsened hearing. Patients with tumors with larger target volumes (P=0.040) and with neurofibromatosis type 2 (NF2; P=0.017) were associated with poorer hearing (P=0.040). Patients with word recognition scores (WRS) of 50% or poorer had tumors with a larger volume (P=0.0002), larger linear size (P=0.032), and NF2 (P=0.045). Traditionally reported hearing outcomes using the Gardner Robertson maintenance of PTA ≤50 db or WRS ≥50% were 48% at 3 yr, which overestimates hearing outcomes compared to the above reporting standards.CONCLUSION: Hearing declines over time in VS treated with SRS in a high proportion of cases. The frequency and magnitude of long-term hearing decline following SRS argues against prophylactic radiation for small tumors in hearing ears with undetermined growth behavior.

View details for DOI 10.1093/neuros/nyy407

View details for PubMedID 30247723
In reference to Evidence against the mucosal traction theory in cholesteatoma. The Laryngoscope Jackler, R. K., Santa Maria, P. L., Blevins, N. H. 2018
View details for DOI 10.1002/lary.27097

View details for PubMedID 29392724
Early experience with a patient-specific virtual surgical simulation for rehearsal of endoscopic skull-base surgery INTERNATIONAL FORUM OF ALLERGY & RHINOLOGY Won, T., Hwang, P., Lim, J., Cho, S., Paek, S., Losorelli, S., Vaisbuch, Y., Chan, S., Salisbury, K., Blevins, N. H. 2018; 8 (1): 54–63
Abstract

With the help of contemporary computer technology it is possible to create a virtual surgical environment (VSE) for training. This article describes a patient-specific virtual rhinologic surgical simulation platform that supports rehearsal of endoscopic skull-base surgery. We also share our early experience with select cases.A rhinologic VSE was developed, featuring a highly efficient direct 3-dimensional (3D) volume renderer with simultaneous stereoscopic feedback during surgical manipulation of the virtual anatomy, as well as high-fidelity haptic feedback. We conducted a retrospective analysis on 10 patients who underwent various forms of sinus and ventral skull-base surgery to assess the ability of the rhinologic VSE to replicate actual intraoperative findings.In all 10 cases, the simulation experience was realistic enough to perform dissections in a similar manner as in the actual surgery. Excellent correlation was found in terms of surgical exposure, anatomical features, and the locations of pathology.The current rhinologic VSE shows sufficient realism to allow patient-specific surgical rehearsal of the sinus and ventral skull base. Further validation studies are needed to assess the benefits of performing patient-specific rehearsal.

View details for DOI 10.1002/alr.22037

View details for Web of Science ID 000419640200009

View details for PubMedID 29105367
Nasoseptal flap closure of the eustachian tube for recalcitrant cerebrospinal fluid rhinorrhea. The Laryngoscope Patel, V. S., Choby, G. W., Thamboo, A., Blevins, N. H., Hwang, P. H. 2017
View details for DOI 10.1002/lary.26988

View details for PubMedID 29152752
Electrode Array Displacement into the Fallopian Canal in Revisions of Long-standing Cochlear Implants OTOLOGY & NEUROTOLOGY Alyono, J., Locketz, G., Corrales, C. E., Blevins, N. H. 2017; 38 (5): 667-671
Abstract

To describe extracochlear extension of revision cochlear implant arrays into the Fallopian canal.Two adult patients with extension of revision cochlear implant arrays into the Fallopian canal.Computed tomography (CT), selective deactivation of non-functional electrodes.Facial nerve function, facial nerve stimulation, cochlear implant electrode position, radiography, functional hearing.Two patients presented with failure of their long-standing cochlear implants (CIs). One patient with presumed postviral hearing loss presented with declining function and increasing facial stimulation from an implant placed 30 years previous. A second with postmeningitic hearing loss presented with a draining mastoid fistula from an implant placed 7 years before. Both patients were reimplanted with minimal insertion resistance via the established electrode tract, yet demonstrated facial nerve stimulation during intraoperative telemetry and on device activation. Postoperative CTs of each patient showed exit of the electrode from the cochlea into the tympanic or labyrinthine Fallopian canal. Both patients can use their devices effectively with selective electrode deactivation.Our cases illustrate the potential association of long-standing electrodes with otic capsule changes, allowing extracochlear malposition of subsequent arrays. This can occur despite apparently uneventful reinsertion of a flexible array without undue force. Previously reported histopathology confirms the potential for a reactive osteitis from arrays that may contribute to this phenomenon. Intraoperative facial stimulation with neural telemetry testing can raise suspicion of a malpositioned array involving the Fallopian canal. Such cases can be effectively managed with selective deactivation of malpositioned electrode contacts.

View details for DOI 10.1097/MAO.0000000000001376

View details for Web of Science ID 000401025800007

View details for PubMedID 28353620
Anatomy-Specific Virtual Reality Simulation in Temporal Bone Dissection: Perceived Utility and Impact on Surgeon Confidence. Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery Locketz, G. D., Lui, J. T., Chan, S., Salisbury, K., Dort, J. C., Youngblood, P., Blevins, N. H. 2017; 156 (6): 1142-1149
Abstract

Objective To evaluate the effect of anatomy-specific virtual reality (VR) surgical rehearsal on surgeon confidence and temporal bone dissection performance. Study Design Prospective pre- and poststudy of a novel virtual surgical rehearsal platform. Setting Academic otolaryngology-head and neck surgery residency training programs. Subjects and Methods Sixteen otolaryngology-head and neck surgery residents from 2 North American training institutions were recruited. Surveys were administered to assess subjects' baseline confidence in performing 12 subtasks of cortical mastoidectomy with facial recess. A cadaver temporal bone was randomly assigned to each subject. Cadaver specimens were scanned with a clinical computed tomography protocol, allowing the creation of anatomy-specific models for use in a VR surgical rehearsal platform. Subjects then rehearsed a virtual mastoidectomy on data sets derived from their specimens. Surgical confidence surveys were administered again. Subjects then dissected assigned cadaver specimens, which were blindly graded with a modified Welling scale. A final survey assessed the perceived utility of rehearsal on dissection performance. Results Of 16 subjects, 14 (87.5%) reported a significant increase in overall confidence after conducting an anatomy-specific VR rehearsal. A significant correlation existed between perceived utility of rehearsal and confidence improvement. The effect of rehearsal on confidence was dependent on trainee experience and the inherent difficulty of the surgical subtask. Postrehearsal confidence correlated strongly with graded dissection performance. Subjects rated anatomy-specific rehearsal as having a moderate to high contribution to their dissection performance. Conclusion Anatomy-specific virtual rehearsal improves surgeon confidence in performing mastoid dissection, dependent on surgeon experience and task difficulty. The subjective confidence gained through rehearsal correlates positively with subsequent objective dissection performance.

View details for DOI 10.1177/0194599817691474

View details for PubMedID 28322125
First results of a novel adjustable-length ossicular reconstruction prosthesis in temporal bones. Laryngoscope Gottlieb, P. K., Li, X., Monfared, A., Blevins, N., Puria, S. 2016; 126 (11): 2559-2564
Abstract

The performance of an ossicular replacement prosthesis (ORP) is influenced by its alignment and appropriate tension between the tympanic membrane and the stapes footplate. A novel ORP with a flexible element that potentially allows for length adjustment in situ is presented and tested for acoustic performance.Laser Doppler vibrometry in fresh human cadaveric temporal bones was used to test the acoustic performance of the adjustable ORP relative to standard prostheses used for ossiculoplasty.The three-dimensional (3D) velocity of the stapes posterior crus was measured in the 0.2- to 20-kHz range using a Polytec CLV-3D laser Doppler vibrometer. The middle ear cavity was accessed through a facial recess approach. After measuring the normal response, the incus was removed and stapes velocity was measured in the disarticulated case, then after insertion of the new prosthesis, a conventional prosthesis (Kurz BELL Dusseldorf type), and a sculpted autologous incus prosthesis in each temporal bone. The 3D stapes velocity transfer function (SVTF) was calculated for each case and compared.The novel ORP design restored stapes velocity to within 6 dB (on average) of the intact response. No significant differences in 3D-SVTF were found between the new, conventional, or autologous ORPs.The inclusion of an in situ adjustable element into the ORP design did not adversely affect its acoustic performance. The adjustable element may increase the ease of achieving optimal ORP placement, especially through a facial recess approach.NA Laryngoscope, 126:2559-2564, 2016.

View details for DOI 10.1002/lary.25901

View details for PubMedID 26972795

View details for PubMedCentralID PMC5018907
Fusion of Computed Tomography and PROPELLER Diffusion-Weighted Magnetic Resonance Imaging for the Detection and Localization of Middle Ear Cholesteatoma. JAMA otolaryngology-- head & neck surgery Locketz, G. D., Li, P. M., Fischbein, N. J., Holdsworth, S. J., Blevins, N. H. 2016; 142 (10): 947-953
Abstract

A method to optimize imaging of cholesteatoma by combining the strengths of available modalities will improve diagnostic accuracy and help to target treatment.To assess whether fusing Periodically Rotated Overlapping Parallel Lines With Enhanced Reconstruction (PROPELLER) diffusion-weighted magnetic resonance imaging (DW-MRI) with corresponding temporal bone computed tomography (CT) images could increase cholesteatoma diagnostic and localization accuracy across 6 distinct anatomical regions of the temporal bone.Case series and preliminary technology evaluation of adults with preoperative temporal bone CT and PROPELLER DW-MRI scans who underwent surgery for clinically suggested cholesteatoma at a tertiary academic hospital. When cholesteatoma was encountered surgically, the precise location was recorded in a diagram of the middle ear and mastoid. For each patient, the 3 image data sets (CT, PROPELLER DW-MRI, and CT-MRI fusion) were reviewed in random order for the presence or absence of cholesteatoma by an investigator blinded to operative findings.If cholesteatoma was deemed present on review of each imaging modality, the location of the lesion was mapped presumptively. Image analysis was then compared with surgical findings.Twelve adults (5 women and 7 men; median [range] age, 45.5 [19-77] years) were included. The use of CT-MRI fusion had greater diagnostic sensitivity (0.88 vs 0.75), positive predictive value (0.88 vs 0.86), and negative predictive value (0.75 vs 0.60) than PROPELLER DW-MRI alone. Image fusion also showed increased overall localization accuracy when stratified across 6 distinct anatomical regions of the temporal bone (localization sensitivity and specificity, 0.76 and 0.98 for CT-MRI fusion vs 0.58 and 0.98 for PROPELLER DW-MRI). For PROPELLER DW-MRI, there were 15 true-positive, 45 true-negative, 1 false-positive, and 11 false-negative results; overall accuracy was 0.83. For CT-MRI fusion, there were 20 true-positive, 45 true-negative, 1 false-positive, and 6 false-negative results; overall accuracy was 0.90.The poor anatomical spatial resolution of DW-MRI makes precise localization of cholesteatoma within the middle ear and mastoid a diagnostic challenge. This study suggests that the bony anatomic detail obtained via CT coupled with the excellent sensitivity and specificity of PROPELLER DW-MRI for cholesteatoma can improve both preoperative identification and localization of disease over DW-MRI alone.

View details for DOI 10.1001/jamaoto.2016.1663

View details for PubMedID 27414044
Facial Nerve Outcome and Tumor Control Rate as a Function of Degree of Resection in Treatment of Large Acoustic Neuromas: Preliminary Report of the Acoustic Neuroma Subtotal Resection Study (ANSRS) NEUROSURGERY Monfared, A., Corrales, C. E., Theodosopoulos, P. V., Blevins, N. H., Oghalai, J. S., Selesnick, S. H., Lee, H., Gurgel, R. K., Hansen, M. R., Nelson, R. F., Gantz, B. J., Kutz, J. W., Isaacson, B., Roland, P. S., Amdur, R., Jackler, R. K. 2016; 79 (2): 194-200
Abstract

Patients with large vestibular schwannomas are at high risk of poor facial nerve (cranial nerve VII [CNVII]) function after surgery. Subtotal resection potentially offers better outcome, but may lead to higher tumor regrowth.To assess long-term CNVII function and tumor regrowth in patients with large vestibular schwannomas.Prospective multicenter nonrandomized cohort study of patients with vestibular schwannoma ≥2.5 cm who received gross total resection, near total resection, or subtotal resection. Patients received radiation if tumor remnant showed signs of regrowth.Seventy-three patients had adequate follow-up with mean tumor diameter of 3.33 cm. Twelve received gross total resection, 22 near total resection, and 39 subtotal resection. Fourteen (21%) remnant tumors continued to grow, of which 11 received radiation, 1 had repeat surgery, and 2 no treatment. Four of the postradiation remnants (36%) required surgical salvage. Tumor regrowth was related to non-cystic nature, larger residual tumor, and subtotal resection. Regrowth was 3 times as likely with subtotal resection compared to gross total resection and near total resection. Good CNVII function was achieved in 67% immediately and 81% at 1-year. Better immediate nerve function was associated with smaller preoperative tumor size and percentage of tumor left behind on magnetic resonance image. Degree of resection defined by surgeon and preoperative tumor size showed weak trend toward better late CNVII function.Likelihood of tumor regrowth was 3 times higher in subtotal resection compared to gross total resection and near total resection groups. Rate of radiation control of growing remnants was suboptimal. Better immediate but not late CNVII outcome was associated with smaller tumors and larger tumor remnants.CNVII, cranial nerve VIIGTR, gross total resectionHB, House-BrackmannMRI, magnetic resonance imageNTR, near total resectionSTR, subtotal resection.

View details for DOI 10.1227/NEU.0000000000001162

View details for Web of Science ID 000382335100019

View details for PubMedID 26645964
In response to a new theory on the pathogenesis of acquired cholesteatoma: Mucosal traction. Laryngoscope Jackler, R. K., Maria, P. L., Varsak, Y. K., Blevins, N. H., Nguyen, A. 2016; 126 (3): E131-?
View details for DOI 10.1002/lary.25654

View details for PubMedID 26372503
In reference to A new theory on the pathogenesis of acquired cholesteatoma: Mucosal traction. Laryngoscope Jackler, R. K., Santa Maria, P. L., Varsak, Y. K., Blevins, N. H., Nguyen, A. 2016; 126 (1): E50-?
View details for DOI 10.1002/lary.25542

View details for PubMedID 26267761
High-fidelity haptic and visual rendering for patient-specific simulation of temporal bone surgery COMPUTER ASSISTED SURGERY Chan, S., Li, P., Locketz, G., Salisbury, K., Blevins, N. H. 2016; 21 (1): 85-101
Abstract

Medical imaging techniques provide a wealth of information for surgical preparation, but it is still often the case that surgeons are examining three-dimensional pre-operative image data as a series of two-dimensional images. With recent advances in visual computing and interactive technologies, there is much opportunity to provide surgeons an ability to actively manipulate and interpret digital image data in a surgically meaningful way. This article describes the design and initial evaluation of a virtual surgical environment that supports patient-specific simulation of temporal bone surgery using pre-operative medical image data. Computational methods are presented that enable six degree-of-freedom haptic feedback during manipulation, and that simulate virtual dissection according to the mechanical principles of orthogonal cutting and abrasive wear. A highly efficient direct volume renderer simultaneously provides high-fidelity visual feedback during surgical manipulation of the virtual anatomy. The resulting virtual surgical environment was assessed by evaluating its ability to replicate findings in the operating room, using pre-operative imaging of the same patient. Correspondences between surgical exposure, anatomical features, and the locations of pathology were readily observed when comparing intra-operative video with the simulation, indicating the predictive ability of the virtual surgical environment.

View details for DOI 10.1080/24699322.2016.1189966

View details for Web of Science ID 000390847000011

View details for PubMedID 27973948
Pediatric Semicircular Canal Dehiscence: Radiographic and Histologic Prevalence, With Clinical Correlation OTOLOGY & NEUROTOLOGY Meiklejohn, D. A., Corrales, C. E., Boldt, B. M., Sharon, J. D., Yeom, K. W., Carey, J. P., Blevins, N. H. 2015; 36 (8): 1383-1389
Abstract

To determine the prevalence of radiographic and histologic superior semicircular canal dehiscence (SSCD) and posterior semicircular canal dehiscence (PSCD) and associated changes in temporal bone thickness in children aged 0 to 7 years.Retrospective chart review and histopathologic review of cadaveric bone specimens.Two tertiary referral centers.Children younger than 7 years who underwent high-resolution computed tomography scan including the temporal bones between 1998 and 2013 and temporal bones harvested from children younger than 7 years.Two hundred twenty-eight computed tomography studies and 58 temporal bone specimens were reviewed. Available patient demographics were tabulated.Prevalence of SSCD and PSCD and bone thickness over semicircular canals, with comparison across age groups. Clinical data were extracted for patients with radiographic dehiscence.Prevalence by ear of SSCD was 11.9%, 4.9%, 2.8%, and 0% and of PSCD was 16.7%, 2.4%, 1.4%, and 0% in children aged less than 6 months, 6 to 11 months, 12 to 35 months, and 3 to 7 years, respectively. SSCD was statistically more common before 1 year of age and PSCD before 6 months of age. Bone thickness overlying both the SSC and the PSC increased with age. Radiographic PSC bone was significantly thicker than SSC bone in patients older than 12 months. No dehiscences were found in the histologic specimens.Radiographic dehiscence of the canals is common in the first 6 months of life, with thin bone seen histologically. Prevalence decreases with increasing age as the bone overlying the canals increases in thickness.

View details for DOI 10.1097/MAO.0000000000000811

View details for Web of Science ID 000360488000015
A new theory on the pathogenesis of acquired cholesteatoma: Mucosal traction. Laryngoscope Jackler, R. K., Santa Maria, P. L., Varsak, Y. K., Nguyen, A., Blevins, N. H. 2015; 125: S1-S14
Abstract

Although the migration of its squamous outer surface of the tympanic membrane has been well characterized, there is a paucity of data available concerning the migratory behavior of its medial mucosal surface. Existing theories of primary acquired cholesteatoma pathogenesis do not adequately explain the observed characteristics of the disease. We propose a new hypothesis, based upon a conjecture that mucosal membrane interactions are the driving force in cholesteatoma.A retrospective chart review and a prospective observational cohort study in rats.After developing the new theory, it was tested through both clinical and experimental observations. To evaluate whether impairment of middle ear mucociliary migration would influence cholesteatoma formation, a retrospective chart review evaluating cholesteatoma occurrence in a sizable population of patients with either primary ciliary dyskinesia (PCD) or cystic fibrosis (CF) was performed. To study mucosal migration on the medial aspect of the tympanic membrane, ink tattoos were monitored over time in a rat model.No cholesteatomas were identified in either PCD patients (470) or in CF patients (1,910). In the rat model, mucosa of the posterior pars tensa migrated toward the posterior superior quadrant, whereas the mucosa of the anterior pars tensa migrated radially toward the annulus.Mucosal coupling with traction generated by interaction of migrating opposing surfaces provides the first comprehensive theory that explains the observed characteristics of primary acquired cholesteatoma. The somewhat counterintuitive hypothesis that cholesteatoma is fundamentally a mucosal disease has numerous therapeutic implications.4. Laryngoscope, 125:S1-S14, 2015.

View details for DOI 10.1002/lary.25261

View details for PubMedID 26013635
A new theory on the pathogenesis of acquired cholesteatoma: Mucosal traction LARYNGOSCOPE Jackler, R. K., Maria, P. L., Varsak, Y. K., Anh Nguyen, A., Blevins, N. H. 2015; 125: S1-S14
Abstract

Although the migration of its squamous outer surface of the tympanic membrane has been well characterized, there is a paucity of data available concerning the migratory behavior of its medial mucosal surface. Existing theories of primary acquired cholesteatoma pathogenesis do not adequately explain the observed characteristics of the disease. We propose a new hypothesis, based upon a conjecture that mucosal membrane interactions are the driving force in cholesteatoma.A retrospective chart review and a prospective observational cohort study in rats.After developing the new theory, it was tested through both clinical and experimental observations. To evaluate whether impairment of middle ear mucociliary migration would influence cholesteatoma formation, a retrospective chart review evaluating cholesteatoma occurrence in a sizable population of patients with either primary ciliary dyskinesia (PCD) or cystic fibrosis (CF) was performed. To study mucosal migration on the medial aspect of the tympanic membrane, ink tattoos were monitored over time in a rat model.No cholesteatomas were identified in either PCD patients (470) or in CF patients (1,910). In the rat model, mucosa of the posterior pars tensa migrated toward the posterior superior quadrant, whereas the mucosa of the anterior pars tensa migrated radially toward the annulus.Mucosal coupling with traction generated by interaction of migrating opposing surfaces provides the first comprehensive theory that explains the observed characteristics of primary acquired cholesteatoma. The somewhat counterintuitive hypothesis that cholesteatoma is fundamentally a mucosal disease has numerous therapeutic implications.4. Laryngoscope, 125:S1-S14, 2015.

View details for DOI 10.1002/lary.25261

View details for Web of Science ID 000358374200001
Development and Characterization of Chemical Cochleostomy in the Guinea Pig OTOLARYNGOLOGY-HEAD AND NECK SURGERY Alyono, J. C., Corrales, C. E., Huth, M. E., Blevins, N. H., Ricci, A. J. 2015; 152 (6): 1113-1118
Abstract

Creation of an atraumatic, hearing-preservation cochleostomy is integral to the future of minimally invasive inner ear surgery. The goal of this study was to develop and characterize a novel chemical approach to cochleostomy.Prospective animal study.Laboratory.Experimental animal study in which phosphoric acid gel (PAG) was used to decalcify the otic capsule in 25 Hartley guinea pigs. Five animals in each of 5 surgical groups were studied: (1) mechanically opening the auditory bulla alone, (2) PAG thinning of the basal turn otic capsule, leaving endosteum covered by a layer of bone, (3) micro-pick manual cochleostomy, (4) PAG chemical cochleostomy, exposing the endosteum, and (5) combined PAG/micro-pick cochleostomy, with initial chemical thinning and subsequent manual removal of the last osseous layer. Preoperative and postoperative auditory brainstem responses and otoacoustic emissions were obtained at 2, 6, 10, and 16 kHz. Hematoxylin and eosin-stained paraffin sections were compared.Surgical and histologic findings confirmed that application of PAG provided reproducible local bone removal, and cochlear access was enabled. Statistically significant auditory threshold shifts were observed at 10 kHz (P = .048) and 16 kHz (P = .0013) following cochleostomy using PAG alone (group 4) and at 16 kHz using manual cochleostomy (group 3) (P = .028). No statistically significant, postoperative auditory threshold shifts were observed in the other groups, including PAG thinning with manual completion cochleostomy (group 5).Hearing preservation cochleostomy can be performed in an animal model using a novel technique of thinning cochlear bone with PAG and manually completing cochleostomy.

View details for DOI 10.1177/0194599815573703

View details for Web of Science ID 000355692300025

View details for PubMedID 25779472
A case of stereotactic radiation in skull base solitary fibrous tumor: more harm than good? Journal of neurological surgery reports Santa Maria, P. L., Abuzeid, W. M., Nayak, J. V., Chang, S. D., Blevins, N. H. 2014; 75 (2): e214-6
Abstract

Objective Due to its location, total resection of a skull base solitary fibrous tumor (SFT) can lead to morbidity with injury to lower cranial nerves, and a decision must be made between subtotal resection with possible stereotactic radiotherapy or total resection with cranial nerve morbidity. We report the long-term outcomes and review the literature of a case of stereotactic radiation in SFT to provide evidence for making this decision. Design A retrospective case review. Setting An academic tertiary referral center. Results We present a case with > 10 years follow-up of radiation following skull base SFT, initially misdiagnosed as schwannoma, where radiotherapy did not improve recurrence or metastatic behavior and led to complications during subsequent surgical resection. Conclusions SFT often masquerades as schwannoma, especially in the skull base. Careful immunohistochemistry, including CD34 expression, is critical to the diagnosis and management. This case highlights that total tumor resection of SFT remains the gold standard of treatment. Stereotactic radiation is not recommended in the management of skull base SFT.

View details for DOI 10.1055/s-0034-1387196

View details for PubMedID 25485216

View details for PubMedCentralID PMC4242816
Hearing Preservation Surgery for Cochlear Implantation: A Meta-analysis OTOLOGY & NEUROTOLOGY Maria, P. L., Gluth, M. B., Yuan, Y., Atlas, M. D., Blevins, N. H. 2014; 35 (10): E256-E269
Abstract

To examine the results of hearing preservation in cochlear implantation surgery to identify surgical technical factors, electrode array design factors, and steroid usage, which predicts greater low-frequency hearing preservation.A thorough search of Medline and Pubmed of English studies from January 1, 1995, to January 1, 2013, was performed using the key words "electric and acoustic hearing" or "hybrid cochlear implant" or "EAS cochlear implant" or "partial deafness cochlear implant" or "bimodal hearing cochlear implant" or "hearing preservation cochlear implant."The meta-analysis was conducted according to the PRISMA statement. Only articles in English were included. Studies were included if hearing preservation was the primary end point. A final number of 24 studies met the inclusion criteria.Patient populations were analyzed as intention to treat. Data were extracted from raw audiograms where possible. Data were excluded if not all explanatory variables were present or if variable values were ambiguous.The weighted least-squares regression method was used to determine the predictive power of each explanatory variable across all studies.In this meta-analysis, the following are associated with better hearing preservation: cochleostomy over the round window approach, posterior tympanotomy over the suprameatal approach, a slow electrode array insertion technique over insertion of less than 30 seconds, a soft tissue cochleostomy seal over a fibrin glue only seal and the use of postoperative systemic steroids. Longer electrode arrays, topical steroid use, and lubricant use for electrode array insertion did not give an advantage.

View details for Web of Science ID 000345157200001
Comprehensive Measures of Sound Exposures in Cinemas Using Smart Phones EAR AND HEARING Huth, M. E., Popelka, G. R., Blevins, N. H. 2014; 35 (6): 680-686
Abstract

Sensorineural hearing loss from sound overexposure has a considerable prevalence. Identification of sound hazards is crucial, as prevention, due to a lack of definitive therapies, is the sole alternative to hearing aids. One subjectively loud, yet little studied, potential sound hazard is movie theaters. This study uses smart phones to evaluate their applicability as a widely available, validated sound pressure level (SPL) meter. Therefore, this study measures sound levels in movie theaters to determine whether sound levels exceed safe occupational noise exposure limits and whether sound levels in movie theaters differ as a function of movie, movie theater, presentation time, and seat location within the theater.Six smart phones with an SPL meter software application were calibrated with a precision SPL meter and validated as an SPL meter. Additionally, three different smart phone generations were measured in comparison to an integrating SPL meter. Two different movies, an action movie and a children's movie, were measured six times each in 10 different venues (n = 117). To maximize representativeness, movies were selected focusing on large release productions with probable high attendance. Movie theaters were selected in the San Francisco, CA, area based on whether they screened both chosen movies and to represent the largest variety of theater proprietors. Measurements were analyzed in regard to differences between theaters, location within the theater, movie, as well as presentation time and day as indirect indicator of film attendance.The smart phone measurements demonstrated high accuracy and reliability. Overall, sound levels in movie theaters do not exceed safe exposure limits by occupational standards. Sound levels vary significantly across theaters and demonstrated statistically significant higher sound levels and exposures in the action movie compared to the children's movie. Sound levels decrease with distance from the screen. However, no influence on time of day or day of the week as indirect indicator of film attendance could be found.Calibrated smart phones with an appropriate software application as used in this study can be utilized as a validated SPL meter. Because of the wide availability, smart phones in combination with the software application can provide high quantity recreational sound exposure measurements, which can facilitate the identification of potential noise hazards. Sound levels in movie theaters decrease with distance to the screen, but do not exceed safe occupational noise exposure limits. Additionally, there are significant differences in sound levels across movie theaters and movies, but not in presentation time.

View details for Web of Science ID 000346489500017

View details for PubMedID 25075764
Facial nerve schwannomas presenting as occluding external auditory canal masses: a therapeutic dilemma. Otology & neurotology Alyono, J. C., Corrales, C. E., Gurgel, R. K., Blevins, N., Jackler, R. K. 2014; 35 (7): 1284-1289
Abstract

To present a series of patients with facial nerve schwannomas (FNSs) presenting as occluding external auditory canal (EAC) masses.Retrospective case series.Four patients were identified with mastoid segment FNSs occluding the EAC. Three patients presented with conductive hearing loss (CHL), and the fourth presented with facial paralysis, later developing CHL.One patient underwent conservative debulking, removing the EAC component only. Two patients were managed nonoperatively with periodic cleaning of entrapped keratin. The fourth patient received radiation therapy.Facial nerve function, canal cholesteatoma formation, and hearing.Among the patients managed with serial cleaning of entrapped keratin, one maintained normal facial function and one worsened to House-Brackmann II/VI. Facial function worsened to House-Brackmann II/VI in the patient who underwent surgical debulking. The fourth patient, who received radiation, developed complete facial paralysis. All patients accumulated keratin medial to the tumor, and all had CHL.When evaluating an EAC tumor, it is important to obtain imaging before biopsy because biopsy of a schwannoma can result in paralysis. EAC occlusion by a schwannoma presents a challenging management issue, particularly when cholesteatoma forms between the tumor and the tympanic membrane. The primary goal is maintaining normal facial function as long as possible and avoiding secondary ear canal complications. The presence of canal occlusion limits the choice of stereotactic radiation because this leads to a month-long period of tumor swelling and cutaneous sloughing. Resection and grafting are indicated when substantial facial weakness or twitch develops.

View details for DOI 10.1097/MAO.0000000000000398

View details for PubMedID 24853246
Imaging for evaluation of cholesteatoma: current concepts and future directions. Current opinion in otolaryngology & head and neck surgery Corrales, C. E., Blevins, N. H. 2013; 21 (5): 461-467
Abstract

To examine the rationale and utility of imaging in patients with known or suspected cholesteatoma, with emphasis on high-resolution computed tomography (HRCT) and diffusion-weighted MRI (DW-MRI).The initial diagnosis of cholesteatoma is largely based on patient history and clinical findings. HRCT scan can be a useful adjunct to define the presence of pathologic soft tissue in the temporal bone, and the extent of bony erosion, and inform the otologic surgeon about expected findings at the time of surgery. Although MRI has not traditionally been used in the evaluation of cholesteatoma given its poor resolution of bone anatomy, recent advances in DW-MRI sequences allow for high sensitivity and specificity in identifying the presence of cholesteatoma. More specifically, non-echo-planar DW-MRI is superior in the detection of residual or recurrent cholesteatoma compared to delayed-contrast MRI and echo-planar DW-MRI.HRCT and DW-MRI offer complementary anatomic information that can be used effectively in the management of cholesteatoma. DW-MRI imaging has proven to be a reliable method for detecting residual or recurrent cholesteatomas down to 3 mm in size, and allows radiologic differentiation between cholesteatoma and other soft tissue. As more centers implement DW-MRI imaging for detecting residual or recurrent cholesteatoma, there will likely be less need for second-look surgery, thereby potentially decreasing associated morbidity and surgical costs.

View details for DOI 10.1097/MOO.0b013e328364b473

View details for PubMedID 23880648
Evaluating the utility of non-echo-planar diffusion-weighted imaging in the preoperative evaluation of cholesteatoma: A meta-analysis. Laryngoscope Li, P. M., Linos, E., Gurgel, R. K., Fischbein, N. J., Blevins, N. H. 2013; 123 (5): 1247-1250
Abstract

To describe the accuracy of non-echo-planar diffusion-weighted magnetic resonance imaging (DW MRI) in identifying middle ear cholesteatoma.A meta-analysis of the published literature.A systematic review of the literature was performed to identify studies in which patients suspected of having middle ear cholesteatoma underwent DW MRI scans prior to surgery. A meta-analysis of the included studies was performed.Ten published articles (342 patients) met inclusion criteria. Cholesteatoma was confirmed in 234 patients, of which 204 were detected by DW MRI (true positives) and 30 were not (false negatives). One hundred eight patients did not have cholesteatoma on surgical examination, and of these 100 were correctly identified by MRI (true negatives) whereas eight were not (false positives). The overall sensitivity of DW MRI in detecting cholesteatoma was 0.94 (confidence interval, 0.80-0.98) and specificity 0.94 (confidence interval, 0.85-0.98). DW MRI sequences could not reliably detect cholesteatomas under 3 mm in size.Non-echo-planar DW MRI is highly sensitive and specific in identifying middle ear cholesteatoma. DW MRI may help to stratify patients into groups of who would benefit from early second-look surgery and those who could be closely observed.2a.

View details for DOI 10.1002/lary.23759

View details for PubMedID 23023958
Virtual Reality Simulation in Neurosurgery: Technologies and Evolution NEUROSURGERY Chan, S., Conti, F., Salisbury, K., Blevins, N. H. 2013; 72: A154-A164
Abstract

Neurosurgeons are faced with the challenge of learning, planning, and performing increasingly complex surgical procedures in which there is little room for error. With improvements in computational power and advances in visual and haptic display technologies, virtual surgical environments can now offer potential benefits for surgical training, planning, and rehearsal in a safe, simulated setting. This article introduces the various classes of surgical simulators and their respective purposes through a brief survey of representative simulation systems in the context of neurosurgery. Many technical challenges currently limit the application of virtual surgical environments. Although we cannot yet expect a digital patient to be indistinguishable from reality, new developments in computational methods and related technology bring us closer every day. We recognize that the design and implementation of an immersive virtual reality surgical simulator require expert knowledge from many disciplines. This article highlights a selection of recent developments in research areas related to virtual reality simulation, including anatomic modeling, computer graphics and visualization, haptics, and physics simulation, and discusses their implication for the simulation of neurosurgery.

View details for DOI 10.1227/NEU.0b013e3182750d26

View details for Web of Science ID 000315848100020
Deformable Haptic Rendering for Volumetric Medical Image Data IEEE World Haptics Conference (WHC) Chan, S., Blevins, N. H., Salisbury, K. IEEE. 2013: 73–78
View details for Web of Science ID 000325187400013
Virtual reality simulation in neurosurgery: technologies and evolution. Neurosurgery Chan, S., Conti, F., Salisbury, K., Blevins, N. H. 2013; 72: 154-164
Abstract

Neurosurgeons are faced with the challenge of learning, planning, and performing increasingly complex surgical procedures in which there is little room for error. With improvements in computational power and advances in visual and haptic display technologies, virtual surgical environments can now offer potential benefits for surgical training, planning, and rehearsal in a safe, simulated setting. This article introduces the various classes of surgical simulators and their respective purposes through a brief survey of representative simulation systems in the context of neurosurgery. Many technical challenges currently limit the application of virtual surgical environments. Although we cannot yet expect a digital patient to be indistinguishable from reality, new developments in computational methods and related technology bring us closer every day. We recognize that the design and implementation of an immersive virtual reality surgical simulator require expert knowledge from many disciplines. This article highlights a selection of recent developments in research areas related to virtual reality simulation, including anatomic modeling, computer graphics and visualization, haptics, and physics simulation, and discusses their implication for the simulation of neurosurgery.

View details for DOI 10.1227/NEU.0b013e3182750d26

View details for PubMedID 23254804
The effect of haptic degrees of freedom on task performance in virtual surgical environments. Studies in health technology and informatics Forsslund, J., Chan, S., Selesnick, J., Salisbury, K., Silva, R. G., Blevins, N. H. 2013; 184: 129-135
Abstract

Force and touch feedback, or haptics, can play a significant role in the realism of virtual reality surgical simulation. While it is accepted that simulators providing haptic feedback often outperform those that do not, little is known about the degree of haptic fidelity required to achieve simulation objectives. This article evaluates the effect that employing haptic rendering with different degrees of freedom (DOF) has on task performance in a virtual environment. Results show that 6-DOF haptic rendering significantly improves task performance over 3-DOF haptic rendering, even if computed torques are not displayed to the user. No significant difference could be observed between under-actuated (force only) and fully-actuated 6-DOF feedback in two surgically-motivated tasks.

View details for PubMedID 23400144
High-Fidelity, Inexpensive Surgical Middle Ear Simulator OTOLOGY & NEUROTOLOGY Monfared, A., Mitteramskogler, G., Gruber, S., Salisbury, J. K., Stampfl, J., Blevins, N. H. 2012; 33 (9): 1573-1577
Abstract

A high-fidelity, inexpensive middle ear simulator could be created to enhance surgical training that would be rated as having high face validity by experts.With rapid prototyping using additive manufacturing technology (AMT), one can create high-resolution 3-dimensional replicas of the middle ear at low cost and high fidelity. Such a simulator could be of great benefit for surgical training, particularly in light of new resident training guidelines.AMT was used to create surgical middle ear simulator (SMS) with 2 different materials simulating bone and soft tissue. The simulator is composed of an outer box with dimensions of an average adult external auditory canal without scutum and an inner cartridge based on an otosclerosis model. The simulator was then rated by otology experts in terms of face validity and fidelity as well as their opinion on the usefulness of such a device.Eighteen otologists from 6 tertiary academic centers rated the simulator; 83.3% agreed or highly agreed that SMS has accurate dimensions and 66.6% that it has accurate tactile feedback. When asked if performance of stapedotomy with the SMS improves with practice, 46% agreed. As to whether practicing stapedotomy with the SMS translates to improvement with live surgery, 78% agreed with this statement. Experts' average rating of the components of SMS (of possible 5) was as follows: middle ear dimensions, 3.9; malleus, 3.7; incus, 3.6; stapes, 3.6; chorda tympani, 3.7; tensor tympani, 4.1; stapedius, 3.8; facial nerve, 3.7; and promontory, 3.5. Overall, 83% found SMS to be at least "very useful" in training of novices, particularly for junior and senior residents.Most experts found the SMS to be accurate, but there was a large discrepancy in rating of individual components. Most found it to be very useful for training of novice surgeons. With these results, we are encouraged to proceed with further refinements that will strengthen the SMS as a training tool for otologic surgery.

View details for DOI 10.1097/MAO.0b013e31826dbca5

View details for Web of Science ID 000311214500025

View details for PubMedID 23047262
Radiographic Evaluation of the Tegmen in Patients With Superior Semicircular Canal Dehiscence OTOLOGY & NEUROTOLOGY Nadaraja, G. S., Gurgel, R. K., Fischbein, N. J., Anglemyer, A., Monfared, A., Jackler, R. K., Blevins, N. H. 2012; 33 (7): 1245-1250
Abstract

To determine a radiographic association between superior semicircular canal dehiscence (SSCD) and tegmen dehiscence (TD).Retrospective case-control series.Tertiary referral center.Patients seen between 2003 and 2010 with radiographic SSCD were compared with cochlear implant recipient controls.The tegmen and superior semicircular canal were evaluated on computed tomographic temporal bone scans.If detected, the widest point of the SSCD was measured. The tegmen was graded on a 5-point scale. After analysis, a radiographic TD was defined as any single area of absent tegmen greater than 5 mm, multiple areas of absent tegmen, or evidence of meningocele. Age, sex, and body mass index were also noted.Thirty-eight patients with SSCD and 41 cochlear implant controls were identified. Seventy-six percent (29/38) of patients with unilateral or bilateral SSCD had a radiographic TD on at least 1 side compared with 22% (9/41) of the comparison group. Ninety-four percent (7/18) of patients with bilateral SSCD had a TD on at least 1 side. Patients with SSCD had a 10.2 times (p < 0.001) higher odds of having radiographic TD in either ear compared to the controls. Among patients with any SSCD, for every millimeter increase in the width of dehiscence, the relative risk for any TD increased more than 2-fold (odds ratio, 2.5; p = 0.019). Age, sex, and a body mass index greater than 30 did not confound the association between SSCD and TD.There is a strong radiologic association between SSCD and TD, suggesting a similar etiologic process. The tegmen should be carefully evaluated in patients with SSCD. We have also proposed a new system for radiographically grading the integrity of the tegmen.

View details for DOI 10.1097/MAO.0b013e3182634e27

View details for Web of Science ID 000308092200029

View details for PubMedID 22872173
Is It Valid to Calculate the 3-Kilohertz Threshold by Averaging 2 and 4 Kilohertz? OTOLARYNGOLOGY-HEAD AND NECK SURGERY Gurgel, R. K., Popelka, G. R., Oghalai, J. S., Blevins, N. H., Chang, K. W., Jackler, R. K. 2012; 147 (1): 102-104
Abstract

Many guidelines for reporting hearing results use the threshold at 3 kilohertz (kHz), a frequency not measured routinely. This study assessed the validity of estimating the missing 3-kHz threshold by averaging the measured thresholds at 2 and 4 kHz. The estimated threshold was compared to the measured threshold at 3 kHz individually and when used in the pure-tone average (PTA) of 0.5, 1, 2, and 3 kHz in audiometric data from 2170 patients. The difference between the estimated and measured thresholds for 3 kHz was within ± 5 dB in 72% of audiograms, ± 10 dB in 91%, and within ± 20 dB in 99% (correlation coefficient r = 0.965). The difference between the PTA threshold using the estimated threshold compared with using the measured threshold at 3 kHz was within ± 5 dB in 99% of audiograms (r = 0.997). The estimated threshold accurately approximates the measured threshold at 3 kHz, especially when incorporated into the PTA.

View details for DOI 10.1177/0194599812437156

View details for Web of Science ID 000314267600018

View details for PubMedID 22301102
Superior semicircular canal dehiscence diagnosed after failed stapedotomy for conductive hearing loss AMERICAN JOURNAL OF OTOLARYNGOLOGY Li, P. M., Bergeron, C., Monfared, A., Agrawal, S., Blevins, N. H. 2011; 32 (5): 441-444
View details for DOI 10.1016/j.amjoto.2010.07.016

View details for Web of Science ID 000294704200017

View details for PubMedID 20888070
Tinnitus suppression by low-rate electric stimulation and its electrophysiological mechanisms HEARING RESEARCH Zeng, F., Tang, Q., Dimitrijevic, A., Starr, A., Larky, J., Blevins, N. H. 2011; 277 (1-2): 61-66
Abstract

Tinnitus is a phantom sensation of sound in the absence of external stimulation. However, external stimulation, particularly electric stimulation via a cochlear implant, has been shown to suppress tinnitus. Different from traditional methods of delivering speech sounds or high-rate (>2000 Hz) stimulation, the present study found a unique unilaterally-deafened cochlear implant subject whose tinnitus was completely suppressed by a low-rate (<100 Hz) stimulus, delivered at a level softer than tinnitus to the apical part of the cochlea. Taking advantage of this novel finding, the present study compared both event-related and spontaneous cortical activities in the same subject between the tinnitus-present and tinnitus-suppressed states. Compared with the results obtained in the tinnitus-present state, the low-rate stimulus reduced cortical N100 potentials while increasing the spontaneous alpha power in the auditory cortex. These results are consistent with previous neurophysiological studies employing subjects with and without tinnitus and shed light on both tinnitus mechanism and treatment.

View details for DOI 10.1016/j.heares.2011.03.010

View details for Web of Science ID 000293726600008

View details for PubMedID 21447376

View details for PubMedCentralID PMC3137665
Dural arteriovenous fistula following translabyrinthine resection of cerebellopontine angle tumors: report of two cases. Skull base reports Li, P. M., Fischbein, N. J., Do, H. M., Blevins, N. H. 2011; 1 (1): 51-58
Abstract

We describe two cases of dural arteriovenous fistula (DAVF) developing in a delayed fashion after translabyrinthine resection of cerebellopontine angle tumors. Two patients in an academic tertiary referral center, a 46-year-old woman and a 67-year-old man, underwent translabyrinthine resection of a 2-cm left vestibular schwannoma and a 4-cm left petrous meningioma, respectively. Both patients subsequently developed DAVF, and in each case the diagnosis was delayed despite serial imaging follow-up. In one patient, cerebrospinal fluid diversion before DAVF was identified as the cause of her intracranial hypertension; the other patient was essentially asymptomatic but with a high risk of hemorrhage due to progression of cortical venous drainage. Endovascular treatment was effective but required multiple sessions due to residual or recurrent fistulas. Dural arteriovenous fistula is a rare complication of translabyrinthine skull base surgery. Diagnosis requires a high index of clinical suspicion and an understanding of subtle imaging findings that may be present on follow-up studies performed for tumor surveillance. Failure to recognize this complication may lead to misguided interventions for treatment of hydrocephalus and other complications, as well as ongoing risks related to venous hypertension and intracranial hemorrhage. As this condition is generally curable with neurointerventional and/or surgical methods, timely diagnosis and treatment are essential.

View details for DOI 10.1055/s-0031-1275634

View details for PubMedID 23984203

View details for PubMedCentralID PMC3743590
CT Angiography as a Screening Tool for Dural Arteriovenous Fistula in Patients with Pulsatile Tinnitus: Feasibility and Test Characteristics AMERICAN JOURNAL OF NEURORADIOLOGY Narvid, J., Do, H. M., Blevins, N. H., Fischbein, N. J. 2011; 32 (3): 446-453
Abstract

The diagnosis of intracranial DAVF with noninvasive cross-sectional imaging such as CTA is challenging. We sought to determine the sensitivity and specificity of CTA compared with cerebral angiography for DAVF in patients presenting with PT.Following approval of the institutional review board, we reviewed all patients who underwent CTA for PT from 2004 to 2009 and collected clinical and imaging data. Seven patients with PT and proved DAVF and 7 age- and sex-matched control patients with PT but no DAVF composed the study group. CTA images were blindly interpreted by 2 experienced neuroradiologists for the presence of 5 variables: asymmetric arterial feeding vessels, "shaggy" appearance of a dural venous sinus, transcalvarial venous channels, asymmetric venous collaterals, and abnormal size and number of cortical veins. Asymmetric attenuation of jugular veins was additionally assessed.The presence of arterial feeders showed good test characteristics for screening, with a sensitivity of 86% (95% CI, 42-99) and a specificity of 100% (95% CI, 52-100). A shaggy sinus or tentorium was highly specific: sensitivity of 42% (95% CI, 11-79) and specificity of 100% (95% CI, 56-100). The presence of transcalvarial venous channels demonstrated a poor sensitivity of 29% (95% CI, 5-70) but a high specificity 86% (95% CI, 42-99). CT attenuation of the jugular veins showed statistically significant asymmetry in the DAVF group versus the control group (P < .05).CTA can be used to screen for DAVF in patients with PT. The presence of asymmetrically visible and enlarged arterial feeding vessels has a high sensitivity and specificity for the diagnosis of DAVF.

View details for DOI 10.3174/ajnr.A2328

View details for Web of Science ID 000288639800007

View details for PubMedID 21402614
A virtual surgical environment for rehearsal of tympanomastoidectomy. Studies in health technology and informatics Chan, S., Li, P., Lee, D. H., Salisbury, J. K., Blevins, N. H. 2011; 163: 112-118
Abstract

This article presents a virtual surgical environment whose purpose is to assist the surgeon in preparation for individual cases. The system constructs interactive anatomical models from patient-specific, multi-modal preoperative image data, and incorporates new methods for visually and haptically rendering the volumetric data. Evaluation of the system's ability to replicate temporal bone dissections for tympanomastoidectomy, using intraoperative video of the same patients as guides, showed strong correlations between virtual and intraoperative anatomy. The result is a portable and cost-effective tool that may prove highly beneficial for the purposes of surgical planning and rehearsal.

View details for PubMedID 21335772

View details for PubMedCentralID PMC3434876
Curing hearing loss: Patient expectations, health care practitioners, and basic science 19th Annual ASHA/NIH/NIDCD Research Symposium on Neural Regeneration and Communication Processes Oshima, K., Suchert, S., Blevins, N. H., Heller, S. ELSEVIER SCIENCE INC. 2010: 311–18
Abstract

Millions of patients are debilitated by hearing loss, mainly caused by degeneration of sensory hair cells in the cochlea. The underlying reasons for hair cell loss are highly diverse, ranging from genetic disposition, drug side effects, traumatic noise exposure, to the effects of aging. Whereas modern hearing aids offer some relief of the symptoms of mild hearing loss, the only viable option for patients suffering from profound hearing loss is the cochlear implant. Despite their successes, hearing aids and cochlear implants are not perfect. Particularly frequency discrimination and performance in noisy environments and general efficacy of the devises vary among individual patients. The advent of regenerative medicine, the publicity of stem cells and gene therapy, and recent scientific achievements in inner ear cell regeneration have generated an emerging spirit of optimism among scientists, health care practitioners, and patients. In this review, we place the different points of view of these three groups in perspective with the goal of providing an assessment of patient expectations, health care reality, and potential future treatment options for hearing disorders.(1) Readers will be encouraged to put themselves in the position of a hearing impaired patient or family member of a hearing impaired person. (2) Readers will be able to explain why diagnosis of the underlying pathology of hearing loss is difficult. (3) Readers will be able to list the main directions of current research aimed to cure hearing loss. (4) Readers will be able to understand the different viewpoints of patients and their relatives, health care providers, and scientists with respect to finding novel treatments for hearing loss.

View details for DOI 10.1016/j.jcomdis.2010.04.002

View details for Web of Science ID 000279199700006

View details for PubMedID 20434163

View details for PubMedCentralID PMC2885475
Reconstruction and exploration of virtual middle-ear models derived from micro-CT datasets 5th International Symposium on Middle Ear Mechanics in Research and Otology (MEMRO 2009) Lee, D. H., Chan, S., Salisbury, C., Kim, N., Salisbury, K., Puria, S., Blevins, N. H. ELSEVIER SCIENCE BV. 2010: 198–203
Abstract

Middle-ear anatomy is integrally linked to both its normal function and its response to disease processes. Micro-CT imaging provides an opportunity to capture high-resolution anatomical data in a relatively quick and non-destructive manner. However, to optimally extract functionally relevant details, an intuitive means of reconstructing and interacting with these data is needed.A micro-CT scanner was used to obtain high-resolution scans of freshly explanted human temporal bones. An advanced volume renderer was adapted to enable real-time reconstruction, display, and manipulation of these volumetric datasets. A custom-designed user interface provided for semi-automated threshold segmentation. A 6-degrees-of-freedom navigation device was designed and fabricated to enable exploration of the 3D space in a manner intuitive to those comfortable with the use of a surgical microscope. Standard haptic devices were also incorporated to assist in navigation and exploration.Our visualization workstation could be adapted to allow for the effective exploration of middle-ear micro-CT datasets. Functionally significant anatomical details could be recognized and objective data could be extracted.We have developed an intuitive, rapid, and effective means of exploring otological micro-CT datasets. This system may provide a foundation for additional work based on middle-ear anatomical data.

View details for DOI 10.1016/j.heares.2010.01.007

View details for Web of Science ID 000278583700025

View details for PubMedID 20100558
Preliminary Evaluation of a Novel Bone-Conduction Device for Single-Sided Deafness OTOLOGY & NEUROTOLOGY Popelka, G. R., Derebery, J., Blevins, N. H., Murray, M., Moore, B. C., Sweetow, R. W., Wu, B., Katsis, M. 2010; 31 (3): 492-497
Abstract

A new intraoral bone-conduction device has advantages over existing bone-conduction devices for reducing the auditory deficits associated with single-sided deafness (SSD).Existing bone-conduction devices effectively mitigate auditory deficits from single-sided deafness but have suboptimal microphone locations, limited frequency range, and/or require invasive surgery. A new device has been designed to improve microphone placement (in the ear canal of the deaf ear), provide a wider frequency range, and eliminate surgery by delivering bone-conduction signals to the teeth via a removable oral appliance.Forces applied by the oral appliance were compared with forces typically experienced by the teeth from normal functions such as mastication or from other appliances. Tooth surface changes were measured on extracted teeth, and transducer temperature was measured under typical use conditions. Dynamic operating range, including gain, bandwidth, and maximum output limits, were determined from uncomfortable loudness levels and vibrotactile thresholds, and speech recognition scores were measured using normal-hearing subjects. Auditory performance in noise (Hearing in Noise Test) was measured in a limited sample of SSD subjects. Overall comfort, ease of insertion, and removal and visibility of the oral appliance in comparison with traditional hearing aids were measured using a rating scale.The oral appliance produces forces that are far below those experienced by the teeth from normal functions or conventional dental appliances. The bone-conduction signal level can be adjusted to prevent tactile perception yet provide sufficient gain and output at frequencies from 250 to 12,000 Hz. The device does not damage tooth surfaces nor produce heat, can be inserted and removed easily, and is as comfortable to wear as traditional hearing aids. The new microphone location has advantages for reducing the auditory deficits caused by SSD, including the potential to provide spatial cues introduced by reflections from the pinna, compared with microphone locations for existing devices.A new approach for SSD has been proposed that optimizes microphone location and delivers sound by bone conduction through a removable oral appliance. Measures in the laboratory using normal-hearing subjects indicate that the device provides useful gain and output for SSD patients, is comfortable, does not seem to have detrimental effects on oral function or oral health, and has several advantages over existing devices. Specifically, microphone placement is optimized for reducing the auditory deficit caused by SSD, frequency bandwidth is much greater, and the system does not require surgical placement. Auditory performance in a small sample of SSD subjects indicated a substantial advantage compared with not wearing the device. Future studies will involve performance measures on SSD patients wearing the device for longer periods.

View details for DOI 10.1097/MAO.0b013e3181be6741

View details for Web of Science ID 000276555200019

View details for PubMedID 19816229
Cyberknife Radiotherapy for Vestibular Schwannoma OTOLARYNGOLOGIC CLINICS OF NORTH AMERICA Sakamoto, G. T., Blevins, N., Gibbs, I. C. 2009; 42 (4): 665-?
Abstract

Stereotactic radiosurgery is a well-established treatment modality for vestibular schwannoma. Initial reports using single-stage radiosurgery have demonstrated excellent tumor control rates. Many patients now elect to undergo radiosurgery given the potential for tumor control while avoiding the morbidity associated with microsurgical resection. In attempt to improve hearing preservation rates of single-state radiosurgery, staged frame-based radiotherapy using a 12-hour interfraction interval was used at the authors' institution and has shown a hearing preservation rate of 77% at 2 years of follow-up. With the arrival of the Cyberknife, a frameless, image-guided radiotherapy system, staged stereotactic radiotherapy for vestibular schwannoma became more practical. This article outlines the rationale and treatment protocols developed at Stanford University (California) and reports the authors' initial experience using the Cyberknife to treat vestibular schwannoma.

View details for DOI 10.1016/j.otc.2009.04.006

View details for Web of Science ID 000270502100007

View details for PubMedID 19751871
Integration of patient-specific paranasal sinus computed tomographic data into a virtual surgical environment 54th Annual Fall Meeting of the American-Rhinologic-Society Parikh, S. S., Chan, S., Agrawal, S. K., Hwang, P. H., Salisbury, C. M., Rafii, B. Y., Varma, G., Salisbury, K. J., Blevins, N. H. OCEAN SIDE PUBLICATIONS INC. 2009: 442–47
Abstract

The advent of both high-resolution computed tomographic (CT) imaging and minimally invasive endoscopic techniques has led to revolutionary advances in sinus surgery. However, the rhinologist is left to make the conceptual jump between static cross-sectional images and the anatomy encountered intraoperatively. A three-dimensional (3D) visuo-haptic representation of the patient's anatomy may allow for enhanced preoperative planning and rehearsal, with the goal of improving outcomes, decreasing complications, and enhancing technical skills.We developed a novel method of automatically constructing 3D visuo-haptic models of patients' anatomy from preoperative CT scans for placement in a virtual surgical environment (VSE). State-of-the-art techniques were used to create a high-fidelity representation of salient bone and soft tissue anatomy and to enable manipulation of the virtual patient in a surgically meaningful manner. A modified haptic interface device drives a virtual endoscope that mimics the surgical configuration.The creation and manipulation of sinus anatomy from CT data appeared to provide a relevant means of exploring patient-specific anatomy. Unlike more traditional methods of interacting with multiplanar imaging data, our VSE provides the potential for a more intuitive experience that can replicate the views and access expected at surgery. The inclusion of tactile (haptic) feedback provides an additional dimension of realism.The incorporation of patient-specific clinical CT data into a virtual surgical environment holds the potential to offer the surgeon a novel means to prepare for rhinologic procedures and offer training to residents. An automated pathway for segmentation, reconstruction, and an intuitive interface for manipulation may enable rehearsal of planned procedures.

View details for DOI 10.2500/ajra.2009.23.3335

View details for Web of Science ID 000268797300016

View details for PubMedID 19671264
Sensorineural hearing loss in patients with inflammatory bowel disease AMERICAN JOURNAL OF OTOLARYNGOLOGY Karmody, C. S., Valdez, T. A., Desai, U., Blevins, N. H. 2009; 30 (3): 166-170
Abstract

The study aimed to discuss the association between sensorineural hearing loss (SNHL) and inflammatory bowel disease (IBD).We reviewed cases of patients with known IBD seen in an otolaryngology practice with documentation of all otologic data including age of onset, family history of otologic problems, exposure to noise, audiometric findings, and so on.Of 38 patients with a history of IBD, 22 had documented SNHL. Nineteen of these had no other identifiable etiology for their inner ear dysfunction. Fourteen of these patients had a diagnosis of ulcerative colitis and 5 had Crohn disease. Sixteen patients had bilateral SNHL, and 3 patients had unilateral SNHL. Only one patient had a lasting response of SNHL to medical treatment.This review suggests that SNHL is an extraintestinal association of IBD. As IBD is considered to be a local or systemic immunopathy, the associated SNHL might also be an expression of systemic immune dysfunction.

View details for DOI 10.1016/j.amjoto.2008.04.009

View details for Web of Science ID 000266175400006

View details for PubMedID 19410121
Intraoperative staining of tympanoplasty grafts: A technique to facilitate graft placement OTOLARYNGOLOGY-HEAD AND NECK SURGERY Talas, D., Nguyen-Huynh, A., Blevins, N. H. 2008; 138 (5): 682-683
View details for DOI 10.1016/j.otohns.2008.01.019

View details for Web of Science ID 000255434700025

View details for PubMedID 18439479
Tympanic Membrane Collagen Fibers: A Key to High-Frequency Sound Conduction 110th Annual Meeting of the American-Academy-of-Otolaryngology-Head-and-Neck-Surgery-Foundation O'Connor, K. N., Tam, M., Blevins, N. H., Puria, S. LIPPINCOTT WILLIAMS & WILKINS. 2008: 483–90
Abstract

To investigate the significance of tympanic membrane collagen fiber layers in high frequency sound transmission.Human cadaver temporal bone study.Laser Doppler vibrometry was used to measure stapes footplate movement in response to acoustic stimulation. The tympanic membrane was altered by creating a series of slits and applying paper patches to isolate the effects of specifically oriented collagen fibers. Three groups of membrane alterations were evaluated: 1) circumferentially oriented slits involving each quadrant to primarily disrupt radial fibers, made sequentially within superior-anterior, inferior-anterior, inferior-posterior, and superior-posterior quadrants; 2) the same slits made in the reverse order; and 3) radially oriented slits from the umbo to the annulus to primarily disrupt circumferential fibers. For each group, measurements of the middle-ear cavity pressure, ear canal pressure, and stapes velocity were made each time the tympanic membrane was altered.Regardless of the order in which the circumferentially oriented slits were made, there was a consistent decrease in stapes velocity above 4 kHz for the third and fourth cuts compared to the control. The mean decrease in the range of 4 to 12.5 kHz was 11 dB for the third patched slit and 14 dB for the fourth patched slit (P < .01). Radially oriented slits appear to produce smaller effects.Radial collagen fibers in the tympanic membrane play an important role in the conduction of sound above 4 kHz.

View details for DOI 10.1097/MLG.0b013e31815b0d9f

View details for Web of Science ID 000260661800018

View details for PubMedID 18091335
Providing metrics and performance feedback in a surgical simulator COMPUTER AIDED SURGERY Sewell, C., Morris, D., Blevins, N. H., Dutta, S., Agrawal, S., Barbagli, F., Salisbury, K. 2008; 13 (2): 63-81
Abstract

One of the most important advantages of computer simulators for surgical training is the opportunity they afford for independent learning. However, if the simulator does not provide useful instructional feedback to the user, this advantage is significantly blunted by the need for an instructor to supervise and tutor the trainee while using the simulator. Thus, the incorporation of relevant, intuitive metrics is essential to the development of efficient simulators. Equally as important is the presentation of such metrics to the user in such a way so as to provide constructive feedback that facilitates independent learning and improvement. This paper presents a number of novel metrics for the automated evaluation of surgical technique. The general approach was to take criteria that are intuitive to surgeons and develop ways to quantify them in a simulator. Although many of the concepts behind these metrics have wide application throughout surgery, they have been implemented specifically in the context of a simulation of mastoidectomy. First, the visuohaptic simulator itself is described, followed by the details of a wide variety of metrics designed to assess the user's performance. We present mechanisms for presenting visualizations and other feedback based on these metrics during a virtual procedure. We further describe a novel performance evaluation console that displays metric-based information during an automated debriefing session. Finally, the results of several user studies are reported, providing some preliminary validation of the simulator, the metrics, and the feedback mechanisms. Several machine learning algorithms, including Hidden Markov Models and a Naïve Bayes Classifier, are applied to our simulator data to automatically differentiate users' expertise levels.

View details for DOI 10.1080/10929080801957712

View details for Web of Science ID 000256418000001

View details for PubMedID 18317956
Readout-segmented EPI for rapid high resolution diffusion imaging at 3T EUROPEAN JOURNAL OF RADIOLOGY Holdsworth, S. J., Skare, S., Newbould, R. D., Guzmann, R., Blevins, N. H., Bammer, R. 2008; 65 (1): 36-46
Abstract

Readout mosaic segmentation has been suggested as an alternative approach to EPI for high resolution diffusion-weighted imaging (DWI). In the readout-segmented EPI (RS-EPI) scheme, segments of k-space are acquired along the readout direction. This reduces geometric distortions due to the decrease in readout time. In this work, further distortion reduction is achieved by combining RS-EPI with parallel imaging (PI). The performance of the PI-accelerated RS-EPI scheme is assessed in volunteers and patients at 3T with respect to both standard EPI and PI-accelerated EPI. Peripherally cardiac gated and non-gated RS-EPI images are acquired to assess whether motion due to brain pulsation significantly degrades the image quality. Due to the low off-resonance of PI-driven RS-EPI, we also investigate if the eddy currents induced by the diffusion gradients are low enough to use the Stejskal-Tanner diffusion preparation instead of the twice-refocused eddy-current compensated diffusion preparation to reduce TE. It is shown that non-gated phase corrected DWI performs equally as well as gated acquisitions. PI-driven DW RS-EPI images with substantially less distortion compared with single-shot EPI are shown in patients-allowing the delineation of structures in the lower parts of the brain. A twice-refocused diffusion preparation was found necessary to avoid blurring in the DWI data. This paper shows that the RS-EPI scheme may be an important alternative sampling strategy to EPI to achieve high resolution T2-weighted and diffusion-weighted images.

View details for DOI 10.1016/j.ejrad.2007.09.016

View details for Web of Science ID 000253086400005

View details for PubMedID 17980534

View details for PubMedCentralID PMC3360876
Representing Fluid with Smoothed Particle Hydrodynamics in a Cranial Base Simulator 16th Conference on Medicine Meets Virtual Reality Liu, W., Sewell, C., Blevins, N., Salisbury, K., Bodin, K., Hjelte, N. I O S PRESS. 2008: 257–259
Abstract

We describe the implementation of irrigation and blood simulation using Smoothed Particle Hydrodynamics (SPH) in a cranial base surgical simulator. Graphical accuracy of virtual surgery is a significant goal for improving the realism and immersive experience of computerized training environments. For temporal bone micro-surgery fluids contribute not only to the visual integrity of the surgical field but provide relevant anatomic cues as well. The skill of 3-D sensory and navigation has become increasingly viable in surgery with the rising popularity of laparoscopic, catheter angiography and other minimally invasive approaches. The introduction of realistic simulated blood and irrigation enables the practice and coordination of two-handed microdissection techniques and the timing needed for safe bone removal and cautery.

View details for Web of Science ID 000272668400055

View details for PubMedID 18391299
Pediatric vestibulopathy and pseudovestibulopathy: differential diagnosis and management. Current opinion in otolaryngology & head and neck surgery Worden, B. F., Blevins, N. H. 2007; 15 (5): 304-309
Abstract

Evaluation of children with vestibular complaints may be challenging. The approach to these patients is often quite different than the approach to adults with similar complaints. This review will discuss the evaluation of pediatric vestibular disease with an emphasis on recent evidence in the literatureRecent evidence has elucidated the most common etiologies of vertigo in children, documented the utility and feasibility of objective diagnostic testing such as electronystagmography and vestibular evoked myogenic potentials in this population, and demonstrated the efficacy of new therapies such as rizatriptan for the treatment of migraine in children.An evidence-based approach to the evaluation of pediatric vestibular dysfunction may improve diagnostic yield and facilitate timely initiation of appropriate therapy.

View details for PubMedID 17823544
Evaluating Drilling and Suctioning Technique in a Mastoidectomy Simulator 15th Conference on Medicine Meets Virtual Reality Sewell, C., Morris, D., Blevins, N. H., Barbagli, F., Salisbury, K. I O S PRESS. 2007: 427–432
Abstract

This paper presents several new metrics related to bone removal and suctioning technique in the context of a mastoidectomy simulator. The expertise with which decisions as to which regions of bone to remove and which to leave intact is evaluated by building a Naïve Bayes classifier using training data from known experts and novices. Since the bone voxel mesh is very large, and many voxels are always either removed or not removed regardless of expertise, the mutual information was calculated for each voxel and only the most informative voxels used for the classifier. Leave-out-one cross validation showed a high correlation of calculated expert probabilities with scores assigned by instructors. Additional metrics described in this paper include those for assessing smoothness of drill strokes, proper drill burr selection, sufficiency of suctioning, two-handed tool coordination, and application of appropriate force and velocity magnitudes as functions of distance from critical structures.

View details for Web of Science ID 000270613800096

View details for PubMedID 17377317
The effect of virtual haptic training on real surgical drilling proficiency 2nd Joint EuroHaptics Conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems Sewell, C., Blevins, N. H., Peddamatham, S., Tan, H. Z., Morris, D., Salisbury, K. IEEE COMPUTER SOC. 2007: 601–603
View details for Web of Science ID 000246105200115
Validating Metrics for a Mastoidectomy Simulator 15th Conference on Medicine Meets Virtual Reality Sewell, C., Morris, D., Blevins, N. H., Agrawal, S., Dutta, S., Barbagli, F., Salisbury, K. I O S PRESS. 2007: 421–426
Abstract

One of the primary barriers to the acceptance of surgical simulators is that most simulators still require a significant amount of an instructing surgeon's time to evaluate and provide feedback to the students using them. Thus, an important area of research in this field is the development of metrics that can enable a simulator to be an essentially self-contained teaching tool, capable of identifying and explaining the user's weaknesses. However, it is essential that these metrics be validated in able to ensure that the evaluations provided by the "virtual instructor" match those that the real instructor would provide were he/she present. We have previously proposed a number of algorithms for providing automated feedback in the context of a mastoidectomy simulator. In this paper, we present the results of a user study in which we attempted to establish construct validity (with inter-rater reliability) for our simulator itself and to validate our metrics. Fifteen subjects (8 experts, 7 novices) were asked to perform two virtual mastoidectomies. Each virtual procedure was recorded, and two experienced instructing surgeons assigned global scores that were correlated with subjects' experience levels. We then validated our metrics by correlating the scores generated by our algorithms with the instructors' global ratings, as well as with metric-specific sub-scores assigned by one of the instructors.

View details for Web of Science ID 000270613800095

View details for PubMedID 17377316
Virtuosity with the mallet and gouge: The brilliant triumph of the "Modern" mastoid operation OTOLARYNGOLOGIC CLINICS OF NORTH AMERICA Sunder, S., Jackler, R. K., Blevins, N. H. 2006; 39 (6): 1191-?
Abstract

The development of mastoid surgery can be traced through the past 4 centuries. Once used as a means of evacuating a postauricular abscess, it has evolved to become a method for gaining entry into the middle ear for diagnostic purposes, to control chronic ear disease, or for otologic and neuro-otologic procedures. Earlier works led the way to the Wilde postauricular incision, which gave rise to Schwartze mastoidectomy. Stacke's technique of mastoidectomy was practiced for some time before Bondy, Heath, and Bryant introduced the modified radical mastoidectomy. By the 1930s, the mastoidectomy had evolved into a generally accepted otologic procedure. Endowed with a rich history, the future of mastoid surgery promises to be equally momentous.

View details for DOI 10.1016/j.otc.2006.08.014

View details for Web of Science ID 000242734700009

View details for PubMedID 17097441
Visuohaptic simulation of bone surgery for training and evaluation IEEE COMPUTER GRAPHICS AND APPLICATIONS Morris, D., Sewell, C., Barbagli, F., Salisbury, K., Blevins, N. H., Girod, S. 2006; 26 (6): 48-57
Abstract

Visual and haptic simulation of bone surgery can support and extend current surgical training techniques. The authors present a system for simulating surgeries involving bone manipulation, such as temporal bone surgery and mandibular surgery, and discuss the automatic computation of surgical performance metrics. Experimental results confirm the system's construct validity.

View details for Web of Science ID 000241568100008

View details for PubMedID 17120913
The challenges of revision skull base surgery OTOLARYNGOLOGIC CLINICS OF NORTH AMERICA Nguyen-Huynh, A., Blevins, N. H., Jackler, R. K. 2006; 39 (4): 783-?
Abstract

Because the skull base is an anatomically complex structure, skull base tumors can hide easily in the crevices that interconnect the intra- and extracranial spaces and intermingle with important neurovascular structures. Often, total surgical resection of these tumors is not possible, and even with postoperative adjuvant radiotherapy, some recurrences after treatment are inevitable. Early detection of recurrent skull base tumors requires clinical vigilance and periodic imaging studies. The management of recurrent skull base tumors presents many challenges beyond those associated with primary procedures. A multidisciplinary setting that includes modern microsurgery and stereotactic radiation therapy provides patients with optimal care.

View details for DOI 10.1016/j.otc.2006.04.006

View details for Web of Science ID 000240080900010

View details for PubMedID 16895785
Otologic manifestations of relapsing polychondritis - Review of literature and report of nine cases AURIS NASUS LARYNX Bachor, E., Blevins, N. H., Karmody, C., Kuehnel, T. 2006; 33 (2): 135-141
Abstract

Relapsing polychondritis (RP) is an episodic disease most likely of autoimmune etiology, characterized by recurrent inflammation of cartilaginous structures.Retrospective case study at two tertiary referral centers with presentation of nine patients with otologic involvement of RP, review of the spectrum of otologic disorders seen, and treatment.The clinical course of otologic manifestations of RP was highly variable and ranged from mild to moderate. In 6/9 patients there was an association with other autoimmune disorders. In addition to recurrent auricular chondritis, which was present in 8/9 patients, our patients had otitis externa, chronic myringitis, Eustachian tube dysfunction, conductive hearing loss, sensorineural hearing loss, and tinnitus. All patients had their diagnosis of RP made on the basis of their otologic involvement and the response to systemic corticosteroids.The diagnosis of RP is primarily clinical, but laboratory studies and biopsy may contribute as well. Once the diagnosis is suspected, the otolaryngologist should consider consultation with a rheumatologist to assist in the management of additional systemic manifestations.

View details for DOI 10.1016/j.anl.2005.11.020

View details for Web of Science ID 000237991200002

View details for PubMedID 16427754
Cochlear implantation in patients with neurofibromatosis Type 2 and bilateral vestibular schwannoma OTOLOGY & NEUROTOLOGY Lustig, L. R., Yeagle, J., Driscoll, C. L., Blevins, N., Francis, H., Niparko, J. K. 2006; 27 (4): 512-518
Abstract

To investigate the results of cochlear implantation in patients with neurofibromatosis Type 2 (NF2) and bilateral vestibular schwannoma.Retrospective case review.Three academic tertiary referral centers.Seven patients with NF2 and bilateral vestibular schwannoma who lost hearing in at least one ear after treatment of their tumor (surgery or radiation therapy).Cochlear implantation after treatment of their vestibular schwannoma.Postimplantation audiometric scores (pure-tone average thresholds, consonant-nucleus-consonant (CNC) words/phonemes, Central Institute for the Deaf (CID) sentences, Hearing in Noise Test (HINT) quiet/noise, and Monosyllable, Trochee, Spondee (MTS) recognition/category tests), patient satisfaction, and device use patterns.The average age at implantation was 40 years (range, 16-57 yr). Follow-up ranged from 6 to 88 months after implantation. Three patients were implanted with residual useful hearing in the contralateral ear, whereas four patients had no hearing in the contralateral ear. Hearing loss was due to surgical excision of tumor (n=5) or gamma-knife radiotherapy (n=2). Postactivation pure-tone average thresholds in the implanted ear ranged from 30 to 55 dB (average, 32.5 dB), although speech reception testing varied considerably among subjects. Despite this variability, all patients continue to use the device on a daily basis.In selected cases of deafness in patients with NF2 where there has been anatomic preservation of the auditory nerve after acoustic neuroma resection or radiation therapy, cochlear implantation may offer some improvement in communication skills, including the possibility of open-set speech communication in some patients. These results compare favorably to the auditory brainstem implant offering an alternative for hearing rehabilitation in patients with NF2.

View details for Web of Science ID 000237903000012

View details for PubMedID 16791043
In vivo Imaging of mammalian cochlear blood flow using fluorescence microendoscopy Annual Meeting of the American-Neurotology-Society Monfared, A., Blevins, N. H., Cheung, E. L., Jung, J. C., Popelka, G., Schnitzer, M. J. LIPPINCOTT WILLIAMS & WILKINS. 2006: 144–52
Abstract

We sought to develop techniques for visualizing cochlear blood flow in live mammalian subjects using fluorescence microendoscopy.Inner ear microcirculation appears to be intimately involved in cochlear function. Blood velocity measurements suggest that intense sounds can alter cochlear blood flow. Disruption of cochlear blood flow may be a significant cause of hearing impairment, including sudden sensorineural hearing loss. However, inability to image cochlear blood flow in a nondestructive manner has limited investigation of the role of inner ear microcirculation in hearing function. Present techniques for imaging cochlear microcirculation using intravital light microscopy involve extensive perturbations to cochlear structure, precluding application in human patients. The few previous endoscopy studies of the cochlea have suffered from optical resolution insufficient for visualizing cochlear microvasculature. Fluorescence microendoscopy is an emerging minimally invasive imaging modality that provides micron-scale resolution in tissues inaccessible to light microscopy. In this article, we describe the use of fluorescence microendoscopy in live guinea pigs to image capillary blood flow and movements of individual red blood cells within the basal turn of the cochlea.We anesthetized eight adult guinea pigs and accessed the inner ear through the mastoid bulla. After intravenous injection of fluorescein dye, we made a limited cochleostomy and introduced a compound doublet gradient refractive index endoscope probe 1 mm in diameter into the inner ear. We then imaged cochlear blood flow within individual vessels in an epifluorescence configuration using one-photon fluorescence microendoscopy.We observed single red blood cells passing through individual capillaries in several cochlear structures, including the round window membrane, spiral ligament, osseous spiral lamina, and basilar membrane. Blood flow velocities within inner ear capillaries varied widely, with observed speeds reaching up to approximately 500 microm/s.Fluorescence microendoscopy permits visualization of cochlear microcirculation with micron-scale optical resolution and determination of blood flow velocities through analysis of video sequences.

View details for Web of Science ID 000235346400003

View details for PubMedID 16436982
Achieving Proper Exposure in Surgical Simulation 14th Conference on Medicine Meets Virtual Reality Sewell, C., Morris, D., Blevins, N., Barbagli, F., Salisbury, K. I O S PRESS. 2006: 497–502
Abstract

One important technique common throughout surgery is achieving proper exposure of critical anatomic structures so that their shapes, which may vary somewhat among patients, can be confidently established and avoided. In this paper, we present an algorithm for determining which regions of selected structures are properly exposed in the context of a mastoidectomy simulation. Furthermore, our algorithm then finds and displays all other points along the surface of the structure that lie along a sufficiently short and straight path from an exposed portion such that their locations can be safely inferred. Finally, we present an algorithm for providing realistic visual cues about underlying structures with view-dependent shading of the bone.

View details for Web of Science ID 000269690200106

View details for PubMedID 16404107
Sensorineural hearing loss, early greying, and essential tremor: A new hereditary syndrome? NAPCRG Conference 2003 Karmody, C. S., Blevins, N. H., Lalwani, A. K. SAGE PUBLICATIONS LTD. 2005: 94–99
Abstract

To present a syndrome composed of sensorineural hearing loss, early greying of scalp hair, and adult-onset essential tremor.Retrospective chart review.Tertiary care academic hospital.Three individuals were seen with this triad, each with family members with similar features. Our patients are a 65-year-old man and two women in their 40s. Two noted hearing loss in adulthood, one as a child. All had complete greying in their 20s. The women developed essential tremor in their 20s, and the man in his 50s. All individuals have blue eyes without heterochromia. Additional evaluation failed to further categorize these patients. Each has two or more immediate family members with a combination of these findings. Molecular genetic testing suggests this is not a variant of Waardenburg syndrome.We believe this represents a previously unreported hereditary syndrome.This new syndrome should be considered in the context of other syndromes involving audition, pigmentation, and movement.

View details for DOI 10.1016/j.otohns.2005.03.017

View details for Web of Science ID 000230406600018

View details for PubMedID 16025060
Mid-frequency sensorineural hearing loss: aetiology and prognosis Meeting of the Eastern Section of the Triological-Society Shah, R. K., Blevins, N. H., Karmody, C. S. CAMBRIDGE UNIV PRESS. 2005: 529–33
Abstract

An audiometric finding of mid-frequency sensorineural hearing loss (MFSNHL), or a U-shaped pattern, is uncommon. The objective of this study is to investigate the aetiology and prognostic significance of MFSNHL.Tertiary academic referral centre-based retrospective case review and review of audiograms to determine the prevalence of this audiometric finding.Patients with a pure tone threshold average at 1, 2, and 4 kHz at least 10 dB greater than the average at 0.5 and 8 kHz were included in this study; 35 patients met these criteria. The mean age of the patients was 34.6 years old (range 4-71 years). Twelve patients (33 per cent) were under 18 years of age. Serial audiograms were obtained for 14 patients. The notes were reviewed for any pertinent otologic history, subsequent diagnoses, management and disease course.The prevalence of MFSNHL in this practice setting is less than 1 per cent. The average hearing threshold in the mid-frequencies was 44 dB, which was 17 dB and 20 dB lower than at 0.5 Hz and 8 kHz, respectively. The pure tone average (0.5, 1, 2 kHz) was 40 dB. Sixteen patients (44 per cent) required amplification. Of all patients, 22 had hereditary hearing loss, eight had idiopathic hearing loss, and five adults had vestibular schwannomas.MFSNHL is an infrequent audiometric finding. The great majority of these cases are of presumed hereditary or idiopathic aetiology, although 22 per cent of adults had vestibular schwannomas. This series presents the causes and prognosis of this audiometric pattern.

View details for Web of Science ID 000230515700005

View details for PubMedID 16175977
Quantifying Risky Behavior in Surgical Simulation 13th Conference on Medicine Meets Virtual Reality Sewell, C., Morris, D., Blevins, N., Barbagli, F., Salisbury, K. I O S PRESS. 2005: 451–457
Abstract

Evaluating a trainee's performance on a simulated procedure involves determining whether a specified objective was met while avoiding certain "injurious" actions that damage vulnerable structures. However, it is also important to teach the stylistic behaviors that minimize overall risk to the patient, even though these criteria may be more difficult to explicitly specify and detect. In this paper, we address the development of metrics that evaluate the risk in a trainee's behavior while performing a simulated mastoidectomy. Specifically, we measure the trainee's ability to maintain an appropriate field of view so as to avoid drilling bone that is hidden from view, as well as to consistently apply appropriate forces and velocities. Models of the maximum safe force and velocity magnitudes as functions of distances from key vulnerable structures are learned from model procedures performed by an expert surgeon on the simulator. In addition to quantitatively scoring the trainee's performance, these metrics allow for interactive 3D visualization of the performance by distinctive coloring of regions in which excessive forces or velocities were applied or insufficient visibility was maintained, enabling the trainee to pinpoint his/her mistakes and how to correct them. Although these risky behaviors relate to a mastoidectomy simulator, the objectives of maintaining visibility and applying safe forces and velocities are common in surgery, so it may be possible to extend much of this methodology to other procedures.

View details for Web of Science ID 000273828700090

View details for PubMedID 15718777
Transfacial recess ossicular reconstruction: Technique and early results Annual Meeting of the American-Otologic-Society Blevins, N. H. LIPPINCOTT WILLIAMS & WILKINS. 2004: 236–41
Abstract

The objective of this study was to present the technique of transfacial recess ossicular chain reconstruction (TFROCR) for potential use in selected patients with cholesteatoma.The author conducted a retrospective case review of all candidates for TFROCR between August 1998 and March 2003.A tertiary referral center.At first-stage tympanomastoidectomy, 22 ears (21 patients; 8 children and 13 adults) with cholesteatoma and ossicular discontinuity were identified as candidates for TFROCR. Seven patients had undergone previous tympanomastoid surgery.The first stage included canal wall up mastoidectomy with resection of disease, wide opening of the facial recess, cartilage graft tympanoplasty, and placement of silicone elastomer in the middle ear. Approximately 6 months later, patients underwent a second-stage postauricular procedure. Endoscopes were used to inspect the middle ear through the facial recess. When possible, TFROCR was then performed without elevating a tympanomeatal flap.Variations in anatomy, disease control, and hearing results were studied.Of the 22 candidate ears, 17 successfully underwent TFROCR, whereas 5 required traditional second-stage procedures with canal incisions. There were no surgical complications. Early hearing results are promising with an average air-bone gap of less than 20 dB. There have been no early failures from recurrent disease or prosthesis displacement.In carefully selected patients, TFROCR could be safe and effective for disease control and hearing restoration. It could provide for optimal prosthesis placement and almost immediate hearing improvement, avoiding the need for canal incisions, middle ear packing, and dry ear precautions. One must consider the potential risk of missing residual disease secondary to limited exposure.

View details for Web of Science ID 000221265700006

View details for PubMedID 15129098
A collaborative virtual environment for the simulation of temporal bone surgery 7th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI 2004) Morris, D., Sewell, C., Blevins, N., Barbagli, F., Salisbury, K. SPRINGER-VERLAG BERLIN. 2004: 319–327
View details for Web of Science ID 000224322400040
An event-driven framework for the simulation of complex surgical procedures 7th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI 2004) Sewell, C., Morris, D., Blevins, N., Barbagli, F., Salisbury, K. SPRINGER-VERLAG BERLIN. 2004: 346–354
View details for Web of Science ID 000224322400043
Otalgia OTOLARYNGOLOGIC CLINICS OF NORTH AMERICA Shah, R. K., Blevins, N. H. 2003; 36 (6): 1137-?
Abstract

The patient presenting with otalgia poses a diagnostic challenge for which orderly and diligent evaluation and management is needed. The etiology of otalgia can be either primary or referred, and a detailed history and physical examination with directed studies as indicated can elucidate the cause of the pain.

View details for DOI 10.1016/S0030-6665(03)00120-8

View details for Web of Science ID 000187581500010

View details for PubMedID 15025013
Current digital imaging for the otolaryngologist. Current opinion in otolaryngology & head and neck surgery Blevins, N. H., Lustig, L. R. 2003; 11 (3): 166-172
Abstract

Digital imaging has arrived as a standard tool for the otolaryngologist. There is no better evidence of this than the American Academy of Otolaryngology-Head and Neck Surgery moving to an all-digital format for its 2003 national meeting. No longer will 35-mm slide projectors be available for any presentations in the country's largest otolaryngology program. Also, all of the major journals in the field now accept or require digital files of illustrations and photographs. With this change in standard, the question is no longer if, or even when to incorporate digital imaging techniques, but how to do so most efficiently. This can be quite a challenge, given the ever-changing field of computer technology. This article is intended to introduce the fundamentals of digital imaging, and how this technology can best be integrated into an otolaryngology practice.

View details for PubMedID 12923357
External auditory canal duplication anomalies associated with congenital aural atresia JOURNAL OF LARYNGOLOGY AND OTOLOGY Blevins, N. H., Byahatti, S. V., Karmody, C. S. 2003; 117 (1): 32-38
Abstract

Maldevelopment of the first branchial cleft can produce a broad spectrum of anomalies in its derivative structure, the external auditory canal (EAC). Failure of the cleft to develop normally can result in either the absence of a normally patent EAC (atresia, or stenosis) or a duplication anomaly (cyst, sinus, or fistula). Despite their common origins, the coexistence of these anatomical abnormalities is quite unusual. We present four patients with both aural atresia and duplication anomalies of the EAC. Three patients had non-syndromic unilateral aural atresia and presented with periauricular lesions originating from the first branchial cleft. The other patient had a variant of Treacher Collins syndrome and presented with draining infra-auricular fistulae. The classification and management of first branchial cleft anomalies is reviewed in light of these cases. An understanding of the embryogenesis of the external ear is necessary to successfully recognize and treat this spectrum of deformities. A classification system is presented that encompasses the full spectrum of first cleft anomalies.

View details for Web of Science ID 000180534300005

View details for PubMedID 12590853
Potential use of diode laser soldering in middle ear reconstruction LASERS IN SURGERY AND MEDICINE Ditkoff, M., Blevins, N. H., Perrault, D., Shapshay, S. M. 2002; 31 (4): 242-246
Abstract

To assess the potential use of diode laser soldering to improve mechanical stability of middle ear reconstruction. The diode laser with a biological solder may offer benefits over traditional methods. We evaluated the strength of soldered bonds and a means to apply such a technique in the human middle ear.The strength of soldered junctions using fascia, cartilage, bone, and hydroxyappatite was evaluated in vitro. A diode laser (810-nm wavelength) and 50% albumin with 0.1% indocyanine green dye was used. Soldered bonds were compared to those obtained with adhesive alone. A fiberoptic delivery system was evaluated. Ten hydroxyappatite prostheses were soldered to the stapes in human cadaver temporal bones, and the force required to disrupt the bonds were measured.Statistically significant greater strength was obtained with soldering. Ossicular prostheses can be effectively secured to the stapes in a cadaver model.Soldering techniques show promise in middle ear reconstruction.

View details for DOI 10.1002/lsm.10091

View details for Web of Science ID 000178649100004

View details for PubMedID 12355568
Chronic myringitis: Prevalence, presentation, and natural history XXIInd Annual Meeting of the Pulitzer-Society Blevins, N. H., Karmody, C. S. LIPPINCOTT WILLIAMS & WILKINS. 2001: 3–10
Abstract

The aim of this study was to examine the clinical presentation and natural history of chronic myringitis (CM).Retrospective case review.Tertiary referral center.Chronic myringitis is defined as a loss of tympanic membrane epithelium for >1 month without disease within the tympanic cavity. Seven hundred fifty patient records were reviewed to determine the prevalence of CM in an academic otology practice. The records of 40 patients (45 ears) with CM seen between 1995 and 1999 inclusive were reviewed.The series was reviewed with attention to previous medical and otologic history, the nature and duration of symptoms, the physical findings, and management.The prevalence of CM was found to be -1% (approximately one fourth as common as cholesteatoma). Symptoms were often present for many years before the diagnosis of CM, with CM often mistaken for chronic otitis media. Sixty percent of patients had undergone previous otologic procedures. There did not appear to be an association between CM and systemic disease. Physical findings were varied, with granulation tissue and tympanic membrane perforations often occurring transiently. The clinical course of CM is typified by recurrent episodes of symptoms, often interspersed with long asymptomatic periods. A subset of CM can result in an acquired atresia. The most effective treatment appeared to be prolonged topical medications, surgery being reserved for only the most refractory cases.Chronic myringitis is often mistaken for chronic otitis media. Such confusion prolongs the initiation of appropriate management and sometimes leads to needless tympanomastoid surgery. The otologist should be aware of this clinical entity and its varied presentation.

View details for Web of Science ID 000167454000004

View details for PubMedID 11314712
Routine preoperative imaging in chronic ear surgery AMERICAN JOURNAL OF OTOLOGY Blevins, N. H., Carter, B. L. 1998; 19 (4): 527-535
Abstract

This article provides an overview of the practice and utility of preoperative radiologic studies in chronic otitis media (COM).A literature search of English language clinical and basic science publications was performed. Major otolaryngology texts were reviewed. Special attention was given to the clinical experience and recommendations of experienced otologic surgeons and radiologists regarding the use of radiologic studies in COM.There is no single accepted standard for the use of preoperative imaging in uncomplicated COM. Imaging studies, especially computed tomography (CT), can provide information regarding the nature and extent of disease, which may not be apparent on the basis of clinical findings alone. This information may impact the patient's operative management, especially in complex or revision cases. Each clinician must assess the benefits derived from these studies in his or her own practice.

View details for Web of Science ID 000079862900024

View details for PubMedID 9661767
The origin of congenital cholesteatoma AMERICAN JOURNAL OF OTOLOGY Karmody, C. S., Byahatti, S. V., Blevins, N., Valtonen, H., Northrop, C. 1998; 19 (3): 292-297
Abstract

This study aimed to document histologically the origin of congenital cholesteatoma in neonatal temporal bones.The study design was a systematic analysis of pediatric temporal bones.The study was performed at the temporal bone laboratory, Tufts University School of Medicine and New England Medical Center, Boston, Massachusetts.We describe histologic findings of a congenital cholesteatoma and a squamous epithelial rest in two postpartum patients. In both patients, the masses were asymptomatic and occurred in the anterosuperior quadrant of the middle ear cleft. This is the first histologic documentation of postpartum congenital cholesteatoma.We believe that these cases represent the first clear histologic documentation of the origin of congenital cholesteatoma.

View details for Web of Science ID 000077356200007

View details for PubMedID 9596177
Are acoustic neuromas encapsulated tumors? 99th Annual Meeting of the American-Academy-of-Otolaryngology-Head-and-Neck-Surgery Kuo, T. C., Jackler, R. K., Wong, K. D., Blevins, N. H., Pitts, L. H. SAGE PUBLICATIONS LTD. 1997: 606–9
Abstract

In articles and chapters on the subject of acoustic neuroma, it is almost invariably stated that they are well-encapsulated tumors. During surgical procedures, blunt mechanical dissection defines a natural subsurface cleavage plane that leaves intact a several millimeter thick rind of tumor surface. Occasionally, as a concession to neural integrity, less than complete resection is elected, leaving behind this "capsular" remnant. To clarify the nature of the surface of acoustic neuromas and to test whether this long held description is indeed correct, a microscopic analysis of 10 surgical specimens was performed. A wedge was harvested from the free surface of the tumor in the mid cerebellopontine angle that included a large, undisturbed section of the tumor surface. Histologic analysis showed that for most of the tumor surface only an extremely thin (3 to 5 microm) layer of connective tissue envelops the tumor. Neoplastic Schwann cells, which extend essentially to the margin of the tumor, were found to be somewhat flattened and compressed in the vicinity of the surface. Although acoustic neuromas are surrounded by a continuous layer of connective tissue, it is so exceptionally thin (on average less than the diameter of a red blood cell) that its edge cannot be visualized intraoperatively by a surgeon. Because the pathologic definition of a capsule is a thick, enveloping layer of connective tissue that is both micro- and macroscopically evident, it must be concluded that acoustic neuromas are nonencapsulated, at least in the conventional sense of the term. The surface peel observed intraoperatively is surgically produced during tumor debulking by cleaving of the looser central component from the more compressed portion of neoplastic cells that lies immediately beneath the free margin of the lesion.

View details for Web of Science ID 000071083200007

View details for PubMedID 9419086
Chiari-I malformation presenting as vocal cord paralysis in the adult Annual Meeting of the American-Academy-of-Otolaryngology-Head-and-Neck-Surgery Blevins, N. H., Deschler, D. G., Kingdom, T. T., Lee, K. C. SAGE PUBLICATIONS LTD. 1997: S191–S194
View details for Web of Science ID 000071083200066

View details for PubMedID 9419145
The promise of multimedia in otology AMERICAN JOURNAL OF OTOLOGY Blevins, N. H. 1997; 18 (3): 283-284
View details for Web of Science ID A1997WX85800001

View details for PubMedID 9149817
Postlaryngectomy dysphagia caused by an anterior neopharyngeal diverticulum OTOLARYNGOLOGY-HEAD AND NECK SURGERY Deschler, D. G., Blevins, N. H., Ellison, D. E. 1996; 115 (1): 167-169
View details for Web of Science ID A1996VA14100030

View details for PubMedID 8758652
COMBINED TRANSPETROSAL-SUBTEMPORAL CRANIOTOMY FOR CLIVAL TUMORS WITH EXTENSION INTO THE POSTERIOR-FOSSA LARYNGOSCOPE Blevins, N. H., Jackler, R. K., Kaplan, M. J., Gutin, P. H. 1995; 105 (9): 975-982
Abstract

Tumors of the clivus, such as chordoma and chondrosarcoma, are generally amenable to an anterior surgical approach. However, approaches that traverse the pharynx or paranasal sinuses do not adequately expose tumor posterolateral to the horizontal course of the intrapetrous carotid artery. In addition, when tumor extends into the posterior fossa, supplemental exposure of neurovascular structures is necessary. A combination petrosectomy and subtemporal craniotomy can provide simultaneous access to the entire clivus as well as the lateral aspect of the midbrain, pons, and upper medulla. The extent of petrosectomy performed depends on a number of factors including status of hearing, facial nerve function, and degree of brainstem compression. In our experience with three patients (two chordomas and one chondrosarcoma), using either the retrolabyrinthine-subtemporal or transcochlear-subtemporal approach, excellent resection was achieved with acceptable morbidity considering the extensive nature of the disease.

View details for Web of Science ID A1995TK18800018

View details for PubMedID 7666734
EXPOSURE OF THE LATERAL EXTREMITY OF THE INTERNAL AUDITORY-CANAL THROUGH THE RETROSIGMOID APPROACH - A RADIOANATOMIC STUDY 97th Annual Meeting of the American-Academy-of-Otolaryngology-Head-and-Neck-Surgery Blevins, N. H., Jackler, R. K. MOSBY-YEAR BOOK INC. 1994: 81–90
Abstract

The recent trend toward earlier diagnosis of acoustic neuroma has substantially increased the number of candidates suitable for surgery with an attempt at hearing preservation. Although the retrosigmoid approach affords the possibility of saving hearing in selected cases, it is associated with a somewhat greater morbidity that other approaches, in terms of persistent headache, cerebrospinal fluid leakage, and cerebellar dysfunction. For this reason, it is best used selectively, when the probability of success in hearing conservation is high. Only a portion of the internal auditory canal can be exposed through the retrosigmoid approach without violating the inner ear, a maneuver that greatly reduces the chance of preserving residual hearing. Substantial variability exists between individuals as to just how far laterally the internal auditory canal may be opened without compromising labyrinthine integrity. To assess the magnitude of this variability, measurements were obtained from 60 high-resolution temporal bone computed tomography scans with a schema intended to model the surgical angle of view used during the retrosigmoid procedure. Intraoperative measurements in a series of cases established that the actual surgical point of view is situated along a line that passes approximately 1.5 cm behind the sigmoid sinus. In this typical surgical position, these data predict that an average of 3.0 mm (32% of the internal auditory canal length) must be left unexposed to avoid labyrinthine injury, with a range between 1.1 mm and 5.3 mm (9% to 58% of the internal auditory canal). Each additional 1-cm retraction on the cerebellum beyond that customarily used affords approximately 1 mm (10% of the internal auditory canal) further exposure of the canal. When considering the retrosigmoid approach to an acoustic neuroma, the clinician is urged to evaluate each patient individually to estimate the amount of internal auditory canal accessible without the removal of a portion of the inner ear. This can be ascertained from an axially oriented, gadolinium-enhanced magnetic resonance imaging scan in the internal auditory canal plane by drawing a line that originates 1.5 cm behind the posterior margin of the sigmoid sinus and passes tangential to the most medial extent of the labyrinth. If this line intersects the posterior margin of the internal auditory canal at least 2 mm lateral to the deepest point of tumor penetration, then adequate exposure with preservation of the labyrinth is likely an achievable goal.

View details for Web of Science ID A1994NX93600016

View details for PubMedID 8028948
FACIAL PARALYSIS DUE TO BENIGN PAROTID TUMORS ARCHIVES OF OTOLARYNGOLOGY-HEAD & NECK SURGERY Blevins, N. H., Jackler, R. K., Kaplan, M. J., Boles, R. 1992; 118 (4): 427-430
Abstract

On rare occasions, facial paralysis associated with a parotid tumor need not denote malignancy. We present two cases in which, contrary to appropriate conventional wisdom, facial paralysis resulted from benign mixed tumors. Each patient presented over 8 years following primary surgical excision. In neither patient was a mass palpable, and facial paralysis was the sole sign of recurrent disease. Each patient had been followed up for several months with a presumptive diagnosis of Bell's palsy prior to discovery of recurrent tumor by radiologic imaging. In each case, at operation the tumor was found to infiltrate the temporal bone via the stylomastoid foramen. Facial paralysis presumably resulted from extrinsic compression of the facial nerve. These two cases add to the few previous reports of facial paralysis due to benign parotid gland tumors.

View details for Web of Science ID A1992HN29900015

View details for PubMedID 1313249
NOVEL INSTRUMENTATION FOR MULTIFIELD TIME-LAPSE CINEMICROGRAPHY COMPUTERS AND BIOMEDICAL RESEARCH KALLMAN, R. F., Blevins, N., COYNE, M. A., Prionas, S. D. 1990; 23 (2): 115-129
Abstract

The most significant feature of the system that is described is its ability to image essentially simultaneously the growth of up to 99 single cells into macroscopic colonies, each in its own microscope field. Operationally, fields are first defined and programmed by a trained observer. All subsequent steps are automatic and under computer control. Salient features of the hardware are stepper motor-controlled movement of the stage and fine adjustment of an inverted microscope, a high-quality 16-mm cine camera with light meter and controls, and a miniature incubator in which cells may be grown under defined conditions directly on the microscope stage. This system, termed MUTLAS, necessitates reordering of the primary images by rephotographing them on fresh film. Software developed for the analysis of cell and colony growth requires frame-by-frame examination of the secondary film and the use of a mouse-driven cursor to trace microscopically visible (4X objective magnification) events.

View details for Web of Science ID A1990CX76800002

View details for PubMedID 2185920

Larry and Sharon Malcolmson Professor in the School of Medicine and Professor, by courtesy, of Neurosurgery at the Stanford University Medical Center

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