Outcomes of Soft Versus Bony Canal Wall Reconstruction with Mastoid Obliteration

OBJECTIVE

To compare recidivism rates, audiometric outcomes, and postoperative complication rates between soft-wall canal wall reconstruction (S-CWR) versus bony-wall CWR (B-CWR) with mastoid obliteration (MO) in patients with cholesteatoma.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary neurotologic referral center.

PATIENTS

Ninety patients aged ≥18 years old who underwent CWR with MO, either S-CWR or B-CWR, for cholesteatoma with one surgeon from January 2011 to January 2022. Patients were followed postoperatively for at least 12 months with or without second-look ossiculoplasty.

INTERVENTIONS

Tympanomastoidectomy with CWR (soft vs. bony material) and mastoid obliteration.

MAIN OUTCOME MEASURES

Recidivism rates; conversion rate to CWD; pre- versus postoperative pure tone averages, speech reception thresholds, word recognition scores, and air-bone gaps; postoperative complication rates.

RESULTS

Middle ear and mastoid cholesteatoma recidivism rates were not significantly different between B-CWR (17.3%) and S-CWR (18.4%, p = 0.71). There was no significant difference in pre- versus postoperative change in ABG (B-CWR, -2.1 dB; S-CWR, +1.6 dB; p = 0.91) nor in the proportion of postoperative ABGs <20 dB (B-CWR, 41.3%; S-CWR, 30.7%; p = 0.42) between B-CWR and S-CWR. Further, there were no significant differences in complication rates between B-CWR and S-CWR other than increased minor TM perforations/retractions in B-CWR (63% vs. 40%, p = 0.03).

CONCLUSIONS

Analysis of recidivism rates, audiometric outcomes and postoperative complications between B-CWR with MO versus S-CWR with MO revealed no significant difference. Both approaches are as effective in eradicating cholesteatoma while preserving relatively normal EAC anatomy and hearing. Surgeon preference and technical skill level may guide the surgeon's choice in approach.

Transcanal Transpromontorial Approaches to the Internal Auditory Canal: A Systematic Review

OBJECTIVE

Exclusive endoscopic (EETTA) and expanded (ExpTTA) transcanal transpromontorial approaches have shown promising results for treating internal auditory canal (IAC) lesions. We reviewed the literature to answer the question: "Do EETTA and ExpTTA achieve high rates of complete resection and low rates of complications in treating patients with IAC pathologies?"

DATA SOURCES

PubMed, EMBASE, Scopus, Web of Science, and Cochrane were searched.

REVIEW METHODS

Studies reporting EETTA/ExpTTA for IAC pathologies were included. Indications and techniques were discussed and meta-analyzed rates of outcomes and complications were obtained with random-effect model meta-analyses.

RESULTS

We included 16 studies comprising 173 patients, all with non-serviceable hearing. Baseline FN function was mostly House-Brackmann-I (96.5%; 95% CI: 94.9-98.1%). Most lesions were vestibular/cochlear schwannomas (98.3%; 95% CI: 96.7-99.8%) of Koos-I (45.9%; 95% CI: 41.3-50.3%) or II (47.1%; 95% CI: 43-51.1%). EETTA was performed in 101 patients (58.4%; 95% CI: 52.4-64.3%) and ExpTTA in 72 (41.6%; 95% CI: 35.6-47.6%), achieving gross-total resection in all cases. Transient complications occurred in 30 patients (17.3%; 95% CI: 13.9-20.5%), with meta-analyzed rates of 9% (95% CI: 4-15%), comprising FN palsy with spontaneous resolution (10.4%; 95% CI: 7.7-13.1%). Persistent complications occurred in 34 patients (19.6%; 95% CI: 17.1-22.2%), with meta-analyzed rates of 12% (95% CI: 7-19%), comprising persistent FN palsy in 22 patients (12.7%; 95% CI: 10.2-15.2%). Mean follow-up was 16 months (range, 1-69; 95% CI: 14.7-17.4). Post-surgery FN function was stable in 131 patients (75.8%; 95% CI: 72.1-79.5%), worsened in 38 (21.9%; 95% CI: 18.8-25%), and improved in 4 (2.3%; 95% CI: 0.7-3.9%), with meta-analyzed rates of improved/stable response of 84% (95% CI: 76-90%).

CONCLUSION

Transpromontorial approaches offer newer routes for IAC surgery, but their restricted indications and unfavorable FN outcomes currently limit their use. Laryngoscope, 133:2856-2867, 2023.

[AUDITORY OUTCOMES OF COCHLEAR IMPLANTATION IN MENIERE'S DISEASE]

BACKGROUND

Cochlear implants are valuable in the auditory rehabilitation of patients with severe to profound hearing loss. However, there is limited data on the outcomes of cochlear implantation in patients with Meniere's disease (MD).

OBJECTIVES

In this study, we aim to evaluate the auditory outcomes of cochlear implantation in patients with MD.

METHODS

A retrospective case series of patients with MD and severe to profound sensorineural hearing loss (SNHL), who underwent cochlear implantation at a tertiary academic center between 2006-2017. Patient's clinical characteristics and audiometric data were reviewed.

RESULTS

The study included 20 ears in 19 patients with MD who underwent cochlear implantation with available pre- and postoperative audiometric data. There were 10 males and 9 females with a mean age of 63 years and a mean follow-up duration of 70.8 months. Pre- and post-implant CNC word recognition scores were 18.31% and 66.89%, respectively (p<0.001). Pre- and post-implant AzBio and/or HINT sentence recognition scores were 12.25% and 68.28% in quiet, respectively (p<0.001), and 18.25% and 63.43% in noise, respectively (p<0.001).

CONCLUSIONS

Cochlear implantation resulted in an improvement of word and sentence recognition scores in MD patients. These results support the role of cochlear implants in the auditory rehabilitation of MD.

DISCUSSION

Dr. Samy received research support from Cochlear Corporation.

Quantification of Fat Graft Retention in the Translabyrinthine Approach Using Magnetic Resonance Imaging Volumetric Analysis

OBJECTIVE

To characterize the viability and volume of autologous free fat grafts over time, determine clinical/patient factors that may affect free fat graft survival and assess the clinical impact of free fat graft survival on patient outcomes in the translabyrinthine approach for lateral skull base tumor resection.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary neurotologic referral center.

PATIENTS

Forty-two adult patients who underwent translabyrinthine craniotomy for resection of a lateral skull base tumor with the mastoid defect filled by autologous abdominal fat graft and subsequently underwent more than one postoperative magnetic resonance imaging (MRI) scans of the brain.

INTERVENTIONS

Mastoid obliteration with abdominal fat after craniotomy, postoperative MRI.

MAIN OUTCOME MEASURES

Rate of fat graft volume loss, fraction retention of original fat graft volume, initial fat graft volume, time to steady-state fat graft retention, rate of postoperative cerebrospinal fluid (CSF) leak, and/or pseudomeningocele formation.

RESULTS

Patients were followed postoperatively with MRI for a mean of 31.6 months with a mean of 3.2 postoperative MRIs per patient. Initial graft size was a mean of 18.7 cm3 with a steady-state fat graft retention of 35.5%. Steady-state graft retention (<5% loss per year) was achieved at a mean of 24.96 months postoperatively. No significant association was found in multivariate regression analysis of clinical factors impact on fat graft retention and CSF leak/pseudomeningocele formation.

CONCLUSIONS

In the use of autologous abdominal free fat graft for filling mastoid defects after translabyrinthine craniotomy, there is a logarithmic decline in fat graft volume over time, reaching steady state in 2 years. Rates of CSF leak or pseudomeningocele formation were not significantly affected by initial volume of the fat graft, rate of fat graft resorption, nor the fraction of original fat graft volume at steady state. In addition, no analyzed clinical factors significantly influenced fat graft retention over time.

Surgical Closure of the Eustachian Tube Through Middle Fossa and Transmastoid Approaches: A Pilot Cadaveric Anatomy Study

BACKGROUND

Cerebrospinal fluid rhinorrhea after temporal bone surgery involves drainage from the Eustachian tube (ET) into the nasopharynx, causing significant patient morbidity. Variable anatomy of the ET accounts for failures of currently used ET obliteration techniques.

OBJECTIVE

To describe the surgical anatomy of the ET and examine possible techniques for ET closure through middle fossa (MF) and transmastoid approaches.

METHODS

We described the surgical anatomy of the ET from the MF and transmastoid approaches in 5 adult cadaveric heads, measuring morphometric and surgical anatomy parameters and establishing targets for definite ET obliteration.

RESULTS

The osseous ET measured an average of 19.53 mm (±1.56 mm), with a mean diameter of 2.24 mm (±0.29 mm). The shortest distance between the greater superficial petrosal nerve and the ET junction was 6.61 mm (±0.61 mm). Shortest distances between the ET junction and the foramen spinosum and posterior border of the foramen ovale were 1.09 mm (±0.24 mm) and 2.03 mm (±0.30 mm), respectively. Closure of the cartilaginous ET may be performed by folding it in on itself, securing it by packing, suturing, or surgical clip ligation.

CONCLUSION

Definite obliteration of the cartilaginous ET appears feasible and the most definite approach to eliminate egress of cerebrospinal fluid to the nasopharynx using the MF approach. This technique may be used as an adjunct to skull base procedures where ET closure is planned.

Petrous Carotid Artery Thrombosis in an Immunocompromised Patient Presenting With Mastoiditis, A Case Report

Objectives:

The neurotologic literature commonly describes venous sinus thrombosis as a complication of mastoiditis. However, thrombosis of the internal carotid artery in the setting of mastoiditis is rarely described. We aim to document a case of carotid artery thrombosis in a patient presenting with mastoiditis.

Methods:

We describe this case and review relevant literature.

Results:

A renal transplant patient was transferred to our hospital with a left middle cerebral artery (MCA) infarct due to acute mastoiditis. Examination demonstrated middle ear effusion and radiologic workup confirmed mastoid infection adjacent to the site of arterial thrombosis. During cortical mastoidectomy and facial recess approach to the middle ear, the petrous carotid bone was found to be dehiscent with pneumatization of the petrous apex. Thrombosis was found to resolve following surgery, IV antibiotics and anticoagulation. Clinically, his focal neurological deficits improved. Proximity of the infectious process to an exposed petrous carotid artery supports the hypothesis that this patient’s thrombus was a product of infectious spread and extra-luminal compression.

Conclusion:

To our knowledge, this is the first report of MCA infarction due to petrous ICA arterial thrombus in the setting of mastoid infection. The patient’s immunocompromised state may have predisposed and contributed to the adverse outcome. We advocate for aggressive management of acute mastoiditis in the immunocompromised to prevent or manage complications (such as venous thrombophlebitis as well as ICA thrombus) as these patients don’t show typical signs of infection and inflammation.

Vestibular Nerve Section via Middle Cranial Fossa Approach

Vestibular nerve section (VNS) is a surgical intervention with hearing preservation used for the treatment of Menière's disease after conservative medical therapy has failed (1,2). With the recent rise in less invasive treatments such as intratympanic gentamicin, VNS has been performed less frequently (3). The middle cranial fossa (MCF) approach for VNS is an uncommon approach due to its technical difficulty. However, it can provide the best distinction of internal auditory canal contents compared with retrosigmoid and retrolabyrinthine approaches. Several advancements in the MCF approach have been described, including the use of intraoperative facial nerve monitoring with electromyography, early removal of the temporal lobe retractor, and the use of an ultrasonic bone aspirator for internal auditory canal decompression (4-6). We demonstrate a case study with a step-by-step approach to successfully sectioning the superior and inferior vestibular nerves while utilizing these advancements and avoiding facial and cochlear nerve injury via the MCF (7). SDC video link: http://links.lww.com/MAO/B409.

Hearing Loss and Tinnitus

A focused history, otoscopic and tuning fork examination and formal hearing testing are the diagnostic pillars for the workup of hearing loss and tinnitus. The causes of hearing loss and tinnitus are varied and range from relatively common age-related hearing loss to rare tumors of the brain and skull base. In this chapter, the authors explain the diagnostic workup of hearing loss and tinnitus, review the pathophysiology of the most common causes, and describe the treatments available.

Vertigo: Streamlining the Evaluation through Symptom Localization

Vertigo is defined as the illusion of internal or external motion. The evaluation of a patient with vertigo in the primary care setting should not necessarily focus on providing a specific diagnosis. Rather, the physician should aim to localize the lesion. This practice streamlines the workup of patients. This article provides detailed information regarding appropriate organ system-based clinical history and the clinical workup of vertigo. Additional signs and symptoms that can facilitate appropriate referral and treatment are highlighted. Although disorder-specific treatments exist the mainstay of therapy for vertigo-induced pathology is physical therapy.

Extended Middle Cranial Fossa Approach for Placement of Auditory Brainstem Implants

OBJECTIVE

Traditionally, auditory brainstem implants (ABIs) have been placed via the translabyrinthine or retrosigmoid approaches. In select patients, a modified extended middle cranial fossa (xMCF) approach with tentorial ligation may be advantageous for vestibular schwannoma (VS) resection and auditory rehabilitation. This manuscript describes the application of this modification of the MCF approach for simultaneous VS resection and ABI placement.

PATIENTS

Patients with neurofibromatosis type 2, profound bilateral sensorineural hearing loss, single functioning sigmoid/jugular venous system, and giant (>4 cm) VS.

INTERVENTIONS

Simultaneous VS resection and ABI placement via a modified xMCF approach with tentorial ligation.

MAIN OUTCOME MEASURES

Extent of tumor removal and brainstem decompression, access to lateral recess of the fourth ventricle, functional hearing improvement, surgical complications.

RESULTS

Two patients met indications and underwent surgery. There were no immediate or delayed surgical complications. Both had subtotal tumor removal with significant decompression of the brainstem and ABI placement. One patient achieved voice and environmental sound awareness at 35 to 55 dbHL across frequencies. The second patient presented with failure to thrive and multiple lower cranial neuropathies in addition to the above-listed indications. She was hospitalized multiple times after surgery due to failure to thrive and recurrent aspiration pneumonia. Her device was never activated, and she expired 1 year after surgery.

CONCLUSIONS

The xMCF with tentorial ligation is an additional approach for tumor resection and ABI placement in selected patients with neurofibromatosis type 2. Future studies will further define when this approach is most applicable as well as the challenges and pitfalls.

Multi-Disciplinary Skull Base Conference and its Effects on Patient Management

OBJECTIVE

Examine the effects of a multi-disciplinary skull base conference (MDSBC) on the management of patients seen for skull base pathology in a neurotology clinic.

METHODS

Retrospective case review of patients who were seen in a neurotology clinic at a tertiary academic medical center for pathology of the lateral skull base and were discussed at an MDSBC between July 2019 and February 2020. Patient characteristics, nature of the skull base pathology, and pre- and post-MDSBC plan of care was categorized.

RESULTS

A total of 82 patients with pathology of the lateral skull base were discussed at a MDSBC during an 8-month study period. About 54 (65.9%) had a mass in the internal auditory canal and/or cerebellopontine angle while 28 (34.1%) had other pathology of the lateral skull base. Forty-nine (59.8%) were new patients and 33 (40.2%) were established. The management plan changed in 11 (13.4%, 7.4-22.6 95% CI) patients as a result of the skull base conference discussion. The planned management changed from some form of treatment to observation in 4 patients, and changed from observation to some form of treatment in 4 patients. For 3 patients who underwent surgery, the planned approach was altered.

CONCLUSIONS

For a significant proportion of patients with pathology of the lateral skull base, the management plan changed as a result of discussion at an MDSBC. Although participants of a MDSBC would agree of its importance, it is unclear how an MDSBC affects patient outcomes.

Determining treatment choices after the cochlear implant evaluation process

OBJECTIVES

Determine the proportion of patients starting the cochlear implant evaluation (CIE) process proceeding to cochlear implantation.Determine which patient factors are associated with undergoing cochlear implantation.

METHODS

Retrospective case series of all patients scheduled for a CIE within a tertiary academic neurotology practice between January 1, 2014 and April 30, 2016. Management pathways of patients undergoing CIE were examined.

RESULTS

Two hundred thirty-seven adult patients were scheduled for CIE during the study period. Two hundred twenty-six patients started the evaluation process, and 203 patients completed full evaluation. Of patients that completed CIE, 166/203 (82%) met criteria for implantation and 37/203 (18%) did not meet criteria. Fifty-nine patients out of 166 patients (36%) meeting criteria did not receive implants and 107/166 (64%) underwent implantation, yielding an overall implantation rate of 47% (107/226) among patients scheduled for CIE. Common reasons for deferring CI among candidates included failure to show up for preoperative appointment (24%), choosing hearing aids as an alternative (22%), patient refusal (21%) and insurance issues (17%). Overall, CIE led to a new adjunctive hearing device (CI or hearing aid) in 113 (113/203, 56%) cases.

CONCLUSION

Fifty-six (113/203) percent of patients who underwent CIE at an academic medical center underwent CI surgery or received an adjunctive hearing device, but 36% (59/166) of candidates did not receive a CI. Patients who forewent CI despite meeting candidacy criteria did so due to cost/insurance issues, or due to preference for auditory amplification rather than CI.

LEVEL OF EVIDENCE

4.

Real-World Compliance With Follow-up in 2,554 Cochlear Implant Recipients: An Analysis of the HERMES Database

BACKGROUND

Traditional paradigms of care recommend close audiology follow-up and regular speech perception outcomes assessment indefinitely for cochlear implant (CI) recipients after device activation. However, there is scant published data on actual compliance with this paradigm in clinical practice.

METHODS

A multi-center cochlear implant database was queried to identify follow-up rates after cochlear implantation. Follow-up rates where speech perception outcomes assessment occurred at 1-, 3-, 6-, 12-, 18-, and 24-months post-activation were determined by tabulating observed follow-up divided by expected follow-up (O/E ratio) expressed as a percentage. To determine all-cause audiology follow-up rates (with or without testing speech perception outcomes assessment), the database patients from two participating centers (one private practice and one academic center) were similarly analyzed using electronic health record (EHR) data to calculate O/E rates where audiology follow-up occurred for any reason.

RESULTS

O/E follow-up rates where speech perception outcomes assessment occurred was 42, 40, 31, 29, 5, and 22% for 1-, 3-, 6-, 12-, 18-, and 24-months post-activation, respectively (n = 2,554). All-cause audiology follow-up rates (with or without speech perception outcomes assessment) using EHR-confirmed data from two individual centers were 97, 94, 81, 66, 41, and 35% at 1-, 3-, 6-, 12-, 18-, and 24-months post-activation visits, respectively (n = 118).

CONCLUSIONS

Compliance with audiology follow-up and speech perception outcomes assessment is generally low and decreases significantly as time post-activation increases. Future paradigms of care for CI should be designed recognizing the significant attrition that occurs with CI follow-up.

Recovery Function of the Late Auditory Evoked Potential in Cochlear Implant Users and Normal-Hearing Listeners

Background: It has been theorized that neural recovery is related to temporal coding of speech sounds. The recovery function of cortically generated auditory evoked potentials has not been investigated in cochlear implant (CI) users.

Purpose: This study characterized the recovery function of the late auditory evoked potential (LAEP) using a masker–probe paradigm in postlingually deafened adult CI users and young normal-hearing (NH) listeners.

Research Design: A case-control study of the late auditory evoked potentials using electrophysiological technique was performed. The LAEP was evoked by 1 kHz tone bursts presented in pairs, with the first stimuli as the maskers and the second stimuli as the probes. The masker–probe intervals (MPIs) were varied at 0.7, 1, 2, 4, and 8 sec, with an interpair interval of 12 sec.

Study Sample: Nine CI users and nine NH listeners participated in this study.

Data Collection and Analysis: The normalized amplitude from the probe response relative to the masker response was plotted as a function of the MPI to form a recovery function. The latency shift for the probe response relative to the masker response was calculated.

Results: The recovery function was approximately linear in log scale of the MPI in NH listeners, while it showed somewhat different recovery patterns with a large intersubject variability in CI users. Specifically, although the probe response was approximately 60 percent of the masker response for the MPI of 0.7 sec in both groups, the recovery function of CI users displayed a nonlinear pattern, with a steeper slope than that of NH listeners. The probe response completely recovered at the MPI of 4 sec in NH listeners and at the MPI of 2 sec in CI users. N1 and P2 latencies from probe responses were shorter than those from masker responses in NH listeners, while no latency difference was found between probe responses and masker responses in CI users.

Conclusions: Our interpretation of these findings is that the faster recovery of the LAEP in CI users is related to abnormal adaptation mechanisms and a less prominent role of the components with longer latencies in the LAEP of CI users. Other mechanisms such as the compromised inhibitory regulation in the auditory system and the aging effect in CI users might also play a role. More research needs to be done to determine whether the slope of the LAEP recovery function is correlated with speech-perception performance.

Visual Speech Recognition: Improving Speech Perception in Noise through Artificial Intelligence

OBJECTIVES

To compare speech perception (SP) in noise for normal-hearing (NH) individuals and individuals with hearing loss (IWHL) and to demonstrate improvements in SP with use of a visual speech recognition program (VSRP).

STUDY DESIGN

Single-institution prospective study.

SETTING

Tertiary referral center.

SUBJECTS AND METHODS

Eleven NH and 9 IWHL participants in a sound-isolated booth facing a speaker through a window. In non-VSRP conditions, SP was evaluated on 40 Bamford-Kowal-Bench speech-in-noise test (BKB-SIN) sentences presented by the speaker at 50 A-weighted decibels (dBA) with multiperson babble noise presented from 50 to 75 dBA. SP was defined as the percentage of words correctly identified. In VSRP conditions, an infrared camera was used to track 35 points around the speaker's lips during speech in real time. Lip movement data were translated into speech-text via an in-house developed neural network-based VSRP. SP was evaluated similarly in the non-VSRP condition on 42 BKB-SIN sentences, with the addition of the VSRP output presented on a screen to the listener.

RESULTS

In high-noise conditions (70-75 dBA) without VSRP, NH listeners achieved significantly higher speech perception than IWHL listeners (38.7% vs 25.0%, P = .02). NH listeners were significantly more accurate with VSRP than without VSRP (75.5% vs 38.7%, P < .0001), as were IWHL listeners (70.4% vs 25.0% P < .0001). With VSRP, no significant difference in SP was observed between NH and IWHL listeners (75.5% vs 70.4%, P = .15).

CONCLUSIONS

The VSRP significantly increased speech perception in high-noise conditions for NH and IWHL participants and eliminated the difference in SP accuracy between NH and IWHL listeners.

The Effect of Side of Implantation on the Cortical Processing of Frequency Changes in Adult Cochlear Implant Users

Cochlear implants (CI) are widely used in children and adults to restore hearing function. However, CI outcomes are vary widely. The affected factors have not been well understood. It is well known that the right and left hemispheres play different roles in auditory perception in adult normal hearing listeners. It is unknown how the implantation side may affect the outcomes of CIs. In this study, the effect of the implantation side on how the brain processes frequency changes within a sound was examined in 12 right-handed adult CI users. The outcomes of CIs were assessed with behaviorally measured frequency change detection threshold (FCDT), which has been reported to significantly affect CI speech performance. The brain activation and regions were also examined using acoustic change complex (ACC, a type of cortical potential evoked by acoustic changes within a stimulus), on which the waveform analysis and the standardized low-resolution brain electromagnetic tomography (sLORETA) were performed. CI users showed activation in the temporal lobe and non-temporal areas, such as the frontal lobe. Right-ear CIs could more efficiently activate the contralateral hemisphere compared to left-ear CIs. For right-ear CIs, the increased activation in the contralateral temporal lobe together with the decreased activation in the contralateral frontal lobe was correlated with good performance of frequency change detection (lower FCDTs). Such a trend was not found in left-ear CIs. These results suggest that the implantation side may significantly affect neuroplasticity patterns in adults.

Hemifacial Spasm as a Rare Clinical Presentation of Idiopathic Intracranial Hypertension: Case Report and Literature Review

OBJECTIVES

To report a rare case of idiopathic intracranial hypertension (IIH) presenting with hemifacial spasm (HFS) and review the current literature.

METHODS

Case report and literature review. The patient's medical record was reviewed for demographic and clinical data. For literature review, all case reports or other publications published in English literature were identified using PUBMED.

RESULTS

A 43-year-old obese female presented with a 2-year history of left HFS.Electroencephalography and head computed tomography were unremarkable. Magnetic resonance imaging demonstrated bilateral anterior inferior cerebellar artery vascular loops involving the internal auditory canals as well as IIH-associated findings. A lumbar puncture was performed and revealed an elevated opening pressure of 26 cm H₂0 cerebrospinal fluid. Acetazolamide treatment was then initiated, resulting in complete resolution of the HFS.

CONCLUSION

HFS may be a rare presenting manifestation of IIH, and treatment of IIH may result in improvement of HFS symptoms. This is the first report of IIH presenting with HFS in the absence of headache or visual change. As a result, this is the first report of HFS as a presenting manifestation of IIH in Otolaryngology literature.

Extended Anterior Petrosectomy Through the Transcranial Middle Fossa Approach and Extended Endoscopic Transsphenoidal-Transclival Approach: Qualitative and Quantitative Anatomic Analysis

BACKGROUND

Petroclival tumors and ventrolateral lesions of the pons present unique surgical challenges. This cadaveric study provides qualitative and quantitative anatomic comparison for an anterior petrous apicectomy through the transcranial middle fossa (TMF) and expanded endoscopic transsphenoidal-transclival approaches.

METHODS

In 10 silicone-injected heads, the petrous apex and clivus were drilled extradurally using middle fossa and endonasal approaches. With in situ and frameless stereotactic navigation, we defined consistent points to compare working areas, bone removal volumes, approach angles, and surgical freedom.

RESULTS

Mean exposed TMF area (21.03 ± 3.46 cm²) achieved a 44.71 ± 4.13° working angle to the brainstem between cranial nerves V and VI. Kawase's rhomboid area measured 1.76 ± 0.34 cm², and bone removal averaged 1.20 ± 0.12 cm³ at the petrous apex. Surgical freedom on the lateral brainstem was higher halfway between cranial nerves V and VI at the center of the rhomboid compared with midline at the basilar sulcus (P < 0.01). After clivectomy and petrous apicectomy, mean exposed expanded endoscopic transsphenoidal-transclival area was 5.29 ± 0.66 cm². Approach from either nostril showed no statistically significant differences in surgical freedom at the foramen lacerum and midpoint basilar sulcus. At the petrous apex, bone volume removed and area exposed were significantly larger for the TMF approach (P < 0.001).

CONCLUSIONS

Expanded transclival anterior petrosectomy through the TMF approach provides an adequate corridor to lesions in the upper ventrolateral pons. The expanded endoscopic transsphenoidal-transclival approach better fits midline lesions not extending laterally beyond cranial nerve VI and C3 carotid when evaluating normal anatomic parameters.

Central Effects of Cranial Nerve Stimulation

The current literature on peripheral cranial nerve stimulation for the purpose of achieving therapeutic effects via altering brain activity is reviewed. Vagus nerve stimulation, which is approved for use in refractory epilepsy, is the most extensively studied cranial nerve stimulator that has direct impact on the central nervous system. Despite the recognized central effects of peripheral cranial nerve stimulation, the mechanism of action for all indications remains incompletely understood. Further research on both mechanisms and indications of central effects of cranial nerve stimulation has the potential to alleviate burden of disease in a large array of conditions.

Engineered oncolytic virus for the treatment of cholesteatoma: A pilot in vivo study

Objective

Determine if oncolytic herpes simplex virus (oHSV) can eradicate cholesteatoma (CHST) in a gerbil model.

Methods

An in vivo model of CHST was developed in Mongolian gerbils by combining Pseudomonas aeruginosa inoculation with double ligation of the external auditory canal (EAC). CHST size and bone thickness were measured using morphometric and volumetric quantification techniques via micro‐computed tomography (micro‐CT). The CHST induction and quantification techniques were then used in an additional group of 10 gerbils (n = 20 ears) to determine the within‐group treatment efficacy of oHSV against CHST in vivo. Treated animals received either one, two, or three intrabullar injections of oHSV between 2 and 6 weeks postinduction of CHST.

Results

The P. aeruginosa inoculation plus double EAC ligation technique successfully induced a range of CHST growth in 100% of the ears in the model‐development group. Osteolytic effects of CHST were observed in 6% of ears whereas osteoblastic effects were observed in 31% of ears. CHST volume decreased by 50% or more in 12 of the 20 ears in the oHSV‐treatment groups. An apparent reversal of osteoblastic effects was also observed in three out of four ears 6 weeks following the third oHSV injection.

Conclusions

P. aeruginosa inoculation plus double EAC ligation reliably induces CHST formation in gerbil. CT‐based volumetric measures are significantly more accurate than single‐slice morphometric area measures for quantification of CHST size. Treatment with oHSV appears to be efficacious for reducing CHST volume by as much as 77% with as few as one treatment.

Level of Evidence

NA

Utility of Magnetic Resonance Imaging in Differentiating Cerebrospinal Fluid Leak from Middle Ear Effusion

Objective

To demonstrate the clinical utility, sensitivity, and specificity of standard magnetic resonance imaging (MRI) sequences in differentiating temporal bone cerebrospinal fluid leaks from all other middle ear effusions.

Study Design

Retrospective imaging review.

Setting

Academic medical center.

Subjects

Patients with cerebrospinal fluid leaks or other middle ear effusions who also underwent MRI.

Methods

Patients were assigned to cerebrospinal fluid leak and other effusion cohorts based on clinical course, findings at surgery/myringotomy, and beta-2 transferrin fluid analysis. Reviewers blinded to the clinical outcome examined T1-weighted, T2-weighted, diffusion-weighted, fluid-attenuated inversion recovery (FLAIR), and 3-dimensional (3D) acquired T2-weighted MRI sequences. For each sequence, fluid imaged in the temporal bone was graded as either similar or dissimilar in signal intensity to cerebrospinal fluid in the adjacent subarachnoid space. Signal similarity was interpreted as being diagnostic of a leak. Test characteristics in predicting the presence of a leak were calculated for each series.

Results

Eighty patients met criteria (41 leaks, 39 other effusions). The 3D T2 series was 76% sensitive and 100% specific in diagnosing a leak, and FLAIR was 44% sensitive and 100% specific. The T1-weighted (73% sensitive, 69% specific), T2-weighted (98% sensitive, 5.1% specific), and diffusion-weighted (63% sensitive, 66% specific) series were less useful.

Conclusions

MRI, with attention to 3D T2 and FLAIR series, is a noninvasive and highly specific test for diagnosing cerebrospinal fluid leak in the setting of an indeterminate middle ear effusion.

Canal reconstruction mastoidectomy: Outcomes comparison following primary versus secondary surgery

OBJECTIVES/HYPOTHESIS

Compare surgical and audiometric outcomes following canal wall reconstruction (CWR) tympanomastoidectomy used as a primary versus secondary approach for treating cholesteatoma.

STUDY DESIGN

Retrospective.

METHODS

Patients treated for primary/secondary cholesteatoma from 2006 to 2017 via CWR were included if they had preoperative/postoperative audiograms, detailed operative note(s), and >12 months' follow-up. Patients were stratified by previous surgical history into two groups: primary CWR group (PG) and secondary CWR group (SG). Surgical outcomes measured were prevalence of recidivistic cholesteatoma, canal cholesteatoma, revision rate, and canal wall down (CWD) conversion rates. Secondary outcomes were prevalence of infection, external canal adhesions/stenoses, and retractions. Audiometric outcomes included change in pure-tone average and air-bone gap.

RESULTS

We stratified 45 patients/ears into the PG and 26 into the SG. The groups did not significantly differ in age, sex, or smoking status. Overall, median follow-up was 35 months. SG patients had higher rates of cholesteatoma detected at staged surgery than did PG patients (P = .04). However, these patients exhibited lower rates of open revision surgery (4% vs.13%) and a significant improvement in air-bone gap (P = .004). Three PG patients (7%) required conversion to CWD versus zero SG patients. Secondary outcomes were similar. Patients who underwent delayed staging >12 months from CWR had increased rates of recidivism and canal adhesion/stenosis.

CONCLUSIONS

CWR was effective for treating cholesteatoma as both a primary and secondary surgical approach. SG patients experienced higher rates of recidivism and secondary canal cholesteatoma. PG patients had higher rates of revision surgery. Staging of ears undergoing CWR is important regardless of prior surgical history.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:2580-2587, 2019.

Evidence for Oncolytic Viral Eradication of Cholesteatoma In Vitro

Cholesteatomas (CHSTs) are congenital or acquired lesions of the temporal bone that are associated with significant morbidity. We hypothesized that an oncolytic herpes simplex virus (oHSV) could preferentially eradicate primary human CHST cells in vitro and that this virus will replicate selectively and efficiently in CHST cells when compared with control cells. In this work, primary human CHST cells were cultured from surgically collected tissue. Cholesteatomas and control cells were grown and infected by oncolytic oHSV. More than 80% CHST cells versus <5% control cells were killed by oHSV. The oHSV showed a significant enhanced cytotoxic effect against CHST cells in a time- and dose-dependent manner. Therefore, this novel therapy has promise as a future treatment to minimize the spread and recurrence of CHST.

Cerebrospinal Fluid Leak Rate after Vestibular Schwannoma Surgery via Middle Cranial Fossa Approach

Objective  Evaluate the cerebrospinal fluid (CSF) leak rate after the middle cranial fossa (MCF) approach to vestibular schwannoma (VS) resection. Design  Retrospective case series. Setting  Quaternary referral academic center. Participants  Of 161 patients undergoing the MCF approach for a variety of skull base pathologies, 66 patients underwent this approach for VS resection between 2007 and 2017. Main Outcome Measure  Postoperative CSF leak rate. Results  There were two instances of postoperative CSF leak (3.0%). Age, gender, and BMI were not significantly associated with CSF leak. In the two cases with CSF leakage, tumors were isolated to the internal auditory canal (IAC) and both underwent gross total resection. Both CSF leaks were successfully treated with lumbar drain diversion. For the 64 cases that did not have a CSF leak, 51 were isolated to the IAC, 1 was located only in the cerebellopontine angle (CPA), and 12 were located in both the IAC and CPA. 62 patients underwent gross total resection and 2 underwent near-total resection. Mean maximal tumor diameter in the CSF leak group was 4.5 mm (range: 3-6 mm) versus 10.2 mm (range: 3-19 mm) in patients with no CSF leak ( p  = 0.03). Conclusions  The MCF approach for VS resection is a valuable technique that allows for hearing preservation and total tumor resection and can be performed with a low CSF leakage rate. This rate of CSF leak is less than the reported rates in the literature in regard to both translabyrinthine and retrosigmoid approaches.

Impact of Motor-Evoked Potential Monitoring on Facial Nerve Outcomes after Vestibular Schwannoma Resection

Objectives:

Assess the utility of intraoperative transcranial facial motor-evoked potential (FMEP) monitoring in predicting and improving facial function after vestibular schwannoma (VS) resection.

Study Design:

Retrospective chart review.

Methods:

Data were obtained from 82 consecutive VS resections meeting inclusion criteria. Sixty-two cases were performed without FMEP and 20 with FMEP. Degradation of FMEP response was defined as a final-to-baseline amplitude ratio of 0.5 or less. House-Brackmann (HB) grade was assessed preoperatively, postoperatively, at follow-up assessments, and it was compared between pre- and post-FMEP cohorts. Positive predictive value (PPV) and negative predictive value (NPV), sensitivity, and specificity of FMEP degradation in predicting facial weakness were calculated.

Results:

In the pre-FMEP group, at length of follow-up (LOF) ⩾9 months, 83.9% (52/62) of patients exhibited HB 1-2 outcome. In the post-FMEP cohort, 75.0% (15/20) exhibited HB 1-2 function at LOF ⩾9 months. There was no difference in rates of HB 1-2 outcomes between groups in the immediate postoperative period ( P = .35) or at long-term follow-up ( P = 1.0). With respect to predicting immediate postoperative facial function, FMEP demonstrated high specificity (88.9%) and moderate sensitivity (54.5%). The PPV and NPV for immediate postoperative facial function were 85.7% and 61.5%, respectively. With respect to long-term (⩾9 months LOF) facial function, intraoperative FMEP was moderately sensitive (71.4%) and highly specific (84.6%); PPV was moderate (71.4%), and NPV was high (84.6%).

Conclusions:

Intraoperative FMEP is highly specific and moderately sensitive in predicting postoperative facial function for patients undergoing VS resection, but its use may not be associated with improved facial nerve outcomes.

Level of Evidence:

4

Cortical Processing of Frequency Changes Reflected by the Acoustic Change Complex in Adult Cochlear Implant Users

The purpose of this study was to examine neural substrates of frequency change detection in cochlear implant (CI) recipients using the acoustic change complex (ACC), a type of cortical auditory evoked potential elicited by acoustic changes in an ongoing stimulus. A psychoacoustic test and electroencephalographic recording were administered in 12 postlingually deafened adult CI users. The stimuli were pure tones containing different magnitudes of upward frequency changes. Results showed that the frequency change detection threshold (FCDT) was 3.79% in the CI users, with a large variability. The ACC N1' latency was significantly correlated with the FCDT and the clinically collected speech perception score. The results suggested that the ACC evoked by frequency changes can serve as a useful objective tool in assessing frequency change detection capability and predicting speech perception performance in CI users.

Middle Fossa Approach for Resection of Vestibular Schwannomas: A Decade of Experience

BACKGROUND

The middle cranial fossa (MCF) approach is a challenging surgical technique for the resection of small and intermediate sized, primarily intracanalicular, vestibular schwannomas (VS), with the goal of hearing preservation (HP).

OBJECTIVE

To describe a decade-long, single institutional experience with the MCF approach for resection of VS.

METHODS

This is a retrospective cohort study of 63 patients who underwent the MCF approach for resection of VS from 2006 to 2016. Audiometric data included pure-tone average (PTA), low-tone pure-tone average (LtPTA), word recognition score, and American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) hearing classification at presentation and follow-up. Patients with postoperative serviceable (AAO-HNS class A-B) and/or useful (AAO-HNS class A-C) hearing were compared to those without HP. Facial nerve function was assessed using the House–Brackmann scale.

RESULTS

The mean age and duration of follow-up were 50 ± 13 yr and 21 ± 21 mo, respectively. The mean tumor size was 10 ± 4 mm. The serviceable and usable HP rates were 54% and 50%, respectively. Some residual hearing was preserved in 71% of patients. Large tumor size (P = .05), volume (P = .03), and extrameatal tumor extension (P = .03) were associated with poor audiometric outcomes. The presence of a fundal fluid cap (P = .01) was a favorable finding. At definitive testing, LtPTA was significantly better preserved than traditional PTA (P = .01). Facial nerve outcomes, tumor control rates, and durability of audiometric outcomes were excellent. 47% of patients pursued aural rehabilitation.

CONCLUSION

In our series, the MCF approach for VS provided excellent rates of tumor and facial nerve function, with durable serviceable HP.

Are Patients with Spontaneous CSF Otorrhea and Superior Canal Dehiscence Congenitally Predisposed to Their Disorders?

Objectives (1) Compare lateral skull base (LSB) height/thickness in patients with spontaneous cerebrospinal fluid otorrhea (CSF), superior canal dehiscence (SCD), acoustic neuromas (AN), and otosclerosis (OTO). (2) Perform correlations between age, body mass index (BMI), sex, and LSB height/thickness. Study Design Case series with chart review. Setting Tertiary referral center. Subjects and Methods Patients with CSF, SCD, AN, and OTO diagnosed from 2006 to 2016 were included if they had high-definition temporal bone computed tomography (CT) and absence of trauma, radiation, chronic ear disease, and/or congenital anomaly. CT-based measurements included LSB height/thickness and pneumatization rates overlaying the external auditory canal (EAC), tegmen tympani (TgT), perigeniculate region (PG), and internal auditory canal (IAC). LSB height/thickness, age, sex, and BMI were statistically correlated. In total, 256 patients and 493 ears (109 CSF, 115 SCD, 269 AN/OTO) were measured. Results Patients with CSF had significantly higher BMIs than the other groups ( P < .001). Patients with CSF and SCD had similar radiographic LSB phenotypes at most measured locations. Both groups exhibited a significantly lower LSB height compared to the AN and OTO groups (mean, 3.9-4.2 mm vs 4.9-5.6 mm; P < .001). Patients with CSF and SCD also demonstrated significantly lower pneumatization rates, as low as 17% to 23% overlaying the PG and IAC ( P < .001). There were no statistically significant correlations found between age, sex, BMI, and LSB height/thickness at any measurement location in any group. Conclusions Patients with CSF and SCD exhibit similar radiographic LSB phenotypes. Age, sex, and BMI do not significantly correlate with LSB height/thickness. These data support the theory that CSF and SCD arise via similar congenital pathoetiologic mechanisms.

Radiographic Evidence of Occult Intracranial Hypertension in Patients with Ménière’s Disease

Objectives

(1) Describe the prevalence of radiographic signs of intracranial hypertension (ICH) in Ménière’s disease (MD) and (2) compare the prevalence of radiographic signs of ICH in MD patients managed medically to those managed surgically.

Study Design

Case-control study.

Setting

Academic neurotologic practice.

Subjects and Methods

Adult MD patients (aged ≥17 years) treated from 2011 to 2015 were reviewed. Inclusion required magnetic resonance imaging (MRI) of the head and follow-up >6 months. Patients with intracranial tumors, mass effect, trauma, previous intracranial surgery, and glaucoma were excluded. MD patients were separated by administered treatment into medical and surgical subgroups. Cochlear implant (CI) recipients served as radiographic controls. Eighty-four MD patients (46 surgical, 38 medical) and 37 CI controls were assessed. MRI measurements assessed for empty/partial sella (ES/PS), dilated/tortuous optic nerve sheath (ONS), and posterior globe flattening (PGF).

Results

Mean age was 53.8 ± 1.3 years and median body mass index (BMI) was 28.2 kg/m2. Of the patients, 64% were female and 92% were white. MRI findings in the MD cohort were as follows: ES/PS, 46.4%; ONS change, 42.8%; and PGF, 8.3%. The prevalence of ONS change was higher in MD patients than in controls (42.8% vs 13.5%, P = .003). The surgical MD group had higher prevalence of ONS change (52%) compared with the medical group (31.5%, P = .05) and controls (13.5%, P = .0004). The surgical group had a higher prevalence of ≥2 simultaneous MRI findings compared with medical MD patients (39% vs 10%, P = .01) and controls (14%, P = .01).

Conclusion

MD patients demonstrate a high prevalence of radiographic signs of ICH. MD patients who required surgery had a greater prevalence of radiographic signs of ICH compared with non-MD patients and medically managed MD patients.

Idiopathic intracranial hypertension: Contemporary review and implications for the otolaryngologist

OBJECTIVES

1) Review controversies pertaining to the pathophysiology, diagnosis, and treatment of idiopathic intracranial hypertension. 2) Discuss the evolving role of otolaryngologists in managing this disease and related disorders.

DATA SOURCES

Primary literature review, Centers for Disease Control and Prevention website, International Classification of Headache Disorders, Second Edition.

METHODS

A comprehensive review of the primary literature was performed from 1990 to 2016 utilizing keywords idiopathic intracranial hypertension, pseudotumor cerebri, benign intracranial hypertension, spontaneous cerebrospinal fluid leak, and encephalocele. Articles were included at the discretion of the authors based on novel and/or historical contributions to the literature.

RESULTS

The incidence of idiopathic intracranial hypertension is increasing along with the obesity epidemic. Undiagnosed patients may present to otolaryngologists with pulsatile tinnitus, dizziness, sleep apnea, and spontaneous cerebrospinal fluid leaks. Although diagnosis is predicated upon imaging findings and lumbar puncture, radiographic signs including empty sella, optic nerve dilation, and globe flattening may suggest the diagnosis. The most effective intervention is weight loss combined with acetazolamide. Surgery is reserved for severe or refractory symptoms and can be highly morbid. Otolaryngologists are increasingly responsible for managing a number of secondary disorders including cerebrospinal fluid rhinorrhea and otorrhea. Failure to manage intracranial hypertension may lead to adverse surgical outcomes.

CONCLUSIONS

The knowledge base for idiopathic intracranial hypertension has greatly expanded over the past 25 years. This disease is associated with a number of conditions directly relevant to otolaryngologists. A keen understanding of this disorder and its management may optimize outcomes in a growing number of patients. Laryngoscope, 128:248-256, 2018.

Analysis of Audiometric Outcomes following Combined Middle Cranial Fossa/Transmastoid Approaches for Spontaneous Cerebrospinal Fluid Otorrhea

Outcome Objectives

To (1) explore audiometric outcomes following use of a combined transmastoid/middle cranial fossa (TM-MCF) approach in the treatment of spontaneous cerebrospinal fluid (CSF) otorrhea and (2) determine the influence of dehiscence location and reconstructive methodology on audiometric outcomes.

Study Design

Case series with chart review.

Setting

Tertiary care center.

Subjects and Methods

Adults with spontaneous CSF otorrhea were reviewed from 2007 to 2016 if they underwent combined TM-MCF. Definitive audiometric evaluations were performed at least 3 months postoperatively. The primary outcomes measures were pre- to postoperative changes in pure-tone average (PTA) and air-bone gap (ABG). Two subset analyses were performed for audiometric outcomes comparisons: first, patients with skull base dehiscences anterior to the ossicular chain were compared with those with posterior dehiscences. Second, patients undergoing skull base resurfacing plus abdominal fat graft mastoid obliteration (AFGMO) were compared with those undergoing resurfacing alone.

Results

A total of 28 patients and 31 ears were reviewed. There was 1 recurrent leak (3.5%). The cohort demonstrated significant improvement in mean postoperative ABG ( P = .008) but not PTA. On subset analysis, ears with posterior dehiscences demonstrated significant improvements in PTA ( P = .03) and ABG ( P = .05), while ears with anterior dehiscences did not. In addition, ears undergoing resurfacing plus AFGMO achieved significant improvements on all parameters ( P = .01). Only 3 of 15 ears undergoing resurfacing plus AFGMO experienced worsened postoperative hearing.

Conclusion

Use of the combined TM-MCF approach for treating spontaneous CSF otorrhea achieved good audiometric outcomes. Patients with skull base dehiscences posterior to the ossicles and those undergoing skull base resurfacing plus AFGMO achieved the most favorable results.

Middle Ear Obliteration with Blind-Sac Closure of the External Auditory Canal for Spontaneous CSF Otorrhea

Outcome Objectives To (1) identify unique features of patients who underwent middle ear/mastoid obliteration with blind-sac closure of the external auditory canal for spontaneous cerebrospinal fluid (CSF) otorrhea and (2) explore outcomes. Study Design Case series with chart review. Setting Tertiary care center. Subjects and Methods Adults treated for spontaneous cerebrospinal fluid otorrhea from 2007 through 2015 were reviewed and stratified into 2 groups based on the surgery performed: (1) 11 patients underwent middle ear/mastoid obliteration with blind-sac closure of the external auditory canal and (2) 26 patients underwent other procedures. Demographics, body mass index, revised cardiac risk index, Duke Activity Status Index scores, and anticoagulation use were documented. Audiologic data were gathered from pre- and postoperative visits. The primary outcome measure was leak recurrence. Complications were tabulated. Results Poor preoperative hearing was a relative indication for obliteration. Obliteration patients had higher body mass index (43.2 vs 34.9 kg/m2; P < .05), incidence of super-morbid obesity (45% vs 7.6%; P = .015), anticoagulation usage (36% vs 0%; P = .004), cardiac risk scores (1.2 vs 0.1 dB; P < .0004), and Duke Activity Status Index scores. There was 1 leak recurrence (9%). Major and minor complication rates were 9% and 36%, respectively. Mean follow-up was 30.8 ± 8.6 months. Conclusion Middle ear and mastoid obliteration with blind-sac closure of the external auditory canal is effective for treating spontaneous CSF otorrhea. The small cohort reviewed did not experience any major perioperative morbidity. The technique may be best suited for patients with poor hearing, the infirm, and those in whom craniotomy is contraindicated.

Intraoperative Neurophysiological Monitoring of the Laryngeal Nerves During Anterior Neck Surgery: A Review

Contributions to the literature on intraoperative neuro monitoring (IONM) during endocrine and head and neck surgery have increased over recent years. Organizational support for neural monitoring during surgery is becoming evident and is increasingly recognized as an adjunct to visual nerve identification. A comprehensive understanding of the role of IONM for prevention of nerve injuries is critical to maximize safety during surgery of the anterior compartment of the neck. This review will explore the potential advantages of IONM to improve the outcomes among patients undergoing anterior neck surgery.

Management of Pseudomeningocele Following Neurotologic Procedures

OBJECTIVES: A pseudomeningocele results from the escape of cerebrospinal fluid through a dural defect with trapping of subarachnold fluid in surrounding soft tissue. The present study evaluates the incidence of pseudomeningocele following neurotologic procedures and delineates an algorithm for management.

METHODS: A retrospective review of 375 consecutive patients undergoing neurotologic procedures at a single institution identified 17 patients with the postoperative complication of pseudomeningocele.

RESULTS: The incidence of pseudomeningocele formation was 4.5% in the present study. Fourteen pseudomeningoceles resolved with nonoperative management including pressure dressing, bed rest, and lumbar spinal drainage. Three patients failed nonoperative management and required surgical procedures for resolution. All patients ultimately had resolution of their pseudomeningocele.

CONCLUSION: Skull-base pseudomeningoceles occur as a complication following neurotologic procedures and can cause complications as they enlarge. The majority of these cases can be dealt with in a nonsurgical manner, but those failing to respond to conservative management should be considered for surgical intervention.

Intraoperative seizure and cerebrospinal fluid leak during adult cochlear implant surgery

OBJECTIVE AND IMPORTANCE

To report a rare case of cerebrospinal fluid gusher and subsequent seizure immediately after cochlear implant electrode insertion.

CLINICAL PRESENTATION

After the cochlear implant electrode was inserted, brisk flow of 10 mL of cerebrospinal fluid was seen. The electrode was promptly inserted and the leak was additionally sealed with fascia. Seconds later, the patient had a tonic-clonic seizure lasting 30 seconds. Two additional episodes occurred during the case. Her postoperative course was uneventful with no subsequent seizures. The device has been successfully activated. Intervention & Technique: Postoperative imaging showed correct intracochlear placement of the electrode as well as an incidental enlarged vestibular aqueduct. Neurology consultation including electroencephalogram was unremarkable.

CONCLUSION

To our knowledge, this is the first report of a seizure temporally associated with cochlear implant electrode insertion. The significance and possible casual relationship between these two events is discussed.

Cochlear implantation after radiation therapy for acoustic neuroma

Neurofibromatosis type 2 (NF-2) represents the complex issue of hearing restoration after treatment for a patient with bilateral acoustic neuromas. This scenario is difficult for skull base teams considering that all treatment options (including observation of tumors) pose a risk to the patient for further or total hearing loss. In this case of a patient with bilateral deafness, restoration options were auditory brainstem or cochlear implantation (CI). The deciding factor for CI was based on the presence of a functioning cochlear nerve and blood supply. Ultimately, treatment with radiation therapy and subsequent CI proved effective as evidenced by dramatic improvement in communication (with lip reading cues) and speech perception on 1-year audiologic testing. Radiosurgery followed by CI may represent a potential emerging option for patients with NF-2.

Radiographic Assessment and Surgical Implications of Arcuate Eminence Pneumatization

BACKGROUND

The middle cranial fossa (MCF) approach is a valuable yet technically challenging technique. Identification of the superior semicircular canal (SCC) using the arcuate eminence (AE) was proposed as a surface landmark. However, the AE is sometimes absent, with inconsistent relationship to the SCC. Air cells in the AE area facilitate safer identification of the SCC. The aim of this study is to determine the radiographic prevalence of AE pneumatization.

METHODS

Two hundred consecutive fine-cut temporal bone CT scans were retrospectively reviewed. The region of the petrosal bone at and above the level of the SCC dome was assessed for the presence of air cells, and graded 0 (no pneumatization) to 2 (well pneumatized).

RESULTS

Four hundred temporal bones were studied. The average age was 49 years (range 18-89). Of all AE assessments, 47 (12%) were nonpneumatized, 62 (15%) partially pneumatized, and 291 (73%) well pneumatized. There was no significant correlation between patient age and pneumatization grade (p = 0.72).

CONCLUSION

The SCC is a valuable landmark in MCF surgery as it holds consistent relationships to adjacent critical structures. Surrounding air cells should facilitate safer initial identification of the SCC, as the AE region is well pneumatized in 73% of patients.

Auditory cortical activity to different voice onset times in cochlear implant users

OBJECTIVE

Voice onset time (VOT) is a critical temporal cue for perception of speech in cochlear implant (CI) users. We assessed the cortical auditory evoked potentials (CAEPs) to consonant vowels (CVs) with varying VOTs and related these potentials to various speech perception measures.

METHODS

CAEPs were recorded from 64 scalp electrodes during passive listening in CI and normal-hearing (NH) groups. Speech stimuli were synthesized CVs from a 6-step VOT /ba/-/pa/ continuum ranging from 0 to 50 ms VOT in 10-ms steps. Behavioral measures included the 50% boundary point for categorical perception ("ba" to "pa") from an active condition task.

RESULTS

Behavioral measures: CI users with poor speech perception performance had prolonged 50% VOT boundary points compared to NH subjects. The 50% boundary point was also significantly correlated to the ability to discriminate consonants in quiet and noise masking. Electrophysiology: The most striking difference between the NH and CI subjects was that the P2 response was significantly reduced in amplitude in the CI group compared to NH. N1 amplitude did not differ between NH and CI groups. P2 latency increased with increases in VOT for both NH and CI groups. P2 was delayed more in CI users with poor speech perception compared to NH subjects. N1 amplitude was significantly related to consonant perception in noise while P2 latency was significantly related to vowel perception in noise. When dipole source modelling in auditory cortex was used to characterize N1/P2, more significant relationships were observed with speech perception measures compared to the same N1/P2 activity when measured at the scalp. N1 dipole amplitude measures were significantly correlated with consonants in noise discrimination. Like N1, the P2 dipole amplitude was correlated with consonant discrimination, but additional significant relationships were observed such as sentence and word identification.

CONCLUSIONS

P2 responses to a VOT continuum stimulus were different between NH subjects and CI users. P2 responses show more significant relationships with speech perception than N1 responses.

SIGNIFICANCE

The current findings indicate that N1/P2 measures during a passive listening task relate to speech perception outcomes after cochlear implantation.

Feasibility of the Ultrasonic Bone Aspirator in Retrosigmoid Vestibular Schwannoma Removal

Objective:

Postoperative headache is an undesirable consequence of retrosigmoid vestibular schwannoma (VS) removal. An ultrasonic bone aspirator (UBA) may reduce headache by minimizing subarachnoid bone dust dispersion. The feasibility of removing internal auditory canal (IAC) bone with a UBA is unknown. This study assessed volume and duration of IAC bone removal in clinical and laboratory settings.

Study Design:

(1) Retrospective review of radiologic data and intraoperative videos. (2) Cadaveric temporal bone model.

Setting:

(1) Tertiary care medical center. (2) Laboratory.

Subjects Methods:

We calculated the volume of IAC bone drilled during retrosigmoid VS removal using postoperative computed tomography scans. We then measured the time spent actively drilling IAC bone by analyzing operative videos. Finally, we measured bone ablation rates in a cadaveric temporal bone model using a drill and UBA.

Results:

The mean ± SD volume of IAC bone removed during surgery was 0.32 ± 0.17 mL (n = 9). The time spent actively removing IAC bone with a drill was only 10.4 ± 3.5 minutes, less than a third of the total IAC opening time of 34.2 ± 13.1 minutes (n = 5). On cadaveric specimens, the UBA removed bone at 0.21 ± 0.03 or 0.35 ± 0.07 µL/s at 15% or 50% power, respectively (n = 4). This extrapolates to 15.0 ± 3.0 to 25.0 ± 3.9 minutes to remove the same 0.32 mL from surgery.

Conclusions:

The volume and duration of IAC bone removal during retrosigmoid VS surgery are small. Using a UBA at low power instead of a drill would extend the length of surgery by 5 to 15 minutes, with the theoretical potential for reducing headache.

Reduction of Bone Dust with Ultrasonic Bone Aspiration

Objective

Postoperative headache is not uncommon after retrosigmoid vestibular schwannoma removal. Bone dust dispersed into the subarachnoid space during drilling may be responsible. If dispersion could be reduced, headache incidence might be decreased. An ultrasonic bone aspirator (UBA) containing an integrated suction at the tip may more effectively suction bone dust created during bone removal. The objective is to determine whether a UBA results in less bone dust dispersion than a standard otologic drill.

Study Design

Cadaveric temporal bone quantitative model.

Setting

Laboratory.

Subjects and Methods

Temporal bone blocks were placed in a watertight enclosure. Under irrigation, bone was removed by use of either a drill or a UBA. The settings of the UBA were varied. The irrigant containing bone dust was microfiltered, and bone dust was weighed. Differences were compared across groups (n = 2-9 per group). Ablation times were also recorded (n = 3 per group).

Results

Only 3% (SD = 1.6%, n = 7) of the drilled bone mass was re-collected as bone dust with the UBA under optimized settings (power = 15%, suction = 100%, irrigation = 15 mL/min) compared with 81% (SD = 10%, n = 4) with the drill and external suction ( P < .001). Increasing UBA power and reducing suction led to significantly more bone dust dispersal than with optimized settings. Varying irrigation did not have a significant effect. Bone ablation time was 1.4 times longer with the UBA at 50% power compared with the drill at maximum power.

Conclusions

The UBA resulted in approximately 25 times less bone dust dispersion than the otologic drill at optimized settings.