Carlson, Matthew L.

Objective: To describe audiometric outcomes following stereotactic radiosurgery (SRS) for jugular paraganglioma (JP). Study Design: Retrospective review. Setting: Tertiary referral center. Patients: Patients with pretreatment serviceable hearing (American Academy of Otolaryngology—Head and Neck Surgery [AAO-HNS] Class A or B) and serial post-SRS audiometric follow-up who underwent Gamma Knife SRS for JP between 1990 and 2017. Intervention(s): Gamma Knife SRS. Main Outcome Measures: Progression to nonserviceable hearing; correlation between baseline hearing and treatment parameters with audiometric outcomes. Results: Of 85 patients with JP who underwent SRS during the study period, 35 (66% female, median age 53) had pretreatment serviceable hearing and serial post-treatment audiometry available for review. Median tumor volume at the time of treatment was 7,080 mm3, median cochlear point dose was 5.8 Gy (interquartile range [IQR] 4.1 to 7.3 Gy), and median marginal and maximum tumor doses were 16 and 32 Gy, respectively. After a median follow-up of 37 months (IQR 16 to 77 mo), the median change in pure-tone average and speech discrimination score in the treated ear was −1.2 dB HL/yr (IQR −4.5 to 0.3) and 0%/yr (IQR 0–3.5%), compared with 0.07 dB HL/yr (IQR −0.03 to 0.12) and 0 %/yr (IQR 0 to 0%) in the contralateral untreated ear. Seven patients developed nonserviceable hearing (AAO-HNS Class C or D) at a median of 13.2 months following SRS (IQR 4.8 to 24 mo). Among those who maintained serviceable hearing, median audiometric follow-up was 42 months (IQR 18 to 77 mo). The Kaplan–Meier estimated rates of serviceable hearing at 1, 3, and 5 years following SRS were 91%, 80%, and 80%, respectively. Sixty percent of patients with pulsatile tinnitus who underwent SRS experienced varying levels of symptomatic improvement following treatment. Conclusion: The short- and intermediate-term risk of progression to nonserviceable hearing following SRS for JP is low. Data regarding the impact of cochlear dose from the vestibular schwannoma literature should not be freely applied to JP, since the impact of SRS parameters on hearing preservation seems to be less significant.

Objective: To examine practice variance of cochlear implant candidacy assessment and off-label indications across centers in the United States. Methods: Cross-sectional survey of the American Neurotology Society (ANS). Results: A total of 81 surveys were returned from ANS members who report regular involvement in cochlear implant care. Overall there was a broad distribution in age and clinical experience, with most respondents reporting ACGME accreditation in neurotology and employment at an academic center. The annual volume of cochlear implant surgeries varied considerably across centers. Seventy-eight percent of respondents performed cochlear implantation for at least one of the following indications within the last 2 years: profound hearing loss in children less than 12 months of age (35, 43%), children with asymmetrical hearing loss where at least one ear was better than performance cutoff for age (25, 31%), adults with asymmetrical hearing where at least one ear was better than the performance cutoff for adult criteria (49, 61%), single-sided deafness (37, 46%), and ipsilateral vestibular schwannoma (28, 35%). Centers with a higher annual implant volume more frequently performed off-label implantation in all queried populations (all, p≤0.001), and performed surgery on infants with congenital deafness at a younger age (p = 0.013), compared with centers with lower surgical volume. When surveyed regarding speech perception testing practices for adult candidacy assessment, 75 (100%) respondents who answered this question reported routine use of AzBio sentences, 42 (56%) CNC word scores, and 26 (35%) HINT testing; only 7 (9%) reported using BKB-SIN testing and 6 (8%) reported using CUNY scores. Fifty-one (68%) reported routine use of speech-in-noise testing to determine adult cochlear implant candidacy, 21 (28%) reported selective use only when patient scores were borderline in quiet, and 3 (4%) reported that their center does not currently use testing in noise for candidacy determination. Nineteen (26%) solely used +10 dB signal-to-noise ratio (SNR), 12 (16%) solely used +5 dB SNR, and 41 (55%) used both +10 and +5 dB SNR. Overall, 19% (N = 14) only perform unilateral implantation in the Medicare population, while 81% (N = 58) consider bilateral implantation. Conclusion: Significant variation in cochlear implant candidacy assessment and off-label implantation exists across centers and providers in the United States resulting in healthcare inequities. The high percentage of surgeons performing implantations for off-label or nontraditional indications reflects the overly restrictive and dated status of current implant guidelines. With greater adoption of more difficult speech perception testing in noise, careful clinical judgment is needed to maintain a favorable risk–benefit balance for prospective implant candidates.

Objective: To examine surgical and device-related cochlear implant practice patterns across centers in the United States. Methods: Cross-sectional survey of the American Neurotology Society (ANS). Results: A total of 81 surveys were returned from ANS members who report regular involvement in cochlear implant care. Overall there was a broad distribution in age and clinical experience, with most respondents reporting Accreditation Council for Graduate Medical Education (ACGME) accreditation in neurotology and employment at an academic center. The annual volume of cochlear implant surgeries varied considerably across centers. Eighty percent of respondents report to offer all three Food and Drug Administration (FDA) approved device brands at their center. In cases where hearing preservation is not a goal, 56% of respondents prefer a perimodiolar electrode design, while 44% prefer a lateral wall electrode. With regard to insertion technique for scala tympani access, 64% prefer inserting through the round window (RW) membrane, 26% prefer an extended round window (ERW) approach, while only 10% prefer a cochleostomy. In cases where hearing preservation is a goal of surgery, 86% of respondents prefer a lateral wall electrode design, while only 14% prefer a perimodiolar electrode design. With regard to insertion technique, 86% prefer RW insertion, while only 9% prefer an ERW approach, and only 5% prefer a cochleostomy. Respondents who prefer RW electrode insertion more commonly use a lateral wall electrode, whereas those who prefer an ERW or cochleostomy approach more commonly use a periomodiolar electrode (p < 0.001). There was a statistically significant greater number of surgeons that prefer lateral wall electrodes (p < 0.001) and RW insertion (p < 0.001) for hearing preservation cases compared with non-hearing preservation cases. For implantation of a hypothetical patient with significant residual hearing, within the range of hybrid device candidacy, the great majority of surgeons prefer a conventional length electrode and only 29% prefer to implant a hybrid device. In cases where hearing preservation is a goal, the overwhelming majority of respondents (96%, n = 74) reported using at least one form of steroid application. Ninety-two percent (n = 71) used intraoperative intravenous steroids, 55% (n = 42) prescribed postoperative oral steroids, 44% (n = 34) bathed the middle ear with steroids during surgery, and 30% (n = 23) prescribed preoperative oral steroids. Together, 65% of respondents use a variation of the tight subperiosteal pocket technique for internal device fixation, 19% prefer a bony well and trough with tie-downs, 10% prefer a bony well and trough without tie-downs, and 5% prefer a screw fixation system. Of the 50 who prefer utilizing a subperiosteal pocket, 31 (62%) incorporate a bony trough and 19 (38%) perform a subperiosteal pocket alone without a bony trough. Conclusion: The results of this survey reflect the evolution in surgical and device-related preferences for cochlear implantation in the United States. An increasing number of surgeons prefer the RW approach for electrode insertion. When hearing preservation is not a goal, there is a near even preference for lateral wall and perimodiolar electrode designs; however, the great majority of surgeons prefer a lateral wall design when attempting to preserve residual acoustic hearing. Even in cases where substantial residual hearing exists, many surgeons prefer conventional length electrodes to hybrid designs. These changes reflect the prioritization of atraumatic surgery and parallel the development of thinner and more atraumatic electrodes.

Background Very few studies have examined vestibular schwannoma (VS) management trends across centers and between providers. The objective of this study is to examine current practice trends, variance in treatment philosophies, and nuanced or controversial aspects of VS care across North America. Methods This is a cross-sectional survey of North American Skull Base Society (NASBS) members who report regular involvement in VS care. Results A total of 57 completed surveys were returned. Most respondents claimed to have over 20 years of experience and the majority reported working in an academic practice with an affiliated otolaryngology and/or neurosurgery residency program. Sixty-three percent of respondents claimed to evaluate VS patients in clinic with both an otolaryngologist and neurosurgeon involved. Eighty-six percent of respondents claimed to operate on VS with both an otolaryngologist and neurosurgeon involved, while only 18% of neurosurgeons and 9% of otolaryngologists performed surgery alone. There was a wide range in the number of cases evaluated at each center annually. Similarly, there was wide variation in the number of patients treated with microsurgery and radiation at each center. Additional details regarding management preferences for microsurgery, stereotactic radiosurgery, stereotactic radiotherapy, and conservative observation are presented. Conclusion VS management practices vary between providers and centers. Overall, most centers employ a multidisciplinary approach to management with collaboration between otolaryngology and neurosurgery. Overall, survey responses concur with previous studies suggesting a shift toward conservatism in management.

Introduction Perioperative care of vestibular schwannoma (VS) patients is extremely variable across surgeons and institutions making practice patterns difficult to standardize. No data currently exist detailing this practice variability. Methods The North American Skull Base Society membership was electronically surveyed regarding perioperative care of surgically operated VS patients. Results There were 87 respondents to the survey. Surgical positioning, surgical approach utilized, and perioperative medical adjuncts are quite variable. However, of those performing retrosigmoid approaches, 49% perform this in the supine position, while 33% use a park-bench position with only 2% using the sitting position. In those performing translabyrinthine approaches, 86% perform this in supine position. Although the use of neuromonitoring appears to be standard of care (98%), other than the seventh nerve, there is substantial variability between respondents regarding monitoring of additional cranial nerves. Postoperative antibiotics are used by 65%, postoperative steroids 81%, and postoperative chemical deep vein thrombosis prophylaxis in 68% of survey respondents. Conclusion Although the perioperative adjuncts to VS surgery are variable, there does appear to be a trend in common practice. Therefore, making surgeons aware of these trends may lead to standardized practice or alternatively trials of these variances to instruct which truly improve patient outcomes.

Abstract MEDICAL THERAPY Target Population Adults with histologically proven or suspected vestibular schwannomas with neurofibromatosis type 2 (NF2). Question What is the role of bevacizumab in the treatment of patients with vestibular schwannomas? Recommendations Level 3: It is recommended that bevacizumab be administered in order to radiographically reduce the size or prolong tumor stability in patients with NF2 without surgical options. Level 3: It is recommended that bevacizumab be administered to improve hearing or prolong time to hearing loss in patients with NF2 without surgical options. Question Is there a role for lapatinib, erlotinib, or everolimus in the treatment of patients with vestibular schwannomas? Recommendations Level 3: Lapatinib may be considered for use in reducing vestibular schwannoma size and improvement in hearing in NF2. Level 3: Erlotinib is not recommended for use in reducing vestibular schwannoma size or improvement in hearing in patients with NF2. Level 3: Everolimus is not recommended for use in reducing vestibular schwannoma size or improvement in hearing in NF2. Question What is the role of aspirin, to augment inflammatory response, in the treatment of patients with vestibular schwannomas? Target Population Any patient with a vestibular schwannoma undergoing observation. Recommendation Level 3: It is recommended that aspirin administration may be considered for use in patients undergoing observation of their vestibular schwannomas. Question Is there a role for treatment of vasospasm, ie, nimodipine or hydroxyethyl starch, perioperatively to improve facial nerve outcomes in patients with vestibular schwannomas? Target Population Adults with histologically proven or suspected vestibular schwannomas. Recommendation Level 3: Perioperative treatment with nimodipine (or with the addition of hydroxyethyl starch) should be considered to improve postoperative facial nerve outcomes and may improve hearing outcomes. PREHABILITATION Question Is there a role for preoperative vestibular rehab or vestibular ablation with gentamicin for patients surgically treated for vestibular schwannomas? Target Population Adults with histologically proven or suspected vestibular schwannomas. Recommendations Level 3: Preoperative vestibular rehabilitation is recommended to aid in postoperative mobility after vestibular schwannoma surgery. Level 3: Preoperative gentamicin ablation of the vestibular apparatus should be considered to improve postoperative mobility after vestibular schwannoma surgery. SURGICAL THERAPY Question Does endoscopic assistance make a difference in resection or outcomes in patients with vestibular schwannomas? Target Population Vestibular schwannoma patients, who are surgical candidates. Inclusion in this analysis required resection utilizing the endoscope, either as the primary operative visualization or microscopic assistance with more than 20 patients treated. Recommendation Level 3: Endoscopic assistance is a surgical technique that the surgeon may choose to use in order to aid in visualization. The full guideline can be found at: https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_9.

Abstract FACIAL NERVE MONITORING Question 1 Does intraoperative facial nerve monitoring during vestibular schwannoma surgery lead to better long-term facial nerve function? Target Population This recommendation applies to adult patients undergoing vestibular schwannoma surgery regardless of tumor characteristics. Recommendation Level 3: It is recommended that intraoperative facial nerve monitoring be routinely utilized during vestibular schwannoma surgery to improve long-term facial nerve function. Question 2 Can intraoperative facial nerve monitoring be used to accurately predict favorable long-term facial nerve function after vestibular schwannoma surgery? Target Population This recommendation applies to adult patients undergoing vestibular schwannoma surgery. Recommendation Level 3: Intraoperative facial nerve can be used to accurately predict favorable long-term facial nerve function after vestibular schwannoma surgery. Specifically, the presence of favorable testing reliably portends a good long-term facial nerve outcome. However, the absence of favorable testing in the setting of an anatomically intact facial nerve does not reliably predict poor long-term function and therefore cannot be used to direct decision-making regarding the need for early reinnervation procedures. Question 3 Does an anatomically intact facial nerve with poor electromyogram (EMG) electrical responses during intraoperative testing reliably predict poor long-term facial nerve function? Target Population This recommendation applies to adult patients undergoing vestibular schwannoma surgery. Recommendation Level 3: Poor intraoperative EMG electrical response of the facial nerve should not be used as a reliable predictor of poor long-term facial nerve function. COCHLEAR NERVE MONITORING Question 4 Should intraoperative eighth cranial nerve monitoring be used during vestibular schwannoma surgery? Target Population This recommendation applies to adult patients undergoing vestibular schwannoma surgery with measurable preoperative hearing levels and tumors smaller than 1.5 cm. Recommendation Level 3: Intraoperative eighth cranial nerve monitoring should be used during vestibular schwannoma surgery when hearing preservation is attempted. Question 5 Is direct monitoring of the eighth cranial nerve superior to the use of far-field auditory brain stem responses? Target Population This recommendation applies to adult patients undergoing vestibular schwannoma surgery with measurable preoperative hearing levels and tumors smaller than 1.5 cm. Recommendation Level 3: There is insufficient evidence to make a definitive recommendation. The full guideline can be found at: https://www.cns.org/guidelines/guidelines-manage-ment-patients-vestibular-schwannoma/chapter_4.

Abstract Please see the full-text version of this guideline (https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_8) for the target population of each recommendation listed below. QUESTION 1 What surgical approaches for vestibular schwannomas (VS) are best for complete resection and facial nerve (FN) preservation when serviceable hearing is present? RECOMMENDATION There is insufficient evidence to support the superiority of either the middle fossa (MF) or the retrosigmoid (RS) approach for complete VS resection and FN preservation when serviceable hearing is present. QUESTION 2 Which surgical approach (RS or translabyrinthine [TL]) for VS is best for complete resection and FN preservation when serviceable hearing is not present? RECOMMENDATION There is insufficient evidence to support the superiority of either the RS or the TL approach for complete VS resection and FN preservation when serviceable hearing is not present. QUESTION 3 Does VS size matter for facial and vestibulocochlear nerve preservation with surgical resection? RECOMMENDATION Level 3: Patients with larger VS tumor size should be counseled about the greater than average risk of loss of serviceable hearing. QUESTION 4 Should small intracanalicular tumors (<1.5 cm) be surgically resected? RECOMMENDATION There are insufficient data to support a firm recommendation that surgery be the primary treatment for this subclass of VSs. QUESTION 5 Is hearing preservation routinely possible with VS surgical resection when serviceable hearing is present? RECOMMENDATION Level 3: Hearing preservation surgery via the MF or the RS approach may be attempted in patients with small tumor size (<1.5 cm) and good preoperative hearing. QUESTION 6 When should surgical resection be the initial treatment in patients with neurofibromatosis type 2 (NF2)? RECOMMENDATION There is insufficient evidence that surgical resection should be the initial treatment in patients with NF2. QUESTION 7 Does a multidisciplinary team, consisting of neurosurgery and neurotology, provides the best outcomes of complete resection and facial/vestibulocochlear nerve preservation for patients undergoing resection of VSs? RECOMMENDATION There is insufficient evidence to support stating that a multidisciplinary team, usually consisting of a neurosurgeon and a neurotologist, provides superior outcomes compared to either subspecialist working alone. QUESTION 8 Does a subtotal surgical resection of a VS followed by stereotactic radiosurgery (SRS) to the residual tumor provide comparable hearing and FN preservation to patients who undergo a complete surgical resection? RECOMMENDATION There is insufficient evidence to support subtotal resection (STR) followed by SRS provides comparable hearing and FN preservation to patients who undergo a complete surgical resection. QUESTION 9 Does surgical resection of VS treat preoperative balance problems more effectively than SRS? RECOMMENDATION There is insufficient evidence to support either surgical resection or SRS for treatment of preoperative balance problems. QUESTION 10 Does surgical resection of VS treat preoperative trigeminal neuralgia more effectively than SRS? RECOMMENDATION Level 3: Surgical resection of VSs may be used to better relieve symptoms of trigeminal neuralgia than SRS. QUESTION 11 Is surgical resection of VSs more difficult (associated with higher facial neuropathies and STR rates) after initial treatment with SRS? RECOMMENDATION Level 3: If microsurgical resection is necessary after SRS, it is recommended that patients be counseled that there is an increased likelihood of a STR and decreased FN function. The full guideline can be found at: https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_8.

Abstract Please see the full-text version of this guideline (https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_3) for the target population of each recommendation listed below. STEREOTACTIC RADIOSURGERY Question 1 What is the overall probability of maintaining serviceable hearing following stereotactic radiosurgery utilizing modern dose planning, at 2, 5, and 10 yr following treatment? Recommendation Level 3 : Individuals who meet these criteria and are considering stereotactic radiosurgery should be counseled that there is moderately high probability (>50%-75%) of hearing preservation at 2 yr, moderately high probability (>50%-75%) of hearing preservation at 5 yr, and moderately low probability (>25%-50%) of hearing preservation at 10 yr. Question 2 Among patients with AAO-HNS (American Academy of Otolaryngology-Head and Neck Surgery hearing classification) class A or GR (Gardner-Robertson hearing classification) grade I hearing at baseline, what is the overall probability of maintaining serviceable hearing following stereotactic radiosurgery, utilizing modern dose planning, at 2, 5, and 10 yr following treatment? Recommendation Level 3 : Individuals who meet these criteria and are considering stereotactic radiosurgery should be counseled that there is a high probability (>75%-100%) of hearing preservation at 2 yr, moderately high probability (>50%-75%) of hearing preservation at 5 yr, and moderately low probability (>25%-50%) of hearing preservation at 10 yr. Question 3 What patient- and tumor-related factors influence progression to nonserviceable hearing following stereotactic radiosurgery using ≤13 Gy to the tumor margin? Recommendation Level 3: Individuals who meet these criteria and are considering stereotactic radiosurgery should be counseled regarding the probability of successful hearing preservation based on the following prognostic data: the most consistent prognostic features associated with maintenance of serviceable hearing are good preoperative word recognition and/or pure tone thresholds with variable cut-points reported, smaller tumor size, marginal tumor dose ≤12 Gy, and cochlear dose ≤4 Gy. Age and sex are not strong predictors of hearing preservation outcome. MICROSURGERY Question 4 What is the overall probability of maintaining serviceable hearing following microsurgical resection of small to medium-sized sporadic vestibular schwannomas early after surgery, at 2, 5, and 10 yr following treatment? Recommendation Level 3 : Individuals who meet these criteria and are considering microsurgical resection should be counseled that there is a moderately low probability (>25%-50%) of hearing preservation immediately following surgery, moderately low probability (>25%-50%) of hearing preservation at 2 yr, moderately low probability (>25%-50%) of hearing preservation at 5 yr, and moderately low probability (>25%-50%) of hearing preservation at 10 yr. Question 5 Among patients with AAO-HNS class A or GR grade I hearing at baseline, what is the overall probability of maintaining serviceable hearing following microsurgical resection of small to medium-sized sporadic vestibular schwannomas early after surgery, at 2, 5, and 10 yr following treatment? Recommendation Level 3: Individuals who meet these criteria and are considering microsurgical resection should be counseled that there is a moderately high probability (>50%-75%) of hearing preservation immediately following surgery, moderately high probability (>50%-75%) of hearing preservation at 2 yr, moderately high probability (>50%-75%) of hearing preservation at 5 yr, and moderately low probability (>25%-50%) of hearing preservation at 10 yr. Question 6 What patient- and tumor-related factors influence progression to nonserviceable hearing following microsurgical resection of small to medium-sized sporadic vestibular schwannomas? Recommendation Level 3: Individuals who meet these criteria and are considering microsurgical resection should be counseled regarding the probability of successful hearing preservation based on the following prognostic data: the most consistent prognostic features associated with maintenance of serviceable hearing are good preoperative word recognition and/or pure tone thresholds with variable cut-points reported, smaller tumor size commonly less than 1 cm, and presence of a distal internal auditory canal cerebrospinal fluid fundal cap. Age and sex are not strong predictors of hearing preservation outcome. CONSERVATIVE OBSERVATION Question 7 What is the overall probability of maintaining serviceable hearing with conservative observation of vestibular schwannomas at 2, 5, and 10 yr following diagnosis? Recommendation Level 3: Individuals who meet these criteria and are considering observation should be counseled that there is a high probability (>75%-100%) of hearing preservation at 2 yr, moderately high probability (>50%-75%) of hearing preservation at 5 yr, and moderately low probability (>25%-50%) of hearing preservation at 10 yr. Question 8 Among patients with AAO-HNS class A or GR grade I hearing at baseline, what is the overall probability of maintaining serviceable hearing with conservative observation at 2 and 5 yr following diagnosis? Recommendation Level 3: Individuals who meet these criteria and are considering stereotactic radiosurgery should be counseled that there is a high probability (>75%-100%) of hearing preservation at 2 yr, and moderately high probability (>50%-75%) of hearing preservation at 5 yr. Insufficient data were available to determine the probability of hearing preservation at 10 yr for this population subset. Question 9 What patient and tumor-related factors influence progression to nonserviceable hearing during conservative observation? Recommendation Level 3: Individuals who meet these criteria and are considering observation should be counseled regarding probability of successful hearing preservation based on the following prognostic data: the most consistent prognostic features associated with maintenance of serviceable hearing are good preoperative word recognition and/or pure tone thresholds with variable cut-points reported, as well as nongrowth of the tumor. Tumor size at the time of diagnosis, age, and sex do not predict future development of nonserviceable hearing during observation. The full guideline can be found at: https://www.cns.org/guidelines/guidelines-manage-ment-patients-vestibular-schwannoma/chapter_3.

Abstract QUESTION 1 What is the expected diagnostic yield for vestibular schwannomas when using a magnetic resonance imaging (MRI) to evaluate patients with previously published definitions of asymmetric sensorineural hearing loss? TARGET POPULATION These recommendations apply to adults with an asymmetric sensorineural hearing loss on audiometric testing. RECOMMENDATION Level 3: On the basis of an audiogram, it is recommended that MRI screening on patients with ≥10 decibels (dB) of interaural difference at 2 or more contiguous frequencies or ≥15 dB at 1 frequency be pursued to minimize the incidence of undiagnosed vestibular schwannomas. However, selectively screening patients with ≥15 dB of interaural difference at 3000 Hz alone may minimize the incidence of MRIs performed that do not diagnose a vestibular schwannoma. QUESTION 2 What is the expected diagnostic yield for vestibular schwannomas when using an MRI to evaluate patients with asymmetric tinnitus, as defined as either purely unilateral tinnitus or bilateral tinnitus with subjective asymmetry? TARGET POPULATION These recommendations apply to adults with subjective complaints of asymmetric tinnitus. RECOMMENDATION Level 3: It is recommended that MRI be used to evaluate patients with asymmetric tinnitus. However, this practice is low yielding in terms of vestibular schwannoma diagnosis (<1%). QUESTION 3 What is the expected diagnostic yield for vestibular schwannomas when using an MRI to evaluate patients with a sudden sensorineural hearing loss? TARGET POPULATION These recommendations apply to adults with a verified sudden sensorineural hearing loss on an audiogram. RECOMMENDATION Level 3: It is recommended that MRI be used to evaluate patients with a sudden sensorineural hearing loss. However, this practice is low yielding in terms of vestibular schwannoma diagnosis (<3%). The full guideline can be found at: https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_2.