Translabyrinthine Vestibular Schwannoma Resection Research Articles

MRI surveillance after translabyrinthine vestibular schwannoma resection and cochlear implantation: is it feasible?

PurposeCochlear implantation in patients with vestibular schwannomas is of increasing importance and interest. Two remaining challenges are the assessment of conduction of the cochlear nerve and the possibility of postoperative surveillance with magnetic resonance imaging. The aim of the current study was to assess follow-up imaging and determine the visibility of the internal auditory canal after vestibular schwannoma resection and cochlear implantation as well as in patients with persistent vestibular schwannomas and cochlear implants in place. Visibility of the internal auditory canal, cerebellopontine angle, and labyrinth were evaluated and graded.MethodsFor this retrospective study, 15 MR examinations of 13 patients after translabyrinthine vestibular schwannoma resection and ipsilateral cochlear implantation were included. All patients had been implanted with an MED-EL cochlear implant. Magnetic resonance imaging was carried out on a 1.5T device. All patients were prepped according to the manufacturer’s recommendations.ResultsAll 15 examinations were carried out without any adverse event during imaging, such as pain, magnet dislocation, or malfunction. The internal auditory canal and the cerebellopontine angle were sufficiently visible in all cases to allow for vestibular schwannoma follow-up.ConclusionMagnetic resonance imaging surveillance of the internal auditory canal following vestibular schwannoma resection and cochlear implantation is feasible and safe with modern implants with a 1.5T magnetic resonance imaging device using metal artifact reduction sequences. Necessary follow-up imaging should not be a contraindication for cochlear implantation in patients with vestibular schwannomas.

Twelve-Month Outcomes of Simultaneous Translabyrinthine Resection and Cochlear Implantation.

Audiometric outcomes at 12 months following simultaneous translabyrinthine (TL) resection of vestibular schwannoma (VS) and cochlear implantation (CI). Prospective cohort study. Tertiary referral center. Adult patients undergoing TL resection of sporadic, unilateral VS ≤ 2 cm were prospectively enrolled. Preoperative testing included binaural AZBio in noise and quiet and unilateral Consonant-Nucleus-Consonant (CNC). Tinnitus Handicap Index (THI) and Speech, Spatial, and Qualities of Hearing (SSQ) questionnaires were also completed. Patients underwent TL resection with simultaneous CI. The preoperative test battery was repeated at 1, 3, 6, and 12 months after activation. Statistical analysis was performed to characterize short-term outcomes (preoperative to 3 months), longer-term outcomes (3-12 months), and overall changes during the preoperative to 12-month period. AZBio, CNC, and THI improved at 3 months with no significant changes thereafter and showed durable improvement at 12 months compared to preoperative testing. While SSQ did not improve at 12 months, a subset of patients showed either recovery or improvement of SSQ-spatial subscores. Patients with cerebellopontine angle tumors had poorer performance, although the impact of tumor size and location could not be deduced based on the small sample size. Patients undergoing simultaneous CI and TL resection of VS had durable improvements in speech perception and tinnitus severity 12 months following surgery. Subjective improvements in localization were not observed. Additional studies are needed to determine which VS patients are optimal candidates for CI.

Intraoperative Cochlear Nerve Monitoring for Vestibular Schwannoma Resection and Simultaneous Cochlear Implantation in Neurofibromatosis Type 2: A Case Series

Neurofibromatosis type 2 (NF2) often results in profound hearing loss and cochlear implantation is an emerging hearing rehabilitation option. However, cochlear implant (CI) outcomes in this population vary, and intraoperative monitoring to predict cochlear nerve viability and subsequent outcomes is not well-established. To review the use of intraoperative electrically evoked cochlear nerve monitoring in patients with NF2 simultaneous translabyrinthine (TL) vestibular schwannoma (VS) resection and cochlear implantation. A retrospective review was performed of 3 patients with NF2 that underwent simultaneous TL VS resection and cochlear implantation with electrical auditory brainstem response (eABR) measured throughout tumor resection. Patient demographics, preoperative assessments, surgical procedures, and outcomes were reviewed. Patients 1 and 3 had a reliable eABR throughout tumor removal. Patient 2 had eABR pretumor removal, but post-tumor removal eABR presence could not be reliably determined because of electrical artifact interference. All patients achieved auditory percepts upon CI activation. Patients 1 and 2 experienced a decline in CI performance after 1 yr and after 3 mo, respectively. Patient 3 continues to perform well at 9 mo. Patients 2 and 3 are daily users of their CI. Cochlear implantation is attainable in cases of NF2-associated VS resection. Intraoperative eABR may facilitate cochlear nerve preservation during tumor removal, though more data and long-term outcomes are needed to refine eABR methodology and predictive value for this population.

Hydroxyapatite cement cranioplasty in the setting of simultaneous translabyrinthine resection of cerebellopontine angle tumors and cochlear implantation.

Cochlear implantation (CI) has become an option for the treatment of hearing loss after translabyrinthine resection of vestibular schwannomas. The surgical video presents the case of a 67-year-old male who had translabyrinthine resection of vestibular schwannoma with simultaneous CI and closure with a hydroxyapatite (HA) cement cranioplasty. HA cement cranioplasty can be utilized in place of abdominal fat graft for the closure of translabyrinthine approaches with similar efficacy and complication profile. To the authors’ knowledge, this is the first reported case of a simultaneous CI and translabyrinthine resection of vestibular schwannoma with HA cement cranioplasty.The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID211

Is Cochlear Implantation Effective for Auditory Rehabilitation Following Vestibular Schwannoma Treatment?

Is Cochlear Implantation Effective for Auditory Rehabilitation Following Vestibular Schwannoma Treatment?

Comparison of Cranioplasty Techniques Following Translabyrinthine Surgery: Implications for Postoperative Pain and Opioid Usage.

To assess differences in postoperative pain, opioid usage, and surgical outcomes between cranioplasty using abdominal fat graft (AFG) versus hydroxyapatite cement (HAC) following translabyrinthine surgery. Retrospective case control. Tertiary referral center. Sixty translabyrinthine procedures were evaluated, including 30 consecutive HAC patients and 30 matched AFG patients. Patients were matched by age, gender, body mass index, and tumor size. Cranioplasty using HAC or AFG following translabyrinthine resection of vestibular schwannoma. Postoperative patient pain ratings, narcotic usage, inpatient length of stay, and complication rates. Patients who underwent HAC cranioplasty had lower postoperative pain scores on several measures (p < 0.05) and less postoperative narcotic usage (mean difference of 36.7 morphine equivalents, p = 0.0025) when compared to those that underwent AFG closure. HAC cranioplasty patients had shorter average length of hospital stay (2.2 vs 3.4 days, p = 0.0441). Postoperative cerebrospinal fluid leaks (one in HAC group, two in AFG group) and skin reactions in AFG closure patients (n = 1) were infrequent. HAC cranioplasty is a safe technique comparable to AFG closure following translabyrinthine surgery which can decrease postoperative pain, narcotic usage, and hospital length of stay.

Clinical Significance of Middle Cerebellar Peduncle Ischemia After Translabyrinthine Vestibular Schwannoma Resection.

To assess clinical symptoms, signs, and radiographic evolution of middle cerebellar peduncle (MCP) diffusion restriction (DR) abnormalities following vestibular schwannoma (VS) resection. Retrospective chart and imaging review. Tertiary-referral neurotology and neurosurgery practice. All consecutive patients who underwent translabyrinthine VS resection over a 2-year period (August 2017-May 2019). Translabyrinthine craniotomy for VS resection. Magnetic resonance imaging (MRI) obtained on postoperative day 1 were reviewed for DR within the pons and cerebellum, with 3 months follow-up MRI to assess for evolution of these vascular changes. Of the 31 patients who met inclusion criteria, MRI demonstrated MCP DR consistent with acute ischemia in 29% (9/31). Of those, two showed corresponding T2 signal abnormalities on follow up MRI consistent with cerebrovascular accident (CVA) within the MCP. Both had severe gait ataxia and dysmetria requiring acute rehabilitation admission and significantly larger tumors (p = 0.02). The remaining seven were asymptomatic, and DR abnormality resolved without lasting radiographic changes. Brainstem compression was present in 100% of patients with postoperative MCP DR (mean MCP ipsilateral:contralateral ratio 0.59 ± 0.19), and 68.1% of those without (mean MCP ratio 0.71 ± 0.25), a difference that was not statistically significant (p = 0.14). In the two patients with CVA, MCP asymmetry persisted, whereas the asymmetry resolved in all others. Asymptomatic acute MCP ischemia discovered incidentally does not require intervention. However, when the ischemic area is large and patients are symptomatic, especially if an acute rehabilitation admission is required, surgeons should suspect true CVA.

Simultaneous Vestibular Schwannoma Resection and Cochlear Implantation Using Electrically Evoked Auditory Brainstem Response Audiometry for Decision-making.

The aim of the study was to evaluate the predictive value regarding postoperative hearing benefit of electrically evoked auditory brainstem response audiometry in sporadic vestibular schwannoma patients undergoing simultaneous tumor resection and cochlear implantation. Patients were included in a prospective study conducted between October 2016 and January 2019. The study was conducted at a tertiary care center. Subjects with unilateral sporadic vestibular schwannoma were screened for study participation. Patients underwent translabyrinthine vestibular schwannoma resection and cochlear implantation simultaneously. Electrically evoked brainstem response audiometry was performed during surgery before and after tumor removal using an intracochlear test electrode to objectively evaluate nerve conduction. Electrically evoked brainstem response audiometry results were correlated with postoperative sound field audiometry, word recognition tests, and speech reception thresholds. Quality of life was assessed before and 12 months after translabyrinthine tumor removal and cochlear implantation. Five patients, three male and two female, were included in the study and followed for at least 1 year after implantation. Three of the five patients are daily cochlear implant users with open set speech recognition. Two individuals with negative intraoperative electrically evoked auditory brainstem response results showed no auditory perception with cochlear implant. Simultaneous translabyrinthine vestibular schwannoma resection and cochlear implantation with intraoperative electrically evoked auditory brainstem response measurements is a feasible and promising option for sporadic vestibular schwannoma patients. Preservation of electrically evoked auditory brainstem responses seems to predict good subsequent hearing outcomes.

Cerebral Venous Sinus Thrombosis After Translabyrinthine Vestibular Schwannoma-A Prospective Study and Suggested Management Paradigm.

To prospectively evaluate the incidence, risk factors and natural history of postoperative cerebral venous sinus thrombosis (pCVST) in translabyrinthine vestibular schwannoma microsurgical resection and propose a potential management paradigm. Prospective, single cohort, multicenter study. State-wide academic tertiary referral centers. Fifty-four consecutive patients who underwent translabyrinthine vestibular schwannoma resection. Incidence of pCVST on postoperative imaging on Day 7, Day 28, and 12 months postoperatively. Patients and tumor characteristics, risk factors, length of stay, intraoperative parameters, complications, and follow-up were analyzed. pCVST was demonstrated in 21 patients (38.9%) on postoperative imaging. All patients with pCVST were treated conservatively and remained asymptomatic in the immediate postoperative period and long-term follow-up. There were no instances of venous infarction, intracranial hemorrhage, or neurological deficits. A majority (61.1%) of pCVST recannalised on long-term follow up with conservative management. There was a statistical association with pCVST and surgery on the side of the non-dominant cerebral venous drainage (n = 17, 80.1%, p = 0.034). Patients with pCVST were significantly more likely to have a postoperative cerebrospinal fluid (CSF) leak (n = 5, 23.8%, p = 0.017). The incidence of pCVST following translabyrinthine vestibular schwannoma resection is much higher than previously recognized. pCVST is more likely to occur when surgery is performed on tumors situated on the side of non-dominant cerebral venous drainage. Despite the high prevalence of this iatrogenic phenomenon, all patients were asymptomatic and a majority resolved, thereby suggesting that conservative management is safe. Correlation between pCVST and increased incidence of CSF leak requires further investigation.

Cochlear patency following translabyrinthine vestibular schwannoma resection: implications for hearing rehabilitation.

To examine when cochlear fibrosis occurs following a translabyrinthine approach for vestibular schwannoma resection, and to determine the safest time window for potential cochlear implantation in cases with a preserved cochlear nerve. This study retrospectively reviewed the post-operative magnetic resonance imaging scans of patients undergoing a translabyrinthine approach for vestibular schwannoma resection, assessing the fluid signal within the cochlea. Cochleae were graded based on the Isaacson et al. system (from grade 0 - no obstruction, to grade 4 - complete obliteration). Thirty-nine patients fulfilled the inclusion criteria. The cochleae showed no evidence of obliteration in: 75 per cent of patients at six months, 38.5 per cent at one year and 27 per cent beyond one year. Most changes happened between 6 and 12 months after vestibular schwannoma resection, with cases of an unobstructed cochlear decreasing dramatically, from 75 per cent to 38.5 per cent, within this time. The progress of cochlear obliteration that occurred between 6 and 12 months following vestibular schwannoma resection indicates that the first 6 months provides a safer time window for cochlear patency.

Translabyrinthine Approach for Resection of Vestibular Schwannoma.

Objectives This video describes the surgical indications, relevant anatomy, and surgical steps of routine translabyrinthine surgery for gross total resection of sporadic vestibular schwannoma. Design The procedure is presented through a surgical instructional video. Setting The surgery took place at tertiary skull base referral center. Parcipant A 47-year-old patient reported with nonserviceable hearing, frequent episodes of vertigo, recurrent severe headache, and a small unilateral right sided vestibular schwannoma. Results Gross total resection with preservation of facial nerve function was achieved. Conclusion This instructional video documents the surgical steps and relevant anatomy for translabyrinthine resection of vestibular schwannoma. The link to the video can be found at: https://youtu.be/CJ2vKMLs7aI .

Quality of Life After Translabyrinthine Vestibular Schwannoma Resection-Reliability of the German PANQOL Questionnaire.

To quantify the postoperative quality of life (QOL) of patients after translabyrinthine surgery for vestibular schwannoma (VS) using the German version of the Penn acoustic neuroma quality-of-life questionnaire (PANQOL) in a university hospital. The PANQOL questionnaire was administered to 72 patients who were treated in our department with translabyrinthine surgery for VS between January 2007 and January 2017. Descriptive evaluations of results were performed in addition to analyses of the reliability and convergent validity of the results and a subgroup analysis. For the first time, QOL was measured in German-speaking VS patients after translabyrinthine surgery. Cronbach's alpha for internal consistency and Guttman's split half, used as measures of reliability, showed values between 0.39 and 0.92 (raw alpha) and 0.58 and 0.98 (Lambda 4), respectively. The mean total PANQOL score of patients after translabyrinthine VS resection was 61.96. The domain "hearing" had the lowest score (50.87), while "facial dysfunction" had the highest score (74.88). Subgroup analysis showed that neither preoperative tumor size nor elapsed time postoperatively significantly influenced QOL outcomes. Depending on the different domains the German PANQOL questionnaire showed poor to good internal consistency, reliability, and convergent validity. Moreover, some VS patients suffer from reduced QOL for a long time after the translabyrinthine procedure, thus psycho-oncological care should be recommended in these cases.

Prospective Evaluation of Patients Undergoing Translabyrinthine Excision of Vestibular Schwannoma with Concurrent Cochlear Implantation.

Translabyrinthine (TL) vestibular schwannoma (VS) resection may be accomplished with preservation of the cochlear nerve, permitting successful, concurrent cochlear implantation. In this single institution, Food and Drug Administration-approved feasibility study, we wished to determine the success and outcomes of concurrent cochlear implantation at the time of TL resection of VS. Prospective cohort. Tertiary referral center. Patients with small VS less than 1.5 cm in size. Concurrent TL VS resection and cochlear implantation. Sound localization and speech understanding. All cochlear nerves were anatomically preserved. Five out of seven patients had auditory precepts at the time of activation. At 1 month following surgery, AzBio scores (0 dB SNR, with sound front, noise to normal ear) were improved by an average of 10% with implant on, persisting to 6 months out from surgery. Localization 1 month after surgery was markedly improved with root mean square 78 degrees ±13 in the "implant off" condition and 41 ± 9 degrees in the "implant on" condition. Average tinnitus severity was reduced in subjects and speech and spatial hearing was improved on speech, spatial and qualities of hearing scale (SSQ). These data demonstrate preservation of electrical hearing in TL VS surgery is consistently possible, and although speech outcomes do not achieve the same levels seen with other etiologies of hearing loss, excellent improvement in sound localization, improved speech understanding, and substantial reductions in tinnitus are achieved.

Middle ear ventilation status postoperatively after translabyrinthine resection of vestibular schwannoma with mastoid obliteration and Eustachian tube occlusion: is the Eustachian tube enough to ventilate the middle ear without the mastoid air cell system?

BackgroundGas pressure balance is essential for maintaining normal middle ear function. The mucosal surfaces of the middle ear, the mastoid air cell system (MACS), and the Eustachian tube (ET) play a critical role in this process; however, the extent that each of these factors contributes to overall middle ear ventilation is unknown. The objective of this study was to determine if the ET alone can maintain normal middle ear pressure without the MACS. To do this, we reviewed subjects who had their MACS completely removed with translabyrinthine (TL) surgery for vestibular schwannoma.MethodsA retrospective chart review was done to collect pre and postoperative tympanometry data from patients who underwent resection of vestibular schwannoma. Data from the operative side was compared to the non-operative side at 2 years post-op.ResultsTwenty-four patients were included in this study. Of these, 63 % achieved a type A tympanogram at 2 years post-op in the TL resection group, implying an ability to maintain middle ear pressure in the absence of a mastoid cavity. Because some had negative pressures post TL resection, the average change in pre and postoperative pressure was -37.5 daPa for the operative side and 7.8 daPa for the non-operative side. This was significantly different.DiscussionThe difference for change in pre and postoperative pressure and compliance between operative and non-operative side might be expected from the ET plugging during TL resection. However, more interesting are those patients in whom the ET presumably reopens, and in these subjects, despite having no mastoid compartment at all, and the space obliterated with fat, they were still able to maintain normal ventilation of the middle ear space.ConclusionOur findings imply that the ET alone is adequate to ventilate at least the reduced middle ear space following TL surgery in most subjects, and perhaps in 100 % if the ET hadn’t been plugged during surgery. Hence, the mastoid air cell system, even when healthy, is not needed to maintain air in the middle year cleft.

Cochlear implantation for hearing rehabilitation in single-sided deafness after translabyrinthine vestibular schwannoma surgery.

The aim of the study was to investigate the option of cochlear implantation (CI) in resultant single-sided deafness associated with unilateral translabyrinthine resection of sporadic vestibular schwannoma (VS). This is a retrospective study performed at Tertiary Care Academic Centre. Following extensive counselling regarding the potential for delayed CI, translabyrinthine VS resection was performed and an intracochlear placeholder was inserted to allow later CI in 11 patients who showed intraoperative microscopic confirmation of preserved cochlear nerve anatomy. Follow-up magnetic resonance imaging (MRI) and promontory testing were performed 1year after surgery to confirm the absence of VS recurrence and viable cochlea. Confirmed CI candidates underwent a second procedure where the placeholder was removed and the CI inserted (4/11). Preimplant unaided and CI-aided evaluations at 12 and 24months were performed for subjective and objective hearing outcomes. Tinnitus suppression was also measured for implant on and off effects. Available audiological data for three patients demonstrated significant hearing benefits for 'speech from deaf/implanted side, noise from the normal-hearing side' in all three patients and localisation ability improved for 2/3 patients. Subjective findings presented similar results. For the two patients with preimplant tinnitus, complete suppression occurred during active CI. CI is beneficial for hearing rehabilitation and tinnitus reduction in SSD patients with remaining viable cochlear nerve after translabyrinthine VS surgery. Counselling on the risks of intracochlear placeholder insertion and the inherent limitations for ongoing MRI investigations of VS recurrence is essential.

Partial Hearing Preservation after Translabyrinthine Vestibular Schwannoma Resection: Case Report and Review of the Literature

Objectives To describe a unique case report of a patient who had partial hearing preservation after translabyrinthine (TL) removal of a vestibular schwannoma (VS). Study Design Case report. Methods The patient's chart was reviewed for hearing levels before and after surgery. Preoperative magnetic resonance imaging (MRI) was compared with postoperative MRI for determination of completeness of tumor removal. The literature on hearing preservation after TL resection is reviewed. Results A 42-year-old woman underwent a TL removal of a VS. The patient's preoperative pure tone average (PTA) was 70 dB and word recognition score (WRS) was 40%. Postoperatively, the patient was able to hear ambient noise in the surgical ear. Her bone conduction PTA was 70 dB, but the WRS score dropped to 2%. One year later, she continues to hear ambient noise and sound in the operative ear. Discussion This is the fifth reported case of partial hearing preservation after TL VS resection. It suggests that by preserving the vestibule and the fluids within the vestibule when possible, there maybe enough residual auditory neural structures for a traditional cochlear implant to benefit such a patient. In addition, preserving the incus when possible may help maintain air conduction to help patients with sound localization.

Contralateral brachial plexus palsy and Horner syndrome following vestibular schwannoma resection: A complication of patient positioning

Skull based neurosurgical cases often require some degree of head rotation during patient positioning to facilitate operative exposure. Extreme head rotation may lead to occlusion of submandibular gland secretions and impaired venous return from the neck, rarely leading to submandibular gland inflammation. An uncomplicated translabyrinthine resection of a vestibular schwannoma was undertaken. Severe submandibular gland inflammation and impaired venous return opposite the site of translabyrinthine vestibular schwannoma resection occurred in the post-operative period. This led to upper brachial plexopathy and Horner syndrome. We present the first known cases of submandibular gland inflammation and hemorrhage resulting in brachial plexopathy and Horner syndrome opposite the site of tumor resection. This case underscores the importance of adequate and safe patient positioning in skull based neurosurgical procedures.

Cochlear obliteration after translabyrinthine vestibular schwannoma surgery

The objective of the study was to determine the temporal occurrence of cochlear obliteration following translabyrinthine vestibular schwannoma resection. A retrospective chart review, cross-sectional study, and sequential analysis of the time series were performed. The retrospective study included patients undergoing translabyrinthine resection for stage T1-T2 vestibular schwannoma from 2007 to 2010 without prior therapy and postoperative follow-up including MRI of the brain and the cerebellopontine angle. Already 3months after surgery a radiographic labyrinthine change was observed in 66.7%, a partial obstruction in 50%, and an obstruction limited to the saccule in 16.7%. Only 33.3% of the patients showed an unchanged inner ear. In consideration of early cochlear obstruction after translabyrinthine vestibular schwannoma resection, temporary follow-up is necessary. Since the indications for cochlear implantation (CI) have been extended, especially concerning patients with single-side deafness, a simultaneous or early second-stage CI after tumour removal should be discussed.

Tinnitus Loudness in Quiet and Noise After Resection of Vestibular Schwannoma

(1) To use a loudness model to assess the influence of loudness recruitment on estimates of the loudness of tinnitus obtained by loudness matching; (2) To compare the effect of background noise on the loudness of tinnitus for individuals who are unilaterally deaf after resection of vestibular schwannoma (VS) and those with idiopathic tinnitus. After translabyrinthine resection of VS, patients experience unilateral deafness and tinnitus in the operated ear. Most complain that their tinnitus is more bothersome in noisy environments, unlike those with idiopathic tinnitus. Unilaterally deaf individuals experiencing tinnitus as a consequence of VS surgery and a comparison group with idiopathic tinnitus. Participants adjusted the level of a probe tone at the frequency where their hearing was best to match the loudness of their tinnitus in quiet; for VS participants, matches were made using a probe in the unaffected ear. Matches were then obtained in the presence of threshold-equalizing noise. For those with idiopathic tinnitus, the probe loudness level, calculated using a loudness model, was almost invariant with hearing loss at the probe frequency and was usually between 20 and 50 phons. For the VS group, the probe loudness level ranged from 6 to 51 phons. With increasing threshold-equalizing-noise level, the loudness match decreased slightly for the comparison group but increased significantly for the VS group. The tinnitus in quiet had a moderate loudness for both groups. Background noise slightly decreased tinnitus loudness for most participants with idiopathic tinnitus but increased tinnitus loudness for VS participants. We propose 2 possible mechanisms for the effect of noise in the VS group.

Gaze-evoked tinnitus following acoustic neuroma resection: a de-afferentation plasticity phenomenon?

A review of the prevalence of gaze-evoked tinnitus in patients who have undergone acoustic neuroma resection was undertaken. The relationship of gaze-evoked tinnitus to tumour size, pre-existing tinnitus, side of the lesion or direction of eye gaze was also analysed. The design was a retrospective review of patients who underwent total unilateral translabyrinthine vestibular schwannoma resection by the senior author. Patients 1 year and 5 years following surgery were assessed. Results were obtained by either direct questioning in a clinical setting or via questionnaire. Data was collected on 36 subjects at an average of 14.6 months postoperatively (range 8-20 months) and on 32 subjects at an average 62 months postoperatively (range 56-68 months). Of the first group, 13 had evidence of gaze-evoked tinnitus (36%) compared with six (19%) of the second. The presence of preoperative tinnitus was a significant variable in univariate and multivariate analyses of the presence of postoperative tinnitus and postoperative gaze-evoked tinnitus. In a reduced model multivariate logistic regression using the two groups combined, the significant independent risk factors for gaze-evoked postoperative tinnitus were female sex (P = 0.046, odds ratio = 4.3), right side surgery (P = 0.02, odds ratio = 5.5) and pre-existing tinnitus (P = 0.008, odds ratio = 24.2). Gaze-evoked tinnitus is more common than previously reported in patients undergoing vestibular schwannoma resection. The underlying pathophysiology remains unclear but neural plasticity following unilateral de-afferentation remains a viable theory. The reduced prevalence over time suggests that this phenomenon may represent an active reinnervation process within the brain, which stabilizes with time. The significance of pre-existing tinnitus suggests that mechanisms of neural reorganization modify an existing physiological pathway. Further research is required into the longevity of this phenomenon, preferably with longitudinal studies.