Screening for vestibular schwannoma: magnetic resonance imaging findings and management

We report the contrast-enhanced magnetic resonance imaging (MRIg) findings from a series of 1139 patients who underwent screening to exclude a diagnosis of vestibular schwannoma. An acoustico-facial nerve bundle tumour was found in 3.1 per cent of patients imaged and vestibular schwannoma incidence is estimated at 1.4 per 100,000 population per annum. MRIg showed an abnormality in 14 per cent of patients; about one third of the findings may have accounted for the presenting symptom(s). A small number of patients had unexpected pathology revealed that required onward referral for further active management.     

Vestibular schwannoma screening: closing the audit loop

Completion of an audit loop assessing vestibular schwannoma screening practice in a sub-regional ENT centre shows good agreement between the guidelines given and indications used for selecting patients to undergo screening MRIg. The proportion of cerebellopontine angle tumours diagnosed is consistent with other reports from the United Kingdom. During the audit period the proportion of patients screened because of unilateral tinnitus increased, but not beyond a reasonable estimate of the proportion that could expect to be screened because of this symptom. There was a reduction in the number of inappropriate scan requests after introduction of a guideline reminder. During the initial period after introducing screening guidelines there is increased screening activity, but this plateaus at a steady level.     

Causes of unilateral sensorineural hearing loss screened by high-resolution fast spin echo magnetic resonance imaging: review of 1,070 consecutive cases

OBJECTIVE: Evaluation of the ability of screening high-resolution, nonenhanced, fast spin echo (FSE) T2-weighted magnetic resonance imaging (MRI) of the internal auditory canal (IAC) and cerebellopontine angle (CPA) to detect nonacoustic schwannoma causes of unilateral sensorineural hearing loss (SNHL). FSE-MRI is equally sensitive in detecting acoustic (vestibular) schwannoma as gadolinium-enhanced MRI, but sensitivity to other causes of hearing loss is unknown. STUDY DESIGN: Retrospective review of screening FSE-MRI studies. SETTING: Academic otology/neurotology and neuroradiology practices. PATIENTS: There were 1,070 patients with unilateral SNHL who underwent radiologic screening for retrocochlear pathology. RESULTS: Normal findings were found in 944 cases. Typical (acoustic) vestibular schwannoma were found in 56 patients. Seventy additional lesions were identified: 27 CPA lesions, 29 inner ear lesions, and 12 intraaxial lesions including 9 infarctions, 1 multiple sclerosis case, 1 mesial temporal lobe sclerosis, and 1 colloid cyst. CONCLUSIONS: High-resolution T2 FSE-MRI of the IAC and CPA is a highly sensitive screening tool for unilateral SNHL, which can detect a variety of lesions in addition to vestibular schwannomas. To our knowledge in 2 years of follow-up in these patients screened for IAC/CPA lesions, no other lesions causing SNHL have been found. High-resolution FSE screening technique, used in conjunction with appropriate clinical prescreening and referral, can provide an equally sensitive method of evaluating unilateral SNHL compared to gadolinium-enhanced T1 MRI while reducing costs and providing distinct advantages in evaluating nonacoustic schwannoma causes of SNHL.     

Change in tinnitus handicap after translabyrinthine vestibular schwannoma excision.

OBJECTIVE: To evaluate the change in tinnitus handicap after translabyrinthine vestibular schwannoma excision. STUDY DESIGN: Prospective administration of the Tinnitus Handicap Inventory (THI) preoperatively and at 3 and 12 months postoperatively. SETTING:: A tertiary referral neuro-otology clinic. PATIENTS: A total of 149 patients from a series of 170 consecutive patients who had vestibular schwannomas excised between May 1998 and July 2002 and who had completed THIs preoperatively and at 3 and 12 months postoperatively. INTERVENTIONS: Translabyrinthine excision of a unilateral sporadic vestibular schwannoma. MAIN OUTCOME MEASURES: THI scores. RESULTS: The number of patients with moderate or severe handicap was 21 (14%) in the preoperative group and 21 (14%) in the 12-month postoperative group. No significant differences in group data were found comparing (by Wilcoxon signed rank test) preoperative data with 3 months postoperative data (p = 0.09), preoperative data with 12 months postoperative data (p = 0.09), and 3 months postoperative data with 12 months postoperative data (p = 0.33). Considering group data, tinnitus handicap is neither alleviated nor exacerbated by translabyrinthine surgery. The application of the validated 20-point criteria for significant change in the status of an individual patient indicates that tinnitus handicap was worse in 10 (6.5%), unchanged in 129 (87%), and better in 10 (6.5%). CONCLUSIONS: The findings of the current study can be used during preoperative patient counseling. In particular, the clinician is now able to take an informed and positive stance about the tinnitus handicap to be expected postoperatively.     

Screening patients with sensorineural hearing loss for vestibular schwannoma using a Bayesian classifier

Objectives: Selecting patients with asymmetrical sensorineural hearing loss for further investigation continues to pose clinical and medicolegal challenges, given the disparity between the number of symptomatic patients, and the low incidence of vestibular schwannoma as the underlying cause. We developed and validated a diagnostic model using a generalisation of neural networks, for detecting vestibular schwannomas from clinical and audiological data, and compared its performance with six previously published clinical and audiological decision‐support screening protocols. Design: Probabilistic complex data classification using a neural network generalization. Settings: Tertiary referral lateral skull base and a computational neuroscience unit. Participants: Clinical and audiometric details of 129 patients with, and as many age and sex‐matched patients without vestibular schwannomas, as determined with magnetic resonance imaging. Main outcome measures: The ability to diagnose a patient as having or not having vestibular schwannoma. Results: A Gaussian Process Ordinal Regression Classifier was trained and cross‐validated to classify cases as ‘with’ or ‘without’ vestibular schwannoma, and its diagnostic performance was assessed using receiver operator characteristic plots. It proved possible to pre‐select sensitivity and specificity, with an area under the curve of 0.8025. At 95% sensitivity, the trained system had a specificity of 56%, 30% better than audiological protocols with closest sensitivities. The sensitivities of previously‐published audiological protocols ranged between 82–97%, and their specificities ranged between 15–61%. Discussion: The Gaussian Process ORdinal Regression Classifier increased the flexibility and specificity of the screening process for vestibular schwannoma when applied to a sample of matched patients with and without this condition. If applied prospectively, it could reduce the number of ‘normal’ magnetic resonance (MR) scans by as much as 30% without reducing detection sensitivity. Performance can be further improed through incorporating additional data domains. Current findings need to be reproduced using a larger dataset.     

The prevalence and onset of gaze modulation of tinnitus and increased sensitivity to noise after translabyrinthine vestibular schwannoma excision.

OBJECTIVE: To determine the prevalence and timing of onset of gaze-modulated tinnitus and increased sensitivity to noise in patients who had undergone translabyrinthine excision of a vestibular schwannoma. STUDY DESIGN: Retrospective questionnaire study. SETTING: University hospital departments of audiology and neurotology. PATIENTS: A cohort of 359 patients who had undergone translabyrinthine excision of a vestibular schwannoma in the period 1997 to 2003. INTERVENTION: Translabyrinthine excision of a unilateral sporadic vestibular schwannoma. MAIN OUTCOME MEASURES: Patient reports and visual analogue scale measures of the timing of onset of gaze-modulated tinnitus and the presence, timing of onset, and persistence of increased sensitivity to noise after surgery. RESULTS: Completed questionnaires were returned by 275 patients (77%), of whom 132 (48%) were men and 143 (52%) were women. Preoperative tinnitus was reported in 150 patients (55%). In 124 of these 150 (83%) the tinnitus persisted, and in 26 of 150 (17%) it abated. Of the 125 patients without preoperative tinnitus, 43 (34%) developed it postoperatively. In 167 (61%) patients of the total group of 275, postoperative tinnitus was reported. Gaze-modulated tinnitus was reported in 53 patients (19%). Somatic-evoked or -modulated tinnitus was reported in 38 patients (14%). In response to the question, "Did you notice being extra sensitive to noise after your operation?," 138 patients (50%) replied that they did. In 111 patients, this persisted. The onset of the modulation of tinnitus was distributed throughout the postoperative period, whereas the onset of increased sensitivity to noise was overwhelmingly in the first 2 months after surgery. CONCLUSION: Gaze modulation of tinnitus after vestibular schwannoma removal was identified in 19% of patients in this series. The onset data did not convincingly argue for any specific mechanism. The prevalence of increased sensitivity to noise is surprising and may represent central hyperacusis in response to unilateral deafferentation of the auditory system.     

Quality of life following microsurgery, radiosurgery and conservative management for unilateral vestibular schwannoma

The best way to manage small and medium-sized vestibular schwannomas is currently a matter of heated debate. As these tumours are not immediately life-threatening, patients are invariably concerned about how management would affect their quality of life. Until now, no study has compared the three treatment modalities in terms of physical, psychological and social wellbeing. This study is based on a retrospective database analysis and postal questionnaire survey of unilateral vestibular schwannoma patients who had either been managed conservatively, or treated with microsurgery or radiosurgery. The results showed that: quality of life (measured by the Glasgow Benefit Inventory) deteriorated after microsurgery, particularly for small tumours; conservative management did not lead to a change in quality of life, and there was a trend towards poorer quality of life following radiosurgery. The findings suggest that a conservative management approach may be more appropriate for small tumours, and that patients who are due to undergo microsurgery or radiosurgery may benefit from counselling about the potential impact of treatment on quality of life.     

A small vestibular schwannoma arising from the inferior vestibular nerve

The investigation of a complaint of unilateral right sensorineural hearing loss led to the identification of a right 3 mm vestibular schwannoma arising from the inferior division of the right vestibular nerve. On investigation the patient was found to have normal caloric function, this being mediated by the superior vestibular nerve. Both transient and distortion product otoacoustic emissions were absent in the right ear, and ABR was abnormal on this side. These findings are of interest as they indicate that this small lesion produced a hearing loss that was both cochlear and retrocochlear. The anatomical finding that the medial auditory efferents run within the inferior vestibular nerve is considered. This patient did not experience tinnitus or hyperacusis despite the site of the lesion arising from the inferior vestibular nerve.     

Head‐shaking nystagmus in patients with a vestibular schwannoma

Head‐shaking nystagmus in patients with a vestibular schwannoma The aim of this study was to calculate the sensitivity of the head‐shake test for peripheral and central vestibular dysfunction associated with unilateral sporadic vestibular schwannoma and to discuss the feasibility of using the head‐shake test as a screening test. The study group consisted of 102 patients with unilateral sporadic vestibular schwannomas, who were seen consecutively for preoperative vestibular assessment, including the head‐shake test. The sensitivity of the head‐shake test for vestibular schwannoma was found to be 22%, and the sensitivity and specificity of the head‐shake test for canal paresis (≥25%) were found to be 27% and 88%, respectively. Patients with abnormalities in the central vestibular system and with a greater canal paresis were more likely to have head‐shake nystagmus, although, even for severe canal paresis, the sensitivity of the test remained low at 36%. The direction of nystagmus was found to be contra‐lateral to the side of the tumour in 86% of patients. It was concluded that the head‐shake test is of insufficient sensitivity to be used as a screening test either for vestibular schwannoma or for vestibular‐system abnormalities associated with vestibular schwannoma. The deduction is made that the head‐shake test is of insufficient sensitivity or specificity to be of clinical value as a screening test for vestibular dysfunction in a general population with symptoms of imbalance.     

听神经瘤术后耳鸣的影响因素分析

目的分析听神经瘤术后耳鸣可能影响因素。方法回顾性分析2018年4月至2019年8月于我院经乙状窦后入路切除听神经瘤的90例患者的临床资料。6个月后对患者进行随访,根据实际情况,完成耳鸣可视化模拟评分量表、术后耳鸣致残量表。统计学分析肿瘤特征、术中情况与耳鸣变化之间的关系。结果90例患者中,12例手术前后均未出现耳鸣。剩余78例中,13例(16.7%)耳鸣消失,18例(23.1%)好转,24例(30.8%)无变化,23例(29.5%)加重。患者年龄(c2=4.753,P=0.029)、术前有无可用听力(c2=5.294,P=0.021)、是否解剖保留耳蜗神经(c2=4.618,P=0.032)对耳鸣预后有影响,性别、肿瘤大小、肿瘤囊实性、内听道内受侵及程度、对小脑及脑干挤压、肿瘤切除程度等因素对耳鸣预后无影响(P>0.05)。结论耳鸣作为听神经瘤常见的症状之一,对患者生活质量影响显著,常常被研究者低估。≥50岁、术前无可用听力和耳蜗神经未保留的患者耳鸣预后较好。耳鸣的治疗应是听神经瘤综合治疗方案的重要组成成分之一。     

Head-shaking nystagmus in patients with a vestibular schwannoma

The aim of this study was to calculate the sensitivity of the head-shake test for peripheral and central vestibular dysfunction associated with unilateral sporadic vestibular schwannoma and to discuss the feasibility of using the head-shake test as a screening test. The study group consisted of 102 patients with unilateral sporadic vestibular schwannomas, who were seen consecutively for preoperative vestibular assessment, including the head-shake test. The sensitivity of the head-shake test for vestibular schwannoma was found to be 22%, and the sensitivity and specificity of the head-shake test for canal paresis (>/=25%) were found to be 27% and 88%, respectively. Patients with abnormalities in the central vestibular system and with a greater canal paresis were more likely to have head-shake nystagmus, although, even for severe canal paresis, the sensitivity of the test remained low at 36%. The direction of nystagmus was found to be contra-lateral to the side of the tumour in 86% of patients. It was concluded that the head-shake test is of insufficient sensitivity to be used as a screening test either for vestibular schwannoma or for vestibular-system abnormalities associated with vestibular schwannoma. The deduction is made that the head-shake test is of insufficient sensitivity or specificity to be of clinical value as a screening test for vestibular dysfunction in a general population with symptoms of imbalance.     

Change in hearing handicap after translabyrinthine vestibular schwannoma excision.

OBJECTIVE: To evaluate the change in hearing handicap after translabyrinthine vestibular schwannoma excision. STUDY DESIGN: Prospective administration of the Hearing Handicap Inventory preoperatively and at 3 and 12 months postoperatively. SETTING: A tertiary referral neurootology clinic. PATIENTS: A total of 119 consecutive patients who had vestibular schwannomas excised between May 1998 and July 2002 and who had completed Hearing Handicap Inventories preoperatively and at 3 and 12 months postoperatively. INTERVENTIONS: Translabyrinthine excision of a unilateral sporadic vestibular schwannoma; pre- and postoperative hearing therapy and rehabilitation. MAIN OUTCOME MEASURES: Hearing Handicap Inventory scores. RESULTS: Sixty-one percent of patients showed no change in their hearing handicap between preoperative and 3-month postoperative measures. Fifty-eight percent showed no change between preoperative and 12-month postoperative measures. Twenty-five percent of patients had a worsening in their hearing handicap when comparing preoperative and 12-month postoperative scores, and these patients were those with a better hearing class preoperatively. Seventeen percent of patients showed an improvement in their hearing handicap over this same time period, and the reasons for this remain unclear. Neither age nor tumor size had an effect on change in hearing handicap. CONCLUSIONS: The findings of the current study can be used during preoperative patient counseling. In particular, the clinician is now able to take an informed and positive stance about the hearing handicap to be expected postoperatively.     

Effects of vestibulo-ocular reflex exercises on vestibular compensation after vestibular schwannoma surgery.

OBJECTIVE: To assess vestibular function in a large group of vestibular schwannoma patients so that we could determine whether simple vestibular exercises speed vestibular dysfunction recovery after tumor removal surgery. STUDY DESIGN: A prospective investigation of the vestibular dysfunction experienced by patients in the first 12 weeks after surgery. SETTING: Vestibular investigation unit at a tertiary referral institution. PATIENTS: Sixty-five patients with identified vestibular schwannoma referred for preoperative vestibular investigations. Thirty-two men and 33 women, with a mean age 51 years (range, 24-77 yr). INTERVENTIONS: There were 27 control patients, 30 exercise patients, and 8 patients that had balance physiotherapy. Exercise patients began simple vestibulo-ocular reflex gaze stabilization exercises 3 days after surgery. MAIN OUTCOME MEASURES: Postoperative vestibular function testing was performed at 2 to 3, 6 to 7, and 10 to 12 weeks after surgery. Objective measurements of vestibular compensation status were as follows: spontaneous nystagmus and sinusoidal harmonic acceleration asymmetry and gain values. Dizziness Handicap Inventory questionnaires were used to assess subjective perceptions. RESULTS: The main findings were reduced dispersion in vestibulo-ocular reflex asymmetry at 2 to 3 weeks, reduced mean in asymmetry at 6 to 7 weeks, less dizziness/imbalance according to the Dizziness Handicap Inventory questionnaire, and that preoperative caloric tests did not predict postoperative severity of vestibular systems. CONCLUSION: This large study provided unique evidence that a program of simple vestibular exercises and education can speed the rate of compensation after vestibular schwannoma surgery.     

Auditory adaptation testing as a tool for investigating tinnitus origin: two patients with vestibular schwannoma

Objective: To enhance the understanding of tinnitus origin by disseminating two case studies of vestibular schwannoma (VS) involving behavioural auditory adaptation testing (AAT). Design: Retrospective case study. Study sample: Two adults who presented with unilateral, non-pulsatile subjective tinnitus and bilateral normal-hearing sensitivity. At the initial evaluation, the otolaryngologic and audiologic findings were unremarkable, bilaterally. Upon retest, years later, VS was identified. Results: At retest, the tinnitus disappeared in one patient and was slightly attenuated in the other patient. In the former, the results of AAT were positive for left retrocochlear pathology; in the latter, the results were negative for the left ear although a moderate degree of auditory adaptation was present despite bilateral normal-hearing sensitivity. Imaging revealed a small VS in both patients, confirmed surgically. Conclusion: Behavioural AAT in patients with tinnitus furnishes a useful tool for exploring tinnitus origin. Decrease or disappearance of tinnitus in patients with auditory adaptation suggests that the tinnitus generator is the cochlea or the cochlear nerve adjacent to the cochlea. Patients with unilateral tinnitus and bilateral, symmetric, normal-hearing thresholds, absent other audiovestibular symptoms, should be routinely monitored through otolaryngologic and audiologic re-evaluations. Tinnitus decrease or disappearance may constitute a red flag for retrocochlear pathology.     

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.     

Intra-labyrinthine schwannoma: two-cases report

Intralabyrinthine schwannomas are uncommon tumours that arise from neural elements in distal branches of the 8th cranial nerve thus they are confined to or have arisen from the vestibule, the semi-circular canals, or the cochlea. The most common presenting symptom is progressive sensory neural hearing loss with or without tinnitus and vestibular symptoms. The diagnostic procedure of choice is gadolinium-enhanced magnetic resonance imaging. Most of these patients can be managed with observation. The indications for surgery are limited. We present 2 patients with a diagnosis of intralabyrinthine schwannoma. A discussion of the management of the intralabyrinthine schwannoma follows.     

The inhibitory effect of intravenous lidocaine infusion on tinnitus after translabyrinthine removal of vestibular schwannoma: a double-blind, placebo-controlled, crossover study.

OBJECTIVE: Intravenous infusion of lidocaine has previously been demonstrated to have a transient inhibitory effect on tinnitus in 60% of individuals. The site of action has variously been proposed as the cochlea, the cochlea nerve, and the central auditory pathways. To determine whether a central site of action exists, this study investigated the effect of intravenous infusion of lidocaine in individuals with tinnitus who had previously undergone translabyrinthine excision of a vestibular schwannoma, which involves division of the cochlear nerve. STUDY DESIGN: Double-blind, placebo-controlled, crossover study. SETTING: University hospital. PATIENTS: Patients who had undergone translabyrinthine removal of a unilateral, sporadic, and histologically proven vestibular schwannoma in the last decade and who had reported postoperative tinnitus at follow-up were identified from a departmental database. Sixteen patients participated (12 men and 4 women). The mean age (+/- standard deviation) of the patients was 58 +/- 8.6 years, and the meantime since operation was 24.3 +/- 7.3 months. INTERVENTION: Solutions of 2% lidocaine hydrochloride and sodium chloride 0.9% were prepared in identical randomized vials. The volume required for 1.5 ml/kg body weight lidocaine was calculated, and this volume was given over 5 minutes for either vial. Blood pressure, pulse oximetry, and cardiac monitoring were set up and performed throughout the infusions. All investigators were blinded. OUTCOME MEASURES: Patient-completed visual analogue scale measures of tinnitus intensity, pitch, and distress, performed before infusion, 5 minutes after infusion onset, and 20 minutes after infusion onset. RESULTS: A significant difference (Wilcoxon signed-rank test, p < 0.05) between placebo and lidocaine infusion conditions was demonstrated for change in visual analogue scale estimates (preinfusion versus 5 min postinfusion) of tinnitus loudness (p = 0.036), pitch (p = 0.026), and distress (p = 0.04). No significant difference between placebo and lidocaine infusion conditions was demonstrated for change in visual analogue scale estimates (preinfusion versus 20 min postinfusion) of tinnitus loudness (p = 0.066), pitch (p = 0.173), and distress (p = 0.058). The indication is of a short-lasting inhibitory effect on tinnitus of lidocaine infusion compared with saline placebo in patients who have undergone translabyrinthine excision of a vestibular schwannoma. CONCLUSION: Intravenous infusion of lidocaine has a statistically significant inhibitory effect on tinnitus in patients who have previously undergone translabyrinthine removal of a vestibular schwannoma. The site of action of lidocaine in this instance must be in the central auditory pathway, as the cochlear and vestibular nerves are sectioned during surgery, and this finding has important implications for the task of identifying other agents that will have a similar tinnitus-inhibiting effect.     

Clinical picture of vestibular schwannoma

PURPOSE: To characterize the clinical picture with vestibular schwannoma, we retrieved 122 patients with vestibular schwannoma from the vestibular unit of the Helsinki University Central Hospital. PROCEDURES: The patients filled out a questionnaire concerning their symptoms, earlier diseases, accidents, and the use of tobacco and alcohol. This information was then completed with results of audiometric, neurotologic and imaging studies. The data were prospectively stored to the database of neurotologic expert system called ONE. RESULTS: The average tumor size was 21 mm. Most of the patients had hearing loss (94%) and tinnitus (83%) but only half of them (49%) had vertigo attacks. The most common initial symptom was hearing loss combined with tinnitus (34%, n=44). Vertigo only was the initial symptom for 12 patients. The mean duration of a vertigo attack was from 5 min to 4 h and the intensity of the attack was regularly mild (37%) or moderate (32%). The vertigo of the vestibular schwannoma patients differed from vertigo in other diseases by the absence (63%) or low intensity (18%) of nausea. Spontaneous nystagmus was present in 56 patients (46%), and caloric asymmetry (>25%) was observed in 66% (n=69). Caloric asymmetry increased with tumor size. The prevalence of headache was 18% (n=21). Sudden slips seldom (7%) occurred. CONCLUSION: Hearing loss and tinnitus are the main symptoms of vestibular schwannoma. Only half of patients have vertigo. Screening to detect vestibular schwannoma is more yielding in sudden deafness patients rather than in patients with Meniere's disease.     

Atypical clinical presentations of vestibular schwannomas.

A significant number of patients with vestibular schwannomas present atypically, with none of the classical symptoms of unilateral sensorineural hearing loss, tinnitus, and/or dysequilibrium. The aim of this study is to highlight those patients with unusual clinical symptoms. STUDY DESIGN: The clinical data of all patients who presented to the vestibular schwannoma clinic at Beaumont Hospital over the past 12 years was prospectively recorded in a computerized database. This paper reviews the atypical presenting symptoms. RESULTS: Three hundred ninety-eight patients were included in this study. A total of 3.7% of patients presented with atypical symptoms only. CONCLUSION: A significant subgroup, 3.7% in our study, did not present with the audiovestibular symptoms classically associated with vestibular schwannoma. Clinician awareness of the atypical clinical symptoms may lead to earlier detection of these lesions.     

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.