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.     

Motorized head impulse rotator in patients with vestibular schwannoma

Conclusion. Motorized head impulse rotator is an effective technique to assess peripheral vestibular function. Approximately a quarter of patients with vestibular schwannoma (VS) had preserved preoperative responses. Vestibular disability could not be predicted based on vestibulo-ocular reflex (VOR) performance during motion stimuli, or in the caloric test. Objectives. To explore motorized head impulse rotator for evaluation of angular horizontal VOR in patients with VS, and to compare these responses to those of the caloric test and the symptoms. Patients and methods. We prospectively recorded head and eye position during unpredictable motorized head impulses in 38 patients with VS. We calculated gain and asymmetry of VOR (mean±95% CI), and the results were compared to those of the caloric test and a questionnaire regarding dizziness, hearing and quality of life. Results. The VOR during motorized impulses was abnormal in 71% of patients. Asymmetry in gain correlated significantly (p<0.001) with unilateral weakness in the caloric test. Preoperative gain was significantly lowered to 0.83±0.08 on the ipsilateral side compared to 0.98±0.06 on the contralateral side. Postoperative gain on the operated side of 0.53±0.05 was significantly different from preoperative gain (p<0.001). Findings in vestibular tests did not correlate with subjective sensation of dizziness.     

Hearing deterioration in patients with a non-growing vestibular schwannoma

OBJECTIVE: The aim of this study was to document and analyse the course of several audiometric parameters in 49 patients with a non-growing unilateral vestibular schwannoma (VS). MATERIAL AND METHODS: Patients received conservative management and absence of tumour growth was ascertained by means of serial magnetic imaging studies. Pure-tone audiometry and speech audiometry were performed at yearly intervals. RESULTS: Pure-tone audiometry revealed a significant increase in thresholds at all frequencies, except for 8.0 kHz. The maximum yearly threshold increase was 2.4 dB hearing level at 1.0 and 2.0 kHz. Speech audiometry revealed a significant decrease in maximum discrimination over the course of time. No significant changes were observed in the following parameters: the intensity level at which maximum discrimination was achieved; the roll-over index; the speech reception threshold; and the slope of the curve in the speech audiogram. No change was observed in the relation between pure-tone audiometry thresholds and speech audiometry scores. Apparently, the deterioration of pure-tone perception and speech discrimination ran parallel courses. CONCLUSIONS: The results of this study indicate that hearing loss is a predominant symptom in patients with a non-growing VS, as is also known in patients with a growing lesion. Moreover, it seems unlikely that the hearing loss in VS patients is merely the result of mechanical influences on retrocochlear neural or vascular structures.     

Translabyrinthine surgery for disabling vertigo in vestibular schwannoma patients

Objective: To determine the impact of translabyrinthine surgery on the quality of life in vestibular schwannoma patients with rotatory vertigo. Study design: Prospective study in 18 vestibular schwannoma patients. Setting: The study was conducted in a multispecialty tertiary care clinic. Participants: All 18 patients had a unilateral intracanalicular vestibular schwannoma, without serviceable hearing in the affected ear and severely handicapped by attacks of rotatory vertigo and constant dizziness. Despite an initial conservative treatment, extensive vestibular rehabilitation exercises, translabyrinthine surgery was performed because of the disabling character of the vertigo, which considerably continued to affect the patients’ quality of life. Main outcome measures: Preoperative and postoperative quality of life using the Short Form 36 Health Survey (Short Form‐36) scores and Dizziness Handicap Inventory (DHI) scores. Results: A total of 17 patients (94%) completed the questionnaire preoperatively and 3 and 12 months postoperatively. All Short Form‐36 scales of the studied patients scored significantly lower when compared with the healthy Dutch control sample (P < 0.05). There was a significant improvement of DHI total scores and Short Form‐36 scales on physical and social functioning, role‐physical functioning, role‐emotional functioning, mental health and general health at 12 months after surgery when compared with preoperative scores (P < 0.05). Conclusions: Vestibular schwannoma patients with disabling vertigo, experience significant reduced quality of life when compared with a healthy Dutch population. Translabyrinthine tumour removal significantly improved the patients’ quality of life. Surgical treatment should be considered in patients with small‐ or medium‐sized tumours and persisting disabling vertigo resulting in a poor quality of life.     

Staged resection for vestibular schwannoma

Conclusion: Surgery remains the preferred option for large vestibular schwannoma (VS). The presence of unpredictable intraoperative difficulties may convince the operator to suspend the surgery to avoid risks to patient life. Additional surgeries may be mandatory and are better performed using a transcochlear approach. High rates of complications, poor facial nerve results, and a percentage of incomplete removals should be expected in such unfavorable cases. Objectives: To review the results for nine cases of huge VS treated by staged resection. Method: A retrospective case review was performed for all nine patients who underwent staged resection of VS at the Gruppo Otologico between 1984–2012. The decision to perform staged surgery was always made intra-operatively after encountering unpredicted difficulties. Results: The nine patients represented 0.3% of all patients who underwent VS surgery during the same period. Mean tumor size was 4.7 cm (range = 3.0–6.6 cm). Two cases required three surgeries, resulting in a total of 20 operations. In addition, two cases required pre-operative ventriculoperitoneal shunt and one required temporary tracheotomy. After the final stage of surgery, complete removal had been achieved in six of the nine patients. The facial nerve was never preserved anatomically.     

Results achieved in the treatment of patients with vestibular schwannoma

Personal experience gathered with the treatment of 264 vestibular schwannoma (VS) at the Magdeburg University ENT Hospital is analysed. ABR Audiometry is useful as a screening, even though it yielded false-negative values in 12.7% (n = 33) for intrameatal VS and 16.9% for all VS, despite accurate evaluation. Latency increases of Waves I, III and V and their intraaural comparison exhibited a statistically significant difference for the VS levels proposed by TOS. The mean of intrameatal VS too was found to have longer latencies compared with the normal-hearing ears of the patients. In the individual case, with threshold hearing normal, anamnestic findings as well as otoneurological evidence provide an early indication for enhanced MRI, CISS imaging, or individual 3D reconstruction of the pontocerebellar cisterna. Adopting intraoperative monitoring of the facial nerve and the cochlea as well as the Pars acustica by means of far-field and near-field electrodes, a good facial 'mobility' was achieved in 95.3%, and a useful audition (AAO-HNS Types A and B) in 60%. Monitoring is beneficial as it enhances the reliability and improves the subtle preparation during surgery. The power of hearing improved postoperatively within six months and remained at a good level over two years. From our perspective, otorhinolaryngologists are the right specialists to attend to VS.     

Surgical management of vestibular schwannoma in elderly patients

This study aimed to evaluate surgical results of vestibular schwannoma in elderly patients using a retrospective study in a Quaternary Neurotology and Skull Base Referral Center setting. The data of 232 elderly patients (above 65 years) operated on for vestibular schwannoma in the period between April 1987 and July 2009 were reviewed. Most patients were operated on via translabyrinthine approach (TLA) using transapical extension for large tumors. Other approaches used were retrosigmoid, middle cranial fossa, and transcochlear. Total tumor removal was achieved in the majority of cases, while planned subtotal removal was used in specific occasions. Postoperative complications included facial nerve palsy, other cranial nerves injury, persistent instability, intracranial hemorrhage, CSF leak, meningitis, and death. Patients were followed after surgery for tumor regrowth or occurrence of complications. The results showed low rate of morbidity and mortality. Despite that complete removal is the main target of the surgery; adoption of subtotal removal in selected cases can improve postoperative facial nerve results and reduce the duration of surgery.     

Abnormal deviation of subjective visual horizontal in patients with vestibular schwannoma

OBJECTIVES: This study was aimed to examine the correlation between the results of subjective visual horizontal (SVH) and other vestibular function tests in patients with untreated unilateral vestibular schwannoma (VS). METHODS: The subjects comprised 40 consecutive patients (17 men, 23 women) with VS who underwent vestibular function tests before surgery and had surgically and histopathologically confirmed unilateral VS. The vestibular function tests included SVH, caloric, and vestibular evoked myogenic potential (VEMP) tests. RESULTS: Of the 40 patients, 31 (77.5%) showed deviation of the SVH toward the affected side down. Especially in 8 patients (20.0%), abnormal deviation (more than 2.2 degrees) toward the affected side down was seen. None of the patients showed abnormal deviation toward the unaffected side down. On the caloric test, the proportion of absent caloric responses and the percent canal paresis in patients with an abnormal SVH was significantly higher than those in patients with a normal SVH. The proportion of abnormal VEMP responses was higher and the percent VEMP asymmetry was smaller in patients with an abnormal SVH than in patients with a normal SVH; however, the differences were not significant. CONCLUSIONS: Abnormal results on the caloric test and/or VEMP test were more frequently seen in VS patients with abnormal deviation of the SVH.     

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.     

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.     

Quality of life of vestibular schwannoma patients after surgery

The quality of life of vestibular schwannoma (VS) patients after surgery was investigated. The subjects consisted of 236 unilateral VS patients who underwent tumor removal between 1990 and 1997. A questionnaire was sent to all patients regarding their hearing, tinnitus, dizziness and the changes in their daily life after surgery; 176 out of 204 patients (86%) who received the questionnaire completed and returned it. The answers were compared with recent data reported in other clinical studies. Ninety percent of the patients with postoperative class A hearing were satisfied with their hearing. However, only 30% of patients with postoperative class B hearing were satisfied. Tinnitus worsened after surgery more often in patients who underwent a labyrinthectomy than in those who did not. Dizziness improved after surgery in the majority of VS patients. However, 30% of patients had difficulty driving a car and 50% of patients could not enjoy activities such as playing sport after surgery.     

Galvanic-induced body sway in vestibular schwannoma patients: evidence for stimulation of the central vestibular system

OBJECTIVE: To investigate the various possible sites of excitation by galvanic stimulation by comparing the galvanic-induced body sway (GBS) in vestibular schwannoma (VS) patients with that in healthy subjects. MATERIAL AND METHODS: This was a prospective experimental study conducted in a tertiary referral centre. In a previous study we developed a standardized procedure for reproducible quantification of GBS using a monaural continuous 1-cosinusoidal stimulus (0.5 Hz; 2 mA). In this study, 23 VS patients were tested before and 12 VS patients were also tested after surgical intervention (extirpation of tumour with concomitant vestibular neurectomy) and the results were compared with those obtained in 47 healthy subjects. RESULTS: There were no significant differences in mean total GBS gain between VS patients and healthy subjects (p>0.05) before surgical intervention. After vestibular neurectomy a significant difference in the mean total GBS gain was observed, but GBS was still present after surgery. CONCLUSION: These results prove that galvanic vestibular stimulation excites the central vestibular system even when conduction via the vestibular nerve is hampered.     

Comparison of electronystagmography results with dynamic posturography findings in patients with vestibular schwannoma

CONCLUSION: Condition-5-score (C5S) and condition-6-score (C6S) of computerized dynamic platform posturography (CDPP) can detect the presence of a functional deficit of the lateral semicircular canal (and the superior vestibular nerve), irrespective of the central vestibular compensatory status, in vestibular schwannoma (VS) patients. OBJECTIVES: To test whether CDPP findings differ between VS patients with and without asymmetry on caloric and/or rotational ENG studies. PATIENTS AND METHODS: This was a retrospective review of 216 consecutive patients with VS. C5S and C6S of CDPP (Equitest) were compared among patients with normal caloric and rotational studies, patients with asymmetry on caloric studies and normal rotational studies, and patients with asymmetric caloric and rotational studies using the Wilcoxon-Mann-Whitney test. RESULTS: C5S and C6S of VS patients with normal caloric and rotational studies were significantly higher than in VS patients with either asymmetry on both rotational and caloric test results (p<0.001 for both C5S and C6S) or normal rotational studies and asymmetry on caloric testing (p<0.001 for both C5S and C6S). Neither C5S nor C6S were significantly different between patients with asymmetry on caloric testing and normal rotational studies and patients with asymmetry on both rotational and caloric testing.