Hearing improvement after vestibular schwannoma surgery in the era of the hearing preservation rule - case report and literature review.

OBJECTIVES: Hearing preservation after vestibular schwannoma (VS) surgery remains a surgical challenge. In some patients with preserved inner ear function, hearing improvement is achievable. As it is currently impossible to determine which patients will present this outcome, predictions must rely on previously published reports. Our case report describes a patient who experienced hearing improvement from an unuseful level to a useful one after vestibular schwannoma surgery. METHODS: Surgery was performed via suboccipital retrosigmoid approach. The patient underwent a basic audiovestibular protocol before and after the surgery - pure tone and speech audiometry, otoacoustic emissions, auditory brainstem responses, electronystagmography - together with a detailed questionnaire study. Usefulness of hearing was evaluated using the AAO-HNS guidelines, supplemented by a frequency of 4 kHz. RESULTS: Hearing was preserved and even improved from an unuseful level to a useful one. Based on the available literature, the most informative predictive factors for such a result seem to be: sudden sensorineural hearing loss prior to surgery, elicitable otoacoustic emissions and the origin from the superior vestibular nerve. CONCLUSION: There are a limited number of studies on this topic and it is still impossible to regularly improve hearing in properly selected patients. Furthermore, the importance of postoperative hearing quality compared to other symptoms and complications remains debatable.

Assessment of visual sensation, psychiatric profile and quality of life following vestibular schwannoma surgery in patients prehabituated by chemical vestibular ablation.

AIMS: Preoperative chemical vestibular ablation can reduce vestibular symptoms in patients who have gone through vestibular schwannoma resection. The goal of this study was to determine whether chemical vestibular prehabituation influences the patients' post-operative perception of visual stimulation, mental status and quality of life. We also tried to find out whether increases of optokinetic nystagmus, measured by routine electronystagmography, correlate with subjective symptoms. METHODS: We preoperatively administered (2 months prior to surgery) 0.5 - 1.0 mL of 40 mg/mL nonbuffered gentamicin in three intratympanic instillations in 11 patients. Head impulse and caloric tests confirmed reduction of vestibular function in all patients. The control group consisted of 21 patients. Quality of life in both groups was evaluated using the Glasgow Benefit Inventory, the Glasgow Health Status Inventory and the Dizziness Handicap Inventory questionnaires. Visual symptoms and optokinetic sensation were evaluated using a specific questionnaire developed by our team and by measuring gains preoperatively and postoperatively in both groups using routine electronystagmography. The psychological profile was evaluated using the Zung Self-Rating Depression Scale and the Generalised Anxiety Disorder Assessment questionnaires. RESULTS: There were no statistically significant differences between both groups with regards to the results of the questionnaires. Patients who received preoperative gentamicin were less sensitive to visual stimulation (P<0.10) and many of them had a significantly higher gain in the optokinetic nystagmus than the control group in the preoperative stage. CONCLUSION: Pre-treatment with gentamicin helps to lower anxiety levels in patients and improves their general postoperative status. Pre-treated patients are also less sensitive to optokinetic stimulation. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03638310.

Moderate sensorineural hearing loss is typical for DFNB16 caused by various types of mutations affecting the STRC gene.

INTRODUCTION: Hearing loss is the most frequent sensory disorder and is genetically extremely heterogeneous. By far the most frequent cause of nonsyndromic autosomal recessive hearing loss (AR-NSHL) are biallelic pathogenic mutations in the GJB2 gene causing DFNB1. The worldwide search for the second most common type of AR-NSHL took almost two decades. Recently reported alterations (mostly deletions) of the STRC gene, also named DFNB16, seem to be the second most frequent cause of AR-NSHL. Genetic testing of STRC is very challenging due to the highly homologous pseudogene. Anecdotal evidence from single patients shows that STRC mutations have their typical audiological findings and patients usually have moderate hearing loss. The aim of this study is to discover if audiological findings in patients with biallelic pathogenic mutations affecting STRC have the characteristic features and shape of audiological curves and if there are genotype/phenotype correlations in relation to various types of STRC mutations. METHODS: Eleven hearing loss patients with pathogenic mutations on both alleles of the STRC gene were detected during routine genetic examination of AR-NSHL patients. Audiological examination consisted of pure tone audiometry, stapedial reflexes, tympanometry and otoacoustic emission tests. RESULTS: The threshold of pure tone average (PTA) was 46 dB and otoacoustic emissions were not detectable in these DFNB16 patients. All patients were without vestibular irritation or asymmetry. CONCLUSION: Moderate sensorineural hearing loss is typical for DFNB16-associated hearing loss and there are no significant differences in audiological phenotypes among different types of mutations affecting STRC.

The evaluation of vestibular compensation by vestibular rehabilitation and prehabilitation in short-term postsurgical period in patients following surgical treatment of vestibular schwannoma.

PURPOSE: Vestibular schwannoma removal causes unilateral vestibular deafferentation, which results in dizziness and postural unsteadiness. Vertigo and balance problems together are among the most important aspects affecting quality of life. Intensive vestibular rehabilitation, which starts before surgery, with following postsurgical supervised rehabilitation, using visual biofeedback propose an instrument to accelerate a recovery process. Another option how to accelerate the vestibular compensation, is employment of presurgical gentamicin ablation together with vestibular rehabilitation (prehabilitation) of vestibular function. Purpose of present study was to examine the dynamics of vestibular compensation process using supervised intensive vestibular rehabilitation with visual biofeedback in the short-term postsurgical period. The second aim was to compare both studied groups mainly to evaluate if prehabilitation has potential to accelerate the compensation process in the early postoperative course. METHODS: The study included 52 patients who underwent the retrosigmoid vestibular schwannoma removal. They were divided into two groups. The first group was prehabilitated with intratympanic application of gentamicin before surgery to cause unilateral vestibular loss (14 patients), the second group (38 patients) was treated in standard protocol without prehabilitation. All patients underwent at home vestibular training before surgery to learn new movement patterns. Following the surgery supervised intensive vestibular rehabilitation including visual biofeedback was employed daily in both groups between the 5th and 14th postoperative day. Outcome measurements included an evaluation of subjective visual vertical (SVV), posturography and the Activities-Specific Balance Confidence Scale (ABC). ANOVA for repeated measurements was used for statistical analysis. RESULTS: We observed significant improvement in SVV (p < 0.05), posturography parameters (p < 0.05) and ABC scores (p < 0.05) with postoperative rehabilitation program following surgery in both groups. There was no statistically significant difference between group treated by prehabilitation and group without prehabilitation. CONCLUSIONS: Results of this study showed that intensive postsurgical rehabilitation represents key factor in compensation process following retrosigmoid vestibular schwannoma surgery. Prehabilitation did not speed up recovery process.

Vertigo Perception and Quality of Life in Patients after Surgical Treatment of Vestibular Schwannoma with Pretreatment Prehabituation by Chemical Vestibular Ablation.

Surgical removal of vestibular schwannoma causes acute vestibular symptoms, including postoperative vertigo and oscillopsia due to nystagmus. In general, the dominant symptom postoperatively is vertigo. Preoperative chemical vestibular ablation can reduce vestibular symptoms postoperatively. We used 1.0 mL of 40 mg/mL nonbuffered gentamicin in three intratympanic installations over 2 days, 2 months preoperatively in 10 patients. Reduction of vestibular function was measured by the head impulse test and the caloric test. Reduction of vestibular function was found in all gentamicin patient groups. After gentamicin vestibular ablation, patients underwent home vestibular exercising for two months. The control group consisted of 10 patients who underwent only home vestibular training two months preoperatively. Postoperative rates of recovery and vertigo in both groups were evaluated with the Glasgow Benefit Inventory (GBI), the Glasgow Health Status Inventory (GHSI), and the Dizziness Handicap Inventory questionnaires, as well as survey of visual symptoms by specific questionnaire developed by us. There were no statistically significant differences between both groups with regard to the results of questionnaires. Patients who received preoperative gentamicin were more resilient to optokinetic and optic flow stimulation (p < 0.05). This trial is registered with clinical study registration number NCT02963896.