No abstract

Objective: No previous studies have investigated a vestibular function test battery combining the Video Head Impulse Test (VHIT), the caloric test, and the cervical vestibular evoked myogenic potential (cVEMP) test. The objective was to investigate the sensitivity of the three vestibular tests to the presence of a vestibular schwannomas (VS), and possible correlations between test results, hearing acuity, and tumor size. Study Design: Retrospective cohort study. Setting: University hospital. Patients: Fifty-nine patients with a unilateral VS. Intervention: Audio-vestibular tests; the VHIT, cVEMP, caloric irrigation, pure-tone audiometry, and speech discrimination. Main Outcome Measure: Findings, sensitivity, and correlations between VHIT saccades and gain; cVEMP potentials, unilateral caloric weakness; hearing acuity. Results: The sensitivity for VS was 80% for the VHIT, 93% for the caloric test, and 73% for the cVEMP test. VHIT gain and saccades were associated, and both had a positive correlation to caloric function. Medium-sized tumors demonstrated the highest gain asymmetry while larger tumors were associated with saccades. There was a weak correlation between vestibular findings and hearing acuity. Conclusion: The VHIT is sensitive to the occurrence of a VS, but less so than the caloric test, and vestibular function deteriorates to some extent with increasing tumor size. VHIT outcomes are positively correlated to caloric function, but only vaguely to cVEMP and hearing acuity. The combined vestibular function test battery reached a sensitivity of 97% to the occurrence of a VS and could thus potentially substitute MRI for tumor screening upon the diagnosis of an asymmetrical hearing loss.

In light of missing systematic reviews in the literature, the objective of this paper is to present the contemporary knowledge on the molecular biology of vestibular schwannomas (VS), based on a systematic literature search. In addition, current and prospected medical therapy based on molecular biology is addressed. A systematic literature search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The systematic search was performed in the Pubmed and Embase databases. The following were the words searched: acoustic neuroma/vestibular schwannoma, molecular biology, gene, and microRNA. Specific inclusion and exclusion criteria were determined prior to search. The systematic search rendered 486 articles, ultimately yielding 69 included articles, whereas 35 were from relevant references. The occurrence of at least one mutation in the merlin gene was reported to range between 54% and 76%, whereas the loss of heterozygosity (LOH) corresponding to chromosome 22 occurs in 25% to 83% of sporadic VS. Global gene expression studies indicate that a number of genes other than merlin are at play. No high-level methylation of the merlin gene has been found. Several miRNAs are deregulated in tumor tissue, among others let-7d, miR-221, and miR-21. The acquired knowledge on molecular biology has led to several clinical implementations. Lack of the tumor suppressor merlin plays a principal role in the development of VS. Existing knowledge on the molecular biology has led to the first attempts of targeted medical treatment to prevent tumor growth. Future research is likely to introduce potential imaging markers with prognostic value and new targets for medical therapy.

Objective: To report hearing preservation results after retrolabyrinthine vestibular schwannoma surgery, using a new system for continuous near real-time monitoring of cochlear nerve function. Study Design: Retrospective chart review. Setting: Tertiary referral center, University Hospital. Patients: Thirty-one consecutive patients with growing vestibular schwannomas and opting for hearing preservation surgery. Interventions: Tumor removal by a modified, extended retrolabyrinthine approach, using a new system for continuous near real-time monitoring of cochlear nerve function. Main Outcome Measures: Pure-tone average and speech discrimination (SD) 1-year postoperative. Preservation of word recognition score class. Preservation of serviceable hearing (SD>50%). Results: Any hearing was preserved in 83 and 69% had preserved word recognition score class or better. Serviceable hearing was preserved in 77%. SD was unchanged in 48%, improved in 21%, and poorer in 31%. Of 18 patients with potential for improvement (SD 90% or worse preoperatively), 33% improved (SD increase 10% or more). Conclusion: The hearing preservation rate is favorable using the modified, extended retrolabyrinthine approach and a new system for continuous near real-time monitoring of cochlear nerve function for removal of growing vestibular schwannomas, as 77% preserved serviceable hearing 1 year after surgery. Hearing improved after surgery in 33%. Using the new neuromonitoring system, serviceable hearing preservation rate improved from 53 to 77% at our center.