Unilateral Multifocal Inner Ear and Internal Auditory Canal or Cerebellopontine Angle Cochleovestibular Schwannomas-Genetic Analysis and Management by Surgical Resection and Cochlear Implantation.

OBJECTIVE: To describe the genetic characteristics and the management of two very rare cases of unilateral multifocal inner ear and internal auditory canal or cerebellopontine angle cochleovestibular schwannomas not being associated to full neurofibromatosis type 2-related schwannomatosis. PATIENTS: In a 29-year-old man and a 55-year-old woman with single-sided deafness multifocal unilateral cochleovestibular schwannomas were surgically resected, and hearing was rehabilitated with a cochlear implant (CI). Unaffected tissue was analyzed using next generation sequencing of the NF2 gene. Tumor tissue was analyzed using a 340-parallel sequencing gene panel. MAIN OUTCOME MEASURES: Mutations in the NF2 gene, word recognition score for monosyllables at 65 dB SPL (WRS 65 ) with CI. RESULTS: No disease-causing mutation was detected in the examined sequences in blood leucokytes. All tumor samples revealed, among others, somatic pathogenic NF2 mutations. While the anatomically separate tumors in case 1 were likely molecular identical, the tumors in case 2 showed different genetic patterns. WRS 65 was 55% at 6 years of follow-up and 60% at 4.5 years of follow-up, respectively. CONCLUSIONS: The occurrence of multifocal unilateral cochleovestibular schwannomas without pathogenic variants in NF2 in non-affected blood leucocytes can be associated with mosaic NF2 -related schwannomatosis (case 1), or with likely sporadic mutations (case 2) and may be overlooked due to their extreme rarity. Although challenging, successful hearing rehabilitation could be achieved through surgical resection of the tumors and cochlear implantation.

Metabolic reprogramming of inner ear cell line HEI-OC1 after dexamethasone application.

INTRODUCTION: One approach to dampen the inflammatory reactions resulting from implantation surgery of cochlear implant hearing aids is to embed dexamethasone into the matrix of the electrode carrier. Possible side effects for sensory cells in the inner ear on the metabolomics have not yet been evaluated. OBJECTIVE: We examined changes in the metabolome of the HEI-OC1 cell line after dexamethasone incubation as a cell model of sensory cells of the inner ear. RESULTS AND CONCLUSION: Untargeted GC-MS-profiling of metabolic alterations after dexamethasone treatment showed that dexamethasone had antithetical effects on the metabolic signature of the cells depending on growth conditions. The differentiated state of HEI-OC1 cells is better suited for elucidating metabolic changes induced by external factors. Dexamethasone treatment of differentiated cells led to an increase in intracellular amino acids and enhanced glucose uptake and ß-oxidation in the cells. Increased availability of precursors for glycolysis and ATP production by ß-oxidation stabilizes the energy supply in the cells, which could be assumed to be beneficial in coping with cellular stress. We found no negative effects of dexamethasone on the metabolic level, and changes may even prepare sensory cells to better overcome cellular stress following implantation surgery.

How Much Cochlea Do You Need for Cochlear Implantation?

OBJECTIVE: To assess the efficacy of cochlear implantation (CI) after surgical removal of sporadic intracochlear or intravestibulocochlear schwannomas. STUDY DESIGN: Nonconcurrent cohort study. SETTING: Monocentric study at a tertiary referral center. PATIENTS: Patients with tumor resection and CI between 2011 and 2018 and a historic control group of CI patients matched by age, CI electrode type, and follow-up. INTERVENTIONS: Partial or subtotal cochleoectomy for tumor removal and single-stage CI. OUTCOME MEASURES: Main outcome measure: word recognition score for monosyllables in quiet at 65 dB SPL. RESULTS: Sixteen patients with tumor removal and CI (6 female, 10 male; mean age 55 ±â€Š14 years) and 16 control patients (6 female, 10 male; mean age 55 ±â€Š15 years) were identified. In the tumor group, surprisingly good word recognition scores were reached even after substantial structural defects in the cochlear capsule. While 12 months after cochlear implantation mean word recognition score for monosyllables in quiet was 58% (SD: 26) and 41% (SD: 26) in the control groups, it was 75% (SD: 19%) in the tumor group. CONCLUSIONS: In patients with intracochlear schwannomas, despite substantial structural damage to the cochlear capsule by partial or subtotal cochleoectomy, a tendency toward better performance with respect to word recognition with CI was observed as compared with other CI patients. The surprisingly good functional results despite substantial cochlear trauma may change clinical thinking with respect to cochlear implantation also beyond this special indication.