Intraoperative Cochlear Nerve Monitoring for Vestibular Schwannoma Resection and Simultaneous Cochlear Implantation in Neurofibromatosis Type 2: A Case Series.

BACKGROUND: Neurofibromatosis type 2 (NF2) often results in profound hearing loss and cochlear implantation is an emerging hearing rehabilitation option. However, cochlear implant (CI) outcomes in this population vary, and intraoperative monitoring to predict cochlear nerve viability and subsequent outcomes is not well-established. OBJECTIVE: To review the use of intraoperative electrically evoked cochlear nerve monitoring in patients with NF2 simultaneous translabyrinthine (TL) vestibular schwannoma (VS) resection and cochlear implantation. METHODS: A retrospective review was performed of 3 patients with NF2 that underwent simultaneous TL VS resection and cochlear implantation with electrical auditory brainstem response (eABR) measured throughout tumor resection. Patient demographics, preoperative assessments, surgical procedures, and outcomes were reviewed. RESULTS: Patients 1 and 3 had a reliable eABR throughout tumor removal. Patient 2 had eABR pretumor removal, but post-tumor removal eABR presence could not be reliably determined because of electrical artifact interference. All patients achieved auditory percepts upon CI activation. Patients 1 and 2 experienced a decline in CI performance after 1 yr and after 3 mo, respectively. Patient 3 continues to perform well at 9 mo. Patients 2 and 3 are daily users of their CI. CONCLUSION: Cochlear implantation is attainable in cases of NF2-associated VS resection. Intraoperative eABR may facilitate cochlear nerve preservation during tumor removal, though more data and long-term outcomes are needed to refine eABR methodology and predictive value for this population.

Cochlear Implant Outcomes Following Vestibular Schwannoma Resection: Systematic Review.

OBJECTIVE: Hearing loss remains a significant morbidity for patients with vestibular schwannomas (VS). A growing number of reports suggest audibility with cochlear implantation following VS resection; however, there is little consensus on preferred timing and cochlear implant (CI) performance. DATA SOURCES: A systematic literature search of the Ovid Medline, Embase, Scopus, and clinicaltrails.gov databases was performed on 9/7/2018. PRISMA reporting guidelines were followed. STUDY SELECTION: Included studies reported CI outcomes in an ear that underwent a VS resection. Untreated VSs, radiated VSs, and CIs in the contralateral ear were excluded. DATA EXTRACTION: Primary outcomes were daily CI use and attainment of open-set speech. Baseline tumor and patient characteristics were recorded. Subjects were divided into two groups: simultaneous CI placement with VS resection (Group 1) versus delayed CI placement after VS resection (Group 2). DATA SYNTHESIS: Twenty-nine articles with 93 patients met inclusion criteria. Most studies were poor quality due to their small, retrospective design. Group 1 had 46 patients, of whom 80.4% used their CI on a daily basis and 50.0% achieved open-set speech. Group 2 had 47 patients, of whom 87.2% used their CI on a daily basis and 59.6% achieved open-set speech. Group 2 had more NF2 patients and larger tumors. CI timing did not significantly impact outcomes. CONCLUSIONS: Audibility with CI after VS resection is feasible. Timing of CI placement (simultaneous versus delayed) did not significantly affect performance. Overall, 83.9% used their CI on a daily basis and 54.8% achieved open-set speech.