Cochlear implantation after radiosurgery for vestibular schwannoma

The object of this study was to ascertain outcomes of cochlear implantation (CI) following stereotactic radiosurgery (SRS) for vestibular schwannoma (VS).

The authors conducted a retrospective chart review of adult patients with VS treated with SRS who underwent CI between 1990 and 2019 at a single tertiary care referral center. Patient demographics, tumor features, treatment parameters, and pre- and postimplantation audiometric and clinical outcomes are presented.

Seventeen patients (18 ears) underwent SRS and ipsilateral CI during the study period. Thirteen patients (76%) had neurofibromatosis type 2 (NF2). Median age at SRS and CI were 44 and 48 years, respectively. Median time from SRS to CI was 60 days, but notably, 4 patients underwent SRS and CI within 1 day and 5 patients underwent CI more than 7 years after SRS. Median marginal dose was 13 Gy. Median treatment volume at the time of SRS was 1400 mm3 (range 84-6080 mm3, n = 15 patients). Median post-CI PTA was 28 dB HL, improved from 101 dB HL preoperatively (p < 0.001). Overall, 11 patients (12 ears) exhibited open-set speech understanding. Sentence testing was performed at a median of 10 months (range 1-143 months) post-CI. The median AzBio sentence score for patients with open-set speech understanding was 76% (range 19%-95%, n = 10 ears). Two ears exhibited Hearing in Noise Test (HINT) sentence scores of 49% and 95%, respectively. Four patients achieved environmental sound awareness without open-set speech recognition. Two had no detectable auditory percepts.

Most patients who underwent CI following SRS for VS enjoyed access to sound at near-normal levels, with the majority achieving good open-set speech understanding. Implantation can be performed immediately following SRS or in a delayed fashion, depending on hearing status as well as other factors. This strategy may be applied to cases of sporadic or NF2-associated VS.

AAO-HNS = American Academy of Otolaryngology-Head and Neck Surgery; ABI = auditory brainstem implant; CI = cochlear implantation; CN = cranial nerve; CNC = consonant-nucleus-consonant; CPA = cerebellopontine angle; EPS = electrical promontory stimulation; ESA = environmental sound awareness; HINT = Hearing in Noise Test; IAC = internal auditory canal; NF2 = neurofibromatosis type 2; OSP = open-set speech perception; PTA = pure tone average; SRS = stereotactic radiosurgery; VS = vestibular schwannoma; WRS = word recognition score.