Cochlear Implantation in Vestibular Schwannoma: A Systematic Literature Review

Abstract

Objective Ipsilateral cochlear implantation (CI) in vestibular schwannoma (VS) has been an emerging trend over the last two decades. We conducted the first systematic review of hearing outcomes comparing neurofibromatosis 2 (NF2) and sporadic VS undergoing CI. A comparison of the two populations and predictor of outcome was assessed. This is an update to a previously presented study. Data Sources Systemic data searches were performed in PubMed NCBI and Scopus by an academic librarian. No restrictions based on the year of publication were used. Study Selection Studies were selected if patients had a diagnosis of NF2 and a CI placed in the affected side with reports of hearing outcome. Two independent reviewers screened each abstract and full-text article. Data Extraction Studies were extracted at the patient level, and the assessment of quality and bias was evaluated according to the National Institutes of Health Quality Assessment Tool. Main Outcome Measures Outcome predictors were determined by using the chi-square test and Student's t-test. Results Overall, most CI recipients functioned in the high-to-intermediate performer category for both sporadic and NF2-related VS. Median AzBio (Arizona Biomedical Institute Sentence Test) was 72% (interquartile range [IQR]: 50) in NF2 patients and 70% (IQR: 7.25) in sporadic patients. Larger tumor size predicted a poorer final audiometric outcome. Conclusions Categorization of hearing outcome into superior performance and inferior performance based on sentence recognition revealed a generally good hearing outcome regardless of treatment or patient population. Select patients with sporadic and NF2 VS may benefit from CI.

Functional Outcome After Simultaneous Vestibular Schwannoma Resection and Cochlear Implantation With Intraoperative Cochlear Nerve Monitoring

“…17,18 However, CI can only be provided if the CN function can be preserved. 6,19 While assessment of CN function has proven difficult in the past, the advent of intraoperative eABR measurements allowing meticulous monitoring of CN function has opened up plenty of opportunities to improve optimal screening and selection of patients eligible for CI.…”

“…Additionally, recent improvements in MRI sequencing and cochlear implant magnet design significantly reduce the severity of metal artifacts in MRI, which would normally hinder the appropriate postoperative tumor follow‐up with a cochlear implant in place 17,18 . However, CI can only be provided if the CN function can be preserved 6,19 . While assessment of CN function has proven difficult in the past, the advent of intraoperative eABR measurements allowing meticulous monitoring of CN function has opened up plenty of opportunities to improve optimal screening and selection of patients eligible for CI.…”

Cochlear Implantation Outcomes in Patients With Retrocochlear Pathology: A Systematic Review and Pooled Analysis

“…However, these reviews will often combine both operated and observed tumors, making outcome comparisons difficult. Tadokoro et al (63) reviewed CI in patients with VS and compared outcomes between sporadic and NF2-associated tumors. Fifty-six percent of tumors in their review had undergone resection before CI.…”

Cochlear Implant Outcomes between Patients with Sporadic and Neurofibromatosis Type 2–Associated Vestibular Schwannoma

“…The majority of CI outcome data in VS come from the NF2-related schwannomatosis (formerly neurofibromatosis type 2, hereafter referred to as “NF2”) literature (5). This is because subjects with NF2 often acquire bilateral nonserviceable hearing as a result of the disease process or treatment.…”

“…Cochlear implants (CIs) are one option to rehabilitate hearing in select patients with a sufficiently healthy intact cochlear nerve (2)(3)(4). Several studies have shown success with cochlear implantation in this population, generally with improved outcomes compared with auditory brainstem implantation (2)(3)(4)(5)(6). Although studies are limited, some have also stratified CI outcomes according to treatment modality to inform treatment algorithms for VS with long-term hearing in mind (2)(3)(4)(5)(6).…”