Ipsilateral and Contralateral Acoustic Brainstem Response Abnormalities in Patients With Vestibular Schwannoma

Abstract

OBJECTIVE: To analyze auditory brainstem response (ABR) data in patients with vestibular schwannomas (VS) in an effort to identify correlations between abnormal ABR parameters and tumor size. STUDY DESIGN: Cross-sectional study with chart review. SETTING: Tertiary referral hospital. SUBJECTS AND METHODS: Retrospective chart review and analysis of bilateral ABR records in patients with VS. Interaural latency differences of interpeak I-V (ILD-I-V) and ILD-V longer than 0.2 ms were used as abnormal criteria. RESULTS: Thirty patients with a mean age of 50 ± 14 years were included in this study. The most frequent changes in ABR parameters included those of ILD-I-V (100%), wave V latency (96.7%), ILD-V (93.3%), and interpeak I-V latency (90%). Average VS tumor size was 2.48 ± 1.31 cm. For patients with VS greater than or equal to 2 cm, the prevalences of abnormal ipsilateral interpeak III-V latency, contralateral wave V latency, and interpeak III-V latency showed statically significant differences ( P = 0.0035, P = 0.0267, and P = 0.0273, respectively) compared to those in patients with VS less than 2 cm. Tumor size was positively correlated with pure-tone average ( P = 0.0106) and with the total number of bilateral abnormal ABR parameters ( P = 0.004). CONCLUSIONS: We identified a correlation between ABR parameters and VS tumor size. An ipsilateral ILD-I-V greater than 0.2 ms was sensitive for detecting VS. Abnormal contralateral wave V and interpeak III-V latency indicated a tumor size potentially larger than 2 cm. Further studies are needed to confirm these findings.