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. © 2009 American Academy of Otolaryngology-Head and Neck Surgery Foundation.