Consequences to hearing during the conservative management of vestibular schwannomas

Objective To estimate the risk of loss of serviceable hearing during the conservative management of vestibular schwannomas. Study Design: Retrospective case review. Methods: Twenty-five patients with a radiological diagnosis of unilateral vestibular schwannoma were managed conservatively for a mean duration of 43.8 months (range, 12-194 mo). The pure-tone average (PTA) (0.5, 1, 2, and 3 kHz) and speech discrimination scores (SDS) were measured at regular intervals throughout the entire duration of follow-up. Serviceable hearing was defined using two criteria: 70% SDS/30 dB PTA (the 70/30 rule) and 50% SDS/50 dB PTA (the 50/50 rule). The size and growth rate of tumors were determined according to the American Academy of Otolaryngology--Head and Neck Surgery guidelines (1995). Intervention was recommended if there was evidence of continuous or rapid radiological tumor growth, and/or increasing symptoms or signs suggestive of tumor growth, Results: The risk of loss of serviceable hearing for the total group was 43% using the 70/30 rule and 42% using the 50/50 rule. Tumor growth was considered significant (> 1 mm) in 8 tumors (32%) and nonsignificant in 17 (68%). The risk of loss of serviceable hearing for the tumor-growth group was 67% using the 70/30 rule and 80% using the 50/50 pule. In contrast, the risk of loss of serviceable hearing for the no tumor-growth group was 25% using the 70/30 rule and 14% using the 50/50 rule. No audiological factors predictive of tumor growth were identified. Conclusions: There is a significant risk of loss of serviceable hearing during the conservative management of vestibular schwannomas. This risk appears to be greater in tumors that demonstrate significant growth.