Auditory brainstem response abnormalities in adductor spasmodic dysphonia.

Six patients with adductor spasmodic dysphonia were evaluated for evidence of brainstem dysfunction using the auditory brainstem response (ABR). In four, abnormally large increments in wave V latencies were found at high stimulus repetition rates. Latency increments exceeded three standard deviations above the mean in a normative adult population. A fifth patient had the prolonged interpeak latencies described previously by other investigators. In five of six patients the capacity of the auditory brainstem to conduct impulses was compromised. These results suggest a central nervous system abnormality in adductor spasmodic dysphonia.