Elevated pitch perception owing to carbamazepine-activating effect on the peripheral auditory system: auditory brainstem response study.

Auditory disturbance is an uncommon side effect of carbamazepine, the pathophysiologic mechanism of which has not been clearly elucidated. We performed an auditory brainstem response study in a 9-year-old boy with epilepsy who had suffered from falsely higher pitch perception immediately after the start of carbamazepine treatment. The auditory brainstem response results showed that both the peak latency of wave V and the interpeak latencies of waves I to V were significantly prolonged with 85 dB HL click stimulation and that the peak amplitudes of the waves were noticeably elevated, particularly with lower click stimulation intensity. Although it has been shown that carbamazepine has a suppressive effect on the central nervous system, these auditory brainstem response findings might constitute evidence of a carbamazepine-activating effect on the peripheral auditory system, which probably increased the sensitivity to low-pitched sounds, causing the development of falsely higher pitch perception in our patient.