Problems in interpreting abnormal auditory brainstem responses in comatose patients.

Auditory brainstem responses (ABRs) provide a way to evaluate central nervous system function in young, confused, uncooperative or comatose patients. Auditory brainstem responses represent activity in or around the vestibulocochlear (VIII) cranial nerve, cochlear nucleus, superior olivary complex, lateral lemniscus, and inferior colliculus. Many factors affect recording of the auditory brainstem response. These factors include technical factors, chronic alcoholism, demyelinating diseases, ototoxic drugs, barbiturates, hearing loss, otitis media, and hypothermia.