Deafness after bilateral midbrain contusion: a correlation of magnetic resonance imaging with auditory brain stem evoked responses.

A 46-year-old woman became deaf after a closed head injury. When a computed tomographic scan failed to disclose the cause, conversion disorder was suspected. Magnetic resonance imaging, however, showed bilateral contusions of the inferior colliculi, providing objective evidence for an organic cause of hearing loss. Auditory brain stem evoked responses and stapedial reflexes also provided objective evidence of brain stem injury. This case illustrates the phenomenon of dorsal midbrain injury after head trauma. It indicates the sensitivity of magnetic resonance imaging for small focal lesions after head trauma, and it demonstrates some difficulties in the diagnosis of "hysterical" deafness.