Reversible altered consciousness with brain atrophy caused by valproic acid.

A 5-year-old female developed alteration of consciousness during 3 days of long-term treatment with valproic acid for localization-related epilepsy. Computed tomography revealed cerebral atrophy, and electroencephalography presented slow background activity. Consciousness cleared only 12 hours after valproic acid was discontinued, and normal electroencephalography results were evident 1 week later. Cerebral atrophy was nonexistent 2 months later. This rapidly developing but reversible alteration of consciousness in parallel with brain atrophy is recognized as a rare idiosyncratic adverse effect of valproic acid.