[Successful treatment using low-dose carbamazepine for a patient of personality change after mild diffuse brain injury].

A 19-year-old male had a traffic accident while driving his motorbike and suffered an injury to the left frontotemporal part of the head. He remained conscious, had no focal neurological signs, and brain-computed tomography was unremarkable at the prefectural hospital, department of neurosurgery. Six months later he demonstrated a personality change, which was marked by irritability, aggression, labile moods, childishness, irresponsibility, and a lack of motivation. He sometimes made trouble for those around him, and he consulted our hospital 2 years and 9 months after the accident. He was diagnosed as having posttraumatic personality disorder and was treated with clonazepam, a dosage of up to 1.5 mg/day. Although his symptoms were moderately improved, he complained of sleepiness as an adverse effect. Carbamazepine (100 mg/day) was added in expectation of further improvement. Within a few days he improved to his preaccident personality. After the administration of clonazepam was discontinued, he maintained his good mental status. Now about two years after the initiation of therapy, he works in social welfare facilities and has no relapses. Even if a head injury is mild without definite organic signs in brain, it may have a possibility of causing personality change, which may be treatable.