A patient with type II citrullinemia who developed refractory complex seizure.

A 31-year-old Japanese male was admitted to our hospital for refractory complex seizures. He had no history on medical or psychiatric illness. He began to exhibit aberrant behavior accompanied by cloudiness of consciousness. Thereafter, he exhibited partial seizures followed by a twilight state or abnormal behavior. Previous treatment with valproate and carbamazepine failed to improve his seizures. Because an increase in plasma ammonia was noted, anticonvulsant was discontinued within a week. He was then transferred to our department. Blood examination revealed an increase in ammonia. Amino acid analysis demonstrated a marked increase in citrulline and decrease in arginine. He was diagnosed with type II citrullinemia. After being treated with arginine hydrochloride, the seizures and disturbed consciousness improved. He was then discharged, and remains in remission. Accumulations of citrulline and ammonia and a reduction of arginine are noted in argininosuccinate synthetase deficiency, which results in the sudden emergence of consciousness disturbance and abnormal behavior. It is essential to examine amino acid levels as well as ammonia levels in patients with unexplained neuropsychiatric symptoms, especially those with altered consciousness levels and seizures.