Successful treatment of Wernicke's encephalopathy in a boy with acute mixed lineage leukemia.

A 12-year-old boy had been treated with multiagent chemotherapy for acute mixed lineage leukemia and with intravenous hyperalimentation due to persistent diarrhea and vomiting for 2 months. He suddenly complained of horizontal nystagmus and gait disturbance followed by oculomotor palsy and disorientation within a few days. Blood tests revealed low serum vitamin B1 and high serum pyruvate. Magnetic resonance imaging in T2-weighted axial image revealed a high signal inside the bilateral thalami, mamillary bodies and periaquaductal gray matter. He was diagnosed as Wernicke's encephalopathy and successfully treated with vitamin B1. Careful observation and adequate treatment are emphasized in the management of this preventable and curable disease.