A 46-year-old man had recurrent episodes of diffuse hyperhidrosis and hypothermia (Video 1) lasting approximately 20 minutes for 20 days. His temperature was 35.4°C, blood pressure was 159/101 mm Hg, heart rate was 120/min, and diffuse hyperhidrosis was the only neurologic sign during an episode. Seizures were considered, but EEG during an episode was normal. MRI showed corpus callosum agenesis (Figure). He was diagnosed with Shapiro syndrome, which may be due to hypothalamic dysfunction and is responsive to clonidine and carbamazepine.1,2 Because of lack of clonidine and hyponatremia, the patient was treated with levetiracetam, and the episodes disappeared after 5 days.