A 58-year-old male with severe developmental delay, convulsive seizure disorder since the age of three, left hemiparesis, recurrent aspiration pneumonia, and urinary retention presented for evaluation of hypothermia. Over the preceding year, he had experienced nine hypothermic episodes, with temperatures ranging from 90  F-95  F (Fig. 1). The hypothermia was usually thought to be secondary to infection. Upon presentation, his temperature was 92  F at his group home and 95  F in the office.
The patient, who was noncommunicative at baseline, was hospitalized and on examination appeared awake with no distress, calmly sitting in his wheelchair. He is normally hyperactive, but his caregivers noticed he would become listless during his hypothermic episodes. His blood pressure was 138/74 mmHg, pulse was 59 beats per minute, and oxygen saturation was 96%. The patient's lungs were clear to auscultation, and his heartbeat had a normal rate and rhythm, with no murmurs. He had full visual fields, intact extraocular movements, no nystagmus, pupils equal and reactive to light, and a midline tongue. He also had a left facial droop, increased spastic tone in the left arm and leg, and intact reflexes, but sensation and strength could not be tested.
Bair Hugger therapy, a forced air warming blanket, successfully raised the patient's temperature to 97  F, which was maintained after it was removed. Empiric cephalexin and ciprofloxacin were started to treat any potential infectious etiology of temperature dysregulation. However, a urinalysis and chest X-ray were both unremarkable, and cultures remained negative, so antibiotics were discontinued on hospital day two. TSH and cortisol levels were normal.
Additional past medical history included hyponatremia, hypertension, cyclothymia, renal cell carcinoma, iron deficiency, thrombocytopenia, osteoporosis, and gastroesophageal reflux disease. The patient was taking phenytoin (200 mg/day), levetiracetam (3000 mg/day), and clobazam (10 mg bid) for seizures, amlodipine (10 mg/day) for hypertension, quetiapine (100 mg/day) and fluoxetine (30 mg/day) for cyclothymia, clonazepam (1 mg/day) for behavior, and aspirin (81 mg/day). He had previously taken oxcarbazepine for epilepsy but switched to clobazam because of hyponatremia. Clobazam had been started one year prior, and it was the last drug added. Because of this and the fact that clobazam had been recently linked to hypothermia, the drug was tapered from 10 to 5 mg bid over one week. During this period, the patient experienced one more hypothermic episode. Clobazam was then discontinued after this week, and since then, there have been no episodes of hypothermia for over half a year.