Decerebrate posturing with the syndrome of inappropriate secretion of antidiuretic hormone.

Decerebrate and/or decorticate posturing have not yet been described as possible features of the syndrome of inappropriate secretion of antidiuretic hormone. Cerebral edema and loss of brain electrolytes are contributing factors resulting in altered excitability of the neural membrane. We describe a patient who, on the eighth day after a head injury, presented with decerebrate posturing, which coincided with the development of the syndrome of inappropriate secretion of antidiuretic hormone, and which rapidly reversed with the correction of the hyponatremia. We believe that the syndrome of inappropriate secretion of antidiuretic hormone should be included in the differential diagnosis of abnormal posturing in the head-injured patient.