Paroxysmal sympathetic storms ("diencephalic seizures") after severe diffuse axonal head injury.

We describe a patient with a severe traumatic head injury who exhibited paroxysmal sympathetic storms, similar to those described in "diencephalic seizures." No epileptiform activity was evident on electroencephalography, and therapeutic levels of anticonvulsants failed to alter the spells; however, use of morphine sulfate abolished them. The features of this and several previously reported cases refute the primary roles of the diencephalon and seizures in this syndrome. Rather, in the setting of already compromised autonomic neuronal integrity, subtle fluctuations in intraventricular pressure or activation of reflexes triggered from muscle mechanoreceptors or chemoreceptors during episodes of hypertonia are more likely. "Paroxysmal sympathetic storms," a more appropriate descriptive term for these phenomena, should be recognized; thus, unnecessary diagnostic evaluations can be minimized, and appropriate therapy can be initiated.