Episodes of paroxysmal sympathetic hyperactivity, sometimes referred to as autonomic storms, are not uncommon in patients with severe traumatic brain injury. Their distinctive characteristics include fever, tachycardia, hypertension, tachypnea, hyperhidrosis, and dystonic posturing. The episodes may be induced by stimulation or may occur spontaneously. Their pathophysiology has not been fully elucidated, but the manifestations clearly indicate activation or disinhibition of sympathoexcitatory areas. These spells are often confused with seizures, leading to unnecessary treatment with antiepileptic drugs. General principles in the management of paroxysmal sympathetic hyperactivity include adequate hydration, exclusion of mimicking conditions (infection, pulmonary embolism, hydrocephalus, epilepsy), effective analgesia, and avoidance of triggers, when identified. The most useful pharmacologic agents are morphine sulfate and nonselective beta-blockers (eg, propranolol). Intrathecal baclofen may be effective in refractory cases. Bromocriptine and clonidine are helpful in some patients, but their efficacy is less consistent. Early recognition and adequate treatment of paroxysmal sympathetic hyperactivity is important to avoid prolongation of the patient's stay in the intensive care unit and to enable recovering patients to participate without restrictions in rehabilitation therapy.