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The patient is a 19-year-old man who was in a motor vehicle collision and was brought to the emergency department for management of traumatic brain injury. On arrival he was Glasgow Coma Scale (GCS) of 5. A computed tomography (CT) scan showed diffuse cerebral edema. An intracranial pressure (ICP) monitor was placed, and he had aggressive medical measures to control ICP. By hospital day 7 his ICPs are under control. On day 14 he develops episodes of tachycardia, increased respiratory rate, fever, diaphoresis, and dystonic posturing occurring 8 to 10 times per day. Vital signs are temperature, 38.9°C; heart rate, 130 bpm; respiratory rate, 32 breaths/min; and blood pressure, 180/75 mm Hg. Neurological assessment is as follows: he localizes on the left side but is paretic on the right side. GCS of 10: eye 3, verbal 3, motor 4. Pupils are reactive to light, and other brainstem reflexes were intact. A CT of the head shows no significant changes.

What is the most likely diagnosis in this patient?

The clinical presentation is most consistent with paroxysmal sympathetic hyperactivity (PSH). PSH is defined as a syndrome associated with episodes of increased sympathetic activity. The syndrome can manifest as increased heart rate, increased respiratory rate, increased systolic blood pressure, hyperthermia, diaphoresis, and at times with dystonia. PSH is observed more often in younger than older patients and is more common in men than women. Most reported cases of PSH result from traumatic brain injury (TBI), followed by hypoxic brain injury and stroke. The diagnosis of PSH often can be difficult because of the broad differential diagnosis of abnormal vital signs in the patient after brain injury.1-4

The first step in approaching a patient with this set of disturbances is to investigate the cause of these abnormalities. Although PSH may be the most likely diagnosis, more harmful conditions must be ruled out. The most common etiology for fever and tachycardia in a patient after acute brain injury is infection. Other clinically important considerations include deep vein thrombosis, pulmonary embolism, cardiac events, medication side effects, medication withdrawal symptoms, and neurologic complications. An exhaustive examination for etiologies should be performed. PSH remains a diagnosis of exclusion.

The term “paroxysmal sympathetic hyperactivity” has been adapted and replaces previous terms used to describe the syndrome, such as, episodic autonomic instability, dysautonomia, autonomic dysregulation, central autonomic dysfunction, paroxysmal autonomic instability with dystonia, sympathetic storming, autonomic storming, dysautonomic crises, and diencephalic fits. Recently a consensus statement has attempted to establish standardized diagnostic criteria. The assessment measure is a diagnostic tool that has two components, the first addresses the probability of the diagnosis, which includes clinical features that occur simultaneously, episodes that are paroxysmal in nature, sympathetic overreactivity to normally nonpainful stimuli, features that persist > 3 consecutive days, features that persist > 2 weeks after brain injury, features that persist despite treatment of alternative differential diagnoses, medication ...

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