Signs: Hypertension, tachycardia, tachypnea, hyperthermia, spasticity, sweating due to surge in circulating catecholamines released from direct trauma to the regulatory centers.

Timing: Usually occurs in the first 2 weeks of injury, medical emergency.

Paroxysmal sympathetic hyperactivity (PSH) is another term for PAI.


There are no universally accepted criteria to date but some features can include:

  • Temp >38.3C
  • HR >120 (or >100 if on beta blockers)
  • SBP >160 mmHg (or >140 mmHg if on beta blockers or other antihypertensives)
  • Respiratory Rate >25 rpm
  • Diaphoresis
  • Posturing/severe dystonia, rigidity or spasticity

Supportive measures include airway protection, sedation, pain control.

Discuss case with TBI attending, but these recommendations act as initial management guidelines

There are no standardized, specific criteria to date, but options include:

Class Drugs and Uses
Lipophilic non-selective β-blocker for hypertension, tachycardia, fever Propranolol 10mg PO, can repeat after 30 min if still tachycardic. max 80 mg/day divided in 3-4 doses
Opioids for tachycardia, vasodilation, allodynic response morphine 1-8mg, frequency according to the onset of PSH
GABA agonists baclofen (5mg TID for pain, clonus, rigidity)
gabapentin (300mg TID for spasticity, allodynic response)
benzodiazepines (for agitation, HTN, tachycardia, posturing)
Centrally acting α2 agonists clonidine 0.1-0.3mg q12h (for HTN)
Dopamine agonists* bromocriptine 1.25-2.5mg q30 min prn with max dose 100 mg/day (for dystonia, fever, posturing)
NSAIDs indomethacin (25-50mg (but avoid with hemorrhagic injury or other bleeding risk)
Other acetaminophen 650-975 mg (but avoid if patient has liver disease or injury)
Ca2+ blocker dantrolene** (for malignant hyperthermia, posturing, rigidity. 0.25-2mg/kg q6-12h)
Non-pharma Cooling blankets, nasogastric tube lavage

*Anterior hypothalamus is temperature sensitive, and the posterior hypothalamus is the heat dissipation center

**dantrolene is not on the formulary at Mount Sinai.

  • References

    Elovic E, Baerga E, Galang GF, Cuccurullo SJ, Reyna M, Malone RJ. Physical Medicine and Rehabilitation Board Review. 3rd ed. New York, NY: Demos Medical; 2015. Chapter 2, Traumatic Brain Injury. P.96-146.

    Baguley IJ, Perkes IE, Fernandez-Ortega JF, Rabinstein AA, Dolce G, Hendricks HT for the Consensus Working Group. Paroxysmal Sympathetic Hyperactivity after Acquired Brain Injury: Consensus on Conceptual Definition, Nomenclature, and Diagnostic Criteria. Journal of Neurotrauma. August 2014, 31(17): P.1515-1520.

    Feng Y, Zheng X, Fang Z. Treatment Progress of Paroxysmal Sympathetic Hyperactivity after Acquired Brain Injury. Pediatr Neurosurg. 2015;50(6):301-9.