Unraveling paroxysmal sympathetic hyperactivity syndrome; what is behind the storm?

Paroxysmal sympathetic hyperactivity syndrome (PSH) is a rarely diagnosed syndrome associated with acute brain injury which involves traumatic brain injury, stroke, infectious diseases, and encephalopathy, and results in cyclic episodes of sympathetic and motor hyperactivity (hypertension, tachypnea, hyperthermia, diaphoresis, dystonic posturing). Even though there are some theories regarding the pathophysiology of PSH, the main mechanism still remains unclear. However, it is mostly agreed upon that PSH is caused by an unbalanced activation of the autonomic nervous system caused by the loss of inhibition of excitation in the sympathetic nervous system. Although PSH has been well known for many decades there were misunderstandings regarding the nomenclature and the definition of this syndrome. The term “Paroxysmal Sympathetic Hyperactivity and a diagnostic tool consisted of two different components and named PSH-Assessment Measure (PSH-AM),” was developed to help guiding clinical management in 2014. These components are the diagnostic likelihood tool and the clinical features scale. To diagnose this syndrome first other neurological issues should be ruled out. Once diagnosed in order to treat and avoid secondary brain damage and other adverse outcomes of this syndrome an approach of both pharmacological (such as opioids, B-blockers, alfa2 agonists, benzodiazepines, gabapentin and muscle relaxants) and nonpharmacological should be combined. Pharmacological approach focuses on symptom abortion, prevention and refractory treatment.