Paroxysmal Sympathetic Hyperactivity After Acquired Brain Injury: An Integrative Review of Diagnostic and Management Challenges

Paroxysmal sympathetic hyperactivity (PSH) mainly occurs after acquired brain injury (ABI) and often presents with high fever, hypertension, tachycardia, tachypnea, sweating, and dystonia (increased muscle tone or spasticity). The pathophysiological mechanisms of PSH are not fully understood. Currently, there are several views: (1) disconnection theory, (2) excitatory/inhibitory ratio, (3) neuroendocrine function, and (4) neutrophil extracellular traps. Early diagnosis of PSH remains difficult, given the low specificity of its diagnostic tools and unclear pathogenesis. According to updated case analyses in recent years, PSH is now more commonly observed in patients with stroke, with tachycardia and hypertension as the main clinical manifestations, which is not fully consistent with previous data. To date, the PSH Assessment Measure tool is optimal for the early identification of PSH and stratification of symptom severity. Clinical strategies for the management of PSH are divided into three main points: (1) reduction of stimulation, (2) reduction of sympathetic excitatory afferents, and (3) inhibition of the effects of sympathetic hyperactivity on target organs. However, use of drugs and standards have not yet been harmonized. Further investigation on the relationship between PSH severity and long-term neurological prognosis in patients with ABI is required. This review aimed to determine the diagnostic and management challenges encountered in PSH after ABI.