Prognostic influence and magnetic resonance imaging findings in paroxysmal sympathetic hyperactivity after severe traumatic brain injury.

Paroxysmal sympathetic hyperactivity (PSH) is a clinical syndrome affecting a subgroup of survivors of severe brain injury. In this study, the prevalence, magnetic resonance imaging (MRI) presentation, influence on the clinical course in the intensive care unit (ICU), and effect on neurological recovery of PSH were prospectively surveyed in 87 patients with severe traumatic brain injury (TBI). Cranial MRI was performed during the first 30 days after injury. The outcome was assessed according to the Glasgow Outcome Scale (GOS). PSH occurred in 18.4% of patients, with a greater incidence among younger patients and those with lower Glasgow Coma Scale (GCS) scores. Patients with PSH had more deep lesions as shown on cranial MRI, significantly longer ICU stays, and worse outcomes. PSH was shown to be common among patients with severe TBI who also had deep intraparenchymal lesions. The mechanism by which PSH influences patient outcomes has yet to be defined, but we believe that it may be mediated by diencephalic-mesencephalic dysfunction or disconnection.