title: Paroxysmal sympathetic hyperactivity in hemispheric intraparenchymal hemorrhage.
abstract: BACKGROUND
  Paroxysmal sympathetic hyperactivity (PSH) is a hyperadrenergic syndrome that may follow acute brain injury characterized by episodic, hyperadrenergic alterations in vital signs. Identifying commonality in lesion localization in patients with PSH is challenging, but intraparenchymal hemorrhage (IPH) represents a focal injury that might provide insight. We describe a series of patients with IPH that developed PSH, and review the literature.
  
  
  METHODS
  Patients with IPH who developed PSH were identified from OHSU hospital records. A literature review was conducted to identify similar cases through PUBMED, OVID, and Google Scholar.
  
  
  RESULTS
  Three cases meeting criteria for PSH were identified. Hemorrhage volume ranged from 70 to 128 mL, and intracranial hemorrhage score ranged from 2 to 3. The laterality of the hemorrhage and significant volume of hemorrhage was similar in each of the patients, specifically all hemorrhages were large, subcortical, and right-sided. A literature search identified six additional cases, half of whom reported a right hemisphere hemorrhage and the majority also had subcortical localization.
  
  
  CONCLUSIONS
  Our literature review identified six cases of IPH associated with PSH with five cases having subcortical lesion locations, echoing the areas of disruption in our three cases. On the basis of these observations, we hypothesize that injuries along the pathway from the insular cortex to downstream sympathetic centers may remove tonic inhibition leading to unchecked sympathetic outflow. Prospective investigations of lesion location in patients with IPH and PSH are warranted to test this hypothesis, especially with advanced neuroimaging techniques.
authors.affiliation: Department of Neurology, Oregon Health & Science University, Portland, Oregon.
authors.forename: Billy
authors.initials: B
authors.lastname: Gao
authors.affiliation: Department of Radiology, Oregon Health & Science University, Portland, Oregon.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Pollock
authors.affiliation: Department of Neurology, Oregon Health & Science University, Portland, Oregon.
authors.forename: Holly E
authors.initials: HE
authors.lastname: Hinson