title: Paraparesis associated with ruptured anterior cerebral artery territory aneurysms.
abstract: BACKGROUND
  Paraparesis is a rare but characteristic manifestation of ruptured anterior communicating artery or anterior cerebral artery (ACA) aneurysms, but the pathogenesis remains unclear. This study investigated the neuroimaging and clinical features of patients with such paraparesis to evaluate possible causes.
  
  
  METHODS
  Nine of 178 patients with ruptured anterior communicating artery or ACA aneurysms presented with paraparesis among 462 patients with subarachnoid hemorrhage (SAH) admitted between May 1996 and November 2001. Diffusion-weighted magnetic resonance (MR) imaging was performed within 48 hours of the onset of SAH in 4 of these 9 patients. The clinical course and neuroimaging studies of these 4 patients were retrospectively reviewed.
  
  
  RESULTS
  Diffusion-weighted MR imaging revealed -intensity areas in the medial aspects of the bilateral frontal lobes, which were supplied by the ACAs and distal to the aneurysms, in all 4 patients. These high-intensity lesions had normal to subnormal values of apparent diffusion coefficient (ADC). Most of the high-intensity lesions recovered and did not result in the final lesions regardless of the ADC values, but some lesions with subnormal ADC values resulted in cerebral infarction. Paraparesis was transient and almost completely resolved in 3 patients.
  
  
  CONCLUSIONS
  Diffusion-weighted MR imaging detected primary brain damage in the ACA territories caused by acute SAH, which was compatible with the clinical paraparesis. Primary brain damage caused by SAH may include 3 types of lesions: reversible with normal ADC value, reversible with subnormal ADC value, and irreversible with subnormal ADC value.
authors.affiliation: Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Endo
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shimizu
authors.forename: Teiji
authors.initials: T
authors.lastname: Tominaga
mesh_terms: D000368:Aged; D017542:Aneurysm, Ruptured / Q000150:complications* / Q000473:pathology*; D001921:Brain / Q000098:blood supply / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000473:pathology*; D008875:Middle Aged; D020335:Paraparesis / Q000209:etiology*; D013345:Subarachnoid Hemorrhage / Q000209:etiology