title: Venous drainage in perimesencephalic hemorrhage.
abstract: OBJECTIVE
  In perimesencephalic nonaneurysmal hemorrhage (PMH), subarachnoid blood accumulates around the midbrain. Clinical and radiological characteristics suggest a venous origin of PMH. We compared the venous drainage of the midbrain between patients with PMH and aneurysmal subarachnoid hemorrhage (aSAH) by means of computed tomography angiography (CTA).
  
  
  METHODS
  CTAs of 55 PMH patients and 42 aSAH patients with a posterior circulation aneurysm were reviewed. Venous drainage was classified into: (1) normal continuous: the basal vein of Rosenthal is continuous with the deep middle cerebral vein and drains mainly to the vein of Galen (VG); (2) normal discontinuous: drainage anterior to uncal veins and posterior to VG; and (3) primitive variant: drainage to other veins than VG. Additionally, we compared in PMH patients the side of the primitive variant and side of the bleeding.
  
  
  RESULTS
  A primitive variant was present on one or both hemispheres in 53% of PMH patients with PMH (95% CI, 40% to 65%) and in 19% of aSAH patients (95% CI, 10% to 33%). In all 16 PMH patients with a unilateral primitive drainage, blood was seen on the side of the primitive drainage (100%; 95% CI, 81% to 100%); blood was never found mainly on the side with normal drainage.
  
  
  CONCLUSIONS
  Patients with PMH have a primitive venous drainage directly into dural sinuses instead of via the vein of Galen more often than do controls. Moreover, the side of the perimesencephalic hemorrhage relates to the side of the primitive drainage. These results further support a venous origin of PMH.
authors.affiliation: Department of Radiology, University Medical Centre Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands. irenemarieke@yahoo.com
authors.forename: Irene C
authors.initials: IC
authors.lastname: van der Schaaf
authors.forename: Birgitta K
authors.initials: BK
authors.lastname: Velthuis
authors.forename: Alida
authors.initials: A
authors.lastname: Gouw
authors.forename: Gabriel J E
authors.initials: GJ
authors.lastname: Rinkel
mesh_terms: D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation; D006801:Humans; D020300:Intracranial Hemorrhages / Q000000981:diagnostic imaging*; D008636:Mesencephalon / Q000098:blood supply* / Q000000981:diagnostic imaging; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging*