title: Underlying venous pathology causing perimesencephalic subarachnoid hemorrhage.
abstract: BACKGROUND
  Perimesencephalic subarachnoid hemorrhage (PSH) is a relatively benign clinical entity with a low risk of recurrent bleeding. The precise etiology of PSH has not yet been determined. We report here three cases of PSH with clinical and radiological features that support a venous system as a cause.
  
  
  METHODS
  The first patient, a 72-year-old woman, had PSH and venous hemorrhagic infarct in the left thalamus on non-contrast CT. Subsequent cerebral angiography revealed widespread thrombosis in the cerebral venous system, a potential cause for reflux overflow hemorrhage. The second patient, a 55-year-old man with an established diagnosis of neuro-Behçet's disease, a well-known cause for cerebral venulitis, presented with PSH one year later. The third patient, a 39-year-old female, with incomplete Behçet's disease was admitted with PSH.
  
  
  CONCLUSIONS
  Current concepts on the anatomic origin and the possible pathophysiologic mechanism leading to PSH are discussed. The underlying pathological conditions in the venous system in our cases provide theoretical clues to the anatomic origin of PSH in general.
authors.affiliation: Department of Medicine, Samsung Medical Centre, Seoul, Republic of Korea.
authors.forename: Jaejoon
authors.initials: J
authors.lastname: Lee
authors.forename: Eun-Mi
authors.initials: EM
authors.lastname: Koh
authors.forename: Chin-Sang
authors.initials: CS
authors.lastname: Chung
authors.forename: Seung-Chul
authors.initials: SC
authors.lastname: Hong
authors.forename: Yong-Bum
authors.initials: YB
authors.lastname: Kim
authors.forename: Pil-Wook
authors.initials: PW
authors.lastname: Chung
authors.forename: Bum-Chun
authors.initials: BC
authors.lastname: Suh
authors.forename: Heui-Soo
authors.initials: HS
authors.lastname: Moon
mesh_terms: D000328:Adult; D000368:Aged; D002533:Cerebral Angiography / Q000379:methods; D002550:Cerebral Veins / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008636:Mesencephalon / Q000473:pathology*; D008875:Middle Aged; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging* / Q000209:etiology*; D014057:Tomography, X-Ray Computed / Q000379:methods; D014652:Vascular Diseases / Q000150:complications* / Q000000981:diagnostic imaging*