title: Quadrigeminal variant of perimesencephalic nonaneurysmal subarachnoid hemorrhage.
abstract: OBJECTIVE
  Perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSH) is a benign entity with a low risk of rebleeding. The most widely accepted definition emphasizes the presence of blood ventral to the midbrain or pons on early computed tomography. We sought to determine the frequency of PNSH with blood centered in the quadrigeminal cistern.
  
  
  METHODS
  We reviewed a prospectively collected database of all patients admitted to our institution over a 2.5-year period with subarachnoid hemorrhage (SAH) and identified PNSH patients from early computed tomographic scans and negative four-vessel angiograms.
  
  
  RESULTS
  Of 220 SAH patients, we identified 9 with PNSH. Two (22%) of these patients had SAH centered in the quadrigeminal cistern without pretruncal blood, negative repeat angiograms, and an uncomplicated clinical course.
  
  
  CONCLUSIONS
  Quadrigeminal SAH is a variant of PNSH that is not well described in the literature. It may comprise up to one-fifth of PNSH cases and carries a similar benign prognosis.
authors.affiliation: Department of Neurological Surgery, Neurological Institute of New York, New York Presbyterian Hospital, USA.
authors.forename: T H
authors.initials: TH
authors.lastname: Schwartz
authors.forename: S A
authors.initials: SA
authors.lastname: Mayer
mesh_terms: D000368:Aged; D002533:Cerebral Angiography; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003336:Tectum Mesencephali / Q000098:blood supply* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed