title: Familial perimesencephalic subarachnoid hemorrhage: two case reports.
abstract: BACKGROUND
  Non-aneurysmal spontaneous subarachnoid hemorrhage is characterized by an accumulation of a limited amount of subarachnoid hemorrhage, predominantly around the midbrain, and a lack of blood in the brain parenchyma or ventricular system. It represents 5% of all spontaneous subarachnoid hemorrhage cases. In spite of extensive investigation, understanding of the mechanisms leading to perimesencephalic non-aneurysmal subarachnoid hemorrhage remains incompletely defined. A growing body of evidence has supported a familial predisposition for non-aneurysmal spontaneous subarachnoid hemorrhage.
  
  
  METHODS
  A 39-year-old Caucasian man presented with sudden onset headache associated with diplopia. His computed tomography scan revealed perimesencephalic subarachnoid hemorrhage. A cerebral angiogram showed no apparent source of bleeding. He was treated conservatively and discharged after 1 week without any neurological deficits. The older brother of the first case, a 44-year-old Caucasian man, presented 1.5 years later with acute onset of headache and his computed tomography scan also showed perimesencephalic non-aneurysmal subarachnoid hemorrhage. He was discharged home with normal neurological examination 1 week later. Follow-up angiograms did not reveal any source of bleeding in either patient.
  
  
  CONCLUSIONS
  We report the cases of two siblings with perimesencephalic non-aneurysmal subarachnoid hemorrhage, which may further suggest a familial predisposition of non-aneurysmal spontaneous subarachnoid hemorrhage and may also point out the possible higher risk of perimesencephalic non-aneurysmal subarachnoid hemorrhage in the first-degree relatives of patients with perimesencephalic non-aneurysmal subarachnoid hemorrhage.
authors.forename: Ulaş
authors.initials: U
authors.lastname: Cıkla
authors.forename: Beverly
authors.initials: B
authors.lastname: Aagaard-Kienitz
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Turski
authors.forename: Guner
authors.initials: G
authors.lastname: Menekse
authors.forename: David B
authors.initials: DB
authors.lastname: Niemann
authors.affiliation: Department of Neurological Surgery, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA. m.baskaya@neurosurgery.wisc.edu.
authors.forename: Mustafa K
authors.initials: MK
authors.lastname: Başkaya
mesh_terms: D000328:Adult; D002533:Cerebral Angiography; D002550:Cerebral Veins / Q000002:abnormalities*; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008636:Mesencephalon / Q000098:blood supply* / Q000473:pathology; D035781:Siblings; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis* / Q000235:genetics; D014057:Tomography, X-Ray Computed