title: Ruptured aneurysm associated with arachnoid cyst: intracystic hematoma without subarachnoid hemorrhage.
abstract: BACKGROUND
  It is well-known that arachnoid cysts of the middle fossa are associated often with chronic subdural hematomas and/or intracystic hemorrhages. However, reports of an arachnoid cyst associated with an aneurysm are rare.
  
  
  METHODS
  A 45-year-old man was admitted with headache due to intracystic hemorrhage in the sylvian fissure, associated with a saccular aneurysm at the bifurcation of the internal carotid artery. The aneurysm ruptured into the arachnoid cyst, without causing a subarachnoid hemorrhage. Subsequently, the neck of the aneurysm was clipped successfully. The patient's postoperative course was uneventful, and there was no vasospasm.
  
  
  CONCLUSIONS
  This is the first reported case of an intracystic hematoma due to a ruptured aneurysm. We discuss the possible etiology of the association between the aneurysm and the arachnoid cyst, and the formation mechanism for the intracystic hematoma that did not result in a subarachnoid hemorrhage.
authors.affiliation: Department of Neurosurgery, Harue Hospital, Fukui, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Hirose
authors.forename: S
authors.initials: S
authors.lastname: Shimada
authors.forename: N
authors.initials: N
authors.lastname: Yamaguchi
authors.forename: K
authors.initials: K
authors.lastname: Hosotani
authors.forename: H
authors.initials: H
authors.lastname: Kawano
authors.forename: T
authors.initials: T
authors.lastname: Kubota
mesh_terms: D016080:Arachnoid Cysts / Q000150:complications*; D006406:Hematoma / Q000209:etiology*; D006801:Humans; D002532:Intracranial Aneurysm / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012422:Rupture, Spontaneous; D013345:Subarachnoid Hemorrhage / Q000209:etiology