title: Pathological examination of a ruptured fusiform aneurysm of the middle cerebral artery.
abstract: BACKGROUND
  Little is known about the pathogenesis and clinical course of fusiform compared with saccular aneurysms. The case of a ruptured fusiform aneurysm accompanied by dissection at the M2 portion of the middle cerebral artery (MCA) is reported, along with pathological findings.
  
  
  METHODS
  A 41-year-old female presenting with subarachnoid hemorrhage was revealed to have a ruptured fusiform aneurysm at the M2 portion of the right MCA on angiography. She was treated with superficial temporal artery-MCA anastomosis and trapping of the aneurysm. The aneurysm consisted of a whitish fusiform dilatation with a thickened wall of the MCA and two red protrusions on it. Pathological examinations revealed disruption and fragmentation of the internal elastic lamina and intimal thickening in the fusiform lesion. There were two aneurysmal protrusions on the main fusiform dilatation. In one protruded lesion, a dissection of the intima was observed.
  
  
  CONCLUSIONS
  We propose that a dissection and saccular aneurysm additionally developed on the wall of a preexisting segmental ectasia of the MCA in our case. In this report, we discuss the etiology of fusiform aneurysms of the MCA.
authors.affiliation: Department of Neurosurgery, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Department of Neurosurgery, Fukui Prefectural Hospital, Fukui, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kida
authors.affiliation: Department of Neurosurgery, Fujita Health University School of Medicine, Nagoya, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Hasegawa
authors.affiliation: Department of Neurosurgery, Asanogawa General Hospital, Kanazawa, Japan.
authors.forename: Junkoh
authors.initials: J
authors.lastname: Yamashita
authors.affiliation: Department of Neurosurgery, Yokohama Sakae Kyosai Hospital, Yokohama, Japan.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Nomura
keywords: Dissecting aneurysm; fusiform aneurysm; internal elastic lamina; intimal thickening; middle cerebral artery