title: Frameless stereotaxy-assisted clipping of distal anterior cerebral artery aneurysm: technical note and case series.
abstract: OBJECTIVE
  Microsurgery for the clipping of cerebral aneurysms requires a working knowledge of the anatomy of the cerebral vasculature and its relationship to landmarks on the surface of the brain and along the skull base. However, for more distally located aneurysms of the anterior cerebral artery (ACA), locating the lesion can prove frustrating and may require much more extensive interhemispheric dissection than is otherwise needed for proximal control, exposure of the aneurysm, and clip application. We report a case series of five patients in which frameless stereotaxy and CT angiographic data sets were used to minimize the extent of surgery required to clip distal ACA aneurysms.
  
  
  METHODS
  Five patients were found to have distal ACA aneurysms during the work-up of subarachnoid hemorrhage or other neurologic symptoms. The patients comprised two with subarachnoid hemorrhage, one with dizziness, one with stroke, and one with migraines and polycystic kidney disease. Each patient was found to have an aneurysm at the pericallosal/callosal marginal junction.
  
  
  METHODS
  All five patients underwent a right parasagittal craniotomy and clipping of a distal ACA aneurysm. The location of the craniotomy and subsequent interhemispheric dissection were guided by CT angiographic data sets and computer-assisted frameless stereotaxy.
  
  
  CONCLUSIONS
  Frameless stereotaxy using a CT angiographic data set is a useful adjunct to routine microsurgery in the clipping of distal ACA aneurysms. Its use obviates the need for extensive interhemispheric dissection, allows the surgeon to gain proximal control and expose the aneurysm more efficiently, and should minimize complications related to unwitting aneurysm exposure.
authors.affiliation: Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA. weshsu@jhmi.edu
authors.forename: Wesley
authors.initials: W
authors.lastname: Hsu
authors.forename: Neal J
authors.initials: NJ
authors.lastname: Naff
authors.forename: Richard E
authors.initials: RE
authors.lastname: Clatterbuck
mesh_terms: D000368:Aged; D000784:Aortic Dissection / Q000473:pathology / Q000601:surgery*; D000792:Angiography; D002543:Cerebral Hemorrhage / Q000601:surgery; D003399:Craniotomy / Q000295:instrumentation; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000473:pathology / Q000601:surgery*; D008866:Microsurgery / Q000295:instrumentation; D008875:Middle Aged; D013238:Stereotaxic Techniques / Q000295:instrumentation*; D020521:Stroke; D013345:Subarachnoid Hemorrhage / Q000601:surgery