title: Extracranial aneurysms of the posterior inferior cerebellar artery.
abstract: OBJECTIVE
  Extracranial aneurysms of the distal posterior inferior cerebellar artery (PICA) are extremely rare and sometimes difficult to diagnose without an adequate angiogram. We present the first series of 3 patients who were evaluated by the senior author and treated surgically.
  
  
  RESULTS
  All 3 patients presented with subarachnoid hemorrhage (SAH). Clincial symptoms, included occipital headache, nuchal rigidity, abducens nerve palsy and rapid neurologic deterioration. A unilateral injection of the vertebral artery failed to show the distal contralateral PICA and the aneurysm in 1 patient. All patients underwent aneurysm clipping through a posterior fossa craniectomy and C-1 laminectomy. The aneurysms were located on the tonsillomedullary segment of the PICA, 10-12 mm below the level of the foramen magnum.
  
  
  CONCLUSIONS
  It is important to adequately visualize the distal extent of both PICAs or these aneurysms may not be seen. Patients who present with SAH must have the entirety of both vertebral arteries evaluated to avoid missing these aneurysms. The aneurysms were located adjacent to the atlas necessitating an upper cervical laminectomy for adequate surgical exposure. In general, the patients did well postoperatively and none of the patients developed cerebral vasospasm.
authors.affiliation: Department of Neurosurgery, Hospital of the University of Pennsylvania, Philadelphia, Pa., USA. jabraham@mail.med.upenn.edu
authors.forename: J M
authors.initials: JM
authors.lastname: Abrahams
authors.forename: J E
authors.initials: JE
authors.lastname: Arle
authors.forename: R W
authors.initials: RW
authors.lastname: Hurst
authors.forename: E S
authors.initials: ES
authors.lastname: Flamm
mesh_terms: D000293:Adolescent; D000328:Adult; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D014711:Vertebral Artery