Extracranial aneurysms of the posterior inferior cerebellar artery

Objective: Extracranial aneurysms of the distal posterior inferior cerebell ar artery (PICA) are extremely rare and sometimes difficult to diagnose wit hout an adequate angiogram, We present the first series of 3 patients who w ere evaluated by the senior author and treated surgically. Methods and Resu lts: All 3 patients presented with subarachnoid hemorrhage (SAH), Clincial symptoms, included occipital headache, nuchal rigidity, abducens nerve pals y and rapid neurologic deterioration. A unilateral injection of the vertebr al artery failed to show the distal contralateral PICA and the aneurysm in 1 patient. All patients underwent aneurysm clipping through a posterior fos sa craniectomy and C-l laminectomy, The aneurysms were located on the tonsi llomedullary segment of the PICA, 10-12 mm below the level of the foramen m agnum, Conclusions: it is important to adequately visualize the distal exte nt of both PICAs or these aneurysms may not be seen. Patients who present w ith SAH must have the entirety of both vertebral arteries evaluated to avoi d 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 patient s developed cerebral vasospasm, Copyright (C) 2000 S. Karger AG, Basel.