Abstract: Objective To investigate the microsurgical treatment of aneurysms of the posterior inferior cerebellar artery(PICA).Methods The clinical data,including manifestations,treatment,operative findings,and prognoses of 19 patients with aneurysm of the PICA who underwent microsurgery 1997.5～2005.5 in Beijing Tiantan Hospital were reviewed retrospectively.Results All the 19 patients received microscopic neurosurgery,5 cases were male,and 14 cases were female,aged from 20 to 59 years,average 36.1±15.7 years.Aneurysms in eleven cases located at the left side,and 8 cases at the right side.There were 15 cases presenting firstly with hemorrhage(manifesting with sudden headache,vomiting,or conscious disturbance),5 cases with SAH(subarachnoid hemorrhage),3 cases with ICbH(intracerebellar hemorrhage),3 cases with IVH(intraventricular hemorrhage),4 cases with SAH and IVH.Four cases had spaceoccupying masses as the initial sign presenting with headache,dizziness,or walking unsteadiness.Diagnoses of all of the 19 cases were confirmed by DSA examination,which revealed saccular aneurysm in 17 cases,fusiform aneurysm in 2 cases.The diameters of aneurysms were from 5 to 20 millimeters.Five cases had their aneurysms located at the first section,1 at the third section,2 at the fourth section,11 at the fifth section.There were 5 cases complicated with other angiodysplasia,3 cases with other aneurysms:1 case with arteriovenous malformation(AVM) at the vermis cerebellum of the same side;1 case with the arteriovenous fistula(AVF) of anterior inferior cerebellar artery at the same side.Posterior-median approaches was performed in 15 cases,and far-lateral approaches in 4 cases.Aneurysmal clipping were performed in 8 cases,aneurysmal clipping and resection in 9 cases,aneurysmal clipping and AVM resection in 1 case,aneurysmal resection after clipping and AVF resection in 1 case.Two patients had minor complications after operation,1 case with slight hydrocephalus,1 case with horizontal nystagmus,other cases were all uneventful.Conclusion The incidence of PICA aneurysm is low,and always presenting with hemorrhage or mass effect in contrast to those elsewhere.If the aneurysm being located at the 1～3 section,the far-lateral craniotomy is performed;and if located in the 4～5 section,posterior-median approach is prefered.The option of operation depends on the shape and the stalk width of the aneurysm,fusiform or wide-neck aneurysm received aneurysmal clipping and resection,while,saccular or tight-neck aneurysm received aneurysmal clipping,if complicated with other angiodysplasia,it is better to managed at the same time.The outcome of microsurgical treatment of PICA aneurysm is good.

Key words: posterior inferior cerebellar artery, intracranial aneurysms, microsurgery