Treatment of dissecting aneurysms of the PICA: anatomical considerations and clinical outcome

Posterior inferior cerebellar artery (PICA) dissecting aneurysms require rapid and aggressive treatment by sacrificing the parent vessel of the aneurysm-bearing dissected vessel. We assessed the clinical consequences of PICA occlusion in view of the local vascular anatomy. We performed a retrospective search of our neurovascular database in the period 2007-2012. Patient characteristics, including clinical presentation, WFNS (World Federation of Neurosurgical Societies) grading and Glasgow Outcome Scale (GOS), were recorded. CT and CT angiographic findings as well as the detailed vascular anatomy including collateral circulation were assessed. We identified 10 patients (5 male; mean age 50 years). Eight patients presented with WFNS grade I and II, one with grade IV and one with grade V. All patients were treated with parent vessel occlusion (PVO). An extradural PICA origin was seen in three patients. Collateral circulation was visible before PVO in two and after PVO in seven additional patients. Despite the presence of collaterals, mild cerebellar ischemia occurred in three patients, without development of a Wallenberg syndrome. Outcome was favorable in 9 patients (8 patients GOS 5, one patient GOS 4). One patient died due to the mass effect of the initial cerebellar hematoma. PVO to treat PICA dissecting aneurysms was well tolerated with a 90% favorable outcome. Regional collateral circulation and vascular variations permitted relative safe vessel occlusion with only minor cerebellar symptoms in this small group of patients