Intracranial Bypass of Posterior Inferior Cerebellar Artery Aneurysms: Indications, Technical Aspects, and Clinical Outcomes.

Abstract

For some posterior inferior cerebellar artery (PICA) aneurysms, there is no constructive endovascular or direct surgical clipping option. Intracranial bypass is an alternative to a deconstructive technique. To evaluate the clinical features, surgical techniques, and outcome of PICA aneurysms treated with bypass and obliteration of the diseased segment. Retrospective review of PICA aneurysms treated via intracranial bypass was performed. Outcome measurements included postoperative stroke, cranial nerve deficits, gastrostomy/tracheostomy requirement, bypass patency, modified Rankin scale (mRS) at discharge, and mRS at 6 mo. Seven patients with PICA aneurysms treated with intracranial bypass were identified. Five had fusiform aneurysms (4 ruptured, 1 unruptured), 1 had a giant partially thrombosed saccular aneurysm (unruptured), and 1 had a dissecting traumatic aneurysm (ruptured). Two aneurysms were at the anteromedullary segment, 4 at the lateral medullary segment, and 1 at the tonsillomedullary segment. Three patients underwent PICA-to-PICA side to side anastomoses, 2 PICA-to-PICA reanastomosis, 1 vertebral artery-to-PICA bypass, and 1 occipital artery-PICA bypass. Six out of 7 aneurysms were obliterated surgically and 1 with additional endovascular occlusion after the bypass. All bypasses were patent intraoperatively; 2 were later demonstrated occluded without radiological signs or symptoms of stroke. No patients had new cranial nerve deficit postoperatively. With the exception of 1 death due to pulmonary emboli 3 mo postoperatively, all others remain at a mRS ≤ 2. Constructive bypass and aneurysm obliteration remains a viable alternative for treatment of PICA aneurysms not amenable to direct surgical clipping or to a vessel-preserving endovascular option.