Introduction: For some Posterior Inferior Cerebellar Artery (PICA) aneurysms, there is no constructive endovascular or direct surgical clipping option. Intracranial bypass in such cases is an alternative to deconstructive technique. We evaluate the clinical features, surgical technique, and outcomes of PICA aneurysms treated by bypass and obliteration of the diseased segment.
Methods: Retrospective review of all PICA aneurysms treated over the past five years was performed. Clinical outcome measurements included post-operative stroke, cranial nerve deficits, gastrostomy/tracheostomy requirement, bypass patency, modified Rankin scale (mRS) at discharge, and mRS at 6 months.
Results: Six patients with PICA aneurysms treated with intracranial bypass were identified. Four had fusiform aneurysms (three ruptured, one unruptured), one had a giant partially thrombosed saccular aneurysm (unruptured), and one had a dissecting traumatic aneurysm (ruptured). Two aneurysms were at the anteromedullary segment, three at the lateral medullary segment, and one at the tonsilomedullary segment. Three bypasses were PICA to PICA side-side, one was PICA to PICA reanastomosis, one was vertebral artery-PICA, and one was occipital artery-PICA bypass. Five out of 6 aneurysms were obliterated surgically, and one underwent endovascular occlusion after the bypass. All bypasses were patent intraoperatively, although two were later demonstrated to be occluded with no radiological signs or symptoms of stroke. None of the patients had new cranial nerve deficits post-operatively. With the exception of one death due to pulmonary emboli three months postoperatively, all other patients remain at a mRS <2.
Conclusions: Intracranial bypass for PICA aneurysms remains an effective means of PICA preservation and aneurysm occlusion. Considering the risk of major stroke and neurological morbidity associated with sacrifice of the first three segments of PICA, a constructive alternative by bypass and aneurysm obliteration should remain a viable alternative for treatment of PICA aneurysms not amenable to direct surgical clipping or to vessel preserving endovascular treatment.
Patient Care: We hope to increase understanding and appreciation for bypass techniques for PICA aneurysm treatment such that difficult to treat aneurysms can be more safely obliterated.
Learning Objectives: By the conclusion of the segment, participants should be able to: 1) identify appropriate circumstances for intracranial PICA bypass for aneurysm occlusion and 2) understand bypass graft options for PICA bypass