Abstract
Aneurysms of the posterior circulation pose a unique challenge due to higher rupture rates, higher recurrence rates following endovascular treatment, and extended open cranial base approaches required to reach the ventrally located brainstem circulation. While endovascular therapy has made tremendous strides in successful treatment for most posterior circulation aneurysms, open microscopic approaches remain essential in specific circumstances. Here, we present a case of a patient who presented with acute, severe headache, and sixth nerve palsies, and who was found to have hydrocephalus and a dissecting aneurysm at the anterolateral medullary segment of the posterior inferior cerebellar artery (PICA). Interestingly, this patient had a history of alpha-1 antitrypsin deficiency that has been linked with spontaneous aortic and cervical arterial dissections. The fusiform geometry of the dissecting aneurysm was deemed suboptimal for endovascular treatment, so an open microsurgical approach for occipital artery to PICA bypass and aneurysm trapping was planned. Because this patient had cerebral edema in the setting of a ruptured aneurysm and hydrocephalus, a far lateral craniotomy combined with drilling of the occipital condyle and jugular tubercle was critical to enhance exposure of the first segment of the PICA and to minimize brain retraction. In this video, we highlight the key steps and nuances for harvest of the occipital artery, achieving control of the extracranial vertebral artery, performing the transcondylar and transtubercular far lateral approach, and bypass with trapping technique for these challenging posterior circulation aneurysms. The link to the video can be found at: https://youtu.be/dqgblwX6t0Q .