Aneurysms of the vertebral and posterior inferior cerebellar arteries

Objective: Aneurysms of the vertebral artery (VA) and its branch posterior inferior cerebellar artery (PICA) are rare, comprising only about 1 to 3% of all intracranial aneurysms. The series published thus far on these lesions are small. We aim to describe the special anatomical and morphological features of these aneurysms compared to aneurysms in other locations, and to describe the variety of symptoms they cause. We describe their treatment and analyze the outcome. Additionally, we describe their anatomy imaged with computed tomography angiography. Patients and methods: We reviewed retrospectively 9 709 consecutive patients with intracranial aneurysms treated in the Department of Neurosurgery at Helsinki University Central Hospital, Finland, between 1934 and 2011. The study population included 268 patients with 284 VA or PICA aneurysms or both. Follow-up data came from the Population Registry Centre (dates of death), Statistics Finland (causes of death), from written questionnaires to patients still alive, medical records of the Department of Neurosurgery, and for those deceased, medical records from all public health services. Results: Among all the aneurysm patients, 5.1% had an aneurysm in the VA or PICA. Most aneurysms, 51%, were located at the VA PICA junction. The proportion of fusiform aneurysms was 28%. Compared to patients with ruptured aneurysms at other locations, patients with a ruptured VA or PICA aneurysm were older and had a higher Fisher grade. Ruptured distal PICA aneurysms also re-bled more regularly. Compared to other ruptured aneurysms, ruptured VA and PICA aneurysms were smaller and more often fusiform. At least one VA or PICA aneurysm was treated in 209 (78%) patients. The most common technique for aneurysm occlusion was clipping, used in 107 aneurysms. Total occlusion of the aneurysm was achieved among saccular aneurysms in 90%, and among fusiform aneurysms in 61%. Within one year of aneurysm diagnosis, 26% of the patients were dead. Among those who survived a minimum one year and in whom the VA or PICA aneurysm received active treatment; those returning to an independent or their previous stage of life amounted to 92%. Conclusion: In treatment of VA and PICA aneurysms, their special anatomical and morphological features are challenge. Despite this, and often severe hemorrhage, most patients surviving the initial stage make a good recovery.