Original ArticleIntracranial Vertebral Artery Aneurysms: Clinical Features and Outcome of 190 Patients
Introduction
Aneurysms of the vertebral artery (VA) comprise approximately one-third of all posterior circulation aneurysms (49). Their characteristic morphologic and anatomic features make them unique among other intracranial aneurysms. Morphologically, a VA aneurysm can range from a small, saccular aneurysm in the VA–posterior inferior cerebellar artery (PICA) junction to a fragile, dissecting fusiform lesion, or to a giant aneurysm with brainstem compression. Anatomically, they are located deep in the posterior fossa in close proximity to the brainstem and cranial nerves.
With the exception of a 1996 report by Drake, Peerless, and Hernesniemi (12) of a series with 195 VA aneurysm patients, series on VA aneurysms are relatively small, mostly with <50 patients 1, 2, 3, 4, 5, 6, 10, 11, 12, 14, 27, 32, 36, 41, 42, 49. After International Subarachnoid Aneurysm Trial (ISAT), most recent VA aneurysm studies focus on endovascular treatment 2, 5, 6, 10, 14, 27, 32, 36, 38.
In this retrospective study, we present 190 consecutive patients with 193 VA aneurysms treated mainly by microneurosurgical clipping. This series includes aneurysms originating from the VA itself or the VA–PICA junction. No distal PICA aneurysms reported earlier are included in the present report (28). Our aim is to describe the typical anatomic and morphologic features of VA aneurysms, to analyze the treatment outcome, and in particular to compare those that ruptured with aneurysms that ruptured at other locations.
Section snippets
Classification of VA Aneurysms
The 2 vertebral arteries are usually the first and largest branches originating from the subclavian arteries. Occasionally, they can arise from other sites, mainly from the aortic arch. VAs are divided into 4 segments, namely V1–V4, with V4 being the intradural segment (25). Distally VAs end by joining to form the basilar artery. To classify the VA aneurysms more exactly, we used the classification of Drake, Peerless, and Hernesniemi (12) subdiving the aneurysms into 4 groups according to their
Patients
The 190 patients had a total of 193 VA aneurysms. After 2000, the start of regular use of CTA and MRA in our department, the prevalence of VA aneurysms has been 2.0% of all and 3.5% of the ruptured aneurysms. Among all patients with intracranial aneurysms, a VA aneurysm was diagnosed in 2.8% of patients. Before the 1980s we found 16 patients; from 1980 to 1989 we found 31 patients; from 1990 to 1999 we found 35 patients; with the remaining 108 patients diagnosed after 2000. The first VA
Discussion
We studied 190 patients with 193 VA aneurysms. Among all patients with aneurysms, 2.8% had a VA aneurysm. Patients with ruptured VA aneurysms were older than those with ruptured aneurysms at other locations. More VA aneurysms were fusiform, and when ruptured, more often caused intraventricular hemorrhage than did other aneurysms. Among fusiform (dissecting) aneurysms, the only method definitively preventing rebleeding was trapping. Despite often the higher Fisher and H&H grades, the aneurysm's
Conclusions
Of our patients with intracranial aneurysms, 2.8% had a VA aneurysm. In patients with a ruptured VA aneurysm, the risk factors for death at 1 year in univariate analysis were old age, male sex, and high H&H grade. The anatomic and morphologic features of these aneurysms make their treatment challenging. Despite many cases of severe bleeding and the risk of laryngeal palsy caused by surgery, among patients surviving 1 year after diagnosis, the outcome may be favorable, with almost all returning
Acknowledgments
We thank Carolyn Brimley Norris for language advice.
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Conflict of interest statement: This study was funded by the Maire Taponen Foundation and the Emil Aaltonen Foundation.