椎骨動脈後下小脳動脈分岐部動脈瘤の手術成績  [in Japanese] Saccular Vertebral Aneurysm at the Posterior Inferior Cerebellar Artery: Operative Techniques and Surgical Outcomes  [in Japanese]

椎骨脳底動脈系に発生する動脈瘤の頻度は全頭蓋内動脈瘤のうち5.0-9.6%とされ, その頻度の低さのためか, 治療成績はposterior circulation aneurysmとしてひとまとめに論じられることが多い. しかしながら, 一口にposterior circulationの動脈瘤といっても, 解剖学的な立場からみた手術リスクは, 動脈瘤の部位によって内容も程度も大きく異なる. 個々の部位別の手術リスクは, 破裂, 未破裂を問わず, 動脈瘤の治療において, クリッピング術と血管内手術のどちらを選択するかを決めるうえで, 重要な意味を持つと考えられる. 椎骨動脈-後下小脳動脈分岐部の動脈瘤(以下VA-PICA動脈瘤)は, 全動脈瘤の0.5-3%, posterior circulation動脈瘤の5分の1を占めるとされ, posterior circulationの動脈瘤の中では比較的遭遇する機会の多い動脈瘤であるにもかかわらず, この部位の動脈瘤のみについての手術成績について述べた報告は少ない.

We reviewed the surgical outcomes and operative techniques for 41 saccular vertebral artery aneurysms originating at the posterior inferior cerebellar artery (VA-PICA aneurysms) in 41 patients operated between 1995 and 2003. There were 29 ruptured and 12 unruptured aneurysms. All the aneurysms were clipped satisfactorily with the exception of one case that, showed a small residual neck postoperatively. Using the Glasgow Outcome Scale, surgical outcomes were good recovery in 75.6%; moderate disability, 4.9%; severe disability, 4.9%; persistent vegetative state, 4.9%; and death, 9.8%. Poor clinical outcomes stemmed from the poor preoperative neurological status. Surgery for unruptured aneurysms and delayed surgery for ruptured aneurysms were uncomplicated, while early surgery resulted in transient lower cranial nerve palsy in 3 cases. These transient deficits were tolerable, and patients fully recovered within one month. Technical prerequisites for safe surgery include removing the bone lateral to the foramen magnum as laterally as possible, which enables t,he surgeon to work without retraction of the cerebellum and brainstem. Elective surgery was associated with lower complication rates than early surgery, but the risk of rebleeding was substantial during the waiting period. In view of these results, we recommend surgical clipping for VA-PICA aneurysms whenever possible, and early surgery for ruptured ones.