頭部右回転時のみ両側椎骨動脈閉塞性変化を認めたBow Hunter's Strokeの1例

A Case of Bow Hunter's Stroke Caused by Bilateral Vertebral Artery Occlusive Change on Head Rotation to the Right

I．はじめに

　頭位変換により頭蓋外椎骨動脈が閉塞され椎骨脳底動脈循環不全症を来たすことが知られている^{2,4-7,13-15,17-20）}．今回われわれは，頭位変換時の眩暈と失神発作を主訴として来院し，両側椎骨動脈撮影において正中位では異常は認めず，頭部右回転により両側椎骨動脈が同時に高度狭窄を来たし，椎骨脳底動脈循環不全症を呈した1例を経験したので，その発生機序および外科的治療法について文献的考察を加え報告する．

We report a case of bow hunter's stroke caused by simultaneous bilateral vertebral artery occlusivechanges at the right C3-4 and the left C1-2 level on head rotation to the right side. The pathogenesis andsurgical treatment for this particular case are discussed.

A 61-year-old male with cervical spondylosis repeatedly experienced vertebrobasilar insufficiency whenhe rotated his head over 60 degree from the mid-position to the right side. Bilateral vertebral angiographydemonstrated severe compression of the right vertebral artery by a lateral osteophyte and instability at theC3-4 level accompanied with the mechanical stenosis of the left vertebral artery at the C1-2 level only atthe time of turning his head to the right. As the surgical treatment we performed osteophytectomy of theright uncovertebral joint at the C3-4 level in addition to anterior decompression with fusion using hydroxy-apatite spacer and titanium plate at that level. Postoperatively, the patient had no ischemic episodes andthere was angiographical resolution of the rotational stenosis at the C3-4 level.

For the clinical manifestation of bow hunter's stroke on head rotation, it is indispensable that simul-taneous severe occlusive changes present on bilateral vertebral arteries. In case of a vertebral occlusivechange caused by lateral osteophyte at the unstable vertebral joint, anterior decompression and fusion withosteophytectomy may be a wiser approach than arterial decompression or posterior fusion at the C1-2 levelto another vertebral artery occlusive lesion.