短期間で頭頚部主幹動脈に多様な血管解離を来した線維筋性形成異常症の1例

A Case of Fibromuscular Dysplasia in a Patient with Various Main Trunk Dissections in the Head and Neck over a Short Period

Ⅰ．はじめに

　本邦において頭痛のみで発症した頭蓋内解離性動脈瘤は，山浦らの報告によると，全体の7%であり²⁰⁾，自然改善例も多く，一般に予後は良好とされている^7）．

　一方，頚部内頚動脈解離も若年者脳卒中の原因の1つであるが^1），本邦では発生頻度が低く，多発解離であったとする症例の多くが線維筋性形成異常症（fibromuscular dysplasia：FMD）と診断されている^9,14,18)．厚生労働省特定疾患研究班による診断の手引きによれば，FMDの診断には脳血管撮影ないし病理学的検討のいずれかが必要であり，脳血管撮影での念珠状変化は典型的所見とされる．診断はこの所見が得られれば確定となる．

　今回われわれは，頭痛発症の椎骨動脈解離が短期間でくも膜下出血を来し，さらには経過中に両側頭蓋外内頚動脈と健側椎骨動脈の3血管に念珠状変化が明らかとなり，上記の診断基準からFMDの診断に至った症例を経験した．画像所見やFMDと解離の関連を中心に報告する．

　We report a case of subarachnoid hemorrhage（SAH）from an intracranial vertebral artery（VA）dissection in a patient with fibromuscular dysplasia（FMD）who presented with headache. A 54-year-old woman complained of spontaneous occipital headache. The dilatation of the left VA was detected on magnetic resonance angiography（MRA). She was diagnosed with left VA dissection（headache onset type). After sudden onset of headache on the second day of hospitalization, her consciousness level, as defined by the Japan Coma Scale, was 300. Computed tomography（CT）revealed SAH. Cerebral angiography showed the dilatation of the left intracranial VA and contrast material pooling, which was suspected to be a sign of dissection. We performed VA intravascular ligation by coil embolization. The postoperative course was good but postoperative MRA revealed arterial wall irregularities in both the extra cranial internal carotid artery and the right VA. Cerebral angiography showed the presence of the string-of-beads sign at these arteries. She was diagnosed with FMD.

　SAH might develop during the follow-up period in patients with VA dissection, even those in whom the initial symptom is headache. In addition, cases of FMD might also be complicated by various lesions of the main trunk of the cerebral artery.