合併する椎骨動脈瘤破裂によるくも膜下出血で発症したと考えられるcerebrovascular fibromuscular dysplasiaの1例

Subarachnoid Hemorrhage due to a Ruptured Intracranial Vertebral Artery Aneurysm Associated with Cerebrovascular Fibromuscular Dysplasia: Case Report

Ⅰ．はじめに

　線維筋異形成症（fibromuscular dysplasia：FMD）は腎動脈や頚動脈などの中小動脈の，特に中膜に変化を伴う，非動脈硬化性，非炎症性の血管病変である²²⁾．頭頚部FMDの患者の平均発症年齢は約50歳で^16,21)，欧米の報告例に比べわが国における発症例は少ない^6,14)．頭頚部FMDはほとんどが頚部内頚動脈に生じ，頭蓋内の血管へ病変が出現する例は稀である^11,12,23)．今回われわれは合併する頭蓋内椎骨動脈の動脈瘤破裂によるくも膜下出血で発症し，血管撮影では多彩な血管像を呈したFMDの1例を経験したので報告する．

　Fibromuscular dysplasia (FMD) is comprised of a group of nonatherosclerotic and noninflammatory arterial diseases. Cerebrovascular FMD occurs more frequently in women,and the mean age at which it is diagnosed is 50 years. The most common angiographic pattern of cerebrovascular FMD is the “string-of-beads” deformity at the extracranial internal carotid artery. We report the case of a 52-year-old woman who presented with a sudden severe headache and went into a deep coma. She had been complaining of headaches for 2 weeks,but no specific imaging findings were obtained. A computed tomography scan obtained on admission showed a diffuse subarachnoid hemorrhage (SAH) from the cerebellomedullary cistern to the basal cistern with evidence of clot in the fourth and third ventricles. We performed digital subtraction angiography and made the diagnosis of cerebrovascular FMD. Right carotid angiography and left vertebral angiography showed the classic “string-of-beads” pattern with multiple constrictions of the lumen. Left carotid angiography showed a long segment of tubular stenosis. Right vertebral angiography also revealed the “string-of-beads” pattern and a ruptured aneurysm at the intracranial segment,which presented as a diverticulum-like outpouching. The patient was treated with conservative measures but passed away on the 23rd day of hospitalization. An autopsy was not performed. To our knowledge,during the last three decades,there are only four previous reports which showed intracerebral ruptured aneurysms of the vertebral artery or its branch in adults with cerebrovascular FMD. We demonstrate and discuss the radiologic findings here.