内頸動脈に水かき状狭窄（Internal Carotid Artery Web）を認めた線維筋性形成異常症の1例

Fibromuscular Dysplasia with an Internal Carotid Artery Web on the Angiograms

I．はじめに

　頸部頸動脈の動脈硬化による狭窄や潰瘍が脳虚血発作の責任病巣となることはよく知られている．一方，線維筋性形成異常症（FMD）は偶然に発見されることが多く，脳虚血発作を伴うものは比較的稀とされている^2）．また，FMDの典型例では血管の全周にわたる輪状の狭窄が第2頸椎の高さのレベルに好発し，血管撮影上string of beadsの像を示すが，FMDのなかには，粥状硬化症と同様，内頸動脈が総頸動脈より分岐した直後に好発し，動脈壁の一部に鳥の趾の水かき（web）に似た狭窄像を示すものがある．このような症例の報告は稀であり，また，今までの報告例の多くが脳虚血症状を伴っており，手術により改善がみられている．われわれは血管撮影上web状狭窄を示し，¹²³I-IMP SPECTにより，術後血流改善が認められたFMDの特殊型を経験した．

A 58-year-old woman experienced a transient right-sided hemianopsia. She also had difficulty finding words and trouble naming parts of objects.

On admission, three days later, there were no signs of residual neurological deficit. Laboratory studies showed findings of neither diabetes mellitus, hypertension nor cardiac disease. Her serum cholesterol level was nor-mal. No bruit was heard over the head and neck.

Preoperative angiograms showed a discrete web (sep-tum) at the left internal carotid origin (Fig. 2). ¹²¹-IMP SPECT revealed a decreased areas of perfusion mainly in the left middle cerebral artery distribution (Fig. 3A). A reconstructive operation was performed.A firm discrete nonatherosclerotic ridge (septum) protruding into the vessel lumen was resected. Microscopic ex-amination of the surgical specimen demonstrated intim-al fibroplasia, a rare subtype of fibromuscular dysplasia (FMD).

Postoperatively, hypoperf used areas in SPECT were improved (Fig. 3B). The patient has been free of symp-toms to the present time (for about one year). In addition to the rarity of the lesion, the available data suggest that web-like subtype of FMD is apt to be associated with an increase in the risk of hemodynamic compromise and thromboembolism. Surgical therapy is recommended, especially for symptomatic patients.