[A case report of fibromuscular dysplasia presenting symptoms like moyamoya disease: "string of beads" appearance of the pericallosal artery].

We report a case of fibromuscular dysplasia (FMD) presenting a transient ischemic attack (TIA) like Moyamoya disease. The patient, a 16-year-old woman, had recurrent attacks of right hemiparesis induced by hyperventilation. Neurological examinations revealed no abnormality. Angiography showed severe stenosis of both anterior cerebral arteries at the proximal portion with "string of beads" appearance in the left pericallosal artery, and tubular stenosis of the left internal carotid artery at the level of the second cervical vertebra. Renal artery stenosis was not seen. A cerebral-blood-flow (CBF) study with 133Xe SPECT showed marked reduction of CBF in the left cerebral hemisphere at times of hyperventilation. Extracranial-intracranial bypass surgery was performed and histological examination of the superficial temporal artery (STA) revealed intimal fibroplasia which was compatible with FMD. Postoperative angiography showed good filling of the middle cerebral arteries from the STA. The patient has had no recurrence of TIA for a year since the operation. CBF study showed mild low CBF in the region of the left anterior cerebral arterial circulation at hyperventilation. There is no report of intracranial FMD presenting an ischemic symptom induced by hyperventilation. Clinical diagnosis of Moyamoya disease should be made carefully when extracranial vascular lesion accompanies it.