[Cerebral infarction attributable to cerebrovascular fibromuscular dysplasia]

Fibromuscular dysplasia (FMD) is a noninflammatory, nonatheromatous segmental angiopathy. The renal arteries are affected most commonly, followed by the internal carotid and vertebral arteries. FMD of the internal carotid and vertebral arteries usually occurs in the extracranial portions and is mostly observed at the level of the second cervical vertebra. FMD of the intracranial arteries is rare, but tends to occur in children and young adults. FMD is more common in females than in males, and it is often observed in middle-aged women. Although the etiology of FMD is not well understood, several mechanisms have been proposed, such as genetic predisposition, hormonal factors, and arterial wall ischemia. The pathology of FMD is characterized by smooth muscle hyperplasia or thinning, elastic fiber destruction, fibrous tissue proliferation, and arterial wall disorganization. Cerebrovascular fibromuscular dysplasia (cFMD) is relatively rare in Japan but is regarded as one of the cardinal causes of stroke in the younger population. cFMD without complications causes nonspecific symptoms such as headache or vertigo, but when it results in an arterial dissection or aneurysm, it leads to cerebral infarction or subarachnoid hemorrhage. Conventional angiographic findings mostly reveal a pattern called the "string of beads", which is pathologically correlated to medial fibromuscular dysplasia. Doppler echography, computed tomography and magnetic resonance angiography (MRA) may be useful for detecting cFMD lesions in some cases. MRA should be performed to rule out the presence of intracranial aneurysms. Antiplatelet and anticoagulation agents are prophylactics against cFMD complications. Surgical treatments such as graduated intraluminal dilatation had previously been the mainstays for treating cFMD. Percutaneous transluminal angioplasty with or without stenting has now become the preferred invasive treatment for symptomatic cFMD.