[Moyamoya disease]

To describe the clinical manifestations and to summarise the knowledge currently available about the epidemiology, physiopathology, histopathology, diagnosis and treatment of moyamoya disease.

Moyamoya disease is produced by the spontaneous, progressive occlusion of the circle of Willis with the simultaneous appearance of natural intracranial and extra-intracranial collaterals. Both children and adults can be affected and it is to be found not only in Asia but also in Europe and America, although the frequency is unknown. Its primary lesion is a thickening of the tunica interna in the distal segment of the internal carotids, initially within the anterior portion of the circle of Willis. This results in the appearance of collateral vessels, which are first intracranial (moyamoya vessels) and then extracranial, to offset the critical reduction in regional cerebral blood flow. The most common clinical manifestation is motor-type ischaemic episodes, although it may also be accompanied by intracerebral haemorrhages. It can be diagnosed by means of suitable morphological and functional studies, such as cerebral pan angiography and xenon-CT, in patients with a founded clinical suspicion. Neurosurgical revascularisation is to date the most widely accepted treatment and can bring about a permanent clinical cure.

Moyamoya disease is a rare pathology that can be successfully treated using cerebral revascularisation, provided a timely diagnosis is reached and in indicated patients. Such therapy makes it possible to prevent the repetition of ischaemic events or haemorrhages that usually bring about severe limitations in the individual's personal development.