Moyamoya

Occurs in both children and adults, peak age at 5 y and 40 y, respectively

Female-to-male ratio of 1.8:1

Highest incidence in Japanese and Asian populations; familial occurrence 10%

Stroke

Hypocarbia and hypercarbia

Adequate cerebral blood flow

Hypotension

Hypothermia

In Japanese, moyamoya means “puff of smoke,” which describes the angiographic appearance of collaterals between internal and external carotid arteries.

Chronic progressive cerebrovascular disease consisting of concentric stenosis or occlusion of the distal internal carotid arteries and large vessels of the circle of Willis with prominent basal collateral vessels.

Histopathology shows eccentric intimal thickening by fibrous tissue, smooth muscle cell hyperplasia, and luminal thrombosis

The most common presentation in children and adults is ischemic stroke.

In contrast to children, adults may also present with intracranial hemorrhage.

TIA, headache, and seizures are other presenting symptoms.

Symptoms are precipitated by activities that involve hyperventilation that results in hypocarbia (e.g., crying, exercise).