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34 year old male with ALOC.

Chronic occlusive cerebrovascular disease characterized by stenosis/occlusion of terminal ICA and proximal first-order branches

Children and adults may have different clinical presentations

Cerebral ischemic events are the more common presentation in children

Adults experience hemorrhage more commonly

Intracranial hemorrhage occurs in ~60% of adult patients -- intraventricular, intraparenchymal, subarachnoid.

Etiology of ICH remains unclear

Moyamoya vessels thought to be site of rupture in most cases

“fragile” vessels with profound hemodynamic stress

Infrequently accompanied by intracranial aneurysm

Aneurysms occur with an incidence of 3-14% in Moyamoya disease

Major artery aneurysms -- circle of Willis (60%)

“peripheral artery” aneurysms

Moyamoya vessels (lenticulostriate) to BG (20%)

Anterior and posterior choroidal collaterals (20%)

IVH, intraparenchymal hematoma

Peripheral aneurysms are generally considered “pseudoaneurysms”

Case reports of histologically-confirmed saccular aneurysms

? Spontaneous regression.

Yoshida et al. studied 111 moyamoya patients, 28 of which presented with hemorrhage, with a mean follow-up period of 14.2 years

Peak age of initial bleed in 3rd-4th decade

28% rebleed rate within average of 7 years (range 2-20 years)

No clear evidence that revascularization significantly prevents rebleeding

Preventive effect of bypass is expected

Lack of long-term prospective data.