Cerebral hemodynamics as a predictor of stroke in adult patients with moyamoya disease: a prospective observational study

Abstract

Moyamoya disease is an obliterative vasculopathy of the large arteries at the base of the brain. In the US, it most commonly affects women in their 3rd and 4th decades of life, frequently causing ischemic stroke. The natural history of this disorder is not well described. It is very likely that hemodynamic factors play an important role in the risk of future stroke, as has been established in atherosclerotic carotid occlusive disease. The authors describe an ongoing, prospective observational study designed to test the hypothesis that increased oxygen extraction in the cerebral hemisphere beyond the occlusive lesion is a predictor of subsequent risk of ipsilateral stroke in medically treated patients with moyamoya phenomenon. On enrollment, all patients undergo regional measurements of cerebral oxygen extraction fraction (OEF) with PET. Information on baseline clinical, laboratory, epidemiological, and angiographic risk factors are obtained at the time of the PET study. Decisions regarding surgery are made by the treating physicians based on clinical information while being blinded to PET data. Patients undergo follow-up at 6-month intervals to determine the subsequent risk of ipsilateral stroke. All patients will return at 1 and 3 years for repeat PET studies. Secondary, exploratory, aims of this longitudinal and blinded study are to determine other predictive factors for stroke in this population; to determine preliminary estimates of the effects of different medical treatment regimens in this population; to determine the temporal changes in hemodynamic impairment in medically treated patients; to determine the effects of surgery on hemodynamic impairment in the subset of patients who undergo surgical revascularization; and to obtain estimates of surgical complication rates for patients with and without hemodynamic impairment.

Figures

Fig. 1

Positron emission tomography scans demonstrating asymmetrical OEF abnormality and improvement following a unilateral EDAS procedure in a 31-year-old woman presenting with an episode of right-sided weakness. Angiography had demonstrated bilateral internal carotid artery disease with moyamoya collaterals. Upper: Preoperative images demonstrating a focal area of reduced CBF (arrow) in the left motor cortex with preserved oxygen metabolism (CMRO2). A compensatory increase in OEF is present (arrow). Regional analysis of the middle cerebral artery territories bilaterally, using the same 7 spherical regions of interest as used in the STLCOS and proposed for the present study, demonstrated increased OEF by hemispheric ratio (1.10) and absolute values (0.470), when compared with values from 18 normal control patients. The patient underwent an uncomplicated unilateral EDAS procedure. Lower: Repeat PET images obtained at 12 months showing improvement in CBF and OEF (arrows). CBV = cerebral blood volume.