Historically used techniques for assessing CBF and cerebrovascular reserve such as PET and SPECT require exposure to ionizing radiation and are hence undesirable. 12, 14 ⇓– 16 This negative response, termed “steal,” is an independent predictor of ischemic injury and stroke. In the context of steno-occlusive arteriopathy and maximal microvascular vasodilation in response to falling CBF, exhaustion of cerebrovascular reserve and vasodilatory capacity may result in paradoxical reductions in CBF and CVR following a vasodilating stimulus. 13 In vivo assessment of cerebrovascular reserve can be performed by measurement of cerebrovascular reactivity (CVR), defined as a change in CBF in response to vasoactive stimuli such as carbon dioxide. 12 Studies in adults with arteriopathy suggest that impairment of cerebrovascular reserve is associated with an approximate 4-fold increased risk of developing stroke or transient ischemic attacks. 9 ⇓– 11 However, the pathology of the primary arteriopathy is poorly understood.Ī network of lenticulostriate collaterals develops to bypass the primary steno-occlusive arteriopathy, and vasodilation at the level of the capillary bed occurs to maintain cerebral blood flow, resulting in a reduction of cerebrovascular reserve. It confers a life-long risk of recurrent stroke and neurologic injury, and it is associated with early death due to chronic cerebral hypoperfusion and thrombotic vaso-occlusion. It is a progressive steno-occlusive arteriopathy that typically affects the anterior circulation arteries of the circle of Willis. 6 ⇓– 8 Moyamoya disease is a major arteriopathy of childhood.

3 ⇓– 5 More than two-thirds of previously healthy children presenting with their first arterial ischemic stroke have a steno-occlusive arteriopathy, the presence of which predicts recurrence and outcome. 1, 2 Childhood risk factors are multiple and include cardiac disease, sickle cell disease (SCD), arteriopathy, and infection. The incidence ranges from 2 to 13 per 100,000 person-years in developed countries. ABBREVIATIONS: BH breath-hold BOLD blood oxygen level–dependent CV coefficient of variation CVR cerebrovascular reactivity ICC intraclass correlation coefficient SCD sickle cell diseaseĪrterial ischemic stroke remains a major cause of morbidity and mortality in children worldwide.

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