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In children with Moyamoya disease, transient ischemic attacks often occur during hyperventilation, and the frequency of attacks usually decreases with advancing age. To elucidate the mechanism of the attacks, the regional cerebral blood flow was measured during rest and/or hyperventilation in children aged 3-16 with Moyamoya disease. Regional cerebral blood flow during rest was significantly higher in younger children with Moyamoya disease, and it progressively decreased with advancing age through childhood. During hyperventilation, regional cerebral blood flow decreased in all the children, although blood flow in younger children was still higher than that in the older children. Nevertheless, transient ischemic attacks were more readily precipitated by hyperventilation in the younger than in the older children. Cerebral metabolic demand is much higher in the first decade of life than in later decades. Therefore, it seems likely that even a moderate reduction in cerebral blood flow can cause metabolic impairment in young children. Such high cerebral metabolic demand may play an important role in the frequent occurrence of transient ischemic attacks in young children with Moyamoya disease.
Tagawa et al. (Tue,) studied this question.