Relationships of age, rCBF and transient ischemic attacks in children with occlusion of the circle of Willis

In children with occulsion of the circle of Willis, so called Moyamoya disease (MMD), the most common clinical manifestation is transient ischemic attacks (TIAs). TIAs are often encountered during crying, blowing balloons or eating hot foods seemingly relating with hyperventilation. Occurrence of TIAs is most frequent in the first decade, and somehow attacks tend to cease after advance of age. The purpose of this study is to clarify whether age factor is participated with frequent occurrence of TIAs in MMD children. Materials and Methods : Thirteen MMD children with ages ranging from 3 to 16 years were subjected in this study. These children had recurrent TIAs since 2 to 10 years of age but no neurological deficit at the time of study. In these children, regional cerebral blood flow (rCBF) was measured by 133Xe inhalation methods during resting state and/or hyperventilation; and relationships of age, rCBF and frequency of TIAs were analyzed. The rCBF was measured also in 29 adult controls who had TIAs but no MMD. Results : At the time of this study, all MMD children below 10 years of age had frequent repetition of TIAs, while 3 of 5 older children had no TIA for the last 6 months to 6 years. Thus, the lower the age, the more frequent the occurrence of TIAs. In 12 children, TIAs were often precipitated by hyperventilatory behaviors, such as crying. In 3 children with 5 to 7 years of age, TIAs occurred during voluntary hyperventilation which was performed at the time of EEG recording. The rCBF (ISI) values in MMD children measured during resting state were 64.3 ± 10.2, and those in adult TIA patients were 45.2 ± 4.3. The former was significantly higher than the latter (p