Researchers at Seoul National University Children’s Hospital, Korea, analyzed the clinical characteristics and prognostic factors for outcome of 410 pediatric cases of moyamoya disease (MMD) after bypass surgery. Patients’ ages were 0-3 years in 15%, 4-6 in 27%, and 7-18 years in 58%; sex M/F ratio was 1:1.3. Cases were familial in 12%. Clinical manifestations included transient ischemic attacks in 56%, infarction in 39%, headache in 33%, seizure 19%, involuntary movements 4%, and hemorrhage 3%. Unilateral MMD at initial diagnosis in 53 progressed to bilateral involvement in 24 (45%) within 2 years. CT/MRI showed no infarction in 44%, and major infarction in 39%. SPECT showed decreased perfusion in 60% and decreased vascular reserve in 84%. Neurocognition test was abnormal in 93%, and IQ <90 in 24% (>90 in 76%). Surgery consisted of bilateral encephaloduroarteriosynangiosis augmented by bifrontal encephalogaleo/periosteal synangiosis. The interval between onset of symptoms and surgery averaged 21 months (range, 1 week to 108 months). In cases benefited, symptoms usually resolved in an average of 4.3 months. Surgical outcome was excellent in 66%, good in 15%, fair in 15%, and poor in 4% of patients. Infarction at presentation was associated with unfavorable clinical outcome, and decreased vascular reserve only on SPECT indicative of a favorable outcome (81% cases). Early diagnosis and surgical intervention before irreversible hemodynamic change occurs are essential to obtain a favorable outcome. 
COMMENT. Moyamoya disease is a largely Korean or Japanese cerebrovascular disease of internal carotid arteries with compensatory vascular network at the base of the brain. Repeated transient ischemic attacks are common presenting symptoms in children and intracranial hemorrhage in adults. Surgery to establish adequate collateral circulation is effective in ischemic cases without infarction. Outcome was favorable in 81% of the above large series of pediatric cases. Infarction at the time of diagnosis of MMD is predictive of a 3-fold increased risk of unfavorable surgical outcome, whereas decreased vascular reserve only with normal basal perfusion on SPECT has a 14-fold increased frequency of favorable outcome. Long-term follow-up is recommended in unilateral cases to monitor potential progression and bilateral involvement.