Neurosurgeons at the Hospital for Sick Children and Western Hospitals, Toronto, Canada, review their experiences during a 6 month to 15 year follow up of 25 children with moyamoya disease 15 or whom underwent revascularization procedures. Five patients had superficial temporal artery-middle cerebral artery (STA-MCA) bypass procedures and 13 underwent encephalo-duro-arterio-synangiosis (EDAS), a procedure expected to induce collateral branches to sprout from the STA.
Of the untreated cases, 75% developed permanent neurological sequelae, including seizures, hemiparesis and mental retardation, and 2 died. Among the 13 treated cases, 10 were neurologically intact and the remainder were improved. The STA-MCA was the procedure of choice in older children whereas EDAS, including opening of the arachnoid, a simpler technique, gave good results and was preferred in infants and young children. The authors suggest that all pediatric patients be offered the benefit of early surgical treatment before permanent neurological deficits have developed. 
COMMENT: Moyamoya, a Japanese term meaning hazy or misty like a “puff of smoke“, describes the angiographic appearance of the net-like collateral circulation that develops at the base of the brain as a result of stenosis of the distal internal carotid artery and its branches. Moyamoya disease has been classified in two forms: (1) a “primary“ idiopathic nonprogressive form with alternating hemiplegia, predominantly in girls of Japanese origin, often familial and representing a hereditary malformation of the elastic lamina of the cerebral vasculature, and (2) an “acquired“ usually progressive form in both children and adults with varying underlying diseases. The diseases associated with moyamoya have included neurofibromatosis, basal meningitis, hypertension, atherosclerosis, myopathy, sickle-cell anemia, Fanconi’s anemia, type 1 glycogenosis, congenital heart disease, Down’s syndrome, and conditions requiring radiation therapy. The postradiation pathogenesis was reported by Drs. Rajakulasingam, Cerullo, and Raimondi at Northwestern UMS , one case occurred in the present series, and a patient of mine, a girl aged 16, developed the syndrome following irradiation of the neck for Hodgkin’s disease.
The present authors point out that the early concepts of moyamoya disease as a relatively benign disorder in Japanese girls have been modified in recent reports. The sexes were equally affected and the majority of patients were Caucasian in their series. The clinical course depends on the rapidity and extent of vascular occlusion and the ability to develop a collateral circulation. The progressive nature and serious sequelae of cases left untreated are stressed.