[Status of severely mentally and physically handicapped children of school age in Nagano prefecture].

Prevalence rate and etiology were studied in severely handicapped children of school age in Nagano prefecture as of July, 1994. Severely retarded children were defined as those whose IQ's were lower than 35 and who were unable to walk. The total number of severely retarded children was 165. The prevalence rate was 0.71/1000, 90% of them being in class 1 or 2 of Oshima's classification (bedridden or unable to sit alone and with IQ less than 20), and 26% being cared for at home. Their average gestational age was 38.5 weeks, and the average birthweight 2,772 g. At birth none of them had extremely low birth weight. Etiology of the handicaps was classified as follows; congenital 26.1%; maternal infection 3.0%; prenatal 3.6%; perinatal 27.3%; postnatal 13.9% and unknown 26.1%. Asphyxia decreased gradually but the number of low birth weight premature infants increased. When postnatal etiologies were excluded, the patients with unknown etiology occupied 30.3%, 23.3% of them being light-for-dates baby. The examination of the case histories revealed that causes of unknown etiology are prenatal. If we add unknown etiology to congenital, maternal infection, and prenatal etiology, the prenatal origin is 68%.