[Incidence patterns of cerebral palsy in Shiga, Japan, 1977-1986--an epidemiological study]

An epidemiological study of cerebral palsy (CP) in Shiga Prefecture, was performed by reviewing medical records of the Medical Center for Children in Shiga (MCCS) and related hospitals. The total number of CP patients identified at 6 years old was 202 (117 boys and 85 girls) who were born during the ten years period between 1977-1986. The average prevalence of CP in Shiga Prefecture was calculated as 1.09 per 1,000 school children aged 6 years. The prevalence of CP was 9 fold among low birth weight infants (1,500-2,499 g) and 41 fold among very low birth weight infants (< 1,500 g), compared with that of mature infants (> or = 2,500 g). One hundred and thirty nine cases (69%) were term infants, and 63 cases (31%) were preterm. Etiology of 139 term cases was considered to be prenatal in 50 cases (35%), perinatal in 37 cases (26%), postnatal in 3 cases (2%) and untraceable in 49 cases (35%), whereas prenatal in 12 cases (19%), perinatal in 7 cases (11%), and untraceable in 44 cases (70%) of 63 preterm cases. The prevalence rate of CP was fairly constant throughout the whole period of 1977-1986, but the term cases with perinatal etiologies significantly decreased in the period of 1982-1986, compared with those in the preceding period of 1977-1981. Children born weighting less than 1,500 g significantly increased in the later period. The improvement of perinatal care seems to play a major role on these changes. Sixty percent of term cases and 20% of preterm cases were considered to be due to prenatal factors which could not be prevented by the improvement of perinatal care.