Incidence and prognosis of central nervous system infections in a birth cohort of 12,000 children.

All types of central nervous system (CNS) infections were investigated in a 1966 birth cohort of 12,000 children from Northern Finland followed up from birth to the age of 14. 174 CNS infections occurred in 167 children, 110 boys and 64 girls. The annual incidence of bacterial CNS infections was 36.3/100,000 and that of viral infections 688.0/100 000. It is concluded that bacterial CNS infections were recorded very fully but only 2/3 of the viral infections could be traced, even though the more severe cases were quite well documented. 8/55 children (14.5%) with bacterial meningitis died; the corresponding figure for viral encephalitis and meningitis (excluding mumps) was 3/67 (4.5%). 17/55 (30.9%) developed mental retardation, epilepsy, cerebral palsy or hearing defect or some combination of these after bacterial CNS infection, and 9 (8.1%) after viral infection. The difference with respect to the children who had not experienced CNS infection was statistically significant only for the bacterial infection cases. CNS infections explained 7.6% of all deaths from 28 days to 14 years, 3% of the handicapping cases of cerebral palsy, mental retardation and epilepsy or some combination of these, and 6.6% of the hearing defects.