Clinico-epidemiological features of infantile hydrocephalus in Japan.

In 1988, a nationwide survey was conducted in Japan, in order to examine the prevalence and clinico-epidemiological features of hydrocephalus that developed before 1 year of age. The study was based on questionnaires that were sent to all hospitals in Japan with more than 200 beds. There were 1435 patients who were eligible for the analysis. They were born before 1987 and diagnosed as having infantile hydrocephalus. Approximately two-thirds of the patients had primary hydrocephalus. Neural tube defects were the most frequent cause of the primary hydrocephalus and common among full-term infants. On the other hand, secondary hydrocephalus occurred more often in preterm infants, mainly following intracranial hemorrhage. Intracranial hemorrhage as a cause of hydrocephalus increased over the year, while the incidence of hydrocephalus secondary to intracranial infection decreased during the same period.