National survey of periventricular leukomalacia in Japan.

BACKGROUND

Clarification of the present status of periventricular leukomalacia (PVL) in Japan.

METHODS

Questionnaires were mailed to the leading neonatal intensive care units (NICU) and rehabilitation centers for children.

RESULTS

The incidence of PVL in the group of surviving preterm infants of gestational ages less than 33 weeks was 4.8-4.9% on ultrasound and 7.7-7.9% on magnetic resonance imaging and/or computed tomography. The incidence of PVL did not decrease between 1990 and 1994. The incidence of PVL in the NICU varied from 0 to 47.1%. Infants from multiple pregnancies had a higher incidence (9.1%) of PVL than those from single pregnancies (6.2%). The proportion of PVL in all patients in rehabilitation centers with cerebral palsy (CP) has increased recently.

CONCLUSIONS

It was roughly calculated that about 750 cases of CP with PVL occurred annually in Japan, thus accounting for about one-third of the total number of cases of CP.