A nationwide survey of bilirubin encephalopathy in preterm infants in Japan.

OBJECTIVES

To examine the clinical characteristics of bilirubin encephalopathy in preterm infants (pBE) in Japan.

METHODS

We performed a two-step nationwide questionnaire survey. The initial survey determined the number of children with pBE. Using a structured questionnaire, the second survey clarified the clinical manifestations and characteristics of children with pBE, including the perinatal history, neonatal complications, neurological features, verbal communication, diet, and magnetic resonance imaging (MRI) and auditory brainstem response (ABR) findings.

RESULTS

The initial survey included 190 pBE infants, indicating an incidence of approximately 10 per year. Clinical information was available for 142 of them. The median gestational age was 26 weeks and the median birthweight was 883 g. As to neonatal complications, 20% had none, 25% had one complication, 54% had two or more. Head control was observed in 45% and functional gait in 8%. Purposeful hand use was seen in 41% of patients and verbal communication in 40%. MRI showed T2 hyperintensities in the globi pallidi in 111 of 136 patients, especially between 7 and 18 months of corrected age. ABR abnormalities were present in 88 of 117 patients.

CONCLUSIONS

pBE was infrequent but constantly observed during the study period, especially in very preterm infants, even in those with no severe neonatal complications. Severely impaired gross motor function and relatively preserved manual function and verbal communication were characteristic. MRI and ABR abnormalities will facilitate diagnosis.