Neural conduction abnormality in the brain stem and prevalence of the abnormality in late preterm infants with perinatal problems

Neurodevelopment in late preterm infants has recently attracted considerable interest. The prevalence of brain stem conduction abnormality remains unknown. We examined maximum length sequence brain stem auditory evoked response in 163 infants, born at 33–36 weeks gestation, who had various perinatal problems. Compared with 49 normal term infants without problems, the late preterm infants showed a significant increase in III–V and I–V interpeak intervals at all 91–910/s clicks, particularly at 455 and 910/s (p < 0.01–0.001). The I–III interval was slightly increased, without statistically significant difference from the controls at any click rates. These results suggest that neural conduction along the, mainly more central or rostral part of, auditory brain stem is abnormal in late preterm infants with perinatal problems. Of the 163 late preterm infant, the number (and percentage rate) of infants with abnormal I–V interval at 91, 227, 455, and 910/s clicks was, respectively, 11 (6.5 %), 17 (10.2 %), 37 (22.3 %), and 31 (18.7 %). The number (and percentage rate) of infants with abnormal III–V interval at these rates was, respectively, 10 (6.0 %), 17 (10.2 %), 28 (16.9), and 36 (21.2 %). Apparently, the abnormal rates were much higher at 455 and 910/s clicks than at lower rates 91 and 227/s. In total, 42 (25.8 %) infants showed abnormal I–V and/or III–V intervals. Conclusion: Conduction in, mainly in the more central part, the brain stem is abnormal in late preterm infants with perinatal problems. The abnormality is more detectable at high- than at low-rate sensory stimulation. A quarter of late preterm infants with perinatal problems have brain stem conduction abnormality.