Altered autonomic control in preterm newborns with impaired neurological outcomes

Very preterm newborns are at high risk of neurological injury. The objective of this work was to study the impact of neurological aggression on the autonomic nervous system. We studied polysomnography recordings, at term corrected gestational age, for 38 preterm infants born at less than 28 weeks or weighing less than 1 kg. These infants were seen by a neuropediatrician, average age at follow up was 54.4 months. We created two groups: one with children who did not have any neurological disorder, including cerebral palsy (CP), language or mental retardation, visual or hearing disability, and attention disorder; the second group contained children with at least one of these impairments. From the polysomnography recordings, using coarse-graining spectral analysis, we compared heart rate variability indices between preterm infants with normal and abnormal neurological outcomes. Twenty infants had an impaired neurological outcome. Regarding the clinical characteristics, there were more babies born from smoking mothers (p = 0.025), with early-onset neonatal sepsis (p = 0.04), and abnormal results on cerebral magnetic resonance imaging (p = 0.014) in the group with impaired neurological outcomes. Spectral parameters were significantly different between active and quiet sleep. Total powers, harmonic and non-harmonic powers, high frequency and low frequency powers were higher in active sleep compared with those in quiet sleep. Preterm babies with impaired neurological development, in particular those with CP, had lower total power and non-harmonic power especially in active sleep than those with normal neurological outcome. These findings suggest that, in very preterm infants, perinatal neurological injuries could be associated with abnormal maturation of the autonomic nervous system.