Somatosensory evoked fields at 36 weeks' gestation in preterm infants: A pilot study of thalamocortical maturation.

OBJECTIVE: Somatosensory evoked fields (SEF) recorded using magnetoencephalography enable non-invasive measurement of the cortical activity within the afferent somatosensory pathway. Because MRI studies suggest that delayed myelination and damage to the white matter contribute to adverse effects on neurological development in preterm infants, early functional markers of brain maturation are of particular interest. METHODS: In this single-center pilot study, SEFs were recorded using tactile stimulation in 13 preterm infants examined at 36 weeks' gestational age (GA) and 8 term infants examined at 40 weeks' GA. Latencies to the first cortical deflection in the somatosensory cortex were analyzed and compared across gestational ages at recording and between very preterm (26-31 weeks of GA at birth) and moderate/late preterm infants (32-36 weeks GA). RESULTS: SEF waveforms were obtained in all infants. Latencies were longer in preterm infants at 36 weeks' GA compared to term infants at 40 weeks' GA and decreased significantly with advancing GA. No significant latency differences were found between very preterm and moderate/late preterm infants at 36 weeks' GA. CONCLUSIONS: MEG-based SEF recording is feasible in preterm infants at 36 weeks' GA. SEF latency did not provide evidence of a significant delay in somatosensory maturation in very preterm compared with moderate/late preterm infants and does not support the hypothesis of a delayed myelination in very preterm infants. SIGNIFICANCE: Although limited by sample size, single time-point measurements, and lack of magnetic resonance imaging (MRI), our study lays a foundation for future MEG investigations of premature infants in early life.