Evaluation of somatosensory cortical processing in extremely preterm infants at term with MEG and EEG

• Secondary somatosensory cortex (SII) responses complement neonatal neurological evaluation in predicting neurodevelopmental outcome in extremely preterm infants.
• SII responses can be measured with MEG as well as with the routinely available bedside EEG-SEP recordings.
• Use of sensory responses as a part of routine EEG studies holds promise to significantly expand early neurophysiological evaluation of neonates after adversities.

ObjectivePrior studies on extremely preterm infants have reported long-term prognostic value of absent secondary somatosensory cortex (SII) responses in magnetoencephalography (MEG) at term. The present work (i) further examines the potential added value of SII responses in neonatal neurological evaluation of preterm infants, and (ii) tests whether SII responses are detectable in routine neonatal electroencephalogram complemented with median nerve stimulation (EEG-SEP).MethodsAltogether 29 infants born <28 gestational weeks underwent MEG, MRI, and neonatal neurological examination at term age, and Hempel neurological examination at 2-years corrected age. Term-age EEG-SEP was available for seven infants.ResultsWhile in neonatal neurological examination severely abnormal finding predicted unfavorable outcome in 2/2 infants, outcome was unfavorable also in 3/9 (33%) moderately abnormal and in 5/18 (28%) mildly abnormal/normal infants. Of these eight infants four had unilaterally absent SII responses in MEG, compared with only two of the 24 infants with favorable outcome. Furthermore, SII responses (when present in MEG) were also usually detectable in EEG-SEP.ConclusionsComplementing clinical EEG recording with SEP holds promise for valuable extension of neonatal neurophysiological assessment.SignificanceMultimodal study of EEG and sensory evoked responses is informative, safe, and cheap, and it can be readily performed at bedside.