Presented at the Neonatal Society 2017 Spring Meeting.
Panayotidis I1, Jones L1, Fabrizi L1, Fitzgerald M1, Meek J2, Verriotis M1
1 Dept. Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
2 Elizabeth Garrett Anderson Obstetric Wing, University College London Hospital, London, WC1E 6DB, UK
Background: Previous EEG studies (1) have identified a nociceptive-specific event-related potential (nERP) in the newborn brain following a clinically-required noxious heel lance. This nERP is maximal at the vertex (Cz and CPz electrodes) and well localised on a group average basis (2). However, we observed that the distribution of this response across the scalp could differ between subjects. Here we test the hypothesis that there is significant individual variability in the topographical distribution of the infant nERP and that this depends upon gestational age (GA).
Methods: Participants were 96 babies (23-42 weeks GA; 30-43 weeks corrected GA) recruited between 2007 and 2016. Brain activity was recorded using 9-22 EEG electrodes placed according to the international 10:20 system. The noxious stimulus was a clinically required routine heel lance, which was time-locked to the EEG recording. Ethical approval was obtained from the UCLH ethics committee and informed written parental consent was obtained prior to each study. This work was supported by the Wellcome Trust (090245/Z/09/Z), the Medical Research Council (MR/M006468/1), and the NIHR UCLH Biomedical Research Centre.
Results: There was considerable individual variability in the topographical distribution of the nERP. In 54/96 babies (56%), the nERP could be identified at 9 or more electrodes and was considered to be widespread. The incidence of widespread nERP was greater in babies born and studied at premature age (Prem-Prem; <37 weeks GA; 25/37, 68%) compared to babies born and studied at term age (Term-Term; 37+ weeks GA; 14/33, 42%). Chi-square analysis indicates a significant effect of gestational age (χ2 = 4.47, p=0.053). There was no difference in the incidence of widespread nERP between babies born prematurely and studied at term age (Prem-Term) and the Term-Term babies (12/19, 63% vs. 14/33, 42%; χ2 = 2.1, NS).
Conclusion: A widespread pattern of distribution of the nERP is common in premature babies, with the response becoming more localized with increasing GA. A widespread nERP is likely to be due to the structural and functional immaturity of the premature brain and indicates age-related changes in cortical pain processing in prematurity.
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1. Slater et al 2010. Eur J Pain 14: 321-326
2. Fabrizi et al. (2016). Scientific Reports, 6:28642.