Multimodal neurophysiological monitoring in healthy infants born at term: normative continuous somatosensory evoked potentials data.

Aim: To describe accurate, standardized 1h-multimodal neurophysiological monitoring (1h-MNM), while simultaneously recording VEEG, aEEG, and SEP-C bilaterally from median nerves, and to collect neonatal normative SEP-C data related to behavioural states.

Method: Twenty healthy, term newborn infants (13 males, 7 females; gestational age 37-42wks; mean 39.6wks, standard deviation [SD] 1.3wks) underwent 1h-MNM within 2 days of life, with focus on recording of the SEP-C (band-pass setting 1-100 Hz, rate of stimulation 1.1 Hz, 50 alternate stimuli).

Results: 1h-MNM was easily obtained with identification of cervical (N13) and cortical (N1, P1) SEP-C responses in all infants. SEP-C minimal and maximum N1 latencies/N1-P1 amplitudes were identified, bilaterally, during periods of spontaneous sleep active-quiet-active (AS-QS-AS) and quiet-wakefulness. Minimal latencies and amplitudes occurred in 60% of active sleep/quiet-wakefulness, with the maximums in 70% of quiet sleep. The SEP-C mean values were latencies of N13=13.6ms (SD 1.4ms) and N1=33.6ms (SD 3.9ms) to 34.2ms (SD 4.8ms) in left and right hemisphere respectively; central-conduction-time (CCT) (N13-N1), 20.0ms (SD 4.3ms) to 20.6ms (SD 4.8ms); N1-P1 amplitude=4.6ms (SD 2.7ms) to 3.8μV (SD 2.2μV).

Interpretation: 1h-MNM can record simultaneously VEEG/aEEG/SEP-C in newborn infants, showing the modulation of SEP cortical responses in relation to behavioural states in all infants studied using an appropriate neonatal method. We emphasize the importance of obtaining neonatal SEP-C normative data to better identify pathological findings in neonatal brain injury.