Somatosensory Evoked Potentials (SEP) in Term Newborns with Perinatal Hypoxic-Ischemic Encephalopathy (HIE)

Aim: The aim of this work was o evaluate the diagnostic value of somatosensory evoked potentials (SEP) in newborns developing perinatal HIE. Patients and Methods: Our prospective study included ten healthy newborns (postconceptional age 38–41 weeks) and ten asphyxiated infants (postconceptional age 38–42 weeks). Perinatal asphyxia was defined as umbilical artery pH -10 mmol/l and development of HIE which was evaluated according to the criteria of Sarnat et al. (1976). SEP were performed at the median chronological age of 8.5 days (controls) and 6.0 days (asphyxia group). Cortical responses were recorded at C 3'/C 4' against Fz (international 10–20 system) and nuchal responses from the second cervical vertebra against a frontolateral electrode (contralateral to the stimulation; stimulation frequency 1.1Hz, stimulus duration 100µs). A 1–3000Hz filter bandpass with 50Hz knock-out filter was used. At least two (median: four) recordings were performed. The median number of stimuli was 128. Cortical latency (N20) and central conduction time (CCT, interpeak latency N13-N20) were analyzed for both groups. Results (mean±SD): Seven infants developed severe HIE (stage 2–3). There was no significant difference in the degree of metabolic acidosis between patients with HIE stage 2–3 (pH 7.0±0.1, BE –18±6 mmol/l) compared to mild HIE (pH 7.0±0.1, BE -17±2 mmol/l). Latencies were significantly prolonged in asphyxiated infants compared to healthy controls: N20, 52.0±7.0 ms in patients with HIE and 38.3±4.7 ms in healthy newborns (p<0.01); CCT, 40.8±8.0 ms and 28.2±4.8 ms, respectively (p<0.01). There was a trend towards longer latencies in infants with HIE stage 2–3 compared to infants with HIE stage 1. No significant relation between UA pH values and SEP latencies could be found in the HIE group. Conclusions: As shown by our data, SEP during early postnatal period are a useful, non-invasive and practicable additional early diagnostic tool in term newborns developing HIE. Our own reference data were in accordance with reports in the literature.