Evaluation of maturation and function of visual pathways in neonates: role of flash visual-evoked potentials...

The purpose of our study was to establish the guidelines for interpreting neonatal flash visual-evoked potentials (FVEPs) by examining the correlation between maturation of the waveforms and conceptual age (CA). We retrospectively analyzed 220 consecutive neonatal FVEPs performed on premature and full-term infants. The CA of the participants ranged from 28 to 52 weeks. The FVEPs were categorized into 6 groups according to CA: 28 to 31+ weeks, 32 to 35+ weeks, 36 to 39+ weeks, 40 to 43+ weeks, 44 to 47+ weeks, and 48 to 52 weeks. The data were analyzed in each group and compared among these 6 groups. The waveforms changed from 28 weeks to 52 weeks of CA. In the CA age range 28 to 31+ weeks N3 was well visualized, followed by P3. The morphology of P2 including both latency and amplitude became prominent starting from CA age range 32 to 35+ weeks. The triphasic waveform with clear negative-positive-negative components (N2-P2-N3) presented after 32 weeks. Mean P2 latencies decreased steadily with increasing age. Mean amplitudes of all waveforms (P2-N3 and N3-P3) varied except that of N2-P2 which increased steadily with CA. We conclude that FVEPs can be useful in the evaluation of maturation and function of the visual pathway in neonates. The FVEP is abnormal when the waveforms N3 and P3 are nondetectable in neonates at 28 weeks of CA or older; and when the waveform P2 is non-detectable, or has low amplitude or prolonged latency, in neonates at 36 weeks of CA or older.