Prognostic value of flash visual evoked potentials in preterm infants

Abstract

This paper investigates the prognostic value of flash visual evoked potentials (VEPs) recorded in preterm infants at birth and at term age with respect to severe neurological outcome. Flash VEPs were recorded in 81 preterm infants at birth (i.e. <35 weeks' gestation) and repeated in 56 of these infants at term age. The preterm infants were assigned to either a healthy or at-risk subgroup based on clinical birth factors. Normal ranges of flash-VEP latencies, amplitudes, and number of components present were obtained from the subgroup of healthy preterm infants and from 68 term infants tested postnatally. The flash-VEP results of the entire preterm group were compared with the normal ranges and any abnormalities noted. Seven preterm infants in the at-risk group died, six of whom had abnormal flash VEPs before term age. Of the five infants from the at-risk group diagnosed with cerebral palsy (CP), three had abnormal flash VEPs before term age. Thus the sensitivity and specificity of the flash VEP with respect to survival was 86% and 89% respectively, and with respect to the development of CP was 60% and 92%. The abnormal features of the flash VEP associated with adverse outcomes comprised a delayed N3 component before term age and the absence of a positive component (P2) at term age.

Flash Visually Evoked Potentials in the Newborn and their Maturation During the First Six Months of Life

“…Despite the high morphological variability observed, mainly in the newborn, our results concerning the latencies and amplitude of the major flash visually evoked responses, resemble those of other authors [15,[22][23][24][25].…”

“…As noted by other authors [15,20,29], P2 was the only component invariably present in all the newborn's records, therefore the only response suitable for clinical purposes. The low right to left P2 latency and amplitude differences allow us to make interocular comparisons if we suspect unilateral problems.…”

“…N3 component, recorded in 42% of the newborns is a primitive response, characteristic of the healthy preterm infants emerging from 24 weeks GA [15,[26][27][28]. This response is preceded or replaced in the normal newborn at term by a positive component P2.…”

“…In spite of the F-VEP limitations, several studies have proved their usefulness in the assessment of acute-onset cortical blindness and as a prognosis tool, when they are performed serially in the early postnatal period, in the cases of anoxic encephalopathy secondary to neonatal anoxia [9][10][11][12][13][14][15]. Their usefulness increases when later on visual development is monitored through the P-PEV, which allows us to carry out a more accurate assessment of the visual processing [16].…”

Pediatric clinical visual electrophysiology: a survey of actual practice

“…The VEP stimuli and data acquisition conditions promulgated in the ISCEV standard are generally suitable for testing all but perhaps the very youngest of infants. In infants under 12 weeks of age and prematurely born infants, VEP waveforms may be prolonged beyond the standard 250 ms analysis time [45][46][47][48][49].…”