Sweep Visual Evoked Potentials in Infants With Infantile Spasms Before and During Vigabatrin Treatment

Abstract

Abstract: : Purpose: To investigate the effect of vigabatrin on contrast sensitivity and visual acuity in infants with Infantile Spasms (IS). Methods: Sweep visual evoked potentials were used to assess contrast sensitivity (CS) and visual acuity (VA) in 14 infants (3mos - 25mos, median 7 mos) with IS, pre initiation of vigabatrin (baseline). Data from 9 of these infants (8mos - 25mos, median 9.5 mos) were compared with historical sweep VEP data from 6 children (15mos - 18mos, median 17 mos) with normal vision. Comparisons were made also between 8 infants from the baseline population and this same population after 5 months on vigabatrin, using paired t-test analysis. Baseline results were also compared with historical data of age-similar children on vigabatrin: (1) showing NO signs of retinal toxicity (n =12) and (2) showing signs of toxicity (n=2). Results: A two-tailed t-test showed that infants (n=9) with IS had a significant peak contrast sensitivity deficit (p<0.02) and a significant visual acuity deficit (p<0.01) before starting vigabatrin compared with infants with normal vision. Of the 8 infants tested after 5 months on vigabatrin, 6 were compared with their previous baseline results and a significant reduction in peak contrast sensitivity is seen (p<0.03). A slight reduction in peak contrast sensitivity is seen in historical data of children showing signs of toxicity, when compared with baseline results. Conclusions: Reduced baseline peak CS may reflect a susceptibility for impairment of the visual system in children with IS or a delay in their visual development. After 5 months, a further decrease is seen in peak CS is seen, suggesting a vigabatrin-attributed visual deficit. Contrast sensitivity may be used as a potential marker for detecting visual toxicity in infants.

Keywords: drug toxicity/drug effects • electrophysiology: clinical • neuro-ophthalmology: cortical function/rehabil