Contrast sensitivity is reduced in children with infantile spasms.
OBJECTIVE
To investigate whether visual deficits in children with infantile spasm (IS) are the result of seizure activity or of treatment with the anticonvulsant drug vigabatrin (VGB).


METHODS
Vision function was determined in three experiments by determining peak contrast sensitivity (CS) and grating acuity (GA) with the sweep visual evoked potential. Cross-sectional study A: 34 children, including 11 patients with childhood epilepsy with exposure to VGB for at least 6 months, 10 with childhood epilepsy exposed to antiepileptic drugs other than VGB, and 13 normally developing children. Cross-sectional study B: 32 children, including 16 with IS naïve to VGB and 16 normally developing children. Longitudinal study: seven children with IS naïve to VGB, with subsequent follow-up 5 to 10 months after starting VGB.


RESULTS
In cross-sectional study A, the median CS was reduced by 0.5 log units (P = 0.025) in children with epilepsy exposed to VGB compared with those exposed to other antiepileptic drugs and normally developing children. In cross-sectional study B, the median CS was reduced by 0.25 log units (P = 0.0015) in children with IS (VGB naïve) compared with normally developing children. Longitudinal assessment showed no decrease in CS in children with IS who were followed up 5 to 10 months after starting VGB. There was no difference in GA among groups in any of the experiments.


CONCLUSIONS
Patients with IS have CS deficits, but a sparing of GA. This deficit is present before VGB treatment and does not worsen with treatment onset. Results suggest that visual dysfunction is largely the result of the seizures themselves.
Mirabella
Giuseppe
G
Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada.
Morong
Sharon
S
Buncic
J Raymond
JR
Snead
O Carter
OC
Logan
William J
WJ
Weiss
Shelly K
SK
Abdolell
Mohamed
M
Westall
Carol A
CA
D000293:Adolescent; D000927:Anticonvulsants / Q000008:administration & dosage* / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D015350:Contrast Sensitivity / Q000187:drug effects / Q000502:physiology*; D003430:Cross-Sectional Studies; D005074:Evoked Potentials, Visual / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D013036:Spasms, Infantile / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D020888:Vigabatrin / Q000008:administration & dosage* / Q000009:adverse effects; D014786:Vision Disorders / Q000139:chemically induced / Q000453:epidemiology / Q000209:etiology*; D014792:Visual Acuity / Q000187:drug effects / Q000502:physiology
D000927:Anticonvulsants; D020888:Vigabatrin