Effect of Childhood Epilepsy and Antiepileptic Drugs on Visual Evoked Potential Response and Optical Coherence Tomography

Background : Epileptic seizures arise from an excessively synchronous and sustained discharge of a group of neurons. The single feature of all epileptic syndromes is a persistent increase of neuronal excitability. Visual affection in epileptic children could be attributed to the disease itself or the use of anti-epileptic drugs, these changes may involve abnormal electro-physiological response. This biphasic study, conducted at the neuro-pediatric clinic at neurology department at Ain Shams University, aimed to investigate effect of idiopathic childhood epilepsy per se on (1) visual evoked potential and (2) optical coherence tomography and effect of selected two antiepileptic medications on them. All subjects were exposed to visual evoked potential and only cooperative subjects exposed to ocular coherence tomography before and after anti-epileptic drugs and were followed up over 2 years. Results : The study included 50 newly diagnosed epileptic children and 50 healthy controls, the mean P100 latency in the right eyes of the control group was 110.4 ± 3.76ms, while in the patients group was 114.94 ± 12.81ms that showed significant difference between the two groups with p-value (0.020). After 2 years of treatment by levetiracetam and valproate, the mean P100 latency of the right and left eyes in the valproate group was 112.34 ± 7.05 and 112.59 ± 5.2ms respectively and it was 114.85 ± 10.39ms and 116.14 ± 9.84ms respectively in the valproate group, which showed insignificant difference between the two groups. The mean average of retinal nerve fiber layer thickness between patients and controls were significant in both right and left eyes with p- value 0.002 and < 0.001 respectively. After 1 year of treatment by levetiracetam in the 1st group and valproate in the 2nd group, there was no significant difference between the 2 groups neither regarding retinal nerve fiber layer thickness nor ganglion cell complex in both eyes. Conclusion : There was prolonged latency in the epileptic children before starting anti-epileptic drugs more than the control group; also there was thinning of the retinal nerve fiber layer thickness and average part of the ganglion cell complex thickness more in the epileptic children than in the healthy controls.