Abstracts

Rationale: Background: Vigabatrin, a structural analogue of the inhibitory neurotransmitter GABA, is widely used as initial monotherapy in patients with infantile spasms and as add on therapy in patients with partial onset seizures. Vigabatrin is associated with retinal toxicity causing constriction of the visual field. Objective: To assess what effect add-on AED therapy has on the incidence of retinal toxicity in patients being treated with vigabatrin. Methods: Single centre retrospective study of patients treated with vigabatrin at our centre from Jan 1999 until Dec 2009. Medications received, the dosages and duration of treatment were examined and correlated with ERG results. Results: ERG results were recorded for 247 patients included in the Ophthalmology database during this 10 year period. Adequate data to allow for definition of toxicity was obtained for 160 patients. Toxicity was detected in 18 of these 160 patients (11.25%). 14 (77%) were in the group treated with additional AEDs, the other 4 received VGB as monotherapy Conclusions: The prevalence of toxicity detected by ERG was 11.25% among 160 patients assessed adequately. We detected a significantly higher percentage of toxicity in the group of patients treated with VGB and additional AEDs (p=0.018). Our numbers were not sufficient to detect which AED or combination of AEDs which might be associated with higher risk.