The effectiveness of lamotrigine in the treatment of photosensitive epilepsy

Photosensitive epilepsy and associated pattern sensitivity are more prevalent in females and are usually treated with sodium valproate. Sodium valproate has an adverse effect profile, which particularly affects females, including teratogenicity, association with the polycystic ovary syndrome and weight gain. It would be useful therefore if an alternative treatment for photosensitive epilepsy could be found. The principle aim of this study was to investigate the effectiveness of lamotrigine in the treatment of photosensitive epilepsy in adults and children. Patients were either drug-naive, commencing lamotrigine therapy or were transferring from other antiepileptic drugs to lamotrigine (primarily sodium valproate) due to lack of response, adverse effects or desired pregnancy. The photoparoxsymal response in the electroencephalograph was used as the primary measure of photo and pattern sensitivity. In addition the effects of lamotrigine on occipital spikes and normal responses in the EEG to visual stimuli were investigated. Secondary measures also included the resting EEG, seizures, body mass index, menstrual function, mood and cognitive function. The results suggest that in adult patients lamotrigine is efficacious in the treatment of photosensitive epilepsy, although it appears inferior to sodium valproate. Lamotrigine does however have a more favourable adverse effect profile than valproate. The results indicate that lamotrigine therapy is suitable for photosensitive epilepsy in women of childbearing age or in patients experiencing unacceptable adverse effects with valproate therapy. Patients are more likely to respond to lamotrigine treatment if they present with sensitivity to a limited number of frequencies. Lamotrigine does not seem to be as efficacious in the treatment of children, although against it may be considered a second line drug if the child does not respond to or will not tolerate sodium valproate.