Efficacy and safety of topiramate in refractory epilepsy of childhood. Long-term follow-up study

This study aimed to evaluate the long-term efficacy and safety of topiramate in treating children with drug-resistant epilepsy. A multicentric, retrospective, open-label, add-on study was under-taken of 277 children (mean age 8.4 years; range 12 months to 16 years) affected by drug-resistant epilepsy. The efficacy was rated according to the seizure types and epilepsy syndrome. After a mean period of 27.5 months of treatment (range 24-61 months), 11 patients (40/6) were seizure free and 56 (20%) had more than 50% reduction in seizure frequency. The efficacy of topiramate treatment was noted in localization-related epilepsy and in generalized epilepsy. In addition, in a group of 114 patients, we compared the initial efficacy (evaluated after a mean of 9 months of follow-up) and the retention at a mean of 30 months of topiramate with regard to loss of efficacy (defined as the return to the baseline seizure frequency). Fifty-five (48%) of 114 patients were initial responders. The retention at a mean of 30 months was 23 of 114 patients (20%), 4 of whom (3.5%) were still seizure free. A loss of efficacy occurred in 32 of the 55 initial responders (58%). It was prominent in patients with generalized epilepsy, such as symptomatic infantile spasms and Lennox-Gastaut syndrome, as well as in those with Dravet syndrome. By contrast, a well-sustained topiramate efficacy was noted among patients with localization-related epilepsy. Globally, adverse events were observed in 161 patients (58%) and were mainly represented by weight loss, hyperthermia, sedation, and nervousness, which, in most cases, disappeared after slowing titration or reducing the dosage of the drug. In conclusion, the present long-term study confirms that topiramate represents a useful drug effective in a wide range of seizures and epilepsy syndromes. Moreover, preliminary data seem to suggest that the efficacy of topiramate, when evaluated in the long-term perspective, is more sustained in localization-related epilepsy than in generalized epilepsy.