[Effects of topiramate in patients with epilepsy and intellectual deficits]

There is little knowledge about the effects of topiramate in intellectually impaired epileptic patients. This open prospective study compares seizure frequencies during a 3-month period of topiramate add-on therapy (after 3 months of titration) compared with a 3-month baseline period. An intention-to-treat analysis was made on the first 24 consecutive topiramate-treated adult patients (residents of the Bethel epilepsy centre, therapy-resistant epilepsy, intellectual impairment of different degrees, one half with neurological deficits). The responder rate (at least a 50% reduction in seizure frequency) was 37.5%. One patient became completely seizure-free during post-evaluation (up to 24 months). Efficacy was not different between different epileptic syndromes or seizure types (case number too small). Responders had topiramate dosages above 200 mg/day and serum concentrations above 2.2 micrograms/ml. Six patients (25%) experienced serious neuropsychiatric complications such as confusion and severe deceleration of thinking and acting, up to complete helplessness (at topiramate dosages from 50 mg/day to 900 mg/day and serum concentrations from 2.2 micrograms/ml to 8.0 micrograms/ml). Preexisting brain damage may enhance the risk of unwanted central nervous effects.