[Reversible neuropsychological deterioration associated to zonisamide in a paediatric patient with tuberous sclerosis].

Aim: To document reversible cognitive deterioration associated to high doses of zonisamide, using the Reliable Change Index to control practice effects derived from repetitive neuropsychological assessments.

Case Report: A 11 year-old boy with tuberous sclerosis complex and left frontal refractory epilepsy, evaluated within a paediatric epilepsy surgery program. The epileptogenic zone was found to be related with a tuber situated on the left inferior frontal gyrus. The effects of high doses of zonisamide simulate a disturbance of eloquent cortex within the epileptogenic zone and the impact of uncontrolled seizures on cognitive functioning over the language-dominant hemisphere. Drug withdrawal significantly improved total intelligence index, verbal comprehension intellectual index and specific language-sustained cognitive abilities, beyond practice effects.

Conclusions: The differentiation between cognitive effects of drugs and functional deficits resulting from eloquent cortex involvement within the epileptogenic zone can be of crucial importance in the decision-making process for epilepsy surgery.