WITHDRAWAL OF ANTIEPILEPTIC MEDICATION IN CHILDREN - CORRELATION OF COGNITIVE FUNCTION AND PLASMA-CONCENTRATION - THE MULTICENTER HOLMFRID STUDY

Eighty-three patients with epilepsy and 83 matched controls completed 12 computerized cognitive tests while on antiepileptic drugs and six m onths later when they had been medication-free for three to four month s. All patients had been seizure-free for more than one year and were on monotherapy with carbamazepine (CBZ, n = 56), valproate (VPA, n = 1 7), or phenytoin (PHT, n = 10). The tests and plasma concentration col lection were done at noon. The mean peak plasma concentrations in the CBZ patients were as follows: 31% below 30 mu mol/l, 48% between 30 an d 42 mu mol/l and 21% above 42 mu mol/l. No difference in performance could be detected between the groups. One significant correlation betw een plasma concentration and test results was found. The mean VPA conc entration was 625 mu mol/l (S.D. 189). A tendency towards a weak negat ive correlation between test results and plasma concentration was pres ent. The PHT patients' therapeutic range had a mean concentration of 3 2.0 mu mol/l (S.D. 18.5). One significant correlation between a memory test and plasma concentration could be detected. Overall, the patient s in the different antiepileptic groups performed less good than the c ontrol group and in a few cases the differences were statistically sig nificant when compared either before or after withdrawal. A comparison of the changes after withdrawal showed improvement in the majority of tests, but these changes were also present in the matched control gro up.