EFFECTS OF WITHDRAWAL OF PHENYTOIN ON COGNITIVE AND PSYCHOMOTOR FUNCTIONS IN HOSPITALIZED EPILEPTIC PATIENTS ON POLYTHERAPY

The effects of the withdrawal of phenytoin (PT) on cognitive and psychomotor functions of long-term patients in an epilepsy centre were studied. The patients had been treated for many years (31.1 +/- 10.8 yrs.) with PT in combination with other antiepileptic drugs. The serum concentration of PT was in the lower to middle therapeutic range (6.8 +/- 3.1 mg/1). Only patients in which the efficacy of PT was questionable were included in the study. PT was withdrawn in 17 patients. The PT dose was not changed in 12 patients (control group). Psychological tests were carried out immediately before the withdrawal of PT and about 10 weeks later. Tests were also carried out with the control group at the same time. A significantly improved performance (using a composite score) was noted after the withdrawal of PT. The statistical evaluation of the different tests showed an significant improvement in one test of concentration and two tests of psychomotor function (tapping and pursuit rotor with the dominant hand). There was no significant change in the frequency of seizures.