NO EFFECT OF LONG-TERM VIGABATRIN TREATMENT ON CENTRAL-NERVOUS-SYSTEMCONDUCTION IN PATIENTS WITH REFRACTORY EPILEPSY - RESULTS OF A MULTICENTER STUDY OF SOMATOSENSORY AND VISUAL-EVOKED POTENTIALS

Purpose: In dogs, vigabatrin (VGB) has been associated with intramyeli nic edema producing delayed central conduction in somatosensory and vi sual evoked potentials (SEP, VEP). No such effects have been reported in humans. We assessed whether abnormalities of central conduction cou ld be detected prospectively in patients with epilepsy treated with VG B as long-term add-on medication. Methods: Two hundred one patients wi th refractory partial epilepsy were enrolled and monitored for as long as 2 years. VGB was added to the treatment at an average dose of 2-3g /day. Conduction in somatosensory and visual pathways was assessed by median nerve SEP and pattern VEP recordings performed at inclusion and once every 6 months. The upper limit and test-retest variability of E P latencies were evaluated at time of enrollment in the patient group. Prolonged N13-N20 or P14-N20 SEP intervals and P100 VEP latency >2.5 SD above the baseline mean, observed on repeated runs in the same sess ion and exceeding the test-retest variability at enrollment were consi dered to indicate central conduction slowing. Results: One hundred nin e patients completed the 2-year study period, and 92 discontinued VGB, of whom 37 were monitored with regard to EP until the end of the stud y. No consistent change in SEP or VEP was observed in the entire group during VGB treatment. The number of occasional EP values outside the baseline range in patients treated with VGB similar to that in patient s whose VGB treatment had been discontinued. Conclusions: We detected no evidence of changes in SEP and VEP attributable to altered neuronal conduction in the CNS during long-term VGB treatment.