[The effect of chronic Vagus Nerve Stimulation (VNS) on the central conduction time assessed by multimodal evoked potentials in patients with drug resistant epilepsy: preliminary report].

: Changes over time in evoked potentials of various modality (VEP, SSEP and BAEP) were analyzed in 3 patients, submitted to chronic Vagus Nerve Stimulation (VNS) due to drug resistant epilepsy. The aim of a study was to establish which cerebral structures are most prone to change their baseline electrophysiological status in consequence of chronic VNS. Evoked potentials were examined before the Vagus Nerve Stimulator implantation and at arbitrarily defined follow-ups several months after the implantation. Preliminary results obtained in a small group of 3 patients suggest a possible prolongation of the central conduction time in the examined modalities of evoked potentials due to the VNS treatment. A hypothetical mechanism of antiepileptic VNS action might be related to the permanent stimulation of brainstem and cortical structures that limit seizures propagation through hyperpolarisation both at the cortical level and in subcortical structures.