Effect of vagal nerve stimulation on auditory and visual event-related potentials.
Chronic unilateral vagal nerve stimulation (VNS) has been recently introduced into the therapy for intractable epileptic seizures. Its effect on cognitive functions in VNS-treated patients remains controversial. The aim of the present study was to evaluate the possible impact of therapeutic VNS on cognitive functions by means of event-related potentials analysis. Ten patients with medically intractable epilepsy, who had been implanted with VNS devices, participated in the study. Auditory and visual event-related potentials (ERPs) were repeatedly recorded, first just before the implantation of VNS devices, and then again 3-6 months after the device activation. The effect of lower intensity stimulation on the P3 component of ERPs was assessed. No significant differences were found in auditory ERPs; the latencies of P3 as well as N2/P3 peak-to-peak amplitudes were virtually identical. The same was true for mean P3 latencies of visual ERPs. However, higher visual N2/P3 peak-to-peak amplitudes were observed in the responses to targets that followed VNS, with a significant finding at the electrodes investigated. When comparing the effect of VNS on visual N2/P3 amplitude in each electrode separately, the most expressive differences were found in the frontal region. This observation supports the theory of a possible positive effect of low-intensity VNS on the cognitive functions.
Brázdil
M
M
Department of Neurology, Epilepsy Center Brno, Masaryk University, St Anne's Hospital, Brno, Czech Republic. mbrazd@med.muni.cz
Chadim
P
P
Daniel
P
P
Kuba
R
R
Rektor
I
I
Novák
Z
Z
Chrastina
J
J
D000328:Adult; D004599:Electric Stimulation Therapy; D004569:Electroencephalography / Q000187:drug effects; D004827:Epilepsy / Q000503:physiopathology* / Q000628:therapy*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology*