No evidence for cognitive side effects after 6 months of vagus nerve stimulation in epilepsy patients

Vagus nerve stimulation (VNS) can reduce seizure frequency in epilepsy patients and may affect central mechanisms of brain functioning. Experimental studies have provided evidence of cognitive alterations during VNS on phases. This single-arm follow-up study evaluates the potential of VNS to affect cognitive performance following long-term treatment. Thirty-six adult patients with medication-resistant epilepsies enrolled. Cognition was assessed before and at least 6 months after implantation of the stimulation device by a comprehensive neuropsychological assessment battery comprising tests on attention, motor functioning, short-term memory, learning and memory, and executive functions. Neither multiple testing of single score changes nor multivariate testing of cognitive domains revealed significant pre-post changes. Improvements in attentional performance were completely explained by practice effects as is usually expected. In particular, no negative side effects were revealed. These findings are in line with the clinical impression that VNS does not affect cognitive performance.