Left Cervical Vagal Nerve Stimulation Reduces Skin Sympathetic Nerve Activity in Patients with Drug Resistant Epilepsy.

We recently reported that the skin sympathetic nerve activity (SKNA) can be used to estimate the sympathetic tone in humans. In animal models, vagal nerve stimulation (VNS) can damage the stellate ganglion, reduce stellate ganglion nerve activity and suppress cardiac arrhythmia. Whether or not VNS can suppress sympathetic tone in humans remain unclear.To test the hypothesis that VNS suppresses SKNA in patients with drug resistant epilepsy.We used electrocardiogram (ECG) patch electrodes to continuously record SKNA in 26 patients with drug resistant epilepsy who were admitted for video electroencephalographic monitoring. Among them, 6 (2 men, age 40±11 years) were previously treated with VNS and 20 (7 men, age 37±8 years) did not. The signals from ECG leads I and II were filtered to detect SKNA.The VNS had an ON-time of 30 s and OFF-time of 158±72 s, with output of 1.92±0.42 mA at 24.17±2.01 Hz. The average SKNA (aSKNA) during VNS OFF-time was 1.06 μV [95% confidence interval, CI, 0.93 to 1.18] in lead I and 1.13 μV [CI, 0.99 to 1.27] in lead II, which was significantly lower than 1.38 μV [CI, 1.01 to 1.75, p=0.036] and 1.38 μV [CI, 0.98 to 1.78, p=0.035] of the control Group, respectively. The heart rate was 65 bpm [CI, 59 to 71] in VNS group, significantly lower than 77 bpm [95% CI, 71 to 83] in control group.Patients with VNS had significantly lower SKNA than patients without VNS.