Functional magnetic stimulation of the vagus nerve enhances colonic transit time in healthy volunteers

Sacral magnetic stimulation (MS) of the full and empty rectum increases rectal and decreases anal pressures. Rectal evacuation was produced by intermittent MS. MS activates not only the muscles but also the nervous tissue. In the present study I investigated the effect of MS of the vagus nerve on the colonic transit to evaluate the possibility of using this method in the treatment of constipation due to colonic inertia. Forty healthy volunteers were divided into 2 equal groups: study (mean age 46.6 years; 13 men, 7 women) and control (mean age 43.9 years; 13 men, 7 women). MS was produced by a magnetic stimulator and a 2-cm coil placed in the middle of the ventral surface of the neck. MS parameters were set at 70% of maximal intensity, 40 Hz frequency, 10 seconds on, 10 seconds off for 20 minutes and followed by 60 minutes rest. This sequence was performed for 5 cycles. Colonic transit was determined by ingesting 20 radiopaque markers and by radiographing the subject. In the control group, 6 subjects had passed all the markers on the sixth day post-ingestion and all the remaining subjects except two on the seventh day; the last two subjects passed all the markers on the eighth day. In the study group, more than 50% of the subjects had passed all the markers already by the fifth post-ingestion day; the others completed passage of the markers by the sixth day. In the study group 100% of the markers had passed by the sixth post-ingestion day against 30% in the control group. These findings suggest that MS of the vagus nerve enhances colonic transit by augmenting the peristaltic activity of the gut. The procedure might thus be used for the treatment of constipation resulting from delayed colonic transit. Received: 17 May 1999 / Accepted in revised form: 30 July 1999