A new minimally invasive technique for pudendal nerve stimulation.

AIM

Pudendal nerve stimulation (PNS), which is an alternative to sacral nerve stimulation, requires neurophysiological confirmation of correct siting of the electrode. We describe a modification of the existing technique where placement is assisted by guidance to the ischial spine by a finger introduced per anum.

METHOD

Cadaveric dissection was carried out to confirm the accuracy of this new approach. The surface marking of the ischial spine is marked. A stimulating needle electrode inserted through a skin incision at this point, is advanced towards the ischial spine using a finger introduced per anum as a guide. Once effective stimulation of the pudendal nerve is confirmed by observed and palpated contraction of the anal musculature, a permanent stimulating electrode is inserted and the position confirmed by radiological screening.

RESULTS

Using cadaveric studies, the correct surface markings for needle placement were confirmed. This technique was then applied successfully for in vivo insertion of the needle electrode in 20 patients with bowel dysfunction, with only one lead displacement occurring over a mean follow-up period of 12 months.

CONCLUSION

Finger-guided assistance of PNS electrode insertion is simple and reproducible without requiring neurophysiological confirmation of nerve stimulation to ensure correct lead location.