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Pudendal Neuromodulation

Pudendal neuromodulation places a stimulating lead at the pudendal nerve, usually near Alcock's canal or the ischial spine, rather than at the S3 sacral root used by sacral neuromodulation (SNM).[1] It is investigational for lower urinary tract indications and is not an established alternative to SNM; most published experience is small, uncontrolled, and concentrated in pudendal neuralgia rather than in overactive bladder, retention, or underactive bladder.[1][2]

For the family-level comparison with SNM, percutaneous tibial nerve stimulation, and implantable tibial systems, including the short-term randomized crossover trial of pudendal versus sacral stimulation for voiding dysfunction, see Neuromodulation. That trial's denominators and results are not repeated here.[3]

Rationale and Target​

The pudendal nerve carries somatic afferent and efferent fibers from the external urethral and anal sphincters, perineal skin, and genitalia, and contributes to bladder, bowel, and pelvic-floor reflex circuits at a different level than the S3 sacral root used by SNM. Stimulating it has been proposed both for voiding-phase lower urinary tract dysfunction and, more often in reported series, for chronic pudendal-territory pain.[1][4]

Lead Placement​

Reported techniques place a lead near the ischial spine or within Alcock's canal under fluoroscopic or anatomic-landmark guidance, usually prone with sedation and local anesthetic. One described approach uses perirectal electromyography and test stimulation at approximately 5 mA and 5 Hz, confirming proximity to the nerve by an anal "wink" response or compound muscle action potential before placing a long quadripolar lead; intraoperative test stimulation with manual pressure simulating sitting and lying has also been described to check for positional capture loss. This is the operative sequence as the chapter authors describe it, not a standardized protocol.[1] A separate anatomic-landmark technique ("STAR," using the ischial spine, ischial tuberosity, acetabulum, and anal rim) was developed in cadavers and tested in a 20-patient pilot to make lead placement more reproducible; in that series, pain decreased significantly only with bilateral stimulation, and mean bilateral operative time was about 85 minutes with a mean of 3.5 puncture attempts per side to reach the nerve.[5]

FDA Status and Current Evidence​

Pudendal neuromodulation has no FDA-approved indication for overactive bladder, retention, pelvic-floor dysfunction, or underactive bladder.[1] Evidence for voiding-dysfunction indications is limited to a small short-term randomized crossover trial against sacral stimulation (see Neuromodulation) and animal models; no human trial for underactive bladder is reported.[1][3]

Most clinical experience is in refractory pudendal neuralgia, where it is used off-label after pharmacologic therapy, pelvic-floor physical therapy, and nerve blocks have failed:

SeriesPopulationReported outcome
Hoang Roberts 2021[6]13 patients with pudendal neuralgia, wireless pudendal lead (StimWave), retrospective feasibility study10/13 (76.9%) had >50% pain improvement after the trial period and 6/13 (46.1%) reported 100% improvement; 9 underwent permanent implantation, and 5/9 reported >50% pain improvement at last postoperative visit. Complications at follow-up included lead migration (2), a broken wire (1), and a nonfunctioning antenna (2)
Peters 2015[7]19 patients with pudendal neuralgia and a tined lead already placed at the pudendal nerve, retrospective chart review plus mailed surveyPain relief after lead placement was complete in 3, almost complete in 3, significant in 10, and small in 3; all 19 had a permanent generator placed, and 5 were later explanted at a mean of 2.95 years

These are small, uncontrolled, single- or few-center reports without a comparator arm; they describe a selected refractory-pain population and do not establish an expected response rate for a general audience, a durability estimate beyond the reported follow-up, or a role in OAB, retention, or underactive bladder.[6][7]

Complications​

Reported hardware problems include lead migration, lead or wire fracture, and loss of signal from a malfunctioning antenna in wireless systems; aberrant stimulation of a nearby nerve territory and local insertion-site discomfort have also been described.[6] No series in this literature reports a systematic, procedure-specific complication rate large enough to generalize.

Practical Framing​

Pudendal neuromodulation should be presented to patients as a research-level, off-label option, not as an established alternative to SNM, PTNS, or implantable tibial neuromodulation for urinary indications, and not as a standard treatment for refractory pudendal neuralgia outside a program experienced with the technique. Counsel on the limited, small, uncontrolled evidence base before considering it, and reserve it for patients who have exhausted conservative, pharmacologic, and injection-based pudendal neuralgia therapy.[1][6][7]

See Also​

References​

1. Hoang Roberts L, Vollstedt A, Gilleran J, Peters KM. Bladder dysfunction and pelvic pain: the role of sacral, tibial, and pudendal neuromodulation. In: Martins FE, Holm HV, Sandhu JS, McCammon KA, eds. Female Genitourinary and Pelvic Floor Reconstruction. Springer; 2023:255-274.

2. Peters KM. Pudendal neuromodulation for sexual dysfunction. J Sex Med. 2013;10(4):908-911. doi:10.1111/jsm.12138

3. Peters KM, Feber KM, Bennett RC. Sacral versus pudendal nerve stimulation for voiding dysfunction: a prospective, single-blinded, randomized, crossover trial. Neurourol Urodyn. 2005;24(7):643-647. doi:10.1002/nau.20174

4. Spinelli M, Malaguti S, Giardiello G, Lazzeri M, Tarantola J, Van Den Hombergh U. A new minimally invasive procedure for pudendal nerve stimulation to treat neurogenic bladder: description of the method and preliminary data. Neurourol Urodyn. 2005;24(4):305-309. doi:10.1002/nau.20118

5. Heinze K, Hoermann R, Fritsch H, Dermietzel R, van Ophoven A. Comparative pilot study of implantation techniques for pudendal neuromodulation: technical and clinical outcome in first 20 patients with chronic pelvic pain. World J Urol. 2015;33(2):289-294. doi:10.1007/s00345-014-1304-7

6. Hoang Roberts L, Vollstedt A, Volin J, McCartney T, Peters KM. Initial experience using a novel nerve stimulator for the management of pudendal neuralgia. Neurourol Urodyn. 2021;40(6):1670-1677. doi:10.1002/nau.24735

7. Peters KM, Killinger KA, Jaeger C, Chen C. Pilot study exploring chronic pudendal neuromodulation as a treatment option for pain associated with pudendal neuralgia. Low Urin Tract Symptoms. 2015;7(3):138-142. doi:10.1111/luts.12066