A new minimally invasive procedure for pudendal nerve stimulation to treat neurogenic bladder: Description of the method and preliminary data

Aims: Pudendal nerve stimulation has beneficial effects on numerous pelvic floor function impairments such as urinary and/or fecal incontinence, retention, and constipation. In preceding literature the implant technique required a fairly complex and invasive surgery, although recent advances with percutaneous placement of the lead through an introducer have made the procedure much less invasive. We performed staged procedure similar to that of sacral neuromodulation (SNM) to place tined lead near the pudendal nerve, using neurophysiological guidance that allowed accurate pudendal nerve stimulation through either perineal or posterior approach. We have named this approach chronic pudendal nerve stimulation (CPNS). Methods: Fifteen neurogenic patients (eight male, seven female) with symptoms of urge incontinence due to neurogenic overactive bladder underwent CPNS. All patients had complete neurophysiological and urodynamic evaluation at baseline and follow-up and were asked to complete voiding and bowel diary for 7 days. Results: During screening, average number of incontinent episodes per day decreased from 7 ± 3.3 to 2.6 ± 3.3 (P <0.02, paired t-test). Eight patients became continent, two improved by more than 88% (from 9 to 1 daily incontinence episode) and two patients reduced the number of incontinence episodes by 50%. The implantable pulse generator (IPG) was subsequently implanted in those 12 patients. Three patients without improvement did not continue to second stage. In implanted patients with 6 months follow-up, urodynamic evaluation showed an objective improvement in the maximum cystometric capacity which increased from 153.3 ± 49.9 to 331.4 ± 110.7 ml (P <0.01, paired t-test). The maximum pressure decreased from 66 ± 24.3 to 36.8 ± 35.9 cmH₂O (P = 0.059, paired t-test). Eight patients reported significant improvement in bowel function. Conclusion: Chronic pundedal nerve stimulation is feasible. Neurophysiological guidance is mandatory to place the lead near the pudendal nerve either using perineal or posterior approach. Further studies must be carried out to identify the best stimulation parameters and to verify the long term results.