A multicenter prospective study demonstrated that 63% of test patients responded to the initial procedure. After implantation, 47% of patients became completely dry, and 77% were successful in eliminating “heavy” leakage episodes. Despite substantial success in nearly 80% of patients who received implants, 30% of patients required further surgical revision because of pain or other complications at the generator or implant site. No permanent injuries or nerve damage was reported in the initial trials (121,122).
In a group of 96 patients with implants (who responded favorably during the test stimulation period), reductions in urge incontinence episodes and severity were still seen at an average of 31 months after implantation. The device was removed in 11 of the 96 patients because of lack of efficacy, pain, or bowel dysfunction. There were no permanent injuries (123). The technique for this procedure evolved to include the location of a generation implant site on the back and the performance of the procedure in two stages with initial percutaneous implantation of a quadpolar instead of a unipolar stimulator. These modifications may improve success rates and decrease the morbidity associated with these procedures. A recent systematic review evaluating eight randomized trials concluded that continuous sacral neural stimulation offers benefits for carefully selected patients with overactive bladder and urinary retention in the absence of obstruction, but many implants did not work or required revisions. The review recommended trials to assess effectiveness directly compared to other treatment options (124).
Percutaneous tibial nerve stimulation (PTNS) was first described in 1987 to treat lower urinary tract symptoms and FDA approved in 2000 for overactive bladder. This therapy uses peripheral neurostimulation technique with small (34-gauge) needle electrode inserted at a 60-degree angle approximately 5 cm cephalad to the medial malleolus and slightly posterior to the tibia. The treatment course typically consists of a weekly 30-minute session for 12 weeks. A multicenter, double-blind, randomized control trial involved 220 women with overactive bladder symptoms randomized 1:1 to 12 weeks of treatment with weekly PTNS or sham therapy. The PTNS treatment group achieved statistically significant improvement in bladder symptoms, with 55% reporting moderate to marked improvement compared to 21% in the sham arm compared to baseline (125). The OrBIT (Overactive Bladder Innovative Therapy) trial compared PTNS to extended-release tolterodine in the treatment of OAB and found similar improvements in both groups (126). A large portion of responders in this trial (96%) had sustained improvement in OAB symptoms at 12-month follow-up when receiving periodic treatments (127,128). PTNS may represent a viable treatment option for patients who cannot tolerate side effects from anticholinergic medications, who do not responded to behavioral therapy, or who decline implantable neurostimulators.