Validation of a sham for percutaneous tibial nerve stimulation (PTNS).

AIM: Percutaneous tibial nerve stimulation (PTNS) supposedly demonstrates 50-60% improvement in OAB symptoms with no sham-controlled trials reported. This study determined the efficacy of a sham for PTNS.

METHODS: Thirty healthy volunteers (15 women; 15 men) in this blinded pilot study were randomized into two equal groups: one group had PTNS on the right and sham on the left; the other group had PTNS on the left and sham on the right. A drape obscured their lower extremities. The sham utilized a placebo needle placed at the PTNS site along with a transcutaneous electrical nerve stimulator (TENS) pad on the ipsilateral foot. The unit was activated until stimulation was felt. PTNS was performed on the opposite leg, with the grounding pad mimicking the sham pad placement. PTNS stimulation was given until the subject felt stimulation in the foot. Subjects had 1 simultaneous 15 min testing of the PTNS vs. sham. Subjects then completed a questionnaire stating which leg they thought had the sham and PTNS (or "unknown"). The primary endpoint of the study was the ability to accurately identify the sham.

RESULTS: In total, 10/30 (33%) of the shams were identified correctly. We would expect 50% to be identified by guessing, but only 33% were correctly identified. Females identified the sham correctly more often than males (40% vs. 27%). This procedure was validated as a feasible sham for PTNS.

CONCLUSIONS: This is the first validation of a sham for PTNS that may be used in future placebo-controlled research.