Number of active electrodes at time of staged tined lead interstim implant does not impact clinical outcomes.

Objectives: To determine: (1) if obtaining motor response on <4 tined lead electrodes at time of placement affects subjective and objective clinical outcome and (2) voltage requirements to elicit motor response at implant and first postoperative visit number based on number of responding electrodes.

Methods: We reviewed our prospective neuromodulation database to identify patients with unilateral S3 lead placement and motor response (bellows ± toe flexion) on stimulation of 1-4 electrodes, then grouped by number of active electrodes at lead placement. Stage 1 success, reoperation and reprogramming rates, mean voltage at implant and first postoperative visit, and Interstitial Cystitis Symptom/Problem Indices (ICSI-PI) were analyzed using Pearson's Chi-square, Fisher's exact, Kruskal-Wallis or Wilcoxon rank tests.

Results: Two hundred forty four patients met inclusion criteria, categorized into 1-2 (n = 25), 3 (n = 48), and 4 active electrodes (n = 171). There were no significant differences between groups in terms of age, indications for neuromodulation, or stage 1 success. At implant, patients with <4 active electrodes required higher mean voltages for motor responses (5.9, 4.9, and 3.9 volts for each group respectively; P < 0.0001). Mean voltages for sensory threshold at first postoperative programming were 1.5 ± 1.5, 0.9 ± 1.0, and 0.8 ± 1.0, respectively (P = 0.08). Overall reoperation rates, and reprogramming sessions at 24 months did not differ (P = 0.72 and P = 0.50). ICSI-PI scores improved similarly in all groups.

Conclusions: Motor response on four electrodes is not necessary for successful stage 1 trial. Despite higher voltage requirements in those with <4 active electrodes at implant, this difference was not observed at initial postoperative programming. Neurourol. Urodynam. 35:625-629, 2016. © 2015 Wiley Periodicals, Inc.