• electric nerve stimulation;
  • LUTS;
  • minimally invasive


To describe patient selection for sacral neuromodulation, also known as Interstim therapy, and the results of tined-lead implantation in the medium term.


In all, 49 patients, 39 with refractory overactive bladder symptoms and 10 with urinary retention, were implanted with the tined lead under local anaesthesia. The mean (sd) test period was 12.4 (5.8) days. Patients were implanted when they had a ≥ 50% improvement in voiding diary variables during the test period. The mean follow-up for implanted patients was 15.5 (7.9) months. Changes in voiding variables were compared using a t-test.


Ten patients had a one-stage and 39 a two-stage implant; of the latter group, 31 (80%) had a positive response and eight (21%) did not. In all, 31 patients were included in the follow-up. At the last follow-up, 28 (90%) patients had a >50% improvement in diary variables and three (10%) did not. In 21 patients with urgency symptoms the mean (sd) number of voids decreased from 11.7 (8.9)/day at baseline to 7.3 (3.4)/day (P = 0.1); the voided volume increased from 160.2 (70.7) mL to 231.1 (119.5) mL (P = 0.001); and the number of leakages decreased from 9.5 (8.7) to 3.3 (2.2)/day (P = 0.17). In the 10 patients with retention, the number of catheterizations decreased from 5.44 (1.6)/day with a volume of 297.6 (76.8) mL, to 1.2 (1.7)/day and 111.6 (158.1) mL; the mean number of voids increased from 3.7 (3.8)/day with a volume of 123.3 (141.7) mL, to 4.2 (2.4)/day and 248.3 (146.0)mL. There were no significant differences in the variables in the patients with retention. Seven patients had an adverse event. There was one incomplete electrode migration that was treated conservatively.


This new minimally invasive approach gives positive results in the medium term. Two-stage testing with the tined lead seems more reliable than the classic percutaneous nerve evaluation. The lead anchoring method seems sufficient for fixing the electrode in the medium term.