Study design, materials and methods
A retrospective review of our prospectively acquired database was conducted for all patients having SNM for OAB and VD in our centre in 2013. All patients had Advanced (tined lead) evaluation, we excluded all patients having basic (Percutaneous Nerve Evaluation - PNE) evaluation. Of the 87 patients having first stage tined lead implantation (FSTLT) 52 (60%) progressed to second stage permanent SNM implant after having achieved an over 50% improvement in their symptoms based on objective (Frequency Volume chart, ICIQ0-OAB and EQ5D Patient Reported Outcome Measures questionnaires) and subjective (patients perceived improvement in symptom control) measures. Data reviewed was on patient and disease demographics, 5 year SNM outcomes, need for revision of SNM or change to alternative therapy and complications.
Interpretation of results
At 5 years from their initial SNM implantation SNM continued to provide effective treatment for OAB and VD in 69% (35) of patients
The system and management of it, isn’t seamless, in that we identified half of the patients who underwent permanent conversion to SNM required reprogramming and subsequent revision of the tined lead in order to try to achieve symptom control. This wasn’t always effective, and in half of those who had return of symptoms the reprogramming pathway and revision of lead proved to be a failure. Those in whom it was effective to revise the lead did need to commit to a reprogramming pathway. This requires multiple hospital visits to input new configurations onto their patient programmer and required a period of evaluation to assess efficacy, both on the original lead, and then on the new revised lead. This is labour intensive for both the clinician and the patient and requires commitment on both parts. It is however effective, if the patient concords with reprogramming and, or, revision at regaining symptom control. Correct surgical placement of the IPG is important to ensure comfort, and pre operative siting can help placement, incorporating patient choice. We found repositioning to be effective in achieving patient satisfaction.
With innovation improving SNM systems, we anticipate MRI compatibility to be a non issue in the future, and as the body of literature grows, SNM in pregnancy will guide symptom control through this period. In summary SNM is effective in the long term, but at the expense of revision/removal surgery in 83% (43).