Value of Two-Stage Sacral Nerve Stimulation for Voiding Disorders
Dr. Paul D. M. Pettit
Mayo Clinic
Jacksonville, Florida

Objective:  Sacral nerve stimulation is an exciting new therapy for refractory urge frequency, urge incontinence, and nonobstructive urinary retention.  The current approach to sacral nerve stimulation is a two-phase procedure.  The first is a test stimulation (percutaneous nerve evaluation) of four to seven days.  If successful, then the second phase is an implantation of quadrapolar lead and implanted programmable generator.  Only 52% of patients go from test stimulation to implantation.  Another issue is 20% of patients receiving the implant have a lesser response than the test stimulation.  The two-stage implant is evaluated to eliminate this high technical failure rate and subset of patients. 
Methods:   The two-staged implant is carried out by one of two techniques.  The first technique, the quadrapolar lead, is secured to the periosteum.  The second technique, the quadrapolar lead is secured to the thoracolumbar fasia.  In both techniques, the quadrapolar lead is connected to a percutaneous extension lead which is brought out the contralateral side.  The second stage is the same for both techniques.  Involving explantation of the percutaneous extension lead and implantation of a 10 cm extension lead and implanted programmable generator. 
Results:   Retrospective data was collected from five physicians using the staged approach, two US physicians and three European.  Ninety-four patients were identified of which 80 responded to the medical release form and permission form.  Of the 80 patients, there were 14 males (17.5 %) and 66 females (82.5%).  The average age was 52 (19-85).  The average screening time (first stage) was 14.7 ± 8.8 days (3-41).  Seventy-six patients (95%) were reported to have successful screen (first stage).  Twenty-four of the 80 patients had undergone unsuccessful test stimulations.  Sixteen (87.5%) of these patients had successful first-stage screens.  Adverse events occurring included pain in 18 patients (22.5%), infection in 4 patients (5%), device problems in 25 patients (31.3%), elimination problems in 4 patients (5%), and miscellaneous in 10 patients (12.5%).
Conclusion:   The two-stage procedure of sacral nerve stimulation improves the likelihood of success to 91% and eliminates the 20% decrease in effectiveness when changing from test stimulation lead to the implantation lead.