Association Between Stimulation Parameters and Loss of Efficacy of Selective Sacral Nerve Root Stimulation

Objectives:  This study sought to determine the association between stimulation parameters at the time of implantation and loss of efficacy on long-term follow-up. Material and Methods:  Between 2002 and 2007, 143 patients underwent selective sacral nerve root stimulation at our center as a treatment for voiding dysfunction. Nine patients were explanted because of loss of efficacy. The patients' charts were retrospectively reviewed and compared with those of a well-matched group of 12 positive responders. A t-test was used to determine the differences in voiding parameters and stimulation parameters between both groups (at p < 0.05). Results:  The baseline amplitude levels in the loss of efficacy group were significantly higher than those of the control group (2.08 ± 0.35 V vs. 1.27 ± 0.25 V) (p= 0.008). The impedance levels were significantly higher in the loss of efficacy group than the control (1032.4 ± 181 Ω vs. 590 ± 44.6 Ω) (p= 0.025). Conclusion:  High stimulation parameters at the time of implantation were associated with loss of efficacy at the long-term follow-up.