A short-term analysis of parameters affecting the outcome of sacral neuromodulation

Purpose: Sacral neuromodulation has become an effective option for controlling intractable symptoms of overactive bladder: urgency and urge incontinence. However, it has its limitations in that an intermittent pulse generator (IPG) is insertable only in patients with symptom improvement of at least 50%. In this study, we aimed to investigate the parameters that predict surgical outcomes. Materials and Methods: Data from 31 candidates for sacral neuromodulation were retrospectively analyzed. Twenty patients out of 31 candidates had satisfactory symptom improvement after tinned lead test implantation, which resulted in IPG implantation. Data and neural stimulation parameters were compared and analyzed between successful IPG implants (group 1) and test failures (group 2). Results: The percentage of female patients was higher in the IPG implant group (group 1: 95%, group 2: 64%). There was a significant difference in symptom duration, between the two groups (group 1: 40.5 months, group 2: 91 months). There was a significant difference in the number of episodes of urgency between the two groups (group 1: 6.83/day, group 2: 9.66/day, p=0.012), and severity of urgency showed significant difference between two groups (group 1 < group 2, p=0.027). Conclusions: In females, the severity and duration of symptoms may be factors predicting poor response to neuromodulation. Although there is a need for further data analysis, this study suggests that the proper selection of surgical time is important in controlling patients' lower urinary tract symptoms by neuromodulation.