Chronic sacral nerve stimulation as a novel treatment for stress urinary incontinence-A rat model

We propose an animal model to evaluate the effect of chronic sacral nerve stimulation (SNS) on surgically induced intrinsic sphincter deficiency (ISD) secondary to transabdominal urethrolysis (U-Lys).

Twenty-five 6-week old virgin female Sprague-Dawley rats were divided into four groups: control (CTRL), U-Lys only, SNS only, and both (U-Lys/SNS). Groups CTRL (N = 5) and U-Lys only (N = 5) were maintained in the animal research facility in standard fashion for 2 weeks. Groups SNS only (N = 5) and U-Lys/SNS (N = 10) underwent chronic SNS for 6 continuous hours daily for 2 weeks. Retrograde leak point pressure (RLPP) was measured at baseline and at 2 weeks following observation or treatment. Five consecutive RLPP measurements were averaged per measurement cycle. SAS 9.3 was used to evaluate means and standard deviation.

Baseline mean RLPP was 65 mmHg. The U-Lys only group mean RLPP at initial urethrolysis (58 mmHg) decreased (31 mmHg, P < 0.0001) after 2 weeks of observation. In the SNS only group, mean RLPP significantly increased from baseline (73 mmHg) after 2 weeks of chronic SNS stimulation (80 mmHg, P < 0.01). In rats that underwent both U-Lys and SNS stimulation mean RLPP was initially low (46 mmHg) after U-Lys and then significantly increased after 2 weeks of SNS (65 mmHg, P < 0.0001).

Chronic SNS mediates an improvement in urethral sphincteric function at stimulation parameters similar to those used in humans for treating voiding dysfunction. SNS increased urethral resistance in rats with and without surgically induced ISD.