Retroperitoneal sacral nerve stimulation for the management of chronic pelvic pain after endometriosis treatment

Endometriosis or surgery for it can result in secondary nerve damage and chronic pelvic pain. The results of conservative, surgical treatment and spinal cord stimulation show only a poor outcome. We present a new surgical method of retroperitoneal sacral nerve stimulation for the treatment of neuropathic pelvic pain caused by endometriosis.

Five female patients treated between 2012 and 2017 were retrospectively analyzed. All patients complained of chronic pelvic pain, as well as bladder and bowel dysfunction following several surgeries for endometriosis. These patients underwent laparoscopic re-exploration or re-laparotomy with retroperitoneal implantation of electrodes directly onto the sacral nerve. The intervention was followed by a test period (3-15 days) before the decision for a permanent implantation of a neurostimulator was made. Pain intensity (NRS), generic health status (EQ-5D-5L), Becks Depressions Inventary (BDI-V) and Pain Catastrophizing Scale (PCS) were assessed for the immediate pre- and postoperative status as well as after 3 and 6 months postoperatively. Statistical analysis was performed using Mann-Whitney U and Wilcoxon rank-sum test.

Median age was 40.1 years (IQR25-75 29.4-47.0). Significant improvement of NRS from median 9.0 (IQR25-75 8.5-10.0) preoperatively to 5.0 (IQR25-75 1.75-6.25; p=0.01) at 3 and 2.5 (IQR25-75 0.25-4.5; p=0.01) at 6 months follow-up was achieved. Median EQ-5D-3L index value before treatment was 0.19 (IQR25-75 0.13-0.31) indicating a low quality of life. After 3 and 6 months a significant improvement to 0.73 (IQR25-75 0.71-0.90; p=0.04) and 0.76 (IQR25-75 0.74-0.95; p=0.03) was seen. The preoperative median BDI-V score of 46.0 (IQR25-75 40.5-58.0) indicating a major depressive mood increased significantly improved to 26.0 (IQR25-75 19.0-39.0; p=0.0264) and 12.0 (IQR25-75 4.5-34.0; 0.0271) after 3 and 6 months respectively. Preoperative PCS was highly elevated with a median score of 42.0 (IQR25-75 37.5-50.5). After 3 and 6 months a significant reduction to 18.0 (IQR25-75 8.0-22.5; p=0.0091) and 3.0 (IQR25-75 1.0-10.5; p=0.0088) was seen, respectively. Furthermore, 4 patients had a complete reduction in demand for analgesics.

This unique method is an effective treatment option for chronic, neuropathic pelvic pain after endometriosis treatment. However, this method requires an interdisciplinary surgical team approach.