[Therapeutic effects of sacral neuromodulation on detrusor underactivity]

To evaluate the effects of sacral neuromodulation (SNM) on detrusor underactivity (DUA).

From December 2019 to April 2020, 6 patients with DUA who had been treated with SNM were assessed retrospectively. The average age was 58 years (46-65 years), with 3 males and 3 females. All the patients were diagnosed with DUA by urodynamics examination. Obstruction of bladder outlet was excluded through the cystoscopy. No patient had the history of neurological disease. All the patients were placed with the bladder colostomy tube before SNM. One female patient accepted the trans-urethral resection of bladder neck. Two male patients accepted the trans-urethral resection of prostate. All the 3 patients had no improvement of void symptom after the urethral operation. Before SNM, the average 24 h times of voiding was 23.8 (18-33), average volume of every voiding was 34.2 mL (10-50 mL), average residual volume was 421.7 mL (350-520 mL). The preoperative and postoperative 24 h urine frequency, average voided volume, and average residual urine volume were compared respectively.

Totally 6 patients underwent SNM with stage Ⅰ procedure. The operation time for stage Ⅰ procedure was 62-135 min (average 90 min). After an average follow-up of two weeks, stage Ⅱ procedure was performed on responders. Four patients accepted stage Ⅱ procedure (conversion rate 66.7%), the other two patients refused the stage Ⅱ procedure because the urine frequency did not reach the satisfied level. But all the patients had the improvement of residual urine volume. For the 4 patients at the follow-up of 10-15 months, the improvement of void was still obvious. For the all patients after stage Ⅰ procedure, the average 24 h urine frequency reduced to 13.5 times (9-18 times, P < 0.001), the average voided volume increased to 192.5 mL (150-255 mL, P < 0.001), and the average residual urine volume reduced to 97.5 mL (60-145 mL, P < 0.001). No adverse events, such as wound infection or electrode translocation were detected during an average follow-up of 11.3 months. Only one of the 4 patients who received the stage Ⅱ procedure did the intermittent catheterization for one time each day.

SNM provides a minimal invasive approach for the management of DUA.