Treatment procedure

Patients underwent video-urodynamics examination (model: BV Endura; Philips, Best, The Netherlands) at baseline and in SNM testing and 6-month follow-up phases to assess bladder function and the grade of VUR. The OABSS score, bowel dysfunction score, quality of life score, and voiding diary for 3 days were also recorded in all patients^9,10.

We used the Beijing Pinchi sacral nerve electrical stimulator (Phase 1: Implantable sacral nerve stimulation electrode lead kit; Phase 2: Implantable sacral nerve stimulator kit) for SNM in this study. The specific operation steps have been reported previously¹¹. The patient was lying prone, with the hips and calves raised, knee joints slightly flexed, and toes suspended. Intraoperative three-dimensional imaging of sacral CT (Model: SOMATOM Definition AS, Siemens, Erlangen, Germany) was performed to locate the precise projection points of the bilateral sacral foramen on the body surface, and an ideal puncture path was designed. After inducing local anesthesia, the puncture was guided and performed according to the designed puncture path using intraoperative three-dimensional imaging of sacral CT in real-time. This also helped confirm whether it was located in the third sacral foramen. The best sensation and motor nerve responses were obtained in the lowest voltage. Under the guidance of the mobile C-arm fluoroscopy (model: Ziehm 8000; Ziehm, Nuremberg, Germany), the depth indicator needle was placed, the introducer sleeve and the electrode of the control system were placed, and the depths were adjusted to obtain the best sensory and motor nerve response. The fixed barbed electrode was released, a subcutaneous tunnel was made, the percutaneous extension lead was inserted, and the temporary external pacemaker was finally connected.

After phase I operation, a WeChat group was established to actively follow-up with patients. Case management and nursing intervention were used to maximize the therapeutic effect of SNM. The SNM testing phase was 2–4 weeks. After this period, the effect was re-assessed using a video-urodynamics study and questionnaire, including a 3-day voiding diary, OABSS score, bowel dysfunction score, and quality of life score. NB patients often have multiple clinical symptoms at the same time, and sometimes SNM may can’t improve all clinical symptoms at one time. In view of this situation, positive changes in parameters were defined as improvement, and improvement ≥ 50% was defined as effective. If their quality of life improves by ≥ 50%, permanent electrode implantation may also be recommended. Therefore, in this study, success during testing phase was defined as all the clinical symptoms of the NB patients were effective or the quality of life was improved by ≥ 50%¹².

The BetterStim SNM (PINS, Beijing, China) device used in the present study includes two series of implantable pulse generators (IPGs): G131 and G132; the basic components are similar to other SNM systems¹³. The stage II conversion rate refers to the percentage of patients who underwent permanent electrode implantation. The criteria for determining efficacy during the follow-up phase were the same as those during the testing phase. This study compared the differences in observation indicators above at baseline, testing, and follow-up and performed the statistical analysis. Finally, the stage II conversion rate as well as the efficiency and the occurrence of adverse events during the testing and follow-up phase, were counted. The effect was also evaluated similarly at three months follow-up after phase 2 operation.

All NB patients with VUR or residual urine volume of more than 100 mL underwent intermittent catheterization starting from SNM initiation. The frequency of catheterization depended on total daily urine output and the relative safe bladder capacity, which is the volume at the beginning of vesicoureteral reflux or cystometric detrusor pressure to 40 cmH₂O (1 cmH₂O = 0.098 kPa) during the video-urodynamics examination. The sum of the patient’s auto-urination volume and the residual urine volume in the empty bladder drained by intermittent catheterization must be less than the relative safe capacity every time.

The average quality of life score, OABSS score, and neurogenic bowel dysfunction score were calculated and recorded for all patients. In addition, the average daily catheterization frequency and the average daily catheterization volume were also recorded in the patients with voluntary voiding and intermittent catheterization. Additionally, the average voiding times, average voiding volume, and average functional bladder volume were recorded in patients with voluntary voiding using the voiding diary. The parameters of video-urodynamics examination included the maximum urine flow rate and residual urine volume, bladder compliance, detrusor overactivity (DO), maximum cystometric capacity, maximum detrusor pressure before voiding and maximum detrusor voiding pressure, detrusor-bladder neck dyssynergia (DBND), and detrusor-external sphincter dyssynergia (DESD). For patients with VUR, the bladder capacity and detrusor pressure at the beginning of reflux and the level of reflux throughout the examination were measured¹⁴.