Table 1. Studies on SNM for NLUTD (published from 2011 to 2019).
| Reference and level of evidence (LE) | Year Study type | Underlying neurological disease (indication for SNM) | N | Definition of Success during test phase | Outcomes |
|---|---|---|---|---|---|
| Arlen et al. ( 13 ) LE 4 | 2011 RCS Case-control study | Patients with or without prior spinal surgery (OAB, NOR) | 32 | ≥ 50% symptom improvement in bladder diaries | Clinical success achieved in selected patients with LUTS and a history of spinal surgery; urge incontinence less likely to improve. Mean follow-up of 2.3 years; Complications not reported |
| Lombardi et al. ( 14 ) LE 4 | 2011 PCS | Incomplete spinal cord lesions (OAB and/or NOR) | 75 | ≥ 50% symptom improvement in bladder and bowel diaries | 14/37 (38%) subjects with two functional pelvic dysfunctions maintained notable clinical improvement with a median follow-up >3 years |
| Chaabane et al. ( 15 ) LE 4 | 2011 RCS | Various neurological diseases* (OAB in 34, NOR in 15, NOR+DO in 13) | 62* | Clinical and urodynamic improvement ≥ 50% and symptom recurrence after stopping stimulation | 41 (66.1%) had more than 50% improvement on urodynamic evaluation and bladder diary and 37 were implanted. With a mean follow-up of 4.3 ± 3.7 years, results were maintained in 28 (75.7%). SNM failed on average 12.0 ± 12.4 months after implantation |
| Minardi et al. ( 8 ) LE 4 | 2012 RCS | MS (OAB, NOR) | 25 | > 50% symptom improvement in bladder diaries and/or >50% decrease in daily catheterizations and increase in voided volumes | 15 (60%) patients received the IPG. After a mean follow-up of 61.2 months, 10 patients still had a functioning device. SNM did not help MS patients with urinary retention due to detrusor underactivity. |
| Lansen-Koch et al. ( 11 ) LE 4 | 2012 RCS | Spina bifida (Fecal or urinary incontinence, constipation, NOR or a combination) | 10 | ≥ 50% symptom improvement | Only 3/10 (30%) patients succeeded and received the permanent IPG. In one patient the electrode could not be implanted; .one patient developed skin erosion at the stimulator site in the buttock, requiring replacement to the abdomen. |
| Groen et al. ( 16 ) LE 4 | 2012 RCS | Spina bifida (Unclear pattern of NLUTD; 2 patients with UI) | 3 | ≥ 50% symptom improvement | The IPG was removed in all 3 patients due to disappointing results (time from implantation to removal was not reported). |
| Peters et al. ( 3 ) LE 4 | 2013 PCS | NLUTD (Stroke in 17, MS in 13, PD in 10, incomplete SCI in 4, and others) | 71 | ≥ 50% symptom improvement in bladder diaries | 63 of 71 (88.7%) with a neurological disease and 241 of 269 (89.6%) without a neurological disease received the IPG (P = .82). Complications, revisions/explants, and reprogramming sessions were similar in the 2 groups |
| Lombardi et al. ( 17 ) LE 4 | 2013 RCS | Incomplete SCI (ASIA C or D) (NOR) | 77 | 50% reduction of volume per catheterization and number of catheterizations per day | 11/29 patients (31%) reached a BCI > 100. Most voided with Valsalva maneuver, with vesical pressure 72-95cm H20. 10/29 patients became nonresponsive in a mean follow-up of 54 months. |
| Andretta et al. ( 18 ) LE 4 | 2014 RCS | MS (Storage in 41%, voiding in 24%, mixed in 35%) | 17 | Not stated | 75% had significant and lasting improvement in LUTS and in quality of life. SNM was discontinued after a mean time of 66 months due to disease progression in 2 cases and loss of efficacy in 3. |
| Lombardi et al. ( 19 ) LE 2b | 2014 PCS | Incomplete SCI (NOR) | 50 | Concomitant reduction by at least 50% of volume per catheterization and catheterizations per day | 36 patients received the IPG. Significant increase in urinary flow and decrease in residual urine were documented. 11/34 patients at follow-up were ‘inconstant responders’, as they returned to baseline symptoms but responded again with an implant on the contralateral S3. All but one failure occurred more than 3 years after the previous implant. |
| Chen et al. ( 20 ) LE 4 | 2015 RCS | Incomplete SCI (Neurogenic bladder and bowel dysfunction) | 23 | At least 50% clinical improvement (bladder diary, residual volume and the Wexner questionnaire for constipation) | IPG implanted in 13 (56.5%) patients, including 4 who still used intermittent catheterization. During a mean follow-up of 17.5 months, 1 patient failed and 1 patient developed bilateral vesicoureteral reflux. |
| Engeler et al. ( 21 ) LE 4 | 2015 PCS | MS (OAB, or LUTS caused by detrusor underactivity or detrusor sphincter dyssynergia, or both) | 17 | >70 % improvement in voiding and storage symptoms on voiding diary | At 3 years of follow-up, voided volume improved from 125 to 265 mL, post void residual from 170 to 25 mL, micturition frequency from 12 to 7/day and number of UI episodes/day from 3 to 0. Satisfaction was 80%. Loss of clinical benefit in 2 patients; there were no major complications. |
| Wöllner et al. ( 22 ) LE 4 | 2016 RCS | Various neurological diseases Incomplete SCI in 35 patients (70%) (Neurogenic DO, neurogenic urinary retention) | 50 | Objective improvement of voiding frequency and daily pad usage, or post-void residual urine. | IPG implanted in 35 patients (70%). In 26 patients with refractory DO, daily frequency was reduced from 9 to 6, and pad use was improved from 2.6 to 0.6/day; nine patients with NOR had post void residue reduced from 370 to 59 mL; At the last follow-up, SNM was in use in 32 (64%) patients. |
| Okafor et al. ( 12 ) LE 4 | 2016 RCS | Various neurological diseases | 80** | Not stated | Progression to stage 2 SNM was 90%. Revision rate=46%; Explantation rate=33% (most common reason was loss of efficacy). |
| Greenberg et al. ( 23 ) LE 4 | 2019 RCS | Parkinson Disease | 14 | ≥ 50% symptomatic improvement | IPG implanted in 8 patients. Decreased urinary frequency up to 18 months compared to baseline: 7.70±8 voids/24 hours vs. 15.6±2.2 voids/24 hours (p<0.05). No patients required explantation of their SNM device. |
| Sharifiaghdas ( 24 ) LE 4 | 2019 RCS | Spinal dysraphism in 6 and traumatic spinal cord in 2 | 8 | ≥ 50% reduction of UI, in urinary frequency, post-void residual volume and need for intermittent catheterization | Positive clinical response was achieved in seven (85%) at a mean follow-up of 14.25 months. Three patients became capable to stop clean intermittent catheterization |
| Peyronnet et al.( 10 ) LE 4 | 2019 RCS | Parkinson´s Disease | 20 | ≥ 50% reduction in storage symptoms | IPG implanted in 13 patients, 7 patients still presented response at 20-month follow-up. Four explanations of the device were performed due to loss of efficacy (n= 3) and ‘discomfort’ (n=1). |
RCS = retrospective case series; P = permanent sacral neuromodulation; T = test phase; PCS = prospective cohort study; NR = not reported; CR = case report; LE = level of evidence; OAB = overactive bladder syndrome; NON = non-obstructive retention; DO = detrusor overactivity; DSD = detrusor-sphincter dyssynergia; SNM = sacral neuromodulation; LUTS = lower urinary tract symptoms; NLUTD = neurogenic lower urinary tract dysfunction; BCI = bladder contractility index, MS = multiple sclerosis, PD = Parkinson’s disease, SCI = spinal cord injury, IPG = implantable pulse generator; UI = urinary incontinence.
* n = 62 patients: Multiple sclerosis = 13; Incomplete spinal cord injury = 13; Peripheral neuropathy = 8; Parkinson’s disease = 4; Myelitis/encephalitis = 4; Stroke = 4; Acquired brain injuries = 3; Cerebral palsy = 2; Central nervous system tumor = 2; other = 9.
**n= 80 patient: SCI = 23; MS = 19; Stroke = 12; cerebral palsy = 10; peripheral nervous system disorders = 10; PD = 6.