Inclusion Criteria:

• - Refractory neurogenic lower urinary tract dysfunction (nLUTD) defined by visual analogue scale on treatment satisfaction ranging from 0 to 100 (100 means maximal satisfaction with the current treatment).

All patients indicating satisfaction less than 50 are considered non-responders/having refractory overactive bladder (OAB) to current treatment.

• - No effect of medical treatment defined by antimuscarinics, beta3-agonist and alpha-blocker.

• - Patients having refractory nLUTD who intend to try SNM for relief of their symptoms.

• - Expanded Disability Status Scale (EDSS) < 5 and no progression of neurological disease within 6 months.

• - Written informed consent.

• - Able to understand the information given about the project.

Exclusion Criteria:

• - EDSS > 5, neurological disease with severe progression within the last 6 months and/or unable to manage the electronic devices.

• - Age < 18 years.

• - Any other urological pathology but nLUTD.

• - Bladder Pain Syndrome/Interstitial cystitis.

• - Any other intestinal or gynecological pathology but neurological conditional symptoms.

• - Current pelvic malignancy or clinically significant pelvic mass.

• - Previous pelvis radiotherapy.

• - Bladder injections with botulinum neurotoxin type A within 6 months before inclusion in trial.

• - Unable to manage the electronic devices.

- Inability to give an informed consent

Patients with MS often suffer from pelvic-organ dysfunctions, i.e. lower urinary tract (LUT), bowel and sexual dysfunction, aside their cerebral affection. Sacral neuromodulation (SNM) is a reversible minimal invasive procedure affecting the function of the aforementioned pelvic organs. Changes in bladder, bowel and sexual function will be monitored. Primary outcome: Success of SNM for lower urinary tract dysfunction as improvement of at least 50% in the key bladder diary variables (i.e. number of voids and/or number of leakages, post void residual) compared to the baseline values. Secondary outcome: To assess the changes in bladder, bowel and sexual function due to SNM by using subjective patient reported outcome measures, quality of life and global assessment score,

• - To assess the changes in urodynamic variables, - To assess the safety of SNM for NLUTD and.

• - To register the implantation characteristics and the need for reprogramming.

Data will be collected at Baseline 1: At inclusion Baseline 2: At evaluation after a three weeks test period Baseline 3: At randomization Baseline 4: At the end of study. The time frame of the RCT is six months. Patients with improvements of bowel symptoms only will be excluded from the trial but followed with the same questionnaires for the same time. The patients will be followed-up every 6 months for a total of 5 years.

Arms

Active Comparator: IPG turned ON

Continous neuromodulation

Placebo Comparator: IPG turned OFF

No neuromodulation

Interventions

Device: - Turning ON the neuromodulator

IPG on

Device: - Turning OFF the neuromodulator

IPG OFF