Neurogenic bladder is a term used to describe lower urinary tract dysfunction resulting from a wide group of neurologic diseases. Several options for treatment are available, however, choosing the right treatment for each patient can be challenging. According to international guidelines, Sacral Neuromodulation (SNM) is an alternative surgical option for the treatment of medical refractory neurogenic bladder and/or bowel. It is not clear which patients are likely to benefit from SNM implantation. In this study, we aim to address this challenge by checking the efficacy and the safety of SNM in neurogenic patients compared to non-neurogenic (idiopathic) patients. Our belief that this study could help to identify patients with neurogenic conditions who most likely could benefit from SNM, and better understand its prospects and limitations in this population.

Patients who were admitted for InterStim™II implantation between 2017-2021 were included  in a single center retrospective study approved by the institutional ethics committee. All approved indications for SNM placement (refractory urge incontinence, frequency/urgency, non-obstructing urinary retention or fecal incontinence) were included in the study and divided in to two study groups based on neurogenic (Group 1) or idiopathic (Group 2) etiology for surgery. Demographics (age, gender), etiologies for neurogenic bowel/bladder, indications for InterStim™II placement (refractory urge incontinence, frequency/urgency, non-obstructing urinary retention, fecal incontinence, or double incontinence), clinical baseline and evaluation diaries were included in the data analysis.
All patients who completed one week of baseline prior to surgery, two weeks of evaluation diary and a follow-up of at least 6 weeks after InterStim™II placement, were included in the study. Clinical data based on the diary included: number of incontinence, frequency or urgency episodes in refractory urge incontinence, frequency/urgency patients; number of bowel incontinence episodes in patients with fecal incontinence; number of self-catheterizations in non-obstructing urinary retention patients.
SNM performed as a two-staged procedure in a time interval of two weeks. Successful outcome was defined by at least 50%. improvement in above mentioned symptoms documented in the patients’ diaries. InterStim™II has been placed only if the patient met criteria of success.
Number of follow-up and trouble-shooting visits were documented and compared in both study groups. All revision surgeries, removal of InterStim™II were considered as an adverse outcome.
Categorical and continuous variables were analyzed by chi-square/Fisher exact and t-student tests, appropriately. Kaplan-Meier analysis was performed to compare the time from SNM implantation till InterStim™II  removal between study groups.

57 patients (38/57, 67% female) with a mean age of 62.07±15.91 (Group 1 vs Group 2 = 62.43±14.18 vs 61.95±16.59, p=0.918) years old underwent SNM implantation during the study period and were included in our analysis (Table 1). 14/57 patients (25%) had neurogenic etiology and included in Group 1: 6/14 disc disease, 3/14 multiple sclerosis, 2/14 Parkinson’s disease, 1/14 partial sacral agenesis, 1/14 spinal stenosis and 1/14 low anterior resection syndrome. The remaining 43/57(75%) patients were included in Group 2. The most common indication for a surgery was non-obstructive urinary retention in both groups: Group 1=11/14(79%) and Group 2=27/43(63%) patients. There was no significant difference in surgery duration between study groups (Group 1= 86±24 vs Group 2=87±27 minutes, p=0.950). 46/57(81%) patients (Group 1=13/14(93%) and Group 2=33/43(77%)) had successfully placed InterStim™II at the end of two weeks of trial period.
Median follow-up after SNM implantation was 15.5±57 months and is similar in both groups (Group 1 vs Group 2, 10.79±9.77 vs 17.62±14.94 months, accordingly). Number of follow-up outpatient clinic visits for a regular checkup and/or a troubleshooting was similar in both groups. At the end of the follow-up, 33/57 (58%) patients were defined as a therapeutic success (Group 1 vs Group 2 = 9/14 (64%) vs 25/43 (58%)) with no significant difference between the groups (p=0.762).
In 10/57 patients the permanent stimulator was removed later during the follow-up. There was no significant difference in the time from SNM implantation till the InterStim™II removal between the study groups (p=0.228) (Figure 1). In 5/10 patients, the full system was removed because of essential need to perform MRI. In 4/10 patients, InterStim™II was removed due to loss of efficacy during follow-up. In one patient the device was removed because of infection. 7 revision surgeries (one in the neurogenic group) were performed due to a mechanical failure, an electrode/battery replacement, a trauma during motor vehicle accident and a seroma.

SNM is a safe procedure in neurogenic patients with a similar rate of adverse events. Patients with neurogenic bladder and/or bowel who are refractory to the conservative treatments could benefit from SNM with a similar success rate.

SNM could be offered in selected neurogenic patients.