Hypothesis / aims of study
Sacral neuromodulation (SNM) has been widely studied as a therapeutic approach in non-neurogenic overactive bladder, after failure of conservative and pharmacologic measures. Conditions such as detrusor underactivity, fecal incontinence and chronic pelvic pain are also indications for this treatment, with proven success in a fair number of trials. Recent studies have reported excellent safety and efficacy of SNM in neurogenic patients. However, the implantation of SNM devices in patients with neurogenic lower urinary tract dysfunction is still controverse, since high quality evidence in this field is still scarce. The aim of this study was to assess the efficacy of SNM therapy in a population of patients with neurogenic lower urinary tract dysfunction treated by a single surgeon.
Study design, materials and methods
We retrospectively reviewed a single surgeon experience with sacral neuromodulation in patients with neurogenic lower urinary tract dysfunction treated at a tertiary hospital from 2019 to 2022. All procedures, namely test-phase and 2nd stage (SNM device implantation) were performed under local anesthesia. We compared the Bladder Diary data of patients before neuromodulation and at 6-12 months after treatment. The medical records of these patients were also reviewed regarding adverse events and efficacy of the treatment. The standard ICS Bladder Diary was used, in its validated translation to Portuguese.
Results
A total of 24 patients with neurogenic lower urinary tract dysfunction underwent implantation of a SNM device. 2 patients were excluded from the analysis due to lack of data (unavailability of Bladder Diary data). The population of analysis was comprised of 22 patients: 13 women and 9 men, mean age of 45.3 ± 16.3 years. The neurologic conditions were: spinal cord injury (6 patients), multiple sclerosis (3), myelomeningocele (3), encephalitis (2), stroke (2), herniated disk (1), caudal regression syndrome (1), cerebral glioblastoma (1), Parkinson’s (1), miastenia gravis (1) and cauda equina syndrome (1). 8 patients were performing intermittent self-catheterization (ISC), 2 of them twice per day and the other 6 patients 5-8 times per day (after every micturition or without spontaneous voiding). Of the 22 patients that underwent the test-phase, 17 proceeded to the implantation of the permanent implant, while the other 5 failed to demonstrate a reasonable improvement after the 1st stage.
The mean change in Bladder Diary parameters before vs. 6-12 months after SNM were as follows: daily micturitions: -2.8; nocturnal micturitions: -1.2; average volume per micturition: +54 mL; incontinence episodes/24h (Bladder sensation scale 4): -3.6; urgency without incontinence episodes/24h (Bladder sensation scale 3): -1.8. Of the 8 patients performing ISC, 5 patients proceeded to the 2nd stage of the procedure, while the other 3 did not have sufficient improvement in the test-phase. One of these 5 patients stopped performing ISC, while the other 4 still need self-catheterization, although reporting less urinary incontinence between ISC. Patients with multiple sclerosis responded very well to treatment, with a mean reduction of 5 micturitions/24h, an increase of 80 mL per micturition and a reduction to 2 incontinence episodes/24h in one patient and to 0 in two other patients. Patients with myelomeningocele, caudal regression syndrome, cauda equina syndrome and Parkinson’s also responded well to SNM. In contrast, patients with spinal cord injuries benefited less from SNM. 4 patients failed test-phase; 1 patient, under CIC, had minor improvements regarding incontinence between self-catheterization, whereas 1 patient had a decrease of 5 micturitions/24h, increase in 25 mL/micturition and a decrease from 2 to 0 episodes of incontinence/day.
Change in Bladder Diary data was not different in males vs females, nor variable with age. Despite not assessed with the Bladder Diary, improvement in bowel-related symptoms was routinely reported by patients. No adverse events were reported, except minor discomfort near the gluteal incision caused by the device. In one patient, the device had to be removed 2 years after implantation, in order to perform an MRI.
Interpretation of results
While not formally recommended in most guidelines, recent data has shown that sacral neuromodulation may have a role in the treatment of neurogenic lower urinary tract dysfunction. In fact, since the exact mechanism of action of sacral neuromodulation has not yet been completely explained, and given the wide heterogeneity of neurological patients, high-quality trials in this field are very difficult to conduct. Therefore, the only evidence available so far is derived from case-reports or small non-controlled cohorts.
In the present study, we analyze a cohort of patients with neurogenic lower urinary tract dysfunction treated with SNM. In 23% of patients there was not a sufficient improvement in test-phase to advance to the implantation of the permanent device, a figure similar to the published literature. In the patients submitted to implantation of the permanent device, a reduction in symptom severity was observed, as observed in Bladder Diary changes. The ICS Bladder Diary (in this case, the Portuguese version) is, in our view, an excellent tool to measure changes in this setting. It is a validated, non-invasive method of assessing patient-reported outcomes. Other important outcomes not measured in the Bladder diary, such as need of ISC, bowel-related symptoms or quality of life also seem to be affected positively by SNM. Interestingly, symptoms related to bowel movements were reported to improve faster than urinary symptoms, which often require reprogramming of the SNM device.