Sacral Neuromodulation Therapy for Urinary and Fecal Incontinence in Patients With Multiple Sclerosis: Report of 6 Cases and Literature Review

Multiple sclerosis (MS) is an autoimmune disease primarily targeting the myelin-producing oligodendrocytes of the central nervous system and can cause demyelination and axonal loss in the brain, brainstem, cerebellum, and/or spinal cord.¹ These demyelinated lesions give rise to bladder problems in 50% to 90% of patients with MS, including a high prevalence of overactive bladder (OAB) and urinary incontinence (UI).^2,3 The latter was even more frequent in patients with MS if they were disabled and female.⁴ Fecal incontinence (FI) is found to affect more than 50% of patients with MS, which is far greater than the 2% to 20% prevalence in the general population.⁵ These symptoms impact the quality of life and social interactions of patients with MS and create additional burdens for caregivers.⁵

The current management of UI and FI in patients with MS begins with first-line behavioral modifications such as bladder training, pelvic floor physical therapy, fluid management, fiber, antidiarrheals, and dietary changes. Historically, second-line therapies for UI are pharmacotherapies, including anticholinergics and ß₃-adrenergic agonists, and/or intermittent self-catheterization. Traditionally, third-line therapy options are intradetrusor botulinum toxin, consisting of repeated treatments every 6 to 12 months, or posterior tibial nerve stimulation, consisting of a weekly office-based therapy for 3 months. Advanced therapy is sacral neuromodulation (SNM), involving placement of a neuromodulation lead and a subcutaneous pulse generator.⁶

Sacral neuromodulation has been an effective treatment for UI and FI since its approval by the US Food and Drug Administration in 1997.² The mechanisms of action for SNM include inhibition of afferent sensory nerves of the bladder and rectum in the spinal cord, modulation of efferent voluntary somatic input to the bladder, and stimulus of autonomic motor nerves.^1,7 Recent studies report 90% effectiveness in clinical trials for treatment of UI and FI.⁸ However, SNM was originally incompatible with MRI, and SNM is less accepted by insurance carriers for patients with neurologic disorders, including MS. The Centers for Medicare & Medicaid Services (CMS) and many insurance companies continue to exclude those who experience UI due to a neurologic condition, ie, cerebrovascular accident, spinal cord injury, MS, detrusor hyperref lexia, and other types of chronic neurogenic voiding dysfunctions.⁹

In this study, we retrospectively evaluated the efficacy and safety of a newer, fully MRI-compatible SNM treatment for 6 patients with MS who were experiencing refractory UI, FI, or both before treatment.

METHODS

Under an institutional review board–approved protocol (WCG IRB), a retrospective medical record review was undertaken to identify all patients with MS who sought treatment for UI and FI at the Continence Center of Nevada Surgical in Reno, Nevada. Since 2017, all patients have provided detailed responses to questionnaires regarding bowel and bladder symptoms and the presence of neurologic conditions. Informed consent was obtained from all individual patients regarding responses to questionnaires being used for clinical assessments or publication in any medium. In 2022, 6 patients with MS were identified in the database. All were ambulatory, 2 with the use of assist devices (cane or walker); no one used a wheelchair. Disease severity was not quantified, and to our knowledge, no patient referred to the center with MS declined or was refused SNM therapy. The patient characteristics are described in TABLE 1. After SNM implant (Axonics Inc), patients reported, in person or by phone, updated responses to the bladder and bowel questionnaires. The Michigan Incontinence Symptom Index (M-ISI)¹⁰ and the Fecal Incontinence Severity Index (FISI)¹¹ were used to assess the severity of symptoms before and, on average, 9 months after therapy.

Patient Characteristics and M-ISI and FISI Scores

In coordination with their neurologists, each patient had a percutaneous nerve evaluation. During the procedure, a localization needle was placed into each S3 foramen, and motor response to stimulation was carefully observed, with assessment of anal bellows, perineal lift response, and great toe flexion. In subsequent days, each patient reported that the trial was successful, and SNM implant via the S3 foramen under fluoroscopic guidance was subsequently performed in the operating room using local anesthetic with sedation, with a median implant procedure time of 28 minutes. There were no adverse events during a minimum of 12 months of follow-up.

RESULTS

In this study, 6 patients with MS who sought treatment for UI, FI, or both were identified in the database. Each patient had failed medication therapy and pelvic floor therapy with exercises and biofeedback. One had previous botulinum injections and 1 had a failed previous bladder sling. All 6 patients experienced relief after SNM, as measured by their M-ISI and FISI scores. As depicted in Table 1, the median M-ISI score before SNM was 28 and after SNM was 6. The 2 FISI scores were 41 and 42 prior to SNM and both were 0 after SNM.

All the patients reported that SNM was successful. In addition to the improvements in UI and FI, all the patients reported significant improvements in quality of life. Patients described feeling relieved and having peace of mind going about their daily lives. Patient 1 reported being able to “take a vacation for the first time in years” after noticing that she could go longer periods of time without needing to use the bathroom. Patient 4 reported experiencing “peace of mind” and that the treatment “gave back [his] life.” This has led to an improvement in his sex life and intimacy as he is “no longer worried about having any accidents.” He reported being able to return to work and resume teaching because of SNM therapy. These anecdotes are consistent with the clinical findings that SNM allows patients to reach the toilet in time and enables complete emptying of the bladder, significantly improving quality of life, volume voided, urgency, and urge UI.¹²

DISCUSSION

Similar to other reports in the literature on older devices, this small case series, using newer, MRI-compatible devices, found that SNM was a very effective therapy, resulting in significant improvement in UI and FI for patients with MS.

Summary of Literature Review

According to a 10-year retrospective cohort study with 4461 patients with and without MS, more patients with MS were diagnosed as having UI and FI than those without MS.¹³ Also, FI and UI occur at a younger age in patients with MS than in the general population. Sacral neuromodulation acts via neurologic mechanisms, offering logical plausibility to treat neurogenic incontinence. Even a single previous episode of FI can cause anxiety and lead to isolation and self-imposed restrictions to avoid the risk of embarrassment, shame, or humiliation associated with that incident.¹⁴

Although not completely understood, SNM’s stimulation of the S2-S3-S4 nerve roots is thought to provide relief through a combination of efferent motor stimulus, blocking afferent inputs, and blunting spinal cord reflex responses and brain responses to detrusor and pelvic floor musculature.^1,14 Published studies support the conclusion that SNM provides relief of UI and FI in patients with neurogenic incontinence, as does this series.^5,12,15,16 In practice, however, patients with MS experiencing UI or FI are often considered ineligible for SNM or denied insurance coverage based on preliminary SNM studies, despite more recently published studies demonstrating its efficacy.^5,7,12,15,16 In a prospective cohort study, 17 patients with MS were treated with SNM, and 16 of them (94%) had greater than 70% improvement in urinary dysfunction.¹² In a 2018 study, SNM was found to improve FI in 59% to 82% of patients with MS.⁵ A 4-year prospective study found a statistically significant decrease in involuntary stool loss and urge defecation numbers.⁷ In a retrospective case series study, 60% of patients (15 of 25) reported clinically significant improvement in symptoms of frequency and incontinence, a decrease in the number of catheterizations, and an increase in void volume.¹⁵ A multicenter study analyzed therapeutic success and quality of life over 36 months and reported statistically significant improvements in urinary symptoms.¹⁶

The present review of the literature found generally favorable results for SNM as a treatment for FI and UI in patients with MS. Engeler et al¹² reported that SNM treatment had a high success rate after the failure of conservative treatment options. It improves the volume voided, urgency, and urge UI and reduces postvoid residual. These effects were achieved early in treatment and remained stable thereafter.¹² Minardi and Muzzonigro¹⁵ found that SNM was a valid therapeutic option in patients with lower urinary tract symptoms due to MS. Their study confirmed a significant decrease in urgency and frequency among SNM patients and an overall improvement in quality of life.¹⁵ Pericolini et al¹⁷ also determined that SNM is an effective and safe therapeutic option for treating lower urinary tract symptoms in patients with MS. In addition, Worsøe et al¹⁴ also documented SNM and its improvement in FI symptoms.

Limitations of this case series include its small size, limited generalizability, limited duration of follow-up, and that MS disability severity was not formally assessed as an independent variable. These would be important factors to include in larger-scale assessments of SNM in this patient population because SNM may not offer the same effectiveness in more advanced cases of MS. Strengths of this case series include its echoing previous findings in the literature and its raising awareness of MRI-compatible SNM as a therapy deserving of more study.

This experience with SNM in patients with MS revealed no adverse events. None of the patients in this series reported difficulty charging the device, but challenges with charging among older patients and increased, approximately 15-year, battery longevity have led us to a default recommendation of the newer, nonrechargeable device. None of the studies before the present series demonstrated adverse events or raised concern of risks that might warrant restricting SNM therapy for patients with MS. Newer SNM devices are fully compatible with 3-T MRI technology, with the recommendation that the SNM device be temporarily switched off during the scan using the accompanying remote control. Given the neurologic mechanism of pelvic floor dysfunction and incontinence in MS, effective therapy may work through a neuromodulatory mechanism.

The published literature reveals no rationale for the CMS and insurers to exclude patients with MS from effective pelvic floor therapy. The severe negative impact of incontinence and the high success at restoring continence and quality of life found in this and other studies of SNM are additional arguments that patients with MS should no longer be excluded from receiving SNM therapy by insurers. Larger-scale clinical assessment is warranted to determine the best candidates and to confirm the thesis that SNM should be considered when counseling patients with MS on treatment modalities and quality of life related to refractory UI and FI.

PRACTICE POINTS

Fecal and urinary incontinence are highly prevalent among patients with multiple sclerosis and significantly reduce quality of life.

Sacral neuromodulation is an effective therapy for urinary and fecal incontinence for some patients with multiple sclerosis, both in this series and in the reported literature.

Sacral neuromodulation is a safe, reversible, 30-minute procedure that can obviate the need for long-term anticholinergic medication or more invasive surgery.