Controversies in fecal incontinence

Abstract

Fecal incontinence is a common condition that can significantly impact patients’ quality of life. Obstetric anal sphincter injury and anorectal surgeries are common etiologies. Endoanal ultrasound and anorectal manometry are important diagnostic tools for evaluating patients. There are various treatment options, including diet, lifestyle modifications, drugs, biofeedback therapy, tibial and sacral nerve neuromodulation therapy, and surgery. In this editorial, we will discuss current controversies and novel approaches to fecal incontinence. Screening for asymptomatic anal sphincter defects after obstetric anal sphincter injury and in patients with inflammatory bowel disease is not generally recommended, but may be helpful in selected patients. The Garg incontinence score is a new score that includes the assessment of solid, liquid, flatus, mucous, stress and urge fecal incontinence. Novel tests such as translumbosacral anorectal magnetic stimulation and novel therapies such as translumbosacral neuromodulation therapy are promising diagnostic and treatment options, for both fecal incontinence and neuropathy. Home biofeedback therapy can overcome some limitations of the office-based therapy. Skeletal muscle-derived cell implantation of the external anal sphincter has been further studied as a possible treatment option. Sacral neuromodulation may be useful in scleroderma, congenital fecal incontinence and inflammatory bowel disease but merits further study.

Key Words: Fecal incontinence; Endoanal ultrasound; Anal sphincter defects; Biofeedback; Neuropathy; Sacral neuromodulation

Core Tip: In this article we will discuss some controversies and novel approaches to diagnosing and treating fecal incontinence, namely screening for asymptomatic anal sphincter defects, new incontinence scores, novel tests such as translumbosacral anorectal magnetic stimulation and novel therapies such as translumbosacral neuromodulation, home biofeedback therapy, skeletal muscle-derived cell implantation and unconventional indications for sacral neuromodulation.

TO THE EDITOR

Fecal incontinence (FI) has a global prevalence of 8%, affecting approximately 1 in 12 individuals worldwide, and has a higher prevalence in women, and those aged ≥ 60 years[1]. It can profoundly affect the patient’s quality of life and lead to significant social stigma[1].

Obstetric anal sphincter injury is one of the most common causes of FI and can frequently be occult and asymptomatic[2,3]. Other possible causes are congenital malformations, neurological diseases, or anorectal surgeries[2].

In modern clinical practice, endoanal ultrasound and anorectal manometry are two important diagnostic tools that are commonly used for the diagnosis of patients with FI[2]. Endoanal ultrasound is the gold standard for evaluating internal and external anal sphincter integrity[4]. Anorectal manometry allows resting and squeeze pressure measurements, rectal sensation and other parameters that are related to internal and external anal sphincter and rectal function, respectively[5,6]. Treatment is often multidisciplinary and includes diet, lifestyle modifications, drugs, biofeedback therapy, tibial and sacral neuromodulation (SNM) therapy, and surgery to repair anal sphincter defects[2,7].

In this article, we will discuss some controversies and advances for the diagnosis of FI, namely, screening of asymptomatic sphincter defects, a new scoring system and translumbosacral anorectal magnetic stimulation (TAMS) for the diagnosis of neuropathy. We will also cover novel approaches for treating FI, including translumbosacral neuromodulation therapy (TNT), home biofeedback therapy, skeletal muscle-derived cell implantation, and unconventional indications for SNM.

SCREENING FOR ASYMPTOMATIC ANAL SPHINCTER DEFECTS

Obstetric anal sphincter injury

Obstetric trauma is a major cause of FI and anal sphincter laceration[2]. A landmark study published by Sultan et al[8] in 1983 showed that 35% of vaginal deliveries by primiparous women were complicated by an occult anal sphincter injury that persisted in all studied cases at six months. Only 3% of the primiparous women had a laceration that was apparent at the clinical examination, and only approximately 30% of women with anal sphincter laceration had bowel symptoms[8]. A meta-analysis showed that occult sphincter defects were observed in 13% of vaginal deliveries (n = 3688), with FI occurring in 14%. Residual sphincter defects were diagnosed in 55% of women following primary repair (n = 7549), with FI occurring in 38%[3]. Many of these defects are not corrected or repaired, with a high rate of residual defects[3]. A recent network meta-analysis showed that higher degrees of anal tears are associated with worse clinical outcomes[9].

Many of these women remain asymptomatic, but FI can occur later in life, especially after menopause, and may be influenced by other factors, such as aging and multiple vaginal deliveries, that can further compromise anal sphincter function[8].

Three-dimensional endoanal ultrasound is the gold standard technique for evaluating anal sphincter integrity and diagnosing anal lacerations[4,10]. This technique may allow the diagnosis of lacerations that otherwise would not have been detected. Furthermore, the immediate recognition and surgical repair of this defect can reduce the risk of developing severe FI in the future. A randomized controlled trial showed the benefit of using endoanal ultrasound immediately after vaginal delivery to detect anal sphincter lacerations compared to clinical examination alone, and those with identified defects received immediate surgical correction[11]. The trial included 752 primiparous women without a clinically evident anal sphincter defect. Severe FI was reported in 3.3% of women in the ultrasound group (all lacerations were treated) compared to 8.7% in the control group at three months after childbirth (P = 0.002) and in 3.2% of women in the ultrasound group compared to 6.7% in the control group at one year after childbirth (P = 0.030)[11].

Screening for asymptomatic anal sphincter defects that can occur after vaginal deliveries is not routinely recommended. However, more studies are needed regarding the potential benefit of this screening, especially in high-risk women. Endoanal ultrasound requires practice and special equipment that is not widely available in obstetric units[10]. However, some experts have recommended screening high-risk women for anal sphincter defects using three-dimensional- endoanal ultrasound or four-dimensional transperineal ultrasound 10-12 weeks after vaginal delivery, namely those with a maternal age of ≥ 35 years, vaginal birth after cesarean delivery, prolonged second stage of labor, and diagnosis of obstetrical anal sphincter injury. The use of forceps, shoulder dystocia, and macrosomia are also risk factors for anal sphincter injury[10].

Inflammatory bowel disease

Perianal fistulas affect around 25% of patients with Crohn’s disease[12]. A meta-analysis showed that FI was more common in patients with inflammatory bowel disease (IBD) than in healthy controls, and it can occur in 24% of patients with IBD without ileal pouch-anal anastomosis[13]. In this patient population, FI is multifactorial and can be associated with abnormal rectal sensitivity, compliance, and sphincter damage[13]. Among patients with IBD, FI is more common in those with than without perianal Crohn’s disease and can impact their quality of life[14]. A systematic review evaluating the burden of complex perianal fistulas in patients with Crohn’s disease showed that up to 59% were at risk of FI[15].

In patients with perianal Crohn’s disease, anal surgery for fistulas and abscesses can lead to occult and asymptomatic anal sphincter laceration[16]. A prospective study involving 16 patients with inactive perianal Crohn’s disease, previously submitted to anorectal surgery, found a laceration of the internal anal sphincter and/or anal scarring in nine (56%), of which five (56%) had never experienced FI[16].

Currently, the European Crohn’s and Colitis Organization recommends a C-section for women with active perianal disease, prior rectovaginal fistula, and after restorative proctocolectomy[17]. The diagnosis of an occult anal sphincter laceration is especially important in cases where a surgical bowel reconstruction is planned or in pregnant women with inactive perianal disease who are likely to have a vaginal delivery[16]. No recommendations exist for the routine screening of occult anal sphincter laceration in these patients, and more studies are needed to prevent FI or to recognize the disease early to prevent further co-morbidity.

SCORING SYSTEMS

Scoring systems are routinely used to help clinicians assess FI severity, namely the Cleveland Clinic or Wexner score[18], the St. Marks Hospital or Vaizey’s score[19], and FI severity index[20].

Recently, a new scoring system for FI was developed, the Garg incontinence score (GIS)[21]. This system includes the assessment of six types of FI: Solid, liquid, flatus, mucous, stress and urge. When compared with the other scoring systems, this new score includes stress FI as a parameter. In the GIS, the weight for each FI is also different and was developed by using patients and laypersons perspective, as patients’ and surgeons’ perceptions of FI severity did not correlate well in this study. Further studies are necessary to validate this new tool[21].

DIAGNOSTIC TESTS AND TREATMENTS

TAMS

Electromyography or pudendal nerve terminal motor latency testing has several limitations for evaluating neuropathy in patients with FI, and they are painful and often unreliable[22]. TAMS is a new technique for evaluating lumbar and sacral neuropathy using an anorectal probe and applying magnetic energy to the back to indirectly stimulate the lumbar and sacral plexus nerves that innervate the anorectum bilaterally.

A 2011 study evaluated TAMS in 39 subjects with spinal cord injury and 14 healthy controls[23]. Pudendal nerve terminal motor latency was also performed. In total, 46% of the patients with spinal cord injury also had FI: 33% had constipation, and 21% had mixed symptoms. The results showed that 95% of patients with spinal cord injury had prolonged motor evoked potentials that were significantly prolonged at all sites compared to the healthy controls[19]. Pudendal nerve terminal motor latency was significantly less sensitive than TAMS for detecting neuropathy in these patients[23].

A 2014 study evaluated TAMS in 50 patients with FI (30 underwent both TAMS and the pudendal nerve terminal motor latency test) and 20 healthy controls[24]. TAMS also seemed to perform better than pudendal nerve terminal motor latency in this study.

A 2022 study used TAMS to evaluate lumbar and sacral neuropathy in 144 patients with FI, 76 mixed FI/constipation, and 31 healthy controls[22]. The results showed that all lumbar and sacral motor-evoked potential latencies were significantly prolonged in the FI and mixed groups compared to the healthy controls.

TAMS seems to be a promising and safe method for evaluating lumbar and sacral neuropathy in patients with FI, but more data are needed.

TNT

TNT is a novel and noninvasive therapy designed to improve neuropathy, anal muscle strength, stool awareness, and rectal capacity in patients with FI.

A study by Rao et al[25] evaluated TNT in 33 patients with FI who did not respond to conservative treatments. The patients were randomized into three groups, and received TNT at 1, 5, or 15 Hz frequency, weekly for six weeks. Each subject received 600 stimulations across four sites (right or left lumbar/right or left sacral). This study evaluated the possible benefits of TNT in FI severity and manometric and neurophysiological parameters. The results showed that FI episodes/week decreased significantly in all groups compared to baseline. However, the responder rate i.e. 50% reduction in FI episodes/week (the primary outcome) was significantly higher in the 1 Hz group than in the 5 Hz and 15 Hz groups. Manometric parameters, such as the squeeze pressure and rectal capacity, were also significantly improved in the 1 Hz group compared to baseline, as well as improvement in their quality of life. There was a shortening of anal motor evoked potentials latencies with the 1 Hz frequency, suggesting that bilateral lumbar and sacral anal neuropathy were significantly improved (less within the other two groups). The procedure seemed safe, and only one adverse event was considered study-related: One patient experienced worse back pain and numbness that resolved. In a further study, they showed that TNT improved lumbosacral plexus neuropathy, with anorectal-cortical evoked potentials, anal sphincter function, and rectal capacity showing significant mechanistic improvement with 1 Hz repetitive magnetic stimulation[26]. TNT also shortened the cortical evoked potentials latency time and reduced the signaling time between the anorectum and brain, which can be associated with increased awareness of stool perception that can prevent stool leakage[26].

This procedure seems to improve FI by neuromodulation[26], and these promising results require further exploration in larger sham controlled studies.

Home biofeedback therapy

While office biofeedback therapy is recommended for FI, it is time-consuming and requires multiple office visits. Some studies have explored the possibility of home-based biofeedback therapy as a treatment option in order to overcome these limitations.

A randomized controlled trial compared home electrical stimulation (n = 18) with standardized biofeedback therapy (n = 18) in women with FI[27]. Home electrical stimulation was performed daily and office-based biofeedback therapy was performed weekly for six weeks. Home stimulation was associated with significant improvements in Vaizey incontinence scores, anxiety, frequency of leaked solid stool, and pelvic floor muscle strength[27].

A more recent randomized controlled trial compared home biofeedback therapy (n = 20) with office biofeedback therapy (n = 10) for FI[28]. The home biofeedback therapy was performed daily using a new United States Food and Drug Administration-approved device that allows both mechanical resistance training and electrical stimulation with tailored voice-guided instructions. The office-based therapy was performed weekly for six weeks. Weekly FI episodes decreased significantly after home biofeedback therapy, quality of life improved significantly and the resting and maximum squeeze sphincter pressures also increased. Fifteen of the 20 subjects (75%) in the home biofeedback therapy adhered to treatment (using the device at least six days a week). The response rate was 65% in the home biofeedback arm and 60% in the office biofeedback arm. No serious adverse events were reported. Home biofeedback therapy was non-inferior to office-based therapy[28].

These two studies show promising results for home-based biofeedback, but more data are needed.

Skeletal muscle-derived cell implantation

In 2010, an observational pilot study described the injection of autologous myoblasts into the external anal sphincter of 10 patients with severe FI who were refractory to medical treatments[29]. All cases were due to obstetric external anal sphincter injury. Muscle cells were obtained from the pectoralis muscle. The injection was performed under ultrasound guidance, and the patients were followed up for one year. The procedure seemed safe and was well tolerated. The patients’ incontinence scores had significantly decreased and their quality of life had significantly increased at 12 months. While the maximum anal squeeze pressure did increase significantly at one and six months, it returned to baseline at one year. There was also no significant change in the thickness of the anal sphincters[29]. Other non-randomized studies have further explored this treatment option for FI[30,31].

A phase 2 randomized placebo-controlled study evaluated the use of autologous myoblasts in 24 women with severe FI refractory to conservative treatment (randomization 1:1) and followed them for one year[32]. All women had external anal sphincter deficiency (< 30% circumference), and nine also had internal anal sphincter defects. Muscle cells were obtained from a quadriceps biopsy. The incontinence scores were significantly lower in the autologous myoblasts group than in the placebo group at one year but not at six months, with a concomitant improvement in quality of life. There were no significant functional or structural changes compared to baseline in the autologous myoblasts group, including in manometric and endoanal ultrasound evaluation parameters. No serious complications were described[32].

A more recent multicenter randomized placebo-controlled trial included men and women with FI who were randomized into control (n = 79) and low-dose (n = 83) or high-dose (n = 75) cell groups[33]. All patients had external anal sphincter damage. Pelvic floor electrical stimulation was performed before and after treatment. Incontinence episodes were significantly lower in the high-dose cell group than in the control group at six months (primary outcome) but did not differ significantly between the low- and high-dose cell groups. The improvements tended to persist or increase in the high-dose cell group from 6 to 12 months, while the opposite was observed in the control and low-dose cell groups. This study also examined subgroups of patients that could better respond to treatment. In this context, patients with limited FI durations and high incontinence episode frequencies had better treatment responses[33].

There are few studies in this field, most with up to one year of follow-up. Studies have shown that this procedure is safe in patients with FI, leading to decreased incontinence scores and improved quality of life. However, none of these studies have shown improvements in manometric or endoanal ultrasound parameters.

UNCONVENTIONAL INDICATIONS FOR TREATMENT WITH SNM

Scleroderma

FI is a possible manifestation of scleroderma[34] and can occur in 38% of these patients[35]. The etiology is multifactorial, including a thinner, scarred, and/or atrophic internal anal sphincter. FI in patients with scleroderma is typically difficult to treat and has unsatisfactory results[36].

A few studies have examined the effectiveness of SNM in treating FI in a small number of patients with scleroderma[37,38]. However, they have reported conflicting results. One study by Kenefick et al[37] included five patients who failed to respond to conventional therapies. While one patient failed temporary placement, the four who achieved permanent implantation were all continent at a median follow-up of 24 months. Another study by Butt et al[38] included 10 patients, of whom only two showed improvement with temporary implantation. Of these two patients, only one achieved a favorable outcome at one year.

Given that FI is difficult to treat in patients with scleroderma, further studies are needed to explore SNM as a treatment option for these patients.

Congenital FI

Only one study has examined SNM in patients with congenital FI, including four patients: Two with Hirschsprung disease, one with rectal atresia, and one with imperforate anus/distal sacral agenesis[39]. All patients failed conventional therapy and were required to have total or partial integrity of the anal sphincter to be included. All four patients underwent permanent implantation of the SNM after a temporary period. Two patients showed long-lasting improvement with SNM (11 years and 3 years post-implantation), and two had the device removed due to infection (four years post-implantation) or failure (five years post-implantation).

IBD

Data evaluating SNM as a treatment option in patients with perianal Crohn’s disease, anal sphincter laceration, and FI are scarce. A study by Vitton et al[40] evaluated SNM in five patients with perianal Crohn’s disease and internal and external anal sphincter lacerations causing FI. All patients underwent permanent implantation after three weeks of temporary stimulation, and the median follow-up was 14 months. Their Wexner score and quality of life improved, and no serious adverse events were reported during the follow-up.

CONCLUSION

Routine screening for occult anal sphincter lacerations after vaginal delivery or patients with perianal Crohn’s disease with previous anorectal surgery is not generally recommended. However, a lack of early recognition may predispose such patients to FI. Whether routine screening with anal ultrasound could be beneficial in high-risk women or high-risk patients with IBD merits further study. Scoring systems are routinely used in clinical practice to evaluate the severity of FI. GIS is a new scoring system developed using patients and laypersons perspective, and this includes the assessment of solid, liquid, flatus, mucous, stress and urge FI, each weighted differently. Further validation studies are needed. TAMS, is a noninvasive diagnostic technique for evaluating anorectal neuropathy, and TNT, is a noninvasive treatment option for FI that can improve symptoms and neuropathy, and should be further explored in larger controlled studies. Biofeedback therapy is a vital part of FI treatment. Recent studies suggest that home-based biofeedback therapy is promising and could improve access as well as reduce costs. Studies on skeletal muscle-derived cell implantation of the external anal sphincter have shown that this procedure is safe and improves symptoms. However, no significant functional or structural changes have been reported to date. Further studies are needed to assess its clinical utility and feasibility in a routine clinical setting. FI can be associated with scleroderma, congenital anorectal diseases, IBD, and SNM could be a treatment option when these patients fail to respond to conventional therapy. However, more data are needed.