Biofeedback for Pelvic Floor Disorders

Abstract

Defecatory disorders can include structural, neurological, and functional disorders in addition to concomitant symptoms of fecal incontinence, functional anorectal pain, and pelvic floor dyssynergia. These disorders greatly affect quality of life and healthcare costs. Treatment for pelvic floor disorders can include medications, botulinum toxin, surgery, physical therapy, and biofeedback. Pelvic floor muscle training for pelvic floor disorders aims to enhance strength, speed, and/or endurance or coordination of voluntary anal sphincter and pelvic floor muscle contractions. Biofeedback therapy builds on physical therapy by incorporating the use of equipment to record or amplify activities of the body and feed the information back to the patients. Biofeedback has demonstrated efficacy in the treatment of chronic constipation with dyssynergic defecation, fecal incontinence, and low anterior resection syndrome. Evidence for the use of biofeedback in levator ani syndrome is conflicting. In comparing biofeedback to pelvic floor muscle training alone, studies suggest that biofeedback is superior therapy.

Anorectal conditions that affect defecation can include structural, neurological, and functional disorders. Functional defecatory disorders including fecal incontinence, anorectal pain syndromes (levator ani syndrome [LAS], proctalgia fugax), and constipation attributable to pelvic floor dyssynergia can affect up to 25% of the pediatric and adult population with significant impact on quality of life and substantial healthcare costs. ¹

The diagnosis of functional defecatory disorders is based on objective criteria obtained through the use of anorectal physiology testing such as anorectal manometry and electromyography (EMG) as well as defecography, performed either under fluoroscopic or magnetic resonance imaging. Treatment often involves multiple providers across medical and surgical specialties and may include medications, botulinum toxin, sacral nerve neuromodulation, surgery, as well as physical therapy and biofeedback therapy. ¹ Due to its favorable safety profile, biofeedback has been increasingly used in the treatment of functional defecatory disorders, though its precise role and efficacy remain poorly defined. ^{1 2}

Pelvic floor muscle therapy (PFMT) and biofeedback are administered under the care of a specialized nurse or physiotherapist. PFMT teaches a series of contractions and relaxations of pelvic floor muscles and external anal sphincter, with the goal of maximizing strength and improving coordination of contractions. ³ Biofeedback builds upon exercises by providing visual and/or auditory cues to a patient about a physiologic process (i.e., contraction and relaxation of a muscle). This feedback can be used to identify disordered function, and then used in conjunction with training techniques (i.e., pelvic floor exercises) to learn how to control or change the disorder. ⁴ In this article, we aim to elucidate the components of biofeedback and define its role in the treatment of functional defecatory disorders.

Biofeedback Technique

Biofeedback is a therapy in which equipment is used to record or amplify, and then feed back to the patient, the activities of the body. ² The physiologic process of contraction and relaxation of a muscle is converted to a visual or auditory signal that is then fed back to the patient, with a goal of learning from the feedback to control the disordered function. ⁴ While its mechanism of action is not fully understood, enhanced rectal propulsive forces, improved anal and pelvic floor relaxation, and improved sensory thresholds are thought to contribute to improvement in symptoms. ¹ Biofeedback techniques include rectal sensitivity training, strength training, and coordination training. Protocols vary among centers; however, in general, the practitioner and patient must first understand the anorectal dysfunction and its relevance prior to starting treatment.

Biofeedback therapy is labor intensive and is typically administered by a trained nurse or physiotherapist in the clinic setting. However, given the limited number of treatment centers and importance of patient compliance for success, there is a desire for home-based, self-training programs to make biofeedback more accessible. ^{1 5} Home biofeedback focuses on training patients on use of a dual sensor probe that is inserted into the rectum and provides feedback directly to the patient. A 2018 study by Rao et al provided patients a training schedule for home therapy followed by interval clinic assessments. ⁵ Home biofeedback was found to have similar efficacy in the treatment of constipation secondary to dyssynergic defecation with decreased cost and increased patient satisfaction.

Biofeedback Components

Rectal sensitivity training utilizes a rectal balloon that is gradually distended with air or water until the patient reports the first sensation of rectal filling. Various thresholds are determined and then repeated reinflations performed to teach the patient to feel distention at progressively lower volumes. This would be useful in the situation of urge incontinence, in which a patient can detect stool at a lower threshold and have more opportunity to find a toilet or use anal squeeze as well as teach them to tolerate progressively larger volumes. ²

Strength training provides the patient with anal sphincter pressure or activity, teaching anal sphincter exercises, and gives feedback on performance and progress. ² EMG electrodes, manometric surveys, intra-anal EMG, or anal ultrasound can assist. In anal EMG, via intra-anal or perianal probes, it records and averages the activity of a large number of muscle cells that provides information on the contraction strength of the underlying muscles. ⁴ The patient can hear or see a signal instructing to squeeze, enhancing strength, and endurance. A session might start with a patient being shown anal manometry or EMG recordings to understand their anal function. With this information, they are then taught to relax their pelvic floor and anal muscles during straining. ⁴ With improvement in learned relaxation, visual and auditory feedbacks are gradually withdrawn. ⁴

Coordination training is a three-balloon system in which a distended balloon sits in the rectum and the second and third small pressure recording balloons are in the upper and lower anal canal. With increasing distention of the balloon, it assesses sensory threshold, urge sensation, and maximum tolerated volume. ^{2 3} Patients with decreased rectal sensitivity can train to distinguish and respond to small volumes of distention while patients with rectal hypersensitivity can train to tolerate larger volumes by means of progressive distention and urge resistance. ³ The aim is to improve sensitivity to smaller rectal volumes and teach the patient to counteract a possible anal relaxation due to the rectoanal inhibitory reflex by voluntary anal squeeze, allowing the resting pressure to return to a baseline level, preventing incontinence. ^{2 3}

Disorders Treated with Biofeedback

Fecal incontinence is defined by the involuntary loss of stool or gas over greater than a month long time period by a patient who previously had control. ⁶ While many studies evaluating the community prevalence of fecal incontinence are hampered by bias, representative studies show a prevalence of 8 to 15%, ^{7 8} though only a minority of these patients seek medical attention. ⁹ Causes of fecal incontinence include obstetric or other trauma, congenital abnormalities of the anal sphincter complex or pelvic floor muscles, loose stool, local pathology, weakness of pelvic floor muscles due to structural or neurological injuries, as well as functional fecal incontinence which is not explained by structural or biochemical abnormalities. ^{2 10 11} Patients with diabetes can develop fecal incontinence, thought to be due to neurogenic dysfunction of the gastrointestinal tract, possibly affecting the function of the internal and external sphincter. ¹² There are deficits in ability to perceive rectal filling (hyposensitivity) versus inability to delay defecation (hypersensitivity or urge fecal incontinence). ¹¹ First-line treatment includes patient education, dietary modification, medications, and, in patients with preserved voluntary sphincter contraction, biofeedback. ¹³

LAS is a vague, dull ache, or pressure sensation high in the rectum, which can be worse with sitting or lying down. It can last for hours to days. It is thought to be a highly likely diagnosis if the patient is tender on palpation of the levator ani muscles. ¹⁴ The pathophysiology of LAS is unclear but commonly thought to be due to chronic tension or spasm of striated pelvic floor muscles, ¹⁴ and associated with increased anal canal resting pressures. ¹ Prevalence is estimated to be ∼6.6% of adults and is higher in women, and patients aged between 30 and 60 years. ¹⁴ A recent study suggested that 85% of patients with LAS have dyssynergic defecation. ¹ Treatment aims at reducing tension in the levator ani muscles including digital massage, sitz baths, muscle relaxants, electrogalvanic stimulation, and biofeedback. ¹⁰

Proctalgia fugax is a severe, sudden, but short (seconds to minutes) anal pain that is infrequent in nature. Prevalence is reported from 8 to 18% and treatment is typically reserved for patients that have more frequent attacks. Treatment includes salbutamol inhalation, clonidine, or amylnitrite. ¹⁰

Chronic constipation is formally diagnosed based on the Rome IV criteria related to decreased stool frequency and difficulties with defecation. ⁶ Constipation is common, affecting up to 30% of the western population. ¹⁵ The etiology of functional constipation may have components of slow transit and/or obstructed defecation. Obstructed defecation syndrome may, in turn, be attributable to anismus or pelvic organ prolapse. Anismus, or inability to relax the pelvic floor muscles during defecation, is often used interchangeably with pelvic floor dyssynergia. First-line therapy includes fiber-fluid supplementation and osmotic laxatives. ¹⁵

Pelvic floor dyssynergia , or anismus, is constipation due to paradoxical contraction and an inability to relax pelvic floor muscles during defecation without any identifiable neurologic or anatomical defect. ^{4 10 16} Anismus may further be characterized into four types based on ability to generate pushing force and sphincter contraction. ⁶ It is present in 25 to 50% of patients evaluated for chronic constipation. ^{1 10} Assessment for anismus may include manometry, EMG, or defecography. On manometry, there is evidence of paradoxical increment in anal pressure on straining while defecography will show failure of anorectal angle to become more oblique on straining and impaired evacuation of contrast material. ⁴ Treatment includes biofeedback training and simulating defecation. ¹⁰

Low anterior resection syndrome (LARS) affects up to 80 to 90% of patients after low anterior resection. ^{17 18} Symptoms include a postoperative change in bowel habits including fecal incontinence, urgency, and frequent bowel movements; however, patients may have either or both fecal incontinence or constipation. ¹⁷ Studies have found that risk factors for the development of severe LARS include radiotherapy, distance from tumor lower margin to anal verge, distance from anastomotic site to anal verge, and history of diverting ileostomy. ^{17 18} The etiology is unclear, but it is likely multifactorial including a decreased rectal reservoir, denervation of the left colon, and trauma to the internal and external anal sphincter. There is no standard therapy for LARS, although several therapies have been investigated including pelvic floor rehabilitation (PFMT, biofeedback), medical treatment (serotonin receptor antagonists), irrigation, probiotics, and surgery (sacral nerve stimulation and percutaneous tibial nerve stimulation). ^{17 18} Specifically, a systematic review of pelvic floor rehabilitation found it was effective for improving continence, stool frequency, and quality of life. ¹⁸ The optimal population for pelvic floor rehabilitation after surgery remains undefined. ¹⁸

Efficacy of Biofeedback

Pelvic floor dyssynergia : The goals of PFMT combined with biofeedback include teaching patients about disordered defecation, coordinating increased intra-abdominal pressure with pelvic floor muscle relaxation during evacuation, practicing simulated defecation, and providing sensory retraining in regard to rectal filling. ¹⁹ There are variable results of the use of biofeedback on pelvic floor dyssynergia. ^{1 19} In uncontrolled studies, success with biofeedback has ranged from 18 to 100%. ⁴ This is due to heterogeneity of studies, nonrandomization, various treatment protocols, and the variety of outcomes studied. However, in a position paper in 2015 by the American Neurogastroenterology and Motility Society (ANMS) and the European Society of Neurogastroenterology and Motility (ESNM), biofeedback is recommended for short- and long-term treatment of constipation with dyssynergic defecation based on level I, grade A evidence. ¹

Randomized controlled trials have shown that biofeedback is more effective than sham treatment, laxatives, dietary modifications, and diazepam in the treatment of dyssynergic defecation. ²⁰ A randomized controlled trial by Chiarioni et al compared biofeedback to polyethylene glycol in patients with pelvic floor dyssynergia with respect to treatment satisfaction, stool frequency, laxative use, straining frequency, sense of incomplete evacuation, and feeling of blocked defecation. ¹⁶ The biofeedback group showed major improvement in 80% of patients compared with 22% in the laxative group ( p  < 0.001) with sustained improvement noted at 24 months. There were greater reductions in straining, sensations of incomplete evacuation and anorectal blockage, use of enemas and suppositories, and abdominal pain in the biofeedback treatment group. While digital facilitation of defecation portended treatment failure, no physiologic measures specifically corresponded to treatment success. A meta-analysis of seven randomized controlled trials comparing biofeedback to nonbiofeedback treatments (3 studies) or different biofeedback modalities (4 studies) demonstrated a sixfold increase in treatment success. ²¹ On review of seven randomized controlled trials by ANMS-ESNM, characteristics of patients that had success included greater willingness to participate, higher resting anal sphincter pressure, and prolonged balloon expulsion time. ¹ However, evidence does not support the use of biofeedback for patients with constipation in the absence of dyssynergic defecation (i.e., rectal prolapse, rectocele, rectal mucosal intussusception), and there is no evidence that patients with slow transit constipation will respond to biofeedback. ^{1 19}

Fecal incontinence : Studies suggest that biofeedback can reduce incontinence symptoms in two-thirds of patients. ²² The goals of biofeedback for fecal incontinence include improving strength and isolation of pelvic floor muscles, improving the ability to sense weak distention of the rectum and contract pelvic floor muscles in response, and improving the ability to tolerate larger rectal distention without subsequent uncontrollable urge sensations. ^{1 19} Patients with reduced rectal sensation can improve rectal sensation and shorten the time between rectal distention and contraction of the external anal sphincter with biofeedback. As they are without risk or cost, pelvic floor exercises should always be recommended to patients with fecal incontinence; however, their efficacy in combination with biofeedback or electronic stimulation is unknown. ¹ The ANMS-ESNM position paper recommended short- and long-term use of biofeedback for fecal incontinence based on level II grade B evidence, although randomized controlled trials showed inconsistent results. ¹ Biofeedback was recommended for those who have tried and failed conservative medical treatment (i.e., antidiarrheals, fiber supplements) provided that they have adequate cognitive ability and motivation to participate in therapy. ¹ Similarly, the American Society of Colon and Rectal Surgeons (ASCRS) clinical practice guidelines strongly recommend biofeedback for fecal incontinence based on moderate quality evidence. ¹³

In a seminal study by Wald and Tunuguntla in the New England Journal of Medicine, they evaluated a biofeedback program for diabetic patients with fecal incontinence with a secondary aim of better understanding the etiology of diabetic fecal incontinence. ¹² Therapy included rectal sensory conditioning and external-sphincter conditioning. Among study participants, they found that an impairment of conscious rectal sensation is strongly associated with diabetic incontinence as well as absence of phasic contraction of the external anal sphincter in response to rectal distention. Their results also suggested that biofeedback improved bowel control in these patients. A 2019 study by Vaghar evaluated patients with fecal incontinence and found that biofeedback improved continence in patients with anal sphincter abnormalities as well as patients with without structural abnormalities. ²³ On the other hand, Bols et al looked at biofeedback as an add-on therapy to PFMT in adults with fecal incontinence finding no evidence of an improvement with the addition of biofeedback to PFMT. ³ However, the authors did note possible benefits of biofeedback including control of urgency, external anal sphincter function as well as subjective rating of improvement and lifestyle adaptations. Methodological differences in randomized controlled trials likely contribute to the varied results in the literature, yet the most robust of the randomized trials comparing PFMT to biofeedback, which included only patients with two or more episodes of fecal incontinence per week who have failed conservative management showed a sustained benefit with biofeedback at 12 months. ²⁴ Thus, while further studies are certainly needed to better define the role of biofeedback, its use in fecal incontinence is well supported by the literature and professional society recommendations.

LAS : In the ANMS-ESNM position paper, they found level II grade B evidence for biofeedback use in the short term with LAS with dyssynergic defecation. ¹ Indications for biofeedback in patients with LAS should include those who have failed standard therapy (antispasmodics, muscle relaxants), have an absence of structural or inflammatory causes, and have tenderness of the levator ani muscles on digital rectal exam. ¹

The literature evaluating the use of biofeedback in LAS has been limited to small, uncontrolled studies with variable treatment protocols producing success rates ranging from 35 to 88%. ²⁵ However, Chiarioni et al performed a randomized study, which compared biofeedback, electrogalvanic stimulation, and digital massage. ¹⁴ The biofeedback regimen involved five training sessions. Patients were taught more effective straining techniques, and then were taught relaxation techniques using an EMG probe and biofeedback. Lastly, patients practiced defecating an air-filled balloon. Counseling followed these sessions. This was compared with electrogalvanic stimulation and digital massage and sitz baths. Outcomes assessed pain relief at 3, 6, 12 months, as well as stool frequency. This study showed that 59.6% of patients treated with biofeedback reported adequate relief compared with 32.7% of patients with emergency general surgery and 28.3% of patients who received digital massage. Patients most likely to have success with biofeedback included patients with tenderness on palpation of the levator ani muscles and those with an inability to evacuate a 50-mL water-filled balloon.

LARS : Given that the primary symptom of LARS is fecal incontinence, biofeedback is supported as a treatment option. ¹⁷ Rectal balloon therapy can improve rectal sensitivity for patients with LARS. A 2014 systematic review looked at PFMT, biofeedback, and rectal balloon therapy for patients with LARS. ¹⁸ This review found that four of five studies showed significant improvement in continence after pelvic floor rehabilitation, while one study showed that patients who started biofeedback after 18 months postoperatively showed improvement in fecal incontinence versus those who started it earlier than 18 months after surgery. Two other studies showed significant improvement in continence, number of bowel movements, and anal manometry concluding that biofeedback is one of the best treatment choices for LARS. ¹⁷

Alternative and Adjunct Treatments

PFMT is a well-established therapy for urinary incontinence but is less studied for fecal incontinence. Yet, PFMT is generally recommended for patients with fecal incontinence. ^{2 19} Research has gone as far as to recommend that all patients after low anterior resection or sphincter preserving surgery should be taught and recommended pelvic floor muscle training (Kegel home exercises) prior to discharge. ¹⁷ Leakage associated with fecal incontinence is improved via PFMT through exercises that target structural support, timing, and strengthen automatic contractions. ¹⁷ The anorectal angle, which is maintained by the puborectalis muscle in continuity with the external anal sphincter, is believed to have an important role in fecal continence as its normal values increase at rest. ⁶ Exercises are designed to enhance strength, speed, endurance, or coordination of voluntary anal sphincter contraction via systematic training with repeated voluntary contractions of the pelvic floor muscles and external anal sphincter, practiced in different starting positions. ^{2 3 18} Regimens vary by type, number of repetitions, intensity, length of time to perform the exercises, etc., and patients may be treated with a single broad regimen versus an individualized exercise program. There is no consensus among professionals on the best exercise program. ² A study by Ussing et al aimed to compare supervised PFMT in combination with conservative treatment versus attention-controlled massage. ²⁶ They used a PFMT regimen of six treatments, each 45 minutes in which patients were taught pelvic floor contractions verbally and by vaginal and rectal examination. They utilized EMG biofeedback to enhance awareness, strength, and endurance. They also created a home regimen of 3 sets of 10 pelvic floor muscle contractions held for 10 seconds then 2 sets of 3 contractions held for 30 seconds as a progressive overload. They found that PFMT in combination with conservative treatment should be offered as first-line treatment for adults with fecal incontinence.

PFMT versus Biofeedback : A study in 2003 by Norton et al aimed to study biofeedback versus attention control in patients with fecal incontinence. ²⁷ They found no significant improvement in symptoms in patients who underwent pelvic floor exercise training or biofeedback versus the control. Thus, this study recommended conservative care for patients with fecal incontinence. However, studies since then have suggested that biofeedback is useful therapy in both patients with fecal incontinence and dyssynergic defecation as noted above. Other studies suggest biofeedback as a superior therapy compared with patient education and pelvic floor exercises alone. ²⁴ An observational study by Parker et al evaluating the efficacy of biofeedback for patients with either fecal incontinence or chronic constipation showed results consistent with previous studies that biofeedback therapy for either fecal incontinence or dyssynergic defecation was successful in 76% of patients. ²⁰ In a study by Rao et al, patients were randomized to standard therapy, which included physical therapy, sham therapy, and biofeedback for the treatment of dyssynergic defecation. ²⁸ The physical therapy regimen included education from a nurse therapist regarding different postural and diaphragmatic breathing techniques in addition to other education, laxatives, fiber and fluid intake, and toilet training. This study showed that biofeedback significantly improved bowel function (including subjective satisfaction with bowel function and decreased/discontinued use of digital maneuvers for defecation) when compared with sham and standard therapy. ²⁸ A study by Heymen et al, compared biofeedback to two other groups using diazepam or placebo with standard care that included pelvic floor exercises, dietary and medication management, and patient education. ²⁴ After 3 months, more patients in the biofeedback arm reported adequate relief of constipation. Patients also reported improvement with unassisted bowel movements and fewer laxative-assisted bowel movements. Biofeedback was shown to impact pelvic floor muscle relaxation during defecation when reviewed on EMG activity. Overall, patients in the biofeedback arm had greater improvement in quality of life and satisfaction with bowel function when compared with the control groups ( Table 1 ).

Table 1. Comparison between pelvic floor muscle training and biofeedback therapy.

Pelvic floor muscle training and physical therapy	Biofeedback therapy
Exercises focus on improving voluntary anal sphincter contractions via improvements in:  –Strength  –Speed  –Endurance  –Coordination	Actions of the patient's body are recorded and observed by the patient to provide information to educate the patient and provide guidance on how to improve disordered function. Techniques include:  –Rectal sensitivity training  –Strength training  –Coordination training
Evidence for use in patients with:  –Fecal incontinence  –Low anterior resection syndrome  Also consider for patients with  –Pelvic floor dyssynergia/anismus  –Levator ani syndrome	Evidence for use in patients with  –Pelvic floor dyssynergia/anismus  –Fecal incontinence  Also consider for patients with:  –Levator ani syndrome  –Low anterior resection syndrome

Botulinum toxin : There is evidence within uncontrolled studies that injections into the anal sphincter may improve symptoms, and radiographic parameters in patients with disorder defecation. ¹⁹ Certainly, more robust trials and randomized controlled studies are needed to better understand the impact of botulinum toxin injection in patients with pelvic floor dysfunction.

Surgery : Sacral neuromodulation is primarily used for the treatment of urinary and fecal incontinence. Regarding fecal incontinence, the ASCRS clinical practice guidelines suggest that sacral neuromodulation may be considered for those with or without sphincter defects based on moderate quality evidence including several randomized trials. ¹³ Sphincteroplasty may also be considered in patients with external sphincter defects, though as few as 10% sustain a benefit in continence at 5 years. ¹³ When specifically considering patients with fecal incontinence due to LARS, there was a comparable treatment success with sacral nerve neuromodulation. ¹⁷ Furthermore, additional studies have found that sacral neuromodulation was effective for all symptoms (constipation and incontinence type) related to LARS. ¹⁷

Data are less robust for the use of sacral neuromodulation in those with constipation. However, 10 small studies in adults were reviewed to show that test stimulation was successful in 42 to 100% of patients. Of those who progressed on to permanent sacral nerve stimulation implantation, 87% showed an improvement in symptoms at 28 months. ²⁹ Stratification of these results suggests that the benefit is more likely in patients with slow transit constipation. Further studies are needed to better define the role of sacral neuromodulation in the treatment of constipation.