Assessment of noninvasive intra-anal electromyography to evaluate sphincter function

Normative values in anorectal manometry using microtip technology: a cohort study in 172 subjects

PURPOSE

The aims of this study were to obtain normative values in resting/squeeze pressure and surface electromyography (s-EMG) in anorectal manometry using microtip technology and to determine the relationship between objective measurable values, gender and age in a cohort with no anorectal disorders.

METHODS

One hundred seventy-two white central European subjects (106 males/66 females) were recruited prior to left colonic or upper rectal surgery and studied by anorectal rapid pull-through manometry with a microtip transducer system and endoanal s-EMG using a bipolar plug electrode. s-EMG patterns were determined as plateau, peak and decrease by a blinded co-investigator. Objective measurable sphincter pressures and s-EMG values were correlated with gender, age and s-EMG patterns.

RESULTS

Squeeze pressure, voluntary pressure as well as s-EMG amplitude and its area under the curve were significantly lower in women compared to men (p < 0.001 each), whereas resting pressure showed no gender differences. s-EMG patterns were strongly influenced by gender. Male patients showed significantly more plateau pattern whereas peak pattern was significantly more often in women. In both genders, the peak pattern was associated with significant higher squeeze pressures. In all measurements, we found considerable inter-individual variations being higher in elder patients. There was no manometric parameter correlating with age.

CONCLUSIONS

Gender is the strongest factor influencing objective measurable manometric data for healthy men and women. There are significant gender differences concerning squeeze patterns. All manometric values should be interpreted in the context of gender and of methodology used. Large prospective cohort studies matched for gender are necessary to clarify the effect of ageing on anal sphincter strength.

The evaluation of constipation

Constipation is a major medical problem in the United States, affecting 2% to 28% of the population. Individual patients may have different conceptions of what constipation is, and the findings overlap with those in other functional gastrointestinal disorders. In 1999, an international panel of experts laid out specific criteria for the diagnosis of constipation known as the Rome II criteria. When patients present with complaints of constipation, a complete history and physical examination can elicit the cause of constipation. It is imperative to rule out a malignancy or other organic causes of the patient's symptoms prior to making the diagnosis of functional constipation. Many patients' symptoms can be relieved with lifestyle and dietary modification, both of which should be implemented before other potentially unnecessary tests are performed. Functional constipation is divided into two subtypes: slow transit constipation and obstructive defecation. Because many different terms are used interchangeably to describe these subtypes of constipation, physicians need to be comfortable with the language. Slow transit constipation is due to abnormal colonic motility. The diagnosis is made with the use of a colonic transit study. We continue to use a single-capsule technique as first described in the literature, but modifications of the capsule technique as well as scintigraphic techniques are validated and can be substituted in place of the capsule. Obstructive defecation is a much more complex problem, with etiologies ranging from rare diseases such as Hirschsprung's to physiologic abnormalities such as paradoxical puborectalis contraction. To fully evaluate the patient with obstructive defecation, anorectal manometry, defecography, and electromyography should be utilized. The different techniques available for each test are fully covered in this article. When evaluating each patient with constipation, it is important to keep in mind that the disease may be specific to one subtype or a combination of both subtypes. Because it is difficult to differentiate the subtypes from the patient's history, we feel it is imperative to evaluate patients fully for both slow transit and obstructive defecation prior to any surgical intervention. Furthermore, we have described many tests that need to be applied to one's population of patients on the basis of the capabilities and expertise the institution offers.

Protocol- and therapist-related variables affecting outcomes of behavioral interventions for urinary and fecal incontinence

Biofeedback techniques used to treat urinary and fecal incontinence lack standardization. Most early protocols used a pressure device placed within the vagina or anal canal, or electromyographic (EMG) sensors in the same locations, to measure the external anal sphincter (EAS) or pelvic floor muscle (PFM) contractile function, and most early studies provided feedback from a single physiological transducer. The goal was to improve bowel and bladder control by improving EAS or PFM contractile function. Protocols that have resulted in the most consistent reductions in urinary incontinent episodes used 2 or more channels of physiological information to reinforce stable abdominal and bladder pressures concurrently with PFM contraction. For fecal incontinence, more significant treatment results were derived when protocols measured (1) patient perception of sensory cues associated with rectal distention and potential loss of stool, (2) short-latency EAS contraction when perceiving rectal distention, (3) inhibition of (extraneous muscle) activity that would increase intra-abdominal pressure during EAS contraction, and (4) reinforcement of sustained (up to 30 seconds) contractions rather than only brief 1- to 2-second contractions. Limited data support the use of surface abdominal EMG measures as indices of extraneous muscle activity associated with increased intra-abdominal pressure and anal or vaginal EMG probes to obtain measures of PFM function. Better results may also be obtained when there are at least 4 training sessions, when daily home exercises are prescribed, and when the therapist is well trained and experienced. These inferences are based for the most part on indirect evidence, and more studies are needed that compare different treatment protocols.

Fecal incontinence: evaluation and treatment

Fecal incontinence affects men and women of all ages, leading to personal disability and high financial costs. The evaluation of the patient should clarify the pathophysiology of the symptoms and provide guidance in choosing the appropriate treatment. A comprehensive history and physical examination including endoscopic assessment is able to identify the cause of most cases of fecal incontinence. If necessary, functional methods can be used to confirm the diagnosis. Patient selection for suitable treatment is most important and should be based on clinical and physiologic findings. Conservative dietary or medical treatment is often effective, when the symptoms are mild. Biofeedback therapy is effective in most patients. It has no side effects and is well tolerated. Structural damage to the anus may be repaired by surgery, like sphincter repair, the best treatment of selective sphincter defects. Neoanal sphincters and artificial sphincters are the last possibility after failed surgery and before colostomy. They are less attractive because of technical difficulties and low success rate. A multidisciplinary approach to treatment has the potential to improve the outcome for patients with fecal incontinence.

Surgical treatment of constipation and fecal incontinence

Fecal incontinence is a disabling and distressing condition. Many patients are reluctant to discuss the condition with a physician. A thorough history, good physical examination, and detailed anorectal physiologic investigations can help in the therapeutic decision-making algorithm. Patients with isolated anterior sphincter defects are candidates for overlapping repair. In the presence of unilateral or bilateral pudendal neuropathy, the patient should be counseled preoperatively regarding a [table: see text] lower anticipation of success. If the injury occurred shortly before the planned surgery and neuropathy is present, it may be prudent to wait because neuropathy sometimes can resolve within 6 to 24 months of the injury. Pudendal nerve study may help determine surgical timing. An anterior sphincter defect combined with a rectovaginal fistula can be approached by overlapping sphincter repair and a concomitant transanal advancement flap. Patients who had undergone multiple such procedures may benefit from concomitant fecal diversion at the time of repeat sphincter repair. Patients with global or multifocal sphincter injury may be candidates for a neosphincter procedure. The stimulated graciloplasty and artificial bowel sphincter are reasonable options. In the absence of the availability of these techniques or because of financial constraints, consideration could be given to bilateral gluteoplasty or unilateral or bilateral nonstimulated graciloplasty. The postanal repair still serves a role in patients with isolated decreased resting pressures with or without neuropathy or external sphincter injury with minimal degrees of incontinence. Biofeedback and the Procon device may play a role in these patients. Lastly, fecal diversion must be considered as a means of improving the quality of life because the patient can participate in the activities of daily living without the fear of fecal incontinence.

Electromyography of the external anal sphincter: comparison between needle and surface electrodes

PURPOSE

Electromyography of the external anal sphincter is frequently used when investigating patients with defecation disorders. Investigations are often performed using an invasive technique by perineal insertion of a needle or wire electrode. The aim of the present study was to investigate whether surface electromyography, with electrodes applied to the perineal skin, is a reliable method in the diagnosis of paradoxical anal sphincter reaction.

METHODS

Seventy-one patients with defecation disorders participated in the present study. They were investigated with electromyography of the external anal sphincter using surface and needle electrodes.

RESULTS

In 65 of 71 (92 percent) patients the electromyography recording showed the same result during straining using surface electrodes when compared with needle electrodes. Twenty-two of these 65 patients had paradoxical anal sphincter reaction, and 43 patients had decreased electromyography activity. In 6 of 71 (8 percent) patients the electromyography recording showed a different pattern during straining using surface electrodes when compared with needle electrodes.

CONCLUSION

The present study demonstrates a good correlation between surface electrodes applied to the perineal skin and concentric needle electrodes in the diagnosis of paradoxical anal sphincter reaction. Noninvasive electromyography recordings of the external anal sphincter are often preferred in the diagnosis of paradoxical anal sphincter reaction.

AGA technical review on anorectal testing techniques

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics Committee. Following external review, the paper was approved by the committee on May 17, 1998.

The stimulated gracilis neosphincter for fecal incontinence: a new use for an old concept

The stimulated gracilis neosphincter is a viable procedure in selected patients with fecal incontinence. The aim of this paper is to review the technique of this staged operative procedure and review the problems and complications. Stage 1 consists of the vascular "delay" of the gracilis muscle and the creation of a temporary stoma. Stage 2 consists of transposition of the muscle around the anus with implantation of the stimulator. Low-frequency electrical stimulation is applied to the muscle for 12 weeks, after which stage 3 (stoma closure) is undertaken. From March of 1993 to March of 1995, 14 patients (9 females and 5 males) with a mean age of 44 years (range 20 to 67 years) underwent the procedure. Two patients died within 1 year of the operation from unrelated causes. Two patients developed anal stenosis and required permanent stomas. Other complications noted during ascent of the learning curve included seroma, excoriation of the skin above the stimulator, transposition of the stimulator, premature battery discharge, wound infection, rupture of the gracilis tendon, fatigue during programming sessions, and electrode displacement or fibrosis from the nerve. However, 8 of the 10 eligible patients had stoma reversal; the manometric results showed an average mean squeeze pressure that increased from 43 mmHg prior to surgery to 151 mmHg after the operation (p < 0.01). Based on an objective functional questionnaire, 60 percent of the patients who could be evaluated reported improvement in continence, social interactions, and the quality of their life. In conclusion, despite a steep learning curve, the stimulated gracilis operation is a viable operation for selected patients with severe incontinence.

Electrodiagnostic evaluation of fecal incontinence

The aim of this study was to assess the utility of electrodiagnostic testing (EDT) for the evaluation of fecal incontinence (FI). Over a 5-year period, 225 patients (174 females) with FI were prospectively studied with anal manometry, anal ultrasonography, anal electromyography (AEMG), and pudendal nerve terminal motor latency (PNTML) assessment. The mean age was 60 (range 12-94) years. Causes of FI identified by clinical evaluation were obstetric injuries (45), rectal prolapse (43), iatrogenic or other trauma (42), neurologic disease (23), and idiopathic (72). EDT revealed abnormalities in 76% of patients. The incidence of pudendal neuropathy (PN) was 36% (bilateral 21%, unilateral 15%). Patients with PN were older than were those with normal PNTML (mean 71 vs. 63 years; P < 0.002). No relationship between squeeze pressure and PN could be demonstrated (P = 0.9). Reduced motor unit potential (MUP) recruitment on AEMG was present in 60% and was associated with decreased squeeze pressure (P < 0.001) and increased MUP polyphasia (P < 0.001). Concurrence of AEMG and anal ultrasonographic findings was observed in 35 of 41 patients (84%). Defects were overlooked in one study but identified by the other on three occasions, each. Moreover, 8 of 22 patients with demonstrated sphincter defects had unsuspected PN or extensive sphincter injury on AEMG that precluded sphincter repair. In conclusion, EDT proved to be a valuable tool in the evaluation and subsequent treatment of patients with FI.

Simple electromyographic biofeedback treatment for chronic pediatric constipation/encopresis: preliminary report

Pediatric constipation/encopresis is thought to be due, in part, to paradoxical constriction of the external anal sphincter (EAS) muscle during attempted defecation. This inappropriate contraction can lead to delayed, impacted, painful, and infrequent bowel movements. Standard Medical Care (SMC) involves disimpaction with enemas, followed by laxative therapy and diet modification, to maintain frequent soft stools. Using the case control method, the efficacy of SMC alone was compared with SMC plus EAS electromyographic biofeedback aimed at eliminating paradoxical contraction. Thirteen consecutive chronically constipated children received SMC plus biofeedback, and were compared with 13 age- and sex-matched children who received only SMC. Biofeedback subjects demonstrated post-treatment elimination of EAS paradoxical constriction. At 16 months follow-up parents of biofeedback children reported significantly greater improvement in constipation, encopresis, laxative use, and painful bowel movements compared to SMC.

Sonographic, manometric, and myographic evaluation of the anal sphincters morphology and function

PURPOSE

A direct comparison of anal sphincter physiology (muscle performance and anatomy-muscle thickness) has not yet been undertaken but may be of importance in patients with defecation disorders.

METHODS

We evaluated 15 healthy volunteers by means of anorectal manometry to determine pressure functions of the internal and external and sphincter. Transcutaneous electromyography was recorded to assess the electrical activity of the external anal sphincter. Thickness of the anal sphincter muscles was measured sonographically from within the anal canal with dorsal projection using a 7.5-MHz 360 degrees rectal panorama scanner.

RESULTS

It was shown that neither is the muscle thickness of the external anal sphincter during rest (6.26 +/- 1.02 mm) or during squeezing (7.40 +/- 1.39 mm) correlated to its squeeze pressure (138.8 +/- 15.2 mmHg), nor is the diameter of the internal anal sphincter (2.09 +/- 0.58 mm) correlated to its resting pressure (61.1 +/- 15.2 mmHg). Finally, the thicker the internal and sphincter muscle, the lower the electrical activity of the external anal sphincter during squeezing (r = 0.74, P < 0.001).

CONCLUSION

It is concluded that both manometry to assess sphincter function and sonography to determine sphincter morphology are important measures in the evaluation of continence function.

Pudendal neuropathy and the importance of EMG evaluation of fecal incontinence

A prospective study was undertaken to evaluate pudendal neuropathy in fecal incontinence. Fifty-two patients (38 women and 14 men) with fecal incontinence underwent manometric and electromyographic evaluation (measurement of pudendal nerve terminal motor latency [PNTML] and sphincter muscle mapping). The average age of all patients was 54 +/- 17 years. Fifty-two percent (27/52) were found to have a pudendal neuropathy (PNTML > 2.1 milliseconds). Seventeen of these 27 patients (63 percent) had a bilateral pudendal neuropathy. Patients with a pudendal neuropathy were older than those without a neuropathy (63.7 years vs. 51.9 years; P = 0.01). Women were significantly more likely than men to have a pudendal neuropathy (P = 0.03). Nine patients had an anatomic sphincter defect identified, and six of these (67 percent) had a neuropathy; 4/6 (67 percent) had a bilateral pudendal neuropathy. In the 43 patients who did not have an anatomic sphincter defect, there was no difference in resting pressure (69 mmHg vs. 60 mmHg; P = 0.4) or maximum voluntary contraction (95 mmHg vs. 86 mmHg; P = 0.5) when patients without a neuropathy were compared with those with a neuropathy. Patients with a pudendal neuropathy had a shorter sphincter length than those without a neuropathy (3.0 cm vs. 3.9 cm; P = 0.01). Bilateral pudendal neuropathy tended to occur more frequently in women (P = 0.08) and was not associated with poorer resting pressure, maximum voluntary contraction, or shorter sphincter length. We conclude that pudendal neuropathy is a common cause of fecal incontinence, particularly in older women, and frequently occurs in association with a sphincter defect. Manometric evaluation alone is not helpful in identifying the neuropathic patient. PNTMLs should be routinely measured in the evaluation of fecal incontinence.

Etiology and management of fecal incontinence

Fecal incontinence is a challenging condition of diverse etiology and devastating psychosocial impact. Multiple mechanisms may be involved in its pathophysiology, such as altered stool consistency and delivery of contents to the rectum, abnormal rectal capacity or compliance, decreased anorectal sensation, and pelvic floor or anal sphincter dysfunction. A detailed clinical history and physical examination are essential. Anorectal manometry, pudendal nerve latency studies, and electromyography are part of the standard primary evaluation. The evaluation of idiopathic fecal incontinence may require tests such as cinedefecography, spinal latencies, and anal mucosal electrosensitivity. These tests permit both objective assessment and focused therapy. Appropriate treatment options include biofeedback and sphincteroplasty. Biofeedback has resulted in 90 percent reduction in episodes of incontinence in over 60 percent of patients. Overlapping anterior sphincteroplasty has been associated with good to excellent results in 70 to 90 percent of patients. The common denominator between the medical and surgical treatment groups is the necessity of pretreatment physiologic assessment. It is the results of these tests that permit optimal therapeutic assignment. For example, pudendal nerve terminal motor latencies (PNTML) are the most important predictor factor of functional outcome. However, even the most experienced examiner's digit cannot assess PNTML. In the absence of pudendal neuropathy, sphincteroplasty is an excellent option. If neuropathy exists, however, then postanal or total pelvic floor repair remain viable surgical options for the treatment of idiopathic fecal incontinence. In the absence of an adequate sphincter muscle, encirclement procedures using synthetic materials or muscle transfer techniques might be considered. Implantation of a stimulating electrode into the gracilis neosphincter and artificial sphincter implantation are other valid alternatives. The final therapeutic option is fecal diversion. This article reviews the current status of the etiology and incidence of incontinence as well as the evaluation and treatment of this disabling condition.

The usefulness of tests in anorectal disease

Specialized tests of anorectal function are designed to complement but not to replace good clinical examination and sound professional judgement. The different methods of recording pressure changes have advantages and disadvantages. Poor correlation exists when data recorded using miniature balloons are compared with data from microtransducers. Prolonged ambulatory monitoring of anal sphincter and rectal pressure reveal that spontaneous transient episodes of sphincter relaxation are demonstrable in normal subjects. In the investigation of patients with possible traction injury to the pudendal nerve, electromyography and pudendal nerve terminal motor latency data are more precise than manometry data. Good correlation between noninvasive surface electromyography using an intra-anal plug electrode and anal manometry can be attained. Mapping of sphincter defects using concentric needle technology is reasonably accurate but distinctly painful. Dynamic defecography readily demonstrates abnormalities of the rectal wall. The division between what is normal and what is clinically relevant is rather imprecise. Comparative studies of sonographic and electromyographic mapping of sphincter defects give good correlation. Recent application of fine hooked electrodes have demonstrated periodic episodes of smooth muscle and sphincter relaxation. The saline infusion test and balloon expulsion test help to accurately quantify the difficulty patients experience in retention or evacuation, respectively. Perineometry is a simple, rapid, noninvasive method of measuring the extent of perineal descent on straining. Although reproducible, it tends to underestimate the degree of descent when compared with the radiological method but it avoids the use of ionized radiation.