Fatigue rate index as a new measurement of external sphincter function.

PURPOSE: Assessment of sustained voluntary contraction of the external sphincter is helpful in evaluating the patient who has a defecation disorder on presentation. A new index of external sphincter function is described. METHOD: A prospective registry of patients referred for computerized anal manometry using standard protocols was reviewed. Patients were grouped by primary symptoms; those with overlapping complaints were excluded. The rate of fatigue, defined as the change in stationary squeeze over a 40-second period of voluntary contraction, was calculated by linear regression analysis. Fatigue rate index, a calculated measure of time necessary for the external sphincter to become completely fatigued, was determined to permit comparison of external sphincter fatigue in patients with different complaints. RESULTS: Twenty-six healthy volunteers (15 women; mean age, 45 years), 33 patients with a primary complaint of anal seepage (13 women; mean age, 53 years), 75 patients with gross incontinence (61 women; mean age, 53 years), and 49 patients with severe constipation (41 women; mean age, 45 years) were evaluated. Mean resting and squeeze pressures were 55 mmHg and 107 mmHg for volunteers, 37 mmHg and 97 mmHg for patients with seepage, 30 mmHg and 49 mmHg for incontinent patients, and 56 mmHg and 93 mmHg for constipated patients. Pudendal neuropathy, as evidenced by a prolonged pudendal nerve terminal motor latency (> 2.4 ms), was identified in 13 percent of volunteers, 32 percent of patients with seepage, 54 percent of incontinent patients, and 38 percent of constipated patients. Mean fatigue rate index was 3.3 minutes for volunteers, 2.3 minutes for seepage patients, 1.5 minutes for incontinent patients, and 2.8 minutes for constipated patients. Compared with volunteers and patients with seepage, the incontinent patients had a significantly shorter fatigue rate index (P < 0.05; Student's t-test), which was independent of the variations in resting pressure (P < 0.05; two-way analysis of variance). CONCLUSION: The external anal sphincter is normally subject to fatigue. Patients with worsening degrees of incontinence have a predictably lower fatigue rate index. Fatigue rate index is a simple measure of external sphincter integrity, which may be used in assessment of sphincter function and future treatment protocols.

Pudendal neuropathy is the only parameter differentiating leakage from solid stool incontinence.

PURPOSE: Fecal incontinence may occur in several forms. Although some patients are grossly incontinent, other patients experience only leakage. In patients with gross incontinence, severity can range from the mildest forms (limited to loss of control of flatus) to the most severe forms (involving loss of solid stool). This study was undertaken to determine which physiologic parameters differentiate female patients with incontinence of solid stool from patients with control of formed stool and incontinence limited to seepage. METHODS: Thirty-eight consecutive female patients with a primary complaint of seepage or solid stool incontinence were evaluated using water perfusion manometry, balloon inflation assessment of rectal sensitivity, and pudendal nerve terminal motor latency. A prospectively maintained database was used for collection of data. The findings in the two patient groups were compared with patients in a group of normal control individuals. Ages of the women in the three groups were similar. RESULTS: Both groups of patients demonstrated statistically significant (P < 0.05) decreases in rest and squeeze sphincter lengths, pressures, and pressure volumes compared with normal volunteers. The patients also had significantly more asymmetric high-pressure zones and hypersensitive rectums. No significant difference between the two groups of incontinent patients could be identified using any of these parameters. Significant differences between the groups were found in pudendal nerve function. The distal rectoanal excitatory reflex was abnormal in 58.1 percent of grossly incontinent women compared with 28.6 percent of patients with leakage (P < 0.05). The majority of patients with leakage alone (65 percent) had normal pudendal nerve terminal motor latency, whereas only 22.6 percent of women with gross fecal incontinence had normal pudendal nerve terminal motor latency bilaterally (P = 0.01). CONCLUSIONS: Normal bilateral pudendal nerve function can partially compensate for abnormal sphincter symmetry and function, permitting women with grossly abnormal parameters to maintain control of bowel movements. It remains to be seen whether, with advancing age, patients with leakage will have development of slowed pudendal nerve conduction and, if so, whether their condition will progress to gross incontinence.

Prospective comparative study of abnormal distal rectoanal excitatory reflex, pudendal nerve terminal motor latency, and single fiber density as markers of pudendal neuropathy.

PURPOSE: This study was undertaken to determine the role of abnormal distal rectoanal excitatory reflex (RAER) as a marker of pudendal neuropathy and to compare results with pudendal nerve terminal motor latency (PNTML) and single fiber density (SFD) estimation. METHODS: Fifteen female patients (mean age, 47.1 (range, 20-70) years) referred to the pelvic floor laboratory with pelvic floor disorders (fecal incontinence, 13 patients; constipation, 2 patients) were evaluated prospectively with neurophysiologic tests and balloon reflex manometry for evidence of pudendal neuropathy. RESULTS: Pudendal nerve terminal motor latency provided evidence of pudendal neuropathy in ten patients (67 percent) and was normal in five patients (33 percent). Increased SFD confirmed denervation of the external anal sphincter in 12 patients (80 percent), being normal in 3 patients (20 percent). Distal RAER was abnormal in 13 patients (87 percent) and was normal in 2 patients (13 percent). In ten patients (67 percent), the three diagnostic modalities were in complete agreement, correctly identifying neuropathy in nine patients (60 percent) and excluding nerve damage in one patient (7 percent). Distal RAER was normal despite prolonged PNTML and increased SFD in one patient (7 percent). In two patients (13 percent), distal RAER was abnormal or absent despite normal PNTML and SFD. Pudendal nerve terminal motor latency was normal in the presence of abnormal distal RAER and increased SFD on electromyography in two patients (13 percent). CONCLUSIONS: Abnormal distal RAER compares favorably with current neurophysiologic tests used to diagnose pudendal neuropathy.

Unilateral pudendal neuropathy. Impact on outcome of anal sphincter repair.

PURPOSE: Our purpose was to study the effect of unilateral pudendal neuropathy on the results of anal sphincter repair. METHOD: Fifteen female patients who underwent external sphincter repair for fecal incontinence were studied. In all instances, incontinence was the result of obstetric delivery injury. Anal manometry and neurophysiologic investigations to document sphincter defects and pudendal neuropathy were performed in all patients. Sphincter repair was performed using an overlapping suture technique. RESULTS: All patients had anterior sphincter defects. Seven patients (47 percent) had pudendal neuropathy: six (85 percent) had unilateral neuropathy, and one (15 percent) had bilateral neuropathy. Six patients (40 percent) had excellent results; three (20 percent) had good results; four (27 percent) were improved; two (13 percent) experienced no improvement after sphincter repair. All patients with excellent results had normal pudendal nerve terminal motor latency on both sides. Of the three patients with good results, one patient had unilateral pudendal neuropathy. The patients in the remaining two groups (improved and failed) had unilateral (six patients) or bilateral (one patient) pudendal neuropathy. CONCLUSION: We conclude that both pudendal nerves must be intact to achieve normal continence after sphincter repair. Patients with unilateral pudendal neuropathy are more likely to have poor than to have good postoperative function.

Can manometric parameters predict response to biofeedback therapy in fecal incontinence?

PURPOSE: Biofeedback therapy may improve fecal control in up to 50 percent to 92 percent of patients with fecal incontinence. Identification of favorable manometric parameters before biofeedback therapy may help in selection of patients suitable for such therapy. METHODS: Twenty-eight patients with fecal incontinence (idiopathic, 11; iatrogenic trauma, 8; obstetric trauma, 9) who underwent biofeedback therapy were studied to determine whether manometric parameters could predict the result of therapy. Biofeedback was given using a computer software program designed to strengthen the external anal sphincter with auditory and visual feedback. RESULTS: Thirteen patients (46.4 percent) achieved excellent results; eight patients (28.6 percent) had good results, but seven patients (24.5 percent) failed to improve after biofeedback therapy. Resting or squeeze anal canal pressure, pressure volume, sphincter length, sphincter fatigue rate, and cross-sectional asymmetry of the entire sphincter before biofeedback failed to reveal any statistically significant differences between responders and nonresponders. However, the cross-sectional asymmetry of the high-pressure zone within the sphincter at rest was greater in nonresponders than in responders (not improved, 25.8 percent; good result, 20.2 percent; excellent result, 15.4 percent; P < 0.07). This difference was even greater on squeeze (not improved, 21 percent; good result, 17.6 percent; excellent result, 13.2 percent; P < 0.04). The number of biofeedback sessions, response on bearing down, and quality of rectoanal excitatory reflex were not reliable indicators of outcome. No statistical difference was found in mean resting and squeeze pressures after biofeedback between responders and non-responders. CONCLUSIONS: Except for increased cross-sectional asymmetry in the high-pressure zone, which may be a forerunner of adverse outcome, manometric parameters before biofeedback do not predict response to biofeedback therapy. Improvement in continence may be independent of resting and squeeze pressures achieved after biofeedback therapy.

Distal rectoanal excitatory reflex: a reliable index of pudendal neuropathy?

PURPOSE: Denervation of the extrinsic anal sphincter and pudendal neuropathy are confirmed by electrophysiologic or electromyographic testing, techniques that may not be available universally and require special equipment and training. A simple manometric test that is easy to perform and complements existing studies was performed to confirm pudendal neuropathy. METHODS: Fourteen patients with excessive defecatory straining and 30 patients with idiopathic fecal incontinence were studied by electrophysiology and balloon reflex manometry. Pudendal nerve terminal motor latency (PNTML) and rectoanal excitatory reflex were evaluated for abnormalities. Results were compared with 20 controls who had no anorectal complaints and who had similar testing performed. RESULTS: In controls, PNTML was normal in all but one person. Rectoanal excitatory reflex could be elicited in all controls with either 20 or 40 ml of air. Four different types of balloon reflex responses were observed in patient groups: diminutive excitation, delayed excitation, excitation at high volume of distention only, and absent excitation. Ten patients with fecal incontinence had normal PNTML but abnormal distal excitatory reflex, 5 patients had abnormal PNTML but normal distal excitatory reflex, and 15 patients had both PNTML and excitatory reflex that were abnormal. In patients with excessive defecatory straining, results of both tests were abnormal in six patients, and eight patients had abnormal excitatory reflex but normal PNTML. CONCLUSION: Pudendal neuropathy may result in abnormalities of excitatory reflex morphology or other characteristics. Abnormal distal excitatory reflex may complement electrophysiologic findings or may serve as a suitable alternative to confirm pudendal neuropathy in centers where facilities for formal testing are not available.

State of the defunctionalized sphincter in patients undergoing ileoanal pouch anastomosis.

PURPOSE: Our aim was to determine manometric status and functional outcome of the ileoanal pouch procedure in a subset of patients with defunctionalized anal sphincters as a result of long-term fecal diversion. METHODS: The anal manometric profiles of 12 patients defunctionalized for one year or more were compared with 26 patients with nondefunctionalized anal sphincters. Functional data were obtained from the Lahey Clinic Ileoanal Pouch Registry. RESULTS: Preoperative manometric data revealed a mean resting pressure of 91.5 mmHg in the nondefunctionalized group vs. 68.7 mmHg in the defunctionalized group; mean squeezing pressure was 171.7 mmHg (nondefunctionalized group) vs. 102.3 mmHg (defunctionalized group); and squeezing pressure volume was 1,283,000 mmHg3 (nondefunctionalized group) vs. 585,000 mmHg3 (defunctionalized group). Functionally both groups had a mean of 6.1 bowel movements in a 24-hour period and could defer defecation for a mean of 2 hours. Leakage occurred in 22 percent of the defunctionalized group and 17 percent of the nondefunctionalized group (P = 0.35). CONCLUSION: Despite physiologic perturbations, the long-term, defunctionalized anal sphincter can adequately support a restorative procedure without regard to timing of pouch creation.

Computer-generated profiles of the anal canal in patients with anal fissure.

PURPOSE: The pathophysiology of anal fissure remains poorly understood. This study examines manometric findings in patients with anal fissure with use of a computer-assisted system, which helps to standardize manometric performance as well as generating longitudinal and cross-sectional profiles of the anal canal. METHODS: Water-perfused, eight-channel, computer-assisted manometry was performed on 12 patients with chronic anal fissure and compared with 12 age-matched and sex-matched controls. RESULTS: Mean maximum average resting pressure (MARP) was 120.5 mmHg in patients and 82.6 mmHg in controls (P = 0.0005). Pain was felt during manometry in six patients. In these patients, MARP was 123.2 mmHg, and, in the other six patients, MARP was 117.8 mmHg. Sphincter length was 4.72 cm, and the high pressure zone or that part of the sphincter with pressure more than 50 percent of MARP) was 2.78 cm in length. The high pressure zone/sphincter length ratio was 58 percent compared with 48 percent in controls. Longitudinal profile was bell shaped. Elevated pressures were not confined to the site of the fissure. Cross-sectional analysis showed higher anterior pressures in the distal sphincter. Ultraslow waves were seen in as many as 91 percent of patients and 73 percent of controls. However, ultraslow wave amplitude was 31 mmHg in patients and 15 mmHg in controls (P = 0.03). The rectoanal reflex was normal; overshoot was not seen. CONCLUSIONS: The primary abnormality in fissure is persistent hypertonia affecting the entire internal sphincter, unrelated to pain. Cross-sectional pressure profiles may explain the predilection of fissures to occur in the posterior midline; other factors must prevent chronic fissures from healing.

Biofeedback training is useful in fecal incontinence but disappointing in constipation.

BACKGROUND: Successful biofeedback therapy has been reported in the treatment of fecal incontinence and constipation. It is uncertain which groups of incontinent patients benefit from biofeedback, and our impression has been that biofeedback is more successful for incontinence than for constipation. PURPOSE: This study was designed to review the results of biofeedback therapy at the Lahey Clinic. METHODS: Biofeedback was performed using an eight-channel, water-perfused manometry system. Patients saw anal canal pressures as a color bar graph on a computer screen. Assessment after biofeedback was by manometry and by telephone interview with an independent researcher. RESULTS: Fifteen patients (13 women and 2 men) with incontinence underwent a mean of three (range, 1-7) biofeedback sessions. The cause was obstetric (four patients), postsurgical (five patients), and idiopathic (six patients). Complete resolution of symptoms was reported in four patients, considerable improvement in four patients, and some improvement in three patients. Manometry showed a mean increase of 15.3 (range, -3-30) mmHg in resting pressure and 35.7 (range, 13-57) mmHg in squeezing pressure after biofeedback. A successful outcome could not be predicted on the basis of cause, severity of incontinence, or initial manometry. Twelve patients (10 women and 2 men) with constipation underwent a mean of three (range, 1-14) biofeedback sessions. Each had manometric evidence of paradoxic nonrelaxing external sphincter or puborectalis muscle confirmed by defography or electromyography. All patients could be taught to relax their sphincter in response to bearing down. Despite this, only one patient reported resolution of symptoms, three patients had reduced straining, and three patients had some gain in insight. CONCLUSIONS: Biofeedback helped 73 percent of patients with fecal incontinence, and its use should be considered regardless of the cause or severity of incontinence or of results on initial manometry. In contrast, biofeedback directed at correcting paradoxic external sphincter contraction has been disappointing.