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Bowel dysfunction is common in multiple sclerosis (MS) and is reported by approximately 60 percent of those with the disease. The mechanism of defecation is similar to that of micturition, involving afferent fibers entering the S3-5 segments of the spinal cord. Distention of the rectal walls provides the stimulus for defecation, resulting in contraction of the rectal muscles and relaxation of the intemal anal sphincter. Abdominal muscle contraction (controlled by the T6-12 spinal cord segments) facil- itates evacuation, and voluntary relaxation of the external anal sphincter completes the process. Demyelination along one or more points of the central nervous system (CNS) component of this process leads to diffi- culties with bowel function. Both constipation and involuntary bowel movements may occur, with constipation being by far the more frequent complaint.
Causes and management of constipation
A number of factors may cause or exacerbate constipation:
- Demyelination along the CNS pathway responsible for defecation
- Weakened abdominal muscles
- Medications used to treat concomitant problems
- Inadequate fluid intake
- Insufficient dietary bulk
- Decreased mobility
- Pubococcygeal spasticity
Constipation can be reduced by a stepwise process beginning with a search for possible iatrogenic factors (side effects of medications), assessment for the presence of neurogenic bladder dysfunction, then progressing through basic natural measures such as fluid and dietary intake, to mechanical techniques such as digital stimulation and enemas, and finally moving into medical interventions if necessary (see algorithm). Sufficient time (up to 4 weeks) should be allowed for each of the regimens discussed before moving to the next step. This will permit a true evaluation of effectiveness. More extreme surgical procedures are indicated in rare cases and should be addressed by a gastroenterologist.
An overall assessment of past and current bowel function should be done when changes in bowel function are first noted and at least annually in the absence of obvious deviations. This should include a history of bowel patterns, symptoms, and interventions, both successful and unsuccessful. Physical evaluation is also necessary and should include abdominal palpation and rectal exam with assessment of sphincter tone.
Assessment needs to further address more MS-specific issues such as medications that affect bowel function and the potential impact of urinary tract dysfunction.
Measures to evaluate and manage constipation
Medication Review
Several categories of medication can precipitate or exacerbate constipation, and a review of medications should be the first step in evaluating constipation. These include:
- Antihypertensives
- Analgesics/narcotics
- Tricyclic antidepressants
- Antacids
- Iron supplements
- Anticholinergics
- Sedatives/ tranquilizers
- Some antibiotics
- Diuretics
Drugs used to control a hyperactive detrusor muscle are most likely to cause a problem. Medications such as propantheline bromide and imipramine, which often successfully manage bladder storage dysfunction, can contribute to constipation, requiring a careful trial and error approach. Substitution or adjustment of dosage must be done one item at a time, allowing a sufficient interim period to evaluate the impact of each intervention.
Bladder management and fluid intake
The next step is to investigate whether urinary symptoms are also present. If both bowel and bladder dysfunction are identified, bladder problems should be addressed first in most cases. Many patients practice fluid restriction, sometimes to an extreme degree, in an attempt to control distressing urinary symptoms such as frequency, urgency, and incontinence. Once urinary dysfunction is no longer a major problem, it will be possible to work with the patient to increase fluid intake in order to prevent desiccated stool, which is difficult to move along the gastrointestinal (GI) tract and to evacuate.
Early intervention and education
Fluid Intake
The generally recommended fluid intake is 2000 ml/ day. One way to individualize the volume of optimum fluid intake is to add 500 ml to the guide- lines used to estimate needs of the general public (I), or 40 mI/kg of body weight + 500 ml. For those patients without bladder problems, the necessity for sufficient fluid intake can be addressed at the onset.
Diet-Fiber, Bulk Formers, and Concentrated Sugar Preparations
In addition to fluids, prune juice and/ or dried fruits are the easiest, and often most effective, dietary measures. Sufficient dietary fiber is also essential, with no less than 15 grams of fiber needed daily. Fiber intake should be increased gradually and from a wide variety of sources. The subcommittee on the 10th edition of the Recommended Daily Allowances (1) advises that whenever possible fiber be added to the diet through the consumption of fruits, vegetables, legumes, and whole-grain cereals, rather than by using fiber concentrates. Symptoms of intolerance should be monitored, with a reduction in fiber as needed (2) .If a high-fiber diet cannot be achieved, bulk supplements such as Metamucil®, FiberCon®, Perdiem®, or Citrucel® can be used. One or two glasses of clear fluid (e.g., water, apple juice, broth, tea) should be taken with these agents for full benefit. Metamucil is also available as wafers that are acceptable to some patients who dislike the liquid. Patients need to be aware that bloating and gas from a high-fiber diet or supplements may require 2 to 3 weeks to subside.
Bulk laxatives also suppress alternating constipation and diarrhea, which is common in the general population on an American diet. The diarrhea side of this may lead to incontinence, particularly in MS patients with impaired mobility. Use of fiber as a treatment for diarrhea or a preventive measure protecting from diarrhea should be emphasized.
Liquid sugar concentrates are another natural intervention. They act by drawing water into the intestine, thereby softening the stool. Preparations include Sorbitol®, Lactulose®, and Golytel®. Side effects are rare, and these agents are useful for long-term management (3).
Physical Activity and Other Measures
Decreased physical activity due to MS-related limitations also contributes to constipation; peristalsis becomes sluggish, and weakened abdominal muscles restrict the "bearing down" phenomenon that usually promotes evacuation. Recommendations to address these obstacles are fairly straightforward:
- Initiate and maintain a regular program of physical exercise. In addition to its effects on constipation, exercise improves fitness and quality of life (4).
- Schedule a regular time for evacuation that takes advantage of the beneficial stimulus of the gastrocolic reflex; 20 to 30 minutes after breakfast is the optimal time. A simple activity to compensate for weakened abdominal muscles is the Valsalva maneuver (bearing down after taking and holding a deep breath). Bending forward to compress abdominal contents can enhance this effort, as can abdominal massage.
- Education about the nonnal process of fecal elimination, the limitations imposed by MS, and compensatory interventions is essential to promote adherence to whatever plan is developed.
- Integrate the plan into the person's lifestyle and cultural mores.
Oral Agents
A variety of oral agents are available to facilitate the passage of stool through the GI tract. The most frequently used stool softeners are Colace® (dioctyl sodium sulfasuccinate-DSS, 100 mg), Surfak® (40 mg) and generic docusate (240 mg) .These are effective for mild constipation. Mild laxatives, such as Milk of Magnesia® or Peri-Colace®, can be effective as a next step. Harsh laxatives such as bisacodyl should be reserved for occasional one-time use and not used as part of an on-going bowel program.
Suppositories
Either a mild glycerin suppository to lubricate the stool or a stronger bisacodyl suppository to chemically stimulate the rectum to evacuate stool is effective when the rectum is full, but expulsion is impaired by inadequate emptying ability. The patient or caregiver must be instructed to insert the suppository against the rectal wall and not into the stool. Patience is also needed; glycerin may need 15 minutes or more to act, and bisacodyl may require 45 minutes. When significant pubococcygeal spasticity is present, the suppository also facilitates sufficient effacement for evacuation. If the lubricant or chemical stimulant properties of these agents are not needed, digital stimulation may suffice.
Enemas
The enema most useful for a regular bowel program is the mini-enema Ther- Evac®, Ther-Evac Plus®, or Colace® microenema, which contains a small amount of solution in a suppository-like delivery system. Fleet® or tap water enemas should be reserved for episodic use, unless atonic bowel is present in severely disabled individuals. Frequent use of tap water enemas can deplete sodium; saline enemas should be used when these are a frequent option.
Involuntary bowel incontinence: causes and management
Involuntary bowel or fecal incontinence can result from several pathologic situations: sphincter dysfunction, constipation with rectal overload and overflow, and/ or diminished rectal sensation. Fecal incontinence is often associated with constipation ( 5) .Constipation distends the rectum and interferes with compliance. Therefore, much of the management of involuntary bowel is similar to that for constipation. However, there are factors to consider first when fecal incontinence is reported (see algorithm).
Dietary irritants such as caffeine and alcohol should be considered as contributing factors, and eliminated when present. In addition, medications that reduce spasticity in striated muscle may be contributing to the problem. These primarily include baclofen and tizanidine, both used frequently in MS, and their dose or scheduling may need to be adjusted.
Anticholinergic drugs can be helpful when a hyperactive bowel is the underlying cause of incontinence. Since these drugs also affect bladder function, careful initiation and titration are needed, and post-void residual urine volume should be monitored to avoid precipitating urinary retention.
Diarrhea may lead to bowel incontinence because it is difficult for the sphincter to contain liquid stool. The cause of the diarrhea needs to be identified. Impaction is a common component, with viral and bacterial causes also possible. Since diarrhea can be extremely debilitating, this condition needs to be vigorously addressed for general health considerations as well as continence.
Summary
Most instances of constipation and involuntary bowel in MS can be managed with systematic persistence on the part of both the patient and the clinician. It is important to remember that bowel dysfunction, like other MS symptoms, can change over time, and that referral to a gastroenterologist is appropriate when conservative measures have been unsuccessful.
References
- National Research Council, Recommended Dietary Allowances, Subcommittee on the lOth Edition of the RDAs, Food and Nutrition Board, Commission on Life Sciences, National Academy Press, Washington, DC, 1989.
- Consortium for Spinal Cord Medicine, Paralyzed Veterans of America, Neurogenic bowel management in adults with spinal cord injury, Clinical Practice Guideline, March 1998.
- Harati D, QuinlanJ, Stiens S. Constipation and spinal cord injury: A guide to symptoms and treatment. Washington, DC: Paralyzed Veterans of America, 1992.
- Petajan J, Gappmair E, White A, Spencer M, Mino L, Hicks R Impact of aerobic training on fitness and quality of life in multiple sclerosis, Ann Neurol1996; 39:432-441.
- Goodwin R, Fowler C. Bladder, bowel and sexual dysfunction: Recent advances. In: Thompson A, Polman C, Hohlfeld R (eds.). Multiple sclerosis: Clinical challenges and controversies. London: Martin Dunitz, 1997.
Source
Reproduced with kind permission from:
van den Noort S and Holland NJ. Multiple sclerosis in clinical practice. New York: Demos, 1999: pp81-88
Available from Demos Medical Publishing
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USA. Tel +(212) 683 0072. Fax: +(212) 683 0118.
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