Irritable Bowel Syndrome

(Spastic Colon)

A motility disorder of unknown cause characterized by abdominal pain, diarrhea, or constipation.

New-onset irritable bowel syndrome (IBS) is uncommon in elderly persons. The incidence and prevalence in the elderly are not well defined. IBS occurs in about 10 to 20% of persons in the USA, of whom about 10 to 33% seek medical attention. In the USA, more women are diagnosed with this disorder than men (2:1 to 3:1 ratio).

Pathophysiology

Disturbances in intestinal motility may result from physical or psychologic stimuli, although no specific stimulus or response pattern is characteristic. Patients may have an increased motility response in the small and large intestine and more symptoms with various stimuli (ie, food, pentagastrin, cholecystokinin, rectal distention, physical or psychologic stress) when compared with control populations. Patients with IBS also appear to have a lower sensation threshold and pain tolerance to intestinal distention than non-IBS patients.

Foods that increase intestinal gas may exacerbate complaints. Some patients are intolerant of wheat, dairy products, coffee, tea, or citrus fruits, but other studies have not found consistent intolerance to specific foods. Antibiotics, -blockers, bronchodilators, cardiac drugs, diuretics, and opioids disrupt GI processes and may produce IBS symptoms. Tobacco and alcohol may exacerbate symptoms by altering intestinal motility. Tobacco may also contribute to increased intestinal gas.

Many patients with IBS describe acute episodes of stress preceding the onset of bowel symptoms. In addition, about half of patients have noted that stress can worsen their symptoms. Yet, most patients with IBS do not differ psychologically from the general population.

Diagnosis

Elderly patients with IBS usually have a long history of bowel dysfunction, sometimes beginning in childhood or adolescence. However, if the symptoms have changed, an evaluation should be conducted to eliminate the possibility of concurrent pathologic processes.

The Rome criteria for IBS include continuous or recurrent abdominal pain or discomfort for >= 3 months that is relieved with defecation. Defecation is irregular or varies >= 25% of the time and is characterized by two or more of the following: altered stool frequency, altered stool consistency (hard or loose/watery stool), altered stool passage (straining or urgency, feeling of incomplete evacuation), passage of mucus, and bloating or feeling of abdominal distention.

No distinct physical findings occur, although the abdomen may be tender. Laboratory findings are usually normal. However, in the elderly it is prudent to obtain a complete blood count, electrolytes (with vomiting or diarrhea), ESR, urinalysis, and stool testing for blood. Stool should be examined for leukocytes, ova, and parasites and cultured when patients have diarrhea. The selection of other diagnostic tests depends on the primary symptoms (ie, diarrhea vs. constipation), chronicity and severity of symptoms, and associated clinical features. Unnecessary testing should be avoided.

Treatment

Organic disease must be excluded before symptomatic therapy is begun. No drugs have produced consistent results. The physician should educate the patient about the disorder, legitimize the patient's concern about the chronicity of the symptoms, and help the patient to adapt.

Patients with mild or infrequent symptoms tend not to visit their physician often and generally maintain normal activity levels. Foods that can exacerbate symptoms (ie, lactose, fatty foods, alcohol, artificial sweeteners, beans) should be eliminated from the diet, and symptoms should be monitored.

Patients with moderate symptoms that intermittently disrupt activity should record the frequency, duration, and severity of their symptoms and associated factors in a diary for 1 to 2 weeks. Based on this information, the physician may suggest dietary and behavioral modifications. Severe symptoms that impair daily functioning may be treated with drugs. If pain is predominant, anticholinergic (antispasmodic) drugs are most frequently used to decrease intestinal motility. However, these drugs pose a risk to the elderly because of their anticholinergic properties and should be used only when absolutely essential and with close monitoring. Hyoscyamine (0.125 mg po tid to qid before meals) or dicyclomine (10 to 20 mg qid) appears to be most effective for patients with postprandial episodes of pain. If diarrhea is predominant, antidiarrheal drugs can be recommended. Loperamide (2 to 4 mg bid to tid) increases intestinal transit time, facilitates water and ion absorption, and strengthens rectal sphincter tone. If constipation is predominant, fiber (20 to 25 g/day) can be given through diet or as a supplemental bulking agent.

Behavioral interventions (relaxation techniques, hypnosis, therapy) also assist motivated patients with moderate to severe symptoms, especially if the symptoms are associated with stressors.

A small subset of patients with severe symptoms and continuous refractory abdominal pain that does not correlate with intestinal physiology commonly have psychiatric comorbidity. These patients often cannot acknowledge the psychologic contribution to the illness, believe that a serious illness is being overlooked, and often have unrealistic expectations that a cure can be found. They are typically unresponsive to traditional therapy and require a gastroenterologist with expertise in psychoactive drugs and pain relief.