Gastrointestinal Problems Encountered With PD

Gastrointestinal Problems Encountered With PD

Managing Gastrointestinal Problems 
in Patients with Parkinson's 
Disease

Bodily functions such as swallowing and defecating, which we take so much for granted, are actually very complex neurologically, requiring the precise coordination of multiple muscles, some contracting and some relaxing. These functions are often impaired in patients with Parkinson's disease (PD), who have trouble with muscular coordination in general.PD patients are particularly bothered by drooling, dysphagia (difficulty swallowing), nausea, delayed gastric emptying, and constipation.

Recently, neurologist Ronald Pfeiffer offered some ideas for helping PD patients.One of the most visible symptoms of PD is drooling, which affects 80% to 90% of patients. Drooling is due to the accumulation of saliva, not the overproduction of saliva. The PD patient actually produces less saliva than normal people but swallows less frequently. Anticholinergic drugs -- benztropine (Cogentin/Merck) and trihexyphenidyl (Artane/Lederle) -- are often prescribed to "dry up" excess saliva, but this produces a sticky saliva that is even more difficult to swallow. According to Pfeiffer, a better approach is to chew gum or suck hard candy during the day, or at least during social occasions.

The act of chewing converts swallowing to a more conscious action that gives the patient more control.Dysphagia occurs in more than 50% of PD patients, primarily because the tongue, like other muscles in the PD patient, is slower and less coordinated. The patient has trouble getting food to the back of the throat where it can be moved down the esophagus. The patient must swallow several times to get a mouthful down, and thus it takes longer to eat. Aspiration is common because the glottis only partially covers the trachea. According to Pfeiffer, special swallowing techniques (bending forward "looking at the plate") can help.

Sometimes adjusting the antiparkinson medications can help as well. Nausea may be a side effect of antiparkinson medication, but it may also be due to delayed gastric emptying. Prolonged retention of food in the stomach can cause anorexia, nausea, vomiting, and possibly erratic absorption of levodopa- carbidopa (Sinemet), leading to variability in drug response.

The major drug approved for promoting gastric emptying, metoclopramide (Reglan/Robins), is contraindicated in PD patients because it aggravates symptoms. A new "prokinetic" agent that has recently become available in the United States, cisapride (Propulsid/Janssen), safely accelerates gastric emptying. Approved for treating nocturnal heartburn in patients with gastroesophageal reflux disease, cisapride acts by restoring the normal physiologic antireflux mechanism.Cisapride also accelerates colonic transit, and studies involving PD patients in particular have shown that the drug is effective for slow-transit constipation.

Slow-transit constipation is a common problem in PD patients (30% to 50% prevalence). The slower the transit is, the longer fecal material remains in the colon, the more fluid is extracted, the harder the stool becomes, and the greater the risk of impaction is. To improve the flow, attention must be paid to fiber and fluid intake. Patients should be counseled to increase their intake of fiber-rich foods (vegetables, whole grains) or to take fiber supplements (Metamucil) and increase fluid intake. Stool softeners may be useful but are no substitute for fiber. Laxatives, especially those that irritate and potentially damage bowel nerves and muscles, should be avoided. Lactulose and sorbitol may also be helpful, and suppositories and enemas may sometimes be necessary.

The act of defecation is a highly complex function that is often disturbed and inefficient in PD patients. Approximately two thirds of PD patients have trouble evacuating feces, and in some patients the problem is so severe that it dominates their daily functions. In such patients, laxatives are usually not helpful. Adjusting PD medication may sometimes help.

Investigators are currently evaluating injections of apomorphine or botulinum toxin to relax rectal muscles that are contracting inappropriately. "Our understanding of GI dysfunction in PD patients has increased significantly in recent years," said Pfeiffer. Now this increased understanding needs to be translated into improved patient care.