Gastrointestinal System - DM1


  • Because the smooth, as well as the skeletal, muscles are involved in DM1, dysfunction along the entire gastrointestinal (GI) tract is common in this disorder. Weakness and myotonia of the smooth muscles occurs.

  • Among the common problems are dysphagia, aspiration, abdominal pain and bloating, especially after eating, slow gastric emptying, gastroesophageal reflux, constipation, diarrhea and “irritable bowel” symptoms, gallstones, dilated colon, which can result in fecal impaction, megacolon and even perforation of the bowel; and anal incontinence. GI symptoms are not only surprisingly common in DM1 but can also be the initial or dominant clinical characteristic. However, these symptoms may be underestimated or ignored.

  • Gastrointestinal dysmotility that frequently results in pseudo-obstruction and can lead to aspiration.


  • Problems with chewing or swallowing, drooling, gastroesophageal reflux, bloating, abdominal pain, frequency and characteristics of bowel movements, diarrhea and fecal incontinence. Careful history should be taken to differentiate oropharyngeal dysphagia from esophageal dysphagia. Esophageal dysphagia sometimes causes chest pain due to acid reflux from the stomach. Food aspiration and resultant pneumonia are a leading cause of death in DM1 patients.

  • Involuntary weight loss or weight gain; dysphonia or dysphagia that may indicate pharyngeal muscle weakness; frequent cough and recurrent broncho-pneumopathies that may indicate aspiration; abdominal pain on palpation (generally or in the area of the gallbladder); and abdominal bloating during routine physical exams.


  • Discuss the following tests with your doctor:

    • Physical exams such as a rectal exam for constipation, including anal sphincter spasm and dyssynergic defecation for symptomatic individuals.

    • Acute abdominal symptoms:

      • Pseudo-obstruction in addition to mechanical obstruction.

      • If acute bowel obstruction is considered, CT enterography or MR enterography can distinguish pseudo-obstruction from the surgical emergency of true (mechanical) obstruction.

      • Foer acute abdominal pain, cholecystitis should be excluded.

      • Individuals without mechanical obstruction should be treated conservatively for pseudoobstruction and/or cholelithiasis.

      • Abdominal x-ray to evaluate abnormal bowel gas or stool, or free abdominal air.

      • Abnormal amounts of hydrogen with the glucose breath test. It is abnormal for individuals with lactose intolerance and bacterial overgrowth in their intestine.

    • Signs of abnormal bowel gas or stool, or free abdominal air in an abdominal x-ray study.

    • Dyssynergic movements, oral and/or pharyngeal weakness, or aspiration using a standard swallowing study or a modified barium swallow evaluation with consultation by a speech therapist.

    • Abnormalities in stomach, small bowel, large bowel or gallbladder anatomy with abdominal ultrasound or magnetic resonance imaging (MRI).

    • Lower esophageal function and reflux, gastric emptying, and small bowel anatomy and function using barium upper GI radiographic evaluation.

    • Weakness or disordered contraction of esophagus, gastroesophageal sphincter, stomach, small bowel, rectum or anal sphincter using manometry or functional motility testing in patients who do not respond to therapy.

    • Abnormal structure or function of pharynx, esophagus, stomach, small intestine or large intestine using endoscopy.

    • Cholestasis or hepatic involvement using specific blood tests (serum alkaline phosphatase and bilirubin elevation correlate with cholestasis in DM). Measure GGT levels because elevations of AST and ALT may be due to the skeletal muscle disease from DM1. Cholecystectomy is one of the most common reasons for general anesthesia and neuromuscular blocking agents; extreme care should be taken if general anesthesia is necessary to perform this procedure.

    • Follow screening guidelines for colon cancer that apply to the general population; epidemiological studies have shown a higher rate of malignancy for this cancer in DM1.


  • Early referral for consultation by a gastroenterologist should be considered for refractory symptoms. Care should be taken for those tests requiring anesthesia or sedation.

  • Non-pharmacologic treatments for gastrointestinal symptoms:

    • High-fiber diet (15-20 grams per day) for diarrhea or constipation as first response. Increased fiber intake should be undertaken with increased water intake, with the exception of drinks that are high in caffeine and fructose.

    • Nutrition consultation for dysphagia, weight loss or weight gain, to assess nutritional adequacy.

    • Dysphagia therapy referral, including compensatory strategies and dietary modifications, for oral pharyngeal dysphagia.

  • Potential pharmacologic treatment for gastrointestinal symptoms:

    • Loperamide (Imodium), with care, for diarrhea.

    • Gentle laxatives (see below) for constipation. Oils should be avoided. If not response to the first- or second-line recommendations below, a referral to a gastrointestinal specialist for anal manometry should be considered.

    • First-line therapy recommendations: polyethylene glycol (Miralax), senna (Ex-Lax, Senokot), docusate (Colace) or lactulose (Cholac).

    • Second-line therapy recommendations: bisacodyl (Dulcolax, Correctol), lubiprostone (Amitiza) or linaclotide (Linzess).

    • Metoclopramide (Reglan) may be used to reduce the symptoms of gastroparesis, pseudo-obstruction and gastric reflux. Long-term use is not recommended because this drug can cause tardive dyskinesia.

    • If bacterial overgrowth is found on breath testing, treating with antibiotics may reduce diarrhea.

  • Enteral feeding (tube feeding) may be required in for severe dysphagia, for example, dysphagia that causes weight loss or recurring pneumonia. Tube feeding is not commonly needed. Nutrition via gastrostomy tube is acceptable for hospice care.

  • Probiotic regimens (many are over the counter) may be tried under a physicians supervision.