Duchenne muscular dystrophy (DMD) patients may have to be more alert about their chances of life-threatening constipation and they should monitor their intestinal transport vigilantly as they get older because they appear to have markedly disturbed gastrointestinal motor functions, according to a recent study. Gastrointestinal problems are not well-studied in the context of DMD, which the University of Zurich-based research team identified as a critical knowledge gap.
The study, “Gastrointestinal Dysfunction in Patients with Duchenne Muscular Dystrophy,” was published in the scientific journal PLOS ONE.
“The current study is the first comprehensive quantitative assessment of the gastrointestinal transit in its entire length in Duchenne muscular dystrophy patients. Progressive disease was associated with swallowing impairment, collection of intestinal air and chronic constipation, which so far has not been appropriately appreciated in scientific studies,” the researchers wrote.
The team followed 33 patients with DMD and asked them to provide information regarding age, eating habits and gastrointestinal symptoms in an attempt to systematically check for subjective and objective gastrointestinal disturbances. Two parameters were evaluated: gastric emptying half time (T1/2) and oro-cecal transit time (OCTT) by eating specific isotope-supplemented meals. Additionally, colonic transit time (CTT) was measured by abdominal radiography.
The median T1/2 was 187 minutes, the OCTT was 6.3 hours, both substantially longer than that of healthy subjects, reported in previous studies. The median CTT was 60 hours even though laxatives also were implemented. These results indicate there is an increase in the prevalence of gastrointestinal problems in DMD patients.
Researchers noted that T1/2 and OCTT did not correlate with common symptoms as they stand by the Gastroparesis Cardinal Symptom Index (GCSI), and CTT was not correlated with symptoms of constipation according to the ROME III criteria.
“We found that symptoms of impaired gastrointestinal function were not significantly correlated with objective measures of impaired gastrointestinal transport, suggesting that patients may not perceive potentially dangerous constipation requiring therapeutic measures. The impaired gastrointestinal function may further complicate the care of older DMD patients who already suffer from progressive impairment due to general loss of muscular strength, respiratory and cardiac failure,” the research team wrote.
Taken together, these data, along with some from mouse models, point towards potential explanations for the observed differences between DMD patients and healthy individuals. Decreased capabilities of voluntary straining due to muscle weakness and reduced availability of intestinal NO (nitric oxide) might be some of the factors to blame for the measured increase in gastrointestinal transit time. Another explanation is linked to DMD patients’ problematic posture which hinders gastric emptying.
“These novel data showing impaired gastrointestinal function, but a lack of association between symptoms and objective assessments, are clinically important because they may help to improve the care of DMD patients by highlighting the impaired gastrointestinal transit as a therapeutic target that has the potential to prevent life-threatening complications. These aspects become even more important with the increasing life expectancy of DMD patients,” the researchers concluded.