Evolution of gastric electrical features and gastric emptying in children with Duchenne and Becker muscular dystrophy

OBJECTIVES: Although muscular dystrophy (MD) affects primarily striated muscles, smooth muscle cells of the gastrointestinal tract may also be involved. We recorded gastric electrical activity and gastric emptying time (GET) in children with MD at initial presentation and at 3-yr follow-up in order to detect gastric motor abnormalities and study their evolution along the clinical course. METHODS: Twenty children with MD (median age: 4.6 yr; range age: 3-7 yr) were investigated by means of ultrasonography, for measuring GET, and by electrogastrography (EGG); 70 children served as controls. RESULTS: Ten patients had Duchenne muscular dystrophy (DMD) and 10 Becker muscular dystrophy (BMD). GET was significantly more delayed in MD patients (DMD, median: 195 min; range 150-260 min; BMD, median: 197 min; range: 150-250 min) than in controls (median: 150 min; 110-180 min; p < 0.05); it markedly worsened at the follow-up in DMD (median: 270 min; range 170-310 min; p < 0.001 vs controls) but not in BMD patients (median: 205 min; 155-275 min; p < 0.05 vs DMD). Baseline EGG showed a significantly lower prevalence of normal rhythm and significantly higher prevalence of dysrhythmias in both groups of patients as compared to controls (% of normal rhythm: DMD 66.7 +/- 8.2, BMB 67.2 +/- 11.5, controls 85.3 +/- 7.2, p < 0.001; % of tachygastria: DMD 28.4 +/- 8.0, BMB 29.8 +/- 12.3, controls 10.6 +/- 5.1, p < 0.001; % of dominant frequency instability coefficient: DMD 36.1 +/- 6.0, BMB 33.2 +/- 2.9, controls 17.9 +/- 7.1, p < 0.001); furthermore, no difference in fed-to-fasting ratio of the dominant EGG power was found between the two groups and controls (DMD 2.84 +/- 1.27, BMB 2.82 +/- 0.98, controls 3.04 +/- 0.85, ns). However, at the follow-up no significant change in the prevalence of normal rhythm and dysrhythmias occurred in both groups (ns vs baseline values), whereas only DMD patients showed a marked reduction in fed-to-fasting power ratio (0.78 +/- 0.59; p < 0.001 vs controls and BMD; p < 0.05 vs baseline), which correlated with the progressive neuromuscular weakness occurring in DMD subjects (r, 0.75; p < 0.001). CONCLUSIONS: In children with MD, there is an early abnormality in gastric motility that is due to deranged regulatory mechanisms, whereas contractile activity of smooth muscle cells seems to be preserved. At the follow-up, DMD patients exhibited a progressive failure in neuromuscular function, which was accompanied by a gastric motility derangement with worsening in GET and in EGG features suggesting an altered function of gastric smooth muscle cells.