Cardiovascular autonomic control in Becker muscular dystrophy.

Although autonomic symptoms are not prominent in dystrophinopathies, a reduced vagal activity and an enhanced sympathetic tone have been found in Duchenne muscular dystrophy. Twenty patients with Becker muscular dystrophy (BMD) were investigated by a battery of six cardiovascular autonomic tests (beat-to-beat variability during quiet breathing and deep breathing, heart rate responses to Valsalva maneuver and standing, blood pressure responses to standing and sustained handgrip) and power spectral analysis (PSA) of heart rate variability. Although 11 patients revealed abnormal findings at some cardiovascular tests, none of them had a definite autonomic damage, as indicated by two or more abnormal tests. The mean results of the single tests did not differ from normal controls, except for the beat-to-beat variability during quiet breathing, which was significantly higher in BMD (p<0.05). Such finding was confirmed by a significantly higher total variance (p<0.05), indicating an increased parasympathetic activity. Spectral components were not significantly different from normal controls. PSA values were not influenced by age, functional ability score or presence of heart abnormalities. Our data suggest that autonomic involvement does not represent a major finding in BMD.