Valley sign in Becker muscular dystrophy and outliers of Duchenne and Becker muscular dystrophy

Valley sign has been described in patients with Duchenne muscular dystrophy (DMD). As there are genetic and clinical similarities between DMD and Becker muscular dystrophy (BMD), this clinical sign is evaluated in this study in BMD and DMD/BMD outliers. To evaluate the sign, 28 patients with Becker muscular dystrophy (BMD), 8 DMD/BMD outliers and 44 age-matched male controls with other neuromuscular diseases were studied. The sign was examined after asking patients to abduct their arms to about 90° with hands directed upwards; the muscle bulk over the back of the shoulders was observed. The sign was considered positive if the infraspinatus and deltoid muscles were enlarged and between these two muscles, the muscles forming the posterior axillary fold were wasted as if there were a valley between the two mounts. Twenty-five BMD patients and 7 DMD/BMD outliers had positive valley sign. However, it was less remarkable in comparison to DMD. It was absent in all the 44 controls. It was concluded that the presence of valley sign may help in differentiating BMD from other progressive neuromuscular disorders of that age group.

Keywords
Becker muscular dystrophy (BMD), clinical sign, valley sign, muscle hypertrophy, muscle wasting, dystrophin gene, muscular dystrophy