Muscular strength as an index of response to therapy in childhood dermatomyositis.

Dermatomyositis, an inflammatory disease of unknown etiology, causes diffuse symmetrical weakness and atrophy, muscular pain and tenderness, induration of muscles, and the tendency to develop contractures. The disease may follow a prolonged course which can best be managed with steroids and regulation of physical activity if there is an objective criterion for determining the extent of clinical involvement. In 6 children with dermatomyositis, quantitative muscular strength was compared with clinical evaluation of the state of the disease, serum enzyme levels, and other laboratory measures of systemic inflammation. Quantitative evaluation of ankle plantar flexor strength by the method of Beasley or handgrip force by the method of Mundale indicated that muscular strength provided a better criterion for the clinical status of the patient than any of the other laboratory tests studied. In dermatomyositis, the inflammation is equally great in distal and proximal muscles when tested quantitatively. These tests, when used together with enzyme levels and clinical evaluation, permit more effective management of dermatomyositis in children.