PReS-FINAL-2011: Preliminary validation of a new hybrid measure of muscle strength for juvenile dermatomyositis

Introduction Juvenile dermatomyositis (JDM) is a multisystem vasculopathic disease characterized by muscle inflammation that causes symmetrical muscle weakness. Assessment of muscle strength is, therefore, a fundamental component of the clinical evaluation of children with JDM. This assessment is traditionally made using the 8-muscle Manual Muscle Testing (MMT) and the Childhood Myositis Assessment Scale (CMAS). However, the MMT does not cover all muscles or muscle groups affected in JDM, namely abdominal muscles. Although the CMAS is more comprehensive than the MMT, it is lengthy and, therefore, may not be feasible in a busy clinical setting or when a physical therapist is not available.