Diagnostic evaluation of persistent weakness. Examination reveals one of seven patterns of weakness. The pattern or weakness in combination with the laboratory evaluation leads to a diagnosis. CK, creatinine kinase; DM, dermatomyositis; FSHD, facioscapulohumeral dystrophy; IBM, inclusion body myositis; MG, myasthenia gravis; OPMD, oculopharyngeal muscular dystrophy; PM, polymyositis.