Muscle changes in rheumatoid arthritis. A review of the literature with a study of 100 cases.

Muscle changes were studied in biopsy material obtained from 100 patients suffering from classical rheumatoid arthritis. The abnormalities consisted of denervation atrophy of type II muscle fibres, degenerative changes in the sarcoplasm including presence of nemaline rods, and changes within the interstitium: namely perivascular nodular myositis, lymphocytic accumulations, different stages of vasculitis and abnormalities within the intramuscular nerves and muscle spindles. The muscles examined were always severely affected. It is considered that the simultaneous presence of these abnormalities is suggestive of rheumatoid arthritis. The importance of histochemical studies is emphasized. The literature concerning muscle changes in rheumatoid arthritis is reviewed.