Effect of Cortisone on the Structure and Strength of Skeletal Muscle: A Correlative Electron Microscopic and Isometric Tension Study

MUSCLE weakness, a prominent feature in Cushing's syndrome whether primary or secondary, was described in roughly half of Cushing's original cases.¹ Müllen² also described proximal muscle weakness in six patients with Cushing's syndrome; in several it was an early symptom. More recently, a myopathy has been observed in some patients on prolonged adrenocortical therapy. Perkoff³ reported seven patients who developed weakness, especially of proximal leg muscles, during steroid therapy of blood dyscrasias. Byers⁴ noted myopathy in five out of 250 children on steroids for rheumatic fever. Steroids given for polyarteritis, asthma, scleroderma, lupus erythematosus, rheumatoid arthritis, and as replacement therapy following hypophysectomy also have resulted in myopathy.^5-9 It has been thought that the weakness was not due to the basic disease. Serum potassium levels were normal. The incidence of this complication is said to be greater with fluorinated steroids. Ellis¹⁰ and Glaser¹¹