Peripheral muscle function and pulmonary function in patients with systemic sclerosis

Abstract

Introduction: Systemic sclerosis (SS), also known as scleroderma, is a rheumatic disease, chronic in nature autoimmune, that has the characteristic fibrosis and dysfunction vascular that lead to lesions sclerotic skin and internal organs. Among them, the lung is the main responsible for the mortality in patients with SS. The manifestations of lung are varied, but the main pulmonary changes are hypertension of the pulmonary artery and pulmonary fibrosis, both caused by the proliferation of uncontrolled fibroblasts, along with the excessive release of collagen. The changes musculoskeletal are also very common in the course of the ES. The muscle involvement can be present in the form of myositis or myopathy inflammatory or non-inflammatory, having a manifestation of diverse muscle weakness, atrophy and elevation of the enzyme creatine fosfoquinase. Objectives: To evaluate the muscle function and peripheral lung in patients with SS. As specific objectives: to determine the muscular strength and endurance peripheral; to evaluate the lung function in these individuals; to evaluate the physical function and the levels of general fatigue in patients with SS; and to correlate peripheral muscle function levels with the physical function, general fatigue and lung function in this population. Methods: Were included 26 patients with age ≥18 years of female gender, with a diagnosis of SS according to the criteria of the American College of Rheumatology / European League Against Rheumatism. These patients underwent lung function tests, measurement of muscle strength of quadriceps and hamstrings through the isocinetic dynamometer, as well as a test of handgrip. They were subsequently answered the following questionnaires: the Fatigue Impact Scale (FIS), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), and Health Assessment Questionnaire Disability Index (HAQ-DI). Was also recruited a control group that was matched for anthropometric variables and physical activity level and did not present no evidence of any musculoskeletal disorder. Results: Women with SS showed significant reductions in almost all isokinetic parameters for the two angular velocities tested compared with the controls. An agonist/antagonist ratio with values <40% was observed in approximately one-third of the patients. These patients also had lower handgrip and FACIT-F values and higher FIS values than the controls. An HAQ-DI score ≥1.0 was observed in half of the sample. Significant correlations were observed between the isokinetic parameters and the handgrip, HAQ-DI, respiratory muscle strength, and forced vital capacity / diffusing capacity for carbon monoxide ratio values. Conclusion: SS patients have reduced strength and endurance as well as a muscle imbalance between the quadriceps and hamstrings. In these patients, lower muscle strength of the knee joint is associated with lower handgrip strength, lung function and physical capacity.