Idiopathic inflammatory myopathies evaluated by near infrared spectroscopy

Introduction: We evaluated whether near infrared spectroscopy (NIRS) can determine the metabolic patterns of dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM). Methods: We enrolled 10 consecutive patients affected by DM, 11 by PM, 9 by IBM, and 3 groups of healthy controls. We measured changes in oxygenated and deoxygenated hemoglobin/myoglobin in the extensor digitorum communis during venous and arterial occlusion testing (VOT) and post-occlusion hyperemia. Results: DM showed lower oxygen consumption (P=0.04) during VOT and reduced oxygen supply after VOT (P=0.04) versus controls. IBM showed higher oxygen consumption (P=0.04) during VOT and higher oxygen supply after VOT (P=0.03) than controls. DM showed reduced oxidative metabolism compared with IBM (P=0.001) and impaired ability to supply oxygen compared with PM (P= 0.03) and IBM (P= 0.001). Discussion: NIRS differentiates samples of DM and IBM patients from controls, but it cannot distinguish PM patients from a sample of healthy subjects. © 2014 Wiley Periodicals, Inc.