Idiopathic inflammatory myopathies evaluated by near infrared spectroscopy.

[inclusion body myositis]

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 can not distinguish PM patients from a sample of healthy subjects . © 2014 Wiley Periodicals , Inc .