Muscle metabolism in patients with polymyositis simultaneously evaluated by using 31P-magnetic resonance spectroscopy and near-infrared spectroscopy

Abstract

Simultaneous measurements of muscle energy metabolism using (31)P-magnetic resonance spectroscopy ((31)P-MRS) and the kinetics of muscular oxygen metabolism using near-infrared spectroscopy (NIRS) were conducted in polymyositis (PM) patients. The subjects were 12 PM patients (age 45 +/- 12 years) and 12 normal controls (age 41 +/- 12 years). The muscle phosphocreatine (PCr) index and intracellular pH (pHi) were determined with (31)P-MRS and the changes in intramuscular oxygenated (oxy-Hb), deoxygenated (deoxy-Hb), and total haemoglobin (total Hb) were evaluated with NIRS . The pHi and PCr index before steroid therapy in PM patients were significantly lower during exercise than in normal controls, and their recovery was statistically significantly delayed compared with the controls. The pattern of changes in NIRS over time before steroid therapy in PM patients differed from that in normal controls. There were smaller changes in deoxy-Hb and oxy-Hb during exercise, and total Hb decreased during exercise. In contrast, the kinetics of muscular metabolism after steroid therapy showed changes similar to those seen in normal controls. Simultaneous (31)P-MRS and NIRS measurements to determine the kinetics of muscular metabolism are expected to be useful as a noninvasive approach for the evaluation of treatment effects in PM patients.

Near‐infrared spectroscopy during exercise and recovery in children with juvenile dermatomyositis

“…The results of a recent study in adult patients with polymyositis correspond to the findings of this study. In that adult study, total Hb concentration during gripping exercise was decreased compared with rest in the patients, whereas no such decrease was seen in the healthy subjects 34. The similarity of those results with the current results is of interest, because microvascular disturbances in muscle tissue are believed to be present in patients with polymyositis, much like in children with JDM.…”

Idiopathic inflammatory myopathies evaluated by near-infrared spectroscopy

“…These data are in line with previous observations showing a similar NIRS profile during exercise in PM patients treated with steroids as compared with healthy controls. 27 In PM, the focal increase of capillary density, due to vascular neo-formation induced by acute inflammation, may compensate for the overall loss of capillaries in areas of extensive segmental muscle necrosis. 28 A possible effect of immunosuppressive drugs on blood flow partly contributing to the NIRS profile of PM patients cannot be excluded.…”

New Insights into the Benefits of Exercise for Muscle Health in Patients with Idiopathic Inflammatory Myositis

“…Both mitochondrial and capillary functionality are a prerequisite for aerobic metabolic capacity within skeletal muscle and are directly related to endurance exercise performance [25–28]. Several signs of metabolic dysfunctions have been recorded in patients with established PM and DM, including low levels of stored phosphocreatine and ATP in muscle tissue with decreased fatigue resistance and with fewer aerobic slow-twitch type I muscle fibers [29–32]. Abnormalities in the aerobic energy metabolism found in patients with PM/DM include mitochondrial and capillary pathology [33–37].…”