| Malignant Hyperthermia (MH) is a disorder where susceptible individuals show a hypermetabolic reaction to anaesthetics. A subset of MH-susceptible (MHS) patients experience muscle weakness, fatigue and exercise intolerance. Additionally, some individuals with heat or exercise-induced rhabdomyolysis (MH-like reactions) show MH susceptibility. The purpose of this study was to assess skeletal muscle metabolism and exercise performance, to define metabolic phenotypes in MH patients. Phosphorous magnetic resonance spectroscopy (31P-MRS) and blood oxygen level-dependent fMRI were performed to evaluate skeletal muscle metabolism. Participants then performed exercise tests to assess aerobic capacity, anaerobic capacity, and muscle strength. 31P-MRS revealed MH patients, particularly those with severe muscle symptoms, had significantly lower oxidative phosphorylation ATP production than healthy controls, accompanied by impaired aerobic and anaerobic capacity. Impairments were similar between patients with MH-like reaction (MHS-L) and MHS. Chronic mitochondrial damage is proposed as the pathophysiological mechanism for metabolic and functional impairment in MHS and MHS-L patients. |
