Association Between Malignant Hyperthermia and Severe, Chronic Muscle Pain

Abstract

The purpose of this study is to examine the relationship between anesthetic-induced malignant hyperthermia (MH) and severe, generalized, and persistent muscle pain. We have performed the caffeine-halothane contracture test (CHCT) (3% halothane-induced contractures, caffeine-specific concentrations [CSCs], and 2 mM caffeine-induced contractures) on 34 healthy volunteer controls, 114 patients who have had known or suspected malignant hyperthermic (MH) reactions, and 143 patients who have had severe and persistent muscle pain that has prevented full-time work. Serum creatine kinase (CK) levels, 3% halothane contractures, and 2 mM caffeine contractures were substantially greater and CSCs were significantly smaller in the MH and muscle pain (MP) patients than in the control patients. There were no significant differences in these parameters between the MH and the MP patients except that CK levels were greater in the MP than in the MH patients. There seem to be at least three possible scenarios for the etiology of MP. The first is that MP patients are simply MH genotypes who have not yet had an MH reaction. They possess the MH gene, and their symptoms are triggered by environmental factors such as excessive exercise, extreme heat or cold, infection, or chemicals in the workplace. The second is that MP individuals are actually chronic fatigue immune dysfunction syndrome (CFIDS) patients. It may be that muscle changes occur in CFIDS patients that mimic MH, at least so far as the CHCT is concerned. The third possibility is that the MP patients have some third, as yet unidentified, condition that is different from both MH and CFIDS. We have shown that a cohort of chronic muscle pain patients possess an organic muscle defect as evidenced by abnormal CHCTs even though the microscopic appearance of their muscles was normal and in spite of a lack of objective physical abnormalities. This defect is probably similar to MH, but whether it is identical to MH has not been shown by this study.