Atypical symptoms of malignant hyperthermia: A rare causative mutation in the RYR1 gene

Malignant hyperthermia (MH) is an autosomal dominant genetic condition of the skeletal muscle triggered by inhaled general anesthetic agents or succinylcholine and associated with a hypermetabolic state and skeletal muscle rigidity. Tachycardia, increased carbon dioxide production, hypercarbia, hyperthermia, acidosis, hyperkalemia, cardiac arrhythmias, muscle rigidity, and rhabdomyolysis are common symptoms of MH. As the progression of the syndrome could be rapid or less evident, even experienced physicians have difficulty in diagnosing MH, which can lead to delays in treatment and increased mortality. We report a rare case of a 36-year-old man, who underwent open reduction and internal fixation of the left clavicle after inhaled anesthetics. The patient developed dyspnea, hypotension, unremitting hyperthermia, tachycardia, and elevated serum myoglobin, and finally died of pyemia and disseminated intravascular coagulation. We reviewed the process of disease development, summarized the steps of diagnosis, and improved genetic testing. Exome sequencing revealed a new mutation c.8519G>A (p.arg2840 GLN) in the RYR1 gene that could be associated with MH. The gene mutation was also found in his daughter's genetic test. This case emphasized the importance of the awareness of MH and its atypical clinical symptoms. The presence of dyspnea, hypotension, unremitting hyperthermia, tachycardia, and raised myoglobin in serum might further strengthen the clinical diagnosis of suspected MH.