Management of Suspected Malignant Hyperthermia With Dantrolene: Clinical Insights From 2 Case Reports in a Single-Center Experience.

Introduction: Malignant hyperthermia (MH) is a fatal hypermetabolic reaction of skeletal muscle, triggered by exposure to volatile anesthetic agents or depolarizing muscle relaxants. It typically exhibits hypercarbia, muscle rigidity, tachycardia, and hyperthermia. Diagnosis is often confirmed through a muscle biopsy for the in vitro contracture test or by identifying pathogenic genetic variants. Case Presentation: We report 2 cases of suspected MH. The first case involved a 4-year-old female (20 kg) undergoing adenotonsillectomy, and the second involved a 13-year-old female (56 kg) who underwent pedicle screw fixation surgery. Both patients had unremarkable medical histories. During maintenance of general anesthesia with sevoflurane, they developed clinical signs highly suggestive of MH-10 minutes after exposure in the first case and 120 minutes after exposure in the second case. Both cases were managed with dantrolene and supportive care. In the first case, dantrolene was administered 4 hours after the initial signs, by which time significant rhabdomyolysis had already developed. In the second case, early administration within 10 minutes was associated with a much milder degree of rhabdomyolysis. Conclusion: Early recognition of symptoms and accurate differentiation of MH from similar conditions are essential for favorable outcomes. Prompt administration of dantrolene at the first sign of an MH reaction is critical for effective management.