Malignant hyperthermia (MH) is a life-threatening pharmacogenomic disorder triggered by certain anesthetic agents (e.g., halothane) or depolarizing muscle relaxants like succinylcholine. These agents cause uncontrolled calcium release in skeletal muscles, leading to hyperthermia, rigidity, metabolic acidosis, rhabdomyolysis, and cardiac arrhythmias.
Key Features:
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Onset:
- Occurs most commonly during anesthesia in the operating room but may also manifest in the early postoperative period.
- Initial signs include masseter spasm, tachycardia, and tachypnea.
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Trigger Agents:
- Volatile anesthetics and depolarizing muscle relaxants.
- Prior tolerance does not guarantee future safety.
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Inheritance and Risk Factors:
- Autosomal dominant inheritance.
- Commonly associated with RYR1 and CACNA1S mutations.
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Associated Disorders:
- Central core disease, King-Denborough syndrome, and multiminicore myopathy.
- Rare associations include nemaline myopathy, Schwartz–Jampel syndrome, and STAC3 myopathy.