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Clinical Focus:

• The diagnosis is Malignant Hyperthermia (MH), a life-threatening pharmacogenetic hypermetabolic crisis triggered by volatile anesthetics or depolarizing neuromuscular blockers.

Aetiology/Cause:

• Autosomal dominant mutation in the ryanodine receptor type 1 (RYR1) gene or CACNA1S gene regulating calcium channels in skeletal muscle.
• Triggered by exposure to volatile inhalational anesthetics (e.g., Sevoflurane, Isoflurane, Desflurane) or the depolarizing muscle relaxant Succinylcholine.
• Uninhibited, massive release of calcium from the sarcoplasmic reticulum into skeletal muscle cytoplasm drives continuous muscle contraction, hypermetabolism, ATP depletion, severe heat production, and muscle cell membrane breakdown.

Clinical Features:

• Earliest and most sensitive clinical sign: rapid, unexplained rise in end-tidal CO2 (ETCO2) hypercapnia refractory to hyperventilation.
• Masseter muscle spasm (trismus) immediately following succinylcholine administration.
• Tachycardia, cardiac arrhythmias, labile blood pressure, tachypnea, and generalized muscle rigidity.
• Rapidly rising core body temperature (late sign, rising up to 1-2°C every 5 minutes), skin mottling, and diaphoresis.

Diagnosis and Investigations: