[Atypical course of malignant hyperthermia]

Area of Science:

• Anesthesiology
• Pharmacology
• Medical Genetics

Background:

• Malignant hyperthermia (MH) is a rare, life-threatening pharmacogenetic disorder of skeletal muscle.
• Susceptibility to MH is often suspected based on clinical history of adverse reactions to general anesthesia.
• Dantrolene sodium is a muscle relaxant used prophylactically and therapeutically for MH episodes.

Observation:

• A 40-year-old male with a history suggestive of MH susceptibility underwent traumatologic surgery.
• Prophylactic oral dantrolene sodium was administered prior to anesthesia.
• Anesthesia was uneventful, but 10 hours post-surgery, the patient developed fever and elevated creatine phosphokinase (CPK).

Findings:

• Prophylactic dantrolene sodium appeared to prevent an intraoperative MH crisis.
• A delayed hyperthermic episode and elevated CPK levels were observed postoperatively, suggesting a possible subclinical or atypical MH reaction.
• The patient's postoperative course was otherwise uneventful, and he was discharged after 9 days.

Implications:

• This case highlights the potential for delayed or atypical reactions even with prophylactic dantrolene treatment in MH-susceptible individuals.
• Monitoring for MH-related complications should extend into the postoperative period.
• Further research into the pharmacokinetics and pharmacodynamics of prophylactic dantrolene in MH-susceptible patients is warranted.