Malignant hyperthermia testing in probands without adverse anesthetic reaction

Area of Science:

• Medical Genetics
• Pharmacology
• Neuromuscular Disorders

Background:

• Malignant hyperthermia (MH) is primarily known as an anesthetic-triggered reaction.
• However, MH-like symptoms can occur in various non-anesthetic-related disorders.
• Investigating these non-anesthetic cases is crucial for understanding MH spectrum.

Purpose of the Study:

• To investigate reasons for MH testing referrals in non-anesthetic cases.
• To assess the phenotype of patients with non-anesthetic MH-like reactions.
• To evaluate the efficacy of oral dantrolene in non-anesthetic probands with positive caffeine-halothane contracture tests (CHCT).

Main Methods:

• Retrospective analysis of probands referred for MH testing without anesthetic reactions.
• Selection of patients who underwent the caffeine-halothane contracture test (CHCT).
• Analysis of clinical details, creatine kinase (CK) levels, and response to oral dantrolene.

Main Results:

• 64% of patients referred for non-anesthetic indications tested positive for CHCT.
• Positive CHCTs were associated with high CK, exercise intolerance, chronic fatigue, and muscle weakness.
• Oral dantrolene improved musculoskeletal symptoms in 82% of CHCT-positive patients, with response linked to CK levels.

Conclusions:

• A positive CHCT may indicate disorders beyond anesthetic sensitivity.
• Muscle symptoms can manifest in individuals with positive CHCTs without anesthetic triggers.
• Oral dantrolene shows potential therapeutic benefit for these non-anesthetic related symptoms.