[Pathological myophosphorylase reaction in malignant hyperthermia]

Area of Science:

• Biochemistry
• Pathology
• Muscle Physiology

Background:

• Malignant hyperthermia (MH) is a severe pharmacogenetic disorder of skeletal muscle.
• Triggered by volatile anesthetics and succinylcholine, MH causes hypermetabolism and muscle rigidity.
• Current diagnostic methods for MH can be invasive or lack sensitivity in post-mortem analysis.

Observation:

• The myophosphorylase enzyme reaction in muscle tissue exhibits unique, rapid changes during malignant hyperthermia.
• These changes include weakened reactions, negatively reacting fibers, and characteristic 'striated fibers' indicating hypercontraction.
• These specific pathological alterations are often missed by standard histological stains and reactions.

Findings:

• Pathological myophosphorylase reactions were consistently observed in patients and pigs with confirmed malignant hyperthermia.
• These reactions were absent in control subjects, pigs without halothane reactivity, and prior to anesthetic challenge.
• The myophosphorylase reaction provides a reliable method for demonstrating the presence of malignant hyperthermia, even post-mortem.

Implications:

• This enzyme reaction offers a powerful tool for diagnosing malignant hyperthermia, aiding in the investigation of unexplained deaths.
• It can help verify deaths occurring during or after anesthesia, or those attributed to stress ('human stress syndrome').
• The myophosphorylase reaction enhances diagnostic capabilities in cases where conventional methods are inconclusive, though it cannot predict susceptibility.