39 year-old obese man; suffered fatal malignant hyperthermia after undergoing general anesthesia for gall bladder surgery.

H&E Many internal nuclei and atrophic fibers
ATPase pH 4.3
(H&E) scattered fiber necrosis with acute macrophage infiltrates
NADH reductase histochemistry

Diagnosis: Nonspecific myopathic changes The significance of the findings is that there are specific myopathies associated with susceptibility to malignant hyperthermia following general anaesthesia. The most distinctive such myopathy is central core myopthy, which are easily recognizable by the central cores (on cross-section) on either ATPase or NADH reactions. Central core myopathy is associated with a defect in the calcium release channel of the sarcoplasmic reticulum (ryanodine receptor). The present case showed no central cores. Reviews: Wappler F Eur J Anaesthesiol 2001 Oct;18(10):632-52 Hogan K. The anesthetic myopathies and malignant hyperthermias. Curr Opin Neurol. 1998 Oct;11(5):469-76. This page created on a Macintosh using PhotoPage by John A. Vink.