Pathological myophosphorylase reaction in malignant hyperthermia

In malignant hyperthermia, myophosphorylase reaction shows characteristic changes that take place within minutes: (1) a generally strongly weakened reaction; (2) numerous negatively reacting fibres; (3) frequently, fibre sections that show spotty and/or striatal weak or negative reactions and fibre sections with strong striatal reactions with relatively narrow sarcomere spacings (a "sign of hypercontraction"). Obviously, the morphological findings that show characteristic "striated fibres" are typical of the malignant hyperthermia syndrome! It is important to note that the muscular fibres showing such changes are, as a rule, inconspicuous when using other stains and reactions. These pathological myophosphorylase reactions were observed in five deceased patients (one independently of anaesthesia after an extended walk) and in 19 pigs (18 times after halothane testing and once in an experimental animal with clinical evidence of the presence of malignant hyperthermia). These reactions were not noted in pigs with negative halothane reactivity or prior to halothane testing. They were also not seen in a large number of very different healthy and diseased control and reference cases from our biopsy and autopsy material. Myophosphorylase reaction enables convincing demonstration of malignant hyperthermia, past or present. Hence, it is possible to elucidate puzzling deaths or verify apparently clear death occurring during or subsequent to anaesthesia or simply following stress ("human stress syndrome"). Many of these deaths doubtlessly escape the attention of clinicians using the usual morphological examination methods. However, the reaction cannot be used to identify potential victims.