Dermatomyositis, suxamethonium action and atypical plasmacholinesterase.

A 19-year-old girl suffering from active dermatomyositis was given suxamethonium 60 mg during anaesthesia for termination of pregnancy. A prolonged suxamethonium action occurred which was explained by the finding of homozygous atypical plasmacholinesterase in her blood. Although no fasciculations were seen immediately after injection of the drug, a period of fasciculations progressing from the extremities to the head and trunk occurred during recovery of muscle tone. No hyperpyrexia or elevation of serum creatine phosphokinase occurred. This was ascribed to the steroid therapy she received. Plasma from four other patients suffering from dermatomyositis was also investigated and one young woman, also pregnant, was found to be heterozygous for the atypical enzyme.