THE MYOTONIC RESPONSE TO SUXAMETHONIUM BY

A survey of the reported responses of myotonic patients to depolarizing relaxants reveals the variable incidence and extent of induced myotonia. Generalized myotonia due to suxamethonium is described in a patient with myotonia congenita and, from subsequent investigations during a second operation, the action of the drug is clarified. Such a myotonic response is attributed to fasciculation, and a normal depolarizing block was demonstrated with continued administration of the drug. Suggestions are made for the anaesthetic management of such patients. Among the less common diseases which may lead to an altered or dangerous response to anaesthesia are three hereditary muscle disorders comprising the myotonic syndrome. Kaufman in 1960 des-cribed the anaesthetic hazards involved, and in-cluded in his account an instance of generalized myotonia due to decamethonium. Subsequently, Paterson (1962) described a case of generalized myotonia caused by suxamethonium. In each of these patients it was not possible to inflate the lungs during the myotonic spasm. It is the purpose of this paper to describe another instance of generalized myotonic spasm caused by suxamethonium, and to offer from further observations a possible explanation of the mechanisms involved