Prolonged muscle rigidity following administration of succinylcholine

Succinylcholine should be avoided in any patient with known myotonia because of the possibility of an abnormal rigid response. In addition, the possibility of undiagnosed myotonia should be considered in any myopathic patient. While not all myotonic responses are associated with malignant hyperthermia, the anesthetic should be discontinued immediately and the patient should be closely observed for elevation of temperature.