The complication rate of edrophonium testing for suspected myasthenia gravis.

BACKGROUND: The incidence of life-threatening complications from edrophonium chloride (Tensilon) testing for suspected myasthenia gravis is thought to be extremely low. We carried out a survey to determine the rate of serious complications from such testing.

METHODS: In April 1998, 357 physicians listed in the 1998 roster of the North American Neuro-ophthalmology Society were mailed a questionnaire for anonymous completion. Questions asked included the number of years the clinician had practised neuro-ophthalmology, the estimated number of edrophonium tests performed since completion of training, the number and nature of major complications from edrophonium, and whether the clinician preferred the sleep test or ice test to edrophonium testing.

RESULTS: The response rate was 56% (199/357). Of the 199 respondents, 105 (53%) had practised neuro-ophthalmology for at least 10 years. The group estimated that they had performed at least 23,111 edrophonium tests, of which 37 (0.16%) were associated with a serious complication, mostly attributed to brady-arrythmias and syncope. Respiratory failure, seizure, severe vomiting and transient ischemic attack were also reported. Thirty-one respondents (16%) preferred the sleep test or ice test to the edrophonium test; one-third of this group reported a serious complication with edrophonium.

INTERPRETATION: The rate of significant complications of edrophonium testing is low, but the complications can be potentially life threatening. Clinicians should know the nature and incidence of these complications when obtaining informed consent for edrophonium testing.