Effective doses of vecuronium in a patient with myotonic dystrophy

Of the forms of muscular dystrophy, myotonic dystrophy has the greatest systemic involvement. Although most patients with myotonic dystrophy show normal sensitivity to non-depolarising neuromuscular blocking drugs, some have been reported to show greatly increased sensitivity to these drugs, and little is known about the sensitivity of different muscles. We compared effective doses of vecuronium in a patient with myotonic dystrophy at the orbicularis oculi, adductor pollicis and flexor hallucis brevis muscles during total intravenous anaesthesia. The calculated ED50 for the orbicularis oculi (7.77 microg x kg(-1) (95% CI 3.10-16.8 microg x kg(-1))) was lower than for the adductor pollicis (25.3 microg x kg(-1) (95% CI 20.7-43.3 microg x kg(-1))) and flexor hallucis brevis muscles (29.5 microg x kg(-1) (95% CI 11.0-85.6 microg x kg(-1); p < 0.01)). The ED90 was also lower for the orbicularis oculi (35.7 microg x kg(-1) (95% CI 14.8-66.5 microg x kg(-1))) than for the other muscles (51.8 microg x kg(-1) (95% CI 29.3-145.0 microg x kg(-1)) and 50.6 microg x kg(-1) (95% CI 5.29-642.0 microg x kg(-1)), respectively) (p < 0.01)).