ACUTE MYOPATHY ASSOCIATED WITH LARGE PARENTERAL DOSE OF CORTICOSTEROID IN MYASTHENIA-GRAVIS

A 13 year old Greek girl with myasthenia gravis developed widespread m uscle paralysis and atrophy after large parenteral doses of corticoste roids (5.48 g methylprednisolone). An electromyogram showed myopathy, creatine kinase concentration below normal, and a muscle biopsy showed severe myopathy with selective loss of the thick filaments (myosin). Previous reports of myopathy associated with large steroid doses have mostly been in patients who were also receiving non-depolarising neuro muscular blocking drugs. This patient is unique in that severe myopath y was associated with neuromuscular blockade caused by antibodies to a cetylcholine receptors. The findings in this case suggest that high do ses of parenteral corticosteroids in patients with myasthenia gravis m ay be dangerous and that blocking the neuromuscular junction with drug s or antibodies predisposes skeletal muscles to the injurious effects of corticosteroids.