A series of recent reports have identified cases of a quadriplegic myo
pathy characterized by myofiber necrosis and loss of myosin filaments
associated with the use of nondepolarizing muscle blocking agents and
glucocorticoids. We report electrophysiological findings in 7 intensiv
e care unit patients who developed evidence of an acute myopathy in as
sociation with the use of nondepolarizing muscle blocking agents Sever
al important features were identified: (i) a neuromuscular transmissio
n deficit was observed in 3 patients up to 7 days following withdrawal
of vecuronium; (ii) motor M potentials were of low amplitude, there w
as mild abnormal spontaneous activity on needle electromyography, and
sensory conduction was relatively preserved; (iii) not ail patients re
ceived glucocorticoids or were asthmatic; (iv) 2 patients given vecuro
nium had Very high creatine kinase levels and developed acute renal fa
ilure associated with myoglobinuria; and (v) rises in motor M potentia
ls accompanied clinical recovery. This complication of intensive care
may be severe, but is reversible and possibly avoidable. Our findings
implicate nondepolarizing muscle blocking agents in the development of
the myopathy. Electrophysiological studies provide important prognost
ic guidance. (C) 1994 John Wiley and Sons, Inc.