LETTER
Prolonged Weakness and Vecuronium
Michio Hirano;
Eric C. Raps; and
Jay Cowen
1 April 1993 | Volume 118 Issue 7 | Pages 569-571
TO THE EDITOR:
A growing body of literature describes prolonged weakness after concomitant administration of corticosteroids and nondepolarizing neuromuscular blocking drugs [1-4]. Most of these patients suffer from a severe myopathy. In our review [3], we found 33 patients with moderate to severe weakness, noted 4 days to 2 weeks after initiation of high-dose corticosteroids. Approximately 90% (30 of 33) of the patients were given nondepolarizing neuromuscular blocking agents (pancuronium or vecuronium). The serum creatine kinase level was often but not always elevated (10 of 16 patients). On nerve conduction studies and electromyography, 6 of 19 patients showed evidence of neuropathy, but 9 were consistent with a myopathy. Muscle biopsies showed a myopathy in 14 of 17 patients (82%). Several reports have consistently shown a severe atrophy of muscle fibers with myofibril disorganization and selective loss of myosin [3].
A second group of patients appear to have prolonged paralysis caused by extended action of the neuromuscular blocking agents at the neuromuscular junction [4, 5] in the setting of renal or hepatic failure. These patients seem to have slow elimination of the drugs and of the active 3-desacetylvecuronium metabolite.
Kupfer and colleagues [1] failed to describe in detail steroid use in their patients. The electrophysiologic data do not convincingly support a neurogenic disorder. The sensory nerve action potential amplitudes were reported as normal in nine of ten patients; thus, the likelihood of a sensory-motor neuropathy is remote. The low motor compound action potential amplitudes may reflect either a motor neuropathy or a severe myopathy. The descriptions of motor unit potentials and their recruitment patterns were not detailed. Furthermore, Kupfer and coworkers [1] did not do muscle or nerve biopsies to confirm the causes of the patients' weakness. Patients 3 and 10 appear to have had prolonged weakness caused by delayed elimination of the neuromuscular blocking agent. We think that myopathy, not neuropathy, caused the prolonged weakness in the other five patients.
1. Kupfer Y, Namba T, Kaldawi I, Tessler S. Prolonged weakness after long-term infusion of vecuronium bromide. Ann Intern Med. 1992; 117:484-6.
2. MacFarlane I, Rosenthal F. Severe myopathy after status asthmaticus. Lancet. 1977; 2:615.
3. Hirano M, Ott BR, Raps EC, Minetti C, Lennihan L, Libbey NP, et al. Acute quadriplegic myopathy: a complication of treatment with steroids, nondepolarizing blocking agents, or both. Neurology. 1992; 42:2032-7.
4. Coursin DB. Neuromuscular blockade: should patients be relaxed in the ICU? Chest. 1992; 102:988-9.
5. Segredo V, Caldwell JE, Matthay MA, Sharma ML, Gruenke LD, Miller RD. Persistent paralysis in critically ill patients after long-term administration of vecuronium. N Engl J Med. 1992; 327:524-8.
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