PROLONGED PARALYSIS DUE TO NONDEPOLARIZING NEUROMUSCULAR BLOCKING-AGENTS AND CORTICOSTEROIDS

The long-term use of nondepolarizing neuromuscular blocking agents (ND -NMBA) has recently been implicated as a cause of prolonged muscle wea kness, although the site of the lesion and the predisposing factors ha ve been unclear. We report 3 patients (age 37-52 years) with acute res piratory insufficiency who developed prolonged weakness following the discontinuation of ND-NMBAs. Two patients also received intravenous co rticosteroids. Renal function was normal but hepatic function was impa ired in all patients, and all had acidosis. Electrophysiologic studies revealed low amplitude compound motor action potentials, normal senso ry studies, and fibrillations. Repetitive stimulation at 2 Hz showed a decremental response in 2 patients. The serum vecuronium level measur ed in 1 patient 14 days after the drug had been discontinued was 172 n g/mL. A muscle biopsy in this patient showed loss of thick, myosin fil aments. The weakness in these patients is due to pathology at both the neuromuscular junction (most likely due to ND-NMBA) and muscle (most likely due to corticosteroids). Hepatic dysfunction and acidosis are c ontributing risk factors. (C) 1994 John Wiley & Sons, Inc.