Intermediate Syndrome Following Acute Organophosphate Poisoning: Correlation with Initial Serum Levels of Muscle Enzymes*

Abstract: Following acute organophosphate poisoning, intermediate syndrome essentially relates to the impairment of neuromuscular transmission due to prolonged inhibition of acetylcholinesterase activity at the muscle end-plate. However, the role of muscle injury in the development of intermedicate syndrome is not clear. The aim of this study was to determine whether the initial serum levels of the muscle enzymes can predict the subsequent development of intermediate syndrome. We reviewed the files of 47 adult patients with organophosphate poisoning between April 2003 and February 2006. The muscle enzymes were obtained within first 24 hr from each patient. Among the patients, 17% (n = 8) had severe poisoning and 83% (n = 39) mild poisoning. In 10 patients (21%), intermediate syndrome was observed. Of the patients with severe poisoning, 63% (n = 5) developed subsequent intermediate syndrome; among those with mild poisoning, 13% (n = 5) developed intermediate syndrome. There was no significant difference in initial serum levels of creatine kinase and aspartate aminotransferase between the patients with severe poisoning and mild poisoning, and there was no difference in initial serum levels of creatine kinase and aspartate aminotransferase between the patients with and without intermediate syndrome. The serum levels of the muscle enzymes measured within the first 24 hr may not predict the subsequent development of intermediate syndrome.