Intermediate Myasthenia Syndrome Following Organophosphate Intoxication

ABSTRACT

BACKGROUND: Intermediate myasthenia syndrome(IMS) is thought to have clinical importance because it may cause sudden respiratory failure during the recovery phase of a cholinergic crisis of organophosphate poisoning. We designed this study to identify the prevalence, the inducing agent, clinical predictor, and the proposed treatment of IMS. METHODS: Patients who had admitted with the diagnosis of acute organophosphate poisoning from 1992 to 1998 at two teaching hospitals were enrolled in this study. We selected the cases of IMS based on a review of medical records using modified He's criteria. RESULTS: Twelve(12) out of 110 patients with acute organophosphate poisoning were diagnosed for a prevalence at 10.9%. The drug inducing IMS were identified as dichlorvos, fenthion, EPN, methidathion, and phosphamidon. The occurrence of IMS was not related to either the initial treatment with atropine and pralidoxime, or the level of serum cholinesterase. Complications were pneumonia, sepsis, pancreatitis, and pseudomembranous colitis, etc. Eleven(11) patients were discharged without sequelae, and one patient was discharged as a hopeless care. CONCLUSION: This study suggests that IMS is not rare, so close observation is required to detect IMS in organophosphate-poisoning patients. Also, more studies are required to find predictors and treatments.