pralidoxime and Miosis

Amitraz is used as an ectoparasiticide for dogs and cattle. Human poisoning due to amitraz may be misdiagnosed as organophosphate/carbamate (OPC) toxicity, since amitraz poisoning shares several clinical features (miosis, bradycardia and hypotension) encountered with OPC poisoning. A 19-year-old man with an alleged history of suicidal ingestion of a pesticide presented with drowsiness and was found to have constricted pupils, hypotension and bradycardia. He was diagnosed as a case of OPC poisoning and was treated with atropine and pralidoxime prior to presentation to our centre. Absence of a hypersecretory state, and the presence of hyperglycaemia and hypothermia along with a normal serum cholinesterase level suggested an alternate possibility. Retrieval of the poison container confirmed the diagnosis of amitraz poisoning. The patient made a rapid recovery with supportive management. Clinician awareness is key to successful management of this poisoning, which carries a good prognosis.

Topics: Atropine; Bradycardia; Cholinesterase Reactivators; Diagnosis, Differential; Diagnostic Errors; Follow-Up Studies; Humans; Hyperglycemia; Hypotension; Male; Miosis; Organophosphate Poisoning; Parasympatholytics; Pralidoxime Compounds; Suicide, Attempted; Toluidines; Treatment Outcome; Young Adult

We report a 60-yr-old woman with schizophrenia, who manifested a neuroleptic malignant (NM)-like syndrome after acute organophosphate poisoning (OPP). She attempted suicide by ingesting 40% emulsions of DMTP (S-2,3-dihydro-5-methoxy-2-oxo-1,3,4-thiadizol-3-yl-methyl O,O-dimethyl phosphorodithioate) 100 ml. On admission, she was unconscious and demonstrated convulsions, depressed respiratory movements, miosis and profuse salivation. Plasma cholinesterase concentration (842 IU.L-1) was very low and OPP was diagnosed. She was treated with gastric lavage, atropine and pralidoxime (PAM). By the seventh day after admission, symptoms of OPP disappeared and serum ChE had recovered to a sub-normal level. On the 13th day, she demonstrated coma, high fever (41.0 degrees C) and lead-pipe rigidity. Serum CPK was increased (1631 IU.L-1). Dantrolene sodium iv was administered for three days. Body temperature began to decrease in 24 hr, and her consciousness, muscle rigidity and other neurological symptoms returned to normal by the 16th day after admission. She was discharged from the hospital without sequelae 55 days after admission. We conclude that OPP can predispose to an NM-like syndrome and that dantrolene may be effective in the management.

Topics: Atropine; Cholinesterase Reactivators; Cholinesterases; Dantrolene; Female; Humans; Middle Aged; Miosis; Muscarinic Antagonists; Muscle Relaxants, Central; Neuroleptic Malignant Syndrome; Organophosphate Poisoning; Organothiophosphorus Compounds; Poisoning; Pralidoxime Compounds; Respiration; Salivation; Schizophrenia; Seizures; Suicide, Attempted; Therapeutic Irrigation