American Board of Psychiatry and Neurology (ABPN) Practice Exam

In organophosphate poisoning, specific symptoms arise due to the inhibition of acetylcholinesterase, leading to an accumulation of acetylcholine at synapses. Common symptoms associated with this exposure include increased secretions and increased parasympathetic activity. Lacrimation, salivation, and diarrhea all fall under the category of cholinergic effects characterized by excessive secretion. Lacrimation refers to increased tear production, salivation involves excessive drooling, and diarrhea results from enhanced gastrointestinal motility and secretion. These symptoms are indicative of overstimulation of the cholinergic system. Mydriasis, which is the dilation of the pupils, is not a symptom typically associated with organophosphate exposure. In fact, organophosphates typically induce miosis (constriction of the pupils) rather than mydriasis because they enhance cholinergic activity, which tightens the iris sphincter muscle, leading to pupil constriction. Therefore, the absence of mydriasis as a symptom distinguishes it from the other listed symptoms associated with organophosphate toxicity.