A 58-year-old patient presents with miosis, abdominal cramping, salivation, bradycardia, and muscle weakness. The most likely diagnosis is which condition?

A 58-year-old patient presents with miosis, abdominal cramping, salivation, bradycardia, and muscle weakness. The most likely diagnosis is which condition?

• A. Central anticholinergic syndrome
• B. Malignant neuroleptic syndrome
• C. Anticholinesterase poisoning
• D. Digitalis overdose

Answer: (C)

This scenario illustrates cholinergic excess from anticholinesterase inhibition. When acetylcholinesterase is blocked, acetylcholine accumulates at both muscarinic and nicotinic receptors. The muscarinic effects produce secretions and smooth-muscle activity—salivation and abdominal cramping, plus miosis and bradycardia. The accompanying muscle weakness reflects nicotinic receptor stimulation at the neuromuscular junction. Together, these signs form the classic cholinergic (anticholinesterase) poisoning picture. Other conditions don’t fit as well because they produce different symptom patterns. Central anticholinergic syndrome tends to cause pupil dilation, dry mucous membranes, tachycardia, and mental status changes rather than excessive secretions and miosis. Malignant neuroleptic syndrome presents with hyperthermia, severe rigidity, and autonomic instability, not a cholinergic excess. Digitalis overdose causes GI symptoms and various arrhythmias, often with visual disturbances, but not the marked muscarinic secretions and miosis seen here. If this were an exam scenario, recognizing the cholinergic syndrome would also cue you to treatments like atropine to block muscarinic effects and pralidoxime if organophosphate poisoning is suspected.

This scenario illustrates cholinergic excess from anticholinesterase inhibition. When acetylcholinesterase is blocked, acetylcholine accumulates at both muscarinic and nicotinic receptors. The muscarinic effects produce secretions and smooth-muscle activity—salivation and abdominal cramping, plus miosis and bradycardia. The accompanying muscle weakness reflects nicotinic receptor stimulation at the neuromuscular junction. Together, these signs form the classic cholinergic (anticholinesterase) poisoning picture.

Other conditions don’t fit as well because they produce different symptom patterns. Central anticholinergic syndrome tends to cause pupil dilation, dry mucous membranes, tachycardia, and mental status changes rather than excessive secretions and miosis. Malignant neuroleptic syndrome presents with hyperthermia, severe rigidity, and autonomic instability, not a cholinergic excess. Digitalis overdose causes GI symptoms and various arrhythmias, often with visual disturbances, but not the marked muscarinic secretions and miosis seen here.

If this were an exam scenario, recognizing the cholinergic syndrome would also cue you to treatments like atropine to block muscarinic effects and pralidoxime if organophosphate poisoning is suspected.