Differentials
Carbamate poisoning
SIGNS / SYMPTOMS
Essentially clinically indistinguishable from organophosphate poisoning, as some carbamate pesticides are anticholinesterases.
A more rapid onset and resolution suggest this diagnosis.
INVESTIGATIONS
There are no clinical differentiating tests.
Chlorophenoxy herbicide poisoning
SIGNS / SYMPTOMS
Chest signs, pinpoint pupils, and increased secretions are not expected.
INVESTIGATIONS
Cholinesterase activity is expected to be normal.
Rhabdomyolysis is common in severe poisoning.
Opioid overdose
SIGNS / SYMPTOMS
Pinpoint pupils and decreased consciousness, but excessive secretions are minimal and fasciculations will not generally be seen.
INVESTIGATIONS
A response to naloxone is diagnostic. There may also be a positive urine drug screen. Cholinesterase activity is expected to be normal.
Brainstem stroke
SIGNS / SYMPTOMS
Grossly excessive secretions are not seen.
INVESTIGATIONS
Response to atropine and cholinesterase activity is expected to be normal.
Imaging of the head may detect stroke; however, images may appear normal early on.
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