Toxidrome Challenge

aka Toxicology Conundrum 025

Think you’re ready for the toxidrome challenge? You’re about to find out…

How this works

The toxidromes included are those most relevant to the differential diagnosis of serotonin toxicity (see Toxicology Conundrum #024). For each toxidrome see if you can describe the classic findings for each of the clinical features listed below – click on the link to show/hide the answer.


Toxidrome challenge

Q1. What history of drug exposure is present?

Serotonin toxicity
  • 5HT2A or 5HT1A serotonin receptor agonists e.g. citalopram, ecstasy, tramadol, lithium
Neuroleptic malignant syndrome
  • Dopamine antagonists e.g haloperidol, thioridazine
Anticholinergic syndrome
  • Anticholinergic agents e.g. hyoscine, scopolamine, doxylamine
Malignant hyperthermia
  • Inhalational anesthetics, suxamethonium

Q2. What is the usual cadence of the toxidrome?

Serotonin toxicity
  • <12h
Neuroleptic malignant syndrome
  • days
Anticholinergic syndrome
  • <12h
Malignant hyperthermia
  • minutes-24h

Q3. What changes in vital signs are expected?

Serotonin toxicity
  • increased T, P, R, BP
Neuroleptic malignant syndrome
  • increased T, P, R, BP
Anticholinergic syndrome
  • increased T, P, R, BP
Malignant hyperthermia
  • increased T, P, R, BP (notice the recurring theme?)

Q4. What are the classic pupil findings?

Serotonin toxicity
  • mydriasis
Neuroleptic malignant syndrome
  • mydriasis or normal
Anticholinergic syndrome
  • mydriasis
Malignant hyperthermia
  • normal

Q5. What skin findings are classically described?

Serotonin toxicity
  • sweaty
Neuroleptic malignant syndrome
  • sweaty and pallor
Anticholinergic syndrome
  • hot, red and dry
Malignant hyperthermia
  • sweaty and mottled

Q6. Are bowel sounds normal, decreased, absent or hyperactive?

Serotonin toxicity
  • hyperactive
Neuroleptic malignant syndrome
  • normal
Anticholinergic syndrome
  • decreased or absent
Malignant hyperthermia
  • decreased

Q7. What are the typical alterations in neuromuscular tone?

Serotonin toxicity
  • increased, especially lower limbs
Neuroleptic malignant syndrome
  • lead-pipe rigidity
Anticholinergic syndrome
  • normal
Malignant hyperthermia
  • generalised rigidity

Q8. What are the classic changes in deep tendon reflexes?

Serotonin toxicity
  • hyperreflexia and clonus
Neuroleptic malignant syndrome
  • bradyreflexia
Anticholinergic syndrome
  • normal
Malignant hyperthermia
  • hyporeflexia

Q9. What mental status changes are typically found?

Serotonin toxicity
  • agitation progresses to coma
Neuroleptic malignant syndrome
  • mutism, staring, bradykinesia, coma
Anticholinergic syndrome
  • agitated delirium
Malignant hyperthermia
  • agitation

LITFL Toxicology Challenges


CLINICAL CASES

Toxicology Conundrum

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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