Coma DDx


A useful way of approaching the unconscious patient is to use these three categories:

  • Coma with focal or lateralizing signs
  • Coma without focal or lateralizing signs but with meningism
  • Coma without either focal or lateralizing signs or meningism


Coma with focal or lateralizing signs

  • Cerebrovascular events (ischemic or hemorrhagic)
  • Trauma
  • Space-occupying lesions (infective or non-infective, e.g. tumours)

Coma without focal or lateralizing signs but with meningism

  • Meningoencephalitis
  • Subarachnoid haemorrhage

Coma without either focal or lateralizing signs or meningism (TOMES P)

  • Toxins/drugs
    • Numerous causes including sedatives, narcotics, alcohol, psychotropics, carbon monoxide
  • Organ failure
    • Uremic encephalopathy, hepatic encephalopathy
  • Metabolic
    • hypoxia, hypercapnoea, hyponatraemia, hyperglycaemia, hypoglycaemia, hypothermia, hyperthermia, hypoosmolality, hyperosmolarity, nutritional disorders (e.g. thiamine deficiency)
  • Endocrine
    • Adrenal insufficiency, hypopituitarism, hypothyroidism
  • Seizures (including non-convulsive epilepsy, postictal states and eclampsia)
  • Pseudocoma



  • Acidosis/ Alcohol
  • Epilepsy
  • Infection
  • Overdose
  • Uremia
  • Trauma to head
  • Insulin: too little or or too much
  • Pyschogenic
  • Stroke


  • Units of insulin
  • Narcotics
  • Convulsions
  • Oxygen
  • Non-organic
  • Stroke
  • Cocktail
  • ICP
  • Organism
  • Urea
  • Shock


  • CO2 and CO excess
  • Overdose: TCAs, Benzos, EtOH, insulin, paracetamol, etc.
  • Metabolic: BSL, Na+, K+, Mg2+, urea, ammonia, etc.
  • Apoplexy: stroke, SAH, extradural, subdural, Ca, meningitis, encephalitis, cerebral abscess, etc.

“WHIPx2” (life-threatening causes of altered mental state)

  • Withdrawal syndromes 
  • Wernickes
  • Hypertensive encephalopathy
  • Hypoglycaemia (and other metabolic causes)
  • Infections (e.g. CNS infections, septic encephalopathy)
  • Intracranial lesions (i.e. SOLs)
  • Poisons
  • Porphyria (!)

CCC Neurocritical Care Series

Critical Care


Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a 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 three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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