09 February 2016

A better way to think about Altered Mental Status

I recently had occasion to prepare a talk on the various causes of Altered Mental Status. As it happens, EM:RAP had a nice Continuous Core Content segment recently on the same topic. (Don't listen to EM:RAP? You should. Want to try it for free? Rob Orman of ERCast has an offer for a three month free trial. Use the code ERTHANKS.)* They used a practical case-based format to structure the approach, which I like, but also fell back on the old mnemonic of AEIOU TIPS. God I hate that mnemonic. It's so haphazard and utterly disorganized: just like the typical approach to AMS.

A — Alcohol/Acidosis (not the same thing or in any way logically connected) 
E — Endocrine/Epilepsy/Electrolytes/Encephalopathy (E is a common letter?) 
I — Infection or maybe Ingestion who the hell knows nobody agrees
O — Opiates, Overdose (sorta the same thing but ehhh) 
U — Uremia (not likely but something's gotta start with U) 
T — Trauma (garbage pail) 
I — Insulin (huh?) 
P — Poisoning/Psychosis 
S — Stroke/Seizure/syncope (wait syncope doesn't, and wasn't epilepsy already covered?) 

This is just terrible. Too many things thrown into too few headers with absolutely no logical connection between any of them and criminally incomplete to boot. Bad for learners, and pretty useless for recall too. My approach was to ask myself, well, AMS basically means the brain's not working right, right? Let's group the causes of AMS by the mechanism by which they make the brain not work right. So that's what I did. It is offered here for your perusal and amusement and maybe even use.

Things your brain needs to live and function

  • ↓ Oxygen/Glucose (fix these immediately)

Things that squish the brain

  • Blood where it should not be: Subdural, Epidural, Intracerebral, Subarachnoid
  • Blood that has clotted where it should not: Dural Sinus Thrombosis
  • Masses and tumors
  • Obstructive Hydrocephalus
  • Edema: Traumatic, posthypoxic, hypertensive, vasogenic, PRES

Bad things living in the brain

  • Meningitis
  • Encephalitis: viral, inflammatory, autoimmune
  • Abscesses
  • Syphilis/Amebas/Cysts

Primary brain not workings

  • Acute Ischemic Stroke
  • Concussion/Diffuse Axonal Injury
  • Seizure, Status epilepticus (may not be convulsive), post-ictal state
  • Migraine
  • Degenerative conditions: MS, Parkinson’s, TBI, Dementias sundry
    • BONUS POINTS for this plus another cause

Delirium and Encephalopathies and Various Failures of Homeostasis

  • Sepsis and other shock states (hypoperfusion)
  • Systemic infection without sepsis
  • Fever, Hyperthermia and Hypothermia
  • Dehydration, ↑Na, ↑Glucose (HONK and/or DKA)
  • ↑/↓ Ca, ↓Na, ↑/↓K
  • ↑/↓ Thyroid, Adrenal Crisis

Bad Things in the Blood

  • EtOH (rare)
  • Endogenous bad things
    • ↑CO2, Uremia, Ammonia
  • Medicines that can mess you up when used as intended
    • Opiates, benzodiazepines, imidazopyridines (ambien et al)
  • Medicines that will mess you up when you get too much of them
    • Lithium, Tricyclics, Anticonvulsants, Antihistamines, Salicylates
  • Things that you are not allowed to have in your blood because it is a crime
    • Meth, cocaine, heroin, MaryJane, GHB, ketamine, spice, bath salts, etc etc.
  • Things that you are not supposed to have in your blood because they are poison
    • Carbon monoxide, cyanide, pesticides, other alcohols, hydrocarbons and solvents, etc etc
  • Unique weird reactions to things:
    • Alcohol Withdrawal, Neuroleptic Malignant Syndrome, Serotonin Syndrome, Agitated Delirium, Wernicke's

Maybe You’re Just Crazy?

  • Conversion Disorder
  • Psychosis/Mania
  • Malingering
  • These are last on the list for a reason
This is by no means an exhaustive list (I get exhausted just thinking about all the bad things in the blood) but rather a mode of thinking about the potential causes for a patient with AMS. Also, the astute reader will note that it is neither sorted by frequency nor by approach to workup (though that would be fun to categorize. "Things you will see on CT"; "Things you will diagnose when the hospitalist forces you to do an LP"; "Things that will require a Neuro consult" etc.) Enjoy, and remember, no matter what, always check the fecking glucose.

*I'm not getting paid by EM:RAP. But I will probably make Rob buy the first round the next time we are both at the same conference.


  1. I like it, but man, it always seems to be multifactorial. Of course, since I'm a medicine hospitalist, if it's a single factor, it usually gets triaged to a specialty team before they get out of the ED.

    Dementia + a UTI + AKI on CKD w/uremia + Delirium


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