Approach to Altered Mental Status
A board-focused framework for altered mental status: stabilize ABCs, check a fingerstick glucose, and give universal reversibles while working the AEIOU-TIPS differential — then anchor on the classic next-best-step vignettes (hepatic encephalopathy, Wernicke, opioid toxicity, and delirium management).
AMS is a presentation, not a diagnosis
Altered mental status (AMS) is a spectrum — from delirium (acute confusion) to stupor and coma — that signals an underlying organic derangement until proven otherwise. On the boards, the winning sequence never changes: stabilize ABCs, reflexively check a fingerstick glucose, and give universal reversibles while a broad differential is worked in parallel.
Delirium is the most testable form: an acute, fluctuating disturbance of attention and cognition that is a medical emergency — never dismissed as "sundowning" or baseline dementia without a workup.
Three questions organize every vignette:
- How depressed is consciousness? → GCS / AVPU
- Is there a focal deficit or meningismus? → drives CT / LP
- What single reversible cause fits the clues? → glucose, opioids, thiamine, sodium, ammonia
- ABCs first, then an immediate fingerstick glucose — the fastest reversible cause.
- Coma cocktail for undifferentiated AMS: Thiamine, Dextrose (D50 only if hypoglycemic), Naloxone (if opioid suspected), +/- O2.
- Give thiamine before/with glucose in alcoholics or malnourished patients — a glucose load alone can precipitate Wernicke encephalopathy.
- Naloxone treats respiratory depression (RR <12); miosis (pinpoint pupils) supports opioid toxicity but is not itself the reason to give it.
- Sodium is reversible, but correct hyponatremia slowly — raising Na >8 mEq/L/24h risks osmotic demyelination (central pontine myelinolysis).
- Vitals drive the DDx: fever → infection/meningitis; hypertension + bradycardia + irregular breathing (Cushing triad) → raised ICP; hyperthermia + rigidity → NMS/serotonin syndrome; both hypo- and hyperthermia cause AMS.
- Inattention is the clinical hallmark of delirium (can't recite the months backward / poor digit span).
- Common precipitants in a hospitalized elder: infection (UTI, pneumonia), deliriogenic drugs (anticholinergics, benzodiazepines, opioids), and metabolic upset.
AEIOU-TIPS — the differential for AMS/coma:
- A — Alcohol, Acidosis
- E — Electrolytes, Endocrine, Encephalopathy (hepatic/uremic)
- I — Insulin (hypo-/hyperglycemia)
- O — Oxygen (hypoxia/hypercapnia), Opiates
- U — Uremia
- T — Trauma, Temperature (hypo-/hyperthermia)
- I — Infection (sepsis, meningitis, encephalitis)
- P — Poisoning, Psychiatric
- S — Stroke, Seizure (postictal), SAH, Shock
"DON'T" — reflex empiric therapies in undifferentiated coma: Dextrose, Oxygen, Naloxone, Thiamine (give thiamine first in the malnourished, before dextrose).
Delirium vs. dementia
| Feature | Delirium | Dementia |
|---|---|---|
| Onset | Acute (hours–days) | Insidious (months–years) |
| Course | Fluctuating, worse at night | Slowly progressive, stable day-to-day |
| Attention | Impaired (hallmark) | Preserved until late |
| Consciousness | Clouded / altered | Normal until late |
| Hallucinations | Common (visual) | Uncommon early |
| Reversibility | Usually reversible | Usually irreversible |
| Approach | Find + treat underlying cause | Rule out reversible mimics |
Vignette: A 58-year-old man with cirrhosis is brought in confused and lethargic. Exam shows scleral icterus, ascites, and a flapping tremor when the wrists are extended. He has been constipated for several days.
Buzzword: asterixis + cirrhosis. Diagnosis: Hepatic encephalopathy, likely precipitated by constipation (other triggers: GI bleed, infection/SBP, hypokalemia/alkalosis, dehydration, sedatives, TIPS). Next best step: Identify and treat the precipitant and start lactulose, titrated to 2–3 soft stools/day; add rifaximin for recurrent/refractory disease.
Board traps:
- Ammonia supports the diagnosis but you do not treat to a number or trend it.
- Do not restrict dietary protein.
- Always hunt for a trigger — paracentesis to exclude SBP, and look for a GI bleed.
Vignette: A disheveled man with heavy alcohol use is found confused. Exam: ophthalmoplegia (lateral gaze palsy / nystagmus), a wide-based ataxic gait, and global confusion. An intern hangs D5W and he worsens.
Buzzword triad: confusion + ophthalmoplegia + ataxia = Wernicke encephalopathy (thiamine/B1 deficiency). Next best step: IV thiamine — given before or with any glucose, because a carbohydrate load in a thiamine-deficient patient can precipitate or worsen Wernicke.
Key points:
- The full triad appears in only a minority (~10–30%) — treat empirically when any single feature occurs in an at-risk patient; don't wait for all three.
- It is a clinical diagnosis — treat empirically, don't wait for a level.
- Untreated it progresses to Korsakoff syndrome: irreversible anterograde amnesia + confabulation.
- MRI (not required to treat) may show mammillary body, medial thalamic, or periaqueductal changes.
- First-tier labs: fingerstick glucose, CBC, BMP (Na, Ca, BUN/Cr, glucose), LFTs + ammonia, TSH, ABG, UA, tox screen, blood cultures if febrile.
- Non-contrast head CT when there is head trauma, a focal neurologic deficit, anticoagulation, papilledema, or no metabolic cause identified.
- Lumbar puncture for suspected meningitis/encephalitis (fever + AMS ± headache/neck stiffness). Do CT first only if focal deficit, papilledema, or immunocompromise — but do not delay empiric antibiotics ± acyclovir.
- EEG when the exam is "off" with no cause — think nonconvulsive status epilepticus (persistent AMS after a seizure, or unexplained coma).
- Avoid empiric flumazenil — it can precipitate seizures in chronic benzodiazepine users.
Nonpharmacologic measures are first-line:
- Treat the underlying cause — this is the actual therapy.
- Reorient frequently; restore the sleep–wake cycle; provide glasses/hearing aids; mobilize early; remove tethers (Foley, lines, restraints) — restraints worsen agitation and delirium.
- Ensure hydration/nutrition, treat pain, and stop deliriogenic drugs (anticholinergics, benzodiazepines, opioids, sedative-hypnotics).
Pharmacologic — only for severe agitation endangering the patient or staff:
- Low-dose antipsychotic (e.g., haloperidol or an atypical), shortest duration; check the QTc.
- Avoid antipsychotics in Parkinson disease / Lewy body dementia (severe neuroleptic sensitivity) — use low-dose quetiapine if one is unavoidable.
- Avoid benzodiazepines — they worsen delirium — except when the cause is alcohol or benzodiazepine withdrawal (or seizures), where benzos are first-line.
- Prevention bundles (sleep, mobility, orientation, hydration) beat treatment and lower incidence.
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