Altered Mental Status

Key considerations: Hypoglycemia, Stroke, Meningitis / Encephalitis

Cannot miss

Hypoglycemia
Stroke
Meningitis / Encephalitis
Status epilepticus (non-convulsive)
Intracranial hemorrhage
Opioid overdose
Sepsis
Wernicke encephalopathy

Likely diagnoses

Urinary tract infection (elderly)
Medication effect / polypharmacy
Alcohol intoxication
Dehydration / electrolyte imbalance
Dementia with delirium
Hepatic encephalopathy

Red flags

GCS <8 — cannot protect airway
Focal neurological deficits
Fever with AMS
Pinpoint pupils (opioid)
Seizure activity (subtle or clinical)
Rapidly deteriorating mental status
New AMS in young patient

Workup

history: Baseline mental status — get collateral from family/facility; Onset: acute vs subacute vs chronic; Recent medications changes, new prescriptions; Alcohol, drug use, access to medications; Recent illness, fever, UTI symptoms; Trauma: even minor falls in elderly; Living situation: CO exposure, heat exposure; exam: GCS scoring; Pupils: miosis (opioids, pontine stroke), mydriasis (sympathomimetics, anticholinergics); Skin: hot/dry (anticholinergic), cool/diaphoretic (hypoglycemia), jaundice (hepatic); Nuchal rigidity (meningitis); Focal neurological deficits (stroke, mass); Asterixis (hepatic/uremic encephalopathy); Track marks, medication patches (opioid source); labs: Point-of-care glucose — FIRST; CBC, BMP (Na, Ca, glucose, BUN/Cr); Urinalysis (UTI in elderly); TSH; Ammonia (hepatic encephalopathy); Drug levels: APAP, salicylate, alcohol, lithium, digoxin; Urine drug screen; Blood cultures if febrile; ABG/VBG; Coagulation studies if anticoagulated; imaging: CT head non-contrast: hemorrhage, mass, hydrocephalus, stroke; CXR: pneumonia as cause of sepsis/delirium; CT abdomen if abdominal source suspected; bedside: Point-of-care glucose — always first; 12-lead ECG: arrhythmia, drug toxicity (wide QRS from TCA); Cardiac monitor: continuous; Point-of-care ultrasound: bladder scan (urinary retention)

Management

immediate: ABC assessment — protect airway if GCS ≤8; Point-of-care glucose — give D50 if hypoglycemic; Naloxone 0.4–2mg IV/IN if opioid overdose suspected; Thiamine 100mg IV before glucose in suspected alcoholics/malnourished (prevent Wernicke); general: Systematic approach: use mnemonics AEIOU-TIPS; A: Alcohol/Acidosis, E: Electrolytes/Encephalopathy/Endocrine, I: Infection, O: Overdose/O2, U: Uremia; T: Trauma/Temperature, I: Insulin (hypo/hyperglycemia), P: Psychiatric/Porphyria, S: Stroke/Seizure/Shock; Avoid sedating medications if possible — worsens assessment; specific: diagnosis: Hypoglycemia; steps: D50 1 amp (25g) IV push; Recheck glucose in 15 minutes; Identify cause: insulin, oral hypoglycemics, alcohol, sepsis; Observe for recurrence — sulfonylurea overdose requires prolonged observation; diagnosis: Opioid Overdose; steps: Naloxone 0.4mg IV, repeat q2-3 min up to 10mg; Intranasal naloxone 4mg if no IV access; Titrate to respiratory drive, not full consciousness; Observe 4-6 hours (longer for long-acting opioids or extended-release); diagnosis: Hepatic Encephalopathy; steps: Lactulose 30mL PO/NG q1h until bowel movement, then TID; Rifaximin 550mg BID; Identify precipitant: GI bleed, infection, constipation, dietary indiscretion; Check ammonia but treat clinically; diagnosis: Wernicke Encephalopathy; steps: Thiamine 500mg IV TID x3 days (high dose for Wernicke); Classic triad: encephalopathy + ataxia + ophthalmoplegia (all 3 present in only 16%); Give thiamine BEFORE glucose — glucose metabolism depletes thiamine

Disposition

admit: Unable to identify and correct cause in ED; Persistent altered mental status; Structural brain lesion; Sepsis or severe infection; Drug overdose requiring observation or antidote infusion; discharge: AMS resolved with clear reversible cause treated; Return to baseline mental status confirmed by collateral; Reliable caregiver and follow-up; consults: Neurology: stroke, seizure, encephalitis; Toxicology: complex overdose; Psychiatry: psychiatric cause after medical clearance

Clinical pearls

Always check glucose first in AMS — it is the fastest reversible cause
Thiamine BEFORE glucose in alcoholics — giving glucose without thiamine can precipitate Wernicke encephalopathy
UTI causing AMS in elderly: very common but also overdiagnosed — ensure no other cause before attributing AMS to bacteriuria
Non-convulsive status epilepticus: consider in any patient with unexplained AMS — may need EEG to diagnose
AEIOU-TIPS mnemonic ensures you do not miss common causes of AMS

Source and review

AAN Delirium Guidelines 2014, Tintinalli Emergency Medicine 9th Edition. Last reviewed: 2024-11-01