Last reviewed: March 2026
Contents
MDM Templates
AMS — Transient / Resolved
Patient presents after an episode of altered mental status that has since resolved. At the time of evaluation, the patient is back to baseline mental status per patient and collateral history.
Given history, exam, and workup, presentation not consistent with dangerous emergent causes of altered mentation including stroke, CNS infection, severe metabolic derangement, intracranial hemorrhage, or significant toxidrome. Cause appears to be ***.
Plan: Discharge. Patient at baseline mental status at time of disposition. Return for recurrent confusion, fever, weakness, headache, or any new symptoms.
AMS — Persistent / Undifferentiated
Patient presents with altered mental status that persists despite initial evaluation and resuscitation. Unable to obtain reliable history from patient. Collateral obtained from ***.
Broad differential for persistent AMS includes metabolic derangement, infection/sepsis, toxicologic causes, postictal state, stroke, and intracranial hemorrhage. Workup directed at identifying reversible causes.
If no clear etiology identified: Empiric treatment for the most dangerous reversible causes (glucose, thiamine, naloxone as indicated). Social work consulted to obtain collateral information and establish baseline.
Regarding LP: Patient is afebrile, without nuchal rigidity or concerning skin findings. Suspicion for CNS infection is low and LP deferred at this time.
Plan: Admit for further workup and monitoring. Patient does not have capacity for medical decision-making at this time.
Hepatic Encephalopathy
Patient with known cirrhosis presents with altered mentation. Exam notable for asterixis. No focal neurologic deficits.
Given history of cirrhosis and clinical presentation, altered mentation most consistent with hepatic encephalopathy. Not consistent with stroke (no focal deficits), CNS infection (afebrile, no meningismus), intracranial hemorrhage (no acute headache, no trauma), or postictal state (no witnessed seizure activity). Will evaluate for precipitants including infection, GI bleeding, medication changes, and dietary indiscretion.
If significantly altered or unable to protect airway: This represents severe hepatic encephalopathy. ICU admission for airway monitoring and aggressive lactulose therapy.
Plan: Lactulose initiated. Admit. Evaluate and treat underlying precipitant.
Clinical Education
Approach to Undifferentiated AMS
AMS is a symptom, not a diagnosis. The ED job is to identify and treat dangerous reversible causes, not to definitively diagnose the etiology. Start with glucose, vitals, and a focused neuro exam. Everything else follows from there.[1]
Get collateral early. The single most valuable piece of information in undifferentiated AMS is baseline mental status. A patient who “has been like this for years” per the nursing home is a completely different workup than one who was normal this morning. Call the family, call the facility, check prior charts.
The med list is the history. In elderly patients with AMS, the medication list is often more informative than anything else. New antibiotics (fluoroquinolones), benzodiazepines, anticholinergics, opioids, and polypharmacy are the most common culprits.
Rapidly Reversible Causes
Check these immediately — they’re treatable at the bedside:
| Cause | Treatment | Pearl |
| Hypoglycemia | D50 1 amp IV | Always check POC glucose first |
| Opioid toxicity | Naloxone 0.4–2 mg IV/IM/IN | Miosis + respiratory depression = give it |
| Wernicke encephalopathy | Thiamine 500 mg IV | Give before glucose in suspected alcoholism |
| Hyponatremia | 3% NS 100–150 mL bolus | If seizing or severely altered |
| Hypoxia/hypercarbia | Supplemental O2, BiPAP, intubation | Check a VBG — CO2 retainers look altered |
Delirium vs Dementia
Delirium is acute, fluctuating, and has a cause. Dementia is chronic and stable. The most common mistake is attributing delirium to known dementia. “He has Alzheimer’s” is not an explanation for why he’s suddenly more confused than his baseline. Demented patients get delirious too — and the delirium trigger is the thing that needs treatment.[2]
Hypoactive delirium is more common and more dangerous than agitated delirium. The quiet, staring patient who isn’t making trouble gets less attention but has higher mortality. Don’t confuse calm with well.
UTI as a cause of AMS is massively overdiagnosed. A positive UA in an elderly patient is nearly meaningless — asymptomatic bacteriuria is present in up to 50% of institutionalized elderly. A dirty UA does not explain AMS unless the patient is also febrile, septic, or has urinary symptoms. Look harder for the real cause.[3]
Hepatic Encephalopathy Pearls
Ammonia levels do not correlate with severity and should not guide treatment. Treat the clinical picture. A normal ammonia does not rule out hepatic encephalopathy, and a high ammonia in a cirrhotic who is at baseline is meaningless. The level is useful only to confirm the diagnosis in the first episode or when uncertain.[4]
Always look for the precipitant. Hepatic encephalopathy rarely occurs in a vacuum. The most common triggers are GI bleeding, infection (especially SBP), constipation, medication changes (new sedatives, diuretics), and dietary protein load. Finding and treating the trigger matters more than the lactulose.
Lactulose takes 24–72 hours to work. For significantly altered patients, lactulose enema (300 mL in 700 mL water, retain 30 min) works faster than oral. Rifaximin 550 mg PO BID is added for recurrent episodes — it reduces recurrence by ~50% but is expensive and usually initiated as an outpatient.
| West Haven Stage | Presentation | Disposition |
| 1 — Minimal | Mild confusion, shortened attention span | May discharge with close follow-up |
| 2 — Moderate | Disorientation, asterixis, drowsy but follows commands | Admit — may discharge if improves with lactulose |
| 3 — Severe | Marked disorientation, somnolent, unable to follow commands | Admit |
| 4 — Coma | Unresponsive | ICU |
When to LP
LP is not routine for AMS. Consider it when there is fever with AMS, immunocompromised state, meningeal signs, or when the workup is otherwise unrevealing and you need to rule out CNS infection or subarachnoid hemorrhage. The threshold should be lower in the immunocompromised, the elderly, and patients on immunosuppressive medications who may not mount a fever.[1]
CT before LP? Per Hasbun et al., LP without preceding CT is safe if the patient has no immunocompromise, no history of CNS disease, no seizure within 1 week, age <60, normal level of consciousness, and no focal neurologic deficits. If any of those are present, CT first. But don’t delay antibiotics for imaging — give empiric antibiotics before CT if meningitis is suspected.[5]
Disposition
Discharge only if back to baseline. The key question is whether the patient’s current mental status matches their pre-illness baseline — confirmed by collateral, not by the patient themselves. “The patient says they feel fine” is insufficient if you can’t verify baseline.
Admit: Persistent AMS, no identifiable reversible cause, new focal deficits, inability to verify return to baseline, or ongoing safety concerns (aspiration risk, falls, inability to self-care).
Consider nonconvulsive status epilepticus in the patient who “won’t wake up” without obvious cause. These patients need EEG monitoring, not more imaging. It’s an underdiagnosed entity that should be on the differential for any unexplained persistent AMS, particularly in patients with a seizure history.[1]
References
- Xiao HY, Wang YX, Xu TD, et al. Evaluation and treatment of altered mental status patients in the emergency department. World J Emerg Med. 2012;3(4):270-277. PubMed
- Inouye SK, Westendorp RG, Saczynski JS. Delirium in elderly people. Lancet. 2014;383(9920):911-922. PubMed
- Nicolle LE, Gupta K, Bradley SF, et al. Clinical practice guideline for the management of asymptomatic bacteriuria: 2019 update by IDSA. Clin Infect Dis. 2019;68(10):e83-e110. PubMed
- Vilstrup H, Amodio P, Bajaj J, et al. Hepatic encephalopathy in chronic liver disease: 2014 practice guideline by AASLD and EASL. Hepatology. 2014;60(2):715-735. PubMed
- Hasbun R, Abrahams J, Jekel J, Quagliarello VJ. Computed tomography of the head before lumbar puncture in adults with suspected meningitis. N Engl J Med. 2001;345(24):1727-1733. PubMed
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