Altered Mental Status and Coma

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Diagnostic approach

• ABCDE approach
• Targeted clinical evaluation
• POC glucose
• CBC
• CMP
• UA
• ABG or VBG
• Blood cultures if infection is suspected
• LP and CSF analysis if meningitis or encephalitis are suspected
• Urine tox screen
• Head imaging based on clinical suspicion
• Chest x-ray
• 12-lead ECG

Management checklist

• IV access
• Treat respiratory failure.
• Immediate hemodynamic support for shock
• Treat hypoglycemia.
• Administer antidotes (e.g., naloxone).
• IV fluids and broad-spectrum antibiotics for sepsis
• Reperfusion therapy for ischemic stroke
• Manage the underlying cause.

Red flag features

• No response to pain
• Decorticate posturing or decerebrate posturing
• Focal neurological deficits
• Absent pupil, corneal, and/or cough reflexes

Life-threatening causes

• Respiratory failure
• Hypoglycemia
• Hyperglycemic crises
• Opioid overdose
• Alcohol withdrawal
• Cyanide poisoning
• CO poisoning
• Hyperthermia
• Hypothermia
• Shock
• Sepsis
• Meningitis
• Hypertensive encephalopathy
• Imminent brain herniation

Altered mental status (AMS) is an acute change in cognitive function, psychological function, and/or level of consciousness and can manifest with confusion, behavioral changes, and changes in alertness ranging from hyperalertness to somnolence or even coma. There are many potential causes of altered mental status, including primary CNS processes, general medical conditions, substance use, and psychiatric illness. Initial management includes stabilization (e.g., definitive airway management) and screening for life-threatening acutely reversible causes (e.g., hypoglycemia, opioid overdose). Coma scores are used to assess and monitor the level of neurological dysfunction. Once stabilized, a full diagnostic evaluation should be performed based on the suspected underlying etiology; this may include basic laboratory studies, ECG, head imaging, and lumbar puncture. Treatment is focused on the management of the underlying etiology in addition to providing supportive care and preventing complications.

The following are possible causes of AMS and coma. See “Coma mimics” for differential diagnoses in which consciousness is preserved (e.g., locked-in syndrome, akinetic mutism).

Causes of altered mental status and coma: AEIOU TIPS (Alcohol, Epilepsy/Electrolytes/Endocrine, Insulin, Overdose/Oxygen, Uremia, Trauma/Temperature, Infection, Poisons/Psychiatric, Stroke/Seizures/Shock) [5]

Gradual onset of AMS or coma suggests infection, metabolic processes, or an enlarging space-occupying lesion. [2]

• Altered mental status can manifest as:
  • Hyperalertness
  • Somnolence
  • Lethargy
  • Obtundation
  • Stupor
• Coma manifests as depressed consciousness with no response to voice, pain, or other stimulation.
• Clinical features of underlying AMS etiologies may be present, e.g.:
  • CNS causes focal neurological deficits, lateralizing signs, seizures, meningismus
  • Overdose or substance use: classic toxidromes
  • Respiratory causes: tachypnea or respiratory depression
  • Hepatic causes: jaundice, prolonged bleeding, pruritus
  • Endocrine causes: clinical features of hypothyroidism, clinical features of thyrotoxicosis
  • Clinical features of TBI

General principles

• Use coma scores (e.g., GCS, AVPU scale, FOUR score) for a more objective and reproducible assessment.
• Document the score upon presentation.
• Frequently reassess to detect changes early.

AVPU scale

An abbreviated scale that helps rapidly classify and communicate a patient's level of consciousness in emergency settings. [6][7]

• A: Alert
• V: responsive to Verbal stimuli
• P: responsive to Painful stimuli
• U: Unresponsive

Glasgow coma scale (GCS) [8]

A standardized scale used to assess the level of consciousness and neurological status in multiple settings, e.g., TBI classification. GCS is less useful in intubated patients and does not provide a detailed assessment of brainstem function.

Full Outline of UnResponsiveness (FOUR) score [8]

The FOUR score is equally useful in nonintubated and intubated patients and is more discriminatory than GCS in patients with very low levels of consciousness [10][11]

Consider using the FOUR score instead of GCS to assess intubated patients, as it does not rely on verbal responses. [8]

The goal of initial management is to identify and treat rapidly reversible and/or time-sensitive critical causes of AMS prior to a full diagnostic evaluation.

Initial evaluation [2][8]

See also: “Evaluating disability in the ACBDE approach.”

• Perform an ABCDE survey.
• Identify clinical features of underlying AMS etiologies.
• Calculate coma scores (or CAM score for suspected delirium).
• Check POC glucose.
• Start continuous cardiac monitoring and pulse oximetry.
• Obtain IV access and send routine laboratory studies (see “Diagnostics for AMS”).
• Plan for early neuroimaging if CNS cause is suspected.
• Obtain collateral history from witnesses

Use coma scores to quickly assess and document neurological function at presentation and regularly reassess to detect changes.

In patients with abrupt-onset AMS or coma, consider seizure, stroke, cardiac event, overdose, or intoxication. [2]

Managing critical causes of AMS [2][8]

Perform the following concurrently with the initial evaluation, based on clinical suspicion:

• Address rapidly-reversible causes, e.g.:
  • Treat respiratory failure with oxygen therapy, bag-mask ventilation, and/or mechanical ventilation.
  • Treat shock with immediate hemodynamic support.
  • Treat hypoglycemia.
  • Manage acute seizures.
  • Administer antidotes, e.g., naloxone for opioid overdose.
• Initiate protective measures, e.g.:
  • Airway protection
    • Basic airway maneuvers for all patients with at-risk airway features
    • Definitive airway for persistently ↓ LOC (e.g., GCS ≤ 8) or signs of complete airway obstruction [13]
  • C-spine immobilization for trauma
  • Neuroprotective measures for CNS injury, including ICP management for cerebral herniation syndromes
• Begin time-sensitive management steps: e.g., antibiotics for sepsis, reperfusion therapy for ischemic stroke

Next steps [2][8]

• Once the patient is stabilized, proceed with a full clinical and diagnostic evaluation.
• See the following management approaches for specific causes and/or manifestations of AMS:
  • ”Management of delirium”
  • ”Approach to the agitated or violent patient”
  • ”Approach to psychosis”
  • ”Approach to the poisoned patient”
  • ”Management of ischemic stroke” and “Overview of stroke”
  • “Moderate and severe TBI management”

Obtain EEG monitoring for patients with suspected nonconvulsive status epilepticus.

Critical causes include potentially rapidly reversible etiologies and conditions that may pose an imminent threat to life.

Perform diagnostic studies based on clinical evaluation in tandem with the initial management of AMS and coma. More thorough targeted diagnostics can be obtained once the patient is stabilized.

Routine laboratory studies [3][8][15]

• CBC: to evaluate for signs of infection, e.g., leukocytosis
• BMP: to evaluate for electrolyte imbalances, acidosis, and renal dysfunction
• Blood gases: to evaluate for hypercarbia, hypoxia, and acid-base imbalances
• Liver chemistries, albumin, INR: if hepatic encephalopathy is suspected
• Blood cultures: if infection is suspected
• Urine analysis: Consider including urine toxicology screen.
• Consider serum drug levels: e.g., acetaminophen, salicylates, ethanol.

ECG findings [3][8][15]

• Arrhythmia, including toxin-induced rhythm and conduction abnormalities
• ECG features of underlying structural heart disease
• ECG signs of elevated ICP

Neuroimaging [3][8][15]

• Indications
  • Focal neurological deficits
  • History of head injury
  • Unclear etiology of AMS or coma
  • Persistent AMS despite treatment or resolution of the suspected cause
• Initial modality: CT head without contrast [8]
• Advanced imaging: consider based on clinical suspicion
  • Acute ischemic stroke: CT or MR angiography
  • CNS infection, abscess, or tumor: CT head with and without contrast
  • Posterior fossa pathology: MRI brain [8]

Additional studies

May be indicated based on the clinical presentation and the suspected underlying etiology. For further information, see:

• “Symptom-based diagnostic workup for delirium”
• ”Toxicological risk assessment”
• “Diagnostics in TBI”
• “Diagnostic studies for secondary psychosis”
• “Diagnostics in agitated or violent patients.”

• Symptomatic therapy
  • Bladder catheterization for urinary retention [16]
  • Regular oral care
• Prevention of coma complications
  • Maintenance fluids as needed
  • Prevention of decubitus ulcers
  • NG tube placement for enteral nutrition and medication
    • Conscious patients with unsuccessful bedside swallow assessment: Establish NPO status and insert an NG tube.
    • Unconscious patients: Insert an NG tube if the underlying cause is not rapidly reversible.
  • Stress ulcer prophylaxis
  • VTE prophylaxis
  • Corneal protective measures for incomplete eyelid closure (e.g., taping, lubricant). [17]
• Prevention of iatrogenic complications
  • Prevention of catheter-associated UTIs
  • Prevention of intravascular catheter-related infections
  • Prevention of ventilator-associated infections
• Other: Initiate discussions of goals of care and/or end-of-life counseling with the surrogate decision-maker, if appropriate.

Depends on the site of initial assessment (e.g., ED vs. ward), clinical stability, expected course, and individual patient factors. [2]

• Consider ICU admission for patients requiring frequent monitoring, hemodynamic stabilization, and/or respiratory support.
• Consider urgent interfacility transfer for neurosurgical intervention if not available locally.
• Consider discharge home in patients with all of the following:
  • Identified and treated acute and reversible causes (e.g., hypoglycemia, opiate overdose)
  • Return to baseline mental status
  • Stability on observation
  • No other medical issues requiring inpatient treatment

In patients with altered mental status due to long-acting agents (e.g., opioid overdose from methadone, hypoglycemia from sulfonylureas), consider admission for observation even if the mental status has returned to baseline.

The following conditions can mimic coma. See “Causes of AMS and coma” for underlying etiologies.

• Conditions in which consciousness is preserved but the patient cannot produce voluntary movements or motor responses [4]
  • Locked-in syndrome
  • Neuromuscular paralysis: e.g., secondary to paralytic medications, botulism, or snake bites
  • Akinetic mutism
• Psychogenic unresponsiveness: an unresponsive state caused by an underlying psychiatric disorder [18]
  • Etiologies include mood disorders, psychotic disorders, factitious disorder, malingering
  • Clinical features include:
    • Stupor
    • Coma
    • Catatonia
    • Dissociation
    • Psychogenic nonepileptic seizures
  • Diagnosis based on typical examination findings, e.g.: [15]
    • Active resistance to eye opening
    • Purposeful diversion of the arm when held above the face and dropped