What is the initial approach to evaluating a patient with altered mental status?

Initial Approach to Evaluating a Patient with Altered Mental Status

The initial approach to evaluating a patient with altered mental status must begin with assessment and stabilization of ABCs (Airway, Breathing, Circulation) followed by immediate evaluation for life-threatening reversible causes while monitoring vital signs. 1

Primary Assessment (Immediate Actions)

1. Stabilize the patient:

   • Assess and secure airway, breathing, and circulation
   • Monitor vital signs (temperature, pulse, blood pressure, respiratory rate, oxygen saturation)
   • Establish IV access
   • Check blood glucose (immediate intervention for hypoglycemia)

2. Rapid neurological assessment:

   • Glasgow Coma Scale (GCS) score
   • Pupillary response and size
   • Motor function and reflexes
   • Signs of meningeal irritation (nuchal rigidity, Kernig's sign, Brudzinski's sign)

Secondary Assessment (First 30-60 minutes)

Essential Laboratory Tests:

• Complete blood count
• Basic metabolic panel
• Liver function tests
• Blood glucose
• Urinalysis
• Blood cultures (if febrile)
• Thyroid function tests (especially in elderly)
• Ammonia levels (if liver dysfunction suspected)
• Toxicology screen (when appropriate)

Neuroimaging:

• Non-contrast head CT is appropriate for initial imaging in patients with suspected intracranial pathology or focal neurologic deficit 2
• MRI brain may be considered when CT is negative but clinical suspicion remains high

Additional Evaluation:

• Electrocardiogram
• Chest X-ray (to assess for pneumonia or other systemic illness)
• Lumbar puncture (if CNS infection suspected and no contraindications)
• EEG (if seizure activity suspected, particularly nonconvulsive status epilepticus)

Systematic Approach to Identifying Causes

The most common causes of altered mental status include 1, 3:

1. Neurological (35%)
2. Toxicological (23%)
3. Systemic/organic (14.5%)
4. Infectious (9.1%)
5. Endocrine/metabolic (7.9%)
6. Psychiatric (3.9%)
7. Traumatic (2.1%)

Mnemonic for Evaluation: "AEIOU TIPS"

• A: Alcohol, Acidosis
• E: Electrolyte disturbances, Endocrine disorders
• I: Insulin (hypoglycemia), Infection
• O: Oxygen (hypoxia), Opiates
• U: Uremia
• T: Trauma, Temperature (hypo/hyperthermia), Toxins
• I: Infection, Intracranial causes (stroke, hemorrhage)
• P: Psychiatric, Poisoning
• S: Seizures, Shock, Space-occupying lesions

Management Principles

1. Treat life-threatening conditions immediately:

   • Administer glucose for hypoglycemia
   • Provide oxygen for hypoxia
   • Give naloxone for opioid overdose
   • Administer thiamine before glucose in suspected Wernicke's encephalopathy
   • Treat seizures promptly with appropriate antiseizure medications

2. Address underlying causes:

   • Antibiotics for suspected infections after cultures
   • Lactulose for hepatic encephalopathy
   • Correction of metabolic derangements
   • Discontinuation of offending medications

3. Provide supportive care:

   • Maintain normothermia
   • Ensure adequate oxygenation and perfusion
   • Avoid physical restraints when possible
   • Implement reorientation strategies

Common Pitfalls to Avoid

1. Attributing behavioral changes to psychiatric causes without adequate medical workup 1
2. Overreliance on neuroimaging before basic laboratory testing
3. Missing atypical presentations of common infections in elderly patients
4. Failure to recognize medication side effects or interactions
5. Routine CT scanning without clinical indication - the yield of neuroimaging in patients with AMS is low (only 11% have relevant abnormal findings) 2

Special Considerations

• Elderly patients: Consider additional tests for B12 deficiency and thyroid disorders 1
• Febrile patients: Lower Glasgow Coma Scale, presence of lateralizing signs, higher systolic blood pressure, and lower body temperature are associated with abnormal brain imaging 2
• Patients with psychiatric history: Still require thorough medical evaluation as medical causes can present with psychiatric symptoms 2
• Patients with delirium: Prevalence in ED ranges from 7-35%; strong associations include nursing home residence, cognitive impairment, hearing impairment, and history of stroke 2

The history and physical examination remain the most diagnostically valuable components of the evaluation, with 51% and 41% yield respectively, while laboratory and radiographic studies have lower diagnostic yields 4.