What is the workup for altered mental status (AMS)?

From the Guidelines

The workup for altered mental status (AMS) should begin with a rapid assessment of vital signs and airway, breathing, and circulation (ABC) to ensure patient stability, followed by a thorough physical and neurological examination, and laboratory tests including complete blood count, comprehensive metabolic panel, blood glucose, arterial blood gases, toxicology screen, blood cultures, and urinalysis, as well as neuroimaging with CT or MRI of the brain to rule out structural causes, as recommended by the most recent guidelines 1. The initial evaluation should include a focused history from witnesses or family regarding onset, progression, and associated symptoms.

• Laboratory tests should be guided by clinical suspicion and may include:
  • Complete blood count
  • Comprehensive metabolic panel
  • Blood glucose
  • Arterial blood gases
  • Toxicology screen
  • Blood cultures
  • Urinalysis
• Neuroimaging with CT or MRI of the brain is essential to rule out structural causes, with a noncontrast head CT being the first-line neuroimaging test of choice in this setting, as it can be performed safely and rapidly in all patients 1. Additional studies may include:
• Electroencephalogram (EEG) to detect seizure activity
• Lumbar puncture if infection is suspected (after ruling out increased intracranial pressure)
• Specific tests based on clinical suspicion, such as ammonia levels for hepatic encephalopathy or thyroid function tests for endocrine disorders. This comprehensive approach is necessary because altered mental status has numerous potential causes, including metabolic derangements, infections, toxins, structural brain lesions, and systemic illnesses, and early identification of the underlying cause is critical for appropriate management and improved outcomes, as delayed treatment can lead to permanent neurological damage or death 1.

From the Research

Initial Assessment

The workup for altered mental status (AMS) involves a comprehensive evaluation to identify the underlying cause. The initial priorities are to ensure a clear airway, and that breathing and circulation are adequate 2.

Clinical Evaluation

The Glasgow Coma Scale (GCS) is a useful tool in assessing the level of consciousness and predicting outcomes in patients with altered sensorium 3, 4. A lower GCS score is associated with a higher risk of poor outcomes, including death 4.

Laboratory Investigations

Laboratory tests, such as complete blood counts, blood chemistry, and serum osmolality, can help identify potential causes of altered sensorium, such as diabetic ketoacidosis 3. In patients with diabetic ketoacidosis, systolic blood pressure <90 mmHg, calculated effective serum osmolality >320 mosmol/Kg, uncorrected serum sodium >150 mmol/L, and white blood cell count >25 x 10^6/L are independently associated with altered sensorium 3.

Neuroimaging and EEG

Neuroimaging studies, such as computed tomography (CT) or magnetic resonance imaging (MRI), may be necessary to rule out structural causes of altered mental status, such as stroke or intracranial hemorrhage. Electroencephalography (EEG) can help diagnose seizures or status epilepticus, which can cause altered sensorium 5. Continuous EEG (cEEG) monitoring provides independent prognostic information in patients with altered sensorium and suspected seizures, and unfavorable findings include nonconvulsive seizures, periodic epileptiform discharges, and abnormal background 5.

Management

The management of altered mental status depends on the underlying cause. In some cases, acute interventional therapy, such as mechanical thrombectomy, may be necessary to treat conditions like basilar artery occlusion 6. In patients with fever and altered sensorium, the Glasgow Coma Score can predict poor outcomes, and prompt treatment of the underlying cause, such as bacterial meningitis or viral encephalitis, is essential 4.

Key Findings

• The initial assessment of altered mental status involves ensuring a clear airway, breathing, and circulation 2.
• The Glasgow Coma Scale is a useful tool in assessing the level of consciousness and predicting outcomes 3, 4.
• Laboratory investigations, such as complete blood counts and blood chemistry, can help identify potential causes of altered sensorium 3.
• Neuroimaging and EEG can help diagnose structural causes or seizures 5, 6.
• The management of altered mental status depends on the underlying cause, and prompt treatment is essential to improve outcomes 6, 4.