What is the cause of this patient's altered mental status, and what is the appropriate workup?

From the Guidelines

A complete altered mental status workup should begin with a rapid assessment of airway, breathing, and circulation, followed by a point-of-care glucose check and administration of thiamine 100mg IV, glucose 50% 50mL IV (if hypoglycemic), and naloxone 0.4-2mg IV/IM/intranasal (if opioid overdose is suspected) as recommended by the most recent guidelines 1.

Initial Assessment

The initial assessment should focus on identifying potential life-threatening causes of altered mental status, such as hypoglycemia, hypoxia, or opioid overdose. Vital signs, including temperature, should be obtained immediately. The history should focus on onset, medication use (especially sedatives, narcotics, and anticholinergics), substance use, and recent trauma or illness.

Physical Examination

Physical examination should include a complete neurological assessment using the Glasgow Coma Scale, pupillary responses, and checking for signs of trauma, meningeal irritation, and focal neurological deficits. Validated assessment scales, such as the Richmond Agitation Sedation Scale, may be employed to objectively quantify the severity of symptoms 1.

Laboratory Studies

Laboratory studies should include:

• Complete blood count
• Comprehensive metabolic panel
• Urinalysis
• Toxicology screen
• Blood cultures (if infection suspected)
• Arterial blood gases
• Ammonia levels (if liver disease suspected)
• Thyroid function tests

Imaging Studies

Imaging studies typically include a non-contrast head CT to rule out hemorrhage, stroke, or mass lesions. Additional studies may include:

• Lumbar puncture (if meningitis/encephalitis is suspected)
• EEG (for suspected seizures)
• MRI for more detailed brain imaging

Tailoring the Workup

The workup should be tailored based on the clinical scenario, with the goal of rapidly identifying and treating reversible causes of altered mental status such as hypoglycemia, hypoxia, drug overdose, infection, or intracranial pathology. The most recent guidelines emphasize the importance of early detection and accurate diagnosis of delirium, which is considered a medical emergency 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Complete Altered Mental Status Workup

To complete an altered mental status workup, the following steps should be taken:

• Identify the underlying cause of the altered mental status, which can be due to various etiologies such as systemic infections, metabolic derangements, or primary neurologic insults 2, 3, 4, 5
• Perform a primary survey followed by a secondary survey with special attention to immediate life-threatening reversible causes 4
• Conduct a systems-based approach to search for any other life-threatening or reversible causes 4
• Obtain a detailed history and physical exam, as well as laboratory and radiographic testing, including:
  • Laboratory testing to diagnose infections, metabolic disturbances, toxins, and systemic conditions 5
  • Chest radiography and electrocardiography to diagnose infections and systemic conditions 5
  • Neuroimaging with computed tomography or magnetic resonance imaging to diagnose intracranial pathology 5
  • Lumbar puncture and electroencephalography to diagnose certain conditions 5
• Consider the potential precipitating factors for the recent onset of altered mental status, including:
  • Primary central nervous system insults 5
  • Systemic infections 5
  • Metabolic disturbances 5
  • Toxin exposure 5
  • Medications 5
  • Chronic systemic diseases 5
  • Psychiatric conditions 5
• Identify and treat reversible causes of the altered mental status, and provide preventive measures for patients at increased risk 5
• Consider the importance of searching for causes of altered mental status in patients with cirrhosis, as mortality rates are higher in these patients 6