From the Guidelines
When evaluating a patient with acute onset altered sensorium, a noncontrast head CT is usually appropriate as the first-line neuroimaging test of choice to evaluate for a possible neurological source of their persistent altered mental status, as recommended by the American College of Radiology Appropriateness Criteria 1. This approach is essential in identifying potential life-threatening causes of altered sensorium, such as intracranial hemorrhage or stroke. A systematic evaluation should begin with a rapid assessment of vital signs, airway, breathing, and circulation. Perform a focused neurological examination including Glasgow Coma Scale, pupillary responses, and assessment for focal deficits. Laboratory tests should include:
- Complete blood count
- Comprehensive metabolic panel
- Blood glucose
- Arterial blood gases
- Toxicology screen
- Blood cultures if infection is suspected Specific tests for common causes include:
- Ammonia levels for hepatic encephalopathy
- Thyroid function tests
- Vitamin B1 levels if Wernicke's encephalopathy is suspected Neuroimaging with CT or MRI of the brain should be performed promptly to rule out structural causes like stroke, hemorrhage, or mass lesions. Lumbar puncture may be necessary if meningitis or encephalitis is suspected, examining CSF for cells, protein, glucose, and cultures. An electroencephalogram (EEG) is valuable for detecting seizure activity, particularly non-convulsive status epilepticus, as recommended by the Neurocritical Care Society and the European Society of Intensive Care Medicine 1. Additional tests may include HIV testing, autoimmune panels, and heavy metal screening depending on clinical suspicion. The yield of neuroimaging studies in patients with altered mental status is relatively low, with relevant abnormal findings in only 11% of cases, as reported in a recent meta-analysis 1. However, the potential benefits of early detection and treatment of life-threatening causes outweigh the risks, and a comprehensive approach allows for rapid identification of the underlying cause, which is crucial in guiding management and ensuring early appropriate triage.
From the Research
Tests for Acute Onset Altered Sensorium
The evaluation of acute onset altered sensorium involves a combination of clinical assessment, laboratory tests, and imaging studies. The following are some of the key tests used in the diagnosis of altered mental status:
- Blood glucose check: All protocols recommend a blood glucose check, with 21 (64%) suggesting treatment for adults with a blood glucose level <60mg/dL 2
- Toxicological treatment: Naloxone is recommended for signs of opioid overdose, with 13 (39%) protocols providing specific parameters 2
- Electrocardiogram: A 12-lead electrocardiogram is recommended by 8 (24%) protocols, while others suggest cardiac monitoring 2
- Supplemental oxygen: 14 (42%) protocols advise supplemental oxygen as needed, with 7 (21%) providing specific parameters 2
- Laboratory testing: Laboratory tests such as complete blood count, blood chemistry, and urinalysis can help identify underlying causes of altered mental status 3
- Chest radiography: Chest radiography can help diagnose infections and other systemic conditions 3
- Neuroimaging: Head computed tomography (CT) without contrast is the primary modality for evaluation of altered mental status, with MR imaging recommended in cases of negative CT but high clinical concern 4
- Lumbar puncture and electroencephalography: These tests are important in the evaluation of altered mental status, particularly when the initial evaluation does not identify a cause or raises concern for intracranial pathology 3
Diagnostic Approach
The diagnostic approach to altered mental status involves a comprehensive evaluation, including:
- History and physical examination: A thorough history and physical examination can help identify potential causes of altered mental status 3
- Identification of reversible causes: Clinicians should identify and treat reversible causes of altered mental status, some of which require urgent intervention to minimize morbidity and mortality 3
- Consideration of multiple etiologies: Altered mental status can have multiple etiologies, and clinicians should consider various causes, including infection, metabolic disturbances, toxin exposure, and psychiatric conditions 3