Components of Consciousness

Causes of Altered Mental Status

History

Rate of onset

Abrupt: CNS

Gradual: Systemic

Physical Examination

• Vital Signs
  • Blood Pressure: low (shock), high (SAH, stroke, ICP)
  • Heart Rate: low (medication overdose, conduction block), high (hypovolemia, infection, anemia, thyrotoxicosis, drug/toxin)
  • Temperature: low/high (infection, drug/toxin, environmental)
  • Respiratory Rate: low/high (CNS, drug/toxin, metabolic derangement)
• Eyes
  • Unilateral dilation: CNS/structural cause
  • Papilledema: ICP
  • EOM: cranial nerve dysfunction
  • Oculocephalic: brainstem function
• Head: trauma
• Mucous membranes: hydration, laceration
• Neck: meningeal irritation
• Pulmonary: respiratory effort
• CV: murmur, arrhythmia, CO
• Abdomen: pulsatile mass, sequelae of liver failure
• Skin: rash, needle tracks

Labs

• Glucose
• ECG: arrhythmia, ischemia, electrolyte abnormalities
• BMP: electrolytes, renal failure, anion gap
• ABG: hypoxemia, hypercarbia
• Urinalysis: infection, SG
• Utox
• CBC: leukocytosis, leukopenia, severe anemia, thrombocytopenia
• Ammonia: hepatic encephalopathy
• TFT: thyrotoxicosis, myxedema coma
• CSF: meningitis, encephalitis

Imaging

• CT head: Non-contrast sufficient to identify ICH. Use contrast if mass/infection suspected
• CTA head/neck: If aneurysm, AVM, venous sinus thrombosis or vertebrobasilar insufficiency suspected
• CXR: PNA

References

1. Bassin, B., & Cooke, J. (2013). Depressed Consciousness and Coma. In Rosen’s Emergency Medicine – Concepts and Clinical Practice (8th ed., Vol. 1, pp. 142-150). Elsevier Health Sciences.