Curriculum · Neurology
Approach to altered mental status
What it is
Altered mental status is a general phrase describing the undifferentiated presentation of disorders of mentation, including impaired cognition, diminished attention, reduced awareness, and an altered level of consciousness. It is common: 5 to 10% of emergency department patients present with AMS, with rates of approximately 40% in the elderly population. Because the phrase covers so much, history and examination come first, and the differential is held open until then.
Causes and risk
The differential diagnosis is grouped in four.
- Primary neurologic: trauma, structural, infectious, and autoimmune or other.
- Metabolic: toxic, electrolyte, endocrine and hepatic.
- Infectious: central nervous system infections and severe systemic infections.
- Psychiatric: psychosis, catatonia and mania.
Hypertensive emergency belongs here twice over. Hypertensive encephalopathy gives altered mental status, headache, seizures, visual disturbance, nausea, vomiting and papilledema. Intracranial haemorrhage gives severe headache, dizziness, confusion, slurred speech, seizures, and body side weakness or numbness or other focal neurologic deficits.