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Altered mental status (AMS) represents a spectrum of cognitive impairment ranging from confusion and disorientation to coma, characterized by changes in consciousness, attention, cognition, or perception from baseline function. It is a common presenting complaint in emergency medicine that requires systematic evaluation to identify underlying reversible causes. AMS can result from numerous etiologies including metabolic disturbances, infections, toxins, structural brain lesions, and psychiatric conditions.
AMS occurs when there is disruption of the reticular activating system in the brainstem, diffuse cortical dysfunction, or interference with neurotransmitter systems that maintain normal consciousness and cognition. Common mechanisms include hypoxia, hypoglycemia, electrolyte imbalances, toxin exposure, inflammatory processes, or direct structural damage to brain tissue. The brain's high metabolic demands make it particularly vulnerable to systemic disturbances that affect oxygen delivery, glucose availability, or cellular metabolism.
The approach to AMS involves rapid assessment of airway, breathing, and circulation followed by point-of-care glucose testing and consideration of naloxone if opioid overdose is suspected. A systematic evaluation using frameworks like 'VITAMIN-D' (Vascular, Infectious, Trauma, Autoimmune, Metabolic, Intoxication, Neoplastic, Degenerative) helps identify treatable causes. Key diagnostic studies typically include complete blood count, comprehensive metabolic panel, arterial blood gas, urinalysis, and neuroimaging when indicated, with treatment directed at correcting underlying pathophysiology while providing supportive care.