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Key Points

  • Do not delay bedside glucose determination, administration of glucose, and naloxone, if indicated. These interventions may prevent the need for endotracheal intubation.

  • Talk to the paramedics and family; they can often identify the cause of altered mental status (AMS).

  • Identify level of AMS, systemic conditions, and any focal deficits with the physical examination.

  • Re-examine your patients frequently and note any changes in condition and response to therapy.


Altered mental status (AMS) may have an organic (ie, structural, biochemical, pharmacologic) or functional (ie, psychiatric)cause. AMS accounts for 5% of emergency department (ED) visits. About 80% of patients with AMS have a systemic or metabolic cause, and about 15% have a structural lesion.

Consciousness has 2 main components: arousal and cognition. Arousal is controlled by the ascending reticular activating system (ARAS) in the brainstem. Cognition is controlled by the cerebral cortex. Lethargy, stupor, obtundation, and coma are imprecise terms used to describe alterations of arousal. A description of the patient's arousal level (eg, opens eyes to voice) is preferable. Delirium is an alteration of both arousal and cognition. Patients exhibit restlessness, agitation, and disorientation. Dementia is an alteration of cognition, not arousal.

ARAS is a complex system of nuclei in the brainstem. It may be impaired by small structural lesions in the brainstem such as ischemic or hemorrhagic stroke, shear forces from head trauma, or external compression from brain herniation. Severe toxic and/or metabolic derangements (eg, hypoxia, hypothermia, drugs) can also cause impairment. Bilateral cerebral cortex dysfunction must occur to cause decreased levels of arousal or profound AMS. This is usually caused by toxic/metabolic derangements, infection, seizures, subarachnoid hemorrhage (SAH), or increased intracranial pressure (ICP). Unilateral lesions such as stroke do not by themselves cause profound AMS.

Clinical Presentation


AMS represents a spectrum of disease presentations from profoundly depressed arousal requiring emergent intubation to severe agitation and confusion requiring restraint and sedation. Initial stabilizing measures are often needed before a complete history and physical examination can be performed.

If the patient is unable to give a coherent history, alternate sources of history should be sought. Prehospital providers should be questioned about the patient's condition in the field, therapies given and the response, and the condition of the home environment (eg, pill bottles, suicide note). Family members should be contacted to ascertain past history of similar episodes, medical history, trauma, substance abuse, and the last time the patient was seen in a normal state. The patient's belongings should be searched for medical identification bracelets, pill bottles, phone numbers, or other potential sources of information.

Patients presenting to the ED with AMS often include the elderly, who are more prone to infection, have comorbid illnesses, and take multiple medications; substance abusers (eg, heroin, cocaine, alcohol withdrawal, and liver failure); ...

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