Scope of the problem
The patient with altered mental status (AMS) represents a great challenge for emergency physicians: potential life threat, rapid decision-making and astute detective work. The etiology might be chronic or acute, life-threatening or benign, reversible or irreversible. One of nearly a dozen different organ systems might be implicated or perhaps harmed by the event. The knowledgeable, diligent emergency physician will be able to narrow the differential to a manageable number of diagnoses within minutes and correctly treat the majority of patients.
AMS is an alteration of a patient's level of cognitive (knowledge-related) ability, appearance, emotional mood, and speech and thought patterns.
Level of consciousness relates to one's level of awareness and responsiveness to his or her surroundings.
Lethargy is generally referred to when one is suffering from a mild to moderate depression in level of consciousness. It implies an abnormal state of drowsiness or sleepiness in which it may be difficult to arouse the patient.
Stupor is a more profound depression of one's level of consciousness. One might say that stupor is an extreme form of lethargy requiring a greater stimulus to produce a lesser degree of arousal.
Coma is an abnormal state of deep unconsciousness from which a patient cannot be awakened.
Organic illness refers to impairment of normal anatomic and/or physiological activity resulting in impaired mental functioning. Functional illness generally refers to a physical disorder with no known or detectable organic basis to explain the symptoms.