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A confusional state, also referred to as encephalopathy or delirium, is a condition in which the level of consciousness is depressed, but to a lesser extent than in coma (unarousable unresponsiveness; see Chapter 3, Coma). In confusional states, responses to stimulation are at least semi-purposeful, whereas in coma, patients fail to respond to even painful stimulation or do so only in reflex fashion. Thus, the difference between a confusional state and coma is largely one of degree, and the causes overlap extensively.
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APPROACH TO DIAGNOSIS
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Evaluation of a patient with altered consciousness is aimed first at characterizing the nature of the disorder (confusional state, coma, or a more chronic condition, such as dementia) and second at determining the cause.
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A confusional state is most readily distinguished from dementia by the time course of impairment: confusional states are acute or subacute in onset, typically developing over hours to days, whereas dementia is a chronic disorder that evolves over months or years.
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Certain causes of confusional state must be identified urgently because they may lead rapidly to severe structural brain damage or death, which prompt treatment can prevent: examples include hypoglycemia, bacterial meningitis, subarachnoid hemorrhage, traumatic intracranial hemorrhage, and Wernicke encephalopathy (Table 4-1).
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History of Present Illness
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The history is important for establishing the time course of the disorder and can also provide clues to its nature and cause. A relative or friend may be the best source of information about the patient’s previous level of functioning, the time when dysfunction began, and the nature of the observed changes.
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Preexisting conditions that predispose to confusional states should be noted, such as alcoholism (intoxication, withdrawal, or Wernicke encephalopathy), other drug abuse (intoxication or infection), diabetes (hypo- or hyperglycemia), heart disease (stroke), epilepsy (seizures ...