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A confusional state, sometimes referred to as encephalopathy or delirium, is a state 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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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 should establish the time course of the disorder and provide clues to its nature and cause. Confusional states are acute to subacute in onset, whereas dementias are chronic disorders. In either case, a relative or friend may be the best source of information about the patient’s previous level of functioning, the time when dysfunction became evident, and the nature of observed changes.
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Preexisting conditions that predispose to confusional states should be noted, such as alcoholism (intoxication or withdrawal, or Wernicke encephalopathy), other drug abuse (intoxication ...