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The striking state in which a patient with previously intact mentality becomes confused is observed daily on the medical, surgical, and emergency services of a general hospital. Occurring, as it often does, during an infection with fever or in the course of a toxic or metabolic disorder such as renal or hepatic failure, or as an effect of medication, drugs, or alcohol, it never fails to create problems for the physician, nurses, and family. The physician has to cope up with the problem of diagnosis, often without the advantage of a lucid history, and any program of therapy is constantly impeded by the patient’s inattention, agitation, sleeplessness, and inability to cooperate. Nurses are burdened with the need to provide satisfactory care and a safe environment for the patient, and at the same time, maintain a tranquil atmosphere for other patients. The family must be supported as it faces the frightening prospect of a deranged mind with peculiar behaviors and all it signifies.

These difficulties are magnified when the patient arrives in the emergency ward, having behaved in some irrational way, and the clinical analysis must begin without the knowledge of the patient’s background and underlying medical illnesses.


The definition of normal and abnormal states of mind is difficult because the terms used to describe them have been given so many different meanings in both medical and nonmedical writings. Compounding the difficulty is the fact that the pathophysiology of the confusional states and delirium is not fully understood, and the definitions depend to some extent on their clinical causes. The following nomenclature has proved useful and is employed in this and subsequent chapters and is used in Chap. 16 on Coma and Related Disorders of Consciousness.

Confusion is a general term denoting the patient’s incapacity to think with customary speed, clarity, and coherence. Its most conspicuous attributes are impaired attention and reduced power of concentration, accompanied usually by disorientation, which may be manifest or is demonstrated only by direct questioning, inability to register immediate events and to recall them later, a reduction in the amount and quality of all mental activity including the normally constant inner ideation, and sometimes by the appearance of bewilderment (as often, there is lack of insight about one’s own confusion). Thinking, speech, and the performance of goal-directed actions are less affected but are nevertheless impersistent or abruptly arrested by the intrusion of the slightest external stimulus. Reduced perceptiveness to visual and auditory stimuli may be accompanied by illusions or hallucinations. This is what may be termed the global confusional state.

These disturbances appear in many contexts. The medical and psychiatric literature has adopted the term delirium to describe all confusional states (discussed further on). We have tried to retain the term delirium to describe a special activated confusional state of agitation, visual hallucinations, and tremulousness. The ...

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