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 knowledge of the patient’s background and underlying medical illnesses. It is our view that such patients should be admitted to a general medical or neurologic ward. Transfer of the patient to a psychiatric service is undertaken only if the behavioral disorder proves impossible to manage on a general hospital service.
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 and relationships. The following nomenclature has proved useful and is employed in this and subsequent chapters.
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 denoting reduced power of concentration, accompanied usually by disorientation—which may be manifest or is demonstrated only by direct questioning—inability to properly 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. 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 and accompanying visual and auditory illusions or hallucinations are variable features that may be appended to the picture. 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 try to retain the term delirium to describe a special activated state of agitation, hallucinations, and sometimes tremulousness, which is invariably accompanied by the confusional state. Also, as pointed out in Chap. 16 on coma, a confusional state may appear at any stage in the evolution and resolution of a number of diseases that lead to drowsiness, stupor, and coma—typically in the metabolic encephalopathies but also in diseases affecting those parts of the brain that maintain normal arousal.
Confusion is also a characteristic feature of the chronic syndrome of dementia, where it is ultimately the product of failure of cognition, language, memory, and other intellectual functions; there it is the long-standing and progressive nature of the mental confusion that differentiates dementia from the acute confusional and delirious states that carry quite different implications. Finally, intense emotional disturbances, of either manic or depressive type, may interfere with attentiveness and coherence of thinking and thereby produce an apparent confusional state.
Restricted forms of what could be called a type of confusion appear as a result of certain focal cerebral lesions, particularly of the frontal, parietal, and temporal lobe association areas. Then, instead of a global inattention and incoherence, there are specific and circumscribed syndromes, such as unilateral neglect of self or of the environment, inability to identify persons or objects, and sensorimotor defects as described in Chap. 21. Yet another special form of confusion arises as a result of disordered language function, which also alters the stream of thought; this aphasia is a consequence of lesions in the language areas of the left temporal lobe. These are considered separately in Chap. 22.