Clinical features of confusional states

Confused patients need to be assessed repeatedly. Delirium can be diagnosed if the patient shows several features during parts of the evaluation process. The mental activities altered in confusional states are listed in Table 1.. Three domains (i.e. attention, orientation, and memory) are typically impaired in delirious patients;

other features are more variable.

Table 1 Mental activities altered in delirium (confusional state)

Attention deficits can be regarded as the sine qua non of confusional states. The patient is easily distracted and cannot maintain his or her focus of attention during a task. Inattention and distractability are often easily observed during the interview. In less obvious cases, inattention can be assessed at the bedside by asking the patient to name the months of the year in reverse order or to repeat several numbers in sequence.

Memory and orientation are typically impaired, at least in part, because of attention deficits. Memory deficits are readily apparent when the patient is asked to encode new information, for example to recall three words, either immediately or after a delay of 5 min. The patient may also show deficits in the recall of previously encoded information. Some patients will be partially or completely amnestic for the delirious episode.

Impaired orientation is the third main feature of confusional states. Except for lucid intervals, delirious patients are typically disoriented with regard to time and to place, but rarely to person.

Thinking is often altered in acute confusional states. Such patients are disorganized, irrational, and manifest impaired reasoning. Thinking can be grossly impaired; delusions and paranoia may develop. Poor insight and judgment about medical treatment often make decision-making impossible. Simple tests of reasoning can be quite helpful. For example, the patient is asked to explain the following story: 'I have a friend named Frank Jones. His feet are so big that he has to put his pants on over his head. Can Mr. Jones do that?' The patient may explain that the story is impossible (i.e. cortical function intact), respond with humor (i.e. limbic understanding of the absurdity of the story), or show no reaction. The delirious patient often responds with a smile but lacks a clear understanding of the story.

Altered perception in the form of illusions or, less often, hallucinations is seen in some confusional states. Visual hallucinations are more common than auditory or tactile hallucinations. Confusional states secondary to sedative-hypnotic withdrawal are more likely to present with hallucinations.

Several additional features are seen in some confused patients. For example, the hyperactive confused patient with delirium tremens displays increased arousal, labile affect, and decreased sleep, whereas the hypoactive confused patient with hepatic encephalopathy shows decreased arousal, flat affect, and increased sleep (to the degree of somnolence or coma).

Neurological signs such as tremor, myoclonus, or asterixis are seen in some types of delirium (e.g. hepatic encephalopathy). Other deficits such as impaired constructional ability, word-finding difficulties (dysnomia), or writing disturbances (dysgraphia) are more generally found. The clock-drawing test often provides a rapid screen for the presence and degree of delirium. Dysgraphia, which is easily tested by asking the patient to write a sentence, is a very sensitive, albeit non-specific, test for delirium.

Several rating scales are now available for the efficient and reliable assessment of acute confusional states ( Wise and Gray 1994). These are particularly helpful when repeated assessments of a patient are performed by different observers.

If the patient displays the clinical features seen in acute confusional state, i.e. delirium, it is important to investigate the duration, rapidity of onset, and course over time. The differential diagnosis of acute confusional states includes chronic conditions of impaired brain function that lead to similar cognitive deficits. For example, functional psychosis, dementia, and depression show many of the features seen in delirium, but do not show the fluctuation and clouding of consciousness.

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