Psychiatry

Published on 03/03/2015 by admin

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Last modified 03/03/2015

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16 Psychiatry

Delirium (see also p. 153)

Delirium is the most commonly misdiagnosed psychiatric disorder in the general hospital and many cases go undetected. Yet it is the most common psychosis met in the hospital setting; 10–20% of surgical and medical inpatients have delirium during their admission. It is the best indication that the higher centres of the brain are failing.

How would you diagnose delirium?

An acute onset and fluctuating course is valuable diagnostically. Delirium represents an acute generalised impairment of cognitive function (see Information box). The primary feature is disorientation in time and place (more rarely person). A well patient should know the day of the week, month and year (people who are well can occasionally get the date and time wrong). They should know that they are in hospital, its name and location, and the name of the ward. Other psychoses do not affect orientation.

Drug therapy

Doses of tranquillising drugs should start low and be titrated depending on age (this patient is 68 years old), pre-existing brain damage and response to initial treatment. Patients with delirium are often sensitive to medication and the dose needs to be balanced carefully.

If intramuscular medication is required

These drugs should not be given intravenously. If the patient is sensitive to medication and extrapyramidal side effects (EPSEs) are likely or present, use an ‘atypical’ anti-psychotic drug, such as risperidone (starting at 0.5 to 1 mg orally). Check doses carefully. Reversal of acute EPSEs can be achieved with a low dose of an anti-muscarinic drug (e.g. procyclidine 5 mg oral/IM).

Drugs and poisons as causes of delirium

Delirium can occur in response to excessive or normal doses of many drugs, particularly in the elderly. Some drugs are more likely to cause delirium than others.

Drugs causing delirium

Drugs with anti-muscarinic properties (common cause of delerium)

Drug withdrawal

Dementia

See also p. 156.

Dementia is the most common organic brain syndrome seen in elderly inpatients; 7% of people over the age of 65 and up to 33% over the age of 85 have a dementing illness. Treatable causes can be found in 10% of patients with definite dementia, but that figure is considerably higher if the ‘pseudodementia’ of depressive illness is included.

Dementia is a global, acquired, progressive deterioration of intellect, memory and personality. Altered (‘clouded’) consciousness is not usually involved, in contrast to delirium, although dementia is often an underlying predisposition for delirium (see p. 515).