Functional disorders

Published on 10/04/2015 by admin

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Last modified 10/04/2015

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Functional disorders

There are many neurological patients with neurological symptoms and signs that are not due to underlying neurological abnormalities but reflect a psychological problem. In others, there is an elaboration of a neurological abnormality so that the signs elicited extend beyond the distribution of the neurological lesion or are out of proportion with the neurological lesion.

There is considerable debate about the diagnoses, classification and terminology used in this area of neurology. Terms commonly used are non-organic, functional, psychogenic or hysterical, though alternatives such as somatiform disorders or abnormal illness behaviour and medically unexplained symptoms have recently been proposed. These terms have been used in different ways by different neurologists.

The term somatization has been defined as ‘the expression of distress in the idiom of bodily complaints’. This is an umbrella term which includes diagnoses (such as hysteria), with the notion of an unconscious trigger for the symptoms, and patients with anxiety or depression with unexplained somatic symptoms. The term ‘medically unexplained symptoms’ can be useful as a neutral term that does not postulate a cause for the symptoms.

These disorders, however named, are very important, being a significant factor in up to 20% of neurological outpatients and up to 40% of neurological admissions. There are a large number of different physical manifestations. However, there are several typical clinical syndromes, and they tend to affect patients with some particular features.

Clinical approach

The clinical approach must first determine if there is an underlying organic disease, assess its contribution to the clinical presentation and try to make a positive psychiatric diagnosis. This has been aided by the newer investigative and imaging techniques. How this is done will depend on the clinical presentation. There is always a concern that there is an underlying neurological condition hidden beneath the elaboration.

However, there are some ‘classical’ features. These include an effect of ‘belle indifférence’, where the patient seemingly is unconcerned about the disability, and a collapsing weakness, where the power just suddenly gives. These are not specific findings; the latter is also a feature of conditions such as myasthenia gravis and the early stages of Guillain–Barré syndrome (when hysteria is the most commonly given erroneous differential diagnosis).

Non-organic syndromes occur more commonly in women, and usually in younger patients. It is a diagnosis that is made only with great caution in older patients. There is often a history of other physical symptoms and there may be a history of deliberate self-harm or drug overdose.

The management of patients with somatization disorders is difficult once the diagnosis is established. Associated psychiatric illnesses such as anxiety and depression need to be identified and treated. Psychological interventions, including cognitive therapy to try to reattribute the physical symptoms, have been beneficial in some cases. Physiotherapy can be useful in helping a patient to overcome a non-organic paralysis.

In some patients, there is a conscious fabrication of a neurological deficit. This is malingering. There are usually more clear-cut financial or other benefits to the patient.

The most common syndromes seen are discussed below.

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