Functional disorders

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.

Non-epileptic attacks or pseudoseizures

Non-epileptic attacks or pseudoseizures are episodes that appear superficially to be seizures. They may be continuous and mimic status epilepticus; indeed, 50% of patients admitted to intensive care units with status epilepticus have been found to have pseudoseizures. In many patients, the attacks can readily be distinguished from epileptic seizures: they often include semi-purposeful thrashing (‘it took five men to keep me down’); patients remain pink throughout and may flush, but do not become cyanosed; respiration is normal; they do not bite their tongues; incontinence is rare; and recovery is usually quick. There are some patients where it is more difficult to be certain. To establish the diagnosis, an EEG during the attack needs to be demonstrated to be normal. The attacks tend to occur more often when medical and nursing staff are at hand and obtaining an EEG during an attack is usually more readily achieved than in epileptic seizures. Measurement of prolactin following a seizure can also be useful, as this is elevated after a tonic-clonic epileptic seizure.

It is uncertain how many patients with pseudoseizures also have epileptic seizures.

It is important to consider this diagnosis to avoid potential iatrogenic injury to the patient, who may be considered for intubation and ventilation when there is no response to anticonvulsants, and from the adverse effects of multiple anticonvulsants.

Paralysis

In patients with non-organic weakness, there is usually an inconsistency in the power of the limb on formal testing and when the patient uses it. Examples include patients who can swing their legs up only on the bed when getting onto it but cannot lift the legs against gravity on formal testing; or patients who can stand with legs slightly flexed at the knees supporting their own weight but who cannot walk. There is usually a characteristic collapsing weakness. There are several manoeuvres that can bring this out, such as Hoover’s sign (Fig. 1), or the movement found when testing coordination, which is not obtained on testing power.

Fig. 1 Hoover’s sign. (a) The patient is unable to extend the hip and to press the heel into the bed on request. (b) The hip is extended involuntarily when the opposite leg is lifted off the bed.

Sensory loss

Most patients with organic sensory loss have an incomplete loss, which affects some modalities more than others and accords with a recognizable pattern (p. 60). In patients with non-organic loss, the loss is often complete, affecting all modalities and in a distribution that does not conform to an anatomical sensory distribution. There are often inconsistencies on repeat testing. There is usually a discrepancy in the functional loss associated with the sensory loss, for example an arm apparently without joint position sense can still touch the nose with eyes shut or reliably touches the same spot just to one side of the nose.

Sensory loss is often elaborated, so that a mild organic loss is extended in distribution and severity.

Visual loss

This can occur in a wide range of different patterns, and in each there is a range of differential diagnoses that need careful consideration. Signs that prove useful are the finding of a ‘tube’ field loss that does not broaden as it gets further from the eye (Fig. 2).

Fig. 2 Tube visual field is a constant size regardless of distance from the eye.

Physiologically-induced sensations and physical symptoms of anxiety

Other types of symptom that fall within somatization are physiologically-induced bodily sensations and the physical symptoms of anxiety.

The symptoms associated with hyperventilation account for 2% of neurological outpatients. These symptoms are dizziness or lightheadedness, tingling in the hands, feet and around the mouth, some visual disturbance and sometimes loss of consciousness. Breath-holding time is reduced and forced hyperventilation reproduces the symptoms. Treatment with retraining of breathing by physiotherapists is usually successful.

Anxiety is commonly associated with hyperventilation and many of the physical symptoms attributed to anxiety could be mediated by this mechanism. In addition, patients may be aware of a tremor; sometimes they describe ‘a shaking inside’. Recognition of the condition and treatment with anxiolytics is usually successful.

Chronic fatigue syndrome

This syndrome of uncertain aetiology is subject to considerable controversy. The presentation is with disabling fatigue that has lasted for over 6 months where no other medical cause has been found. Symptoms usually include sore throats, low-grade fever, joint and muscle pains, headache, poor concentration and sleep disturbance. Many patients have features of depression. It is more common in women.

The aetiology of chronic fatigue syndrom is much disputed. No organic, especially infective, cause has been found. There are many features in common with other somatization disorders such as fibromyalgia, irritable bowel, etc.

Treatments that have been shown to be effective in clinical trials include tricyclic antidepressants, graded exercises and cognitive behavioural therapy.

Fibromyalgia

In these patients, there is a prominent muscle aching, often with fatigue, arthralgia, malaise, sleep disturbance and headaches. There are no definite abnormalities on examination, though some muscles are tender. The reproducibility of these so-called ‘trigger points’ is contentious. This condition, like chronic fatigue syndrome, probably represents a somatization disorder. Treatment is as for chronic fatigue syndrome.

Functional disorders

A significant proportion of patients in neurological clinics or on neurological wards have symptoms or signs that cannot be explained by organic disease.

Investigation is aimed at excluding underlying neurological disease.

Characteristic syndromes include pseudoseizures, weakness and sensory and visual loss.

Treatment is difficult; cognitive therapy may help.