Elsevier

The Lancet Neurology

Volume 11, Issue 3, March 2012, Pages 250-260
The Lancet Neurology

Review
Functional (psychogenic) movement disorders: merging mind and brain

https://doi.org/10.1016/S1474-4422(11)70310-6Get rights and content

Summary

Functional (psychogenic) movement disorders (FMD) are part of the wide spectrum of functional neurological disorders, which together account for over 16% of patients referred to neurology clinics. FMD have been described as a “crisis for neurology” and cause major challenges in terms of diagnosis and treatment. As with other functional disorders, a key issue is the absence of pathophysiological understanding. There has been an influential historical emphasis on causation by emotional trauma, which is not supported by epidemiological studies. The similarity between physical signs in functional disorders and those that occur in feigned illness has also raised important challenges for pathophysiological understanding and has challenged health professionals' attitudes toward patients with these disorders. However, physical signs and selected investigations can help clinicians to reach a positive diagnosis, and modern pathophysiological research is showing an appreciation of the importance of both physical and psychological factors in FMD.

Introduction

Functional (psychogenic) movement disorders (FMD) are part of the spectrum of functional neurological disorders, some of the most prevalent disorders seen in neurological practice.1 In common with other functional disorders, there is an absence of appropriate health-service provision and research interest for FMD, despite their prevalence. These disorders occupy a grey area between neurology and psychiatry—often with neither specialist group willing to take charge—which has resulted in what has been described in relation to FMD as a “crisis for neurology”.2

There are three rationales behind this Review. First, there have been notable developments in diagnostic techniques, pathophysiological understanding, and treatments in FMD, which together represent a substantial advance in knowledge. Second, we wish to highlight an important shift that has taken place in approaches to functional disorders in general: the historically influential explanation for symptoms triggered by emotional trauma (and the research and treatment agendas that emerge from this explanation) has been challenged. Third, because of the enormous health-care and social-care costs associated with functional symptoms such as FMD, health professionals and medical scientists need to take an active interest in keeping up to date with best practice in diagnosis and management. FMD have traditionally been thought of as the most difficult of the functional neurological disorders to diagnose and manage, but we will show that they need not always carry such a reputation.

Section snippets

Terminology and definition

When experts cannot agree on a unified terminology for a disorder, there is likely to be a fundamental problem with understanding the underlying pathophysiology. This difficulty in understanding is certainly present for psychogenic disorders, including FMD, for which there are many descriptive terms to choose from (panel 1). The choice of term is not a trivial issue, because it directly affects case definition, diagnosis, treatment, research agenda, and explanations of illness that we give to

Epidemiology, quality of life, and cost

The subject of this Review represents an important issue because of its prevalence and effect on quality of life and health-care economics. FMD are part of the wide spectrum of functional or psychogenic neurological symptoms, which together account for 16% of new patients attending neurology outpatients' clinics.1 Accurate estimates of prevalence of FMD are hampered by case definition and the setting of the clinic from which cases are ascertained, and range between 2 and 20% of patients

Clinical features

Several historical features and examination findings are commonly noted in patients with FMD regardless of the movement disorder phenomenology. These features are not diagnostic of FMD, but can be helpful as part of the diagnostic process. Patients often describe the sudden onset of symptoms, which might be precipitated by a physical event (eg, injury or illness).9, 10 Symptoms can rapidly progress to become severe—a pattern that is unlike the slow progressive course of most movement disorders.9

Diagnostic criteria

We emphasised earlier that the diagnosis of FMD should as much as possible be a positive diagnosis. It should not be a diagnosis of exclusion, nor a diagnosis made on the basis of co-existence of a movement disorder with psychological disturbance. Co-existent psychological disturbance is common throughout organic neurological disease and is not an adequate symptom on its own to diagnose a psychogenic disorder.47

Operationalised diagnostic criteria for functional movement disorders include the

Pathophysiology

The earlier discussion of terminology shows a historical emphasis on psychological causation in FMD, as with other functional disorders. Psychiatric formulations based on late 19th and early 20th century concepts of conversion, somatisation, and dissociation still form the basis for psychiatric diagnoses in these disorders and, by extension, ideas regarding pathophysiology.52 However, patients with psychogenic disorders in general, including those with FMD, do not have the expected rates of

Management

There are limited studies available on which to base management decisions in FMD. It seems reasonable to presume that treatment of FMD can be informed by data regarding treatment of other functional neurological conditions, in particular those that involve motor symptoms.

In our view, the most important first steps in a successful treatment approach are effective communication of the diagnosis and the provision to patients and their families of a rational model within which to understand the

Prognosis

Long-term follow-up studies are confounded by the manner in which cases are diagnosed—typically by tertiary movement disorder clinics where patients with brief transient symptoms will be missed. In these studies, about half of patients report some improvement in symptoms at long-term (3–5 years) follow-up, although most patients remain out of work due to illness.71, 72 Good prognostic features include a short duration of illness, perception by the patient of effective management by the

Future work

This Review reports several areas in which evidence-based knowledge is limited. With specific reference to FMD, we wish to highlight the following areas and important questions.

Conclusions

We have described here how the correct diagnosis of FMD should rely on positive clinical characteristics and not on the presence of psychological trauma. The historical emphasis on psychological trauma as a triggering factor has perhaps skewed research agendas and neurological interest in these patients, and has certainly alienated many patients who cannot believe that their physical symptoms are related to psychological trauma. We do not aim to minimise the importance of psychological factors

Search strategy and selection criteria

For the purposes of this Review, we searched Medline between 1975 and December, 2011, for articles with the keywords “psychogenic”, “functional”, “conversion”, “movement disorder”, “parkinsonism”, “tremor”, “dystonia”, “myoclonus”, “chorea”, “tics”, and “gait”. We selected papers relevant to diagnosis, treatment, and pathophysiology.

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