Introduction

Functional neurologic symptoms are often seen in neurology outpatients, in more than 16% of referrals (1). The history of people with functional symptoms dates back to Hippocrates, who named them 'hysterical`. In the seventeenth century Charles Lepois (Carolus Pinto, 1563-1633), Thomas Willis (1621–1675) and Thomas Sydenham (1624-1689) studied the disease and had already astonishing insights in phenomenology and possible causes of the symptoms. In the nineteenth century especially Pierre Briquet (1796-1881), Jean-Martin Charcot (1825-1893) and Georges Gilles de la Tourette (1857-1904) dealt with functional neurologic symptoms and of course Sigmund Freud (1856- 1939) and Pierre Janet (1859-1947) who suggested psychogenic causes for the disease and established the paradigm of conversion- dissociative disorder, which continues to influence concepts of functional disorders today.

The psychogenic concept is still the subject of scholarly debate. Epidemiological studies in recent years led to a reduction in promoting traumatic events as the unique cause for developing functional neurologic symptoms (1,2,3,4). Beyond doubt in many patients there are psychological factors detected or a mental trigger provoking functional neurologic symptoms, but not always. The psychiatric comorbidity is high, rates of depression and anxiety, however, are not higher than in other neurological diseases (19% - 57%, 38% - 52% respectively) and in 21 - 56% of persons with functional symptoms no psychopathological symptoms are detectable (5). Criteria for conversion disorder (functional neurological symptom disorder) are modified in DSM V to emphasize the essential importance of the neurological examination, and in recognition that relevant psychological factors may not be demonstrable at the time of diagnosis.

Most persons affected have no neurologic disease, but about 12% of neurologic patients develop functional symptoms in addition to their medically explained illness, and about 7% of persons with multiple sclerosis (pwMS) suffer from functional symptoms (6).

Although diagnostic criteria for multiple sclerosis (MS) have become more sensitive with magnetic resonance imaging (MRI), the attribution of individual relapses may not always be correlated to a particular lesion seen on imaging. It is therefore possible to consider functional symptoms as being true relapses. This may have an impact on drug therapy or other consequences.

Case report - 21 year old woman

The young woman was diagnosed with definite MS at the age of 17. Due to her early illness and a difficult situation at home, she suffered for three years from major depressive episodes and was therefore treated. During the rehabilitation period in our clinic she was partly in remission concerning the depression.

When she entered our clinic, she had had a relapse three weeks before and was wheelchair-bound. During her rehabilitation course with intensive physiotherapy and occupational therapy, she improved quite well and after three weeks she was able to walk, slowly but securely without a walking aid.

After a Sunday at home, she suddenly could not walk any more, hardly with a walking frame or stick and had to use a wheelchair again. She showed a very unusual gait pattern, not spastic nor atacticataxic, but buckling severely with the supporting leg on both sides, without being at risk of falling. When sitting, she suffered from a heavy tremor of the right leg. We did not perform an MRI nor administer steroids, assuming a functional cause of the 'relapse`, but continued intensive physiotherapy.

Talking to her she admitted that her boyfriend had abandoned her at the weekend and that she was very upset. Also she was afraid of having a relapse of MS.

She felt relief from the explanation that a mental burden might induce a temporary worsening of function without a proven organic cause, i.e. without enhancement of an inflammatory process and she was motivated to continue physical exercise. Within three days her gait pattern normalized and she was able to walk again without aid.

Aetiology

There are different causes, biological and psychological, which can lead to functional neurologic symptoms. In the history above both were present.

Psychodynamic factors can cause functional physical symptoms subconsciously attempting to resolve unperceived conflicts or meeting emotional needs (eg social interaction, sympathy). Anxiety, depression and personality disorders also may play an important role in promoting them (7). Yet to attribute all functional syndromes as purely 'psychogenic` would be too narrow. In a review Kranick found many patients (21-56%) with functional disorders not having psychiatric comorbidity and not having suffered from childhood trauma (5). 64 Patients affected reported slightly higher rates of childhood trauma, specifically greater emotional abuse and physical neglect, but not more childhood physical or sexual abuse (3). Also neurobiological factors such as organic disease, physical trauma or long bed-rest may trigger functional symptoms.

The bio-psycho-social model is certainly of great value in understanding the pathogenesis of functional syndromes, even more than in other mental or organic disorders (3,4,5).

According to recent studies a new model emerged, which conceives functional motor symptoms as an involuntary but learnt habitual movement pattern driven by abnormal self-directed attention. Abnormal expectation, prediction and perception of movement on different levels of the central nervous system provoke a deficient sense of agency and performance of movement (9,10,14). Mental stress (life events, emotional disturbance, anxiety and others) as well as physical events (injury, illness) may act as a trigger.

It must be emphasised, that functional symptoms are not to be confounded with malingering. There are sensitive methods to detect physiological changes related to functional neurologic symptoms, which are different from the activation pattern associated with simulated weakness (7,8,9).

The diagnosis is preferably made by positive features and not only by exclusion of organic causes (11). The terms 'non-organic` or 'medically unexplained symptoms` should therefore be avoided. In the case history mentioned above, the gate pattern was not explainable with any neurologic pathophysiology (i.e. paresis, ataxia, spasticity). The patient also suffered from mental stress. The course and follow-up as well confirmed the diagnosis of a functional motor symptom.

Treatment

Controlled studies of treatment of functional symptoms are rare. As the bio-psycho-social model of pathophysiology has the greatest impact, multidisciplinary therapies in a rehabilitation program are most promising.

Patients with motor symptoms respond well to physiotherapy (12), proper movement can be re-learned that way and the patient feels respected and well understood treating his symptoms by exercise, he is convinced of being quite organic. Physiotherapists with specific experience and empathy are needed. A very new and important consensus recommendation highlights a symptom model and therapeutic approach to functional motor disorders (14).

Key elements of successful treatment (11,12,13,14):

• communicating the diagnosis of functional symptoms, apart from MS, emphasizing the reversibility of symptoms
• patient education about mind-body interplay, using common examples such as worsening of tremor with anxiety or impaired speech when talking before an audience
• explore triggering factors and treat them if possible (illness, anxiety, pain)
• physiotherapy and occupational therapy by therapists with experience
• hospitalization in a specialized rehabilitation clinic, if the patient is severely disabled or lives in a situation that supports disability
• attention to the presence of comorbid medical and psychiatric conditions that may have been overlooked or neglected when the diagnosis of functional disorder was made, or which develop during the course of treatment
• psychotherapy, especially cognitive-behavioural therapy, if psychiatric co-morbidity is assumed or if the patient needs special support or guidance about coping strategies

References

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2. Edwards MJ, KP Pathia KP, Functional (psychogenic) movement disorders: merging mind and brain. The Lancet Neurology 2012; Vol11, 250-260

3. Kranick S, Ekanayake V, Martinez V, et al, Psychopathology and psychogenic movement disorders. Mov Disord. 2011;26(10):1844-50

4. Stone J, Edwards MJ, How ‘‘Psychogenic’’ Are Psychogenic Movement Disorders? Mov Disord. 2011;26(10):1787-1788

5. Kranick SM et al, Psychogenic Movement Disorders and Motor Conversion: A Roadmap for Collaboration between Neurology and Psychiatry. Psychosomatics 2011;52:109–116

6. Stone J, Carson A, Duncan R, et al, Which neurological diseases are most likely to be associated with symptoms unexplained by organic disease. J Neurol 2012;259(1):33-38

7. Van der Kruijs SJM, Bodde NMG, Carrette E, et al, Neurophysiological correlates of dissociative symptoms.J Neurol Neurosurg Psychiatry 2014;85(2): 174-179

8. Stone J, Zeman A, Simonotto E, et al, fMRI in Patients With Motor Conversion Symptoms and Controls with Simulated Weakness. Psychosomatic Medicine 2007;69:961-969

9. Voon V, Gallea C, Hattori N, et al, The involuntary nature of conversion disorder. Neurology 2010;74:223-228

10. Edwards MJ, Adams RA, Brown H, et al, A Bayesian account of 'hysteria`. Brain 2012;135: 3495-3512

11. Edwards M, Functional neurological symptoms an MS. www.mstrust.org.uk

12. Nielsen G, Stone J, Edwards MJ, Physiotherapy for functional (psychogenic) motor symtpoms: a systematic review. J Psychosom Res 2013;75(2): 93-102

13. Rosebush PI, Mazurek MF, Treatment of conversion disorder in the 21st century: have we moved beyond the couch? Curr Treat Potions Neurol. 2011;13(3):255-66

14. Nielsen G, Stone J, Matthews A, Physiotherapy for functional motor disorders: a consensus recommendation. J Neurol Neurosurg Psychiatry 2014 Nov 28. pii: jnnp-2014-309255 Epub