Functional neurological disorders

Research and treatment should involve understanding why and not just how they develop

The group of clinical conditions that are now described as Functional Neurological Disorder (FND) used to be known by more uncomfortable names – hysteria, conversion disorder, or the hybrid hysterical-conversion. The change of terminology is welcome, although perhaps not its usage in the singular; after all the category brings together some quite disparate conditions.

With this change in terminology comes a change in the academic and clinical discourse. For the last century or so, the majority view has been that these functional disorders have psychological causes:  how they develop comes about through a process of loosening and disconnection between usually connected functions that need to be co-ordinated for effective motor or sensory function – dissociation; why they develop is explained as a response to some sort of psychological conflict that cannot be satisfactorily resolved – the emergence of disorder representing either symptomatic breakdown or a defensive manoeuvre to contain the conflict.

A shift in emphasis

The current FND discourse is relatively uninvolved with ideas about why FND occurs. Its focus is on antecedents that seem relatively trivial psychologically and upon mechanisms of symptom production – the how. Modern approaches in neuroscience allow studies of the physiology of symptom production that give new meaning to older ideas like dissociation and somatosensory amplification and more recent ideas about interoception, helping to explain some of the specifics of presentation – how some symptom states are generated – or to suggest why some individuals are especially susceptible.  Such research may yield interesting insights into the nature of these conditions and perhaps offers the future possibility of new therapeutic approaches.

A corollary has been a tendency to downplay the role of interpersonal factors in aetiology or maintenance: early or later life experience is hardly discussed as having a potentially meaningful relationship to onset or persistence of FND. Enthusiasts for a quasi-neurological cause for FND are keen to quote a systematic literature review¹ which found that many people do not report severe life events as antecedents to onset. Three of the most widely used patient-facing resources² lead on “problems with functioning of the nervous system” in their definitions of FND, while not offering the possibility that an important cause might be psychological. Psychological intervention, if any is offered, is focussed on overcoming barriers to social and physical rehabilitation and formal psychological therapy may not even mentioned as an option^3-4.

There are apparent clinical benefits to this approach, which no doubt account for its current popularity. Most significantly it can facilitate engagement during consultations and thereby rehabilitation efforts, especially in those cases where a less medical-sounding diagnosis is “not well accepted by patients who feel that (it) implies that their symptoms are inauthentic…”⁵

Where does psychotherapy fit in now?

Against this background a recent systematic literature review⁶ has summarised evidence for the effectiveness of psychological therapies in FND – 12 studies of CBT and seven of psychodynamic therapy. Therapy trials ought to be a test of some of the ideas about causes of FND and its associated disability, because CBT sits mainly as an adjunct to rehabilitation whereas psychodynamic therapy is aimed at the interpersonal distress that, putatively, has a causal as well as maintaining role.

The results are, frustratingly but not surprisingly, inconclusive. Most of the studies are small and had methodological weaknesses that prevent us getting a definitive answer. The lumping together of participants with quite different clinical presentations makes it impossible to answer the question “what might work for whom?”. We don’t know what proportion of eligible patients will accept either therapy when it is offered in an encouraging and supportive way.

Even so, two results stand out from this useful and well-conducted review. The first is that psychotherapy, including psychodynamically-informed therapy, can be acceptable to people with a range of functional disorders. The second is that the CODES trial⁷ – by far the largest and best conducted in the field – produced a number of non-specific benefits in mood, wellbeing, quality of life and so on, but had no effect on the frequency or severity of the primary presenting problem which was non-epileptic (functional) seizures.

Where next?

The discourse on FND needs to be rebalanced. A full formulation should include an understanding of psychological and social factors in the generation and maintenance of functional states – not just as coincidental co-morbidities or as natural consequences of disability but as meaningfully related to the disorder. Current evidence on life adversity is not robust enough to dismiss this possibility:  severe threatening events are not what one would typically expect to find as the explanatory exposure in this context⁸, and life events interviewing is a blunt tool for exploring more nuanced interpersonal conflicts.

The framing of FND as primarily a problem of nervous system function may get in the way of this broader formulation, making it harder for people to discuss and understand the psychosocial aspects of their illness.

Caricaturing of psychological perspectives doesn’t help.  If clinicians really say to their patients  “It’s all in your head”⁹  or describe them (presumably to colleagues) as work-shy hysterics¹⁰ then what’s needed is some re-education of those clinicians rather than reformulating functional disorders so that patients learn to say “I have a real dysfunction of networks in my brain”⁹.  We must be careful not to collude with the stigmatising of mental health problems by a reluctance to acknowledge that they too are respectable states with which to be diagnosed.  When I first started in medicine, patients were frequently not told they had cancer – as a way of avoiding distressing and uncomfortable consultations. Nobody accepts that now, but it feels as if that’s where we are with FND.

It is a mistake to believe that everybody wants a disease-like diagnostic label and not everybody is offended by sensitively handled discussion of psychological causes of physical illness. For example Markus Reuber and colleagues in Sheffield have shown, as does the latest literature review, that if care is taken with early introduction of the ideas then psychological therapy, even when informed by psychodynamic principles, can be delivered in brief and acceptable formats to people with functional symptoms. Of course not everybody will accept a psychological approach, but an early over-emphasis on mechanistic explanations and short-term goals in therapy just makes it more difficult to address important psychological and social issues at a later stage, if all is not going well.

Writing a little while ago, Anthony David¹¹ talked about a happy “we’re-all-friends-together-let’s get-rid of Cartesian-dualism” camaraderie that pervades this field. He was talking about something a bit different, but it’s still true that “an end to dualism” won’t do to explain where we are now. Apart from the misunderstanding of dualism that the slogan implies, it’s wrong because what we need is more openness about discussing with patients the possible primarily psychological causes and treatments that are relevant in FND even if that may bring uncomfortable consultations – a part of the continuing confrontation of stigmatisation in psychological illness. These ideas need to be tested in careful clinical trials that allow for testing of the value of psychological formulation and intervention as a substantial rather than adjunctive part of treatment, and involve evaluation of mediators and moderators of outcomes that can help unpack the complex nature of this group of disorders. We should do no less – we are still a long way from understanding functional disorders and treating them effectively, and the prognosis for FND is certainly not good as things stand¹².

1. Ludwig L, Pasman JA, Nicholson T, Aybek S, David AS, Tuck S, Kanaan RA, Roelofs K, Carson A, Stone J. Stressful life events and maltreatment in conversion (functional neurological) disorder: systematic review and meta-analysis of case-control studies. The Lancet Psychiatry. 2018 Apr 1;5(4):307-20.
2. FND Action https://www.fndaction.org.uk/what-is-fnd-2/; FND Hope;  https://www.fndhope.org/   Neurosymptoms https://www.neurosymptoms.org/
3. Johns R. I feel I am missing a piece of the puzzle. BMJ. 2020 Apr 8;369.
4. Wong M. Telling me you don’t know is ok. BMJ. 2020 Jan 8;368.
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7. Goldstein LH, Robinson EJ, Mellers JD, Stone J, Carson A, Reuber M, Medford N, McCrone P, Murray J, Richardson MP, Pilecka I. Cognitive behavioural therapy for adults with dissociative seizures (CODES): a pragmatic, multicentre, randomised controlled trial. The Lancet Psychiatry. 2020 Jun 1;7(6):491-505.
8. Kanaan RA, Craig TK. Conversion disorder and the trouble with trauma. Psychological Medicine. 2019 Jul;49(10):1585-8.
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11. David AS. Functional disorders, Cartesian dualism and stigma: where does the dualism really lie? Journal of Neurology, Neurosurgery & Psychiatry 2012;83:869.
12. Edwards MJ. Functional neurological disorder: an ethical turning point for neuroscience. Brain 2019 Jun 26;142(7):1855-7.