Functional Neurological Disorder – what it is, why it occurs and what should be done?

Posted by Richard Maddicks

15th July 2025

Definition(s)

The diagnostic criteria for Functional Neurological Disorder, as stated in the Diagnostic Statistical Manual (DSM-5), are as follows:

1. i) “One or more symptoms of altered voluntary motor or sensory function;
2. ii) clinical findings provide evidence of incompatibility between the symptoms and recognised neurological or medical conditions;

iii) the symptom or deficit is not better explained by another medical or mental disorder;

iv) the symptom or deficit causes clinically significant distress or impairment in social, occupational, or other important areas of functioning or warrants medical evaluation” (Diagnostic and Statistical Manual of Mental Disorders, 2013). Put simply, someone is experiencing real, debilitating, physical symptoms that have no neurological or medical explanation and are caused by communication problems between the brain and the body. The nervous system hasn’t been damaged or attacked by disease, it just isn’t functioning properly.

Photo by Fotos on Unsplash

There are a variety of sub-types of FND that people may experience; with weakness or paralysis, with abnormal movement, with swallowing symptoms, with speech symptoms, with attacks or seizures, with anaesthesia or sensory loss, with special sensory symptom, or with mixed symptoms. These symptoms will either be present for less than six months (acute) or for more than six months (chronic), and may or may not have a psychological stressor attached (Diagnostic and Statistical Manual of Mental Disorders, 2013). If you would like to find out about symptoms in more depth, you can click here https://www.neurosymptoms.org/symptoms/4594357993

Aetiology

So, what can cause the functioning of the nervous system to go wrong? As described on “Functional Neurological Disorder (FND): a patient’s guide” written by Professor Jon Stone, Consultant Neurologist, there are three sources of symptom development. Factors may occur prior to the onset of symptoms, which may take the form of early childhood trauma, previous adverse experiences or genetic factors. The cause may be during the onset of the symptoms i.e. a person may be suffering with depression, or going through a stressful job loss. Factors may also have an effect after symptom development, for example, the stigma and worry of the diagnosis, or stress about the cause and consequence (Stone, 2021). However, there are a significant proportion of people that are given the FND diagnosis but have not experienced any distressing life events, so the aetiology is hard to pin down, suggesting there may be more of a pre-disposing biological aspect. Studies have also identified a mismatch between someone’s subjective response to stress compared to their biological stress response, suggesting those with FND have impaired interoception (perception of your internal bodily sensations). Researchers suggest taking a biopsychosocial approach could be crucial in developing further knowledge of FND’s aetiology (Keynejad et al., 2018).

Treatment

FND is a condition that sits between neurology and psychiatry, so who treats it and how is it treated? Up until fairly recently and still to this day, the disorder continues to be misunderstood by many health care professionals who have very little knowledge of the disorder and how to treat it. As it is a diagnosis of exclusion, it can only be made after other possible conditions have been ruled out, often meaning the person remains undiagnosed for a significant period of time. This can be a significant source of someone’s distress and anxiety, as it fuels symptom severity and the debilitating aspects of FND. This can also contribute to a poorer outcome, as the longer the disorder goes untreated the harder it can become to treat.

In order to help with the specific symptoms, there are a wide range of treatments that may provide some benefit. Each person is completely different, and how they cope and improve will very much vary. Some examples of therapy are physiotherapy, occupational therapy and speech therapy. These forms of treatment, especially physiotherapy, have been found to be very beneficial, as a tailored approach can help the patient re-learn natural movements, increasing and strengthening the brains’ neural pathways and help to repair damaged parts (“Physio/Physical Therapy.” FND Hope International, 2020).

Psychological therapies also frequently form part of the treatment approach. For some, the issue may lie in how they process emotions. A study by Aybek et al., (2015) found increased activation in certain parts of the brain in those with FND, when compared to healthy controls. Parts of the brain affected were the amygdala, periaqueductal grey matter, cingulate gyrus and supplementary motor area, all of which are involved in the processing of fearful stimuli and negative emotions, suggesting abnormal emotional processing. Psychological therapies can therefore be beneficial for some in helping to change the way emotions and thoughts are processed, one example being CBT. CBT involves targeting and addressing unhealthy thoughts and emotions, ensuring they are processed correctly. There has been much research into the benefits of CBT; one recent study found those with FND showed significant improvement after receiving CBT in a neuropsychiatric outpatient clinic (O’Connell et al., 2019).

Psychodynamic therapy is another therapy that can be used in situations where someone has experienced previous trauma; the trauma may not have been properly dealt with or processed and therefore supressed for a long period of time. The trauma can then present itself as a physical symptom years later (“Psychological Treatment”. FND Hope International, 2020). This link to previous trauma is concisely explained in Suzanne O’Sullivan’s book ‘It’s All in Your Head’; “Against all logic, people’s subconscious selves choose to be crippled by convulsions or wheel-chair bound rather than experience the anguish that exists inside of them” (O’Sullivan, 2016).

An integrated interdisciplinary approach is needed when it comes treating FND, one that combines numerous perspectives; neurological, psychiatric and psychological. There is a critical need to educate clinicians further, across a range of medical professions; with a focus specifically on how best to deliver an FND diagnosis to ensure maximum engagement and cooperation (Williams & Utsav Aiya, 2020).

 Diagnostic Difficulties

There are psychological issues surrounding the impact of many medical diagnoses, however, processing an FND diagnosis may be harder; the individual has been given a diagnosis of a psychological disorder, having been so convinced that it had medical origin. This ‘dissonance’ is often extremely difficult to reconcile as symptoms experienced can be so physically disabling and intrusive. They may feel deflated with such a diagnosis, frustrated and refuse to accept it, generating additional stress and worsening their symptoms. This worry and anxiety could then spread to what they think their family, friends or work colleagues might consider this diagnosis to mean. The problem is worsened due to the lack of attention FND gets in the media and public domain and an associated lack of understanding.

When making the diagnosis of FND, there are a number of alternative diagnoses that can be given instead and medical professionals have to be very careful when diagnosing someone. A person could be suspected of consciously fabricating symptoms or malingering i.e. those who exploit the nature of the disorder and fake symptoms, for some personal or practical gain. Reasons may be for financial compensation or avoidance of criminal charge. An alternative diagnosis of factitious disorder may be given for someone feigning symptoms due to their psychological background (Mellers, 2005). This may be because of a personality disorder, depression or childhood trauma. They lack insight into their medical condition and fail to see its severity(“Factitious disorder – Symptoms and causes” Mayo Clinic, 2021). The implication of malingering and factitious disorders could be the negative representation of those diagnosed with FND, undermining the validity of their disabling symptoms and experiences.

Breaking down the barriers

Is it possible that part of our struggle managing these conditions reflects our cultural heritage of artificially separating the psychological and the somatic (biological)? This potentially undermines efforts to investigate and understand psycho-somatic illness and associated disability.  It can also create clinical silos and chasms between health care professionals, detracting from inter-disciplinary working and joined up treatment approaches. The lack of opportunities for health care professionals to engage in training and skills development in relation to these conditions could prove to be self-perpetuating, contributing to reduced confidence and competencies in working with these patients.

I hope this gives the reader some insight into what I think is a fascinating disorder and one that still has so many unknowns. Here are some great resources and websites which I have found and may be of interest.

https://rarediseases.org/rare-diseases/fnd/ National Organisation for Rare Disorder

https://www.neurosymptoms.org Functional Neurological Disorder (FND): a patient’s guide

https://fndhope.org FND Hope

https://www.fndaction.org.uk FND Action

Author: Olivia Fretwell

office@psychologychartered.co.uk

 Let us know your thoughts and opinions on functional neurological disorder and if anyone has any real-life case studies of dealing with patients with FND, we would love to hear your experiences! Please feel free to contact us on any of our social media.

 Resources

 American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders(5th ed., pp. 318, 319). Washington.

1. Aybek, S., Nicholson, T., O’Daly, O., Zelaya, F., Kanaan, R., & David, A. (2015). Emotion-Motion Interactions in Conversion Disorder: An fMRI Study. PLOS ONE, 10(4), e0123273. doi: 10.1371/journal.pone.0123273
2. Factitious disorder – Symptoms and causes. (2021). Retrieved 15 January 2021, from https://www.mayoclinic.org/diseases-conditions/factitious-disorder/symptoms-causes/syc-20356028
3. Hoeft, F., Gabrieli, J., Whitfield-Gabrieli, S., Haas, B., Bammer, R., Menon, V., & Spiegel, D. (2012). Functional Brain Basis of Hypnotizability. Archives Of General Psychiatry, 69(10), 1064. doi: 10.1001/archgenpsychiatry.2011.2190
4. Keynejad, R., Frodl, T., Kanaan, R., Pariante, C., Reuber, M., & Nicholson, T. (2018). Stress and Functional Neurological Disorders: Mechanistic Insights. Journal Of Neurology, Neurosurgery And Psychiatry, 1,2,9. doi: 10.1136/jnnp-2018-318297
5. Mellers, J. (2005). The approach to patients with ‘‘non-epileptic seizures’’. Postgraduate Medical Journal, Volume 81(Issue 958), 498. doi: http://dx.doi.org/10.1136/pgmj.2004.029785
6. Milán-Tomás, Á, Persyko, M., Del Campo, M., Shapiro, C., & Farcnik, K. (2018). An Overview of Psychogenic Non-Epileptic Seizures: Etiology, Diagnosis and Management.Canadian Journal of Neurological Sciences / Journal Canadien Des Sciences Neurologiques,45(2), 130-136. doi:10.1017/cjn.2017.283
7. O’Sullivan, S. (2016). It’s All in Your Head(1st ed., p. 15, 42). Vintage.
8. O’Connell, N., Watson, G., Grey, C., Pastena, R., McKeown, K., & David, A. (2019). Outpatient CBT for Motor Functional Neurological Disorder and Other Neuropsychiatric Conditions: A Retrospective Case Comparison. The Journal Of Neuropsychiatry And Clinical Neurosciences, 32(1), 58-66. doi: 10.1176/appi.neuropsych.19030067
9. Physio/Physical Therapy – FND Hope International. (2020). Retrieved 12 January 2021, from https://fndhope.org/fnd-guide/treatment/physiophysical-therapy/
10. Psychological Treatment – FND Hope International. (2020). Retrieved 12 January 2021, from https://fndhope.org/fnd-guide/treatment/psychological/
11. Stone, J. (2021). Symptoms – neurosymptoms.org. Retrieved 12 January 2021, from https://www.neurosymptoms.org/symptoms/4594357993
12. Williams, B., & Utsav Aiya, M. (2020). Special Journal Issue on Functional Neurological Disorder Brings Attention to a Neglected Field: Investigator Q&A – Psychiatry Advisor. Retrieved 13 January 2021, from https://www.psychiatryadvisor.com/home/topics/general-psychiatry/special-journal-issue-on-functional-neurological-disorder-brings-attention-to-a-neglected-field-investigator-qa/