Years published: 1990, 1999, 2003, 2018, 2023
NORD gratefully acknowledges Jon Stone MB, ChB, PhD, Consultant Neurologist, Professor of Neurology, University of Edinburgh, UK; Tim Nicholson, Honorary Consultant Neuropsychiatrist, South London & Maudsley NHS Foundation Trust and Kings College Hospital NHS Foundation Trust, London, Reader in Neuropsychiatry, Neuropsychiatry Research and Education Group, Institute of Psychiatry Psychology & Neuroscience, King’s College London; and Bridget Mildon, President/CEO FND Hope, Inc., for the preparation of this report.
Functional neurological disorder (FND) is a medical condition in which there is a problem with the functioning of the nervous system and how the brain and body sends and/or receives signals, rather than a structural disease process such as multiple sclerosis or stroke. FND can encompass a wide variety of neurological symptoms, such as limb weakness or seizures.
FND is a condition at the interface between the specialties of neurology and psychiatry. Conventional tests such as MRI brain scans and EEGs are usually normal in patients with FND. This had led, historically, to the condition being relatively neglected by both clinicians and researchers. However, it is now established that FND is a common cause of disability and distress, which may overlap with other problems such as chronic pain and fatigue. Encouraging studies support the potential reversibility of FND with specifically tailored treatments. New scientific findings are influencing how patients are diagnosed and treated, which is creating an overall change in attitude towards people with FND.
Older ideas that FND is “all psychological” and therefore always associated with stress or past trauma, and that the diagnosis is made only when someone has normal tests, have changed since the mid-2000s. The new understanding, including modern neuroscientific studies, has shown that FND is not a diagnosis of exclusion. It has specific clinical features of its own and is a disorder of the nervous system functioning in which many perspectives are necessary. These vary a lot from person to person. In some people, psychological factors are important; in others, they are not.
FND patients can experience a wide range and combination of symptoms that are physical, sensory and/or cognitive. The most common include:
• Functional limb weakness/paralysis
• Functional movement disorders including tremor, spasms (dystonia), jerky movements (myoclonus) and problems walking (gait disorder)
• Functional speech symptoms including whispering speech (dysphonia), slurred or stuttering speech
• Functional sensory disturbance includes altered sensation; e.g., numbness, tingling or pain in the face, torso or limbs; this often occurs on one side of the body
• Functional visual symptoms including loss of vision or double vision
Episodes of altered awareness
• Functional seizures (also called dissociative or non-epileptic) seizures, blackouts and faints: these symptoms can overlap and can look like epileptic seizures or faints (syncope)
Functional dizziness is often called persistent perceptual postural dizziness and has its own set of diagnostic criteria
Functional cognitive symptoms include difficulties with memory, concentration or word finding difficulty where there are typical features consistent with an FND diagnosis
Symptoms often fluctuate and may vary from day to day or be present all the time. Some patients with FND may experience substantial or even complete remission followed by sudden relapses of symptoms.
Other physical and psychological symptoms are commonly experienced by patients with FND although they are not defined as part of the disorder. These include chronic pain, fatigue, sleep problems, bowel and bladder symptoms, anxiety, panic attacks and depression.
The exact cause of FND is unknown, although ongoing research is starting to provide suggestions as to how and why it develops. Many different predisposing factors can make patients more susceptible to FND such as having another neurological condition, experiencing chronic pain, fatigue or stress. Childhood abuse, maltreatment or neglect and life stress, particularly around the time of symptom onset, is also more common in people with FND than in the general population. However, many people with FND have none of these risk factors which are also unfortunately common in all, including healthy, populations. As with most complex disorders affecting the brain, it’s likely that genetic factors play a role in the condition, but it is not a problem that someone should expect to pass on genetically.
At the time FND begins, studies have shown that there may be triggering factors like a physical injury, infectious illness, vaccination, panic attack or migraine which can give someone the first experience of neurological symptoms. These symptoms normally settle down on their own. However, in FND the symptoms become ‘stuck’ in a ‘pattern’ in the nervous system. That ‘pattern’ is reflected in altered brain functioning. The result is a genuine and disabling problem, which the patient cannot control. The aim of treatment is to ‘retrain the brain’, for example by unlearning abnormal and dysfunctional movement patterns that have developed and relearning normal movement. For seizures, the aim is to unlearn the seizure program that has become stuck in the brain, and which activates typically with very little trigger or perhaps just in response to being relaxed.
One way of thinking about FND is looking at it as a bit like a ‘software’ problem on a computer. The ‘hardware’ is not damaged but there is a problem with the ‘software’ and so the computer doesn’t work properly. A different analogy is a piano that is not broken but is out of tune. Conventional structural MRI brain scans are usually normal in FND unless the person has another neurological condition. Special functional brain scans (fMRI) used in research, which show patterns of brain activity, are starting to provide early evidence for how the brain goes wrong in FND. fMRI scans show changes in patients with FND which look different from healthy patients without these symptoms as well as being different from healthy people pretending to have these symptoms. Functional imaging is still just a research tool and is not developed enough to be used in diagnosing individual cases of FND. Scans support what patients and researchers already know – these are genuine disorders in which there is a change in brain functioning, which is out of the control of the person with FND.
Historically, FND has traditionally been viewed as an entirely psychological disorder in which repressed psychological stress or trauma gets converted into a physical symptom. This is where the term conversion disorder comes from. Psychological disorders and stressful life events, both recent and in childhood, are risk factors for developing the condition and can be relevant for some patients, but they rarely provide a full explanation for the cause of the condition and are absent in many patients. Patients do not have to be depressed, anxious or the survivor of adverse childhood experience to develop FND.
Modern theories propose that FND has many causes, which vary from patient to patient. One comparison is to think about heart disease. There are lots of causes of heart disease – smoking, genetic factors, diet and even stress-related/psychological factors such as depression. Smoking may be a factor in heart disease in many people, but it is not in everyone. The same analogy can be made for FND. In some, psychological factors such as past trauma or stress at the time of symptom onset in FND are important in understanding how the brain has gone wrong. In others, the presence of a problem like migraine or a physical injury may be the most important thing.
The exact prevalence of FND is unknown. However, research suggests FND is the second most common reason for a neurological outpatient visit after headache/migraine, accounting for one sixth of diagnoses. This means FND could be as common as multiple sclerosis or Parkinson’s disease.
FND can affect anyone, at any time, although it is uncommon in children under 10. FND is 2-3 times more likely to affect females than males for most symptoms, although when patients present over the age of 50, it occurs equally in both groups.
FND is not a diagnosis of exclusion. It should be diagnosed on the basis of positive physical signs and clinical features, and usually requires a neurologist or a doctor familiar with neurological diagnosis. There are dozens of these clinical features but some examples are:
Hoover’s test of functional leg weakness – the patient may have difficulty pushing their affected leg down (hip extension), but when they are asked to lift their unaffected leg, movement in the affected leg returns transiently to normal.
The tremor entrainment test for functional tremor – this is when the shaking of an arm or leg becomes momentarily better or alters frequency when the person concentrates on copying a movement that the examiner makes.
Functional seizures can often be recognized by a trained health professional using a combination of typical features such as: an episode of violent limb thrashing in which the eyes remain closed, side-to-side head movements, or an event lasting longer than 5 minutes where the eyes are closed, hyperventilation during a shaking attack or tearfulness on recovery.
Persistent postural perceptual dizziness (PPPD) which is recognized as a subtype of FND has its own diagnostic criteria set by the Barany society and adopted by the World Health Organization.
Functional cognitive disorder is characterized by the presence of variability in cognitive function, often called internal inconsistency. For example, someone with functional cognitive disorder may be able to recall in great detail an occasion when they forgot something, whereas someone with dementia often doesn’t think there is a problem.
These diagnostic positive signs should not be used in isolation. Instead, clinicians with expertise in neurological diagnosis need to assess features in combination, while being mindful of the possibility of comorbid other neurological or psychiatric disorders influencing the presentation.
FND can be hard to understand, and most people haven’t heard of it. Treatment should start with a clear and supportive explanation of the positive clinical features that have allowed the diagnosis to be made, even though scans and other laboratory tests may be normal.
When it goes well, understanding the diagnosis enables patients to see that they have a genuine and relatively common condition which has the potential for improvement over time. This creates a foundation for treatment to build upon. Written information, like that available at www.neurosymptoms.org or www.fndhope.org may help individuals comprehend this complex and difficult-to-understand disorder.
Evidence is now emerging for the efficacy of certain specific treatment developed for FND, especially physiotherapy for motor symptoms and psychological therapies for functional seizures. Other therapies such as speech therapy and occupational therapy may also have a role depending on the symptoms.
For patients with motor symptoms such as limb weakness, gait problems or movement disorder, physical therapy from a therapist who understands FND can be helpful. Physiotherapy approaches are active treatments that focus on retraining movement patterns that have gone wrong. There is some evidence from clinical trials that physiotherapy designed specifically for FND can be helpful for some patients. In recent years, we have learned that physical therapy for FND is different from that used for stroke or MS in many ways. For example, patients with stroke benefit from being asked to focus on the affected body part, whereas in FND that tends to make things worse. Physical therapy for FND promotes automatic movements and reduces the abnormal brain patterns that have been interfering with movement.
Psychological therapy such as cognitive behavioral therapy (CBT) is generally the first line of treatment for patients with dissociative (non-epileptic) seizures or attacks as part of their FND and is supported by clinical trials. It is also often used for other FND symptoms. CBT includes time to learn more about their attacks and recognizing brief warning symptoms and learning techniques to regain control. For some patients, it is helpful to look more widely at thoughts, emotions, and experiences that could have played a role in the development of symptoms. For those patients without anxiety and depression, psychological therapy may still be useful in regaining confidence. FND itself is often experienced as a stressful condition to manage and live with. Other types of psychological therapies can also be used depending on the individual patient, such as mindfulness, psychodynamic interpersonal therapy (PIT) or more trauma-focused approaches.
Occupational therapy assists patients in finding adaptations and regaining confidence in their ability to carry out daily activities in the home or workplace. Occupational therapy can help build on other therapies to contribute to a better overall quality of life.
For patients with speech symptoms as part of FND, speech therapy is an important part of treatment. As with physical therapy, the approach is different from that used, for example, after a stroke.
There is no research evidence that any specific medication is beneficial for FND itself, but medications may be useful for other symptoms commonly occurring with FND such as pain, migraine, other headaches, insomnia, PTSD, anxiety, panic attacks or depression. Other therapies such as eye movement desensitization reprocessing therapy (EMDR – effective for PTSD), virtual reality (VR) treatments, transcranial magnetic stimulation (TMS) and other new treatments are being investigated in research studies.
Not everyone with FND can benefit from treatment even if they do understand their condition and are well motivated.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Some current clinical trials also are posted on the following page on the NORD website:
For information about clinical trials sponsored by private sources, contact:
For information about clinical trials conducted in Europe, contact:
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Neurosymptoms FND Guide
Free website with self-help information about all aspects of FND.
Written by Prof. Jon Stone, Neurologist, Edinburgh, UK http://www.neurosymptoms.org/
Accessed May 30, 2023
MyFND/ A free app designed to provide information and self-help for symptoms of FND.
https://myfnd.co.uk/. Accessed May 30, 2023.
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