What is FND?


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What is FND?

Functional Neurological Disorder (FND) is an altered motor or sensory function, not recognised in organic neurological conditions. Also known as Functional Neurological Symptoms Disorder (FNS), Functional Movement Disorder (FMD), Non-epileptic Attack Disorder (NEAD), Dissociation or Non-Organic. Previously it has been called psychogenic, psychosomatic, somatogenic, hysteria and Conversion Disorder but these labels refer to the time when it was assumed that FND was purely a mental health disorder.

Your symptoms are real

It is essential to remember that your symptoms are REAL, the symptoms are not made up, you have no control of these symptoms and no one should make you feel that you are imagining things.  The way in which the diagnosis fits in with Neuropsychiatry (mental health) is that the triggers or stressors may have come from past or present emotional trauma. It may also have come about as a result of an illness, physical trauma, an operation or many other reasons though. People who don’t have a good understanding of FND tend to jump on the mental health bandwagon and this lack of understanding can cause a lot of emotional trauma in itself as people feel they must be going mad or that people don’t believe them.

FND explained

FND is a disorder of the nervous system, where signals to and from the brain are not sent or received properly.  This causes the body part or system that the signals are feeding, to not function as it should.  For instance, (this is just an analogy to try to explain what is happening) if the signals don’t have enough energy to reach their destination, this could result in symptoms such as paralysis.  If they do reach their destination but have too much energy they may result in an overactive reaction such as tremors, jerky movements etc. It is not something that you have any control over.  This nervous system malfunction causes symptoms that mimic other conditions such as MS, Epilepsy, Parkinson’s and Stroke but when further tests are carried out, none of the abnormalities that are found in these conditions are present.

There is a lot of work to be done to describe exactly what is going on at the molecular level in the brains of those suffering from FND. Some research carried out in the USA, using 3D Functional MRI, has shown that there are actually some changes in the brain of FND sufferers.

What are the symptoms?

The symptoms depend on which body part is being affected but the following are typical of FND, paralysis, weakness, unsteady gait, stroke-like symptoms, tremors, dystonia, bladder and bowel problems, speech and communication problems, swallowing, transient vision changes, brain fog, trembling felt inside, dizziness and nausea, chronic pain, fatigue, blackouts, dissociation and seizures (NEAD- Non-Epileptic Attack Disorder).  Someone may only have one symptom or whilst others may have many.  For a complete list of symptoms, please visit the Neurological Symptoms website written by Professor Jon Stone.

Diagnosis & causes


The first thing you would do on the onset of symptoms, depending on what they are, is to either visit your GP or A&E department. If you are in A&E, you may be admitted or see a neurologist within the department. If a GP or the doctor you see in A&E is familiar and competent in spotting and diagnosing Functional Symptoms, they may tell you their suspicions there and then. There are some positive tests that can be done by the doctor during their neuro/ physical examination but you wouldn’t be aware of their importance. This means that doctor may know that it is functional. You will more than likely be sent an OPD appointment to see a Neurologist in clinic. Due to the curriculum when training to become a Neurologist, the doctors are unbelievably not usually taught about FND until they reach Registrar level. If possible it is worth getting a referral to the local FND friendly Neurologist if FND is suspected. The Neurologist may be certain that your symptoms are Functional but may wish to rule out any other underlying problems which may be running alongside your FND. These may be Blood Tests, Nerve Conductive Tests, an EEG or an MRI for instance. We have been informed by specialists in the field that FND is NOT a Medically Unexplained Symptom.

What causes FND?

Unfortunately, little is understood about the causes of FND and the triggers for the onset of symptoms vary considerably from physical injury, infectious illness, a stressful event or migraine.

According to NORD, “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. However, some people with FND have none of these risk factors.”

How many people have FND in the UK?

FND is listed as a rare disease however, of people attending a neurology outpatients appointment for the first time, functional symptoms are the most common reason, after only headache/migraine. It is difficult to put a number on but it is known to be more common than MS, Epilepsy, Parkinson’s disease and other conditions it mimics.  Many people don’t realise they have FND as it is often confused with other issues. Sometimes the doctor may say something like “you have functional digestive problems”,  “you have dissociative episodes”, “you have conversion disorder” “you have a neurogenic bladder (without having another organic problem”, or “your symptoms are functional”.

Further reading

Professor Jon Stone MBChB FRCP PhD, Consultant Neurologist (NHS Lothian) has a fantastic resource describing symptoms, causes, treatments and useful links here.

The NHS North Bristol NHS Trust describes functional neurological symptoms as “neurological symptoms that are genuine, but not due to a disease of the nervous system.” Read more here.

Sheffield NHS teaching hospital finds that FNDs are quite common, occurring in about one-quarter of the patients they see in their neurology clinics. Read more.

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