Functional neurological disorder
Functional neurological disorder (FND) describes a problem with how the brain receives and sends information to the rest of the body.
It's often helpful to think of your brain as a computer. In someone who has FND, there's no damage to the hardware, or structure, of the brain. It's the software, or program running on the computer, that isn't working properly.
The problems in FND are going on in a level of the brain that you cannot control. It includes symptoms like arm and leg weakness and seizures. Other symptoms like fatigue or pain are not directly caused by FND, but are often found alongside it.
Symptoms of FND
FND can have many symptoms that can vary from person to person. Some people may have few symptoms, and some people may have many.
A diagnosis of FND should be made because you have one or more clinical features that a specialist can recognise as typical of FND. It shouldn't be made just because scans or tests for other neurological conditions that have similar symptoms are normal.
What is a clinical feature?
A clinical feature is a distinctive way that your symptom presents that is unique to FND. For example, it could be that your eyes close during seizures, or that limb weakness briefly disappears during certain physical tests. Clinical features are what specialists use to identify FND from other neurological conditions with similar symptoms.
Functional limb weakness
Functional limb weakness is when a leg or an arm doesn't work properly. In FND, this happens because of a problem with how the nervous system is functioning.
It can cause a range of symptoms, including:
- problems walking
- heaviness down one side
- dropping things
- feeling like a limb isn't part of you
Functional limb weakness can often look a symptoms of a stroke or multiple sclerosis.If you have FND, any scans you have will show no damage to the brain to explain the weakness.
A specialist will diagnose functional limb weakness based on specific clinical features (symptoms) they find when they examine you.
A functional seizure (also called a dissociative seizure) is an episode where someone loses either awareness of, or their ability to interact with, their surroundings. It may look like an epileptic seizure or a faint.
A functional seizure can appear as:
- uncontrolled shaking
- suddenly going motionless and unresponsive
- staring without responding to surroundings
Some people are aware that seizures are about to happen, while others experience them without warning.
A specialist will ask you and your friends or family about what happens during a seizure, and will look at any video footage you can provide, to decide if it's epilepsy, a faint or a functional seizure.
Tremor is uncontrollable shaking of part of the body. It's most often found in the arms and legs.
Functional tremor can come and go throughout the day, and change in speed and strength.
A specialist will diagnose functional tremor based on specific features of your symptoms that they find when they examine you.
Functional dystonia is a type of muscle spasm. It causes a part of the body to become stuck in an unusual position. This can be for a short or a long period of time.
Someone with functional dystonia will often present with curled fingers, a clenched hand, or an ankle that turns in.
Functional gait disorder
Functional gait disorder describes the problems walking that you may experience as part of FND.
You may find you have a dragging leg, that you feel unsteady when walking, or that you make excessive movements when walking.
A specialist will diagnose functional gait disorder based on clinical features, like the way your walking changes when doing different activities.
Functional facial spasm
Functional facial spasm is when there are muscle spasms in the face. These can lead to problems like a narrowing of the eye or the pulling of the mouth or jaw upwards, downwards or to the side.
A tic is a fast repetitive movement or sound that happens suddenly. Functional tics can be a symptom of FND.
Functional tics can look similar to the tics in Tourette's syndrome. A specialist will look at the clinical features of your tics to make a diagnosis. It's quite common to have both functional tics and Tourette's syndrome.
Functional jerks and twitches
A symptom of FND can be jerks or twitches, which is when someone makes sudden movements.
Everyone experiences random jerks occasionally, like when you jolt awake as you're falling asleep. In FND, however, these uncontrolled jerks and twitches can become much more frequent.
Functional drop attacks
Functional drop attacks are when someone falls to the ground suddenly, without losing consciousness.
Functional sensory symptoms
A symptom of FND can be numbness, pins and needles, or a feeling that a limb isn't part of your body.
Functional cognitive symptoms
Problems with your memory or concentration can be a symptom of FND.
You might find that you:
- lose track while doing things, for example being unable to remember why you went into a room
- go blank, for example when trying to recall your pin number
- lose track during conversations
- misplace important things, like your keys or phone
- forget words
It's normal to experience these things occasionally. For someone with functional cognitive symptoms, these things happen so often that they interfere with work and home life.
The cognitive symptoms of FND can sometimes be mistaken for dementia. Specialists will look for features that are typical of functional cognitive symptoms when diagnosing FND.
Functional speech and swallowing difficulties
Functional speech and swallowing difficulties can be a symptom of FND. You might experience:
- slurred speech
- a new stutter
- difficulties finding the right word
- unintentionally mixing words up
- whispering or hoarse speech (dysphonia)
- difficulty swallowing, including feeling like there's something stuck in your throat
A specialist will diagnose functional speech and swallowing difficulties based on specific features.
Read more about functional speech and swallowing difficulties
Persistent postural perceptual dizziness (PPPD)
PPPD (sometimes called functional dizziness, triple PD or 3PD) can be a symptom of FND.
The dizziness in PPPD is typically experienced constantly, and gets worse while walking or in crowded environments.
There are many causes of dizziness. Most people with PPPD have another cause of dizziness at the same time. A specialist will diagnose PPPD based on specific features when they assess you.
Functional visual symptoms
Visual symptoms can be a part of FND. You may experience changes to your vision, like:
- blurred vision
- double vision
- photophobia (sensitivity to light)
- reduced vision
A specialist will diagnose functional visual symptoms based on specific features that they find when they examine you.
Dissociative symptoms are common in FND, although there are many other causes. These symptoms can be hard to describe, but are often described as feeling:
- that your body is disconnected from you
- that your body doesn't belong to you
- disconnected from the world around you
- spaced out
- that you are floating
- that you are having an out-of-body experience
- there but not there
You may also be able to hear what's going on around you, but not be able to respond.
It can be helpful to know that these experiences are called dissociation and can link into other FND symptoms.
Common associated symptoms or conditions
There are other symptoms or conditions that are commonly associated with FND. These include:
- chronic pain, including fibromyalgia, back and neck pain, and complex regional pain syndrome
- persistent fatigue
- sleep problems including insomnia (not sleeping enough) and hypersomnia (sleeping too much)
- migraines and other types of headache and facial pain
- irritable bowel syndrome and other problems with the function of your stomach and bowel
- anxiety and panic attacks
- post-traumatic stress disorder
- chronic urinary retention despite all tests being normal (which may be diagnosed as Fowlers syndrome)
- dysfunctional breathing
What causes FND?
We know that the symptoms of FND happen because there's a problem with how the brain is sending and receiving messages to itself and other parts of the body. Using research tools, scientists can see that certain circuits in the brain are not working properly in people with FND.
However, there's still a lot of research to be done to understand how and why FND happens.
Why does FND happen?
FND can happen for a wide range of reasons. There's often more than one reason, and the reasons can vary hugely from person to person.
Some of the reasons why the brain stops working properly in FND include:
- the brain trying to get rid of a painful sensation
- a migraine or other neurological symptom
- the brain shutting down a part or all of the body in response to a situation it thinks is threatening
In some people, stressful events in the past or present can be relevant to FND. In others, stress is not relevant.
The risk of developing FND increases if you have another neurological condition.
Read more about how and why FND happens.
When diagnosing FND, your healthcare provider will carry out an assessment to see if there are typical clinical features of FND.
Your healthcare provider may still choose to test for other diseases and conditions before diagnosing FND. This is because many conditions share the same symptoms and, in around a quarter of cases, FND is present alongside another neurological condition. Someone can have both FND and conditions like sciatica, carpal tunnel syndrome, epilepsy, or multiple sclerosis (MS).
The diagnosis of FND, however, should be given because you have the clinical features of FND. It shouldn't be given just because there's no evidence of other conditions or illnesses.
Because the symptoms of FND are not always there, your healthcare provider may ask you to video your symptoms when they are bad so they can see what's happening to you.
FND is a really variable condition. Some people have quite short-lived symptoms. Others can have them for many years.
There are treatments available that can manage and improve FND. These treatments are all forms of rehabilitation therapy, which aims to improve your ability to carry out every day activities. Many of these treatments are designed to "retrain the brain". Some people with FND benefit a lot from treatment and may go into remission. Other people continue to have FND symptoms despite treatment.
Specialised physiotherapy can be useful in treating FND, by helping to remind the body how it should move. It can also help you build up strength and stamina you may have lost.
Occupational therapy can be helpful in treating FND. An occupational therapist will work with you to plan your treatment goals, and gradually build your confidence and ability to reach them.
Psychological therapists can help you learn to manage low mood, anxiety, and the ups and downs of an intermittent problem like FND. They can also help you gain a better understanding of your condition.
If there are traumatic events preventing your recovery, therapy focusing on that can sometimes be helpful.
Speech, language and swallowing therapy
Speech and language therapists are available to help if you're struggling with speaking or swallowing. They have a range of techniques to try, designed to help with specific problems. These might include helping you to shape certain sounds, or to practice breathing patterns as you try to talk.
Medication can play a role in treating the some of the problems associated with FND, like pain, depression and anxiety. Your healthcare provider can help decide if medication is right for you.
There are many types of medication that can make FND worse, including opiates like morphine, dihydrocodeine or codeine. It may be worth discussing your current medications with your healthcare provider.
Do not stop taking any medicine that’s been prescribed without checking with your GP or healthcare provider first, as you could make yourself very ill.
Where to find support
If you have been diagnosed with FND there are sources of information, charities and support groups that can help you.
The Neurosymptoms FND Guide has more detailed information. There is also an app available with further details about the condition.
My FND is an app that allows you to learn about your symptoms. It helps you track them, and offers advice for managing them.
FND Hope UK is a charity that raises awareness of FND. It provides further information, resources, and support services for those with FND.
FND Action is a charity that provides information on FND and support for those with a diagnosis.
Source: Scottish Government
23 February 2023
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