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.
Common associated symptoms or conditions
There are other symptoms or conditions that are commonly associated with FND. These include:
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.
Read more about treating FND
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.