Functional neurological disorder

Functional neurological disorder (FND) is a problem with how the brain receives and sends information to the rest of the body.

It helps to think of your brain as a computer. In someone with FND, there's no damage to the hardware, which is the structure of the brain. The software, the program running on the computer, isn't working properly.

The problems behind FND happen at a level of the brain that you cannot control. They include symptoms like arm and leg weakness and seizures. Other symptoms, such as fatigue or pain, are not directly caused by FND, but they are often found alongside it.

Functional neurological disorder (FND) can cause many different symptoms, and they vary from person to person. Some people have only a few symptoms, and others have many.

A doctor should diagnose FND because you have one or more clinical features that a specialist can recognise as typical of it. The diagnosis shouldn't be made just because scans or tests for other neurological conditions with similar symptoms come back normal.

A clinical feature is a distinctive way a symptom shows itself, one that is unique to FND. For example, your eyes may close during seizures, or limb weakness may briefly disappear during certain physical tests. Specialists use these features to tell FND apart from other neurological conditions with similar symptoms.

Functional limb weakness is when a leg or an arm does not work properly. In FND, this happens because of a problem with how the nervous system is functioning. It can cause symptoms such as:

• problems walking
• heaviness down one side
• dropping things
• feeling like a limb isn't part of you

Functional limb weakness can often look like 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 it from 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 their awareness of their surroundings, or their ability to interact with them. 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 know when a seizure is about to happen, while others have them without warning. A specialist will ask you and your friends or family what happens during a seizure, and will look at any video footage you can provide. They use this evidence to decide whether 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 through the day, and it can change in speed and strength. A specialist will diagnose it from specific features of your symptoms that they find when they examine you.

Functional dystonia is a type of muscle spasm. It makes a part of the body become stuck in an unusual position, for a short or a long period of time. Someone with functional dystonia will often have curled fingers, a clenched hand, or an ankle that turns in.

Functional gait disorder describes the problems with walking that you may have 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 it from clinical features, such as the way your walking changes when you do different activities.

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 mouth or jaw being pulled 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, and they 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.

Jerks or twitches, which are sudden movements, can also be a symptom of FND. Everyone has random jerks now and then, like when you jolt awake as you're falling asleep. In FND, though, these uncontrolled jerks and twitches can become much more frequent.

Functional drop attacks are when someone falls to the ground suddenly, without losing consciousness.

Numbness, pins and needles, or a feeling that a limb isn't part of your body can also be symptoms of FND.

Problems with your memory or concentration can be a symptom too. 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 have these experiences occasionally. For someone with functional cognitive symptoms, they happen so often that they interfere with work and home life. These symptoms can sometimes be mistaken for dementia, so specialists look for features that are typical of functional cognitive symptoms when diagnosing FND.

Functional speech and swallowing difficulties can be a symptom of FND. You might have:

• 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 these difficulties based on specific features.

PPPD (sometimes called functional dizziness, triple PD or 3PD) can be a symptom of FND. The dizziness in PPPD is typically constant, and it gets worse while walking or in crowded places. There are many causes of dizziness, and most people with PPPD have another cause of dizziness at the same time. A specialist will diagnose PPPD from specific features when they assess you.

Visual symptoms can be part of FND. You may notice changes to your vision, like:

• blurred vision
• double vision
• photophobia (sensitivity to light)
• reduced vision

A specialist will diagnose functional visual symptoms from specific features that they find when they examine you.

Dissociative symptoms are common in FND, although they have many other causes too. They can be hard to describe, but people often say they feel:

• 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. These experiences are called dissociation, and they can link into other FND symptoms.

Some other symptoms or conditions are commonly linked 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
• depression
• post-traumatic stress disorder
• chronic urinary retention despite all tests being normal (which may be diagnosed as Fowlers syndrome)
• dysfunctional breathing

Doctors know that the symptoms of functional neurological disorder (FND) happen because something goes wrong with the way the brain sends and receives messages, both to itself and to other parts of the body. Research tools let scientists see that certain circuits in the brain are not working properly in people with FND.

There is still a lot of research to be done before we understand how and why FND happens.

Functional neurological disorder (FND) can happen for many different reasons. Often there's more than one, and the reasons can differ hugely from one person to the next.

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 psychological stress or a situation it thinks is threatening

For some people, stressful events in the past or present can be relevant to FND. Psychological conditions like PTSD, depression or anxiety can be relevant too. In other people, none of these things play a part.

Your risk of developing FND goes up if you have another neurological condition. It may also go up if you have a condition like autism or attention deficit hyperactivity disorder (ADHD).

To diagnose functional neurological disorder (FND), your doctor will assess you to see whether you have the typical clinical features of FND.

The doctor may still test for other diseases and conditions first. 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.

The symptoms of FND are not always there, so your doctor may ask you to video them. That lets the doctor see what your symptoms look like.

Functional neurological disorder (FND) varies a lot from one person to the next. Some people have symptoms that pass fairly quickly. Others live with them for many years.

There are treatments that can manage and improve FND. All of them are forms of rehabilitation therapy, which helps you get back your ability to do everyday activities. Many of them work by "retraining the brain". Some people with FND gain a great deal from treatment and may go into remission. Others still have symptoms despite treatment.

Specialised physiotherapy can be useful. It helps remind the body how it should move, and it can help you build up strength and stamina you may have lost.

Occupational therapy can help too. An occupational therapist will work with you to plan your treatment goals, then gradually build your confidence and your ability to reach them.

Psychological therapy can help many people with FND, even those who don't have stress in their lives. It can give you a better understanding of FND and how it relates to your personal circumstances.

Some psychological techniques are aimed specifically at helping you gain better control over movement or seizure symptoms. Psychological therapy can also help you learn to manage low mood, anxiety and past traumatic events, as well as other psychological problems (if present). Not everyone with FND will need it.

Speech and language therapists can help if you're struggling with speaking or swallowing. They have a range of techniques to try for specific problems. These might include helping you shape certain sounds, or practise breathing patterns while you talk.

Medicine can help with some of the problems linked to FND, such as pain, depression and anxiety. Your doctor can help decide if medicine is right for you.

Many types of medicine can make FND worse, including opiates like morphine, dihydrocodeine or codeine. It may be worth discussing your current medicines with your doctor.

Don't stop taking any medicine that's been prescribed for you without checking with your doctor first. You could make yourself very ill.

Read more about treating FND

Functional neurological disorder (FND) is broadly the same condition in children and young people as it is in adults. It's unusual for it to start before the age of 10, but it becomes more common through the teenage years.

Treatment for FND in children and young people is similar to treatment in adults. Families and schools especially need to learn about the condition, so they can respond in the most helpful way.