If symptoms are new, sudden, severe, or unlike your usual FND pattern, seek urgent medical help.Urgent help
FND Connect CIC

What is Functional Neurological Disorder?

FND is a problem with how the nervous system is working. Symptoms are real, involuntary and can be disabling, even when standard tests do not show structural damage that explains them.

Short version: FND affects the way the brain and body send, receive and process signals. It is often described as a “software” problem rather than damage to the “hardware” of the nervous system.

FND is real

FND is not a person “putting it on”, being weak, or choosing to have symptoms. The symptoms happen at a level of nervous system control that a person cannot simply override. People can want to move, speak or stay aware and still find that their body does not respond as expected.

Modern understanding describes FND as a disorder of function and brain networks. That means the structure of the brain, spinal cord and nerves may look normal on routine scans, while the way those networks are operating is disrupted.

How FND is diagnosed

A good FND diagnosis should be based on positive clinical features seen by a neurologist or suitably trained specialist. It should not be a diagnosis given only because a scan or blood test is normal.

Positive signsFeatures on examination that are typical of FND, such as movement that improves with distraction or automatic movement that is better than deliberate movement.
TestingTests may still be needed to check for other conditions. FND can also exist alongside epilepsy, migraine, MS, injury, pain conditions or other illnesses.

Why does FND happen?

There is no single cause that fits everyone. FND can follow illness, injury, surgery, migraine, pain, stress, trauma or another neurological condition. For some people psychological stress is relevant; for others it is not. The key point is that symptoms are produced by changes in nervous system function, not by blame or personal failure.

Why people experience different things

FND can affect movement, sensation, speech, swallowing, vision, awareness, balance, cognition and other body systems. One person may mainly have leg weakness. Another may have functional seizures. Another may have tremor, pain, fatigue and brain fog. Symptoms can also change over time.

This variation is one reason people often feel isolated after diagnosis. It is also why treatment should be individualised around the symptoms, triggers, goals and life circumstances of the person in front of the clinician.

Helpful language

  • “Functional” means a problem with how the nervous system functions; it does not mean the person can function normally.
  • “Normal scan” does not mean “nothing is wrong”; it means the scan has not shown structural damage explaining the symptom.
  • “Retraining” is not the same as telling someone to try harder. It means using targeted rehabilitation to help the brain and body rebuild more reliable patterns.

Sources and further reading