Functional neurological disorder: when the software is the problem.

Seizures without epilepsy. Weakness without stroke. Tremor without Parkinson's. All real, all treatable, and badly explained for a hundred years.

This page is about living with the condition, not diagnosing it. The clinical details are a summary of mainstream understanding; your own clinicians know your case.

The usual way of explaining FND goes like this. The nervous system has hardware and software. In stroke, multiple sclerosis, or epilepsy, the hardware is damaged, and scans show it. In FND, the hardware is intact and the software has a problem: the brain is sending and receiving signals in a way that produces real symptoms without any structural disease. The computer is fine. The program has crashed.

It is an imperfect analogy, but it captures the two things people with FND most need to hear. The symptoms are real and not imagined. And because the problem is in function rather than structure, it can change.

What FND looks like

FND produces almost any neurological symptom:

• Functional seizures (also called dissociative or non-epileptic seizures): episodes that look like epileptic seizures but have a different mechanism and do not show epileptic activity on EEG.
• Functional weakness or paralysis of a limb or one side of the body.
• Functional movement disorders: tremor, jerks, dystonia, abnormal gait.
• Sensory symptoms: numbness, tingling, visual disturbance.
• Speech and swallowing problems, dizziness, and cognitive symptoms.

It is common, accounting for a substantial share of new neurology referrals, and it often coexists with chronic pain, fatigue, and anxiety.

How it is diagnosed

FND used to be a diagnosis of exclusion: everything else ruled out, so it must be this. That approach left patients feeling fobbed off. Modern diagnosis is made on positive signs: specific clinical findings that show the nervous system is capable of normal function when attention is directed elsewhere. In functional leg weakness, for example, the leg may push down strongly when the person is asked to lift the other leg, even though it cannot push on request. In functional tremor, the tremor changes frequency or stops when the person taps a rhythm with the other hand. These signs are reliable and are the basis for a confident diagnosis, not a shrug.

A good neurologist will show you the signs, because seeing your own leg move normally is part of the treatment.

What causes it

FND is best understood as a problem of prediction and attention. The brain runs on predictions about what the body is doing and about to do. In FND those predictions become fixed in a way that overrides normal movement, and attention directed at the body makes it worse: the harder you try to move the leg, the less it moves. Triggers vary. Injury, illness, pain, exhaustion, and stressful events can all precede it. Past trauma is a risk factor for some people but not all, and the old assumption that FND always reflects hidden psychological conflict is no longer held. Our handbook on the predictive brain covers the science of prediction in detail.

What helps

• Understanding the diagnosis. This is treatment, not a preamble. People who understand what FND is and believe the diagnosis do better. Resources like neurosymptoms.org, written by neurologists, are often where this starts.
• Specialist physiotherapy. For motor symptoms, physiotherapists trained in FND use techniques that redirect attention away from the body and retrain automatic movement, often with striking results.
• Psychological therapy. CBT and ACT help with the fear and vigilance that maintain symptoms, with coexisting anxiety and depression, and, for functional seizures, with recognizing and managing the warning signs.
• Treating what travels with it. Pain, fatigue, sleep problems, and mood are addressed alongside.

What the research says

Psychological treatment for FND has a thinner evidence base than it should, and ACT is one of the approaches being tested to improve it. A UK case series gave eight people with a range of FND symptoms, including limb paralysis, sensory loss, and fainting, a brief course of six to ten ACT sessions aimed at reducing symptom interference through psychological flexibility, with encouraging results. A randomized feasibility trial of online group ACT for functional cognitive disorder has been completed, and a larger NHS study of ACT for FND is registered. Clinical reports describe ACT used for functional seizures in adults and adolescents, where its refusal to make claims about cause, combined with its focus on living well in a difficult situation, seems to suit people who have been alienated by older explanations. The fair summary: promising, consistent with the mechanism, and awaiting larger trials.

How ACT helps

FND feeds on attention and fear. A person watching their leg, bracing for the tremor, scanning for the aura, is directing exactly the kind of attention that keeps the software stuck. ACT's skills run the other way.

Present-moment skills, particularly grounding exercises like dropping anchor, widen attention out from the body to the room. For functional seizures, grounding at the first warning sign is a core technique.

Defusion loosens the thoughts that drive vigilance: “it's going to happen,” “my leg is going to give way,” “I can't trust my body.” These thoughts are predictions, and in FND, predictions have unusual power over the body. Holding them lightly matters.

Acceptance is about letting symptoms be present without the struggle that amplifies them. Trying hard to stop a functional tremor makes it worse; allowing it, while attending elsewhere, often lets it settle.

Values and committed action address the avoidance. People with FND often withdraw from work, driving, social life, and exercise out of fear of symptoms occurring. A gradual, valued return, with willingness to have some symptoms along the way, is both the path back to life and part of the treatment, because activity directed by values rather than by symptom-watching is the state in which the software works best.

Cindra is not a treatment for FND and does not replace specialist care. What it can do is support the daily practice: grounding when warning signs appear, defusion from the predictions, paced valued activity, and a record of patterns you can share with your team.

This article is for general education and is not medical advice. Chronic pain deserves a proper assessment. If your pain is new, changing, or comes with red-flag symptoms like numbness, weakness, fever, or loss of bladder or bowel control, see a clinician promptly.