The term functional neurological disorder encompasses a wide range of symptoms that are often very debilitating. Doctors tend to categorise these symptoms according to their medical frame of reference, but often fail. Functional neurological disorders have no formal way of being diagnosed by doctors. They can, however, be treated.
What are functional neurological disorders?
The medical world has made some great advances in the last thirty years or so. But in recent times it has become apparent that there are a lot of symptoms out there that doctors just can't put their finger on.
When someone has problems or symptoms that don't fit into a specific diagnosis or can't be shown on a blood test or scan, doctors often use the term 'functional'. Some patients don't like this term because it can sound like they're being dismissed; however, other patients find it helpful to be given some sort of label. Patients who have been told they have functional disorders have begun to form groups to help understand their problems: this is very helpful as they can compare symptoms and help each other become aware of treatments.
Common symptoms that are experienced by people with a functional neurological disorder include:
- Tingling in the hands or feet.
- A tremor in one or both arms.
- Headaches or migraines.
- Changes in eyesight, like blurred vision or seeing flashing lights.
- Difficulty with memory or doing complicated tasks.
- Problems sleeping, including sleeping too much or too little.
- Changes to personality, like becoming more irritable or depressed.
- Seizures or shaking of the body.
- Pain in the arms or the legs that cannot be controlled by normal painkillers.
- Problems with the bowels and the bladder, like passing water more than usual or having difficulty moving one's bowels.
- Sudden fainting or loss of consciousness.
- An inability to move an arm or a leg properly, or a heavy feeling down one side of the body.
- Problems concentrating.
Specialists have found two broad sub-types that are the most common - motor problems and seizures.
The difficulty is many of these symptoms are present in other neurological conditions like Parkinson's disease, multiple sclerosis and epilepsy. That is why a doctor will usually rule out these conditions before considering a functional neurological disorder.
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What causes functional neurological disorders?
This is an area of contention because doctors can't find a definite 'cause': all blood tests, scans, and other investigations are normal. But the person certainly isn't 'making it all up': they are not malingering or faking.
One theory is that the brain, although wired up OK, doesn't control movements or receive sensations normally: hence the unusual movements like tremors, and the abnormal feelings like tingling or pain.
Many people who do not have functional neurological disorders themselves often attribute the person's symptoms to stress or emotional problems. This is valid in some cases but may be over-simplifying things. Many people with functional symptoms have had an emotional or psychological trauma in the lead-up to them developing symptoms, but others haven't. Sometimes two things coincide: a physical illness like the flu or a bad viral illness, coupled with a recent emotional trauma.
This is therefore an area where modern medicine, despite its many advances, cannot fully explain something that affects a large number of people. Another difficulty with talking about 'causes' is that the language used (with words like 'psychological', 'stress' and 'trauma') is often interpreted differently by different people.
How common are functional neurological disorders?
Doctors from almost every specialty will be familiar with patients whose symptoms do not fit a specific diagnosis or a 'box'. It is hard to quantify exactly how many people in society experience these symptoms, because many may not consult a doctor.
What is known for certain is that the symptoms are debilitating: people with functional neurological disorders rate their condition as just as devastating as people with Parkinson's disease, for example. And most family doctors, or GPs, will know how these problems can often severely affect a person's ability to live a normal life.
Functional neurological disorder treatments
Most people with functional neurological disorders find that medications do not help. It is tempting to take medications and, indeed, it is tempting for doctors to prescribe them, but each medicine carries its own set of side-effects.
Treatments generally consist of managing the symptoms and finding a way of living with them and understanding them.
Rehabilitation with physiotherapy or occupational therapy has been shown to be helpful for the more 'movement' side of functional neurological disorders, like weakness or tremors.
For the more 'sensory' type of symptoms like pain and seizures, psychotherapy and cognitive behavioural therapy can help.
In general, doctors who work in the field and patient support groups do not recommend medications for the symptoms of functional neurological disorders. An example is painkillers: many patients end up on huge quantities of pain relief which hardly ever helps; each painkiller has side-effects too and is often addictive.
Unfortunately, because conventional NHS doctors often can't help a great deal, there are a lot of practitioners with dubious qualifications out there. They often promise great cures, at vast expense. Vulnerable patients can then end up spending huge sums of money on an unattainable goal. Please be careful: try to find a reputable doctor who works in the field in a state-funded system (like the NHS) or who is covered by your insurance.
In general, the more you understand and know about functional neurological disorders, the better you can manage your symptoms. Try to find a local self-help group and meet others with the condition to find out what works for them.
What is the outlook for functional neurological disorders?
Thankfully functional disorders are now being taken more seriously by the medical world than ever before. It may be that a classification system will be set up to categorise different types of the condition. That way, treatments can be tested in trials and more can be learnt about the condition.
Further reading and references
Aybek S, Perez DL; Diagnosis and management of functional neurological disorder. BMJ. 2022 Jan 24376:o64. doi: 10.1136/bmj.o64.
Bennett K, Diamond C, Hoeritzauer I, et al; A practical review of functional neurological disorder (FND) for the general physician. Clin Med (Lond). 2021 Jan21(1):28-36. doi: 10.7861/clinmed.2020-0987.
Rommelfanger KS, Factor SA, LaRoche S, et al; Disentangling Stigma from Functional Neurological Disorders: Conference Report and Roadmap for the Future. Front Neurol. 2017 Mar 298:106. doi: 10.3389/fneur.2017.00106. eCollection 2017.
Popkirov S, Nicholson TR, Bloem BR, et al; Hiding in Plain Sight: Functional Neurological Disorders in the News. J Neuropsychiatry Clin Neurosci. 2019 Fall31(4):361-367. doi: 10.1176/appi.neuropsych.19010025. Epub 2019 May 23.