Functional Neurological Disorder (FND) is a common and disabling cause of neurological symptoms. People with FND can experience a wide variety of symptoms including:
- weakness and abnormal patterns of movement (e.g. tremor, abnormal posturing of limbs)
- attacks of abnormal movement/change in awareness that resemble epileptic seizures
- sensory problems
- cognitive problems
- visual and speech symptoms
Whilst the symptoms may appear similar to neurological diseases including those of Multiple Sclerosis, Parkinson’s and Epilepsy, and can be just as disabling, they are not caused by structural disease of the nervous system, but instead are a problem with the “functioning” of the nervous system.
People with FND appear to lose the ability to control or access their body normally. The “basic wiring” of the nervous system is intact, but when people with FND try to use it to move, feel or think, they cannot get access to it normally. FND is not a problem with motivation, and symptoms are not imagined or “put on”. It is a specific diagnosis, and not simply a diagnosis that is used when tests are normal or no better explanation can be found. Specific features on clinical history and examination, and occasionally tests, are used to make the diagnosis.
FND overlaps both neurology and psychology, and this is reflected in the confusing array of names that are used to describe FND. As understanding of functional neurological symptoms has advanced, so has the debate among medical professionals regarding the diagnostic criteria and terminology as can be seen with reference to the 11th revision of the World Health Organisation’s International Classification of Diseases (ICD-11).
Historially, past trauma was thought to be the only factor that influenced the development of functional neurological symptoms, but research findings indicated this is not the case for everyone with an FND diagnosis. It seems that a number of factors, different between different people, can be involved in making people more vulnerable to developing FND and for triggering and maintaining the condition.
FND is a treatable condition, but, similarly to many illnesses, not everyone with FND will benefit from treatment and some people remain with persistent symptoms. Treatment is generally with specialist rehabilitation, which, depending on the person and their symptoms, can include input from specialist physiotherapy, clinical psychology, occupational therapy, psychiatry, pain management specialist and neurology.
(Edited by Professor Mark Edwards, Movement Specialist at St George’s, University of London Atkinson Morley Regional Neuroscience Centre)
To read further about functional neurological symptoms please visit www.neurosymptoms.org, which is a patient guide website written by Dr Jon Stone, Consultant Neurologist and Honorary Reader in Neurology, University of Edinburgh
CLICK HERE for information about symptoms.
 Functional disorders in the Neurology section of ICD-11: A landmark opportunity
Stone J, Hallett M, Carson A, Bergen D, Shakir R. Neurology. 2014;83(24):2299-2301. doi:10.1212/WNL.0000000000001063.