Functional Disorders



Functional disorders are disorders at the interface of psychiatry and medicine.

Around 15% of new patients in UK neurology clinics have symptoms that are functional or dissociative.

Functional and dissociative neurological symptoms have been given different names over the years including Conversion Disorder, Psychogenic, Non-organic, Psychosomatic, Somatisation disorders.

Functional neurological disorder (FND) is caused by problems with the functioning of the nervous system - a ‘software’ rather than a ‘hardware’ problem.

Signs and symptoms

Functional neurological disorder is an umbrella term for symptoms such as limb weakness, numbness, tremor, blackouts, visual symptoms, cognitive symptoms and dissociative seizures. 

Individuals may have functional neurological symptoms in isolation or combination – most have more than one symptom. 

Common associated symptoms include fatigue, pain, headache, sleep problems, worry/panic, low mood, IBS and complex regional pain syndrome. 

It is quite common for people to have FND as well as another neurological condition. 

A big problem that people with functional and dissociative symptoms encounter is feeling that they are not believed by health professionals. It is important to appreciate that symptoms are not imagined and can be very disabling.


Normally a neurologist will assess someone with suspected FND and make the diagnosis. 

There is no imaging or blood test that can confirm the diagnosis, however FND is not a diagnosis of exclusion, and positive signs (like Hoovers sign, tremor entrainment test or typical features if a functional seizure) should be identified that indicate a functional problem. 

As a foundation doctor, you are likely to encounter patients with FND in the general hospital and/or primary care so it is important that you have an understanding of it and seek support from senior colleagues in neurology and/or psychiatry where necessary and depending on local service arrangements. 


  • Supporting the patient to understand the diagnosis, typically by demonstrating positive features, is an important starting point
  • Depending on the primary symptoms, a combination of the following approaches may be helpful:
    • Physiotherapy/exercise
    • Occupational therapy
    • Psychological therapy
    • Speech and language therapy
    • Medication. Antidepressants can sometimes help with sleep, pain, low mood and worry. 


Here is a link to, a resource for patients and professionals with lots of fantastic information on FND, authored by Professor Jon Stone. 

Functional Neurological Disorder (FND) – A Patient's Guide to FND (

Last reviewed: 21/02/2024

Next review date: 21/08/2024

Author(s): Medical Education Fellow, NHS Lothian.

Author email(s):

Reviewer name(s): Medical Education Fellow, NHS Lothian.