Functional Neurological Disorder

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Functional Neurological Disorder is a neurological disorder for which very little is currently known. It is an umbrella term for a variety of symptoms which look similar to those caused by neurological conditions such as Multiple Sclerosis (MS) or Parkinson's Disease, including weakness, fatigue and seizures. It is currently believed that Functional Neurological Disorder arises from a problem with the patient's Central Nervous System, which is not sending and receiving signals correctly.[1] The brain of a patient with Functional Neurological Disorder is structurally normal, however functions incorrectly.[2]

Currently, traditional tests and investigations such as blood tests, MRI and CT scans will show no abnormalities in patients with FND, however it has been discovered that there is a difference in blood flow to certain key areas of the brain when scanned using Functional Magnetic Resonance Imaging (fMRI). Although currently there is no way to 'see' whether a patient has FND, their symptoms are real, and often cause disability and distress to the individual.[3]

Functional Neurological Disorder is similar to the condition Conversion Disorder (CD), which also causes various neurological symptoms. Conversion Disorder however, is "a psychoanalytic concept that describes the occurrence of motor or sensory neurological symptoms other than pain and fatigue that cause distress, are not explained by disease, not malingered but are thought to relate to psychological factors"[4]

Signs and Symptoms[edit]

There are a great number of symptoms experienced by those with Functional Neurological Disorder. These include, but are not limited to

  • Weakness
  • Paralysis
  • Dizziness
  • Nausea
  • Changes in vision
  • Non-epileptic seizures
  • Blackouts
  • Tremors
  • Fatigue
  • Chronic pain
  • Sensory abnormalities
  • Bladder or bowel changes


Diagnostic Criteria from DSM-V[edit]

Functional Neurological Symptom Disorder was added to the DSM-V to replace Conversion Disorder. There are two subcategories of Functional Neurological Symptom Disorder, those with a psychological stressor and those without. Functional Neurological Disorder is the widely accepted term for those without, while Conversion Disorder refers to those with a psychological stressor.

The diagnostic criteria for Functional Neurological Disorder is:

A. The patient has ≥1 symptoms of altered voluntary motor or sensory function.

B. Clinical findings provide evidence of incompatibility between the symptom and recognised neurological or medical conditions.

C. The symptom or deficit is not better explained by another medical or mental disorder.

D. The symptom or deficit causes clinically significant distress or impairment in social, occupational, or other important areas of functioning or warrants medical evaluation.

Specify type of symptom or deficit as:

  • With weakness or paralysis
  • With abnormal movement (e.g., tremor, dystonic movement, myoclonus, gait disorder)
  • With swallowing symptoms
  • With speech symptoms (e.g., dysphonia, slurred speech)
  • With attacks or seizures
  • With anaesthesia or memory loss
  • With special sensory symptom (e.g., visual, olfactory,or hearing disturbance)
  • With mixed symptoms.

Specify if:

  • Acute episode: symptoms present for less than 6 months
  • Persistent: symptoms present for 6 months or more.[5]

No Psychological Stressor


Treatment Options[edit]

A multi-disciplinary approach to treating Functional Neurological Disorder is recommended. There is currently no known cure for the condition, however some treatment options have had low-level success rates. For example, Cognitive Behavioural Therapy (CBT) has a 13% success rate across patients with both FND and CD,[6] however is effective mainly in those with Conversion Disorder as opposed to Functional Neurological Disorder.

Treatment options can include:

  • Physiotherapy[7]
  • Neurological Rehabilitation Centres
  • Medication such as sleeping tablets, painkillers, anti-epileptic medications and anti-depressants[8]
  • Psychological support which can help patients to understand their condition or support them when they experience low moods or anxiety[9]

However for many patients with FND, accessing treatment can be difficult as availability is limited. Most medical professionals are unaware of how to treat patients with functional symptoms.[10]


Functional Neurological Disorder is a common problem, with estimates suggesting that up to a third of neurology outpatients having functional symptoms.[10] In Scotland, around 5000 new cases of FND are diagnosed annually.[10] Furthermore, non-epileptic seizures account for 1 in 7 referrals to neurologists after an initial seizure, and functional weakness has a similar prevalence to Multiple Sclerosis.[10]

Common Myths about Functional Neurological Disorder[edit]

Patients are imagining their symptoms

Patients are feigning their symptoms

Functional Neurological Disorder is caused by psychological dysfunction or a problem with emotional processing

Cognitive Behavioural Therapy (CBT) will cure Functional Neurological Disorder


Currently, little research is being carried out into Functional Neurological Disorder, with most research focusing on symptoms caused by Conversion Disorder.

Other Functional Conditions[edit]



  1. ^ a b "". Retrieved 2015-11-24. 
  2. ^ "Functional Neurological Symptoms | Neurology in NHS Greater Glasgow and Clyde". Retrieved 2015-11-24. 
  3. ^ Carson, Alan J.; Ringbauer, Brigitte; Stone, Jon; McKenzie, Lesley; Warlow, Charles; Sharpe, Michael (2000). "Do medically unexplained symptoms matter? A prospective cohort study of 300 new referrals to neurology outpatient clinics". Journal of Neurology, Neurosurgery and Psychiatry 68 (2): 207–210. 
  4. ^ Stone, Jon; Carson, Alan; Sharpe, Michael (2005). "Functional symptoms and signs in neurology: assessment and diagnosis". Journal of Neurology, Neurosurgery and Psychiatry 76 (1). 
  5. ^ "Conversion and somatic symptom disorders". Retrieved 25 November 2015. 
  6. ^ "Symptoms - FND Hope". FND Hope (in en-US). Retrieved 2015-11-25. 
  7. ^ "". Retrieved 2015-11-25. 
  8. ^ "". Retrieved 2015-11-25. 
  9. ^ "". Retrieved 2015-11-25. 
  10. ^ a b c d "Neurological functional symptoms stepped care report". Retrieved 2015-11-25. 
  11. ^ "IBS and Non-GI Functional Disorders -". Retrieved 2015-11-25.