Functional movement disorder

Functional movement disorder is a type of Functional Neurological Symptom Disorder, which means there are physical symptoms similar to those found in neurological disorders, but it is classed as neuropsychiatric / psychiatric in origin. The symptoms are physical, but also incompatible with any known neurological or medical condition. The symptoms can include such symptoms as weakness or paralysis, abnormal movements like tremor or dystonic movements, gait abnormalities, and abnormal limb posturing. There may or may not be a known psychological stressor linked to the symptoms.

Signs and Symptom Types

Symptom type (DSM-5)	Alternative names	Similar ME/CFS Symptoms
weakness or paralysis	Dissociative Motor Disorders, Psychogenic movement disorder, Functional Movement Disorder	paralysis,muscle weakness, paresis
abnormal movement (e.g., tremor, dystonie movement, myoclonus, gait disorder)	Dissociative Motor Disorders, Psychogenic movement disorder, Psychogenic tremor	muscle fasciculations (twitching), dystonia, myoclonus (jerking movements), ataxia (gait problems), dysphasia, vertigo
speech symptoms (e.g., dysphonia, slurred speech)	Dissociative Motor Disorders	facial paralysis, word-finding difficulties, brain fog / cognitive dysfunction
swallowing symptoms	Dissociative Motor Disorders (e.g., ataxia), Psychogenic movement disorder, Psychogenic aphonia, Psychogenic dysphonia	dysphagia, partial paralysis / paresis - may also include chewing problems
attacks or seizures	Dissociative convulsions, pseudoseizures, psychological non-epileptic seizures (PNES), Non-epileptic attack disorder (NEAD), dissociative stupor	seizure-like symptoms, sleep paralysis or unconsciousness in very severe ME
anaesthesia or sensory loss	Dissociative Anaesthesia or Sensory Loss, Psychogenic deafness, Psychogenic blindness	numbness, paresthesia
special sensory symptoms (e.g., visual, olfactory, or hearing distur­bance)	Conversion disorder, Medically unexplained neurological symptoms	Visual dysfunction, double vision, blurred vision, nystagmus, photophobia, hyperacuity (hearing sensitivity), tinnitus, aural problems, altered sense of smell
Mixed symptoms	Dissociative disorders of movement and sensation, Mixed dissociative [conversion] disorders, Functional Neurological Symptom Disorder, Functional Neurological Symptom, Conversion Disorder, Dissociative Neurological Symptom Disorder, Functional Neurological Disorder (FND), Conversion Hysteria (historical name), Medically unexplained neurological symptoms, MUPS/MUS

Physical Symptoms

Functional Neurological Symptom Disorder (FNSD or FND) is a poorly understood disorder. 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 Symptom Disorder arises from a problem with the patient's Central Nervous System, which is not sending or receiving signals correctly. The brain of a patient with Functional Neurological Symptom Disorder is structurally normal, but functions incorrectly. MRI and CT scans 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" (meaning not under voluntary control), and cause physical disability or distress to the individual. It is widely accepted that those with FND may be as disabled as those with Multiple Sclerosis or Parkinsons, and often are more distressed.

The term Conversion Disorder is still used by some clinicians, however refers specifically to those who have a psychological stressor causing their symptoms, such as a traumatic event or mental conflict. It 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"

Diagnostic labeling is causing a great amount of confusion amongst patients and doctors alike. One doctor may use the term Functional Neurological Disorder or Functional Movement Disorder, but then another may use Conversion Disorder.

History of FND

FND has historically been highly stigmatized, with patients often referred to as hysterics, or hysterical (based on its original name of Hysteria). The first evidence of FNSD dates back to 1900 BC, where the symptoms were blamed on the uterus moving around within the female body. The treatment was based on placing a mix of unpleasant and pleasant odors around the body in the belief that this would encourage the uterus to return to its proper position.

In Greek mythology, hysteria, the original name for a group of conditions including FND, was thought to be caused by a lack of orgasms, uterine melancholy and childlessness. Remedies included orgies and marriage. From the 13th Century, women with hysteria were exorcised, as it was believed that if doctors could not find the cause of a disease or illness, it must be caused by the devil. This was in keeping with the belief at the time that mental illness was a spiritual / demonic problem.

Between the late 16th century and the 18th century the role of the uterus was no longer central to the disorder, with Thomas Willis discovering that the brain and central nervous system were the cause of the symptoms. Thomas Sydenham argued that the symptoms of may have an organic (physical) cause and proved that the uterus was not the cause of symptoms.

From the 18th century, there was a move toward the idea that hysteria was caused by the brain. This led to an understanding that it could affect both sexes. Jean Martin Charcot argued that hysteria was caused by "a hereditary degeneration of the nervous system, namely a neurological disorder".

In the 19th Century, hysteria moved from being considered a neurological disorder to being considered a psychological disorder, when Pierre Janet argued that "dissociation appears autonomously for neurotic reasons, and in such a way as to adversely disturb the individual’s everyday life"

Freud referred to hysteria as conversion disorder. He believed that those with the condition could not live in a mature relationship, and that those with the condition were unwell in order to achieve a 'secondary gain' in that they are able to manipulate their situation to fit their needs or desires. He also found that both men and women could suffer with the disorder.

In 2013, the Diagnostic and Statistical Manual of Mental Disorders version 5 (DSM-5) kept the name Conversion Disorder, however it included Functional Neurological Symptom Disorder as an alternative name. In the 2022 revision of the DSM-5, the DSM-5-TR, the primary name was changed to Functional Neurological Symptom Disorder, however Conversion Disorder was still kept as an alternative name.

Today, there is growing evidence that psychological stress is not necessarily the cause of FND. A recent study by the charity FNDHope found that psychological triggers affected only 30% of patients. Some doctors still follow Freud's theory about Conversion Disorder, however others are moving on to look at the role of the Central Nervous System in FNSD symptoms.

Signs and Symptoms

There are a great number of symptoms experienced by those with Functional Neurological Disorder. It is important to note that all the symptoms which are experienced by those with FNsD are real, and often debilitating. 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-5

Functional Neurological Symptom Disorder was added to the DSM-5 to replace the term 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. However, some doctors are advising the discontinuation of the term 'Conversion Disorder' entirely.

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.

Specify if:

• Psychological Stressor
• No Psychological Stressor

Treatments

Treatment Options

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% improvement rate across patients with both FND and CD, however is effective mainly in those with Conversion Disorder as opposed to Functional Neurological Disorder. For those with Conversion Disorder, or with a psychological trigger to their symptoms, psychological treatments have been found not to be a cure, as "‘ ... psychosocial treatments have not yet been shown to have a lasting and clinically meaningful influence on the physical complaints of polysymptomatic somatisers’ (Allen et al, 2002)."

Treatment options can include:

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

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

Some, but not all patients with FNsD may experience low moods or anxiety due to their condition. However often they will not seek treatment due being worried that a doctor will blame their symptoms on their anxiety or depression.

Prevalence

Functional Neurological Disorder is a common problem, with estimates suggesting that up to a third of neurology outpatients having functional symptoms. In Scotland, around 5000 new cases of FND are diagnosed annually. 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.

Common Myths about Functional Neurological Symptom Disorder

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 Symptom Disorder

Functional Neurological Symptom Disorder only affects females

Functional Neurological Symptom Disorder only affects young adults

Functional Neurological Symptom Disorder is rare

Research

Currently, little research is being carried out into Functional Neurological Disorder, with most research focusing on symptoms caused by Conversion Disorder. This research focuses on Freudian ideas and the theory that patients attitudes towards their illness directly correlate with the continuation of symptoms.

Researchers studying Functional Neurological Symptom Disorder without psychological stressors are looking at various possible causes including

• Neurotoxicity
• Central Sensitization Syndrome

Debate

There is much debate surrounding the FND diagnosis. Some doctors continue to believe that all FND patients have unresolved traumatic events (often of a sexual nature) which are being expressed in a physical way. However, some doctors do not believe this to be the case. Wessely and White state that all somatic illnesses, including Fibromyalgia, Irritable Bowel Syndrome and Chronic Fatigue Syndrome "still fall under the title of ‘unexplained’ since no consensual scientific explanation has been advanced for any of them that meets with universal acceptance. Unexplained means what it says on the tin, and is not a code for psychiatric, still less for ‘all in the mind’." They go on to argue that "A somatoform disorder can only be so classified in the absence of an adequate physical explanation (World Health Organization, 1992). Furthermore, a somatoform pain disorder can only ‘... occur in association with emotional conflict or psychosocial problems that are sufficient to allow the conclusion that they are the main causal influences’ (World Health Organization, 1992). How can the clinician be sure that the psychosocial problem actually caused the illness?"

Alternative Diagnoses

Functional Neurological Symptom Disorder can mimic many other conditions. Although doctors state that misdiagnosis rates are very low, with some research suggesting that only 2% of patients were misdiagnoses after 12.5 years. Some alternative diagnoses for FNsD can be

• Hemiplegic migraine
• Multiple sclerosis
• Amyotrophic literal sclerosis (ALS/Motor Neurone Disease)
• Parkinson's disease
• Autoimmune Disorders
• Ehlers Danlos Syndrome
• Stroke

Other Functional Conditions

• Irritable Bowel Syndrome (IBS)
• Fibromyalgia
• Chronic Pelvic Pain (CPP)
• Interstitial cystitis (IC)
• Temporomandibular joint disorder (TMJ)

Notable studies

• 2012, Functional (psychogenic) movement disorders

Learn more

neurosymptoms.org

| ICD10 blue book, p127

FND Hope

DSM-5 (Google books preview)

See also

• Nonepileptic seizure
• Myalgic encephalomyelitis
• International Consensus Criteria for ME/CFS
• Cognitive behavioral therapy
• Medically unexplained symptoms
• Psychologization