Functional neurologic disorder

Last updated
Functional Neurologic Disorder
Specialty
Symptoms Numbness, weakness, non-epileptic seizures, tremor, movement problems, trouble speaking, fatigue
Usual onsetAges 20 to 40
Risk factors
Differential diagnosis Multiple sclerosis
Treatment
Medication

Functional neurologic disorder or functional neurological disorder (FND) is a condition in which patients experience neurological symptoms such as weakness, movement problems, sensory symptoms, and convulsions. As a functional disorder, there is, by definition, no known disease process affecting the structure of the body, yet the person experiences symptoms relating to their body function. Symptoms of functional neurological disorders are clinically recognisable, but are not categorically associated with a definable organic disease. [1] [2]

Contents

The intended contrast is with an organic brain syndrome, where a pathology (disease process) which affects the body's physiology can be identified. Subsets of functional neurological disorders include functional neurologic symptom disorder (FNsD) (conversion disorder), functional movement disorder, and functional seizures. The diagnosis is made based on positive signs and symptoms in the history and examination during consultation of a neurologist. [3]

Physiotherapy is particularly helpful for patients with motor symptoms (weakness, gait disorders, movement disorders) and tailored cognitive behavioural therapy has the best evidence in patients with non-epileptic seizures. [4] [5]

History

From the 18th century, there was a move from the idea of FND being caused by the nervous system. This led to an understanding that it could affect both sexes. Jean-Martin Charcot argued that, what would be later called FND, was caused by "a hereditary degeneration of the nervous system, namely a neurological disorder". [6]

In the 18th century, the illness was confirmed as a neurological disorder but a small number of doctors still believed in the previous definition. [6] However, as early as 1874, doctors, including W.B. Carpenter and J.A. Omerod, began to speak out against this other term due to there being no evidence of its existence. [7]

Although the term "conversion disorder" has been used for many years, another term was still being used in the 20th century. However, by this point, it bore little resemblance to the original meaning. It referred instead to symptoms that could not be explained by a recognised organic pathology, and was therefore believed to be the result of stress, anxiety, trauma or depression. The term fell out of favour over time due to the negative connotations. Furthermore, critics pointed out that it can be challenging to find organic pathologies for all symptoms, and so the practice of diagnosing that patients who had such symptoms were imagining them led to the disorder being meaningless, vague and a sham-diagnosis, as it did not refer to any definable disease. [7]

Throughout its history, many patients have been misdiagnosed with conversion disorder when they had organic disorders such as tumours or epilepsy or vascular diseases. This has led to patient deaths, a lack of appropriate care and suffering for the patients. Eliot Slater, after studying the condition in the 1950s, was outspoken against the condition, as there has never been any evidence to prove that it exists. He stated that "The diagnosis of 'hysteria' is a disguise for ignorance and a fertile source of clinical error. It is, in fact, not only a delusion but also a snare". [7]

In 1980, the DSM III added 'conversion disorder' to its list of conditions. The diagnostic criteria for this condition are nearly identical to those used for hysteria. The diagnostic criteria were:[ citation needed ]

A. The predominant disturbance is a loss of or alteration in physical functioning suggesting a physical disorder. It is involuntary and medically unexplainable

B. One of the following must also be present:

  1. A temporal relationship between symptom onset and some external event of psychological conflict.
  2. The symptom allows the individual to avoid unpleasant activity.
  3. The symptom provides opportunity for support which may not have been otherwise available.

Today, there is a growing understanding that symptoms are real and distressing, and are caused by an incorrect functioning of the brain rather than being imagined or made up. [8]

Signs and symptoms

There are a great number of symptoms experienced by those with a functional neurological disorder. While these symptoms are very real, their origin is complex, since it can be associated with severe psychological trauma (conversion disorder), and idiopathic neurological dysfunction. [9] The core symptoms are those of motor or sensory dysfunction or episodes of altered awareness: [10] [11] [12] [13]

Causes

A systematic review found that stressful life events and childhood neglect were significantly more common in patients with FND than the general population, although some patients report no stressors. [14]

Converging evidence from several studies using different techniques and paradigms has now demonstrated distinctive brain activation patterns associated with functional deficits, unlike those seen in actors simulating similar deficits.  [15] The new findings advance current understanding of the mechanisms involved in this disease, and offer the possibility of identifying markers of the condition and patients' prognosis. [16] [17]

FND has been reported as a rare occurrence in the period following general anesthesia. [18]

Diagnosis

A diagnosis of a functional neurological disorder is dependent on positive features from the history and examination. [19]

Positive features of functional weakness on examination include Hoover's sign, when there is weakness of hip extension which normalizes with contralateral hip flexion. [20] Signs of functional tremor include entrainment and distractibility. The patient with tremor should be asked to copy rhythmical movements with one hand or foot. If the tremor of the other hand entrains to the same rhythm, stops, or if the patient has trouble copying a simple movement this may indicate a functional tremor. Functional dystonia usually presents with an inverted ankle posture or clenched fist. [21] Positive features of dissociative or non-epileptic seizures include prolonged motionless unresponsiveness, long duration episodes (>2minutes) and symptoms of dissociation prior to the attack. These signs can be usefully discussed with patients when the diagnosis is being made. [22] [23] [24] [25]

Patients with functional movement disorders and limb weakness may experience symptom onset triggered by an episode of acute pain, a physical injury or physical trauma. They may also experience symptoms when faced with a psychological stressor, but this isn't the case for most patients. Patients with functional neurological disorders are more likely to have a history of another illness such as irritable bowel syndrome, chronic pelvic pain or fibromyalgia but this cannot be used to make a diagnosis. [26]

FND does not show up on blood tests or structural brain imaging such as MRI or CT scanning. However, this is also the case for many other neurological conditions so negative investigations should not be used alone to make the diagnosis. FND can occur alongside other neurological diseases and tests may show non-specific abnormalities which cause confusion for doctors and patients. [26]

DSM-5 diagnostic criteria

The Diagnostic and Statistical Manual of Mental Illness (DSM-5) lists the following diagnostic criteria for functional neurological symptoms (conversion disorder):

  1. One or more symptoms of altered voluntary motor or sensory function.
  2. Clinical findings can provide evidence of incompatibility between the symptom and recognized neurological or medical conditions.
  3. Another medical or mental disorder does not better explain the symptom or deficit.
  4. The symptom or deficit results in clinically significant distress or impairment in social, occupational, or other vital areas of functioning or warrants medical evaluation. [27]

The presence of symptoms defines an acute episode of functional neurologic disorder for less than six months, and persistent functional neurologic disorder includes the presence of symptoms for greater than six months. Functional neurologic disorder can also have the specifier of with or without the psychological stressor.

Associated conditions

Epidemiological studies and meta-analysis have shown higher rates of depression and anxiety in patients with FND compared to the general population, but rates are similar to patients with other neurological disorders such as epilepsy or Parkinson's disease. This is often the case because of years of misdiagnosis and accusations of malingering. [28] [29] [30] [31] Multiple sclerosis has some overlapping symptoms with FND, potentially a source of misdiagnosis. [32]

Prevalence

Dissociative (non-epileptic) seizures account for about 1 in 7 referrals to neurologists after an initial seizure, and functional weakness has a similar prevalence to multiple sclerosis. [33]

Treatment

Treatment requires a firm and transparent diagnosis based on positive features which both health professionals and patients can feel confident about. [17] It is essential that the health professional confirms that this is a common problem which is genuine, not imagined and not a diagnosis of exclusion. [34]

A multi-disciplinary approach to treating functional neurological disorder is recommended. Treatment options can include: [19]

Physiotherapy with someone who understands functional disorders may be the initial treatment of choice for patients with motor symptoms such as weakness, gait (walking) disorder and movement disorders. Nielsen et al. have reviewed the medical literature on physiotherapy for functional motor disorders up to 2012 and concluded that the available studies, although limited, mainly report positive results. [35]

For many patients with FND, accessing treatment can be difficult. Availability of expertise is limited and they may feel that they are being dismissed or told 'it's all in your head' especially if psychological input is part of the treatment plan. Some medical professionals are uncomfortable explaining and treating patients with functional symptoms. Changes in the diagnostic criteria, increasing evidence, literature about how to make the diagnosis and how to explain it and changes in medical training is slowly changing this. [36]

People with functional or dissociative seizures should try to identify warning signs and learn techniques to avoid harm or injury during and after the seizure. Be aware that relapses and flare-ups often recur, despite treatment.

Controversy

There was historically much controversy surrounding the FND diagnosis. Many 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 have argued that FND may merely be an unexplained somatic symptom disorder. [37] FND remains a stigmatized condition in the healthcare setting. [38] [39]

Related Research Articles

<span class="mw-page-title-main">Essential tremor</span> Movement disorder that causes involuntary tremors

Essential tremor (ET), also called benign tremor, familial tremor, and idiopathic tremor, is a medical condition characterized by involuntary rhythmic contractions and relaxations of certain muscle groups in one or more body parts of unknown cause. It is typically symmetrical, and affects the arms, hands, or fingers; but sometimes involves the head, vocal cords, or other body parts. Essential tremor is either an action (intention) tremor—it intensifies when one tries to use the affected muscles during voluntary movements such as eating and writing—or it is a postural tremor, which occurs when holding arms outstretched and against gravity. This means that it is distinct from a resting tremor, such as that caused by Parkinson's disease, which is not correlated with movement. Unlike Parkinson's disease, essential tremor may worsen with action.

<span class="mw-page-title-main">Tremor</span> Involuntary muscle contraction

A tremor is an involuntary, somewhat rhythmic muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, face, head, vocal folds, trunk, and legs. Most tremors occur in the hands. In some people, a tremor is a symptom of another neurological disorder.

A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term convulsion is often used as a synonym for seizure. However, not all epileptic seizures result in convulsions, and not all convulsions are caused by epileptic seizures. Non-epileptic convulsions have no relation with epilepsy, and are caused by non-epileptic seizures.

<span class="mw-page-title-main">Hysteria</span> Excess, ungovernable emotion

Hysteria is a term used to mean ungovernable emotional excess and can refer to a temporary state of mind or emotion. In the nineteenth century, female hysteria was considered a diagnosable physical illness in women. It is assumed that the basis for diagnosis operated under the belief that women are predisposed to mental and behavioral conditions; an interpretation of sex-related differences in stress responses. In the twentieth century, it shifted to being considered a mental illness. Many influential people such as Sigmund Freud and Jean-Martin Charcot dedicated research to hysteria patients.

Encephalopathy means any disorder or disease of the brain, especially chronic degenerative conditions. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of overall brain dysfunction; this syndrome has many possible organic and inorganic causes.

Conversion disorder (CD), or functional neurologic symptom disorder (FNsD), is a functional disorder that causes abnormal sensory experiences and movement problems during periods of high psychological stress. Individuals with CD present with highly distressing neurological symptoms such as numbness, blindness, paralysis, or convulsions, which are not consistent with a well-established organic cause and can be traced back to a psychological trigger.

<span class="mw-page-title-main">Aura (symptom)</span> Symptom of epilepsy and migraine

An aura is a perceptual disturbance experienced by some with epilepsy or migraine. An epileptic aura is actually a minor seizure.

Psychogenic non-epileptic seizures (PNES), also referred to as pseudoseizures, non-epileptic attack disorder (NEAD), functional seizures, or dissociative seizures, are episodes resembling an epileptic seizure but without the characteristic electrical discharges associated with epilepsy. PNES fall under the category of disorders known as functional neurological disorders (FND) and are typically treated by psychologists or psychiatrists.

Non-epileptic seizures (NES), also known as pseudoseizures, non-epileptic attack disorder (NEAD), functional seizures, or dissociative seizures, are paroxysmal events that appear similar to an epileptic seizure, but do not involve abnormal, rhythmic discharges of neurons in the brain. Symptoms may include shaking, loss of consciousness, and loss of bladder control.

<span class="mw-page-title-main">Monoplegia</span> Paralysis of a single limb

Monoplegia is paralysis of a single limb, usually an arm. Common symptoms associated with monoplegic patients are weakness, numbness, and pain in the affected limb. Monoplegia is a type of paralysis that falls under hemiplegia. While hemiplegia is paralysis of half of the body, monoplegia is localized to a single limb or to a specific region of the body. Monoplegia of the upper limb is sometimes referred to as brachial monoplegia, and that of the lower limb is called crural monoplegia. Monoplegia in the lower extremities is not as common of an occurrence as in the upper extremities. Monoparesis is a similar, but less severe, condition because one limb is very weak, not paralyzed. For more information, see paresis.

<span class="mw-page-title-main">Primary polydipsia</span> Medical condition

Primary polydipsia and psychogenic polydipsia are forms of polydipsia characterised by excessive fluid intake in the absence of physiological stimuli to drink. Psychogenic polydipsia caused by psychiatric disorders—oftentimes schizophrenia—is frequently accompanied by the sensation of dry mouth. Some conditions with polydipsia as a symptom are non-psychogenic. Primary polydipsia is a diagnosis of exclusion.

Dissociative amnesia or psychogenic amnesia is a dissociative disorder "characterized by retrospectively reported memory gaps. These gaps involve an inability to recall personal information, usually of a traumatic or stressful nature." The concept is scientifically controversial and remains disputed.

Myoclonic epilepsy refers to a family of epilepsies that present with myoclonus. When myoclonic jerks are occasionally associated with abnormal brain wave activity, it can be categorized as myoclonic seizure. If the abnormal brain wave activity is persistent and results from ongoing seizures, then a diagnosis of myoclonic epilepsy may be considered.

A functional symptom is a medical symptom with no known physical cause. In other words, there is no structural or pathologically defined disease to explain the symptom. The use of the term 'functional symptom' does not assume psychogenesis, only that the body is not functioning as expected. Functional symptoms are increasingly viewed within a framework in which 'biological, psychological, interpersonal and healthcare factors' should all be considered to be relevant for determining the aetiology and treatment plans.

Spasmodic dysphonia, also known as laryngeal dystonia, is a disorder in which the muscles that generate a person's voice go into periods of spasm. This results in breaks or interruptions in the voice, often every few sentences, which can make a person difficult to understand. The person's voice may also sound strained or they may be nearly unable to speak. Onset is often gradual and the condition is lifelong.

Classified as a "conversion disorder" by the DSM-IV, a psychogenic disease is a condition in which mental stressors cause physical symptoms matching other disorders. The manifestation of physical symptoms without biologically identifiable cause results from disruptions in normal brain function due to psychological stress. During a psychogenic episode, neuroimaging has shown that neural circuits affecting functions such as emotion, executive functioning, perception, movement, and volition are inhibited. These disruptions become strong enough to prevent the brain from voluntarily allowing certain actions. When the brain is unable to signal to the body to perform an action voluntarily, physical symptoms of a disorder arise. Examples of diseases that are deemed to be psychogenic in origin include psychogenic seizures, psychogenic polydipsia, psychogenic tremor, and psychogenic pain.

<span class="mw-page-title-main">Neurological disorder</span> Any disorder of the nervous system

A neurological disorder is any disorder of the nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord or other nerves can result in a range of symptoms. Examples of symptoms include paralysis, muscle weakness, poor coordination, loss of sensation, seizures, confusion, pain, tauopathies, and altered levels of consciousness. There are many recognized neurological disorders, some are relatively common, but many are rare.

<span class="mw-page-title-main">Blocq's disease</span> Loss of memory of specialized movements causing the inability to maintain an upright posture

Blocq's disease was first considered by Paul Blocq (1860–1896), who described this phenomenon as the loss of memory of specialized movements causing the inability to maintain an upright posture, despite normal function of the legs in the bed. The patient is able to stand up, but as soon as the feet are on the ground, the patient cannot hold himself upright nor walk; however when lying down, the subject conserved the integrity of muscular force and the precision of movements of the lower limbs. The motivation of this study came when a fellow student Georges Marinesco (1864) and Paul published a case of parkinsonian tremor (1893) due to a tumor located in the substantia nigra.

Functional disorders are a group of recognisable medical conditions which are due to changes to the functioning of the systems of the body rather than due to a disease affecting the structure of the body.

Somatic symptom disorder, also known as somatoform disorder, or somatization disorder, is defined by one or more chronic physical symptoms that coincide with excessive and maladaptive thoughts, emotions, and behaviors connected to those symptoms. The symptoms are not deliberately produced or feigned, and they may or may not coexist with a known medical ailment.

References

  1. ↑ Stone J, Sharpe M, Rothwell PM, Warlow CP (May 2003). "The 12 year prognosis of unilateral functional weakness and sensory disturbance". Journal of Neurology, Neurosurgery, and Psychiatry. 74 (5): 591–596. doi:10.1136/jnnp.74.5.591. PMC   1738446 . PMID   12700300.
  2. ↑ Aybek S, Perez DL (January 2022). "Diagnosis and management of functional neurological disorder". BMJ. 376: o64. doi:10.1136/bmj.o64. PMID   35074803. S2CID   246210869.
  3. ↑ Carey, Katie; Watson, Meagan (2003). Reset & Rewire: The FND Workbook for Kids & Teens. Houston, TX: Illustrated Nurse Press. p. 4. ISBN   9798218232047.
  4. ↑ Lehn A, Gelauff J, Hoeritzauer I, Ludwig L, McWhirter L, Williams S, et al. (March 2016). "Functional neurological disorders: mechanisms and treatment". Journal of Neurology. 263 (3): 611–620. doi:10.1007/s00415-015-7893-2. PMID   26410744. S2CID   23921058.
  5. ↑ Goldstein LH, Robinson EJ, Chalder T, Reuber M, Medford N, Stone J, et al. (March 2022). "Six-month outcomes of the CODES randomised controlled trial of cognitive behavioural therapy for dissociative seizures: A secondary analysis". Seizure. 96: 128–136. doi:10.1016/j.seizure.2022.01.016. PMC   8970049 . PMID   35228117.
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  26. 1 2 Stone J, Smyth R, Carson A, Lewis S, Prescott R, Warlow C, Sharpe M (October 2005). "Systematic review of misdiagnosis of conversion symptoms and "hysteria"". BMJ. 331 (7523): 989. doi: 10.1136/bmj.38628.466898.55 . PMC   1273448 . PMID   16223792.
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  32. ↑ Walzl D, Solomon AJ, Stone J (February 2022). "Functional neurological disorder and multiple sclerosis: a systematic review of misdiagnosis and clinical overlap". Journal of Neurology. 269 (2): 654–663. doi:10.1007/s00415-021-10436-6. PMC   8782816 . PMID   33611631.
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