Functional neurological symptom disorder
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Functional neurological disorder (FND) is a condition in which patients experience neurological symptoms such as weakness, movement disorders, sensory symptoms and blackouts. The brain of a patient with functional neurological symptom disorder is structurally normal, but functions incorrectly. According to consensus from the literature and from physicians and psychologists practicing in the field, "functional symptoms, also called "medically unexplained," "psychogenic," or "hysterical," are symptoms that are clinically recognisable as not being caused by a definable organic disease". Other terms for functional neurological disorder include functional neurological symptom disorder, conversion disorder, and psychogenic movement disorder/non-epileptic seizures. Functional neurological disorders are common in neurological services, accounting for up to one third of outpatient neurology clinic attendances, and associated with as much physical disability and distress as other neurological disorders. The diagnosis is made based on positive signs and symptoms in the history and examination during consultation of a neurologist (see below). 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 dissociative (non-epileptic) attacks.
Signs and symptoms
There are a great number of symptoms experienced by those with functional neurological disorder. It is important to note that the symptoms experienced by those with FND feel subjectively very real to the patient, and may be associated with debility. At the same time, the origin of symptoms is complex since it can be associated with psychiatric disturbance and secondary gain including litigation, disability status, family conflicts and other factors. The core symptoms are those of motor or sensory function or episodes of altered awareness
- Limb weakness or paralysis
- Blackouts (also called dissociative or non-epileptic seizures/attacks) – these may look like epileptic seizures or faints
- Movement disorders including tremors, dystonia (spasms), myoclonus (jerky movements)
- Visual symptoms including loss of vision or double vision
- Speech symptoms including dysphonia (whispering speech), slurred or stuttering speech
- Sensory disturbance including hemisensory syndrome (altered sensation down one side of the body)
Epidemiology and aetiology
Functional neurological disorders are a common problem, and are the second most common reason for a neurological outpatient visit after headache/migraine. 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.
Aetiology and mechanism
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.
A diagnosis of a functional neurological disorder is dependent on positive features from the history and examination.
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. 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. 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, however, occur alongside other neurological diseases and tests may show non-specific abnormalities which cause confusion for doctors and patients.
ICD-11 diagnostic criteria
The International Classification of Disease (ICD-11) which is due to be finalised in 2017 will have functional disorders within the neurology section for the first time.
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.
Historically, misdiagnosis rates have been high due to the complex nature of the disorder although some research is now indicates that misdiagnosis may be reducing.
Treatment requires a firm and transparent diagnosis based on positive features which both health professionals and patients can feel confident about. 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.
Confidence in the diagnosis does not improve symptoms, but appears to improve the efficacy of treatments such as physiotherapy which require altering established abnormal patterns of movement.
A multi-disciplinary approach to treating functional neurological disorder is recommended. Treatment options can include:
- Physiotherapy and occupational therapy
- Medication such as sleeping tablets, painkillers, anti-epileptic medications and anti-depressants
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. Since then several studies have shown positive outcomes. In one study, up to 65% of patients were very much or much improved after five days of intensive physiotherapy even though 55% of patients were thought to have poor prognosis. In a randomised controlled trial of physiotherapy there was significant improvement in mobility which was sustained on one year follow up. In multidisciplinary settings 69% of patients markedly improved even with short rehabilitation programmes. Benefit from treatment continued even when patients were contacted up 25months after treatment.
For patients with severe and chronic FND a combination of physiotherapy, occupational therapy and cognitive behavioural therapy may be the best combination with positive studies being published in patients who have had symptoms for up to three years before treatment.
Cognitive behavioural therapy (CBT) alone may be beneficial in treating patients with dissociative (non-epileptic) seizures. A randomised controlled trial of patients who undertook 12 sessions of CBT which taught patients how to interrupt warning signs before seizure onset, challenged unhelpful thoughts and helped patients start activities they had been avoiding found a reduction in the seizure frequency with positive outcomes sustained at six month follow up. A large multicentre trial of CBT for dissociative (non-epileptic) seizures started in 2015 in the UK.
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
After a diagnosis of functional neurological disorder has been made, it is important that the neurologist explains the illness fully to the patient to ensure the patient understands the diagnosis.
Some, but not all patients with FND may experience low moods or anxiety due to their condition. However, they will often not seek treatment due being worried that a doctor will blame their symptoms on their anxiety or depression.
It is recommended that the treatment of functional neurological disorder should be balanced and involve a whole-person approach. This means that it should include professionals from multiple departments, including neurologists, general practitioners (or primary health care providers), physiotherapists, occupational therapists. At the same time, ruling out secondary gain, malingering, conversion disorder and other factors, including the time and financial resources involved in assessing and treating patients who demand hospital resources but would be better served in psychological settings, must all be balanced.
Functional neurological symptom disorder can mimic many other conditions. Some alternative diagnoses for FND include:
- Hemiplegic migraine
- Multiple sclerosis
- Motor neurone disease
- Autoimmune disorders
- Ehlers–Danlos syndrome
- Vitamin B12 deficiency or pernicious anaemia
- Myasthenia gravis
The first evidence of FND dates back to 1900 BC, where the symptoms were blamed on the uterus moving within the female body. The treatment varied "depending on the position of the uterus, which must be forced to return to its natural position. If the uterus had moved upwards, this could be done by placing malodorous and acrid substances near the woman's mouth and nostrils, while scented ones were placed near her vagina; on the contrary, if the uterus had lowered, the document recommends placing the acrid substances near her vagina and the perfumed ones near her mouth and nostrils."
In Greek mythology, hysteria, the original name for FND, was thought to be caused by a lack of orgasms, uterine melancholy and not procreating. Plato, Aristotle and Hippocrates believed that a lack of sex upset the uterus. The Greeks believed that it could be prevented and cured with wine and orgies. Hippocrates argued that a lack of regular sexual intercourse led to the uterus producing toxic fumes and caused it to move in the body, and that this meant that all women should be married and enjoy a satisfactory sexual life.
Throughout the Middle Ages, melissa, a natural remedy, was used to treat hysteria. Women with the condition were seen as the cause of the condition, which was then referred to as amor heroycus, or the madness of love, unfulfilled sexual desire. Trotula de Ruggerio, the first female doctor in Europe, believed that abstinence caused illness, and advised women to take remedies such as mint or musk oil.
From the 13th century, women with hysteria were exorcised, as it was believed that they were possessed by the devil. They believed that if doctors could not find the cause of a disease or illness, it must be caused by the devil.
In the beginning of the 16th century, women were sexually stimulated by midwives in order to relieve their symptoms. Girolamo Cardano and Giovanni Battista Della Porta believed that polluted water and fumes caused the symptoms of hysteria. Towards the end of the century, however, 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 hysteria may have an organic cause. He also proved that the uterus is not the cause of symptoms.
In 1692, in Salem (MA), there was an outbreak of hysteria. This led to the Salem witch trials, where the 'witches' had symptoms such as sudden movements, staring eyes and uncontrollable jumping.
From the 18th century, there is a move from the idea of hysteria being caused by the uterus to it being caused by the nervous system. 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 18th century, the illness was confirmed as being a neurological disorder but a small number of doctors still believed in the previous form hysteria. However, as early as 1874, doctors including W. B. Carpenter and J. A. Omerod began to speak out against hysteria due to there being no evidence of its existence.
Freud referred to the condition as hysteria. However, throughout his career, Freud admitted that "he had not succeeded in curing a single patient, and there was no clinical evidence that his theory had any merit whatsoever". Freud frequently made serious diagnostic errors due to his theory of hysteria. In 1901, a patient died of a sarcoma of the abdominal glands, which had given her abdominal pain. One key feature of hysteria was said to be abdominal pain, and so Freud treated her for this, and claimed her condition had "cleared up". After her death, he then claimed that hysteria had caused her tumour; however, there is no evidence to support his claim.
Today, there is growing evidence that psychological stress does not cause FND. A recent study by the charity FNDHope found that psychological triggers affected only 30% of patients. Doctors are moving on to look at the role of the central nervous system in FND symptoms.
Research is ongoing in many aspects of functional neurological disorders but large studies are needed to definitely answer key questions including: What is the best treatment for patients with FND? Even disorders like multiple sclerosis and Parkinson's disease have no definite known cause. The importance of increased awareness in the medical world of what constitutes a positive diagnosis of FND and what the best treatments are may, in the short term, be where research is focused.
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Online resources include:
- Neurosymptoms is written by Dr Jon Stone a Scottish neurologist.
- FND Hope is registered charity in the United States and non-profit organization in the United Kingdom. They collaborate with Dr. Jon Stone and Dr. Mark Edwards.
- FND Dimensions is a registered charity in England and Wales who aim "to develop a network of 'peer support groups' across the UK either in face to face meetings or online via methods such as Skype".
- FiNDME is a UK based non profit organisation for patients and carers with FND and ME.
- #functionalneurologicaldisorder on Instagram has a small community of patients.
- FND Support is an Instagram profile dedicated to FND.
- FND Action is a registered charity in England and Wales providing support and information for people with FND.
- FND Awareness Day is held on April 13th.