|Classification and external resources|
Conversion disorder is a diagnostic category used in some psychiatric classification systems. It is sometimes applied to patients who present with neurological symptoms, such as numbness, blindness, paralysis, or fits, which are not consistent with a well-established organic cause, and which cause significant distress. It is thought that these symptoms arise in response to stressful situations affecting a patient's mental health. Conversion disorder is considered a psychiatric disorder in the Diagnostic and Statistical Manual of Mental Disorders fifth edition (DSM-5).
Formerly known as "hysteria", the concept of conversion disorder came to prominence at the end of the 19th century, when the neurologists Jean-Martin Charcot, Sigmund Freud and psychologist Pierre Janet focused their studies on the subject. Before their studies, people with hysteria were often believed to be malingering. The term "conversion" has its origins in Freud's doctrine that anxiety is "converted" into physical symptoms. Though previously thought to have vanished from the west in the 20th century, some research has suggested it is as common as ever.
In the DSM-V, Conversion Disorder was put under the heading of 'Functional Neurological Symptom Disorder', alongside the similar condition of Functional Neurological Disorder (FND), which can have identical symptoms but exists with no psychological stressor. Some doctors believe FND to be caused by an issue with the Central Nervous System, however due to limited research, FND remains in the DSM.
The diagnostic criteria for Conversion Disorder, as set out in the DSM-V are:
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.
The tenth revision of the World Health Organization's International Classification of Diseases uses the term "conversion" as an alternative descriptor for the dissociative disorders class of mental and behavioural disorders (i.e. the F44 class), with the explicit suggestion that dissociative and conversion symptoms probably share common psychological mechanisms. In ICD-10, the dissociative [conversion] disorders class includes 10 disorders that, in addition to specific criteria for each individual disorder, must each meet the following general criteria:
- No evidence of a physical disorder that can explain the symptoms that characterize the disorder (but physical disorders may be present that give rise to other symptoms);
- Convincing associations in time between the symptoms of the disorder and stressful events, problems or needs.
Signs and symptoms
In some cases, conversion disorder begins with some stressor, trauma, or psychological distress. Usually the physical symptoms of the syndrome affect the senses or movement. Common symptoms include blindness, partial or total paralysis, inability to speak, deafness, numbness, sores, difficulty swallowing, incontinence, balance problems, seizures, tremors, and difficulty walking. These symptoms are attributed to conversion syndrome when a medical explanation for the afflictions cannot be found. Symptoms of conversion disorder usually occur suddenly. Conversion disorder is typically seen in individuals 10 to 35 years old.
Conversion disorder can present with motor or sensory symptoms including any of the following:
Motor symptoms or deficits:
- Impaired coordination or balance
- Weakness/paralysis of a limb or the entire body (hysterical paralysis or motor conversion disorders)
- Impairment or loss of speech (hysterical aphonia)
- Difficulty swallowing or a sensation of a lump in the throat
- Urinary retention
- Psychogenic non-epileptic seizures or convulsions
- Persistent dystonia
- Tremor, myoclonus or other movement disorders
- Gait problems (astasia-abasia)
- Loss of consciousness (fainting)
Sensory symptoms or deficits:
- Impaired vision (hysterical blindness), double vision
- Impaired hearing (deafness)
- Loss or disturbance of touch or pain sensation
Conversion symptoms typically do not conform to known anatomical pathways and physiological mechanisms. It has has sometimes been stated that the presenting symptoms tend to reflect the patient's own understanding of anatomy and that the less medical knowledge a person has, the more implausible are the presenting symptoms. However, no systematic studies have yet been performed to substantiate this statement.
The original Freudian model suggested that the emotional charge of painful experiences would be consciously repressed as a way of managing the pain, but this emotional charge would be somehow "converted" into the neurological symptoms. Freud later argued that the repressed experiences were of a sexual nature. As Peter Halligan comments, conversion has 'the doubtful distinction among psychiatric diagnoses of still invoking Freudian mechanisms'.
Janet, the other great theoretician of hysteria, argued that symptoms arose through the power of suggestion, acting on a personality vulnerable to dissociation. In this hypothetical process, the subject's experience of their leg, for example, is split-off from the rest of their consciousness, resulting in paralysis or numbness in that leg. Later authors have attempted to combine elements of these models, but none of them has a firm empirical basis.
Some support for the Freudian model comes from findings of high rates of childhood sexual abuse in conversion patients and from a recent neuroimaging study showing abnormal emotion processing of a traumatic event linked to motor processing of the affected limb, in a patient with conversion. Support for the dissociation model comes from studies showing heightened suggestibility in conversion patients, and in abnormalities in motor imagery.
Much recent work has been done to identify the underlying causes of the conversion and related disorders as well as to better understand why conversion and hysteria appear more commonly in women. Current theoreticians tend to believe that there is no single cause for these disorders. Instead, the emphasis tends to be on the individual understanding of the patient as well as on a variety of therapeutic techniques. While the exact causes of conversion disorder are unknown, symptoms of the disorder seem to relate to the occurrence of a psychological conflict or stressor. In some cases, the onset of the disorder correlates to a traumatic or stressful event, There are also certain populations that are considered at risk for conversion disorder including people suffering from a medical illness or condition, people with personality disorder, and individuals with dissociative identity disorder.
There has been much recent interest in functional neuroimaging in conversion. As researchers identify the mechanisms which underlie conversion symptoms it is hoped these will allow the development of a neuropsychological model. A number of such studies have been performed, including some which suggest that blood flow in patients' brains may be abnormal while they are unwell. These have all been too small to be confident of the generalisability of their findings, however, so no neuropsychological model has been clearly established.
A 2007 review found that conversion disorder and dissociative disorders are statistically associated, share features such as a history of abuse and high suggestibility, and likely have common underlying causes.
An evolutionary psychology explanation for conversion disorder is that the symptom may have been evolutionarily advantageous during warfare. A non-combatant with these symptoms signals non-verbally, possibly to someone speaking a different language, that she or he is not dangerous as a combatant and also may be carrying some form of dangerous infectious disease. This can explain that conversion disorder may develop following a threatening situation, that there may be a group effect with many people simultaneously developing similar symptoms (as in mass psychogenic illness), and the gender difference in prevalence.
The Lacanian model accepts conversion as common phenomenon inherent in specific psychical structure. The higher prevalence of it among women is based on somewhat different intrapsychic relation to the body compared to that of typical males. This allows the formation of conversion symptoms.
Exclusion of neurological disease
Conversion disorder presents with symptoms that typically resemble a neurological disorder such as stroke, multiple sclerosis, epilepsy or hypokalemic periodic paralysis. The neurologist must carefully exclude neurological disease, through examination and appropriate investigations. However, it is not uncommon for patients with neurological disease to also have conversion disorder.
In excluding neurological disease, the neurologist has traditionally relied partly on the presence of positive signs of conversion disorder — certain aspects of the presentation that were thought to be rare in neurological disease, but common in conversion. The validity of many of these signs has been questioned, however, by a study showing that they also occurred in neurological disease. One such symptom, for example, is La belle indifférence, described in DSM-IV as "a relative lack of concern about the nature or implications of the symptoms". In a later study no evidence was found that patients with "functional" symptoms are any more likely to exhibit this than patients with a confirmed organic disease.
Another feature thought to be important was that symptoms would tend to be more severe on the non-dominant (usually left) side; there were a variety of theories such as the relative involvement of cerebral hemispheres in emotional processing, or more simply just that it was "easier" to live with a functional deficit on the non-dominant side. However, a literature review of 121 studies established that this was not true, with publication bias the most likely explanation for this commonly held view. Although agitation is often assumed to be a positive sign of conversion disorder, release of epinephrine is a well-demonstrated cause of paralysis from hypokalemic periodic paralysis.
Misdiagnosis does sometimes occur. In a highly influential study from the 1960s, Eliot Slater demonstrated that misdiagnoses had occurred in one third of his 112 patients with conversion disorder. Later authors have argued that the paper was flawed, however, and a meta-analysis has shown that misdiagnosis rates since that paper are around 4%, the same as for other neurological diseases.
Exclusion of feigning
Conversion disorder is unique in DSM-5 in explicitly requiring the exclusion of deliberate feigning. Unfortunately, this is only likely to be demonstrable where the patient confesses, or is "caught out" in a broader deception, such as a false identity. One neuroimaging study suggested that feigning may be distinguished from conversion by the pattern of frontal lobe activation; however, this is a piece of research, rather than a clinical technique. True rates of feigning in medicine remain unknown, though neurological presentations of feigning may be among the more common.
The psychological mechanism can be the most difficult aspect of the conversion diagnosis. Not all classification schemes require the identification of a psychological stressor or antecedent, and indeed these are not always identifiable. Even if there is a clear antecedent trauma or other possible psychological trigger, it is still not clear exactly how this gives rise to the symptoms observed.
There are a number of different treatments that are available to treat and manage conversion syndrome. Treatments for conversion syndrome include hypnosis, psychotherapy, physical therapy, stress management, and transcranial magnetic stimulation. Treatment plans will consider duration and presentation of symptoms and may include one or multiple of the above treatments. This may include the following:
- Explanation. This must be clear and coherent as attributing physical symptoms to a psychological cause is not accepted by many educated people in western cultures. It must emphasize the genuineness of the condition, that it is common, potentially reversible and does not mean that the sufferer is psychotic. Taking an etiologically neutral stance by describing the symptoms as functional may be helpful but further studies are required. Ideally, the patient should be followed up neurologically for a while to ensure that the diagnosis has been understood.
- Physiotherapy where appropriate;
- Occupational Therapy to maintain autonomy in activities of daily living;
- Treatment of comorbid depression or anxiety if present.
There is little evidence-based treatment of conversion disorder. Other treatments such as cognitive behavioral therapy, hypnosis, EMDR, and psychodynamic psychotherapy, EEG brain biofeedback need further trials. Psychoanalytic treatment may possibly be helpful. However, most studies assessing the efficacy of these treatments are of poor quality and larger, better controlled studies are urgently needed.
Information on the frequency of conversion disorder in the West is limited, in part due to the complexities of the diagnostic process. In neurology clinics, the reported prevalence of unexplained symptoms among new patients is very high (between 30 and 60%) However, diagnosis of conversion typically requires an additional psychiatric evaluation, and since few patients will see a psychiatrist it is unclear what proportion of the unexplained symptoms are actually due to conversion. Large scale psychiatric registers in the US and Iceland found incidence rates of 22 and 11 newly diagnosed cases per 100,000 person-years, respectively,
Although it is often thought that the frequency of conversion may be higher outside of the West, perhaps in relation to cultural and medical attitudes, evidence of this is limited. A community survey of urban Turkey found a prevalence of 5.6%. Many authors have found occurrence of conversion to be more frequent in rural, lower socio-economic groups, where technological investigation of patients is limited and individuals may be less knowledgeable about medical and psychological concepts.
Historically, the concept of 'hysteria' was originally understood to be a condition exclusively affecting women, though the concept was eventually extended to men. In recent surveys of conversion disorder (formerly classified as "hysterical neurosis, conversion type"), females predominate, with between 2 and 6 female patients for every male.
Conversion disorder has been described as early as the time of Hippocrates.
In the 19th century, physicians such as Silas Weir Mitchell in the US and Paul Briquet and Jean-Martin Charcot in France developed ideas about patients sharing unexplained neurological symptoms. Charcot specialised in treating patients who were suffering from a variety of unexplained physical symptoms including paralysis, contractures (muscles which contract and cannot be relaxed) and seizures. Some of these patients sporadically and compulsively adopted a bizarre posture (christened arc-de-cercle) in which they arched their body backwards until they were supported only by their head and their heels.
The term "conversion disorder" originated with Freud. He viewed these apparently neurological symptoms as a result of the conversion of intrapsychic distress into physical symptoms. This distress was thought to cause the brain to unconsciously disable or impair a bodily function as a side effect of the original repression, which served to relieve the patient's anxiety. However, some have claimed that patients do remain distressed by their symptoms in the long term
It has also been suggested that at least some of the classic psychoanalytic cases of hysteria, such as "Anna O.", may actually have suffered from organic illness. In fact, in Studies On Hysteria in which Breuer's Anna O. case was first presented, Freud wrote this: "Others of the patient's symptoms were not of a hysterical nature at all. This is true, for example, of the neck cramps, which I consider a modified version of migraine and which as such are not to be classified as a neurosis but as an organic disorder. Hysterical symptoms, however, regularly become attached to these." Freud believed that all hysterical symptoms ultimately have some organic components.
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