Conversion disorder

Conversion disorder (CD) was a formerly diagnosed psychiatric disorder characterized by abnormal sensory experiences and movement problems during periods of high psychological stress. Individuals diagnosed with CD presented with highly distressing neurological symptoms such as numbness, blindness, paralysis, or convulsions, none of which were consistent with a well-established organic cause and could be traced back to a psychological trigger. CD is no longer a diagnosis in the WHO's ICD-11 or APA's DSM-5 and was superseded by functional neurologic disorder (FND), a similar diagnosis that notably removed the requirement for a psychological stressor to be present.

It was thought that these symptoms arise in response to stressful situations affecting a patient's mental health. Individuals diagnosed with conversion disorder have a greater chance of experiencing certain psychiatric disorders including anxiety disorders, mood disorders, and personality disorders compared to those diagnosed with neurological disorders.

Conversion disorder was partly retained in the DSM-5-TR and ICD-11, but was renamed to functional neurological symptom disorder (FNSD) and dissociative neurological symptom disorder (DNSD), respectively. FNSD covers a similar range of symptoms found in conversion disorder, but does not include the requirements for a psychological stressor to be present. The new criteria no longer require feigning to be disproven before diagnosing FNSD. A fifth criterion describing a limitation in sexual functioning that was included in the DSM-IV was removed in the DSM-5 as well. The ICD-11 classifies DNSD as a dissociative disorder with unspecified neurological symptoms.

Signs and symptoms

Conversion disorder presented with symptoms following exposure to a certain stressor, typically associated with trauma or psychological distress. Usually, the physical symptoms of the disorder affect the senses or movement. Common symptoms included blindness, partial or total paralysis, inability to speak, deafness, numbness, difficulty swallowing, incontinence, balance problems, non-epileptic seizures, tremors, and difficulty walking. Feelings of breathlessness were said to have possibly indicated conversion disorder or sleep paralysis. Symptoms of conversion disorder usually occur suddenly. Conversion disorder was typically observed in people ages 10 to 35, affecting between 0.011% and 0.5% of the general population.

Conversion disorder presented motor or sensory symptoms including:

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 (dysphagia) 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, double vision
Impaired hearing
Loss or disturbance of touch or pain sensation

Conversion symptoms typically do not conform to known anatomical pathways and physiological mechanisms. It 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.

Sexual dysfunction and pain were also considered symptoms of conversion disorder, but if a patient only has these symptoms, they should be diagnosed with sexual pain disorder or pain disorder.

Diagnosis

Definition

Conversion disorder is now partly contained under functional neurological symptom disorder (FNSD). In cases of conversion disorder, there is a psychological stressor.

The diagnostic criteria for functional neurologic symptom disorder, as set out in DSM-5, are:

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 amnesia or memory loss
With special sensory loss symptoms (e.g. visual blindness, olfactory loss, or hearing disturbance)
With mixed symptoms.

Specify if:

Acute episode: symptoms present for less than six months
Persistent: symptoms present for six months or more.

Specify if:

Psychological stressor (conversion disorder)
No psychological stressor (functional neurologic symptom disorder)

Exclusion of neurological disease

Conversion disorder presents with symptoms that typically resemble a neurological disorder such as stroke, multiple sclerosis, epilepsy, hypokalemic periodic paralysis, or narcolepsy. 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 (i.e., certain aspects of the presentation that were thought to be rare in neurological disease but common in conversion disorder). The validity of many of these signs has been questioned by a study showing that they also occur 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 2006 study, no evidence was found that patients with functional symptoms are any more likely to exhibit this than patients with a confirmed organic disease. In the DSM-5, la belle indifférence was removed as a diagnostic criterion.

Another feature thought to be important was that symptoms tended to be more severe on the non-dominant, usually left side of the body. There have been a number of theories about this, such as the relative involvement of cerebral hemispheres in emotional processing, or more simply, 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. A 2005 meta-analysis has shown that misdiagnosis rates since that paper was published are around four percent, the same as for other neurological diseases.

Treatment

Treatments for conversion disorder included hypnosis, psychotherapy, physical therapy, and stress management. Treatment plans will consider duration and presentation of symptoms and may include one or multiple of the above treatments. This may include the following:

Occupational therapy to maintain autonomy in activities of daily living.
Treatment of comorbid depression or anxiety if present.
Educating patients on the causes of their symptoms might help them learn to manage both the psychiatric and physical aspects of their condition. Psychological counseling is often warranted given the known relationship between conversion disorder and emotional trauma. This approach ideally takes place alongside other types of treatment.
Medications such as serotonin–norepinephrine reuptake inhibitors (SNRIs), a class of antidepressants, and sedatives such as benzodiazepines may help reduce stress and also relieve or prevent symptoms from occurring.

There is little evidence-based treatment of conversion disorder. Other treatments such as cognitive behavioral therapy (CBT), hypnosis, EMDR, psychodynamic psychotherapy, transcranial magnetic stimulation (TMS), virtual reality therapy, and EEG brain biofeedback need further trials. Psychoanalytic treatment may possibly be helpful. Most studies assessing the efficacy of these treatments are of poor quality and larger, better controlled studies are urgently needed. CBT is the most common treatment, with a 13% improvement rate.

Prognosis

Empirical studies have found that the prognosis for conversion disorder varies widely, with some cases resolving in weeks, and others enduring for years or decades. Although patients may go into remission, they can relapse at any point.

Epidemiology

Frequency

Information on the frequency of conversion disorder 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 disorder typically required 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 the disorder. In 1976, large scale psychiatric registers in the U.S. and Iceland found incidence rates of 22 and 11 newly diagnosed cases per 100,000 person-years, respectively. In 2002, some estimates claim that in the general population, between 0.011% and 0.5% of the population have conversion disorder. A 2007 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 people may know less about medical and psychological concepts.

Gender

In recent surveys of conversion disorder, females predominate, with between two and six female patients for every male. Some research suggests however that this gender disparity may be confounded by higher rates of violence against women.

Age

Conversion disorder may present at any age, but is rare in children younger than ten or in the elderly. Studies suggest a peak onset in the mid-to-late 30s.

In Greek mythology, hysteria, a similarly described condition, 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 causes complications in the uterus. Many Greeks believed 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, causing it to move in the body. Therefore, he argued, all women should be married and enjoy a satisfactory sexual life.

From the 13th century, women with hysteria were exorcised, as it was believed that they were possessed by the devil. It was believed that if doctors could not find the cause of a disease or illness, it must be caused by the devil.

Sigmund Freud referred to the condition as both hysteria and conversion disorder throughout his career. He believed 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 have the disorder. suggested the emotional charge deriving from painful experiences would be consciously repressed as a way of managing the pain, but that the emotional charge would be somehow "converted" into 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".

Pierre Janet, a highly noted psychologist during the early 20th century, 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.

Some support for the Freudian model comes from findings of high rates of childhood sexual abuse in conversion patients. Support for the dissociation model comes from studies showing heightened suggestibility in patients with conversion disorder. Critics argue that it can be challenging to find organic pathologies for all symptoms, and so the practice of diagnosing patients with such symptoms as having hysteria led to the disorder being meaningless, vague and a sham diagnosis, as it does not refer to any definable disease.

Throughout its history, many patients have been misdiagnosed with hysteria or conversion disorder when they had organic disorders such as tumors, epilepsy, or vascular diseases. This has led to patient deaths, a lack of appropriate care, and suffering for the patients.