Conversion Disorder in Emergency Medicine 

Conversion disorder is classified as one of the somatoform disorders in the Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association, Fourth Edition, Text Revision (DSM-IV-TR).^[1] Although defined as a condition that presents as an alteration or loss of a physical function suggestive of a physical disorder, conversion disorder is presumed to be the expression of an underlying psychological conflict or need.

The critical psychological conflict or stress may not be apparent initially, but it becomes evident in the course of obtaining a patient’s history: ideally, it is a psychological factor related symbolically and temporally to symptom onset. Conversion symptoms are presumed to result from an unconscious process. (Conscious/intentional production of physical symptoms is classified as factitious disorder or malingering.) Conversion symptoms are not considered to be under voluntary control, and, should not be explained by any physical disorder or known pathological mechanism (after appropriate medical evaluation).

Though classified with somatoform disorders including hypochondriasis and body dysmorphic disorder in DSM-III and DSM-IV, conversion disorder is classified as a dissociative disorder in ICD-10, keeping its long association with hysteria (Dissociative Disorders in DSM-IV).^{[2, 3]} Clinical descriptions of conversion disorder date to almost 4000 years ago; the Egyptians attributed symptoms to a "wandering uterus." In the 19th century, Paul Briquet described the disorder as a dysfunction of the CNS.^{[4, 5]} Freud first used the term conversion to refer to the development of a somatic symptom to help bind anxiety around a repressed conflict.^[6]

For related information, see Medscape's Psychiatry and Mental Health Specialty page.

Presenting symptoms can range far across the field of clinical neurology. Conversion reactions usually approximate lesions in the nervous system’s voluntary motor or sensory pathways. Symptoms most commonly reported are weakness, paralysis, pseudoseizures, involuntary movements (eg, tremors), and sensory disturbances. These losses or distortions of neurologic function cannot adequately be accounted for by organic disease. Functional MRI (fMRI) and transcranial magnetic stimulation (TMS) studies have shown different activation patterns in patients with conversion symptoms and healthy control subjects; this is in keeping with the "involuntary" nature of conversion symptoms.^{[7, 8]} Patient's whose symptoms are limited to pain or sexual functioning are not classified under conversion disorder; likewise, patients already classified as demonstrating somatization disorder or schizophrenia are also not classified under conversion disorder.

Diagnostic criteria for conversion disorder as defined in the DSM-IV are as follows:^[1]

• One or more symptoms or deficits are present that affect voluntary motor or sensory function that suggest a neurologic or other general medical condition.
• Psychologic factors are judged to be associated with the symptom or deficit because conflicts or other stressors precede the initiation or exacerbation of the symptom or deficit.
• The symptom or deficit is not intentionally produced or feigned (as in factitious disorder or malingering).
• The symptom or deficit, after appropriate investigation, cannot be explained fully by a general medical condition, the direct effects of a substance, or as a culturally sanctioned behavior or experience.
• The symptom or deficit causes clinically significant distress or impairment in social, occupational, or other important areas of functioning or warrants medical evaluation.
• The symptom or deficit is not limited to pain or sexual dysfunction, does not occur exclusively during the course of somatization disorder, and is not better accounted for by another mental disorder.

According to psychodynamic theory, conversion symptoms develop to defend against unacceptable impulses.^[6] The primary gain, that is to say the purpose of a conversion symptom is to bind anxiety and keep a conflict internal. A fairly transparent example would be leg paralysis after an equestrian competitor is thrown from his or her horse. The symptom has a symbolic value that is a representation and partial solution of a deep-seated psychological conflict: to avoid running away like a coward, and yet to avoid being thrown again.

According to learning theory, conversion disorder symptoms are a learned maladaptive response to stress. Patients achieve secondary gain by avoiding activities that are particularly offensive to them, thereby gaining support from family and friends, which otherwise may not be offered.^[9]

Frequency

United States

True conversion reaction is rare.^{[10, 11]} Predisposing factors include extreme psychosocial stress, and perhaps, rural upbringing. Some psychiatrists suspect that western society has incorporated Freudian notions of unconscious motivations and conflicts: conversion reactions have become too obvious to serve their purpose.

• Incidence has been reported to be 11-300 cases per 100,000 people.
• Cultural factors may play a significant role. Symptoms that might be considered a conversion disorder in the US may be a normal expression of anxiety in other cultures.
• One study reports that conversion disorder accounts for 1.2-11.5% of psychiatric consultations for hospitalized medical and surgical patients.

International

At the National Hospital in London, the diagnosis was made in 1% of inpatients.^[12] Iceland's incidence of conversion disorder is reported to be 15 cases per 100,000 persons.

Mortality/Morbidity

Patients diagnosed with conversion disorder may go on to demonstrate serious, traditional medical illness. This has been happening less and less often over the years (29% in 1950s down to 4% in 1990s). Unfortunately, emergency physicians may find themselves sorting out new neurologic symptoms in settings of terrible time pressure: populations statistics may be of little reassurance for any specific individual.

Sex

Sex ratio is not known although it has been estimated that women patients outnumber men by 6:1. This is of little help when evaluating an individual patient.

Age

Conversion disorder may present at any age but is rare in children younger than 10 years or in persons older than 35 years.^[13]

In a University of Iowa study of 32 patients with conversion disorder, however, the mean age was 41 years with a range of 23-58 years.^[14]

In pediatric patients, incidence of conversion is increased after physical or sexual abuse. Incidence also increases in those children whose parents are either seriously ill or have chronic pain.^[15]