The essential feature of Conversion Disorder is the presence of symptoms or deficits affecting voluntary motor or sensory function that suggest a neurological or other general medical condition (Criterion A). Psychological factors are judged to be associated with the symptom or deficit, a judgment based on the observation that the initiation or exacerbation of the symptom or deficit is preceded by conflicts or other stressors (Criterion B). The symptoms are not intentionally produced or feigned, as in Factitious Disorder or Malingering (Criterion C). Conversion Disorder is not diagnosed if the symptoms or deficits are fully explained by a neurological or other general medical condition, by the direct effects of a substance, or as a culturally sanctioned behavior or experience (Criterion D). The problem must be clinically significant as evidenced by marked distress; impairment in social, occupational, or other important areas of functioning; or the fact that it warrants medical evaluation (Criterion E). Conversion Disorder is not diagnosed if symptoms are limited to pain or sexual dysfunction, occur exclusively during the course of Somatization Disorder, or are better accounted for by another mental disorder (Criterion F).
Conversion symptoms are related to voluntary motor or sensory functioning and are thus referred to as “pseudoneurological.” Motor symptoms or deficits include impaired coordination or balance, paralysis or localized weakness, aphonia, difficulty swallowing or a sensation of a lump in the throat, and urinary retention. Sensory symptoms or deficits include loss of touch or pain sensation, double vision, blindness, deafness, and hallucinations. Symptoms may also include seizures or convulsions. The more medically naive the person, the more implausible are the presenting symptoms. More sophisticated persons tend to have more subtle symptoms and deficits that may closely simulate neurological or other general medical conditions.
A diagnosis of Conversion Disorder should be made only after a thorough medical investigation has been performed to rule out an etiological neurological or general medical condition. Because a general medical etiology for many cases of apparent Conversion Disorder can take years to become evident, the diagnosis should be reevaluated periodically. In early studies, general medical etiologies were later found in from one-quarter to one-half of persons initially diagnosed with conversion symptoms. In more recent studies, misdiagnosis is less evident, perhaps reflecting increased awareness of the disorder, as well as improved knowledge and diagnostic techniques. A history of other unexplained somatic (especially conversion) or dissociative symptoms signifies a greater likelihood that an apparent conversion symptom is not due to a general medical condition, especially if criteria for Somatization Disorder have been met in the past.
Conversion symptoms typically do not conform to known anatomical pathways and physiological mechanisms, but instead follow the individual’s conceptualization of a condition. A “paralysis” may involve inability to perform a particular movement or to move an entire body part, rather than a deficit corresponding to patterns of motor innervation. Conversion symptoms are often inconsistent. A “paralyzed” extremity will be moved inadvertently while dressing or when attention is directed elsewhere. If placed above the head and released, a “paralyzed” arm will briefly retain its position, then fall to the side, rather than striking the head. Unacknowledged strength in antagonistic muscles, normal muscle tone, and intact reflexes may be demonstrated. An electromyogram will be normal. Difficulty swallowing will be equal with liquids and solids. Conversion “anesthesia” of a foot or a hand may follow a so-called stocking-glove distribution with uniform (no proximal to distal gradient) loss of all sensory modalities (i.e., touch, temperature, and pain) sharply demarcated at an anatomical landmark rather than according to dermatomes. A conversion “seizure” will vary from convulsion to convulsion, and paroxysmal activity will not be evident on an EEG.
Even when following such guidelines carefully, caution must be exercised. Knowledge of anatomical and physiological mechanisms is incomplete, and available methods of objective assessment have limitations. A broad range of neurological conditions may be misdiagnosed as Conversion Disorder. Prominent among them are multiple sclerosis, myasthenia gravis, and idiopathic or substance-induced dystonias. However, the presence of a neurological condition does not preclude a diagnosis of Conversion Disorder. As many as one-third of individuals with conversion symptoms have a current or prior neurological condition. Conversion Disorder may be diagnosed in the presence of a neurological or other general medical condition if the symptoms are not fully explained given the nature and severity of the neurological or other general medical condition.
Traditionally, the term conversion derived from the hypothesis that the individual’s somatic symptom represents a symbolic resolution of an unconscious psychological conflict, reducing anxiety and serving to keep the conflict out of awareness (“primary gain”). The individual might also derive “secondary gain” from the conversion symptom – that is, external benefits are obtained or noxious duties or responsibilities are evaded. Although the DSM-IV criteria set for Conversion Disorder does not necessarily imply that the symptoms involve such constructs, it does require that psychological factors be associated with their onset or exacerbation. Because psychological factors are so ubiquitously present in relation to general medical conditions, it can be difficult to establish whether a specific psychological factor is etiologically related to the symptom or deficit. However, a close temporal relationship between a conflict or stressor and the initiation or exacerbation of a symptom may be helpful in this determination, especially if the person has developed conversion symptoms under similar circumstances in the past.
Although the individual may derive secondary gain from the conversion symptom, unlike in Malingering or Factitious Disorder the symptoms are not intentionally produced to obtain the benefits. The determination that a symptom is not intentionally produced or feigned can also be difficult. Generally, it must be inferred from a careful evaluation of the context in which the symptom develops, especially relative to potential external rewards or the assumption of the sick role. Supplementing the person’s self-report with additional sources of information (e.g., from associates or records) may be helpful.
Conversion Disorder is not diagnosed if a symptom is fully explained as a culturally sanctioned behavior or experience. For example, “visions” or “spells” that occur as part of religious rituals in which such behaviors are encouraged and expected would not justify a diagnosis of Conversion Disorder unless the symptom exceeded what is contextually expected and caused undue distress or impairment. In “epidemic hysteria,” shared symptoms develop in a circumscribed group of people following “exposure” to a common precipitant. A diagnosis of Conversion Disorder should be made only if the individual experiences clinically significant distress or impairment.