Conversion disorder is often associated with dissociative symptoms, such as deperson- alization, derealization, and dissociative amnesia, particularly at symptom onset or during attacks.
The diagnosis of conversion disorder does not require the judgment that the symptoms are not intentionally produced (i.e., not feigned), as the definite absence of feigning may not be reliably discerned. The phenomenon of la belle indifférence (i.e., lack of concern about the nature or implications of the symptom) has been associated with conversion disorder but it is not specific for conversion disorder and should not be used to make the diagnosis.
Similarly the concept of secondary gain (i.e., when individuals derive external benefits such as money or release from responsibilities) is also not specific to conversion disorder and particularly in the context of definite evidence for feigning, the diagnoses that should be considered instead would include factitious disorder or malingering (see the section ”Dif- ferential Diagnosis” for this disorder).
Transient conversion symptoms are common, but the precise prevalence of the disorder is unknown. This is partly because the diagnosis usually requires assessment in secondary care, where it is found in approximately 5% of referrals to neurology clinics. The incidence of individual persistent conversion symptoms is estimated to be 2—5/ 100,000 per year.
Onset has been reported throughout the life course. The onset of non-epileptic attacks peaks in the third decade, and motor symptoms have their peak onset in the fourth decade.
The symptoms can be transient or persistent. The prognosis may be better in younger chil— dren than in adolescents and adults.
Temperamental. Maladaptive personality traits are commonly associated with conver- sion disorder.
Environmental. There may be a history of childhood abuse and neglect. Stressful life events are often, but not always, present.
Genetic and physiological. The presence of neurological disease that causes similar symp- toms is a risk factor (e.g., non-epileptic seizures are more common in patients who also have epilepsy).
Course modifiers. Short duration of symptoms and acceptance of the diagnosis are pos— itive prognostic factors. Maladaptive personality traits, the presence of comorbid physical disease, and the receipt of disability benefits may be negative prognostic factors.
Changes resembling conversion (and dissociative) symptoms are common in certain culturally sanctioned rituals. If the symptoms are fully explained within the particular cultural context and do not result in clinically significant distress or disability, then the di- agnosis of conversion disorder is not made.
Conversion disorder is two to three times more common in females.
Functional Consequences of Conversion Disorder
Individuals withconversion symptoms may have substantial disability. The severity of dis- ability can be similar to that experienced by individuals with comparable medical diseases.
If another mental disorder better explains the symptoms, that diagnosis should be made.
However the diagnosis of conversion disorder may be made in the presence of another mental disorder.
Neurological disease. The main differential diagnosis is neurological disease that might better explain the symptoms. After a thorough neurological assessment, an unexpected neurological disease cause for the symptoms is rarely found at follow up. However, reas- sessment may be required if the symptoms appear to be progressive. Conversion disorder may coexist with neurological disease.
Somatic symptom disorder. Conversion disorder may be diagnosed in addition to so- matic symptom disorder. Most of the somatic symptoms encountered in somatic symptom disorder cannot be demonstrated to be clearly incompatible with pathophysiology (e.g., pain, fatigue), whereas in conversion disorder, such incompatibility is required for the di- agnosis. The excessive thoughts, feelings, and behaviors characterizing somatic symptom disorder are often absent in conversion disorder.