Introduction

Conversion disorders have existed for many centuries, called by different names, and its nosology has changed at regular intervals. In clinical practice, these are rather common disorders in some countries and considered to be less frequent or rare in other countries. People might have conversion symptoms and when these symptoms form a predominant clinical presentation, a conversion disorder is diagnosed. Conversion symptoms may be reported in other psychiatric disorders as well. The common presentation of conversion disorders is through bodily or neurological symptoms or in loss of function of any particular system or part of body, or occurrence of sensation or pain in relation to psychological or emotional stress. The term conversion has a psychodynamic connotation, wherein the conflict or psychic anxiety was considered to be “converted” into a loss of function of a bodily part.

Historical aspects

The first description of conversion disorders is found in ancient times of Hippocrates and Galen. Greek physicians, who considered the symptoms to be specific to women, called it hysteria, which meant “a wandering uterus, hustera.” The term conversion was first used by Freud and Breuer to refer to the substitution of a somatic symptom for a repressed idea. This introduced the psychological concept of primary gain, (i.e., psychological anxiety is converted into a somatic symptom), and secondary gain of such a reaction is the subsequent benefit that a patient may derive from being in the “sick role” [1]. Conversion disorder has always remained at the interface between neurology and psychiatry since the days of Charcot, Breuer, and Freud.

Like any poorly understood phenomenon or disorder, there are many theories explaining the development of conversion disorders, namely, psychodynamic, behavioural, learning, sociocultural, philosophical, and neurobiological. Conversion disorder is conceptualised as a disorder of the brain associated with disordered emotions, in those with certain personality traits and inappropriate coping to stress, which helps the person avoid the stress rather than face it [2].

Epidemiology: Where are the conversion disorders of yesteryear?

Conversion disorders are universal in their presentation. These are one of the common presentations of common mental disorders or neurosis. In the last five or six decades, conversion disorders have been reported less commonly in the Western and developed countries. It was considered that conversion disorders are a common form of presentation of reaction to the stress in some traditional societies. One Indian epidemiological survey repeated 10 years and 15 years later in the same settings, which confirmed that the prevalence of conversion disorders or hysteria is on the wane [3]. The decline in hysteria was probably due to the improved socioeconomic status of women, because of greater economic power in the younger age group [4]. and increasing psychological sophistication of the population . The proportion of patients diagnosed as dissociative disorders during a decade in a psychiatric hospital ranged between 1.5 and 15.0 per 1000, reiterating the fact that dissociative disorders continue to exist and form a sizable proportion of mental disorders [5]. Of these, two-thirds of the cases were dissociative motor disorders and dissociative convulsions (conversion disorders) and were the most frequent [5]. The total incidence of conversion disorder has been estimated at 2.5–500 per 100,000 in the general population and at 20–120 per 100,000 among hospital inpatients [6]. In clinical practice, psychiatrists come across both conversion symptoms in depressive or anxiety disorders, as well as conversion disorders. Somatoform disorders are a common differential diagnosis for conversion, discussed later in the chapter.

In this chapter dissociative disorders would also be considered under conversion disorders.

Terminology: There’s a lot in a name!

It is not an easy task to provide suitable names for symptoms unexplained by underlying organic pathology; hence, these have to meet certain criteria and description. The preferred term should be acceptable and of use to patients and doctors in a way that facilitates appropriate treatment. Despite being in official nomenclature since 1935, “conversion” has not achieved the dominance as a term among clinicians and researchers that might have been hoped for [7]. The term should also reflect etiological neutrality about the nature of a problem that we still do not properly understand. The term conversion disorder implies a specific psychological etiology in which intrapsychic distress is “converted” into “somatic” symptoms, thereby reducing the distress. Thus, it is not etiologically neutral. While not necessarily wrong, the conversion hypothesis is as yet unproven and must compete with other plausible psychological and biopsychosocial theories [7].

In clinical practice, a wide variety of terminology is used between countries and between physicians, neurologists, psychiatrists, and other health care providers (see below).

Stone and colleagues [7] have suggested, like many others, that the name conversion disorder should be changed. According to them, conversion disorder is not a useful term for this group of symptoms. Functional neurological symptom disorder, dissociative neurological symptom disorder and psychogenic neurological symptom disorder are possible alternatives suggested by them. One could take these suggestions with a pinch of salt. The term “functional” is poorly understood: Does it mean loss of function of a body part (as in monoparesis) or defect in function of the brain in the lack of anatomical and pathological evidences for the symptom. It perhaps implies a lack of morphological or biochemical abnormality; nevertheless the functions are impaired. With the growing use of functional magnetic resonance imaging fMRI, the term functional would add to the confusion, that functional disorders need a functional MRI. The term dissociative, like conversion, has its roots in psychodynamic defense mechanism. Psychogenic would imply the role of psychological factors and confirm their role in causing the symptoms and being an etiological term.

The arguments [8, 9] for abandoning the term conversion disorder, summarised by Reynolds [10], reiterate that the concept of conversion is based on a questionable psychoanalytical concept, and it is not widely used by general physicians and neurologists, and some assume it is not liked by patients. The current conversion diagnostic criteria require a psychosocial association with onset of symptoms, which is difficult to find in a minority of patients, and when present is sometimes of questionable relevance; and the exclusion of malingering, which is difficult, if not impossible. Neurologists tend to use their own terminology and concepts, commonly “functional” but with a variety of meanings, most often “non-organic” [11]. The heterogeneity of conversion disorders does not make it any easier to select a suitable, acceptable name for such disorders.