Chapter 7. The Mechanism of Dissociation (2) Conversion ------ Dissociation on the Physical Level (7)

Physical manifestation of dissociative disorder In this section we discuss physical manifestations in dissociative disorders. The terms conversion or conversion disorder are mainly used to denote varieties of physical symptoms which are considered to be of dissociative nature. As I discussed earlier in this chapter, Freud (1894) meant conversion as a process in which “the incompatible idea rendered innocuous by its sum of excitation being transformed into something somatic” (p. 49). However, the way this term is understood is very inconsistent among clinicians. Moreover, many clinicians seem to agree that some traumatic stresses are implicated in the formation of dissociative disorders, and Freud’s theory based on libidinal and conflict model is no longer readily accepted by them.
Freud, S. (1894). The neuro-psychoses of defense. SE, 3: 45-61.
This does not mean, however, that conversion symptoms are understood as a result of traumatic stress, not at least in a way that physiological symptoms of PTSD such as flashbacks are considered to reflect on traumatic experiences. There seems to be several steps between traumatic stress and dissociative disorders. Typically repeated trauma would sensitize an individual to respond to some cues or reminders with dissociation and its physical manifestations.
As we discussed in the chapter 5, the origin of hysteria, a predecessor of dissociative disorder dates back to B.C. 2000, in ancient Egyptian era. Since then hysteria has been documented with mysticism, prejudice, and misunderstanding of many sorts. This was partly because of sudden and eccentric manifestation of its symptoms. It was Briquet (1859) who made a first medical report on hysteria. An already historical term “Briquet syndrome” that we sometimes encounter in the literature demotes hysteria with various physical manifestations, practically synonymous to somatization disorder in DSM-IV-TR. In 19th century, it was Charcot who studied and described hysteria in detail, but his focus is mainly on its somatic symptoms (Ellenberger, 1970). Charcot’s descriptions of hysteria were a mixture of clinical observation based on reality and his theoretical speculations. Freud took over some of Charcot’s ideas although he rejected his theory of the traumatic origin of hysteria later on. Freud’s main focus and interest in hysteria was its somatic manifestations that he conceptualized as conversion, with an assumption that it was basically the patients’ conflict which was transferred onto the somatic level.
Briquet. P. (1859) Traité clinique et thérapeutique de l’hysterie. Bailliere, Paris.　
Ellenberger, H. (1970) The Discovery of the Unconscious: The History and Evolution of Dynamic Psychiatry. Basic Books, New York. Hardcover edition.
Since Freud, terms such as conversion or conversion hysteria have been used by clinicians and now “conversion disorder” is in the formal nomenclature of DSM. However, as I stated already, this does not mean that the mechanism of conversion is well clarified. One of the current problems around this notion is that there is a marked discrepancy of its understanding between DSM and ICD, two major diagnostic system in psychiatry. Since its publication of DSM-III in 1980, conversion disorder has been classified as one of “somatoform disorders”, and therefore treated independently from dissociative disorder. However, in ICD-10, there is a diagnostic category named “dissociative (conversion) disorder”, with an implication that conversion disorder is part of dissociative disorder. Discrepancy of these two diagnostic systems has been a source of confusion for many clinicians.