Despite this theoretical confusion, conversion disorder continues to be used as a diagnosis in modern psychiatry. Conversion symptoms are often mistaken as neurological disorder, especially when sensations and voluntary movements are altered or impaired. According to a study, 4% of those who visit neurologists have conversion disorders (Parker and Parker, 2004).
Parker, J.N., Parker, P.M. E.D.: Conversion Disorder －A Medical Dictionary, Bibliography, and Annotated Research Guide to Internet References. ICON Group International, Inc. 2004.
Causal relationship between trauma and conversion disorder is not clarified in diagnostic criteria in DSM-IV-TR. Only “psychological factors”, “conflicts” or “stressors” need to be “judged, in the clinician's belief, to be associated with the symptom or deficit” for conversion disorder to be diagnosed. Epidemiological data do not indicate conversion’s relationship with trauma either. According to some report, 22~44 % of conversion disorder patients have physical abuse, and 22~24% of them have sexual abuse (Aybek, 2008).
Aybek, S., Kanaan, R.A., Anthony, S., David, A.S.：The Neuropsychiatry of Conversion Disorder. Current Opinion in Psychiatry, 21;275–280, 2008.It is to be noted, that Freud’s notion of conversion itself was based on the conflict mode, not the trauma model. That itself has a discrepancy from trauma model. Also what conversion contains is not voluntary muscle movement and perceptual disturbance, but autonomic symptoms as well.
Structural dissociation and somatic symptoms
I stated above that current diagnostic criteria as well as epidemiological data do not necessarily reflect on the causal relationship between trauma and conversion. However, there is a theory which makes a very clear case that dissociation and conversion is related to trauma. This is “structural dissociation” theory (van der Hart, et al, 2006). Based on this theory, dissociation is due to traumatic experiences and conversion symptoms can be understood in this context, as this theory assumes that conversion is somatic manifestations of dissociation.
Van Der Hart, O., Ellert R. S. Nijenhuis, E.R.S., Steele, K.: Haunted Self: Structural Dissociation And the Treatment of Chronic Traumatization. W. W. Norton & Co Inc., New York, 2006.
Dissociation might appear to be a new diagnostic entity in the modern psychiatry, but it was documented on a highly sophisticated level by Pierre Janet (1884, 1894, 1898) a century ago. Largely drawing on Janet’s work, three modern psychologists, van der Hart, O., Steele, K, and Nijenhuis, ERS. established a system of theories that they call “structural dissociation”. The gist of their theory is that due to chronic trauma, there is a structural change in our mind. When traumatized, our mind splits into two mental systems that they call “apparently normal personality”(ANP) and “emotional personality”(EP) borrowing the ideas of Charles Myers (1940).
Janet, P. (1889). Líautomatisme psychologique. Paris: Félix Alcan.
Janet, P. (1894). Histoire d'une idée fixe. Revue Philosophique, 37(I), 121-163.
Janet, P. (1898). Névroses et idées fixes. Paris: Félix Alcan.
Myers, C.S. (1940). Shell shock in France 1914-18. Cambridge: Cambridge University Press.
In this theory of structural dissociation, what is most relevant to the discussion in this chapter is his two sets of notions: Psychoform dissociation and Somatoform dissociation, as well as positive and negative symptoms of dissociation. Notions of Psychoform and Somatoform dissociation imply that dissociation typically has two ways of manifestations, and both of them should be equally recognized and treated. According to this theory, there is already an answer to a question as to whether conversion is part of dissociation or not. Another set of notions, i.e., positive and negative symptoms of dissociation is practically the same as what I proposed in my previous work (Okano, 2007). These notions help us understand that conversion symptoms not only involve manifestations of decreased or lack of sensation or voluntary movement, such as sensory and motor paralysis, but also include abnormal perception and movement, such as paresthesia and involuntary movement.
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