Un nouveau regard sur la sémiologie motrice en psychiatrie : de la physiologie du mouvement moteur volontaire aux résultats d'imagerie fonctionnelle dans les troubles de conversion

Are the conversion disorders beyond medical disorders? Lived as a reality by the patient, the absence of “objectives” signs at the clinical examination have for a long time considered these conversion disorders as “pathologies without substrates”. However, if the clinic of these disorders is well known, its precise understanding remains subject to debate and the exact mechanisms that produce it are poorly understood. Does the fact that explanatory lesions in the brain are not found, exclude the possibility of functional abnormalities in this organ? It is often called these disorders “disease of the imagination or the will”, but in fact, we know little about the brain functioning of voluntary motor movement and mental representation in conversion disorders. So with this in mind, what could be the contribution of “modern” techniques of investigations such as functional imaging? Would the identification of functional abnormalities in the brain allow opening new theoretical perspectives for these patients? Functional imaging has explored more complex mechanisms considered some years ago as inaccessible (e.g. emotions, affective states, volition, mental imagery, unconscious processes), and we propose in this paper to show how, using these techniques, a pathology considered as a diagnosis of exclusion and a disorder without substrate can be approached differently through “new” neurophysiological explanation.