Motor and Somatosensory Conversion Disorder: A Functional Unawareness Syndrome?

The authors present a possible neurological explanation of the syndrome of conversion disorder, a syndrome that has traditionally been at the interface of psychiatry and neurology. There are neural and clinical parallels between “lesional unawareness” disorders and somatosensory conversion disorders: right hemisphere-lateralized, large-scale brain network dysfunction may play a significant role in the neurobiology of conversion disorder; this network dysfunction involves the perigenual anterior cingulate and posterior parietal cortical areas, but further research is also needed to clarify the role of affective circuits in conversion disorder.

Although conversion disorder is closely connected to the origins of neurology and psychiatry, it remains poorly understood. In this article, the authors discuss neural and clinical parallels between lesional unawareness disorders and unilateral motor and somatosensory conversion disorder, emphasizing functional neuroimaging/disease correlates. Authors suggest that a functional-unawareness neurobiological framework, mediated by right hemisphere-lateralized, large-scale brain network dysfunction, may play a significant role in the neurobiology of conversion disorder. The perigenual anterior cingulate and the posterior parietal cortices are detailed as important in disease pathophysiology. Further investigations will refine the functional-unawareness concept, clarify the role of affective circuits, and delineate the process through which functional neurologic symptoms emerge.