Conversion, Factitious Disorder and Malingering: A Distinct Pattern or a Continuum?

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This chapter is aimed at highlighting the recent findings concerning physiopathology, diagnosis, and management of conversion, factitious disorder, and malingering. Conversion disorder is the unintentional production of neurological symptom, whereas malingering and factitious disorder represent the voluntary production of symptoms with internal or external incentives. They have a close history and this has been frequently confounded. Practitioners are often confronted to medically unexplained symptoms; they represent almost 30% of neurologist's consultation. The first challenge is to detect them, and recent studies have confirmed the importance of "positive" clinical bedside signs based on incoherence and discordance, such as the Hoover's sign for the diagnosis of conversion disorder. Functional neuroimaging has allowed a better understanding of the pathophysiology, and highlighted abnormal cerebral activation patterns in conversion disorder in relation to motor, emotional, and limbic networks, different from feigners. This supports the theory evoked by Charcot of a "psychodynamic lesion," which is also reflected by the new term introduced in the DSM-5: functional neurological disorder. Multidisciplinary therapy is recommended with behavioral cognitive therapy, antidepressant to treat frequent comorbid anxiety or depression, and physiotherapy. Factitious disorder and malingering should be clearly delineated from conversion disorder. Factitious disorder should be considered as a mental illness and more research on its physiopathology and treatment is needed, when malingering is a non-medical condition encountered in medico-legal cases.