Psychogenic Movement Disorders

Abnormal movements and postures resulting from primary psychiatric disease are a diagnostic dilemma because all types of movement disorders may be mimicked by a psychogenic disease, including akinetic-rigid and hyperkinetic disorders, with the latter more frequent, particularly tremor, myoclonus, and dystonia (Williams et al., 2005; Reich, 2006). Psychogenic movement disorders (PMDs), are a valuable model for all medically unexplained symptoms and raise arduous challenges for diagnosis and treatment indicating our restricted understanding of the true pathogenesis that causes them. A multiplicity of terms such as “hysterical conversion”, “functional”, “psychosomatic”, “neuropsychiatric”, “dissociative motor disorders”,and so on, have been applied to describe neurological symptoms that cannot be attribute to any known organic disease (Mace & Trimble, 1991; Lang, 2006). The term “psychogenic” is the commonest in the movement disorder literature, but there is no unanimity whether it reflects the precise nature of a syndrome containing both neurologic and psychiatric components. By the late-19th century, psychoanalytic theory ruled medical reasoning about these symptoms. Originally referring to these disorders as hysteria, neuropsychiatrists began illustrating the various clinical phenomenological aspects of such disorders. Paralysis, tremors, convulsions and sensory alterations were identified as sometimes being due to hysteria. Subsequently, different etiologies of dystonia, tremor, myoclonus and other movement disorders were recognized. Over the years, newer clinical criteria, laboratory investigations, particularly neurophysiological findings, and improved neuroimaging have provided significant insights about the psychogenicity of the diagnosis. However, a misdiagnosis is possible either on patients originally believed to have a conversion disorder or because PMD was never considered on differential diagnosis (Rosebush & Mazurek, 2006; Lang & Gupta, 2009). The pathophysiology of PMDs are not yet well known, but functional brain imaging studies combined with other neurophysiologic techniques are starting to help understand them (Stone & Carson, 2011). These studies promise an understanding of these symptoms in parallel neurologic and psychiatric ways. The diagnosis of a psychogenic movement disorder is often difficult and the level of diagnostics that the clinician has for PMD varies remarkably, depending on the clinical feature of the movement disorders and the accompanying signs and symptoms. PMDs are