Overview of rare movement disorders.

Movement disorders that are infrequently seen in clinical practice can be difficult to recognize and accurately diagnose. Familiarity with these disorders can help the clinician distinguish them from more common movement disorders, such as Parkinson disease, which is associated with a significantly different prognosis and treatment approach. Rare disorders with predominate parkinsonism include multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration, whereas Huntington disease is the primary movement disorder characterized by chorea. This chapter will provide an overview of the diagnostic, pathologic, and imaging advances from recent literature as well as discuss current treatments for these rare movement disorders.