Seminar on choreas

Summary

Chorea is one of the major types of involuntary movement disorders originating from dysfunctional neuronal networks interconnecting the basal ganglia and frontal cortical motor areas. The syndrome is characterised by a continuous flow of random, brief, involuntary muscle contractions and can result from a wide variety of causes. Diagnostic work-up can be straightforward in patients with a positive family history of Huntington's disease or acute-onset hemichorea in patients with lacunar stroke, but it can be a challenging and complex task in rare autoimmune or genetic choreas. Principles of management focus on establishing an aetiological classification and, if possible, removal of the cause. Preventive strategies may be possible in Huntington's disease where genetic counselling plays a major part. In this review we summarise the current understanding of the neuroanatomy and pathophysiology of chorea, its major aetiological classes, and principles of diagnostic work-up and management.

Introduction

The term “chorea” entered medical writings through descriptions of religiously inspired outbreaks of mass hysteria in the middle ages—coincident with outbreaks of the plague in central Europe—when pilgrims engaged in ecstatic jumping or dancing movements for hours on end to the point of delirium and exhaustion.¹ These rituals were associated with various saints the worshippers called on, of whom Saint Vitus became the most widely known, and “Saint Vitus Dance” persisted as a synonymous term for chorea in 20th century textbooks of neurology. Paracelsus was probably the first to make a distinction between “chorea naturalis” (a true organic medical disorder) and non-organic forms, which he classified into “chorea imaginativa” and “chorea lasciva”.² Thomas Sydenham further developed the concept of organic causes of chorea in the late 17th century with his description of childhood chorea.³ The association between Sydenham's chorea, rheumatic fever, and endocarditis, however, was not appreciated before the 19th century, by which time there was also clear recognition of hereditary chorea through the concise report by George Huntington on affected families in the state of New York.⁴ Today, chorea is recognised as one of the major categories of movement disorders caused by dysfunctional neuronal networks connecting the basal ganglia and motor cortical areas. Choreas can be associated with a plethora of different causes.