Chorea, Huntington's disease

Chorea

Contributed by Shu-Leong Ho, MD, FRCP
Henry G. Leong Professor & Chief of Division
University of Hong Kong, Queen Mary Hospital
Division of Neurology, Dept. of Medicine
Hong Kong

Chorea is an abnormal involuntary movement  derived from the Greek word “dance”. It is characterized by brief, abrupt, irregular, unpredictable, non-stereotyped movements. In milder cases, they may appear purposeful; the patient often appears fidgety and clumsy. They can affect various body parts, and interfere with speech, swallowing, posture and gait. Chorea may worsen with anxiety and voluntary movements, and subsides during sleep. They may occur with athetosis, a more distal, slower, writhing, abnormal movement, and is known as choreoathetosis. In more severe choreiform movements, they appear wild, violent, and may involve flinging of a body part and induce injuries, and is known as ballism. Chorea may also occur with other abnormal movements such as dystonia.

There is a wide range of seemingly unrelated causes, from pregnancy (chorea gravidarum) to inherited forms such as Huntington’s disease and benign hereditary chorea, infection/immune-related such as Sydenham’s chorea and Systemic Lupus Erythematosus, focal vascular lesions in the basal ganglia, drugs such as levodopa, neuroleptics and oral contraception, various metabolic and endocrinological disorders such as hyperthyroidism, hypo/hyperparathyroidism and hypo/hyperglycemia. Its pathophysiology involves a functional dysregulation of the basal ganglia motor circuit, where the final  thalamo-cortical output is increased, resulting in increased movement and chorea.

Treatment of chorea usually entails addressing its root etiology. The most common symptomatic treatment of chorea  include the use of neuroleptic agents, other dopamine depleters such as tetrabenazine, and sometimes benzodiazepines.


Huntington’s disease

Contributed by Hubert Fernandez, MD
Department of Neurology
Cleveland Clinic
Cleveland, Ohio USA

Huntington’s disease is an autosomal dominant neurodegenerative disorder (therefore each child of an affected parent has a 50% chance of developing the disease) due to an abnormal expansion of IT-15 gene on chromosome 4 which encodes for the protein huntingtin. Most people develop Huntington’s disease between 30-54 years old but it can manifest as early as 4 years old and as late as 80 years. Huntington’s disease is clinically characterized by a triad of motor, cognitive and psychiatric symptoms. Motor features include: impairment of involuntary (chorea) and voluntary movements; reduced manual dexterity, slurred speech, swallowing difficulties, balance problems and falls. It may also present with parkinsonism and dystonia in the young (termed the Westphal variant). Cognitive features are characterized initially by loss of speed and flexibility in thinking, but later become more global. Psychiatric features may include: depression (most common), mania, obsessive-compulsive disorder, irritability, anxiety, agitation, impulsivity, apathy, and social withdrawal.

Its definitive diagnosis is through genetic testing. Genetic counseling is required for asymptomatic individuals with a family history. Prenatal testing (as early as 8-10 weeks) is possible. A non-disclosing prenatal test, which determines only whether or not the fetus received a chromosome from the affected grand parent, without determining whether the fetus or the at risk parent actually caries the gene, is possible but requires samples from several individuals.

There are other causes of chorea that may look like Huntington’s disease. Some are genetic such as neuroacanthocytosis, dentatorubropallidolusyian atrophy, Huntington’s disease like-1,2,3 and 4, some of the spinocerebellar ataxias, benign hereditary chorea, Wilson’s disease and mitochondrial disorders. In addition, non-hereditary causes of chorea include: essential chorea, infectious chorea (acute manifestations of bacterial meningitis, encephalitis, tuberculous meningitis, aseptic meningitis, HIV encephalitis, toxoplasmosis have been described), post-infectious/autoimmune choreas (such as Sydenham’s disease [St. Vitus dance], systemic lupus erythematosus, and chorea gravidarum), post-pump chorea, polycythemia vera, vascular chorea, paraneoplastic chorea and drug-induced chorea (acutely with dopaminergic or anti-dopaminergic drugs, anticonvulsants, etc; or tardive chorea: stereotypic oro-buccal-lingual dyskinesia after chronic exposure to dopamine receptor blocking agents).

Non-pharmacologic approaches to some functional difficulties and behavioral dysfunction in Huntington’s disease are important. Dopamine receptor blocking agents may be used if the chorea is disrupting quality of life. Examples of agents used to alleviate chorea include: reserpine, tetrabenazine, and neuroleptics such as haloperidol, risperidone, etc. Stereotactic surgery (DBS) for severe and disabling cases of chorea has been reported.

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2014
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Movement Disorders Journal
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Movement Disorders-Clinical Practice - Coming in 2014!
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