Chorea in Adults Workup

Updated: Jul 01, 2019
  • Author: Pradeep C Bollu, MD; Chief Editor: Selim R Benbadis, MD  more...
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Workup

Laboratory Studies

Diagnosis of the primary choreatic conditions is based on history and clinical findings; however, several laboratory studies are useful, especially in distinguishing the secondary forms of chorea from the primary forms. Some of them are mentioned here.

  • Huntington disease: The only laboratory study presently available to confirm HD is genetic testing. It identifies a gene abnormality in the short arm of chromosome 4, characterized by abnormal repetition of the trinucleotide CAG, the length of which determines the age of onset (anticipation). [54, 82, 42]  Genetic testing has a sensitivity of 98.8% and a specificity of 100%, making it a valuable test to confirm the diagnosis of HD. [109]

  • Wilson disease [27, 28] : A low serum ceruloplasmin level and serum copper values showing increased urinary copper excretion corroborate the diagnosis in most cases. Persistent aminoaciduria, reflecting a renal tubular abnormality, is present in most but not all patients. Liver function test results are usually abnormal. Serum ammonia levels may be elevated. If the diagnosis is still uncertain, liver biopsy can help confirm the diagnosis.

  • Sydenham chorea [51, 52] : The chorea can lag behind the etiologic streptococcal infection by 1-6 months, sometimes as long as 30 years; therefore, antistreptococcal antibody titers may no longer be elevated at presentation. Without documentation of an antecedent streptococcal infection, the diagnosis of Sydenham chorea must be made by excluding other causes.

  • Neuroacanthocytosis: The diagnosis is confirmed by the presence of spiky erythrocytes (acanthocytes) in peripheral blood smears. The serum creatine kinase level may be elevated. [43]

Other laboratory studies useful in the differential diagnosis of chorea include complement levels, antinuclear antibody titers, antiphospholipid antibody titers, amino acid levels in serum and urine, enzymatic studies from skin fibroblasts, thyrotropin levels, thyroxine values, and parathormone levels.

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Imaging Studies

MRI

Patients with Huntington disease (HD) and chorea-acanthocytosis show decreased signal in the neostriatum, caudate, and putamen. No significant difference has been observed between these diseases. The decreased neostriatal signal corresponds to increased iron deposition. [83, 84] Generalized atrophy, as well as focal atrophy of the neostriatum, predominantly of the caudate, with resulting enlargement of the frontal horns, follows the initial findings of decreased neostriatal signal. [85] Along with the changes in subcortical basal ganglia structures, progressive regional thinning of the cerebral cortex may also be seen in HD. [108]

Most patients with Sydenham chorea show no abnormalities. However, a study reported volumetric differences in the caudate, putamen, and globus pallidus; they were significantly larger in patients with Sydenham chorea than in controls. Patients with hemiballismus demonstrate signal changes in the contralateral subthalamic nucleus or, less often, the striatum or thalamic nuclei. [20]

MRI of the brain of patients with senile chorea shows a decrease in signal intensity throughout the striatum (suggesting iron deposition) [83, 84] and narrowing of the space separating the caudate head and putamen, but no overt atrophy of these structures. [55]

Positron emission tomography

Fluorodopa (F-dopa) uptake is normal or mildly reduced in patients with chorea. HD and chorea-acanthocytosis show bilateral hypometabolism in the caudate nucleus and putamen. [86, 87, 88]

Patients with chorea and dementia show decreased glucose metabolism in the frontal, temporal, and parietal cortices.

Patients with benign hereditary chorea may or may not show decreased metabolism in the caudate. [29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 67, 41]

The finding of normal cerebral glucose metabolism in the striatal region practically excludes HD, this being a useful tool for differential diagnosis. The definite diagnosis of HD is made easily by neurogenetic studies. [54]

Hypometabolism in the caudate nucleus and putamen on the contralateral side is seen in patients with hemichorea.

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