Chorea in an 83‐Year‐Old Woman: Don't Forget Huntington's Disease (2012)

Huntington's disease (HD) is a rare neurodegenerative disorder affecting young adults and characterized by involuntary choreic movements, psychiatric symptoms, and dementia. We report a rare case of late onset of the disease. An 83-year-old woman presented to the Neurology Department with a 3-year history of progressively uncontrollable movements. Her past medical history included hypertension and non-insulin-dependent diabetes mellitus. She was the second of three children and had no children of her own. There was no family history of abnormal movements or mental disease. Before the onset of the movements, she had never taken antidopaminergic medications. The involuntary abnormal movements had begun insidiously 3 years earlier with lower limb jerks mimicking myoclonus. Because no other neurological abnormalities were found, essential myoclonus was initially diagnosed, and oral diazepam was initiated, leading to mild transient improvement. Over the following months, she noted that the movements gradually worsened and spread to her upper extremities and face. Two years later, she complained of gait instability and needed crutches to walk. She never complained of depression, and close relatives reported no psychiatric symptoms. Physical examination revealed generalized choreic movements involving not only the four extremities, but also the trunk, head, and face. Chorea was present at rest and was exacerbated by stress and emotion. In addition, she experienced jerky intrusions when attempting to perform smooth pursuit eye movements. Neurological examination showed moderate dysarthria and gait instability. Although she did not have memory complaints, specific cognitive evaluation revealed memory impairment and dysexecutive dysfunction (Mini-Mental State Examination score 19/30; Mattis Rating Scale score 119/144) without behavioral disturbance. Standard biological data were unremarkable. Diabetes mellitus was well controlled, and thyroid levels were normal. Brain magnetic resonance imaging (MRI) showed only mild leukoaraiosis and no other abnormalities, in particular, no atrophy of caudate nuclei (Figure 1). Because her regular medication was not known to induce choreic movements, genetic testing was proposed with informed consent to exclude HD. Molecular genetic analysis revealed an expanded allele with 40 CAG repeats, confirming the hypothesis. Tetrabenazine was started, which led to a reduction in intensity of chorea, and the woman was referred for genetic counseling and support group. The usual etiologies of senile chorea include drugs, medications, cerebrovascular disease, genetic and sporadic neurodegenerations, and a range of systemic (hematological, metabolic, and immune) disorders.1 Nevertheless, studies have revealed that the majority of individuals with senile chorea have HD.2 HD is a rare autosomal-dominant neurodegenerative disease caused by a CAG expansion in the 5′ region of the HTT gene.3 The normal range of CAG repeats varies from six to 36. Mutations between 36 and 39 repeats are considered to have less penetrance. Onset usually occurs by the fourth to fifth decade of life, but it can present at any age, with a broad range of 2–85 years.4 Diagnosis is made based on clinical features and family history and is then confirmed by genetic testing.3 No complementary examinations aid in diagnosis, even if brain MRI can reveal atrophy of the striatum, especially the caudate nuclei. Although there is no established treatment to delay the onset or forestall the progression of HD, symptomatic treatment of chorea may be beneficial in some individuals, because it may have a favorable effect on motor function, quality of life, and safety. Peculiar clinical characteristics of late-onset HD have been detailed elsewhere.5 As in our case, most (68%) individuals with late onset of the disease are the first in their family to be diagnosed with HD. In these late-onset cases, disease usually begins with motor problems, and disease duration is somewhat shorter than that reported for the midlife-onset form of the disease. Furthermore, serious falls are a major risk, and global dementia may be associated with coincident Alzheimer's disease. Finally, death is often related to aging-associated diseases such as cancer and cerebrovascular disease. Because the majority of individuals with “senile” chorea have HD even in the absence of a family history, the case discussed here is a reminder that the diagnosis of HD should be considered whatever the age. This diagnosis has major consequences for genetic counseling. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. Author Contributions: R. Lefaucheur and L. Guyant-Maréchal: conception of the letter, wrote the first draft. D. Wallon and G. Nicolas: design, subsequent drafts of the letter, critical revisions. E. Tollard: interpretation of radiological data, critical revisions. R. Lefaucheur, L. Guyant-Maréchal, A. Borden, and D. Maltête: letter design, subsequent drafts of the letter, critical revisions, and final approval of the version submitted for publication. Sponsor's Role: No sponsor's role.