Chorea is a hyperkinetic movement disorder characterized by uncontrolled, excessive motion. Derived from the Greek word for “dance,” this neurological condition involves involuntary movements ranging from subtle fidgeting to severe, continuous flailing of the limbs. Chorea is a symptom of an underlying neurological issue, often related to dysfunction in the brain’s motor control pathways.
Identifying chorea is important due to the wide range of potential causes, some of which are treatable. It significantly impacts a person’s ability to perform routine activities. Pinpointing the specific cause allows for appropriate management strategies and, where possible, disease modification.
Defining Chorea and Its Manifestation
Chorea is defined by involuntary, rapid, and irregular movements that are non-rhythmic and flow randomly across the body. These movements can affect any muscle group, including the face, trunk, and extremities.
A characteristic feature is motor impersistence, the inability to maintain a steady posture or sustained voluntary action. For example, a person asked to hold a sustained grip may repeatedly relax and tighten their hand, known as “milkmaid’s grip.” This motor instability also affects the tongue, causing it to dart in and out when protruded.
Chorea is distinct from other hyperkinetic disorders like tremor, which is rhythmic, or tics, which are partially suppressible. The movements are less slow and writhing than athetosis. When chorea is severe and involves large, flinging motions of the proximal limbs, it is referred to as ballism.
The presence of chorea interferes with daily functioning, affecting fine motor skills, gait, speech (dysarthria), and swallowing (dysphagia). While these movements disappear during sleep, they cause difficulties with balance, self-feeding, and dressing while awake.
Primary Causes of Chorea
The causes of chorea are broadly categorized into hereditary and acquired conditions. The disorder results from functional dysregulation within the basal ganglia, the brain structure responsible for regulating movement. This disruption can be caused by structural damage, genetic mutations, or autoimmune processes.
Hereditary Causes
Huntington’s disease (HD) is the most recognized genetic cause of chronic chorea in adults. This progressive neurodegenerative disorder is caused by an expansion of a CAG trinucleotide repeat in the HTT gene. Chorea in HD is part of a symptom triad that includes cognitive decline and psychiatric changes.
Other genetic conditions can also cause chorea. Benign hereditary chorea is a rare, non-progressive form often beginning in childhood, frequently caused by mutations in the TITF-1 gene. Inherited metabolic disorders, such as Wilson disease (copper accumulation) or neuroacanthocytosis, can also result in chorea.
Acquired/Secondary Causes
Acquired causes often involve an acute or subacute onset of the movement disorder. Sydenham’s chorea, an autoimmune form, is the most common cause in children and adolescents. It is a delayed manifestation of a streptococcal infection, occurring as part of acute rheumatic fever.
Metabolic and endocrine abnormalities can trigger chorea, which may resolve once the underlying condition is treated. Examples include hyperthyroidism, hypoglycemia, nonketotic hyperglycemia, or liver failure. Vascular events, such as a stroke affecting the basal ganglia, can also cause an acute onset of chorea, sometimes manifesting as unilateral ballism.
Chorea can also be induced by certain medications (iatrogenic chorea), such as dopamine-blocking agents or drugs used to treat Parkinson’s disease (e.g., levodopa). Autoimmune disorders, including systemic lupus erythematosus, can also target the basal ganglia and result in chorea.
Clinical Evaluation and Diagnostic Steps
The diagnostic process begins with a detailed patient history and a thorough neurological examination to confirm chorea and differentiate it from other movement disorders. Physicians inquire about the movement characteristics and any cognitive or psychiatric symptoms. A comprehensive family history is obtained to screen for hereditary conditions like Huntington’s disease.
Laboratory Studies
Laboratory studies evaluate for acquired or secondary causes. Blood tests check for evidence of recent streptococcal infection (for suspected Sydenham’s chorea), metabolic disturbances (like abnormal blood glucose or thyroid hormone levels), and autoimmune markers. Testing for certain genetic conditions, such as Wilson disease, may also be performed via blood samples.
Imaging and Genetic Testing
Neuroimaging, typically magnetic resonance imaging (MRI) or computed tomography (CT) scans, identifies structural lesions or abnormalities in the brain. These scans detect evidence of stroke, tumors, or the characteristic atrophy of the caudate nucleus seen in advanced Huntington’s disease, helping rule out structural damage.
If a hereditary cause is suspected, targeted genetic testing is performed. For Huntington’s disease, this involves analyzing the number of CAG repeats in the HTT gene. Genetic counseling is a prerequisite for this testing to ensure the patient understands the implications of the results.
Therapeutic Approaches to Managing Chorea
Treatment for chorea aims to manage symptoms and address the underlying cause, as many conditions are not curable. If a reversible cause is identified, such as drug-induced chorea or metabolic imbalance, the first action is discontinuing the medication or correcting the metabolic issue. For Sydenham’s chorea, treatment involves antibiotics for the infection and immunosuppressive therapies like corticosteroids to manage the autoimmune response.
For symptomatic management, pharmacological interventions suppress excessive motion, often targeting the brain’s dopamine system due to associated increased dopaminergic activity. These include dopamine receptor blockers, such as antipsychotics, and vesicular monoamine transporter 2 (VMAT2) inhibitors.
VMAT2 inhibitors—including tetrabenazine, deutetrabenazine, and valbenazine—work by reducing the amount of dopamine available in the brain’s synapses. This class of medication is specifically approved for treating chorea associated with Huntington’s disease. Other agents, such as anti-epileptic or GABAergic drugs, may be used as adjunct therapies to reduce movement severity.
Non-pharmacological support focuses on maintaining function and patient safety. Physical and occupational therapy help individuals adapt to movement difficulties, improving balance and coordination to reduce fall risk. Speech therapy addresses difficulties with articulation and swallowing caused by involuntary movements.