Clinical Approach to Chorea
Comprehensive Practical Framework1. Symptom Overview
Understanding the clinical significance and classification of Chorea
Chorea represents one of the most recognizable hyperkinetic movement disorders, yet its presence demands a thorough diagnostic evaluation. Huntington disease, the most common hereditary cause, affects approximately 5 to 10 per 100,000 individuals in populations of European descent. Sydenham chorea, historically the most common cause of childhood chorea, still occurs in regions where rheumatic fever remains prevalent. In adults presenting with new-onset chorea, the differential diagnosis extends far beyond Huntington disease to include drug-induced, autoimmune, metabolic, and vascular etiologies—many of which are treatable or reversible.
Definition
Chorea (from the Greek “choreia,” meaning dance) is an involuntary hyperkinetic movement disorder characterized by irregular, unpredictable, brief, non-rhythmic movements that flow randomly from one body part to another. The movements appear purposeless and cannot be suppressed voluntarily, though patients may incorporate them into semi-purposeful actions (“parakinesia”). When movements are large amplitude and proximal, the term “ballism” is applied, representing the severe end of the choreiform spectrum.
Classification by Duration
| Category | Duration | Common Causes | Clinical Significance |
|---|---|---|---|
| Acute | Less than 2 weeks | Stroke, drug-induced, metabolic derangement, Sydenham chorea onset | Often requires urgent evaluation; many causes are reversible |
| Subacute | 2 weeks to 6 months | Autoimmune encephalitis, paraneoplastic syndrome, Sydenham chorea, HIV-associated | Suggests inflammatory or autoimmune etiology; warrants immunological workup |
| Chronic | Greater than 6 months | Huntington disease, neuroacanthocytosis, benign hereditary chorea, tardive dyskinesia | Neurodegenerative or structural cause more likely; genetic testing often indicated |
Classification by Etiology
Hereditary Causes
Huntington disease: Most common hereditary cause; autosomal dominant with CAG repeat expansion in the HTT gene. Onset typically between ages 30 and 50.
Huntington disease-like syndromes: Include HDL1 through HDL4, spinocerebellar ataxias (especially SCA17), and dentatorubral-pallidoluysian atrophy.
Neuroacanthocytosis syndromes: Chorea-acanthocytosis and McLeod syndrome; associated with acanthocytes on blood smear.
Wilson disease: Autosomal recessive copper metabolism disorder; treatable if diagnosed early.
Benign hereditary chorea: Non-progressive; caused by NKX2-1 mutations affecting thyroid, lung, and brain.
Acquired Causes
Drug-induced: Dopaminergic medications, neuroleptics (tardive), stimulants, anticonvulsants, oral contraceptives.
Autoimmune: Sydenham chorea, anti-NMDA receptor encephalitis, systemic lupus erythematosus, antiphospholipid syndrome.
Vascular: Stroke affecting subthalamic nucleus or striatum; often presents as hemichorea-hemiballismus.
Metabolic: Non-ketotic hyperglycemia, hyperthyroidism, hypoparathyroidism, hepatic encephalopathy.
Infectious: HIV, Creutzfeldt-Jakob disease, viral encephalitis.
Classification by Distribution
| Pattern | Description | Suggests |
|---|---|---|
| Generalized chorea | Involves face, trunk, and all four limbs symmetrically or near-symmetrically | Huntington disease, Sydenham chorea, drug-induced, metabolic causes |
| Hemichorea | Unilateral involvement of arm and leg on the same side | Contralateral basal ganglia lesion (stroke, tumor, hyperglycemia) |
| Hemiballismus | Severe, large-amplitude proximal hemichorea with flinging movements | Subthalamic nucleus lesion (classically stroke); also hyperglycemia |
| Orofacial predominant | Primarily involves mouth, tongue, and facial muscles | Tardive dyskinesia, edentulous elderly, neuroacanthocytosis |
| Focal chorea | Limited to one limb or body region | Structural lesion, post-stroke, localized pathology |
Clinical Context by Age of Onset
| Age Group | Most Likely Causes | Key Considerations |
|---|---|---|
| Young adults (18-30 years) | Drug-induced, Sydenham chorea, Wilson disease, juvenile Huntington disease, autoimmune | Always exclude Wilson disease (treatable); consider autoimmune etiologies |
| Middle-aged (30-50 years) | Huntington disease, drug-induced, autoimmune, vascular | Classic age range for Huntington disease; family history critical |
| Older adults (greater than 50 years) | Tardive dyskinesia, vascular, hyperglycemic, senile chorea, late-onset Huntington disease | Vascular risk factors important; hyperglycemia common cause of acute hemichorea |
Key Concept — The “Treatable Causes” Priority: While Huntington disease is the most common hereditary cause, the clinician’s primary responsibility is to identify treatable and reversible causes of chorea. These include drug-induced chorea, Wilson disease (in patients under 50), autoimmune and paraneoplastic syndromes, metabolic derangements (especially hyperglycemia), and structural lesions. A systematic approach ensures these diagnoses are not missed.
2. Pathophysiology and Mechanisms
Understanding the underlying mechanisms of Chorea
Chorea results from dysfunction of the basal ganglia circuitry, specifically an imbalance between the direct and indirect motor pathways. Understanding these pathways is essential for comprehending why diverse conditions—from neurodegeneration to metabolic disturbance—can produce clinically similar choreiform movements. The common final pathway involves reduced inhibitory output from the globus pallidus internus to the thalamus, resulting in excessive thalamocortical excitation and unwanted movement.
Basal Ganglia Motor Circuitry
| Component | Structure | Function in Movement |
|---|---|---|
| Input Nucleus | Striatum (caudate and putamen) | Receives cortical glutamatergic input; initiates processing through direct and indirect pathways |
| Direct Pathway | Striatum → Globus pallidus internus → Thalamus | Facilitates movement; uses D1 dopamine receptors; GABA/substance P neurons |
| Indirect Pathway | Striatum → Globus pallidus externus → Subthalamic nucleus → Globus pallidus internus | Inhibits movement; uses D2 dopamine receptors; GABA/enkephalin neurons |
| Output Nuclei | Globus pallidus internus and substantia nigra pars reticulata | Provide tonic GABAergic inhibition to thalamus; regulate motor output |
| Modulator | Substantia nigra pars compacta | Provides dopaminergic input to striatum; modulates pathway balance |
How Chorea Develops: The Indirect Pathway Hypothesis
The Core Mechanism
Chorea results primarily from dysfunction of the indirect pathway, leading to reduced inhibitory output from the globus pallidus internus to the thalamus. This causes excessive thalamocortical drive and unwanted movements. In Huntington disease, early preferential degeneration of indirect pathway medium spiny neurons (expressing D2 receptors and enkephalin) produces chorea, while later involvement of direct pathway neurons leads to the akinetic-rigid phenotype seen in advanced disease.
Step-by-Step Mechanism:
- Indirect pathway damage: Loss of striatal neurons projecting to globus pallidus externus
- Globus pallidus externus disinhibition: Increased activity suppresses subthalamic nucleus
- Subthalamic nucleus hypoactivity: Reduced excitatory drive to globus pallidus internus
- Globus pallidus internus hypoactivity: Reduced inhibition of thalamus
- Thalamic disinhibition: Excessive excitatory output to motor cortex
- Unwanted movement: Random, excessive motor cortex activation produces chorea
Key Neurotransmitter Systems
Dopamine
Role: Modulates striatal activity via D1 (direct pathway) and D2 (indirect pathway) receptors
In chorea: Relative dopamine excess or D2 receptor hypersensitivity worsens chorea
Clinical relevance: Dopamine-blocking agents reduce chorea; dopaminergic drugs can induce or worsen it
GABA
Role: Primary inhibitory neurotransmitter in basal ganglia circuits
In chorea: Loss of GABAergic medium spiny neurons disrupts pathway balance
Clinical relevance: GABAergic medications (valproate, clonazepam) may provide symptomatic benefit
Glutamate
Role: Excitatory transmission from cortex to striatum and subthalamic nucleus to output nuclei
In chorea: Excitotoxicity may contribute to neuronal death in Huntington disease
Clinical relevance: NMDA receptor antibodies in autoimmune encephalitis produce chorea
How Specific Conditions Cause Chorea
| Condition | Mechanism | Treatment Implication |
|---|---|---|
| Huntington disease | Mutant huntingtin protein causes selective degeneration of indirect pathway medium spiny neurons; early D2-neuron loss leads to chorea | Vesicular monoamine transporter 2 inhibitors (tetrabenazine, deutetrabenazine) deplete dopamine and reduce chorea |
| Sydenham chorea | Post-streptococcal molecular mimicry; antibodies cross-react with basal ganglia antigens, causing inflammation and neuronal dysfunction | Immunomodulatory therapy may accelerate recovery; penicillin prophylaxis prevents recurrence |
| Subthalamic nucleus stroke | Destruction of subthalamic nucleus removes excitatory input to globus pallidus internus, causing severe contralateral hemiballismus-hemichorea | Often improves spontaneously; dopamine blockers for severe cases |
| Hyperglycemic chorea | Non-ketotic hyperglycemia causes striatal dysfunction through hyperviscosity, altered metabolism, and petechial hemorrhage; CT/MRI shows striatal hyperintensity | Correction of hyperglycemia typically resolves chorea within days to weeks |
| Tardive dyskinesia | Chronic dopamine receptor blockade causes D2 receptor upregulation and hypersensitivity; leads to orofacial-predominant choreiform movements | Discontinue offending agent if possible; VMAT2 inhibitors are first-line treatment |
| Anti-NMDA receptor encephalitis | Antibodies against NMDA receptor NR1 subunit cause receptor internalization, leading to NMDA hypofunction with relative dopaminergic excess | Immunotherapy (steroids, IVIG, plasmapheresis, rituximab); tumor removal if paraneoplastic |
| Wilson disease | Copper accumulation in basal ganglia (especially putamen) causes neuronal toxicity and degeneration; mixed movement disorder with dystonia often predominant | Copper chelation (penicillamine, trientine) and zinc can halt progression if treated early |
| Levodopa-induced dyskinesia | Pulsatile dopamine stimulation in denervated striatum causes abnormal plasticity and sensitization; peak-dose chorea reflects excessive dopaminergic drive | Reduce levodopa dose; add amantadine; consider continuous dopaminergic stimulation |
Why Chorea Appears Random and Flowing
The seemingly random, flowing nature of choreiform movements reflects the widespread and fluctuating disinhibition of motor cortex regions. Unlike tremor (which involves rhythmic oscillation in a single motor circuit) or dystonia (which involves sustained co-contraction), chorea results from brief, sequential activation of different motor programs without normal inhibitory control. This produces movements that “migrate” from one body part to another, appearing dance-like or fidgety.
Often Overlooked Mechanism: Hyperglycemia
Non-ketotic hyperglycemia is one of the most common causes of acute hemichorea-hemiballismus in elderly patients, yet it is frequently missed. The mechanism involves striatal petechial hemorrhage and metabolic dysfunction, producing characteristic T1-hyperintense signal in the contralateral striatum on MRI. Unlike most other causes, hyperglycemic chorea is fully reversible with glucose correction—making it a “cannot miss” diagnosis. Always check blood glucose in any patient presenting with acute-onset unilateral chorea.
Anatomical Lesion Correlations
| Lesion Location | Movement Pattern | Common Causes |
|---|---|---|
| Striatum (caudate/putamen) | Contralateral hemichorea; generalized if bilateral | Huntington disease, stroke, hyperglycemia, autoimmune |
| Subthalamic nucleus | Severe contralateral hemiballismus (most violent form of chorea) | Small lacunar stroke (classic), hemorrhage, tumor |
| Globus pallidus externus | Contralateral chorea (mimics subthalamic lesion effect) | Stroke, hypoxia, carbon monoxide poisoning |
| Thalamus | Contralateral chorea/athetosis; may have sensory symptoms | Stroke, tumor, multiple sclerosis |
3. History Taking
A comprehensive approach to eliciting the Chorea history
Red Flags — Require Urgent Evaluation
- Acute onset with fever — Infectious or autoimmune encephalitis
- Altered consciousness or confusion — Encephalitis, metabolic emergency, Creutzfeldt-Jakob disease
- Sudden-onset hemichorea in elderly — Stroke or hyperglycemic emergency
- Recent pharyngitis in young patient — Sydenham chorea (rheumatic fever)
- Pregnancy or postpartum — Chorea gravidarum (may indicate antiphospholipid syndrome)
- Rapid cognitive decline — Creutzfeldt-Jakob disease, autoimmune encephalitis
- New psychiatric symptoms with chorea — Huntington disease, anti-NMDA receptor encephalitis, Wilson disease
- Weight loss or known malignancy — Paraneoplastic syndrome
- Young patient under 50 with liver disease — Wilson disease (requires urgent evaluation)
- Self-mutilating behavior — Lesch-Nyhan syndrome, neuroacanthocytosis
Systematic History: The “CHOREA” Approach
Use the mnemonic “CHOREA” to ensure comprehensive history taking:
- C — Character and Course: What do the movements look like? When did they start? Are they getting worse, stable, or improving? Acute, subacute, or chronic onset?
- H — Hereditary and Family History: Any family members with similar movements, dementia, psychiatric illness, or early death? Consanguinity? Ethnic background?
- O — Other Movements and Symptoms: Are there other movement abnormalities (dystonia, parkinsonism, tics, myoclonus)? Cognitive changes? Psychiatric symptoms? Swallowing or speech difficulties?
- R — Risk Factors and Exposures: Medications (especially neuroleptics, dopaminergics, stimulants)? Recreational drugs? Recent infections? Vascular risk factors? HIV risk?
- E — Exacerbating and Relieving Factors: Worse with stress or fatigue? Better with sleep or relaxation? Can movements be suppressed voluntarily?
- A — Associated Conditions: Diabetes? Thyroid disease? Autoimmune disorders (lupus, antiphospholipid syndrome)? Pregnancy? Liver or kidney disease?
Targeted Questions by Suspected Cause
| Suspected Cause | Key Features | Ask This Question |
|---|---|---|
| Huntington disease | Family history, cognitive decline, psychiatric symptoms, progressive course | “Has anyone in your family had similar movements, dementia, or been in a psychiatric hospital? Did any relatives die young or have unexplained neurological problems?” |
| Tardive dyskinesia | Neuroleptic exposure, orofacial predominance, chronic course | “Have you ever taken medications for psychiatric conditions, nausea, or stomach problems? For how long? This includes metoclopramide and prochlorperazine.” |
| Sydenham chorea | Young patient, recent sore throat, carditis history | “Did you have a severe sore throat or skin infection in the past few months? Any history of rheumatic fever or heart problems?” |
| Wilson disease | Young onset (under 50), liver disease, psychiatric features, dystonia | “Have you ever had liver problems or jaundice? Any psychiatric symptoms before the movements started? Do you have siblings with liver or neurological disease?” |
| Hyperglycemic chorea | Elderly, diabetes, acute hemichorea | “Do you have diabetes? Have you been checking your blood sugars? Any recent illness, infection, or change in medications?” |
| Vascular chorea | Sudden onset, unilateral, vascular risk factors | “Did the movements come on suddenly—can you tell me exactly what you were doing when they started? Do you have high blood pressure, diabetes, or heart problems?” |
| Autoimmune encephalitis | Subacute onset, psychiatric symptoms, seizures, autonomic instability | “Have you had any personality changes, confusion, memory problems, or seizures? Any recent viral illness? For women: any ovarian problems or pelvic pain?” |
| Systemic lupus erythematosus | Young woman, multisystem involvement, photosensitivity | “Have you had joint pains, skin rashes, mouth ulcers, or kidney problems? Any history of blood clots or miscarriages?” |
| Neuroacanthocytosis | Orofacial chorea, lip and tongue biting, seizures, myopathy | “Do you bite your lips or tongue frequently? Have you had seizures? Any difficulty swallowing or changes in your voice? Muscle weakness?” |
| Drug-induced (non-tardive) | Temporal relationship to medication, reversible | “Have you started any new medications recently—including over-the-counter drugs, herbal supplements, or recreational substances? Stimulants? Cocaine or amphetamines?” |
Characterizing Onset and Progression
| Onset Pattern | Typical Causes | Key History Points |
|---|---|---|
| Hyperacute (minutes to hours) | Stroke, drug intoxication | Exact time of onset; what patient was doing; associated symptoms (weakness, sensory changes) |
| Acute (hours to days) | Metabolic (hyperglycemia), drug reaction, stroke | Recent medication changes; glucose control; vascular risk factors |
| Subacute (weeks to months) | Autoimmune, paraneoplastic, Sydenham chorea, HIV | Recent infections; constitutional symptoms; psychiatric prodrome; malignancy risk |
| Chronic progressive (months to years) | Huntington disease, other neurodegenerative causes | Family history; cognitive and psychiatric timeline; functional decline |
| Chronic stable or slowly progressive | Tardive dyskinesia, benign hereditary chorea, post-stroke | Duration of neuroleptic exposure; childhood onset; prior stroke |
Medication and Substance History
Medications That Cause Chorea
- Dopamine receptor blockers (tardive): Haloperidol, risperidone, olanzapine, metoclopramide, prochlorperazine — onset after months to years of use
- Dopaminergic agents: Levodopa, dopamine agonists, amantadine — typically dose-related and reversible
- Stimulants: Amphetamines, methylphenidate, cocaine — acute onset, dose-related
- Anticonvulsants: Phenytoin, carbamazepine, gabapentin, valproate — usually with toxicity or high levels
- Oral contraceptives: May unmask chorea in predisposed individuals (history of Sydenham chorea)
- Lithium: Usually with toxicity; may persist after discontinuation
- Antihistamines: Diphenhydramine, especially in elderly
- Calcium channel blockers: Cinnarizine, flunarizine (common in some countries)
Social and Exposure History
- Alcohol: Chronic alcoholism (nutritional deficiency, hepatic encephalopathy); acute intoxication rarely causes chorea
- Recreational drugs: Cocaine, amphetamines, ecstasy can cause acute chorea
- Occupational exposures: Manganese (welders, miners), carbon monoxide, organic solvents
- HIV risk factors: HIV-associated chorea can occur at any stage; ask about sexual history, IV drug use
- Travel history: Relevant for infectious causes in endemic areas
- Pregnancy: Chorea gravidarum; may be first presentation of antiphospholipid syndrome or SLE
- Family history: Detailed three-generation pedigree; ask specifically about dementia, psychiatric hospitalizations, suicide, early death
Critical Associated Symptoms to Elicit
| Symptom Category | Specific Symptoms | Diagnostic Significance |
|---|---|---|
| Cognitive | Memory loss, executive dysfunction, slowed thinking, poor concentration | Huntington disease, Wilson disease, autoimmune encephalitis, Creutzfeldt-Jakob disease |
| Psychiatric | Depression, irritability, apathy, psychosis, personality change, obsessive-compulsive behaviors | Huntington disease (often precedes chorea), Wilson disease, anti-NMDA receptor encephalitis |
| Other movements | Dystonia, parkinsonism, tics, myoclonus, ataxia | Wilson disease (dystonia prominent), neuroacanthocytosis (tics, dystonia), Huntington disease-like syndromes |
| Bulbar | Dysarthria, dysphagia, drooling, tongue protrusion | Neuroacanthocytosis, advanced Huntington disease, Wilson disease |
| Seizures | Generalized or focal seizures | Anti-NMDA receptor encephalitis, neuroacanthocytosis, mitochondrial disease |
| Autonomic | Blood pressure instability, hyperthermia, diaphoresis, urinary symptoms | Autoimmune encephalitis, advanced neurodegenerative disease |
| Systemic | Fever, weight loss, rash, joint pain, liver dysfunction | Autoimmune (SLE), paraneoplastic, infectious, Wilson disease |
Taking a Meaningful Family History
A negative family history does not exclude Huntington disease. Up to 8% of cases appear “sporadic” due to:
- Non-paternity: The biological father may be unknown
- Early parental death: Affected parent died before symptom onset
- Intermediate alleles: CAG repeats in the 27-35 range can expand in subsequent generations
- Misdiagnosis: Affected relatives diagnosed with “dementia,” “psychiatric illness,” or “Parkinson’s disease”
- Family secrets: Institutionalization or suicide may not be discussed openly
Ask specifically: “Did anyone in your family ever have problems with walking, strange movements, memory loss, depression, or end up in a nursing home or psychiatric facility at a young age?”
4. Physical Examination
A systematic approach for evaluating patients with Chorea
Systematic Framework: Use the “Observation, General, Neurological, Systemic” approach for complete examination of patients presenting with chorea. Begin by observing the patient before formal examination—choreiform movements are often most apparent when the patient is unaware of being watched.
Initial Observation and General Inspection
- Observe during history-taking: Chorea is often more prominent when the patient is distracted; note distribution, frequency, and amplitude of movements
- Parakinesia: Watch for incorporation of involuntary movements into seemingly purposeful actions (e.g., smoothing hair, adjusting clothing)
- Motor impersistence: Ask patient to protrude tongue and hold it out—”serpentine” or “trombone” tongue is characteristic
- Facial appearance: Grimacing, eyebrow elevation, lip movements; “piano-playing” fingers at rest
- Gait observation: Dancing or lurching quality; wide-based; may appear intoxicated
- Speech: Irregular rate and rhythm; explosive quality; dysarthria
- Body habitus: Weight loss may suggest Huntington disease or malignancy; obesity relevant for metabolic causes
- Self-injury: Lip or tongue wounds suggest neuroacanthocytosis
Vital Signs
| Vital Sign | What to Look For | Clinical Significance |
|---|---|---|
| Temperature | Fever or hypothermia | Fever suggests infection or autoimmune encephalitis; hypothermia may occur with hypothyroidism |
| Heart Rate | Tachycardia, irregular rhythm | Tachycardia with thyrotoxicosis; arrhythmia may suggest autonomic instability or carditis (Sydenham) |
| Blood Pressure | Hypertension, hypotension, orthostatic changes | Hypertension as vascular risk factor; labile blood pressure in autoimmune encephalitis |
| Respiratory Rate | Irregular breathing pattern | Respiratory dysrhythmia in autoimmune encephalitis; Kussmaul breathing with hyperglycemia |
| Oxygen Saturation | Hypoxia | May indicate aspiration risk in severe chorea with dysphagia |
| Blood Glucose | Hyperglycemia | Point-of-care glucose essential in acute hemichorea; non-ketotic hyperglycemia is reversible cause |
Characterizing the Movement Disorder
| Feature to Assess | How to Test | What to Document |
|---|---|---|
| Distribution | Observe all body regions; compare sides | Generalized vs. hemichorea vs. focal; proximal vs. distal; face, trunk, limbs |
| Amplitude | Observe range of movement | Small (choreiform) vs. large (ballistic); helps grade severity |
| Frequency | Count movements over 30-60 seconds | Continuous vs. intermittent; helps monitor treatment response |
| Motor impersistence | Tongue protrusion, sustained grip (“milkmaid’s grip”), eyelid closure | Inability to maintain sustained contraction; highly characteristic of chorea |
| Effect of action | Observe during reaching, writing, walking | Chorea typically worsens with voluntary movement |
| Effect of distraction | Engage patient in conversation or mental tasks | Chorea often increases with distraction (unlike functional movements) |
| Suppressibility | Ask patient to try to hold still | Brief voluntary suppression possible but movements re-emerge; helps distinguish from tics |
Neurological Examination
Cranial Nerves
- Eye movements: Slow saccades, difficulty initiating saccades, increased latency (Huntington disease); opsoclonus (autoimmune); nystagmus (drug toxicity, Wernicke)
- Kayser-Fleischer rings: Slit-lamp examination essential if Wilson disease suspected—brownish-green corneal ring; may be visible to naked eye in severe cases
- Facial movements: Choreiform grimacing; note symmetry; facial dystonia
- Tongue: Protrude and observe; serpentine/trombone movement; lip and tongue biting scars (neuroacanthocytosis); tongue dystonia
- Speech assessment: Dysarthria character (hyperkinetic—irregular, explosive); palilalia; observe respiratory coordination
- Swallowing: Bedside swallow assessment; coughing or choking with liquids suggests aspiration risk
Motor Examination
- Tone: May be reduced (hypotonia) in chorea; “hung-up” reflexes; increased tone suggests concurrent dystonia or parkinsonism
- Power: Apparent weakness may be due to motor impersistence; true weakness suggests neuroacanthocytosis or myopathy
- Reflexes: Often “pendular” (hypotonic); asymmetry suggests structural lesion
- Coordination: Difficult to assess due to chorea; ataxia suggests spinocerebellar ataxia or Huntington disease-like syndrome
- Associated movements: Note concurrent dystonia (Wilson disease), parkinsonism (advanced Huntington disease), or tics (neuroacanthocytosis)
Gait Assessment
- Observation: “Dancing” or lurching quality; irregular cadence; lateral deviations
- Tandem gait: Usually impaired in chorea
- Arm swing: May be excessive or asymmetric
- Turns: Often unsteady; may require multiple steps
- Motor impersistence in stance: Difficulty maintaining posture; knee buckling
Cognitive and Psychiatric Assessment
| Domain | How to Test | Abnormalities Suggesting |
|---|---|---|
| Attention/Concentration | Serial 7s, digit span, months backward | Early Huntington disease, autoimmune encephalitis |
| Executive function | Luria sequence, verbal fluency, clock drawing | Huntington disease (frontal-subcortical pattern) |
| Memory | 3-word recall, delayed recall | Retrieval deficits (subcortical); encoding deficits suggest cortical involvement |
| Processing speed | Timed tasks, Symbol-Digit Modalities | Huntington disease; often earliest cognitive change |
| Psychiatric features | Screen for depression, anxiety, irritability, apathy, psychosis | Depression common in Huntington disease; psychosis in anti-NMDA receptor encephalitis |
Systemic Examination
Integumentary
- Skin rashes: Malar rash, discoid lesions (systemic lupus erythematosus); livedo reticularis (antiphospholipid syndrome)
- Jaundice: Wilson disease, hepatic encephalopathy
- Telangiectasia: Ataxia-telangiectasia
- Injection sites: HIV risk, drug use
Cardiovascular
- Heart murmurs: Mitral regurgitation or stenosis in rheumatic heart disease (Sydenham chorea)
- Cardiomegaly: Rheumatic carditis, dilated cardiomyopathy (neuroacanthocytosis)
- Signs of heart failure: McLeod syndrome, advanced disease
Abdominal
- Hepatomegaly or splenomegaly: Wilson disease, storage disorders
- Ascites: Hepatic Wilson disease, cirrhosis
- Abdominal masses: Ovarian teratoma (anti-NMDA receptor encephalitis)
Musculoskeletal
- Muscle wasting: Neuroacanthocytosis, advanced Huntington disease
- Arthritis: Systemic lupus erythematosus, rheumatic fever
- Contractures: Advanced or juvenile-onset disease
Specific Clinical Signs and Their Significance
| Sign | How to Elicit | Conditions |
|---|---|---|
| Milkmaid’s grip | Ask patient to sustain grip on examiner’s fingers; note rhythmic fluctuations | Motor impersistence; characteristic of Huntington disease and other choreiform disorders |
| Serpentine/trombone tongue | Ask patient to protrude tongue and hold steady | Motor impersistence; typical of Huntington disease |
| Hung-up reflexes | Elicit knee jerk; observe prolonged swing before settling | Hypotonia associated with chorea; also seen in hypothyroidism |
| Kayser-Fleischer rings | Slit-lamp examination (may be visible grossly in severe cases) | Wilson disease—present in nearly all patients with neurological involvement |
| Lip and tongue biting | Inspect oral cavity for scars, ulcerations, missing tissue | Neuroacanthocytosis (self-mutilating; feeding dystonia); Lesch-Nyhan syndrome |
| Rubber man phenomenon | Patient appears to collapse into chair; hypotonic limbs | Severe hypotonia in chorea |
| Slow saccades | Ask patient to look rapidly between two targets; observe velocity | Huntington disease; spinocerebellar ataxias; progressive supranuclear palsy |
Expected Findings by Etiology
| Condition | Movement Pattern | Neurological Features | Systemic Features |
|---|---|---|---|
| Huntington disease | Generalized chorea; later dystonia and parkinsonism | Slow saccades, motor impersistence, cognitive decline (executive > memory) | Weight loss; psychiatric features often prominent |
| Wilson disease | Mixed: dystonia often predominant; may have chorea, tremor, parkinsonism | Kayser-Fleischer rings, dysarthria, drooling, “risus sardonicus” | Hepatomegaly, jaundice, splenomegaly; psychiatric symptoms |
| Sydenham chorea | Generalized chorea, often asymmetric; hypotonia | Motor impersistence, emotional lability; usually no cognitive deficit | Carditis (murmurs), arthritis, erythema marginatum (rheumatic fever) |
| Tardive dyskinesia | Orofacial predominant (tongue, lips, jaw); may be generalized | Usually no other neurological signs unless comorbid parkinsonism | History of chronic neuroleptic use |
| Hyperglycemic chorea | Hemichorea-hemiballismus; unilateral | Typically isolated movement disorder; no other focal signs | Signs of dehydration; diabetic complications |
| Anti-NMDA receptor encephalitis | Chorea, orofacial dyskinesias, dystonia | Psychiatric symptoms, seizures, autonomic instability, decreased consciousness | Ovarian teratoma may be palpable; fever |
| Neuroacanthocytosis | Orofacial chorea with feeding dystonia; limb chorea | Lip/tongue biting, seizures, areflexia, peripheral neuropathy | Muscle wasting, elevated creatine kinase |
| Systemic lupus erythematosus | Usually generalized chorea | May have other CNS manifestations (stroke, seizures) | Malar rash, arthritis, serositis, oral ulcers |
Important Teaching Point
The examination findings may be minimal beyond the chorea itself. Many causes of chorea—including drug-induced chorea, early Huntington disease, metabolic causes, and autoimmune conditions—may present with chorea as the only or predominant finding. The absence of other neurological or systemic signs does not exclude serious underlying pathology. A comprehensive history and targeted investigations are essential regardless of examination findings.
Quantifying Severity: Unified Huntington’s Disease Rating Scale – Total Motor Score
While formal rating scales exist, a practical bedside assessment should document:
Severity Indicators
- Frequency of movements (intermittent vs. continuous)
- Amplitude (mild, moderate, severe)
- Distribution (focal, hemibody, generalized)
- Functional impact (eating, dressing, walking)
Functional Assessment
- Can patient feed themselves safely?
- Is ambulation independent?
- Can patient perform activities of daily living?
- Is there aspiration risk?
5. Differential Diagnosis
Systematic approach organized by probability, duration, and clinical features
The differential diagnosis of chorea is broad, ranging from common drug-induced causes to rare genetic disorders. A systematic approach based on onset pattern, age, and associated features allows efficient narrowing of possibilities. The priority is always to identify treatable and reversible causes before considering neurodegenerative conditions.
Acute Chorea (Onset within days)
| Probability | Condition | Key Features | Red Flags |
|---|---|---|---|
| COMMON | Drug-induced chorea (non-tardive) | Recent medication change; temporal relationship; reversible on discontinuation | Concurrent serotonin syndrome signs; neuroleptic malignant syndrome |
| COMMON | Non-ketotic hyperglycemic chorea | Elderly diabetic; hemichorea-hemiballismus; glucose often greater than 400 mg/dL | Altered consciousness; severe dehydration |
| LESS COMMON | Vascular chorea (stroke) | Sudden onset; hemichorea; vascular risk factors; contralateral basal ganglia lesion | Other focal deficits; altered consciousness |
| LESS COMMON | Stimulant intoxication | Cocaine, amphetamines; acute onset; sympathomimetic signs; psychiatric symptoms | Hyperthermia; seizures; cardiovascular instability |
| UNCOMMON BUT SERIOUS | Autoimmune encephalitis | Subacute psychiatric prodrome; seizures; autonomic instability; young women | Decreased consciousness; respiratory failure; status epilepticus |
| UNCOMMON BUT SERIOUS | Cerebral venous thrombosis | Headache; seizures; focal deficits; hypercoagulable states; postpartum | Severe headache; papilledema; altered consciousness |
Subacute Chorea (Onset over weeks to months)
Clinical Approach to Subacute Chorea:
- Step 1: Exclude drug exposure — Review all medications including over-the-counter and herbal
- Step 2: Check for metabolic and systemic causes — Glucose, thyroid, liver function, pregnancy test
- Step 3: Consider autoimmune and paraneoplastic — Particularly in young patients or with psychiatric features
- Step 4: Evaluate for infectious causes — HIV testing in all patients; consider other infections based on risk
| Probability | Condition | Key Features | Expected Course |
|---|---|---|---|
| COMMON | Sydenham chorea | Children and adolescents; post-streptococcal; emotional lability; hypotonia | Self-limited over months; may recur; risk of carditis |
| COMMON | Tardive dyskinesia (early recognition) | Chronic neuroleptic use; orofacial predominant; may worsen initially after drug cessation | May persist indefinitely; partial improvement possible |
| LESS COMMON | Anti-NMDA receptor encephalitis | Young women; psychiatric prodrome; orofacial dyskinesias; seizures; autonomic instability | Progressive without treatment; good recovery with immunotherapy if early |
| LESS COMMON | Systemic lupus erythematosus chorea | Young women; other SLE features; antiphospholipid antibodies often present | May be episodic; responds to immunosuppression |
| LESS COMMON | HIV-associated chorea | May occur at any CD4 count; opportunistic infections; direct HIV effect | May improve with antiretroviral therapy |
| UNCOMMON BUT SERIOUS | Paraneoplastic chorea | Anti-CV2/CRMP5, anti-Hu antibodies; associated malignancy (lung, breast, ovarian) | May stabilize or improve with tumor treatment |
| UNCOMMON BUT SERIOUS | Creutzfeldt-Jakob disease | Rapid cognitive decline; myoclonus; ataxia; characteristic EEG and MRI | Rapidly progressive; fatal within months |
Chronic Chorea (Present for more than 6 months)
Step-by-Step Approach to Chronic Chorea:
- Step 1: Rule out Wilson disease in ALL patients under 50 years — This is treatable and must not be missed
- Step 2: Assess for tardive dyskinesia — Document neuroleptic exposure history carefully
- Step 3: Evaluate family history — Three-generation pedigree for Huntington disease and other hereditary causes
- Step 4: Consider Huntington disease testing if family history positive or suggestive clinical picture
- Step 5: If Huntington disease negative, pursue Huntington disease-like syndrome panel and other genetic causes
| Probability | Condition | Approximate Frequency | Key Distinguishing Features |
|---|---|---|---|
| COMMON | Huntington disease | Most common hereditary cause; 5-10 per 100,000 in European populations | Autosomal dominant; CAG repeat expansion; cognitive decline; psychiatric features; positive family history (usually) |
| COMMON | Tardive dyskinesia | 20-30% of chronically treated patients with neuroleptics | Orofacial predominant; history of dopamine receptor blocker use; may persist after drug cessation |
| LESS COMMON | Senile chorea | Elderly patients; diagnosis of exclusion | Late onset; mild; non-progressive or slowly progressive; no family history; normal imaging |
| LESS COMMON | Wilson disease | 1 in 30,000; must exclude in all patients under 50 | Mixed movement disorder (dystonia often predominant); Kayser-Fleischer rings; liver disease; psychiatric features |
| UNCOMMON | Huntington disease-like syndromes (HDL1-4) | Rare; consider when HD genetic test negative | Phenotypically similar to HD; different genetic causes; autosomal dominant or recessive |
| UNCOMMON | Neuroacanthocytosis (chorea-acanthocytosis) | Rare; autosomal recessive | Orofacial chorea with lip/tongue biting; feeding dystonia; seizures; elevated creatine kinase; acanthocytes |
| UNCOMMON | McLeod syndrome | Rare; X-linked | Males; cardiomyopathy; elevated creatine kinase; acanthocytes; Kell blood group abnormality |
| UNCOMMON | Spinocerebellar ataxias (especially SCA17) | Rare | Ataxia prominent; may have chorea, dystonia, parkinsonism; cognitive decline |
| UNCOMMON | Benign hereditary chorea | Rare; NKX2-1 mutations | Childhood onset; non-progressive; thyroid abnormalities; pulmonary problems (brain-thyroid-lung syndrome) |
| UNCOMMON | Dentatorubral-pallidoluysian atrophy | More common in Japan; rare elsewhere | Ataxia, chorea, myoclonus, epilepsy, dementia; CAG repeat expansion in ATN1 gene |
Anatomical Approach to Chorea
Hereditary / Genetic
Huntington disease
HD-like syndromes (HDL1-4)
Wilson disease
Neuroacanthocytosis
McLeod syndrome
Benign hereditary chorea
Spinocerebellar ataxias
DRPLA
Mitochondrial disorders
Autoimmune / Inflammatory
Sydenham chorea
Anti-NMDA receptor encephalitis
Systemic lupus erythematosus
Antiphospholipid syndrome
Paraneoplastic syndromes
Multiple sclerosis (rare)
Post-infectious (other)
Celiac disease
Drug-Induced / Toxic
Tardive dyskinesia
Levodopa-induced
Stimulants (cocaine, amphetamines)
Anticonvulsants
Oral contraceptives
Lithium toxicity
Carbon monoxide
Manganese toxicity
Alcohol withdrawal
Structural / Metabolic
Stroke (subthalamic, striatal)
Non-ketotic hyperglycemia
Hyperthyroidism
Hypoparathyroidism
Hepatic encephalopathy
Polycythemia vera
Brain tumor
Hypoxic injury
HIV/AIDS
Drug-Induced Chorea
| Drug or Drug Class | Mechanism | Characteristics | Time to Resolution After Stopping |
|---|---|---|---|
| Dopamine receptor blockers (neuroleptics) | D2 receptor upregulation and hypersensitivity after chronic blockade | Tardive; orofacial predominant; may worsen initially on withdrawal | Months to years; may be permanent |
| Metoclopramide, prochlorperazine | Same as neuroleptics (D2 blockade) | Often overlooked; used for nausea/gastroparesis; tardive dyskinesia risk | Months to years; may be permanent |
| Levodopa | Excessive dopaminergic stimulation in sensitized striatum | Peak-dose chorea; wearing-off dyskinesias; dose-related | Hours to days after dose reduction |
| Dopamine agonists | Direct dopamine receptor stimulation | Similar to levodopa; may be more sustained | Days after discontinuation |
| Stimulants (amphetamines, methylphenidate) | Increased dopamine release | Acute chorea; dose-related; associated with psychiatric symptoms | Hours to days |
| Cocaine | Dopamine reuptake inhibition | Acute onset; often called “crack dancing”; may be generalized or focal | Hours to days |
| Phenytoin | Uncertain; possibly GABAergic or cerebellar | Usually with toxicity; may be focal or generalized | Days to weeks after correction |
| Carbamazepine | Similar to phenytoin | Dose-related; rare | Days after dose reduction |
| Oral contraceptives | Estrogen effect on dopamine sensitivity | May unmask chorea in predisposed (prior Sydenham); chorea gravidarum | Weeks to months after discontinuation |
| Lithium | Multiple mechanisms; often with toxicity | Usually generalized; associated with other signs of toxicity | Days to weeks; may persist |
| Digoxin | Uncertain | Rare; usually with toxicity | Days after correction |
| Antihistamines (diphenhydramine) | Anticholinergic effect altering dopamine-acetylcholine balance | More common in elderly; may worsen tardive dyskinesia | Days after discontinuation |
Age-Based Diagnostic Priorities
| Age Group | First Consider | Must Not Miss | Key Investigations |
|---|---|---|---|
| Young adult (18-40) | Drug-induced, Sydenham, autoimmune, Wilson disease | Wilson disease (treatable); anti-NMDA receptor encephalitis | Ceruloplasmin, 24-hour urine copper, slit-lamp; autoimmune panel; brain MRI |
| Middle age (40-60) | Huntington disease, tardive dyskinesia, vascular | Huntington disease (genetic counseling implications); Wilson disease (if under 50) | HTT gene testing (with counseling); Wilson workup if under 50; brain MRI |
| Elderly (over 60) | Tardive dyskinesia, hyperglycemic, vascular, senile chorea | Hyperglycemia (reversible); stroke; paraneoplastic syndrome | Glucose; brain MRI; malignancy workup if warranted |
Quick Reference: “If You See This, Think This”
| Clinical Clue | Think This First | Next Step |
|---|---|---|
| Elderly + diabetes + acute hemichorea | Non-ketotic hyperglycemic chorea | Check glucose immediately; brain MRI (T1 hyperintense striatum) |
| Chronic neuroleptic use + orofacial movements | Tardive dyskinesia | Document exposure; consider VMAT2 inhibitor |
| Family history of dementia/chorea + cognitive decline | Huntington disease | Genetic counseling; HTT gene testing |
| Young patient + liver abnormalities + movement disorder | Wilson disease | Ceruloplasmin, slit-lamp examination, 24-hour urine copper |
| Young woman + psychiatric symptoms + seizures | Anti-NMDA receptor encephalitis | CSF analysis; anti-NMDA receptor antibodies; pelvic imaging for teratoma |
| Post-streptococcal infection + child/adolescent | Sydenham chorea | ASO titer; anti-DNase B; echocardiogram |
| Lip/tongue biting + orofacial dystonia + seizures | Neuroacanthocytosis | Blood smear for acanthocytes; creatine kinase; VPS13A gene testing |
| Sudden onset + vascular risk factors + hemichorea | Stroke (subthalamic or striatal) | Urgent brain MRI with DWI; vascular workup |
| Chorea + rash + joint pain + young woman | Systemic lupus erythematosus | ANA, anti-dsDNA, antiphospholipid antibodies; complement levels |
| Rapid cognitive decline + myoclonus + chorea | Creutzfeldt-Jakob disease | Brain MRI (DWI cortical ribboning); EEG; CSF 14-3-3 and RT-QuIC |
| Pregnancy or postpartum + new chorea | Chorea gravidarum; antiphospholipid syndrome | Antiphospholipid antibodies; lupus anticoagulant; prior Sydenham history |
6. Diagnostic Investigations
A stepwise, cost-effective approach guided by clinical suspicion
The investigation of chorea should be systematic and guided by clinical features. All patients require baseline screening to exclude common treatable causes, followed by targeted investigations based on the clinical picture. The priority is identifying reversible causes before pursuing genetic testing for neurodegenerative conditions.
Baseline Investigations for All Patients with Chorea
| Investigation | Purpose | What to Look For | Practical Points |
|---|---|---|---|
| Complete blood count with peripheral smear | Screen for acanthocytosis; polycythemia; infection | Acanthocytes (neuroacanthocytosis, McLeod); elevated hematocrit; leukocytosis | Request fresh wet preparation for acanthocytes; may need repeated samples |
| Comprehensive metabolic panel | Metabolic and hepatic causes | Glucose (hyperglycemia); liver enzymes (Wilson, hepatic encephalopathy); electrolytes | Point-of-care glucose essential in acute hemichorea |
| Thyroid function tests | Thyrotoxicosis can cause chorea | Suppressed TSH with elevated T4/T3 | Chorea resolves with treatment of hyperthyroidism |
| Erythrocyte sedimentation rate and C-reactive protein | Inflammatory or autoimmune causes | Elevation suggests inflammatory process | May be normal in some autoimmune conditions |
| Antinuclear antibody | Screen for systemic lupus erythematosus | Positive ANA; requires confirmation with specific antibodies | Low specificity; positive result requires further workup |
| HIV testing | HIV-associated chorea | HIV antibody/antigen; viral load if positive | Offer to all patients; chorea can occur at any disease stage |
| Brain MRI with and without contrast | Structural lesions; characteristic patterns | Caudate atrophy (Huntington); T1 striatal hyperintensity (hyperglycemia); stroke; inflammation | Include DWI, FLAIR, T1, T2, and post-contrast sequences |
Wilson Disease Workup — Mandatory in All Patients Under 50 Years
Do Not Miss Wilson Disease
Wilson disease is one of the few treatable causes of progressive neurological decline. It must be excluded in ALL patients under 50 years presenting with chorea (or any movement disorder). Early treatment can prevent irreversible neurological damage.
| Test | Expected Finding in Wilson Disease | Sensitivity/Specificity | Caveats |
|---|---|---|---|
| Serum ceruloplasmin | Low (typically less than 20 mg/dL) | Sensitivity approximately 85%; low specificity | Can be low in other conditions; may be normal in 5-15% of Wilson disease |
| 24-hour urine copper | Elevated (greater than 100 mcg/24 hours; often greater than 40 mcg/24 hours is suspicious) | Highly sensitive when properly collected | Requires proper collection; avoid copper contamination |
| Slit-lamp examination | Kayser-Fleischer rings (copper deposits in Descemet membrane) | Present in approximately 95% with neurological Wilson disease | Must be performed by experienced ophthalmologist; may be absent in hepatic-only disease |
| Serum copper | Total copper low; free copper elevated | Helpful adjunct | Free copper = total copper – (ceruloplasmin × 3) |
| Liver biopsy copper content | Greater than 250 mcg/g dry weight | Gold standard | Invasive; reserved for unclear cases |
| ATP7B genetic testing | Biallelic pathogenic variants | Confirms diagnosis | Over 500 mutations known; may miss some variants |
Targeted Investigations by Suspected Etiology
If Suspecting Huntington Disease
Pre-Test Requirements
- Genetic counseling: Mandatory before testing; discuss implications for patient and family
- Informed consent: Patient must understand irreversible nature of positive result
- Psychological assessment: Ensure patient has adequate support
- Consider predictive vs. diagnostic testing: Different protocols for symptomatic vs. at-risk individuals
Test Interpretation
- HTT gene CAG repeat analysis: Diagnostic test
- Less than 27 repeats: Normal
- 27-35 repeats: Intermediate; may expand in offspring
- 36-39 repeats: Reduced penetrance; may or may not develop disease
- 40 or more repeats: Full penetrance; will develop disease if patient lives long enough
If Suspecting Autoimmune or Paraneoplastic Chorea
Autoimmune Panel
- Anti-NMDA receptor antibodies: Serum and CSF (CSF more sensitive)
- Antiphospholipid antibodies: Lupus anticoagulant, anticardiolipin, anti-β2 glycoprotein I
- Anti-dsDNA, complement levels: If SLE suspected
- Anti-streptolysin O (ASO), anti-DNase B: Sydenham chorea
Paraneoplastic Panel
- Anti-CV2/CRMP5 antibodies: Associated with lung cancer, thymoma
- Anti-Hu (ANNA-1): Small cell lung cancer
- Anti-Yo (PCA-1): Ovarian, breast cancer
- CT chest/abdomen/pelvis: Malignancy screening
- PET-CT: If high suspicion and CT negative
- Pelvic ultrasound or MRI: Ovarian teratoma (anti-NMDA receptor encephalitis)
If Suspecting Neuroacanthocytosis Syndromes
First-Line Tests
- Peripheral blood smear: Fresh wet preparation for acanthocytes (greater than 3% suggestive); may need multiple samples
- Creatine kinase: Typically elevated (500-3000 U/L) in chorea-acanthocytosis
- Liver function tests: May show mild elevations
Second-Line Tests
- Kell blood group typing: Absent Kx antigen in McLeod syndrome
- VPS13A gene testing: Chorea-acanthocytosis (autosomal recessive)
- XK gene testing: McLeod syndrome (X-linked)
- Echocardiogram: Cardiomyopathy screening (especially McLeod)
If Suspecting Vascular Chorea
Acute Imaging
- Brain MRI with DWI: Acute stroke; subthalamic or striatal infarct
- MR or CT angiography: Vascular occlusion; vasculitis
- CT head: If MRI not immediately available; hemorrhage
Vascular Workup
- Lipid panel, HbA1c: Vascular risk factors
- ECG, echocardiogram: Cardioembolic source
- Carotid ultrasound: Large vessel disease
- Hypercoagulable workup: If young or recurrent events
Cerebrospinal Fluid Analysis
When to Perform Lumbar Puncture
CSF analysis is indicated when autoimmune, infectious, or inflammatory etiologies are suspected. It is particularly important in:
- Subacute onset with psychiatric features or altered consciousness
- Suspected autoimmune encephalitis (anti-NMDA receptor antibodies more sensitive in CSF)
- Suspected Creutzfeldt-Jakob disease (14-3-3 protein, RT-QuIC assay)
- HIV-positive patients with new chorea
- Suspected infectious encephalitis
| CSF Finding | Conditions | Interpretation |
|---|---|---|
| Lymphocytic pleocytosis | Autoimmune encephalitis, viral encephalitis, neurosyphilis | Suggests inflammatory process; may be mild or absent in anti-NMDA receptor encephalitis |
| Elevated protein | Various inflammatory and infectious causes | Non-specific; supports inflammatory process |
| Oligoclonal bands | Multiple sclerosis, autoimmune encephalitis, chronic infections | Indicates intrathecal immunoglobulin synthesis |
| Anti-NMDA receptor antibodies | Anti-NMDA receptor encephalitis | More sensitive in CSF than serum; confirms diagnosis |
| 14-3-3 protein positive | Creutzfeldt-Jakob disease | Supportive but not specific; false positives occur |
| RT-QuIC positive | Creutzfeldt-Jakob disease | Highly specific (approximately 99%); confirms prion disease |
Key Neuroimaging Patterns
| MRI Finding | Conditions | Sequence |
|---|---|---|
| Caudate atrophy with “box car” ventricles | Huntington disease (advanced) | T1, T2 |
| Striatal T1 hyperintensity (unilateral) | Non-ketotic hyperglycemic chorea | T1 (characteristic) |
| Putaminal T2 hyperintensity + hypointense rim | Wilson disease (“face of the giant panda” in midbrain) | T2, FLAIR |
| Subthalamic or striatal infarct | Vascular hemichorea-hemiballismus | DWI (acute), T2/FLAIR |
| Medial temporal and frontal FLAIR hyperintensity | Autoimmune encephalitis | FLAIR, T2 |
| Cortical ribboning on DWI | Creutzfeldt-Jakob disease | DWI (most sensitive) |
| Caudate and putaminal atrophy + T2 changes | Neuroacanthocytosis syndromes | T1 (atrophy), T2 |
| Normal MRI | Early Huntington disease, tardive dyskinesia, drug-induced, metabolic | All sequences |
Approach to Genetic Testing
Sequential Genetic Testing Strategy:
- First-tier: HTT gene testing for Huntington disease (if clinical suspicion or family history)
- Second-tier (if HTT negative): Huntington disease-like gene panel (HDL1/JPH3, HDL2, SCA17, DRPLA)
- Third-tier: Broader movement disorder gene panel or whole exome sequencing
- Consider specific testing: VPS13A (chorea-acanthocytosis), XK (McLeod), NKX2-1 (benign hereditary chorea) based on phenotype
Genetic Counseling is Essential
Before ordering genetic testing for hereditary choreas (especially Huntington disease), ensure the patient has received genetic counseling. A positive result has profound implications not only for the patient but also for at-risk family members. Patients should understand:
- The implications of a positive result (no cure, progressive disease)
- The implications for family members (50% risk for first-degree relatives)
- Potential insurance and employment discrimination issues
- Reproductive options and testing for at-risk pregnancies
- The option not to know
Stepwise Investigation Algorithm
| Step | Investigations | Purpose |
|---|---|---|
| Step 1: Immediate (all patients) | Glucose, electrolytes, liver function, thyroid function, CBC with smear, HIV | Exclude metabolic and common reversible causes |
| Step 2: Imaging (all patients) | Brain MRI with contrast | Structural lesions, characteristic patterns |
| Step 3: Wilson workup (if under 50) | Ceruloplasmin, 24-hour urine copper, slit-lamp examination | Exclude treatable Wilson disease |
| Step 4: Autoimmune workup (if subacute or inflammatory features) | ANA, antiphospholipid antibodies, anti-NMDA receptor antibodies, ASO/anti-DNase B | Identify treatable autoimmune causes |
| Step 5: CSF analysis (if indicated) | Cell count, protein, glucose, oligoclonal bands, specific antibodies | Inflammatory, infectious, prion diseases |
| Step 6: Genetic testing (after counseling) | HTT gene; expanded panel if negative | Confirm hereditary causes |
7. Pattern Recognition and Clinical Decision-Making
Practical algorithms and decision pathways for chorea
Step 1: Is This Urgent?
| Clinical Scenario | Urgency Level | Immediate Action |
|---|---|---|
| Altered consciousness + chorea + fever | EMERGENT | Admit to ICU; empiric acyclovir; lumbar puncture; brain MRI; autoimmune panel; consider empiric immunotherapy |
| Acute hemichorea + elderly + diabetic | EMERGENT | Check glucose immediately; if hyperglycemic, initiate treatment; brain MRI; correct metabolic derangement |
| Sudden-onset hemichorea + vascular risk factors | EMERGENT | Acute stroke protocol; brain MRI with DWI; vascular imaging; neurology consultation |
| New chorea + psychiatric symptoms + seizures (young woman) | EMERGENT | Admit; anti-NMDA receptor antibodies (serum and CSF); pelvic imaging; empiric immunotherapy if high suspicion |
| Chorea + rapid cognitive decline + myoclonus | URGENT | Brain MRI with DWI; EEG; lumbar puncture for 14-3-3 and RT-QuIC; prion precautions |
| Young patient with chorea + liver abnormalities | URGENT | Wilson disease workup immediately (ceruloplasmin, 24-hour urine copper, slit-lamp); do not delay |
| Post-streptococcal chorea in child/adolescent | URGENT | ASO titer, anti-DNase B; echocardiogram for carditis; start penicillin prophylaxis |
| Chronic progressive chorea + family history + cognitive decline | ROUTINE | Genetic counseling; HTT gene testing; supportive care; multidisciplinary referral |
| Orofacial dyskinesia + chronic neuroleptic use | ROUTINE | Document exposure; assess severity; consider VMAT2 inhibitor; minimize offending agents |
| Mild chorea + stable + no red flags | ROUTINE | Complete baseline workup; Wilson disease exclusion if under 50; outpatient neurology referral |
Step 2: Classify by Duration and Onset
Acute (less than 2 weeks)
Priority: Exclude emergencies
Proceed to Algorithm A
- Check glucose
- Review medications
- Brain imaging
- Metabolic panel
Subacute (2 weeks to 6 months)
Priority: Autoimmune and inflammatory
Proceed to Algorithm B
- Autoimmune workup
- CSF analysis
- Malignancy screening
- Infectious workup
Chronic (greater than 6 months)
Priority: Hereditary and degenerative
Proceed to Algorithm C
- Wilson disease workup (if under 50)
- Family history review
- Genetic counseling
- Gene testing
Step 3: Follow the Appropriate Algorithm
Algorithm A: Acute Chorea
| Clinical Scenario | Most Likely Diagnosis | Action |
|---|---|---|
| Elderly + diabetes + hemichorea + glucose greater than 400 mg/dL | Non-ketotic hyperglycemic chorea | Correct hyperglycemia; brain MRI (expect T1 striatal hyperintensity); chorea resolves with glucose control |
| Recent medication change + temporal relationship | Drug-induced chorea | Discontinue offending agent; observe for resolution; symptomatic treatment if severe |
| Sudden onset + focal neurological signs + vascular risk factors | Stroke (subthalamic or striatal) | Brain MRI with DWI; vascular workup; secondary prevention; chorea often improves spontaneously |
| Stimulant use + sympathomimetic signs + agitation | Stimulant-induced chorea | Supportive care; benzodiazepines if needed; resolves with drug clearance |
| Acute onset + fever + altered consciousness | Encephalitis (infectious or autoimmune) | Emergent workup; empiric acyclovir; lumbar puncture; autoimmune panel; brain MRI |
Algorithm B: Subacute Chorea
| Clinical Scenario | Most Likely Diagnosis | Action |
|---|---|---|
| Young woman + psychiatric prodrome + seizures + autonomic instability | Anti-NMDA receptor encephalitis | Anti-NMDA receptor antibodies (CSF and serum); pelvic MRI/ultrasound for teratoma; initiate immunotherapy |
| Child/adolescent + recent sore throat + emotional lability | Sydenham chorea | ASO titer, anti-DNase B; echocardiogram; penicillin prophylaxis; symptomatic treatment; self-limited |
| Young woman + rash + arthralgia + positive ANA | Systemic lupus erythematosus chorea | Complete SLE workup; antiphospholipid antibodies; immunosuppressive therapy |
| Weight loss + smoking history + subacute chorea | Paraneoplastic syndrome | Paraneoplastic antibody panel; CT chest/abdomen/pelvis; PET-CT if high suspicion; treat underlying malignancy |
| HIV positive + new chorea | HIV-associated chorea or opportunistic infection | CD4 count; viral load; brain MRI; CSF analysis; optimize antiretroviral therapy |
Algorithm C: Chronic Chorea
| Clinical Scenario | Most Likely Diagnosis | Action |
|---|---|---|
| Family history + cognitive decline + psychiatric features | Huntington disease | Genetic counseling; HTT gene testing; multidisciplinary care; symptomatic treatment |
| Chronic neuroleptic exposure + orofacial predominant | Tardive dyskinesia | Document exposure; AIMS scale; minimize causative agents; VMAT2 inhibitors (tetrabenazine, deutetrabenazine, valbenazine) |
| Young patient + liver disease + Kayser-Fleischer rings | Wilson disease | Confirm diagnosis; initiate chelation therapy (penicillamine or trientine); zinc maintenance; monitor closely |
| Orofacial chorea + lip biting + elevated creatine kinase | Neuroacanthocytosis | Blood smear for acanthocytes; genetic testing (VPS13A or XK); supportive care; no disease-modifying therapy |
| Elderly + no family history + mild stable chorea + normal workup | Senile chorea | Diagnosis of exclusion; exclude all treatable causes; symptomatic treatment if bothersome |
| Huntington disease phenotype + negative HTT testing | Huntington disease-like syndrome | Expanded genetic panel (HDL1-4, SCA17, DRPLA); consider whole exome sequencing |
Decision Making by Distribution Pattern
| Distribution | Think First | Key Investigations |
|---|---|---|
| Hemichorea-hemiballismus (unilateral) | Contralateral structural lesion: stroke, hyperglycemia, tumor | Glucose; brain MRI with DWI; vascular imaging |
| Generalized chorea (symmetric) | Systemic cause: Huntington disease, drug-induced, metabolic, autoimmune | Metabolic panel; medication review; autoimmune workup; genetic testing |
| Orofacial predominant | Tardive dyskinesia; neuroacanthocytosis; edentulous dyskinesia | Medication history; blood smear; creatine kinase |
| Asymmetric but bilateral | Sydenham chorea; early Huntington disease; autoimmune | ASO titer; autoimmune panel; genetic testing |
“What Do I Do If…” Decision Reference
| Clinical Situation | Immediate Action | Next Step |
|---|---|---|
| Patient wants Huntington disease testing but has not had genetic counseling | Do not order test yet | Refer to genetic counselor; ensure patient understands implications before testing |
| Positive family history but patient does not want to know genetic status | Respect patient autonomy | Offer supportive care; monitor clinically; ensure patient knows testing remains available |
| Wilson disease suspected but ceruloplasmin normal | Continue workup—ceruloplasmin can be normal in 5-15% | 24-hour urine copper; slit-lamp examination; consider liver biopsy or genetic testing |
| Chorea is functionally disabling | Consider symptomatic treatment | VMAT2 inhibitors (tetrabenazine, deutetrabenazine); antipsychotics as second line; address underlying cause |
| Patient on neuroleptic develops new chorea | Differentiate tardive from acute drug-induced | If tardive: VMAT2 inhibitors, minimize neuroleptic; if acute: may need to adjust or change medication |
| HTT gene test is negative but phenotype is classic Huntington disease | Repeat testing to exclude technical error | If confirmed negative: test for Huntington disease-like syndromes (HDL1-4, SCA17, DRPLA) |
| Anti-NMDA receptor encephalitis suspected but antibodies negative | CSF antibodies are more sensitive than serum | If high clinical suspicion, consider empiric immunotherapy; repeat testing; search for teratoma |
| Hyperglycemic chorea not improving with glucose correction | Ensure adequate glucose control; may take days to weeks | Symptomatic treatment with dopamine blockers; chorea typically resolves eventually |
| Patient with chorea wants to drive | Assess severity and cognitive function | Formal driving evaluation if any concern; advise based on local regulations; document discussion |
| Chorea causing falls or injury | Safety assessment; fall precautions | Physical therapy; home safety evaluation; consider pharmacological treatment; assistive devices |
Troubleshooting Refractory Chorea
When Chorea Does Not Improve — Ask These Questions
- Is the diagnosis correct? Re-review the case; consider alternative diagnoses; repeat key investigations
- Is there an underlying cause that was not addressed? Drug exposure still ongoing; metabolic derangement not corrected; occult malignancy
- Are there multiple overlapping causes? For example, Huntington disease patient also taking metoclopramide
- Is the treatment adequate? Appropriate medication; adequate dose; sufficient duration
- Is there medication non-adherence? Check with patient; consider simplified regimen
- Has the disease progressed? Natural history of condition; need for treatment escalation
- Is this a non-organic component? Functional movement disorder can coexist with organic disease
When to Refer to a Movement Disorder Specialist
Urgent Referral
- Diagnostic uncertainty after initial workup
- Suspected Huntington disease (for genetic counseling coordination)
- Young patient with unexplained chorea
- Rapidly progressive or disabling symptoms
- Complex phenotype with multiple movement disorders
Routine Referral
- Confirmed hereditary chorea for long-term management
- Tardive dyskinesia not responding to initial treatment
- Need for specialized therapies (deep brain stimulation consideration)
- Clinical trial eligibility assessment
- Second opinion requested by patient
8. Clinical Pearls and Pitfalls
Practical wisdom — learn from successes and avoid common mistakes
Must-Know Clinical Pearls
Always check glucose in acute hemichorea: Non-ketotic hyperglycemia is one of the most common causes of acute hemichorea-hemiballismus in elderly patients and is completely reversible with glucose correction. A bedside glucose check takes seconds and can prevent extensive unnecessary workup.
Wilson disease is treatable—never miss it: In any patient under 50 years with chorea (or any movement disorder), Wilson disease must be excluded. Early treatment can halt progression and even reverse symptoms. The workup is straightforward: ceruloplasmin, 24-hour urine copper, and slit-lamp examination.
A negative family history does not exclude Huntington disease: Up to 8% of Huntington disease cases appear sporadic due to non-paternity, early parental death, intermediate alleles with expansion, or family secrecy. If the phenotype is suggestive, pursue genetic testing after appropriate counseling.
Metoclopramide and prochlorperazine cause tardive dyskinesia: These commonly prescribed antiemetics are dopamine receptor blockers with the same tardive risk as antipsychotics. Always ask specifically about these medications when evaluating chorea—patients often do not consider them “psychiatric medications.”
Observe the patient when they think you are not looking: Chorea is often more prominent when the patient is distracted or unaware of observation. Watch during history-taking, when the patient is looking away, or during casual conversation for the most accurate assessment.
Motor impersistence is the hallmark of chorea: Test for “milkmaid’s grip” (fluctuating grip strength) and “serpentine tongue” (inability to keep tongue protruded). These signs are highly characteristic and help confirm the choreiform nature of movements.
Anti-NMDA receptor encephalitis is more common than previously thought: In young women with new psychiatric symptoms, seizures, and movement disorders, this treatable condition should be high on the differential. CSF antibody testing is more sensitive than serum. Early immunotherapy dramatically improves outcomes.
The striatal T1 hyperintensity of hyperglycemic chorea is nearly pathognomonic: On brain MRI, unilateral T1-weighted hyperintensity in the striatum contralateral to hemichorea, in the context of severe hyperglycemia, essentially confirms the diagnosis. This finding can persist even after clinical resolution.
Critical Pitfalls to Avoid
Ordering Huntington disease genetic testing without genetic counseling: A positive result has profound implications for the patient and their family. Testing should only be performed after appropriate genetic counseling, informed consent, and assessment of psychological readiness. This is not a test to order casually.
Forgetting to check glucose in acute chorea: Hyperglycemic chorea is common, completely reversible, and easily diagnosed—yet frequently missed. A simple point-of-care glucose test should be performed immediately in any patient presenting with acute chorea, especially if elderly or diabetic.
Assuming Wilson disease is excluded by normal ceruloplasmin: Ceruloplasmin is normal in 5-15% of patients with Wilson disease. If clinical suspicion exists, proceed with 24-hour urine copper, slit-lamp examination for Kayser-Fleischer rings, and consider genetic testing or liver biopsy.
Missing medication-induced chorea: Always take a thorough medication history including over-the-counter drugs, herbal supplements, and antiemetics. Drug-induced chorea is common and reversible. Patients may not volunteer information about medications they consider unrelated.
Treating tardive dyskinesia by stopping the neuroleptic abruptly: Abrupt discontinuation can initially worsen tardive dyskinesia (withdrawal dyskinesia) and may precipitate psychiatric decompensation. Gradual tapering with close monitoring is preferred. VMAT2 inhibitors are first-line treatment.
Attributing all movements in a known Huntington disease patient to disease progression: Patients with Huntington disease can develop other causes of chorea (drug-induced, metabolic) or other movement disorders. New or changing symptoms warrant fresh evaluation rather than automatic attribution to the known diagnosis.
Dismissing chorea in the elderly as “just age-related”: While senile chorea exists, it is a diagnosis of exclusion. Elderly patients can have treatable causes including hyperglycemia, drug-induced chorea, stroke, and even late-onset Huntington disease. Complete workup is still required.
Failing to look for ovarian teratoma in anti-NMDA receptor encephalitis: Up to 50% of women with anti-NMDA receptor encephalitis have an underlying ovarian teratoma. Tumor removal is often essential for recovery. Pelvic imaging (MRI or ultrasound) should be performed in all cases, and repeat imaging is warranted if initial studies are negative.
Key Takeaways
- Chorea is a symptom, not a diagnosis: The underlying cause must always be sought. The differential is broad, ranging from treatable metabolic and drug-induced causes to progressive neurodegenerative conditions.
- Prioritize treatable and reversible causes: Before pursuing genetic testing for Huntington disease, exclude drug-induced chorea, Wilson disease (in patients under 50), hyperglycemia, autoimmune conditions, and structural lesions.
- Duration guides the differential: Acute chorea suggests stroke, metabolic, or drug-related causes. Subacute chorea raises concern for autoimmune or paraneoplastic etiologies. Chronic progressive chorea points toward hereditary conditions.
- Distribution provides diagnostic clues: Hemichorea suggests a contralateral structural lesion. Orofacial predominance suggests tardive dyskinesia or neuroacanthocytosis. Generalized chorea has a broader differential.
- Wilson disease must be excluded in all patients under 50: This is one of the few treatable causes of progressive neurological decline. The standard workup includes ceruloplasmin, 24-hour urine copper, and slit-lamp examination.
- Genetic counseling must precede Huntington disease testing: The implications of a positive result extend beyond the individual patient to affect the entire family. Testing should never be performed without proper preparation and support.
- Medication history is critical: Both acute and tardive drug-induced chorea are common. Ask specifically about neuroleptics, antiemetics (metoclopramide, prochlorperazine), dopaminergic agents, and stimulants.
- Anti-NMDA receptor encephalitis is treatable: This increasingly recognized condition presents with psychiatric symptoms, seizures, and movement disorders. Early immunotherapy and tumor removal (if present) dramatically improve outcomes.
- Hyperglycemic chorea is a “cannot miss” diagnosis: It is common, easily diagnosed, and completely reversible. Check glucose immediately in any patient with acute-onset chorea.
- Symptomatic treatment is available: While addressing the underlying cause is paramount, VMAT2 inhibitors (tetrabenazine, deutetrabenazine, valbenazine) and other agents can significantly improve quality of life for patients with disabling chorea.
Quick Reference Algorithm
Systematic Approach to Chorea:
- Assess urgency: Is there altered consciousness, fever, acute stroke presentation, or metabolic emergency? If yes, initiate emergent workup and treatment.
- Check glucose immediately: Especially in elderly patients with acute hemichorea—hyperglycemic chorea is common and reversible.
- Review all medications: Identify any drugs that can cause chorea (neuroleptics, antiemetics, dopaminergics, stimulants, anticonvulsants).
- Classify by duration: Acute (less than 2 weeks), subacute (2 weeks to 6 months), or chronic (greater than 6 months)—this guides the differential and workup.
- Perform baseline investigations: Complete blood count with smear, metabolic panel, thyroid function, ESR/CRP, ANA, HIV, and brain MRI for all patients.
- Exclude Wilson disease if under 50 years: Ceruloplasmin, 24-hour urine copper, slit-lamp examination—do not skip this step.
- Consider autoimmune causes in subacute presentations: Anti-NMDA receptor antibodies, antiphospholipid antibodies, ASO/anti-DNase B; lumbar puncture if indicated.
- Pursue genetic testing with appropriate counseling: If hereditary cause suspected after excluding treatable conditions, arrange genetic counseling before HTT gene testing.
- Initiate symptomatic treatment if needed: VMAT2 inhibitors are first-line for disabling chorea; address underlying cause simultaneously.
- Arrange appropriate follow-up: Movement disorder specialist referral for complex cases, genetic counseling for hereditary conditions, multidisciplinary care for progressive diseases.