Hemichorea

Overview

Hemichorea (also known as hemichorea) is a movement disorder characterized by involuntary, irregular, purposeless movements that resemble dance-like motions affecting one side of the body. The term derives from the Greek words “hemi-” (half) and “chorea” (dance), reflecting the characteristic dancing or jerky quality of the movements. ^{1Shannon KM, Comella CL. Treatment of hyperkinetic movement disorders. Lancet Neurology. 20092009 · PMID 19398973Open reference}

Hemichorea exists on a spectrum with hemiballismus, with both conditions resulting from dysfunction in the basal ganglia motor circuits, particularly involving the striatum and subthalamic nucleus. ^{2Walker RH. Differential diagnosis of chorea. Practical Neurology. 20112011 · PMID 21921002Open reference}

Clinical Presentation

Core Symptoms

• Movement characteristics:

  • Random, irregular, jerky movements

  • Non-repetitive and non-rhythmic

  • Flowing quality (like piano playing)

  • Often continuous during waking hours

  • May decrease during sleep

• Distribution:

  • Primarily affects the face, arm, and leg on one side

  • Can involve proximal and distal muscles

  • May vary in severity throughout the day

Associated Features

• Motor impersistence: Inability to maintain sustained postures

• Motor weakness: Often coexists with weakness on the affected side

• Cognitive changes: May accompany cognitive impairment in neurodegenerative cases

Etiology

Vascular Causes (Most Common)

Stroke

• Lacunar strokes affecting:

  • Striatum (putamen, caudate)

  • Subthalamic nucleus

  • Thalamus

  • Globus pallidus

• Small vessel disease

• Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Metabolic Causes

• Non-ketotic hyperglycemia - Increasingly recognized cause in elderly patients

• Hypoglycemia

• Thyroid dysfunction (thyroid-related movement disorders)

• Electrolyte disturbances:

  • Hyponatremia

  • Hypernatremia

  • Hypocalcemia

Neurodegenerative Diseases

• Huntington’s disease and Juvenile Huntington’s disease

• Wilson disease - Copper accumulation

• Neuroacanthocytosis syndromes

• C9orf72 expansions (ALS/FTD spectrum)

Autoimmune/Inflammatory

• Systemic lupus erythematosus (SLE)

• Autoimmune encephalitis

• Antiphospholipid syndrome

• CNS vasculitis

Infectious

• HIV-associated encephalopathy

• Syphilis (general paresis)

• Viral encephalitis (post-infectious)

Drug-Induced

• Levodopa-induced dyskinesias

• Antipsychotic medications (tardive chorea)

• Phenytoin

• Oral contraceptives

Pathophysiology

Basal Ganglia Dysfunction

Hemichorea results from disruption of the normal inhibitory-excitatory balance in the basal ganglia motor circuit: ^{3Postuma RB, Lang AE. Hemiballismus: Consenting to treat. Neurology. 20032003 · PMID 14504320Open reference}

flowchart LR
    subgraph N["ormal"]
    C["Cortex"] --> P["Putamen"]
    P --> GG["Pi"]
    G --> T["Thalamus"]
    T --> C
    STNSTN -.->|"excitatory"| G
    end

    subgraph D["ysfunction"]
    C2["Cortex"] --> P2["Putamen"]
    P2 -.-|"lesion"| X
    X -->|"reduced inhibition"| T2["Thalamus"]
    T2 --> C2
    end

Neurochemical Changes

1. Dopamine dysregulation: Either excess or deficiency

2. GABAergic dysfunction: Reduced inhibitory control

3. Cholinergic deficiency: Particularly in the striatum

Regional Involvement

• Striatal lesions: Most common cause (especially putamen)

• Subthalamic nucleus: More associated with ballismus

• Thalamic involvement: Can produce chorea

Diagnosis

Clinical Evaluation

1. History:

   • Acute vs. gradual onset

   • Vascular risk factors

   • Medication history

   • Family history of movement disorders

2. Neurological examination:

   • Distribution of movements

   • Associated weakness

   • Cognitive assessment

   • Search for signs of systemic disease

Diagnostic Workup

Neuroimaging

• MRI brain: Gold standard for structural lesions

  • T2/FLAIR hyperintensities (stroke,代谢)

  • Gradient echo (cavernous malformations)

• CT brain: Acute hemorrhage

• MR angiography: Vascular malformations

Laboratory Studies

• Metabolic panel: Glucose, electrolytes, liver function

• Thyroid function tests: TSH, free T4

• Copper studies: Ceruloplasmin, 24-hour urine (Wilson disease)

• Autoimmune screening: ANA, antiphospholipid antibodies

• Genetic testing:

  • Huntington disease gene testing

  • Wilson disease ATP7B testing

Cerebrospinal Fluid

• Exclude infectious causes

• Oligoclonal bands

• Autoantibody panels

Treatment

Acute/Short-Term Management

Pharmacotherapy

1. Dopamine-depleting agents:

   • Tetrabenazine: 12.5-200 mg/day

   • Deutetrabenazine: 6-48 mg/day (FDA-approved for Huntington chorea)

2. Dopamine receptor blockers:

   • Haloperidol: 1-10 mg/day

   • Olanzapine: 5-20 mg/day

   • Risperidone: 1-6 mg/day

3. Benzodiazepines:

   • Clonazepam: 0.5-3 mg/day

   • Diazepam: 5-20 mg/day

4. Anticonvulsants:

   • Valproic acid: 500-2000 mg/day

   • Levetiracetam: 1000-3000 mg/day

   • Carbamazepine: 400-1200 mg/day

Long-Term Management

Treatment of Underlying Cause

• Vascular: Secondary stroke prevention

• Metabolic: Glucose control, thyroid replacement

• Wilson disease: Chelation therapy

• Autoimmune: Immunomodulation

• Drug-induced: Discontinue offending agent

Surgical Options

• Deep brain stimulation (DBS):

  • Target: Globus pallidus interna (GPi)

  • Effective for chorea in Huntington disease

Supportive Care

• Physical therapy for injury prevention

• Occupational therapy

• Speech therapy if bulbar involvement

• Psychological support

Prognosis

Variable Outcomes

• Post-stroke: Often improves over weeks to months

• Metabolic causes: Usually resolves with treatment of underlying cause

• Neurodegenerative: Often progressive, requires chronic management

• Drug-induced: May resolve after discontinuation

Factors Influencing Prognosis

• Etiology: Metabolic and vascular causes have better outcomes

• Age: Younger patients often have better recovery

• Treatment response: Early intervention improves outcomes

• Underlying disease progression: Neurodegenerative causes are progressive

Relationship to Hemiballismus

Hemichorea and hemiballismus represent a spectrum of hyperkinetic movement disorders: ^{4Non-ketotic hyperglycemia presenting with hemiballismus and hemichorea. Journal of Neurology. 20122012 · PMID 22446854Open reference}

| Feature | Hemichorea | Hemiballismus | ^{5Cardoso F. Chorea: A journey through history. Tremor and Other Hyperkinetic Movements. 20152015 · PMID 26175779Open reference} |---------|------------|---------------| ^{6Huntington Study Group. Tetrabenazine therapy for chorea. Neurology. 20062006 · PMID 16476936Open reference} | Movement | Small, dancelike | Large, flinging | ^{7Surgical treatment of movement disorders. Journal of Neurology, Neurosurgery & Psychiatry. 20132013 · PMID 23400136Open reference} | Severity | Moderate | Severe | | STN involvement | Less prominent | Primary | | Prognosis | Generally better | More variable |

Both conditions result from basal ganglia dysfunction and may respond to similar treatments.

See Also

• Hemiballismus

• Subthalamic Nucleus

• Lacunar Strokes

• Thyroid-Related Movement Disorders

• Huntington’s Disease

• Juvenile Huntington’s Disease

• Wilson Disease

• Neuroacanthocytosis Syndromes

• C9orf72 Expansions

• Autoimmune Encephalitis

External Links

• PubMed

• KEGG Pathways

Recent Research (2024-2026)

Recent research on Hemichorea includes:

• 2024: Title - Description