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.
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.
- 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
- Lacunar strokes affecting:
- Striatum (putamen, caudate)
- Subthalamic nucleus
- Thalamus
- Globus pallidus
- Small vessel disease
- Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)
- Non-ketotic hyperglycemia - Increasingly recognized cause in elderly patients
- Hypoglycemia
- Thyroid dysfunction (thyroid-related movement disorders)
- Electrolyte disturbances:
- Hyponatremia
- Hypernatremia
- Hypocalcemia
- Huntington's disease and Juvenile Huntington's disease
- Wilson disease - Copper accumulation
- Neuroacanthocytosis syndromes
- C9orf72 expansions (ALS/FTD spectrum)
- Systemic lupus erythematosus (SLE)
- Autoimmune encephalitis
- Antiphospholipid syndrome
- CNS vasculitis
- HIV-associated encephalopathy
- Syphilis (general paresis)
- Viral encephalitis (post-infectious)
- Levodopa-induced dyskinesias
- Antipsychotic medications (tardive chorea)
- Phenytoin
- Oral contraceptives
Hemichorea results from disruption of the normal inhibitory-excitatory balance in the basal ganglia motor circuit:
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
- Dopamine dysregulation: Either excess or deficiency
- GABAergic dysfunction: Reduced inhibitory control
- Cholinergic deficiency: Particularly in the striatum
- Striatal lesions: Most common cause (especially putamen)
- Subthalamic nucleus: More associated with ballismus
- Thalamic involvement: Can produce chorea
-
History:
- Acute vs. gradual onset
- Vascular risk factors
- Medication history
- Family history of movement disorders
-
Neurological examination:
- Distribution of movements
- Associated weakness
- Cognitive assessment
- Search for signs of systemic disease
- 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
- 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
- Exclude infectious causes
- Oligoclonal bands
- Autoantibody panels
-
Dopamine-depleting agents:
- Tetrabenazine: 12.5-200 mg/day
- Deutetrabenazine: 6-48 mg/day (FDA-approved for Huntington chorea)
-
Dopamine receptor blockers:
- Haloperidol: 1-10 mg/day
- Olanzapine: 5-20 mg/day
- Risperidone: 1-6 mg/day
-
Benzodiazepines:
- Clonazepam: 0.5-3 mg/day
- Diazepam: 5-20 mg/day
-
Anticonvulsants:
- Valproic acid: 500-2000 mg/day
- Levetiracetam: 1000-3000 mg/day
- Carbamazepine: 400-1200 mg/day
- Vascular: Secondary stroke prevention
- Metabolic: Glucose control, thyroid replacement
- Wilson disease: Chelation therapy
- Autoimmune: Immunomodulation
- Drug-induced: Discontinue offending agent
- Physical therapy for injury prevention
- Occupational therapy
- Speech therapy if bulbar involvement
- Psychological support
- 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
- 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
Hemichorea and hemiballismus represent a spectrum of hyperkinetic movement disorders:
| Feature | Hemichorea | Hemiballismus |
|---------|------------|---------------|
| Movement | Small, dancelike | Large, flinging |
| 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.
Recent research on Hemichorea includes:
- 2024: Title - Description