What is Chorea
Chorea is a hyperkinetic movement disorder characterized by irregular, rapid, non-stereotyped involuntary movements that flow randomly from one body part to another, creating a "dance-like" appearance during movement. 1
Clinical Phenomenology
Movement Characteristics:
- The movements are involuntary, jerky, and can involve any part of the body in random sequence 1
- When mild, chorea may be difficult to differentiate from simple restlessness 2
- The movements possess a flowing quality and are brief, random muscle contractions that shift unpredictably between body regions 3, 4
- When chorea is proximal and of large amplitude, it is termed ballism 2, 5
Behavioral Features:
- Movements are present at rest and increase with distracting maneuvers 3
- Can be partially suppressed voluntarily and often disappear during sleep 3, 5
- Worsened by stress and anxiety 2, 5
- Patients frequently attempt to disguise choreic movements by incorporating them into purposeful activities 2, 5
Associated Features:
- Motor impersistence is common, demonstrated by varying grip strength ("milkmaid's grasp") or inability to sustain eye closure or tongue protrusion 2
- May be associated with weakness and emotional lability 1
- Can interfere significantly with activities of daily living, making simple tasks like fastening buttons difficult 2
Pathophysiology
Neuroanatomical Basis:
- Chorea originates from dysfunctional neuronal networks interconnecting the basal ganglia and frontal cortical motor areas 4
- Results from disruption of the normal balance within basal ganglia circuits 4
Etiological Classification
Hereditary Causes:
- Huntington's disease is the most frequent cause of hereditary chorea 3
- Benign Hereditary Chorea (BHC) is caused by mutations or deletions in the NKX2-1/TITF1 gene on chromosome 14q13.3 6
Acquired Causes:
- Medication-induced chorea is the most frequent cause of acquired chorea 3
- Cerebrovascular disease and space-occupying lesions 3
- Immune-based choreas (including systemic lupus erythematosus and antiphospholipid syndrome) 1, 3
- Infectious causes 3
- Toxic and metabolic encephalopathies 3
- Sydenham's chorea is the most common form of childhood chorea 5
Pattern Recognition:
- When dealing with hemichorea, it is essential to rule out structural insult of the basal ganglia or their connections 3
- Chorea may occur as a single episode that subsides within days to a few months (55-65% of cases) and can be associated with antiphospholipid antibodies 1
Differential Diagnosis
Key Distinctions:
- Tics are very brief movements, typically of shorter duration than choreic movements 6, 7
- Athetosis consists of slower and more twisted movements compared to chorea 7
- Akathisia is characterized by severe restlessness with both subjective and objective components, often manifested as pacing or physical agitation 1
- Hyperkinesia, conversion reactions, and psychogenic movement disorders must be distinguished from true chorea 6, 7