What are the causes of hemichorea?

Causes of Hemichorea

Hemichorea is most commonly caused by cerebrovascular disease, metabolic disorders (particularly hyperglycemia), autoimmune conditions, and certain genetic disorders. 1, 2

Cerebrovascular Causes

• Ischemic or hemorrhagic stroke affecting the contralateral basal ganglia, particularly the striatum 3, 4
• Post-varicella vasculopathy can present with isolated hemichorea in pediatric patients 4
• Vascular malformations affecting blood flow to the basal ganglia 2

Metabolic Causes

• Non-ketotic hyperglycemia is a well-recognized cause, particularly in older females with new-onset or poorly controlled type 2 diabetes 5
  • Presents with characteristic T1 hyperintensity in the striatum on MRI
  • May resolve with treatment of hyperglycemia or persist for years
• Other metabolic disturbances:
  • Hypoparathyroidism and related calcium abnormalities 5
  • Hypoglycemia (less common than hyperglycemia) 5
  • Hypernatremia 5

Autoimmune Causes

• Systemic lupus erythematosus with central nervous system involvement 6, 2
• Antiphospholipid syndrome 6, 2
• Post-infectious autoimmune disorders (PANDAS - Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections) 2

Genetic and Neurodegenerative Causes

• Huntington's disease (most common cause of adult-onset generalized chorea, but can present with asymmetric or unilateral symptoms) 6, 2
• Huntington's disease-like syndromes (HDL1-3) 2
• Neuroacanthocytosis 2
• Spinocerebellar ataxias (particularly types 1,3, and 17) 2
• Dentatorubral-pallidoluysian atrophy (DRPLA) 1, 2
• Benign hereditary chorea (mutations in NKX2-1/TITF1 gene) 7, 2
• Inherited prion disease 2
• Wilson's disease 2
• Brain iron accumulation disorders 2

Other Causes

• Drug-induced (particularly neuroleptics, anticonvulsants, oral contraceptives, cocaine) 6, 2
• Thyrotoxicosis 2
• HIV/AIDS-related complications 2
• Chorea gravidarum (pregnancy-related) 2
• Polycythemia vera 2
• Paraneoplastic syndromes 1

Diagnostic Approach

• Brain MRI without contrast is the optimal initial imaging modality to identify structural causes and assess for neurodegenerative patterns 6
• Metabolic workup including glucose, calcium, thyroid function, and parathyroid hormone levels 5
• Autoimmune panel including antinuclear antibodies, antiphospholipid antibodies when appropriate 6
• Genetic testing when hereditary causes are suspected 6, 7

Clinical Pearls

• Recurrent hemichorea may be caused by different etiologies in the same patient 3
• Isolated hemichorea can be the sole manifestation of post-infectious vasculopathy in children 4
• Hyperglycemic hemichorea typically affects older females and often heralds a new diagnosis of diabetes 5
• Brain MRI in hyperglycemic hemichorea characteristically shows T1 hyperintensity in the contralateral striatum 5

When evaluating a patient with hemichorea, a systematic approach focusing on vascular, metabolic, autoimmune, and genetic causes is essential for accurate diagnosis and appropriate management.