What are the causes and treatment options for migratory hemichorea?

Migratory Hemichorea: Causes and Treatment

Overview

Migratory hemichorea is an extremely rare presentation where involuntary choreiform movements shift from one side of the body to the other, most commonly caused by sequential vascular events (strokes), non-ketotic hyperglycemia in diabetics, or autoimmune/infectious processes affecting the basal ganglia bilaterally or sequentially.

Causes

Vascular Etiologies (Most Common)

• Sequential strokes affecting contralateral basal ganglia structures, particularly the subthalamic nucleus, caudate, or putamen, represent the most frequent cause of migratory hemichorea 1, 2
• Severe middle cerebral artery stenosis can cause delayed perfusion leading to hemichorea, which may migrate if bilateral vascular compromise develops 2
• Intracranial hemorrhage in the subthalamic nucleus can trigger hemichorea-hemiballismus 3

Metabolic Causes

• Non-ketotic hyperglycemia in poorly-controlled diabetes mellitus, particularly in elderly women, causes hemichorea through basal ganglia dysfunction 4
• This presents with contralateral basal ganglia hyperintensity on T1-weighted MRI or high density on CT scans 4
• The mechanism involves metabolic disruption of striatal neurons leading to disinhibition of thalamocortical pathways 4

Autoimmune/Infectious Causes

• Post-infectious autoimmune CNS disorders (PANDAS) can cause migratory chorea 5
• Systemic lupus erythematosus and antiphospholipid syndrome may present with chorea that shifts sides 5
• Neurocysticercosis can rarely present with focal neurological signs including hemichorea if lesions affect basal ganglia bilaterally or sequentially 6

Other Systemic Causes

• Thyrotoxicosis, polycythemia rubra vera, and AIDS-related complications 5
• Drug-induced chorea (dopamine agonists, stimulants, anticonvulsants) 5

Diagnostic Approach

Neuroimaging

• Brain MRI with DWI sequences to identify acute ischemic lesions in basal ganglia, particularly subthalamic nucleus 2, 3
• T1-weighted imaging shows hyperintensity in basal ganglia with non-ketotic hyperglycemia 4
• CT perfusion (CTP) with time-to-peak (TTP) measurements identifies delayed perfusion in vascular causes 2
• MRA to evaluate for cerebrovascular stenosis or occlusion 2

Laboratory Evaluation

• Blood glucose and HbA1c to identify non-ketotic hyperglycemia (critical in diabetics) 4
• Complete metabolic panel including electrolytes, renal function, liver function 5
• Thyroid function tests (TSH, free T4) 5
• Antiphospholipid antibodies, ANA, anti-dsDNA for autoimmune causes 5
• Blood smear for acanthocytes (neuroacanthocytosis) 3
• HIV testing in appropriate clinical context 5

Specialized Testing

• Genetic testing only after appropriate counseling if hereditary causes suspected (Huntington's disease, neuroacanthocytosis, Wilson's disease) 5
• Ceruloplasmin and 24-hour urinary copper for Wilson's disease in patients under 40 years 5

Treatment

Acute Management Based on Etiology

For Vascular Causes

• Antithrombotic therapy (antiplatelet or anticoagulation depending on stroke mechanism) as primary treatment 2
• Address underlying cerebrovascular disease with risk factor modification 2
• Symptomatic control with dopamine receptor antagonists if movements are disabling 3

For Non-Ketotic Hyperglycemia

• Strict blood glucose control is the foundational treatment - this is essential and often sufficient 4
• Target normoglycemia with insulin therapy, adjusting oral hypoglycemics as needed 4
• Add dopamine receptor antagonists (haloperidol starting at 0.5-1.5 mg/day, maximum 4.5 mg/day) for symptomatic control while glucose normalizes 4, 3
• Benzodiazepines (clonazepam 0.5-2 mg/day) as adjunctive sedative therapy 4

Symptomatic Pharmacotherapy

Dopamine receptor antagonists are first-line for symptomatic control regardless of etiology:

• Haloperidol 0.5-4.5 mg/day (titrate slowly to minimize extrapyramidal side effects) 3
• Alternative agents include risperidone, olanzapine, or quetiapine if haloperidol not tolerated 5

Second-line agents:

• Tetrabenazine (depletes presynaptic dopamine) for refractory cases 5
• Benzodiazepines for additional sedation and movement suppression 4

Novel Neuromodulation Therapy

Low-frequency repetitive transcranial magnetic stimulation (rTMS) shows dramatic efficacy for refractory hemichorea-hemiballismus:

• Protocol: 1 Hz, 1200 pulses, 90% resting motor threshold, applied to contralateral precentral knob (primary motor cortex) 3
• Frequency: 3 days/week for 2 weeks 3
• This suppresses excessive cortical excitation in thalamocortical circuits 3
• Consider for cases unresponsive to pharmacotherapy, particularly hemorrhagic causes 3

Critical Pitfalls to Avoid

• Do not dismiss acute-onset hemichorea as a benign movement disorder - it may be the initial presentation of stroke requiring urgent intervention 2
• Always check blood glucose in diabetic patients presenting with hemichorea, as hyperglycemia is a reversible cause 4
• Evaluate each recurrent episode independently - migratory hemichorea can have different etiologies in the same patient (e.g., initial stroke followed by hyperglycemic episode) 1
• Rule out infectious, toxic, and metabolic encephalopathy through comprehensive laboratory evaluation before attributing to structural lesions 2
• Avoid excessive doses of dopamine antagonists - start low and titrate slowly to prevent iatrogenic parkinsonism 3

Monitoring and Follow-Up

• Serial neuroimaging to assess lesion evolution and identify new contralateral lesions explaining migratory pattern 1
• Continuous glucose monitoring in diabetic patients until stable normoglycemia achieved 4
• Regular assessment of movement disorder severity to guide medication adjustments 3
• Long-term vascular risk factor management for stroke-related cases 2