What conditions should be included in the differential diagnosis of an adult‑onset progressive chorea that worsens over time and persists during sleep?

Differential Diagnosis of Adult-Onset Progressive Chorea Persisting During Sleep

The presence of chorea that persists during sleep is highly atypical and should immediately raise suspicion for Creutzfeldt-Jakob disease (CJD) or other prion diseases, as typical choreiform disorders like Huntington disease characteristically cease during deep sleep stages. 1

Key Distinguishing Feature: Sleep Persistence

The persistence of movements during sleep is the critical diagnostic clue here that dramatically narrows your differential:

• Normal chorea behavior: Choreiform movements typically increase with stress and physical activity but essentially cease during deep sleep stages 1
• Red flag: Movements continuing during sleep suggest a different pathophysiology, most notably prion disease 2

Primary Differential Considerations

1. Prion Disease (Creutzfeldt-Jakob Disease)

This should be your top consideration given the sleep persistence:

• CJD presents with rapidly progressive dementia and movement disorders
• MRI shows T2 hyperintensity and diffusion restriction in gray matter structures, including the basal ganglia (60%, predominantly anterior caudate and putamen) 2
• The hallmark is prominence of gray matter involvement with relative sparing of underlying white matter 2
• Diagnostic approach: MRI brain with DWI and T2-FLAIR sequences is optimal; consider CSF testing for 14-3-3 protein and RT-QuIC

2. Huntington Disease (HD)

While HD is the most common cause of adult-onset chorea 2, the sleep persistence makes this less likely:

• Typical onset age 35-45 years with autosomal dominant inheritance 2
• Progressive behavioral symptoms, choreoathetosis, and cognitive dysfunction
• Critical point: In advanced HD, choreiform movements should decrease during sleep, not persist 1
• Diagnostic approach: Genetic testing for CAG repeats (>38 confirms diagnosis) with genetic counseling 2
• MRI shows progressive caudate atrophy with frontal horn enlargement of lateral ventricles 2

3. Huntington Disease-Like Syndromes (HDL)

If HD genetic testing is negative, consider phenocopies 3:

• HDL1 (prion protein gene)
• HDL2 (junctophilin-3 gene, more common in African ancestry)
• HDL3 and other genetic variants
• These typically follow the same sleep pattern as HD (cessation during deep sleep)

4. Neuroacanthocytosis Syndromes

• Can present with progressive chorea in adulthood
• Associated with peripheral blood smear showing acanthocytes
• May have elevated creatine kinase
• Sleep disorders are documented but movements typically reduce during sleep 4

5. Acquired Causes to Exclude

Even with progressive symptoms, rapidly exclude treatable causes:

• Autoimmune/inflammatory: Anti-IgLON5 antibody syndrome (specifically associated with sleep disorders and chorea) 4
• Cerebrovascular disease: Basal ganglia strokes or hemorrhages
• Metabolic: Thyrotoxicosis, hyperglycemia (chorea-ballism syndrome)
• Drug-induced: Tardive dyskinesia (though typically improves with sleep)
• Systemic lupus erythematosus/antiphospholipid syndrome
• Wilson disease: Must exclude in any adult <40 with movement disorder

Diagnostic Algorithm

Step 1: Urgent MRI brain without contrast

• Look for: Caudate atrophy (HD), diffusion restriction in gray matter (CJD), basal ganglia signal changes (metabolic/vascular)
• Add DWI and T2-FLAIR sequences if CJD suspected 2

Step 2: Targeted laboratory workup

• Complete blood count with peripheral smear (acanthocytes)
• Comprehensive metabolic panel, thyroid function
• Ceruloplasmin and 24-hour urine copper (Wilson disease if age <40)
• ESR, ANA, antiphospholipid antibodies
• Creatine kinase

Step 3: Genetic counseling and testing

• HD genetic testing first (most common) 2
• If negative and phenotype fits: HDL panel, neuroacanthocytosis genes
• Consider prion protein gene testing if imaging suggests prion disease

Step 4: Specialized testing based on findings

• CSF analysis with 14-3-3 protein and RT-QuIC if CJD suspected
• Anti-IgLON5 antibodies if sleep-predominant symptoms 4
• Polysomnography to characterize sleep architecture and confirm movement persistence

Critical Pitfalls

• Don't assume HD without genetic confirmation: Multiple phenocopies exist 3
• Don't miss Wilson disease: Treatable but fatal if missed; check in all patients <40
• Don't delay prion disease workup: The sleep persistence is your clue; CJD is rapidly progressive with poor prognosis
• Don't forget medication history: Tardive dyskinesia can mimic neurodegenerative chorea but improves with sleep 5

The atypical feature of sleep persistence fundamentally changes your diagnostic approach from the standard HD-focused workup to one that prioritizes prion disease and other rare causes with altered sleep physiology.