What causes and treats abnormal jerky movements (chorea)?

Abnormal Jerky Movements on Movement of Body

Immediate Diagnostic Distinction

The first critical step is determining whether these jerky movements are triggered by sudden motion (paroxysmal kinesigenic dyskinesia) versus occurring spontaneously (chorea or myoclonus), as this fundamentally changes both diagnosis and treatment. 1

Movement-Triggered Jerks: Paroxysmal Kinesigenic Dyskinesia (PKD)

If movements are triggered by sudden motion (standing up quickly, being startled, initiating movement):

• Start carbamazepine or oxcarbazepine immediately - these low-dose voltage-gated sodium channel blockers are highly effective first-line treatment for PKD 1, 2
• PKD attacks are brief (seconds to minutes), stereotyped, and consciousness is preserved throughout 1
• Look for clear kinesigenic triggers: sudden movements, startle, or transition from rest to activity 1
• Secondary causes to exclude: multiple sclerosis (especially relapsing-remitting type with thalamic/basal ganglia lesions), basal ganglia calcification, hypoparathyroidism 1

Critical pitfall: Do not confuse PKD with frontal lobe epilepsy - PKD patients remain fully conscious during attacks and have clear movement triggers, whereas frontal lobe epilepsy can occur during sleep and may show altered consciousness 1

Spontaneous Jerky Movements: Chorea

If movements are continuous, random, flowing, and not triggered by specific actions:

Diagnostic Approach for Chorea

• Order MRI brain without contrast as the initial imaging study - this is the optimal modality to identify structural causes and assess for Huntington's disease changes 1
• Look for progressive caudate atrophy with frontal horn enlargement and abnormal T2 signal in putamen/caudate 1
• Obtain genetic testing for Huntington's disease (CAG repeat analysis) with appropriate genetic counseling - this is the definitive diagnostic test 1
• Exclude secondary causes: cerebrovascular disease, autoimmune conditions (SLE, antiphospholipid syndrome), thyrotoxicosis, drug-induced (dopamine blockers, stimulants), Wilson's disease 3, 4

Treatment for Chorea

For symptomatic treatment of chorea, VMAT2 inhibitors (tetrabenazine, deutetrabenazine, or valbenazine) are the treatment of choice. 5, 6

Tetrabenazine dosing protocol (FDA-approved for Huntington's chorea):

• Start at 12.5 mg daily 5
• Titrate upward weekly in 12.5 mg increments until adequate symptom control or side effects occur 5
• Maximum dose 100 mg/day (doses >50 mg/day require CYP2D6 genotyping) 5
• Divide total daily dose into 2-3 administrations 5

Critical contraindications and warnings for tetrabenazine:

• Absolute contraindications: Active depression, suicidal ideation, liver disease, concurrent MAOI use 5
• Black box warning: Can cause depression and suicidal thoughts - monitor closely for mood changes, especially during dose titration 5
• Common side effects: Sedation, parkinsonism, akathisia, difficulty swallowing 5
• Avoid alcohol (potentiates sedation) and do not drive until effects are known 5

Brief, Shock-Like Jerks: Myoclonus

If movements are very brief (fraction of a second), shock-like muscle contractions:

• Clonazepam 0.5-1 mg at bedtime is the most effective first-line treatment for most forms of myoclonus 2
• Beneficial effects typically observed within the first week 2
• Distinguish from epileptic myoclonus by obtaining EEG if seizures are suspected 2, 7
• Post-hypoxic myoclonus (after cardiac arrest) has poor prognosis but some patients can recover with treatment 2, 7

Special consideration for infants (4-7 months): If myoclonic jerks occur in clusters during wakefulness with preserved consciousness and normal development, consider benign myoclonus of early infancy - this requires no treatment and resolves spontaneously by age 2 years 8

Psychogenic Movement Disorders

If movements have variability between episodes, distractibility, and adult onset with atypical features:

• Look for red flags: altered responsiveness during attacks, additional unexplained somatic symptoms, suggestibility 1
• Candid but sympathetic discussion of the diagnosis may be beneficial 1
• Consider cognitive behavioral therapy as treatment 1
• Functional movement disorders should not receive mobility aids or equipment as this reinforces maladaptive patterns 1

Key Clinical Pitfalls to Avoid

• Do not assume all jerky movements are seizures - most movement-induced or choreiform movements occur with preserved consciousness and normal EEG 1, 7
• Do not start tetrabenazine without screening for depression - this is contraindicated and carries a black box warning for suicide risk 5
• Do not miss secondary causes - always exclude structural lesions (MRI), metabolic causes (thyroid, calcium, Wilson's disease), and drug-induced causes before assuming primary movement disorder 1, 3
• Do not confuse hyperekplexia (startle-induced stiffening from birth) with PKD - hyperekplexia presents from birth with excessive startle to auditory stimuli 1