Hemiballismus

Hemiballismus is a rare hyperkinetic movement disorder of sudden, violent, large amplitude, flinging movements of the arm and leg on one side of the body, usually caused by a lesion of the contralateral subthalamic nucleus or its connections. Ballismus involving one limb is monoballismus.

The incidence is under 1 in 500,000 people each year. It most often affects older adults with stroke, and men and women are equally affected. It makes up about 1% of movement disorders after stroke.

Causes. Ischaemic or haemorrhagic stroke (commonest), non-ketotic hyperglycaemia in diabetes, tumour, abscess, toxoplasmosis in HIV, demyelination, trauma, vascular malformations and, rarely, drugs.

Course. Many cases improve over weeks to months, and often settle spontaneously; severe persistent cases can cause exhaustion, dehydration, rhabdomyolysis and skin injury.

Pathophysiology.

Loss of the excitatory output from the subthalamic nucleus reduces inhibition from the globus pallidus internus, so the thalamus and motor cortex are over stimulated.

The result is uncontrolled proximal limb movement on the opposite side.

• Abrupt, wild, high amplitude flinging, throwing or rotatory movements of the proximal limbs on one side, continuous while awake and stopping in sleep.
• Often accompanied by chorea of the distal limb (hemichorea hemiballismus).
• Risk of self-injury, bruising, exhaustion, weight loss and sleep loss.
• Possible weakness or other stroke signs, or hyperglycaemic features.

Red flags.

• Acute onset with weakness, speech disturbance or reduced consciousness (stroke).
• Severe hyperglycaemia or diabetic ketoacidosis.
• Rhabdomyolysis (dark urine, raised creatine kinase), dehydration or exhaustion.
• Fever, immunosuppression or HIV (infection).

• Clinical diagnosis from the movement pattern.
• Urgent brain imaging: CT to exclude haemorrhage, then MRI with diffusion weighted imaging; contrast imaging for tumour or infection.
• Blood glucose, HbA1c, electrolytes, renal function, creatine kinase, calcium, thyroid function, HIV test, autoimmune tests and toxicology.
• Vascular imaging when stroke is found; further tests for mass lesions.
• Assess hydration, injury and nutrition.

Differential diagnosis. Hemichorea due to non-ketotic hyperglycaemia, Huntington disease, Sydenham chorea, tardive dyskinesia, focal seizures, athetosis, dystonia and functional movement disorder.

• Treat the cause: stroke care, glucose correction, treat infection or tumour, stop causative drugs.
• Protect from injury with padding and rails, maintain fluids and nutrition, and treat exhaustion.
• Haloperidol: 0.5 mg orally twice daily, increased by 0.5 mg every 3 days to a usual 3 to 10 mg daily in 2 to 3 divided doses. Maximum 20 mg daily. Monitor QT interval (ECG at baseline and after increases), potassium, magnesium, sedation and extrapyramidal effects. Avoid in Parkinson disease, QT prolongation, recent myocardial infarction and with other QT-prolonging drugs; use lower doses in older adults and hepatic impairment; avoid in pregnancy unless needed.
• Tetrabenazine: 12.5 mg orally once daily, increased by 12.5 mg each week to a usual 25 to 75 mg daily in 2 to 3 divided doses. Maximum 100 mg daily without CYP2D6 genotyping. Monitor depression, suicidal thoughts, parkinsonism and QT interval. Contraindicated in depression with suicidal thoughts, hepatic impairment and with monoamine oxidase inhibitors; avoid in pregnancy.
• Sodium valproate as an alternative: 600 mg orally daily in 2 divided doses, increased by 200 mg every 3 days to 1000 to 2000 mg daily. Maximum 2500 mg daily. Monitor liver function, full blood count and platelets. Avoid in liver disease, mitochondrial disease and urea cycle disorders; contraindicated in girls and women of childbearing potential unless a pregnancy prevention programme is in place.
• Hyperglycaemic hemichorea: insulin and fluids by the usual diabetic emergency approach.
• Stereotactic pallidotomy or deep brain stimulation for severe, refractory cases.
• Physiotherapy and occupational therapy during recovery.

Monitoring. Review at 1 to 2 weeks, then monthly; track movement severity, fluids, creatine kinase and drug effects; attempt to taper drugs after 3 to 6 months.

Referral and escalation. Neurology and stroke services; endocrinology for hyperglycaemia; neurosurgery for refractory disease; intensive care for exhaustion or rhabdomyolysis.

Special groups. Older adults: use low doses of haloperidol because of sedation and QT risk. Diabetes: tight glycaemic control.