Chorea is associated with a large number of hereditary or systemic diseases. This discussion focuses on chorea that arises secondary to medical diseases. Chorea consists of involuntary, irregular movements that may either take on a "worm-like" appearance called athetosis or a more proximal flinging movement called ballismus.
Stroke. Chorea is the most common movement disorder to occur as a result of stroke. In a series of 1500 patients with stroke, 4% developed movement disorders; of that 4%, chorea accounted for a third. There are several interesting features of the patients who developed chorea following stroke: compared with patients who developed other movement disorders, patients with stroke-induced chorea were older and had the shortest time interval between stroke and development of the movement disorder. Chorea caused by stroke is usually unilateral, called hemichorea, and occurs contralateral to the side of the stroke. Thalamic lesions are the most common localization of stroke-induced chorea. The majority of patients (75%) improve partially or fully by 1 year.
Postpump Chorea. Chorea can occur in children after cardiac surgery, often called postpump chorea. Most cases are mild and resolve; however, more severe forms can be life-threatening. These severe cases are associated with older age and preoperative cyanosis. It is not known whether chorea results from hypoxia, hypothermia, or the combination of both factors.
Polycythemia Vera. Polycythemia vera is often categorized as a vascular cause of chorea, although the exact mechanism of action is not known. Chorea usually occurs acutely or subacutely and may often precede the hematologic changes. It is most common in elderly females, even though polycythemia vera is more common in men. This discrepancy suggests that multiple factors underlie the pathophysiology of chorea in these patients. Chorea occurs in only 1 to 5% of patients with polycythemia vera and improves with phlebotomy.
Autoimmune mechanisms account for several types of acquired chorea.
Sydenham's Chorea. Sydenham's chorea occurs in 25% of cases of acute rheumatic fever. Chorea develops weeks to months after infection with group A ß-hemolytic streptococcus. The onset of chorea can be delayed by up to 6 months after infection. Chorea can be accompanied by facial grimacing, dysarthria, gait disturbance, and hypometric saccades. The average age of onset is 9 years. Girls are more often affected than boys. Remission occurs in half the patients by 6 months, but mild chorea may persist for years. It has also been suggested that changes in attention and behavior such as learning disabilities, obsessive compulsive disorder, and tics are more common in patients with a history of Sydenham's disease, although this is controversial.
The mechanism of action of chorea in Sydenham's chorea is thought to be cross-reactivity between antibodies to group A ß-hemolytic streptococcus and the basal ganglia. In fact, antibasal ganglia antibodies have been identified as sensitive and specific markers of Sydenham's chorea. Volumetric MRI shows enlargement of the basal ganglia in affected patients without other abnormalities. Pathology shows inflammation and neuronal loss in the basal ganglia.
Patients with Sydenham's chorea and rheumatic fever require treatment with penicillin for acute pharyngitis followed by chronic penicillin prophylaxis for 10 years. A randomized controlled trial of prednisone 2 mg/kg/d for 4 weeks followed by a taper showed that treatment with steroids improved chorea and shortened the time to remission. If symptomatic, chorea can be treated with valproic acid, carbamazepine, or haloperidol; however, some suggest that patients with Sydenham's chorea may be more susceptible to drug-induced parkinsonism.
Systemic Lupus Erythematosus. Other systemic autoimmune diseases are rare causes of chorea. Chorea occurs in ~1% of patients with systemic lupus erythematosus and usually is associated with the antiphospholipid antibody syndrome. Antibody-related pathophysiology may underlie these conditions.
Oral Contraceptives. Chorea has been attributed to use of oral contraceptive pills (OCPs). Several lines of evidence suggest that estrogen enhances central dopaminergic sensitivity. However, it is not known whether OCPs alone are sufficient to cause chorea because many patients with chorea on OCPs had coexisting antiphospholipid antibody syndrome, lupus, or prior rheumatic fever. Positron emission tomography (PET) imaging of a patient with OCP-associated chorea showed contralateral caudate hypermetabolism, suggesting that in this condition chorea is not due to a lesional effect.
Chorea Gravidarum. Chorea gravidarum may share a similar mechanism of action to that of OCP-associated chorea. It usually begins in the first trimester of pregnancy and improves later in pregnancy or after delivery.
Paraneoplastic chorea is most often associated with anti-CRMP-5 antibodies in small-cell lung cancer. The majority of these patients have other paraneoplastic neurological signs, including vision loss, neuropathy, ataxia, limbic encephalitis, elevated cells and protein concentration in cerebrospinal fluid (CSF), and T2 and fluid-attenuated inversion recovery (FLAIR) lesions on MRI. Chorea improves with cancer treatment and steroids. Paraneoplastic chorea has been reported in several other malignancies and in some cases can be refractory to medical treatment.
Disorders of Metabolism
Glucose Metabolism. Nonketotic hyperglycemia-induced chorea has several interesting features. It occurs more often in women and usually is associated with very high blood glucose (average 481 mg/dL). Nearly all patients recover fully by 6 months. All cases have MRI changes in the putamen with high signal intensity on T1-weighted imaging (Figure 2). The etiology of the MRI changes is not fully understood, but most resolve on follow-up, suggesting a reversible process such as petechial hemorrhage (not calcification); however, rare pathological reports show gliosis without hemorrhage. A study evaluating single-photon emission computed tomography (SPECT) scans in patients with nonketotic hyperglycemia-induced chorea documented striatal hypometabolism compared with patients without chorea who had the same level of hyperglycemia. Hypoglycemia-induced chorea has also been reported.
T1-weighted magnetic resonance imaging of the brain in a patient with left-sided hemichorea and nonketotic hyperglycemia demonstrates right putaminal hyperintensity.
Thyroid Disease. Hyperthyroidism is a rare metabolic cause of chorea. It is thought to result from enhanced catecholamine effects in the striatum, and can occur with thyroid replacement therapy. When chorea occurs with Hashimoto's thyroiditis, it is usually in the setting of Hashimoto's encephalopathy. Chorea due to hyperthyroidism improves with treatment of hyperthyroidism, although it may persist for weeks after thyroid levels are normalized. Symptomatic treatment with propranolol is also effective.
Renal Failure. Uremia has been associated with the sudden onset of chorea. Patients with diabetes and end-stage renal disease who develop chorea have MRI changes in basal ganglia consistent with vasogenic edema. Treatment with more frequent dialysis leads to resolution of the chorea.
Inborn Errors of Metabolism. Several inborn errors of metabolism can cause chorea but usually include a mix of different movement disorders.
Dopamine Receptor Antagonists. Tardive dyskinesia occurs after exposure to dopamine receptor antagonists. Most characteristically, patients develop oral-lingual-buccal movements, although chorea may affect the limbs and the trunk as well. Of particular relevance to medical conditions is the fact that metoclopramide, a dopamine antagonist, can cause tardive syndromes.
Other Drugs. A variety of drugs have been reported to cause chorea. Those of special importance in internal medicine include cimetidine, digoxin, isoniazid, verapamil, and theophylline. Others include baclofen, tricyclic antidepressants, steroids, and antiepileptics. Chorea can also develop from abuse of cocaine and amphetamines.
Semin Neurol. 2009;29(2):97-110. © 2009 Thieme Medical Publishers
Cite this: Movement Disorders Caused by Medical Disease - Medscape - Apr 15, 2009.