Sydenham's chorea

Definition

Sydenham's chorea is an acute but self-limited movement disorder that occurs most commonly in children between the ages of five and 15, and occasionally in pregnant women. It is closely associated with rheumatic fever following a throat infection. The disorder is named for Thomas Sydenham (1624–1689), an English doctor who first described it in 1686. Other names for Sydenham's chorea include simple chorea, chorea minor, acute chorea, rheumatic chorea, juvenile chorea, and St. Vitus' dance. The English word chorea itself comes from the Greek word choreia, which means "dance." The disorder takes its name from the rapid involuntary jerking or twitching movements of the patient's face, limbs, and upper body.

Description

Sydenham's chorea is best described as a neurologic complication of rheumatic fever triggered by a throat infection (pharyngitis) caused by particular strains of bacteria known as group A beta-hemolytic streptococci or as GAS bacteria. In general, streptococci are sphericalshaped anaerobic bacteria that occur in pairs or chains. GAS bacteria belong to a subcategory known as pyogenic streptococci, which means that the infections they cause produce pus.

The initial throat infection that leads to Sydenham's chorea is typically followed by a symptom-free period of one to five weeks. The patient then develops an acute case of rheumatic fever (ARF), an inflammatory disease that affects multiple organ systems and tissues of the body. In most patients, ARF is characterized by fever, arthritis in one or more joints, and carditis, or inflammation of the heart. In about 20% of patients, however, Sydenham's chorea is the only indication of ARF. Sydenham's is considered a delayed complication of rheumatic fever; it may begin as late as 12 months after the initial sore throat, and it may start only after the patient's temperature and other physical signs have returned to normal. The average time interval between the pharyngitis and the first symptoms of Sydenham's, however, is eight or nine weeks.

It is difficult to describe a typical case of Sydenham's chorea because the symptoms vary in speed of onset as well as severity. Most patients have an acute onset of the disorder, but in others, the onset is insidious, which means that the symptoms develop slowly and gradually. In some cases, the child's physical symptoms are present for four to five weeks before they become severe enough for the parents to consult a doctor. In other cases, emotional or psychiatric symptoms precede the clumsiness and involuntary muscular movements that characterize the disorder. The psychiatric symptoms that may develop in patients with Sydenham's chorea are one reason why it is sometimes categorized as a PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) disorder.

Demographics

Both ARF and Sydenham's chorea are relatively un-common disorders in the United States. According to the Centers for Disease Control and Prevention (CDC), only 1–3% of people with streptococcal throat infections develop ARF; thus, the incidence of ARF in the United States is thought to be about 0.5 per 100,000 patients between five and 17 years of age.

In general, the incidence of Sydenham's chorea is lower in the developed countries than in others, largely because of the widespread use of antibiotics in these countries to treat childhood streptococcal infections in the 1960s and 1970s. In addition, the disorder appears to have been overdiagnosed in the past; whereas at one time doctors thought that as many as half of all patients with ARF developed Sydenham's, present reports estimate that about 26% of ARF patients develop chorea. On the other hand, however, there are signs that the incidence of rheumatic fever is rising again in the United States and Canada; since the late 1980s, outbreaks have been reported at military installations in California and Missouri as well as in various cities in Pennsylvania, Utah, and Ohio. It is thought that this increase is due to more virulent strains of group A streptococci.

With regard to age, the incidence of Sydenham's chorea is higher in childhood and adolescence than in adult life. It occurs more frequently in females than in males; the gender ratio is thought to be about two females to one male. Since the peak incidence of rheumatic fever in North America occurs in late winter and spring, Sydenham's chorea is more likely to occur in the summer and early fall. There is no evidence that the disorder selectively affects specific racial or ethnic groups.

About 20% of patients diagnosed with Sydenham's chorea experience a recurrence of the disorder, usually within two years of the first episode. Most women who develop Sydenham's during pregnancy have a history of ARF in childhood or of using birth control pills containing estrogen.

Causes and symptoms

The basic cause of Sydenham's chorea is infection with GAS bacteria, which are usually transmitted from person to person through large droplets produced by coughing or sneezing, or by direct contact. GAS bacteria can also be transmitted through contaminated food, most commonly eggs, milk, or milk products. The bacteria then invade the patient's upper respiratory tract, producing the sore throat that precedes the movement disorder.

The next stage in the development of Sydenham's chorea is an abnormal response of the patient's immune system to the streptococcal infection. Streptococcal antigens resemble nerve tissue antigens. In some people, the immune system produces antibodies against the streptococcal antigens that then cross-react against the tissues in certain regions of the brain—specifically, areas of the brain known as the basal ganglia. The basal ganglia are paired clusters of nerve cells that lie deep within the brain; they serve to regulate a person's movements, although they also play a role in governing emotions and certain aspects of thinking. Magnetic resonance imaging (MRI) studies of patients with Sydenham's chorea indicate that the basal ganglia are abnormally large, suggesting that they have been affected by the inflammation caused by the infection.

Some people are at greater risk of developing Sydenham's chorea. The risk factors for the disorder include:

Living in crowded living conditions, inadequate sanitation, and malnutrition. Streptococcal infections are most common among the poor or homeless.
Genetic factors. Some families appear to be more susceptible to ARF, although no specific genes have been identified.

Female gender. Some researchers think there is a link between female sex hormones and susceptibility to Sydenham's, given that girls are more likely than boys to develop the disorder, particularly during puberty. In addition, women who are pregnant or have taken birth control pills containing estrogen are more likely to have recurrences of Sydenham's. The disorder is virtually un-known in sexually mature males.

PHYSICAL SYMPTOMS Although the speed of onset varies, patients with Sydenham's chorea develop rapid and purposeless involuntary motions or gestures that may involve all the muscles of the body, except those around the eyes. Most patients are affected on both sides of the body; however, about 20% have symptoms on only side of the body, a condition called hemichorea. The movements disappear during sleep, but usually become more severe when the child is tired or under stress. The patient's intentional movements such as picking up objects or writing by hand may become clumsy or uncoordinated; in addition, the muscles may become generally weak or lose their tone. In milder cases of Sydenham's, the patient may have only facial grimacing and some difficulty putting on clothes or doing other tasks that require fine coordination. In more severe cases, however, the patient's life may be disrupted by movements that affect large groups of muscles, preventing the patient from walking, going to school, or doing most daily activities.

PSYCHIATRIC SYMPTOMS As has been mentioned earlier, some children develop psychiatric symptoms associated with Sydenham's chorea before the physical symptoms appear. They may start acting unusually restless, aggressive, or hyperemotional. Behavioral or emotional disturbances that have been observed with the disorder include:

frequent mood changes
episodes of uncontrollable crying
behavioral regression, that is, acting like much younger children
mental confusion
general irritability
difficulty concentrating
impulsive behavior

The most common psychiatric syndrome observed in children with Sydenham's chorea, however, is obsessive-compulsive disorder (OCD). OCD is characterized by obsessions, which are unwanted recurrent thoughts, images, or impulses, and by compulsions, which are repetitive rituals, mental acts, or behaviors. Obsessions in children often take the form of fears of intruders or harm coming to a family member. Compulsions may include such acts as counting silently, washing the hands over and over, insisting on keeping items in a specific order, checking repeatedly to make sure a door is locked, and similar behaviors.

Diagnosis

The diagnosis of Sydenham's chorea is usually based on a combination of a recent history of a streptococcal infection and the doctor's observation of the patient's involuntary movements. Unlike tics, the movements associated with chorea are not repetitive, and unlike the behavior of hyperactive children, the movements are not intentional. The recent onset of the movements rules out a diagnosis of cerebral palsy. If Sydenham's is suspected, the physician may ask the patient to stick out the tongue and keep it in that position, or to squeeze the doctor's hand. Many patients with Sydenham's cannot hold their mouth open and keep the tongue out for more than a second or two. Another characteristic of Sydenham's is an inability to grip with a steady pressure; when the patient squeezes the doctor's hand, the strength of the grip will increase and decrease in an erratic fashion. This characteristic is sometimes called the "milking sign."

Although imaging studies are used by researchers to study Sydenham's chorea, they are not ordinarily used by themselves to diagnose the disorder. Blood tests may show elevated levels of antibodies against streptococcal bacteria, or the patient's throat culture may be positive, but more often these tests give negative results by the time the movement disorder develops.

Once the diagnosis has been made, the doctor will evaluate the patient's heart for any indications of damage caused by rheumatic fever. This evaluation includes listening for abnormal heart sounds through a stethoscope and taking x rays to determine whether the heart is enlarged. In some cases, the doctor may order an electrocardiogram (EKG) to assess any irregularities in the patient's heartbeat.

Treatment team

In most cases, a child with Sydenham's chorea will be examined and diagnosed by a pediatrician. A child or adolescent psychiatrist may be consulted if the patient has developed symptoms of OCD. Children with heart murmurs or other signs of carditis may be referred to a pediatric cardiologist for further evaluation.

Treatment

Adequate treatment of a streptococcal throat infection with antibiotics may help to prevent an attack of ARF or Sydenham's chorea.

If the chorea has already developed, most doctors do not advise treating the involuntary movements by themselves unless they are so severe that the child is disabled or at risk of self-injury. The reason for this precaution is that some of the recommended drugs, which are known as dopamine antagonists or neuroleptics, have potentially severe side effects. Dopamine antagonists include such medications as haloperidol (Haldol), risperidone (Risperdal), and pimozide (Orap). Some doctors may prescribe an anticonvulsant (antiseizure) drug, most commonly sodium valproate (Depakene), to lower the risk of injury. If the patient does not respond to the anticonvulsant, the child may be prescribed the lowest effective dose of a neuroleptic. Some doctors may prescribe a benzodiazepine tranquilizer like diazepam (Valium) or lorazepam (Ativan) to control the movements. Another type of drug that appears to help some patients with Sydenham's is corticosteroids, which are given to lower the inflammation associated with ARF.

Most doctors recommend ongoing treatment with penicillin to prevent a recurrence of ARF or Sydenham's chorea, although there is some disagreement as to whether this treatment should continue for five years after an acute attack or for the rest of the patient's life. The penicillin may be given orally or by injection. Patients who cannot take penicillin may be given erythromycin or sulfadiazine.

Obsessive-compulsive disorder is treated with a combination of psychotherapy (usually cognitive behavioral therapy, or CBT) and medications (usually selective serotonin reuptake inhibitors or SSRIs).

Recovery and rehabilitation

Most patients with Sydenham's chorea recover after a period of bed rest and temporary limitation of normal activities. In most cases, the symptoms disappear gradually rather than stopping abruptly.

Clinical trials

As of early 2004, the National Institute of Mental Health (NIMH) is recruiting subjects for a study of magnetic resonance imaging (MRI) in assessing brain structure and function in patients with childhood-onset psychiatric disorders. Sydenham's chorea, as well as other PANDAS disorders, is one of the conditions included in the study.

Prognosis

Sydenham's chorea is a self-limiting disorder that usually runs its course within one to six months, although it occasionally lasts as long as one to two years. In most cases, the patient recovers completely, although the disorder may recur. In a very few cases—about 1.5% of patients diagnosed with Sydenham's—there may be increasing muscle stiffness and loss of muscle tone resulting in disability. This condition is occasionally referred to as paralytic chorea.

Special concerns

Many doctors recommend that children with Sydenham's chorea should not be kept out of school longer than is necessary. Some of the psychological side effects that were once thought to be caused by the chorea itself are now regarded as the result of missing school combined with worry about other people's reactions to the involuntary movements.

Resources

BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision. Washington, DC: American Psychiatric Association, 2000.

Martin, John H. Neuroanatomy: Text and Atlas, 3rd ed. New York: McGraw-Hill, 2003.

"Sydenham's Chorea (Chorea Minor; Rheumatic Fever; St. Vitus' Dance)." Section 19, Chapter 271 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2002.

PERIODICALS

Arnold, P. D., and M. A. Richter. "Is Obsessive-Compulsive Disorder an Autoimmune Disease?" Canadian Medical Association Journal/Journal de l'association médicale canadienne 165 (November 13, 2001): 1353–1358.

Bonthius, D. J., and B. Karacay. "Sydenham's Chorea: Not Gone and Not Forgotten." Seminars in Pediatric Neurology 10 (March 2003): 11–19.

Cardoso, F., D. Maia, M. C. Cunningham, and G. Valenca. "Treatment of Sydenham Chorea with Corticosteroids." Movement Disorders 18 (November 2003): 1374–1377.

Caviness, John M., MD. "Primary Care Guide to Myoclonus and Chorea." Postgraduate Medicine 108 (October 2000): 163–172.

Church, A. J., F. Cardoso, R. C. Dale, et al. "Anti-Basal Ganglia Antibodies in Acute and Persistent Sydenham's Chorea." Neurology 59 (July 23, 2002): 227–231.

Herrera, Maria Alejandra, MD, and Nestor Galvez-Jiminez, MD. "Chorea in Adults." eMedicine 1 February 2002 (April 27, 2004). <http://www.emedicine.com/neuro/topic62.htm>.

Snider, L. A., and S. E. Swedo. "Post-Streptococcal Autoimmune Disorders of the Central Nervous System." Current Opinion in Neurology 16 (June 2003): 359–365.

OTHER

American Academy of Child and Adolescent Psychiatry (AACAP). AACAP Facts for Families, No. 60. Obsessive-Compulsive Disorder in Children and Adolescents. (April 27, 2004). <http://www.aacap.org/publications/factsfam/ocd.htm>.

National Institute of Neurological Disorders and Stroke (NINDS). NINDS Sydenham Chorea Information Page. (April 27, 2004). <http://www.ninds.nih.gov/health_and_medical/disorders/sydenham.htm>.

ORGANIZATIONS

American Academy of Child and Adolescent Psychiatry (AACAP). 3615 Wisconsin Avenue NW, Washington, DC 20016-3007. (202) 966-7300; Fax: (202) 966-2891. <http://www.aacap.org>.

National Institute of Neurological Disorders and Stroke (NINDS). 9000 Rockville Pike, Bethesda, MD 20892. (301) 496-5751 or (800) 352-9424. <http://www.ninds.nih.gov>.

National Organization for Rare Disorders (NORD). P. O. Box 1968, Danbury, CT 06813-1968. (203) 744-0100 or (800) 999-NORD; Fax: (203) 798-2291. orphan@rarediseases.org. <http://www.rarediseases.org>.

WE MOVE—Worldwide Education and Awareness for Movement Disorders. 204 West 84th Street, New York, NY 10024. (212) 875-8389 or (800) 437-MOV2. wemove@wemove.org. <http://www.wemove.org>.