SYDENHAM DISEASE AND OTHER CHILDHOOD CHOREAS
In 1686, Thomas Sydenham described the chorea now known by his name but originally called St. Vitus dance. His description was of children with a halting gait and jerky movements. Sydenham disease (acute chorea, St. Vitus dance, chorea minor, rheumatic chorea) is a disease of childhood characterized by chorea, which is often asymmetric or may be unilateral (hemichorea) in about 20% of the cases (Video 81.1). The abnormal movements give the child a restless appearance. The chorea, with some exceptions, is self-limited and fatalities are rare except as a result of cardiac complications. Because chorea is only one of many manifestations, including a variety of neurologic, psychiatric, cardiac, rheumatologic, and other problems, the term Sydenham disease is more appropriate than calling the disorder Sydenham chorea, an earlier term.
ETIOLOGY AND PATHOBIOLOGY
Sydenham disease is considered an autoimmune disorder, a consequence of infection with group A β-hemolytic Streptococcus. Unlike arthritis and carditis, which occur soon after the infection, chorea may be delayed for 6 months or longer. The Streptococcus is thought to induce antibodies that cross-react with neuronal cytoplasmic antigens of caudate and subthalamic nuclei, which apparently account for the symptoms characteristic of rheumatic chorea. These antineuronal antibodies are found in the serum of nearly all patients with Sydenham disease. Antibodies to cardiolipin, which have been found in chorea associated with lupus erythematosus, have not been found in Sydenham chorea. Postmortem changes in rare fatal cases that came to autopsy can be attributed to embolic phenomena due to associated carditis. A mild degree of inflammatory reaction has been found in a few patients.
Knowledge of the etiology and immunology of Sydenham chorea has spawned the concept of other pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) and pediatric acute-onset neuropsychiatric syndrome (PANS). There is, however, considerable debate among the experts about the pathophysiologic mechanisms of PANDAS and PANS and its possible relationship to other movement disorders, including tics.
INCIDENCE
The incidence of Sydenham disease had fallen dramatically with the introduction of antibiotics and with better sanitary conditions.
It now is encountered infrequently in developed countries, but it is still common in developing countries. Acute chorea is almost exclusively a disease of childhood; over 80% of the cases occur in patients between the age of 5 and 15 years. Onset of the first attack after the age of 15 years is uncommon. After spontaneous remission, some female patients have a recurrence during pregnancy, so-called chorea gravidarum, or with the use of oral contraceptives in the late teens and early 20s. All races are affected. Girls are affected more than twice as frequently as boys. The disease occurs at all times of the year but seems to be less common in summer.
CLINICAL FEATURES
In addition to the choreic movements and accompanying motor impersistence (inability to sustain certain simple voluntary acts such as protruding the tongue), Sydenham disease is associated with a variety of neurobehavioral problems, such as irritability; emotional lability; anxiety; obsessive-compulsive behavior and other neuropsychiatric manifestations; speech impairment; and, more rarely, encephalopathy, reflex changes, weakness, gait disturbance, headache, seizures, and cranial neuropathy.
The clinical features of the chorea in Sydenham disease differ from chorea in patients with Huntington disease (HD). In Sydenham, the chorea is manifested by a restless-appearing motor behavior, whereas in HD, the chorea consists of more isolated, jerky movements that become more flowing as the chorea worsens. Physiologic recordings in Sydenham chorea reveal the bursts of electromyographic (EMG) activity to last more than 100 milliseconds and to occur asynchronously in antagonistic muscles. These findings are in contrast to the chorea associated with HD, in which more frequent and shorter EMG bursts of 10 to 30 milliseconds and 50 to 100 milliseconds occur.
