Sydenham's chorea and seizures. Clinical and electroencephalographic studies.

The hospital records of 28 children (mean age, 9.4 years) with typical Sydenham's chorea were reviewed. Nineteen of 28 patients had antistreptolysin O titers of greater than or equal to 200 Todd units. Other causes of chorea were excluded by appropriate laboratory and clinical follow-up studies. At the onset of the movement disorder, 17 of 28 patients had abnormal EEGs consisting of irregular posterior slowing in 15, sharp epileptic spikes in 5, and high-voltage sharp waves in 2. Two patients with spikes predominantly in the temporal lobe regions developed complex partial seizures. On follow-up evaluation, the EEGs returned to normal within one to four weeks. Seizures did not recur after therapy with anticonvulsants. Seizures have been reported only rarely in association with Sydenham's chorea. Our observation suggests that seizures may occur during chorea but may often be masked by frequent choreic movements and thus not recognized. The EEG changes and seizures were transient in our patients studied so far.