Restricted unilateral Sydenham's chorea: Reversible contralateral striatalhypermetabolism demonstrated on single photon emission computed tomographic scanning

Sydenham's chorea results from group A streptococcus infection and subseque nt generation of antineuronal antibodies directed at the caudate nucleus an d putamen. Predominantly bilateral, in up to 30% of cases the chorea can be unilaterally restricted. Ima,bing studies, both structural (magnetic reson ance imaging) and functional (positron emission tomography), in patients wi th bilateral Sydenham's chorea have suggested reversible striatal abnormali ties. Two patients with unilateral Sydenham's chorea are presented. Compute d tomographic and magnetic resonance imaging were normal in both. However, hexamethylpropylenamine oxime single photon emission tomographic (HMPAO SPE CT) studies demonstrated hypermetabolism in the contralateral basal ganglia . Resolution of symptoms in one of the patients coincided with normalizatio n of the SPECT scan. Thus, unilateral striatal hypermetabolism appears to u nderlie the contralateral chorea observed. A SPECT scan probably should be included in the work-up of new-onset chorea.