Introduction: Hemichorea is uncommon in acute cerebrovascular accidents. Its appearance is in relation to the contralateral involvement of the basal ganglia, particularly the striate ganglion. With current neuroimaging techniques it is possible to identify the lesions responsible for these abnormal movements. Magnetic resonance (MR) is the technique of choice for detection of small sized lesions.
Objective: We have analysed our series of patients to try to relate the site of the lesion to the appearance of chorea.
Patients and methods: We made a retrospective study of the cases of hemichorea of vascular origin admitted between January 1993 and April 1999. In all cases, cerebral CAT and/or MR had been done to find the site of the lesion.
Results: A total of 10 patients with an average age of 72.5 years (range: 55-85) was found. In eight of them (80%) lesions were found in the basal ganglia, half of which were of ischemic type and the other half hemorrhagic. The sites were: caudate nucleus in one case (10%), thalamus in two cases (20%) and capsulo-lenticular lesions in five cases (50%). All lesions were contralateral to the side of the body affected except in one case with a left thalamic haematoma and homolateral hemichorea.
Conclusions: The lesions found were very varied in site. In 20% of the cases they were not detected by conventional neuroimaging techniques. This fact supports the concept of a functional global network of the basal ganglia which may be interrupted at several points and lead to the same clinical findings.