Delayed-onset hemidystonia and chorea following contralateral infarction of the posterolateral thalamus - A case report

A 68 year-old man developed progressive hemidystonia and chorea 8 months after a contralateral thalamic stroke. The neurological examination also showed a right pyramidal syndrome without hemiparesis, a right horizontal sectoranopia, and a right hemihypesthesia for all sensory modalities. The MRI revealed infarctions in the left medial temporo-occipital lobes and left posterolateral thalamus, corresponding to the vascular territories of both the thalamogeniculate and posterolateral choroidal arterial pedicles. The thalamic lesion involved the pulvinar, the lateral geniculate body, and the ventro-postero-lateral, dorso-lateral, posterolateral,and dorso-medial nuclei, but apparently did not extent to the ventrolateral thalamic nucleus, and the subthalamic and midbrain regions. Thalamic and striatopallidal dystonia have not a common pathophysiological mechanism. The involvement of the pulvinar nucleus and of the strategic crossing of proprioceptive, cerebellar pyramidal, and subthalamic pathways may play a role in the genesis of the posterolateral thalamic dystonia.