Pure hemi-chorea resulting from an acute phase of contralateral thalamic lacunar infarction: a case report.

BACKGROUND: Thalamic lesions give rise to a variety of clinical syndromes such as pure sensory stroke, ataxic hemiparesis, and rarely involuntary movements including chorea. Generally and classically, lacunar infarction in the subthalamic nucleus has been regarded as the lesion mainly responsible for hemi-chorea and hemi-ballismus, on the basis of previous anatomical studies.

CASE PRESENTATION: This report describes the case of an 81-year-old man who developed sudden-onset pure hemi-chorea in the right limbs resulting from an acute phase of left thalamic lacunar infarction detected on a diffusion-weighted image (DWI) in an MRI study. The patient had no other neurological symptoms such as ataxic hemiparesis and sensory disturbance. A single-photon emission computed tomography (SPECT) study using the (99m)Tc-ECD Patlak plot method demonstrated significant perfusional asymmetry between the right and left thalami (p = 0.0035), consistent with the left thalamic lesion on DWI.

CONCLUSION: It is speculated that this perfusional asymmetry, in particular the hypoperfusion in the left thalamus, detected by SPECT might play the most important role in the contralateral pure hemi-chorea as a rare neurological manifestation in this case.