Article Text

Download PDFPDF
Evidence of thalamic disinhibition in patients with hemichorea: semiquantitative analysis using SPECT
  1. J-S Kim1,
  2. K-S Lee1,
  3. K-H Lee1,
  4. Y-I Kim1,
  5. B-S Kim1,
  6. Y-A Chung2,
  7. S-K Chung2
  1. 1Department of Neurology, College of Medicine, The Catholic University of Korea
  2. 2Department of Nuclear Medicine
  1. Correspondence to:
 Dr K-S Lee, Movement Clinic, Department of Neurology, Kangnam St Mary's Hospital, 505 Banpo-Dong, Seocho-Ku, Seoul, 130–701, South Korea;


Objectives: Hemichorea sometimes occurs after lesions that selectively involve the caudate nucleus, putamen, and globus pallidus. Some reports have hypothesised that the loss of subthalamic nucleus control on the internal segment of the globus pallidus, followed by the disinhibition of the thalamus may contribute to chorea. However, the pathophysiology is poorly understood. Therefore, clinicoradiological localisation was evaluated and a comparison of the haemodynamic status of the basal ganglia and thalamus was made.

Methods: Six patients presenting with acute onset of hemichorea were assessed. Neuroimaging studies, including MRI and SPECT examinations in addition to detailed biochemical tests, were performed. A semiquantitative analysis was performed by comparing the ratio of blood flow between patients and normal controls. In addition, the ratio of perfusion asymmetry was calculated as the ratio between each area contralateral to the chorea and that homolateral to the chorea. The comparison was made with a two sample t test.

Results: The causes of hemichorea found consisted of four cases of acute stroke, one non-ketotic hyperglycaemia, and one systemic lupus erythematosus. Brain MRI indicated lesion sites in the contralateral putamen, globus pallidus, caudate nucleus, and subthalamic nucleus. A significant decrease in the ratio of blood flow in the basal ganglia contralateral to the chorea and a significant increase in the thalamus was found when comparing the perfusion asymmetries, which were calculated as the ratio of cerebral blood flow (CBF) for each region to that in the homolateral occipital area (p<0.05).

Conclusion: An alteration in CBF in both the contralateral thalamus and basal ganglia reflect the loss of pallidal inhibitory input from the pallidum to the thalamus. This change in CBF may be one of epiphenomena, which implicates an occurrence of hemichorea in humans.

  • hemichorea
  • basal ganglia
  • thalamus
  • cerebral blood flow
  • CBF, cerebral blood flow
  • GABA, γ-aminobutyric acid
  • GPe, external globus pallidus
  • GPi, internal globus pallidus

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.