November 18, 2013
A 64-year-old man with involuntary movements in the right upper and lower extremities
Hemichorea-Hemiballismus Syndrome in Nonketotic Hyperglycemia
- Hemichorea-hemiballismus syndrome is a unilateral chorea, characterized by usually continuous, nonpatterned, involuntary movement disorder.
- The most common cause of hemiballismus is a focal vascular lesion in the contralateral basal ganglion. However, hemiballismus is frequently associated with nonketotic hyperglycemia.
- Key Diagnostic Features: Characteristic MRI findings are T1WI hyperintensity in the contralateral putamen. Variable diffusion signal (normal to restricted) has been mentioned. There is no change in the corresponding T2-weighted signal nor any abnormal enhancement. Proposed mechanisms include petechial hemorrhage, calcification, myelinolysis, and mild ischemia with gemistocyte accumulation. High attenuation in the corresponding area is often seen on CT.
- DDx: Hepatic encephalopathy
- Rx: Correction of the underlying hyperglycemia
