Objective
The aim of this study was to investigate the incidence of intrahemispheric diaschisis in subcortical lesions and relationships between involved structures and intrahemispheric diaschisis using positron emission tomography (PET).

Method
Thirty stroke patients with unilateral subcortical lesions without cortical structural abnormality were recruited. The findings of [¹⁸F]Fluoro-2-Deoxy-D-Glucose PET were interpretated by experienced radiologist.

Results
In the lesions around basal ganglia, hypometabolism of ipsilateral whole hemisphere was observed in 8 of 20 patients and ipsilateral parietal, frontal, temporal, occipital lobe was observed in order of incidence. Intrahemispheric diaschisis had a tendency to expand when the centrum semiovale was involved. Crossed cerebellar diaschisis was observed in 17 of 20 patients. In the lesions around thalamus, hypometabolism of ipsilateral whole hemisphere was observed in 6 of 8 patients, and ipsilateral frontal, temporal, parietal lobe was observed in order of incidence. Intrahemispheric diaschisis had a tendency to expand when the internal capsule was involved. Crossed cerebellar diaschisis was observed in 5 of 8 patients.

Conclusion
This study shows that intrahemispheric diaschisis was observed in all patients with subcortical lesions without cortical structural abnormality and had a tendency to expand to larger area of the cerebral cortex when the connecting fibers between cortical and subcortical structures were involved. (J Korean Acad Rehab Med 2002; 26: 495-501)