Crossed hemispheric diaschisis in unilateral cerebellar lesions

We studied 12 patients with unilateral cerebellar hemorrhage to look at its effect on regional cerebral blood flow.

We used single-photon emission computed tomography by continuous inhalation of xenon-133. The blood flow was quantified in the cerebellum and in nine areas of interest on the slice passing through the basal ganglia.

The comparison of the blood flow values of the patients and control subjects showed a significant reduction in the contralateral hemisphere of the patients, predominantly in the frontal region and in the lenticular nucleus of the contralateral hemisphere but also in the anterointernal frontal area of the ipsilateral hemisphere. The analysis of the asymmetry indexes revealed in the same way significant differences between patients and control subjects in the frontal cortex and in the lenticular nucleus.

These results provided concordant evidence suggesting a blood flow reduction in the contralateral hemisphere. This phenomenon of "crossed hemispheric diaschisis" is probably related to the interruption of cerebellocortical tracts.