TOMOGRAPHIC MEASUREMENTS OF REGIONAL CEREBRAL BLOOD-FLOW IN PROGRESSIVE SUPRANUCLEAR PALSY AND PARKINSONS-DISEASE

Intellectual changes observed in progressive supranuclear palsy (PSP) are sometimes seen with lesser intensity in Parkinson's disease (PD). Cognitive impairment of PSP has been attributed to a frontal lobe dysf unction explaining the frontal cortex hypometabolism detected by PET. To establish whether this frontal hypometabolism is more pronounced in PSP than in PD, we compared frontal and temporo-parietal cerebral blo od flow (CBF) indexes studied by SPECT using Tc99m HmPAO in 18 PSP, 18 PD and 8 control subjects. For each patient neuropsychological perfor mances were also assessed. A significant left frontal hypoperfusion wa s observed in PSP (mean index value: 0.78 +/- 0.03, p<0.01) and PD (0. 78 +/- 0.04, p<0.05) as compared to controls (0.84 +/- 0.03), whereas there was no difference between PSP and PD. No correlation was discove red between neuropsychological performances and frontal cortical index changes. This frontal uptake reduction of Tc99m HmPAO in PSP and PD c ould result from a disconnection phenomenon secondary to subcortical l esions. In both groups mean frontal indexes showed only a left frontal hypoperfusion suggesting that subcortical structures might be asymmet rically involved in early stages of the diseases. The lack of differen ce for indexe values between PSP and PD might be explained by the diff erence between the mean disease duration: 4.3 years for the PSP and 7. 8 years for the PD. It might also suggest that frontal CBF reduction e xists in the same proportions in PD and PSP, but at a later stage in t he former case.