Clinical-metabolic correlation between parkinsonian syndromes:an FDG-PET study.

Objectives Positron emission tomography (PET) imaging with F-18 fluorodeoxyglucose (FDG) has recently assumed a greater role in evaluation of neuronal and synaptic dysfunction in several neurodegenerative parkinsonisms. The present study aims to identify the characteristic patterns of regional glucose metabolism in patients with neurodegenerative parkinsonisms and the metabolic correlation with clinical symptoms.

Methods 81 patients with neurodegenerative parkinsonism (54 with Parkinson’s disease-PD,11 with multiple system atrophy-MSA,9 with progressive supranuclear palsy-PSP,and 7 with corticobasal syndrome-CBS) underwent FDG-PET examinations. PET scans of each group of patients were compared with a group of normal controls and with each other, using Statistical Parametrical Mapping (SPM). In each group of patients,correlations with different clinical symptoms were analyzed.

Results SPM analysis demonstrated that glucose metabolic reductions occurred in several parieto-temporo-occipital regions in PD,in putamen bilaterally in MSA,in medial frontal,anterior cingulate cortices,caudate nuclei and mesencephalon in PSP,and in cortical (frontal and parietal) and sub-cortical (striata and thalami) regions of one hemisphere in CBS patients. The direct comparison between groups highlighted specific brain regions of major metabolic differences between patients. In each group of patients correlation with different specific clinical symptoms have been found.

Conclusions Specific metabolic phenotypes have been demonstrated in different neurodegenerative parkinsonisms, such as PD, MSA, PSP and CBS,with specific correlations with clinical symptoms. FDG-PET imaging may contribute to early and accurate differential diagnosis in neurodegenerative parkinsonisms.