Corticobasal syndrome: a prospective study of clinical profiles and imaging biomarkers

Background: Corticobasal syndrome (CBS) is neurodegenerative disorder related to multiple underlying pathologies. Objective: To investigated if dividual FDG-PET patterns could distinguish CBS due to Alzheimer’s disease (AD) from other pathologies based on [11C]Pittsburgh Compound-B (PIB)-PET. Methods: Forty-five patients with probable CBS were prospectively evaluated. They underwent FDG-PET and were divided into groups: related to AD (CBS FDG-AD) or non-AD (CBS FDG-nonAD). Thirty patients underwent PIB-PET on a PET-MRI to assess their amyloid status. FDG and PIB-PET were classified individually on visual analysis, and PET-MRI quantitative group analyses were performed. Results: CBS FDG-AD group (33.3%) showed worse cognitive performances, displayed more myoclonus and hallucinations. CBS FDG-nonAD group (66.7%) presented more dystonia, ocular motor dysfunction, perseveration, and dysarthria. All CBS FDG-AD patients tested positive at PIB-PET compared to 3 out of 20 in the non-AD group. The individual FDG-PET classification had 76.92% of sensitivity, 100% of specificity and 88.5% of accuracy to detect positive PIB-PET scans. Individuals with positive and negative PIB-PET showed hypometabolism in temporoparietal areas and in thalamus and brainstem, respectively, disclosing metabolic signatures. Conclusion: CBS is mainly distinguished by two variants (AD and non-AD), with different cognitive profiles and possibly motor features. FDG-PET was useful depicting their specific degeneration patterns and brain amyloid deposition.