Cerebral Glucose Metabolism and Dopaminergic Function in Patients with Corticobasal Syndrome

The corticobasal syndrome (CBS) is a clinical diagnosis that comprises a group of rare neurodegenerative diseases manifesting in movement disorder and cognitive impairment. While diagnosis is based upon clinical criteria, there have been a number of molecular imaging studies, albeit in rather small cohorts. Therefore, we investigated the pattern of cerebral glucose metabolism, as well as dopamine transporter (DAT) availability in a large and clinically well-defined cohort.

Thirty-four patients fulfilling either the Armstrong or the Boeve criteria were assessed with [¹⁸ F]-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) and/or [¹²³ I]-Ioflupane single-photon-emission-computed tomography (SPECT) for DAT availability. A small subset of patients had also undergone D_2/3 receptor imaging. Imaging data were analyzed using both statistical parametric mapping and a volume-of-interest-based approach relative to data from healthy controls.

Significant reductions of the cortical glucose metabolism were observed in the central region and the adjacent frontal and parietal association areas contralateral to the side with predominant motor symptoms. Reductions were also evident in the basal ganglia, notably in the putamen contralateral to the clinically affected side, and in the bilateral thalamus. DAT availability was reduced bilaterally, most distinctly on the side contralateral to the main motor symptoms.

We replicated and refined earlier findings of impaired glucose metabolism and nigrostriatal degeneration in CBS, highlighting asymmetric cortical and subcortical hypometabolism, symmetrically reduced metabolism in the thalamus, and only a slightly asymmetric reduction in DAT, while D_2/3 receptors seem to be mainly preserved. These results provide systematic evidence for the usefulness of FDG PET and dopaminergic SPECT imaging to characterize CBS.