Clinical Profile of PiB-Positive Corticobasal Syndrome

Background: Corticobasal syndrome (CBS) is a multifaceted neurodegenerative disorder characterized by a combination of motor and cognitive deficits. Several different pathological entities, including Alzheimer's pathology, have been described in association with CBS. The present study aimed to establish clinical, neuropsychological, and neuroimaging features that could be useful in the distinction of CBS due to AD pathology from other CBS cases in life based on [C-11] Pittsburgh Compound B positron emission tomography (PiB-PET) status. Methods: Patients with CBS were prospectively recruited from a specialized cognitive disorders clinic. All patients underwent detailed clinical and neuropsychological assessment, with structural imaging using voxel-based analysis of magnetic resonance imaging. Alzheimer's pathology was detected using PiB-PET imaging, and PiB-positive and PiB-negative groups were compared. Results: Fourteen CBS patients meeting defined criteria were included (7 male, 7 female; mean age 66.1+/-6.9 years; median symptom duration was 35.5+/-22.6 months) and compared to 20 matched control subjects. Of the 14 patients, 4 were PiB-positive and 10 PiB-negative. There were no significant differences between PiB-positive and PiB-negative CBS patients in age, gender, education, symptom duration, or motor features. PiB-positive patients had greater visuospatial deficits, a higher rate of sentence repetition impairment, and more functional decline. Voxel-based morphometry analyses demonstrated extensive peri-insular and post-central atrophy in both groups, but PiB-positive patients had atrophy that extended to include the posterior part of the left superior temporal gyrus. Conclusions: Visuospatial function, aspects of language, and the pattern of cerebral atrophy may be useful in distinguishing patients with CBS due to underlying AD pathology.