Objective: This study aims to describe the patterns of white-matter damage using diffusion tensor imaging (DTI) in individuals with Corticobasal Syndrome (CBS) and compare the patterns among CBS associated with Alzheimer’s disease (AD) from those related to other etiologies.

Background: CBS is an atypical parkinsonian disorder characterized by asymmetric parkinsonism, apraxia, and a mix of cortical sensory, motor, and cognitive deficits. While it is traditionally associated with corticobasal degeneration, it can also originate from other neuropathologies, such as progressive supranuclear palsy and AD. Clinical symptoms alone are unable to predict underlying pathology. However, previous studies have shown that the degeneration patterns of white matter tracts may aid in distinguishing between different etiologies.

Method: We enrolled 31 patients diagnosed with CBS and matched them with healthy controls. All participants underwent MRI-based DTI and also performed  [11C]Pittsburgh Compound-B (PIB)-PET imaging on a hybrid 3T PET-MRI to assess their brain amyloid deposition. Patients were categorized based on their amyloid status: CBS associated with AD (CBS-AD, n = 13) or CBS not associated with AD (CBS non-AD, n = 18). White matter abnormalities evaluated through DTI on fractional anisotropy (FA) and mean diffusivity (MD) images were quantified using the MRICloud platform, and statistical analyses were corrected for multiple comparisons using the Bonferroni method.

Results: The CBS AD and non-AD groups were comparable in terms of age (mean age CBS-AD = 68 years and CBS non-AD = 65 years) and disease duration (with an average disease duration of 4 years). Significant white matter damage was observed in both groups in the corpus callosum, fornix, tapetum, reticular formation, sagittal stratum, and the left posterior thalamic radiation. Additionally, the CBS non-AD group presented further microstructural white matter alterations in the fornix stria terminalis, superior cerebellar peduncle, inferior fronto-occipital fasciculus, and cerebral peduncle.

Conclusion: DTI shows both overlapping and distinct pathology-related patterns of white matter degeneration in CBS. The observation of additional regional involvement in CBS non-AD highlights the potential of DTI as a diagnostic biomarker for identifying underlying neuropathological substrates in vivo.

References: 1.Parmera JB, Oliveira MCB, Rodrigues RD, et al. Progressive supranuclear palsy and corticobasal degeneration: novel clinical concepts and advances in biomarkers. Arq Neuropsiquiatr. 2022 May;80(5 Suppl 1):126-136
2.McMillan CT, Boyd C, Gross RG, et al. Multimodal imaging evidence of pathology-mediated disease distribution in corticobasal syndrome. Neurology. 2016 Sep 20;87(12):1227-34
3.Whitwell JL, Schwarz CG, Reid RI, et al. Diffusion tensor imaging comparison of progressive supranuclear palsy and corticobasal syndromes. Parkinsonism Relat Disord. 2014 May;20(5):493-8

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MDS Abstracts - https://www.mdsabstracts.org/abstract/differentiating-white-matter-damage-patterns-by-underlying-pathology-in-corticobasal-syndrome/