Pathology-Proven Corticobasal Degeneration Presenting as Richardson's Syndrome

Background: Corticobasal degeneration (CBD) can present with various clinical phenotypes including Richardson's syndrome (RS). Although neuropathological examination can differentiate CBD and progressive supranuclear palsy (PSP) pathologies, no clinical or imaging findings can differentiate CBD from other pathologies when a patient presents with a variant type of CBD. As these various phenotypes are associated with non-CBD pathologies, clinical diagnostic accuracy can be low for such patients. Objectives: To present clinical features of two cases with symptom progression in line with PSP-RS, who were diagnosed with CBD based on neuropathological examination. Methods: Baseline, follow up examinations, and detailed neuropathological examinations of two CBD cases presenting and progressing in line with probable PSP-RS are demonstrated. Results: The two cases clinically diagnosed as probable PSP-RS were shown to have CBD upon neuropathological examination, which is the gold standard for diagnosis of both PSP and CBD. Conclusions: These cases emphasize the importance of neuropathology for the definite diagnosis, and stress the need for distinctive markers to increase the reliability of clinical diagnosis before death.