BackgroundCortico-basal degeneration (CBD) is a neurodegenerative disease typically responsible for cortico-basal syndrome (CBS) or progressive limb apraxia. Half of CBD patients, however, present atypical symptoms, making the diagnosis difficult.ObjectiveWe reported the case of a woman in her late sixties (BM208), an unusual case of autopsy-proven CBD, showing early signs of Benson's syndrome or posterior cortical atrophy. In addition, we compared cognitive performance and atrophy in different brain regions of BM208 with other neurodegenerative diseases patients to highlight clinical signs that could have guided the diagnosis earlier.MethodsWe retrospectively compared BM208 to patients with typical amnestic Alzheimer's disease (AD) (n = 18, Mini-Mental State Exam (MMSE) scores between 18 and 24), Benson's syndrome due to AD (n = 3), CBS/progressive supranuclear palsy (PSP) syndrome (n = 5), and Lewy body dementia (LBD) patients (n = 3) and a control group (n = 24). All these participants underwent an MMSE, a complete neuropsychological examination and 3DT1 MRI.ResultsAlthough BM208 was more severely cognitively impaired overall, her cognitive performance was more similar to Benson's syndrome patients' cognitive profile compared to CBS patients or any other degenerative pathology (typical AD/LBD). Consistently, although BM208 was more atrophic than all other groups, she showed cortical atrophy that matched a Benson's syndrome pattern more than typical AD or CBS. However, the analysis of subcortical atrophy revealed atrophy of the basal ganglia corresponding CBS cases. Furthermore, visual analyses on sagittal T1 images showed atrophy of the midbrain, characteristic of CBS/PSP syndrome.ConclusionsThese results highlight the additive value of fine-grained MRI subcortical quantification to diagnose non-AD rare neurodegenerative disorders.