A posterior variant of corticobasal syndrome: Evidence from a longitudinal study of cognitive and functional status in a single case

Abstract

We describe a patient (CG) suffering from early onset dementia who presented with corticobasal syndrome (CBS). The aims of the study were as follows: (i) a detailed description of the cognitive phenotype; (ii) a comprehensive, longitudinal evaluation of apraxia; (iii) an appraisal of the impact of apraxia and other cognitive impairments on patient functional status; and (iv) an indirect mapping of degeneration spreading. A three-year longitudinal, observational follow-up study of cognitive and functional status was performed. Four main results emerged. First, an unusual CBS phenotype appeared that was characterized by symmetrical presentation, asymmetrical course, and prominent posterior (bi-parietal) cognitive and motor cortical manifestations. Second, some findings of limb apraxia in CBS were replicated and substantiated; moreover, some novel findings of other cognitive impairments emerged. Third, an early, significant functional decline, probably related to apraxia and to visuospatial attention impairments, became apparent. Fourth, CG’s clinical picture was compatible with an underlying dysfunction of the large-scale, dorsal sensory-motor association network, as already suggested in previous CBS cases. This case report confirms the heterogeneity of CBS and suggests the emergence of a possible less common variant, i.e. the posterior CBS (P-CBS).

• Keywords
• corticobasal
• limb-apraxia
• limb-kinetic
• alien hand syndrome
• brain network

Public Interest Statement

Our research group studies the dramatic mind’s decline resulting from the progressive brain damage caused by Alzheimer’s disease and other dementias. Specifically, we aim to precisely report all the impairments that dementia causes in mental abilities as well as in feelings and behavior of the patients, and how these disorders change over time. This scientific knowledge may help detect the early features of dementia to diagnose it as soon as possible. Moreover, we are interested in forecast what difficulties patients will have in their daily lives, as well as how they will behave in some circumstances and what emotions they will feel. The ultimate aim of this long-lasting and demanding study is to know better how to help patients and make them feel well. Also, we want to make patients’ mind stronger and to promote social engagement for them.

Competing interests

The authors declare no competing interest.

Acknowledgments

Special thanks are due both to patient CG and her daughter for their longstanding cooperation with interviews, examinations and testing. Moreover, many thanks are due to Luigi Ghilardini for editing digital Figures 1 and 2 and to Silvia Casarotto for her help in editing Figure 3.

Additional information

Notes on contributors

Carlo Abbate

Carlo Abbate and Pietro Davide Trimarchi are neuropsychologists and clinical researchers, who specialize in dementia diagnosis. Carlo Abbate has a PhD in Physiopathology of Aging at the University of Milan and works at the Fondazione Ca’ Granda, Ospedale Maggiore Policlinico in Milan. Pietro Davide Trimarchi has a PhD in Experimental Psychology and Cognitive Neuroscience at the University of Milano–Bicocca and works at Fondazione Don Carlo Gnocchi, in Milan. They have been working together for years in many research areas: early cognitive markers of dementia, Mild Cognitive Impairment, clinical syndromes of dementia, qualitative neuropsychological examination, and variants of Alzheimer’s disease. The firm belief that neuropsychology can be a helpful tool both to understand and to diagnose dementia has guided their work. The detailed longitudinal study of the cognitive and behavioral status of a young adult patient with degenerative dementia presented here well exemplifies the method adopted by the authors.