Progressive Aphasia, Apraxia of Speech and Agraphia in Corticobasal Degeneration: A 12-Case Series Clinical and Neuropsychological Descriptive Study

Background: Despite initial underreporting of language dysfunctions in corticobasal syndrome (CBS), aphasia is now recognized as a frequent feature of this disease. Aphasia in CBS seems clinically overlying to a non-fluent/agrammatic primary progressive aphasia (nfaPPA), which is also a clinical phenotype associated with corticobasal degeneration (CBD) pathology. However, the clinical features of aphasia in CBS still remain poorly delineated, resulting in misjudgements in the differential diagnosis from a PPA presentation of the disease. Aims: To investigate the language disorders of this syndrome, also through a systematic examination of recoding skills (reading, written spelling and repetition) and articulatory disturbances, which have been rarely examined in previous studies. Methods & Procedures: We present a clinical and neuropsychological descriptive study of the language impairments in a case series of 12 aphasic patients with a clinical diagnosis of CBS. Language assessment was conducted by means of the Esame NeuroPsicologico dell'Afasia, a comprehensive Italian battery for language functions, the Token Test, and the Apraxia of Speech Rating Scale. Outcomes & Results: The language profile of the patients showed a severe expressive language disorder, characterized by non-fluent speech, apraxia of speech (AoS) with predominant stuttering-like dysfluencies, spatial/apraxic agraphia, lack of word-finding and defective sentence repetition. Severe limb apraxia, visual-spatial deficit and alien hand syndrome were also present. Neuroimaging showed bilateral left asymmetric atrophies and hypometabolism in the frontal premotor, parietal posterior and temporal areas. Conclusions & Implications: These findings suggest that aphasia in CBS might present as a 'mixed PPA', instead of an nfaPPA as previously stated, showing a combination of features of the nfa and logopenic variants of the PPA, associated with AoS, stuttering and agraphia, which might be additional important cognitive markers for the clinical diagnosis of CBS and discriminating features of an nfaPPA presentation of a CBD. These results might also suggest specific intervention areas in the rehabilitation of patients with CBS.