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. What this paper addsWhat this paper adds to existing knowledgeWhat is already known on the subjectWhat are the potential or actual clinical implications of this work? Language disorders in CBS patients usually present clinically overlying to an nfaPPA, which is also a clinical phenotype associated with CBD pathology, according to recent diagnostic criteria. However, the clinical features of aphasia in CBS still remain poorly delineated, and this raises difficulties and misjudgements for clinicians in the differential diagnosis from a PPA presentation of the disease. This study shows that the language profile of our CBS patients was characterized by severe expressive language disorders, with non-fluent speech, apraxia of speech (AoS) with predominant stuttering-like dysfluencies, spatial/apraxic agraphia, lack of word-finding, and defective sentence repetition. These findings suggest that aphasia in CBS might present as a 'mixed PPA', rather than 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. These results suggest that AoS, stuttering and agraphia might be important additional cognitive markers for the clinical diagnosis of CBS, and discriminating features of an nfaPPA presentation of a CBD. The language disorders exhibited in the present study might also support speech and language therapists in targeting specific intervention areas in the rehabilitation of patients with CBS.