12 Profound semantic impairment in corticobasal degeneration: A new phenotipic variant of tauopathies

Abstract

Background and purpose It is generally assumed that semantic knowledge is relatively preserved in CBD; however, only few cross-sectional studies have deeply investigated this cognitive domain. Case report Mrs MG, a right-handed 69-year-old woman with 5 years of education, came to our attention in May 2009 complaining a 3-year history of involuntary movements of her left upper limb, associated with clumsiness and pain, and difficult walking. These symptoms had a subtle onset and a progressive course. The neurological examination revealed a left akinetic-rigid extrapyramidal syndrome and dystonia of left upper limb. Her spontaneous speech was fluent, well articulated, grammatically correct and without phonological errors, but flawed by frequent word-finding pauses; verbal comprehension was good. Background neuropsychological evaluation revealed ideomotor apraxia of MG’s left upper limb, associated with dysexecutive syndrome and anomias with sporadic semantic paraphasias in screening naming tests. This unusual feature drew our attention toward a deeper exploration of language, in particular semantics, which confirmed moderate naming impairment with semantic paraphasias, errors in semantic matching tests (PPTT test), difficulty in single word comprehension with tendency to choice semantic distractors. Brain MRI scan showed an asymmetrical atrophy of the right parietal lobe and bilateral atrophy of the temporal pole lobes, more marked on the left side. The SPECT study revealed asymmetrical hypoperfusion in the same areas. The 123-I-FP-DAT SCAN was abnormal. Conclusions The present case provides evidence that semantic knowledge can be damaged in CBD and reinforces the view that tauopathies do have a high phenotypic variability.