IC‐P‐007: The overlap between the corticobasal degeneration syndrome and nonfluent aphasia

Recent clinicopathological studies demonstrated an association between the presenting syndrome of nonfluent aphasia and the pathological diagnosis of corticobasal degeneration. In this study, we present clinical, neuropsychological, and structural MRI data of patients with nonfluent aphasia, apraxia of speech, ideomotor limb apraxia and extrapyramidal signs at presentation compared to those of patients with the classic primary progressive aphasia (PPA). Four patients with a CBS-nonfluent aphasia syndrome at presentation and three patients with the nonfluent PPA variant were studied. Structural MRI scans were obtained also from 10 age- and sex-matched healthy controls were studied. Grey matter (GM) atrophy patterns were assessed using voxel-based morphometry. Compared with controls, both CBS-nonfluent and nonfluent PPA patients showed atrophy of the left insula. In addition, CBS-nonfluent patients had GM atrophy involving the left rolandic operculum, precentral and postcentral gyri, superior temporal gyrus, middle cingulum, and inferior parietal lobule, while patients with nonfluent PPA experienced atrophy of the left superior frontal gyrus, inferior temporal gyrus, anterior/middle cingulum, and bilateral amygdala. The direct comparison between the two patient groups showed that CBS-nonfluent patients had a greater atrophy of the left rolandic operculum, postcentral gyrus, and inferior parietal lobule compared with nonfluent PPA. On the contrary, patients with nonfluent PPA had a greater tissue loss of the left superior frontal gyrus, inferior temporal gyrus, and bilateral amygdala compared with those with the CBS-nonfluent variant. Our findings corroborate the overlap between nonfluent PPA and CBS. This study also suggests that specific anatomical substrates are associated with different clinical symptoms in these patients. The damage to the left insula in all patients highlights its role in motor speech deficits, while the parietal damage is likely to be related to limb apraxia.