Prediction of pathology in primary progressive language and speech disorders

Frontotemporal lobar degeneration (FTLD) encompasses a variety of clinicopathologic entities. The antemortem prediction of the underlying pathologic lesions is reputed to be difficult. This study sought to characterize correlations between 1) the different clinical variants of primary progressive language and speech disorders and 2) the pathologic diagnosis.

The latter was available for 18 patients having been prospectively monitored in the Lille Memory Clinic (France) between 1993 and 2008.

The patients were diagnosed with progressive anarthria (n = 5), agrammatic progressive aphasia (n = 6), logopenic progressive aphasia (n = 1), progressive jargon aphasia (n = 2), typical semantic dementia (n = 2), and atypical semantic dementia (n = 2). All patients with progressive anarthria had a tau pathology at postmortem evaluation: progressive supranuclear palsy (n = 2), Pick disease (n = 2), and corticobasal degeneration (n = 1). All patients with agrammatic primary progressive aphasia had TDP-43-positive FTLD (FTLD-TDP). The patients with logopenic progressive aphasia and progressive jargon aphasia had Alzheimer disease. Both cases of typical semantic dementia had FTLD-TDP. The patients with atypical semantic dementia had tau pathologies: argyrophilic grain disease and corticobasal degeneration.

The different anatomic distribution of the pathologic lesions could explain these results: opercular and subcortical regions in tau pathologies with progressive anarthria, the left frontotemporal cortex in TDP-43-positive frontotemporal lobar degeneration (FTLD-TDP) with agrammatic progressive aphasia, the bilateral lateral and anterior temporal cortex in FTLD-TDP or argyrophilic grain disease with semantic dementia, and the left parietotemporal cortex in Alzheimer disease with logopenic progressive aphasia or jargon aphasia. These correlations have to be confirmed in larger series.