Progressive transcortical sensory aphasia and progressive ideational apraxia owing to temporoparietal cortical atrophy

In contrast to frontotemporal lobar degeneration, atrophy of the focal posterior lateral cortex has not been thoroughly studied. Three clinical types of focal cortical atrophy have been described: 1) logopenic variant of primary progressive aphasia, which presents with impaired repetition despite normal articulation; 2) posterior cortical atrophy, which presents with prominent visuospatial deficits; and 3) primary progressive apraxia. All three clinical types are characterized by specific patterns of hypometabolism/hypoperfusion: the left posterior perisylvian area in the logopenic variant of primary progressive aphasia, bilateral parietooccipital areas in posterior cortical atrophy, and the parietal cortex in primary progressive apraxia. However, not every patient clearly fits into one of these categories.

Here we describe two patients with atypical focal cortical presentations. They presented with a history of a few years of progressive transcortical sensory aphasia characterized by fluent output with normal grammar and syntax, normal repetition, sentence comprehension deficits, and anomia without loss of word meaning. They also presented with progressive apraxia that began at the initial stages. Some forms of posterior symptoms including acalculia, agraphia, and visuospatial deficits were also observed. Hypoperfusion was noted mainly in the left temporoparietal region, which is slightly posterior to the perisylvian area.

Although our cases lack in CSF findings and PIB scan, these two cases and previous reports might suggest the existence of a subgroup of patients presenting with transcortical sensory aphasia, apraxia, and posterior symptoms (acalculia, agraphia, and visuospatial deficits) in the setting of Alzheimer's disease. This subgroup may reflect the spectrum of clinical manifestations between logopenic variant of primary progressive aphasia and posterior cortical atrophy.