Unclassified fluent variants of primary progressive aphasia: distinction from semantic and logopenic variants

Abstract

Primary progressive aphasia, a neurodegenerative syndrome, presents mainly with language impairment. Both semantic and logopenic variants are fluent variants of primary progressive aphasia. Before the research criteria of primary progressive aphasia were proposed, progressive fluent aphasias, such as progressive anomic aphasia, transcortical sensory aphasia, and Wernicke’s aphasia, were reported as classical progressive fluent aphasias seen in Alzheimer’s disease. However, since the research criteria of primary progressive aphasia were established, classical fluent variants (other than semantic and logopenic variants) have been neglected and have not been included in the current classification of primary progressive aphasia. This study aimed to determine whether unclassified fluent variants (other than semantic and logopenic variants) can be manifestations of primary progressive aphasia. This study also reconfirmed the characteristics of classical progressive fluent aphasia, such as progressive anomic aphasia, progressive transcortical sensory aphasia, and progressive Wernicke’s aphasia as unclassified fluent variants of primary progressive aphasia, using comparison with the current model of primary progressive aphasia. Twelve consecutive patients with an unclassified fluent variant other than semantic or logopenic variant underwent language, neurological, neuropsychological, and neuroimaging (MRI and single-photon emission computed tomography) testing. Based on comprehensive language tests, we redefined the diagnoses as primary progressive anomic aphasia (n = 8), primary progressive transcortical sensory aphasia (n = 3), and primary progressive Wernicke’s aphasia (n = 1). Anomic aphasia was characterised by anomia but preserved repetition and comprehension; transcortical sensory aphasia by relatively preserved repetition but poor word comprehension; and Wernicke’s aphasia by poor repetition and word comprehension. In patients with anomic aphasia, voxel-based morphometry of MRI data revealed cortical atrophy, which was most prominent in the temporoparietal lobes, with no obvious lateralisation; in 2/3 of patients with transcortical sensory aphasia and in one patient with Wernicke’s aphasia, it revealed atrophy, predominantly in the left temporoparietal lobe. Statistical analysis of single-photon emission computed tomography using three-dimensional stereotactic surface projections revealed patterns of left-sided hypoperfusion in the majority of patients. The temporal and parietal lobes were involved in all cases; the degree of hypoperfusion was higher in patients with transcortical sensory aphasia or Wernicke’s aphasia than in patients with anomic aphasia. The present study demonstrated the clinical and imaging features of 12 patients with an unclassified fluent variant of primary progressive aphasia, which we redefined as primary progressive anomic aphasia, primary progressive transcortical sensory aphasia, and primary progressive Wernicke’s aphasia. Classical fluent variants other than semantic and logopenic variants can be found in primary progressive aphasia.

Silent Pauses and Speech Indices as Biomarkers for Primary Progressive Aphasia

“…However, this is not always applicable, as patients do not always visit a clinician early enough for the initial manifestations of the disease to be directly assessed. More recent evidence highlights the problem of unclassified patients (see for example: [ 4 , 19 , 20 , 21 , 22 , 23 , 24 ]), indicating that these patients may present left-lateralized yet less extensive atrophy in language-related areas [ 19 , 20 ], as well as language deficits in more than one domain [ 20 ]. Moreover, Mesulam and colleagues [ 4 ] proposed that the same pathology may induce more than one variant and that the same PPA variant can be caused by more than one neuropathological entity, while in other studies it has been stated that dual pathologies may exist within the same patient [ 21 ].…”

“…Moreover, Mesulam and colleagues [ 4 ] proposed that the same pathology may induce more than one variant and that the same PPA variant can be caused by more than one neuropathological entity, while in other studies it has been stated that dual pathologies may exist within the same patient [ 21 ]. It should be noted that additional categories, such as primary progressive anomic aphasia, primary progressive transcortical sensory aphasia, and primary progressive Wernicke’s aphasia, have also been proposed [ 22 ], suggesting that the PPA taxonomy should be reconsidered [ 19 , 20 , 23 , 24 ]. The taxonomy issue is highly related to the time of diagnosis.…”

Dyslexia and dysgraphia of primary progressive aphasia in Chinese: A systematic review

“…Sixteen patients (five with nfvPPA, four with svPPA, and seven with lvPPA) with detailed clinical manifestations lacked respective demographic data and thus were not included here. In addition, three cases were classified as unclassified PPA ( 21 , 22 ). A total of 161 patients were therefore included in Table 1 .…”

Aphasic mild cognitive impairment in prodromal dementia with Lewy bodies

“…Their language features were characterized by apparent anomia, and their repetition and comprehension abilities were relatively preserved. Therefore, based on the current research findings for unclassified fluent variants of PPA (6,42,43), five patients (cases 1-5) were diagnosed with progressive anomic aphasia. At visit 2, three patients (cases 2, 4, and 8) underwent followup examinations after 1 year (Table 2).…”