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[The logopenic variant of primary progressive aphasia].

The logopenic variant of primary progressive aphasia [also referred to as logopenic progressive aphasia (LPA)] is the most recently identified variant of primary progressive aphasia (PPA). This disorder, characterized by a unique speech and language profile, occurs due to damage to specific anatomical areas. An international panel of experts has established a set of diagnostic criteria for PPA and its clinical variants. The clinical diagnostic criteria for the logopenic variant include core features such as impaired single-word retrieval in spontaneous speech and impaired repetition of sentences and phrases. Additional features, of which at least 3 are essential for diagnosing the logopenic variant, include phonological errors in speech, spared single-word comprehension and object knowledge, spared motor speech, and lack of frank agrammatism. For a next imaging-supported diagnosis, the aforementioned clinical features must be accompanied by imaging findings revealing atrophy, hypoperfusion, or hypometabolism in the left temporo-parietal junction area. Finally, a pathology-confirmed case of the logopenic variant requires a clinical diagnosis of the syndrome accompanied by histopathological data or the presence of a known pathogenic mutation. Studies have clarified the clinical phenotype of this disorder, suggesting a prominent impairment of the phonological working memory. Several studies have provided evidences of a possible link between the logopenic phenotype and the specific pathological and genetic correlates. The diagnostic guidelines will enable a more accurate identification of the individuals with the logopenic variant, thus facilitating the documentation of the course of illness and, ultimately, the underlying pathological substrate in this patient group via the pathology-confirmed series.