2023 Volume 43 Issue 2 Pages 161-165
Primary progressive aphasia (PPA) is classified according to current diagnostic criteria as nonfluent/agrammatic variant PPA (nfvPPA) , semantic variant PPA (svPPA) , or logopenic variant PPA (lvPPA) . However, some previous cases of PPA did not fulfil any of these criteria. One of the syndromes observed in the cases was progressive word deafness (or progressive auditory agnosia) . The damage in the auditory cortex and/or the acoustic radiation, which are the key parts of the auditory central nervous system, can cause auditory agnosia. Word deafness can be caused when there is damage to the language-dominant hemisphere. Patients with word deafness usually have preserved pure-tone thresholds, whereas their phonological perception of speech sounds is impaired. Because PPA is a syndrome caused by underlying neurodegenerative diseases, the impairment of auditory central nervous system progresses and induces specific auditory symptoms depending on underlying disease. The major auditory processing deficits and auditory symptoms are different among nfvPPA, svPPA, and lvPPA. We summarized the latest findings regarding progressive word deafness. In addition, we mentioned the importance of evaluating speech sound perception, which is fundamental for detecting word deafness in PPA. It is very difficult to accurately evaluate speech sound perception because it can be influenced by language function. As an example of assessment methods, we presented a case in which we attempted to assess basic auditory function and auditory language comprehension using various auditory and linguistic tasks.
