Chronic auditory agnosia following Landau-Kleffner syndrome: a 23 year outcome study
We report a 27-year-old woman with chronic auditory agnosia following Landau-Kleffner Syndrome (LKS) diagnosed at age 4 1/2. She grew up in the hearing/speaking community with some exposure to manually coded English and American Sign Language (ASL). Manually coded (signed) English is her preferred mode of communication. Comprehension and production of spoken language remain severely compromised. Disruptions in auditory processing can be observed in tests of pitch and duration, suggesting that her disorder is not specific to language. Linguistic analysis of signed, spoken, and written English indicates her language system is intact but compromised because of impoverished input during the critical period for acquisition of spoken phonology. Specifically, although her sign language phonology is intact, spoken language phonology is markedly impaired. We argue that deprivation of auditory input during a period critical for the development of a phonological grammar and auditory-verbal short-term memory has limited her lexical and syntactic development in specific ways.