Word deafness as a cortical auditory processing deficit: A case report with MEG

Abstract

Pure word deafness is a rare disorder dramatically impairing comprehension of spoken language, while auditory functions remain relatively intact. We present a 71-year-old woman with a slowly progressive disturbance of speech perception due to pure word deafness. MRI revealed degeneration of the temporal lobes. A magnetoencephalographic investigation using alternating single tone stimulation showed that N100 was followed by a second transient response and was abnormally prolonged up to 600-700 ms. We conclude that auditory processing is disturbed at long latency ranges following the N100, which may result in the clinical presentation of pure word deafness.

Non-verbal sound processing in the primary progressive aphasias

“…Clinically, patients with PNFA often report altered perception of sound, and non-verbal perceptual and expressive deficits sometimes dominate the clinical presentation (Confavreux et al , 1992; Otsuki et al , 1998; Uttner et al , 2006; Iizuka et al , 2007; Jörgens et al , 2008). Failure to correctly identify and respond to environmental noises not uncommonly accompanies semantic dementia, and a deficit in recognition of meaningful environmental sounds has been documented (Bozeat et al , 2000).…”

Auditory agnosia

“…32.4), including most (5 out of 6) cases that have evaluated click fusion and gap detection thresholds (Fig. 32.4C; Albert and Bear, 1974;Tanaka et al, 1987;Otsuki et al, 1998;Yaqub et al, 1988;J€ orgens et al, 2008; but see Stefanatos et al, 2005b) as well as 3 cases with impaired discrimination of non-speech sine-wave stimuli differing in rapid temporal transitions (Fig. 32.4B; Wang et al, 2000;Stefanatos et al, 2005b;Slevc et al, 2011).…”

“…Patients with verbal auditory agnosia are aware of speech but describe it as sounding like a foreign language (Albert and Bear, 1974), as distorted and cartoonlike (Wee and Menard, 1999), as rapidly fading (Klein and Harper, 1956), or with descriptions like "voice comes but no words" (Hemphill and Stengel, 1940). Speech production in verbal auditory agnosia is relatively normal (Table 32.1), although in some cases production is overly loud and has abnormal prosody (e.g., Otsuki et al, 1998;J€ orgens et al, 2008). Speech perception is typically improved by relying on cross-modal information such as lip reading and from "top-down" contextual information (e.g., Saffran et al, 1976;Coslett et al, 1984;Buchtel and Stewart, 1989;Slevc et al, 2011;Robson et al, 2012).…”

“…Indeed, verbal auditory agnosia typically results from bilateral temporal lesions in the superior temporal cortex (or subcortically, affecting the relevant projecting auditory radiations; see Chapter 1, Fig. 1.9): of 63 reports with sufficiently detailed lesion data (Wang et al, 2000;J€ orgens et al, 2008;Slevc et al, 2011; and earlier cases reviewed by Poeppel, 2001), 43, or almost 70%, involve bilateral lesions. Patients with verbal auditory agnosia are aware of speech but describe it as sounding like a foreign language (Albert and Bear, 1974), as distorted and cartoonlike (Wee and Menard, 1999), as rapidly fading (Klein and Harper, 1956), or with descriptions like "voice comes but no words" (Hemphill and Stengel, 1940).…”

“…While these findings have been taken as evidence that speech perception deficits in verbal auditory agnosia often do result from an underlying deficit in rapid temporal processing (e.g., Phillips and Farmer, 1990; cf. work on developmental language deficits, e.g., Merzenich et al, 1993;Tallal, 2004), it is important to note that not all cases of verbal auditory agnosia are associated with impairments in basic temporal acuity (e.g., Stefanatos et al, 2005b), and some show deficits even with relatively slow temporal changes on the order of hundreds of milliseconds (e.g., Wang et al, 2000;J€ orgens et al, 2008). Furthermore, an attempt to improve rapid temporal processing via a training paradigm in one verbal auditory agnosia patient led to improvements only on discrimination of non-speech stimuli (Slevc et al, 2011), supporting claims that the demands speech perception places on rapid temporal processing are somewhat overstated (McGettigan and Scott, 2012).…”