Cortical auditory disorders: clinical and psychoacoustic features.

Abstract

SUMMARYThe symptoms of two patients with bilateral cortical auditory lesions evolved from cortical deafness to other auditory syndromes: generalised auditory agnosia, amusia and/or pure word deafness, and a residual impairment of temporal sequencing. On investigation, both had dysacusis, absent middle latency evoked responses, acoustic errors in sound recognition and matching, inconsistent auditory behaviours, and similarly disturbed psychoacoustic discrimination tasks. These findings indicate that the different clinical syndromes caused by cortical auditory lesions form a spectrum of related auditory processing disorders. Differences between syndromes may depend on the degree of involvement of a primary cortical processing system, the more diffuse accessory system, and possibly the efferent auditory system.Since the original description in the late nineteenth century, a variety of disorders has been reported from bilateral lesions of the auditory cortex and its radiations. The clinical syndrome of cortical deafness in a woman with bitemporal infarction was described by Wernicke and Friedlander in 1883.' The term auditory agnosia was used by Freud in 1891,2 and has been used alternately for two observed syndromes: a selective decrease in recognition of non-verbal sounds and a generalised decrease in recognition of both verbal and non-verbal sounds. Lissauer (1890) proposed the existence of an apperceptive agnosia resulting from inability to synthesise sensory information into an adequate percept.3 Kussmaul (1877) first described a patient with pure word deafness,4 and Bernard (1889) noted an amusia where melodies lose their musical character. I Since that time, many other cases have been reported and attributed to lesions involving the cortical auditory areas.6-10It is still not fully understood how dysfunction of the cortex results in these diverse syndromes and whether they are functionally related or truly distinct.3 Investigators disagree as to whether true deafness can result from cortical lesions.6 1112 Case

Simultaneous auditory agnosia: Systematic description of a new type of auditory segregation deficit following a right hemisphere lesion

“…The patient's descriptions are consistent with immediate auditory deafness, which evolved 479 into auditory agnosia-which is not uncommon (Mendez & Geehan, 1988)-and a 480…”

Auditory Dysfunction in Patients with Cerebrovascular Disease

“…The central auditory nervous system consists of cortical, subcortical, and interhemispheric connections [8]. Differences between syndromes might depend on the degree to which the primary cortical processing, accessory, and efferent auditory systems are involved [9]. …”

Identifying environmental sounds: a multimodal mapping study

“…Auditory agnosia is a rare neuropsychological disorder; the literature about auditory agnosia mainly consists of case studies. The lesions related to this disorder are not particularly consistent as they can involve the temporal or temporo-parietal cortex (Vignolo, 1982 ; Fujii et al, 1990 ; Schnider et al, 1994 ; Engelien et al, 1995 ; Clarke et al, 2000 , 2002 ; Saygin et al, 2003 ), subcortical areas (Kazui et al, 1990 ) such as the thalamus (Clarke et al, 2000 ) as well as the putamen (Taniwaki et al, 2000 ), the right hemisphere (e.g., Vignolo, 1982 ; Fujii et al, 1990 ; Schnider et al, 1994 ; Clarke et al, 1996 ), the left hemisphere (e.g., Vignolo, 1982 ; Schnider et al, 1994 ; Clarke et al, 1996 , 2000 ), and both hemispheres (Rosati et al, 1982 ; Vignolo, 1982 ; Mendez and Geehan, 1988 ; Engelien et al, 1995 ; Clarke et al, 1996 ; Nové-Josserand et al, 1998 ). Left hemisphere (and bilateral) lesions tend to produce additional deficits in verbal comprehension.…”