Cortical Deafness: A Case of Selective Auditory Agnosia, Amusia and Word Deafness (P07.177)

Abstract

Objective: To understand the neurological basis in the cortical appraisal of auditory stimuli. Background This paper presents a sixty-four year old ex-soldier with word deafness, auditory agnosia for environmental sounds and selective amusia. Studies demonstrate perceptual channels for amplitude-modulated frequencies in the auditory cortex. Design/Methods: The imaging demonstrated a left-sided middle cerebral artery infarct affecting predominantly the temporal lobes on top of a three year old right-sided temporal infarct. A functional MRI tractography was performed. The acoustic immittance testing and auditory evoked brainstem responses were normal in both ears. Acoustic reflex decay was not attempted, because acoustic reflexes were elevated. Consistent with occupation, audiometry found bilateral moderate-severe sensorineural hearing loss for high frequencies. Twenty environmental and music sound tracks were presented followed with a brief questionnaire after each track. Five subjects (M(age)=64) with normal hearing were also asked to complete the same task. Results: The patient was impaired for the environmental sounds (t=9.654, p= Conclusions: Collectively, the deficit pattern represents a selective agnosia and low frequency deafness. The sensorineural hearing loss describes the incomplete comprehension of high frequency environmental sounds. Frequency appraisals of auditory stimuli occur peripherally and centrally with hierarchical organization of auditory stimuli, cortically. Verbal and non-verbal stimuli are initially processed by the cortex, filtering a complex pattern of frequencies. Characterizing deafness as being verbal or non-verbal is inadequate. Thus, areas in the cortex must attribute quantitative, and not only the qualitative properties of auditory stimuli. Disclosure: Dr. Hasan has nothing to disclose. Dr. Mohammed has nothing to disclose. Dr. Hodgson has nothing to disclose. Dr. Silva has nothing to disclose.