Ryohei Akiyoshi1,2, Mitsuko Shindo1,3, Kimitaka Kaga1,4. 1. National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan. 2. Department of Otorhinolaryngology, Dokkyo Medical University Saitama Medical Center, Saitama, Japan. 3. Speech-Language-Hearing Therapist Department of Social Welfare, Faculty of Humanities and Social Sciences, Showa Women's University, Tokyo, Japan. 4. Department of Otolaryngology, Kamio Memorial Hospital, Tokyo, Japan.
Abstract
BACKGROUND: In central auditory disorders caused by damage of the cerebral hemispheres, there are cortical deafness and auditory agnosia. Although clinical cases of cortical deafness have been reported, little is known about the hearing problems and localized lesions associated with cortical deafness. AIMS/ OBJECTIVES: The aims of our research are to elucidate lesion sites associated with cortical deafness and to clarify why patients with cerebral lesions are not aware of any sound at all. MATERIALS AND METHODS: Three patients diagnosed as having total loss of hearing participated in this study. We conducted pure-tone audiometry, speech audiometry, distortion product otoacoustic emission (DPOAE), auditory brainstem response (ABR), and brain magnetic resonance imaging (MRI) to diagnose cortical deafness with aphasia tests of these patients. RESULTS: Our studies showed that waves VI and VII as well as waves I to V have normal peak latencies in ABRs in all three patients. In brain MRI, we found complete damage of proximal parts of bilateral auditory radiations in the three patients. CONCLUSIONS: We propose 'subcortical deafness' as a subtype of auditory agnosia.
BACKGROUND: In central auditory disorders caused by damage of the cerebral hemispheres, there are cortical deafness and auditory agnosia. Although clinical cases of cortical deafness have been reported, little is known about the hearing problems and localized lesions associated with cortical deafness. AIMS/ OBJECTIVES: The aims of our research are to elucidate lesion sites associated with cortical deafness and to clarify why patients with cerebral lesions are not aware of any sound at all. MATERIALS AND METHODS: Three patients diagnosed as having total loss of hearing participated in this study. We conducted pure-tone audiometry, speech audiometry, distortion product otoacoustic emission (DPOAE), auditory brainstem response (ABR), and brain magnetic resonance imaging (MRI) to diagnose cortical deafness with aphasia tests of these patients. RESULTS: Our studies showed that waves VI and VII as well as waves I to V have normal peak latencies in ABRs in all three patients. In brain MRI, we found complete damage of proximal parts of bilateral auditory radiations in the three patients. CONCLUSIONS: We propose 'subcortical deafness' as a subtype of auditory agnosia.