Subcortical deafness as a subtype of auditory agnosia after injury of bilateral auditory radiations caused by two cerebrovascular accidents - normal auditory brainstem responses with I-VII waves and abolished consciousness of hearing.

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.