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 –

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.

Chinese abstract

背景：在由脑半球受损引起的中枢听觉障碍中, 有皮质性耳聋和听觉失灵。尽管已经报道了皮质性耳聋的临床病例, 对于与皮质性耳聋相关的听力问题和局部病变知之甚少。

目的：我们研究的目的是弄清楚与皮层性耳聋相关的病变部位, 并澄清为什么脑损伤患者根本听不到任何声音。

材料和方法：3名被诊断为完全听力丧失的患者参加了这项研究研究。我们进行了纯音测听、语音测听、畸变产物耳声发射（DPOAE）、听觉脑干反应（ABR）和脑磁共振成像（MRI）, 通过这些患者的失语测试来诊断皮质性耳聋。

结果：我们的研究表明, 所有三位患者的ABR的VI和VII波以及I至V波具有正常的峰值潜伏期。在脑部MRI中, 我们发现三名患者的双侧听觉辐射近端部分完全受损。

结论：我们建议将“皮质下耳聋”作为听觉失灵的一种亚型。

Keywords:

• Cortical deafness
• auditory radiation
• MGB
• off-the-scale hearing
• ABR
• MRI
• central auditory processing
• subcortical deafness
• auditory agnosia

Acknowledgements

We thank Dr. Hiroyuki Ito and Dr. Masahiro Rikitake for their clinical contributions and Ms. Kayoko Sekiguchi for her secretarial assistance.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.