Preservation of waves VI and VII of ABR in pediatric and adult patients with lesions in bilateral auditory cortices or radiations.

Background: Auditory-evoked brainstem response (ABR) is widely used in various areas of clinical medicine. There is a common understanding regarding the origins of waves I to V in human ABR. However, little is known from where wave VI or VII originates in the central auditory pathway.

Aims/objectives: The aim of our research is to elucidate the origins of waves VI and VII by studying ABR amplitude and latency and conducting magnetic resonance imaging (MRI).

Materials and methods: Eleven patients diagnosed as having central auditory disorders participated in this study. They include five pediatric patients with herpes simplex infection and six adult patients with cerebrovascular events manifesting auditory agnosia or cortical deafness with lesions in the bilateral auditory cortices.

Results: We found that waves VI and VII formed into one complex wave with biphasic peaks and the origin of these waves can be the medial geniculate body (MGB).

Conclusions: On the basis of anatomical and electrophysiological findings, we suggest that the latency of VI-I or VII-I nerve conduction time is the auditory brainstem-thalamus transmission time.