A comparison of the three-dimensional auditory brainstem response and the conventional auditory brainstem response in...

For measurement of neural activity in the brainstem auditory pathway, the conventional two-dimensional (2D) auditory brainstem response (ABR) does not provide a true response, because the equivalent dipoles originate from the stereoregularity pathway. It is thus necessary to use three-dimensional (3D) ABR to estimate the true response of the brainstem. We recorded 3D ABR in a group of children and adults, and compared the results with those of the conventional 2D ABR. The subjects were 22 children (age range 3-10 years) and 10 adults with no neurological disorders, and three patients: a boy and a girl who had experienced sudden brainstem dysfunction, and a girl who had sudden deafness. 3D ABR was recorded for all subjects, and the results were displayed on a computer screen for off-line analysis using an original 3D ABR analysis program. Four leaf-like vector segments of 3D ABR existed during the first 8 ms after stimulation. Each vector segment corresponded to a peak of the conventional ABR, and showed the original directivity. The amplitudes of waves II and IV of the 3D ABR were significantly larger than those of the conventional ABR. 3D ABR was shown to be superior to the conventional ABR in obtaining absolute amplitude. We were able to clarify the development of brainstem function using 3D ABR. In one patient in whom only one wave was obtained, 3D ABR was able to identify the wave as wave V. These results indicate that ABR is useful both for identifying the kind of wave produced and for suggesting the wave origin.