1987 Volume 30 Issue 6 Pages 804-811
Sequential recording of the auditory brain stem response (ABR), middle latency response (MLR) and slow vertex response (SVR) under logarithmic time scale were applied for the 17 cases of central lesions, in order to obtain more informations as for the localization of the lesions.
The recording is vertex-ipsilateral mastoid to the acoustic stimuli, click with 80dB nHL or 100dB nHL.
The averaging numbers are 500 times and analysis time is 500msec. Pass-band of the filter is 2-2000Hz and sampling clock is 100usec on A-D conversion. The results were as follows;
The modality of MLR and SVR showed remarkable changes by the site of the lesions.
1) Temporal lobe lesions gave influence upon ABR and MLR very few, however, the N-P2 component of SVR was greatly affected.
2) Subcortical lesions showed little variation upon ABR, however, latency-prolongation of each component of MLR and SVR or dicrease of their amplitude were clearly identified.
3) Some of the upper brain stem lesions showed almost normal SVR.
4) As for the lower brain stem lesions or C-P angle lesions, MLR and SVR provided poor information.
5) Degenerative disorders of the brain (ex. multiple sclerosis) could fairly be diagnosed by comparing the sequential changes of ABR and MLR with normal SVR.
Logarithmic time-scale recording can identify the sequential modality of AEP, and pathological influence upon the auditory pathway by some central lesions could lead us to speculate the site of the lesions.