Topographic Recording and ERA in the Cases of Intracranial Lesion

The electric response audiometries were performed on 7 cases of unilateral temporal lobe lesion, and 4 cases of brain stem lesion or acoustic tumor.Topographic recordings were applied on one case of severely wounded epidural hematoma. The polarity of slow vertex response was reversed on the unaffected hemisphere, but remained unchanged on the affected hemisphere.ERA by the vertex to the ear lobe recordings revealed that the slow responses showed deep P1 and short N1 latencies by the ipsilateral stimulation. On the other hand, they showed deep P2 and flattened N1 by the contralateral stimulation.Those changes of slow response were observed in the cases of 1, 2 and 3. of 6 cases.