Brain lesion diagnosis by recording cochlear and brainstem responses to sound stimuli

A technique has been developed for the recording of the cochlear action potential (electrocochleography) and the brainstem evoked responses to click stimuli by means of earlobe and scalp electrodes with an average response computer. This technique has already proved its usefulness in diagnosis of hearing loss. Since the brainstem responses are generated in the successive brainstem auditory nuclei and since the auditory nuclei and pathways constitute a relatively large volume of brainstem tissue, there is reason to believe that this same technique can also contribute to the diagnosis of brainstem lesions and their localization. When these recordings were made in patients with clinical signs of brainstem involvement, one (or more) of the usual response waves was smaller in amplitude, prolonged in latency, or completely absent. Recording of the cochlear and brainstem evoked potentials thus seems to be a new, simple and rapid tool for the diagnosis of brainstem lesions.