The purpose of this study was to measure, in the cat, spontaneous auditory nerve (AN) activity before and after injection with sodium salicylate. Ten cats were anesthetized, and the AN and round window (RW) were surgically exposed. Electrodes were applied to allow recording from three channels, including bipolar electrodes and monopolar electrodes located directly on the auditory nerve, in addition to an RW electrode. Spectral averaging of the spontaneous activity was performed before and during salicylate treatment. An increase in spectral activity near 200 Hz was noted in all cats by 3 hours after salicylate injection. This activity was present in bipolar, monopolar, and RW records, and was temporarily diminished or eliminated by injection of lidocaine. No such spectral changes were found in saline-injected control animals. These results show promise of developing a noninvasive, objective, quantitative measure of tinnitus for studies in animals and in man.
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