Multichannel cochlear nucleus stimulation

Stimulation of the cochlear nucleus (CN) has been used on a limited basis f or rehabilitation of a select group of patients with bilateral acoustic neu romas, These patients were implanted with an electrode placed on the surfac e of the CN after resection of their tumors. Animal studies have demonstrat ed greater efficiency of a penetrating CN electrode in activating the centr al auditory system than a surface electrode. The objective of this work was to study the electrically evoked middle latency response generated by stim ulation through a penetrating multichannel CN electrode in an animal model. Six pigmented guinea pigs underwent implantation with a penetrating multic hannel CN electrode. Threshold, latency, and input-output functions of elec trically evoked middle latency responses with different stimulation pads we re studied. There were systematic differences in the latency and amplitude of the input-output functions depending on the site of stimulation within t he CN. The results support the hypothesis that discrete activation of neuro nal subpopulations within the CN is possible with a penetrating multichanne l microelectrode.