The Berlin cochlear implant--surgical concept.

The extent of channel interactions using monopolar extrascalar stimulation probably limits the number of independently acting electrodes of a cochlear implant to three. Comparison of psychoacoustic and histopathological findings led to the conclusion that stimulation of the neurons in the upper basal and the second coil is of greatest benefit to the patient. By using a middle fossa approach, access to the upper basal coil and the second coil is possible without destruction of middle ear structures. The danger of infection is probably reduced. Using an additional external round-window electrode, a device providing three different stimulating electrodes can be applied.