Results of the round window electrical stimulation in 460 cases of total deafness.

In order to avoid false and quantitatively unprecise responses the stimulating electrode must be directly placed on the round window membrane. That necessitates a transmeatal approach removing the eardrum, which is commonly achieved under local anesthesia. The positive response is subjectively easy to identify; it may be objectively registered by means of brain stem evoked responses; this registration is indispensable in case of children who need general anesthesia. This positive response signifies that some cochlear nerve fibers are still present, and therefore that the rehabilitation of the cochlear implant is possible. Among the 460 totally deaf, stimulated patients, more than 93% of them presented a positive response. The threshold level voltage value represents a statistically significant representation of the functional value of the electrode nerve interface. The features of the tone decay tests, which may be also subjectively or objectively performed, present important data which may be used to predict the clinical results that can be obtained by the cochlear implant.