[Experience with electrostimulation of the acoustic nerve before cochlea implantation]

The electrical stimulation of the acoustic nerve plays an essential role in the selection of patients for cochlea implantation. The performance of a deaf ear under the conditions of electrical stimulation can be assessed by means of the pre-operative promontory test using a transtympanic needle electrode. Five components of this test were applied to 48 patients: the determination of perception threshold and upper comfortable level for pulse and burst stimulation, the pitch test, the temporal difference test and the gap detection test. The mean values emerging from these examinations may be useful as guidelines for the interpretation of individual results. A cross correlational analysis of the data was performed in order to eventually discover redundancies among the different test components. Indeed, the threshold values for pulses of a given duration are highly correlated to those for bursts of the corresponding frequency. One of these tests may therefore be eliminated for routine test purposes. Similarly, the assessment of time resolution capabilities with the temporal difference limen test yields results which show a strong correlation with those of the gap detection test.