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First clinical experience in the use of triphasic stimulation pulses in patients with facial stimulation
18 April 2018 (online)
Most CIs use biphasic rectangle pulses to stimulate the auditory nerve. The amount of charge transmitted by the pulse, which leads to the perception of a pleasant loud hearing impression, is individual and different for each cochlear electrode. The amount of charge is determined by the amplitude and duration of the pulse. In some cases, this stimulation also involves unwanted irritation of the facial nerve, which usually manifests itself in a visible and palpable twitching of the eyelid or the angle of the mouth. In studies by Bahmer et. al. (2016), in some cases stimulation of the facial nerve could be reduced or prevented by the use of stimulation with triphasic pulses. The possibility of using triphasic stimulation pulses has also been possible for some time in the clinical routine. Initial clinical experience is reported.
Material and Method:
Up to now eleven patients have been provided with hearing programs based on triphasic pulses. The main success for the clinical routine is the reduction of the irritation of the facial nerve. The result is categorized in preventing, reducing, unchanged or amplified. In addition, two individual cases are analyzed which attempt to derive possible causes for the success or failure of the tripasic stimulation.
Results and Conclusion:
In eight out of the eleven patients the facial nerve stimulation was reduced or prevented by the use of triphasic pulses. The speech intelligibility test, that were conducted in some cases, partially showed an improvement in speech understanding with this more adequate stimulation. However, a patient with a particularly low stimulus threshold could not be helped. In the case of facial stimulation, the conversion to stimulation with triphasic pulses is recommended.