The Second and Subsequent Sessions of the Med-El Cochlear Implant Fitting

In the previous article [1], we briefly described the procedure for the first switch on and the first session of fitting of the Med-El cochlear implant...

stapedial reflexes are recorded have a loudness rating in the GOOD-LOUD range.

Parameters of Stimuli and Method of Stimulation
The duration of the electrical test stimuli is 300ms. In this work, we use stimulation with single pulses and stimulation of separate channels in SWEEP mode with an interval between sequential stimuli of 300 ms, as well as sequential stimulation of all channels in SWEEP mode with an interval between stimuli of 600 ms. Such an interval is used during registration of a stapedial reflex. The amplitude of stimuli is equal to the C-levels set in each channel. An amplifier, headphones, and stepped noises for conducting SHCHUP [2,3] are ready.

Fitting
We open the working (everyday) program 21. In the further fitting process, we will change the C-levels in this program and hereinafter we will call it a test program. We reduce the MCL levels of program 21 by 2 page down (according to C-levels, it will be less than reflex program 22). We remind (we show with gestures) to the child that when we will press the keys of the keyboard, he will hear either a single signal or their sequence. We demonstrate the child a single and SWEEP stimulation through separate channels.
We give a single stimulus to the middle electrode with the number 5-7, where the patient hears the middle frequencies. We observe the child and ask: "How? Heard?" The child responds. It is very possible that he will agree. If everything is normal, then we apply single stimuli to other electrodes. "Is everything all right?" We apply stimulus sequences (SWEEP) to single electrodes. "Is everything all right?" We set the interval of 600ms and apply the SWEEP stimuli sequentially across all channels. We will sometimes use sequential SWEEP stimulation of all channels with an interval of 600ms -it is interesting for the child. We remind the meaning of the pictures used in categorical loudness scaling (CLS) [7] and ask the child to show how he hears? The child shows. We ask: "Can I increase loudness?" Child agree: "You can." We increase by 3 steps and give single and SWEEP stimuli through separate channels. "Is everything all right?" By agreement with the child, we continue the parallel increase in the C-levels of the test program, conducting single and SWEEP stimulation on separate channels. We carefully monitor the reaction of the child. We ask to show the loudness in the pictures.
When approaching the MCL levels of the old work program 21, we save the test program under No. 23.

Registration of Threshold Levels of The Stapedial Reflex
Next, we proceed to the measurement of threshold levels of the stapedial reflex in accordance with the previously described procedure [6]. We set the interval between stimuli to 600 ms.
We equip the child for registration of the reflex and perform tympanometry. We open the reflex program 22 and reduce the C-levels in all channels by 3 steps. We provide SWEEP stimulation with interstimulus interval of 600ms across all channels. "Is everything okay?" Starting from these C-levels, we define the C-levels where the threshold values of the stapedial reflex are marked and save the program with these threshold C-levels under the number 24. Under the number 24CCPP, we save the reflexprogram with the parameters of the tympanogram; CC-compliance, PP-pressure at the point of max compliance [6]. For the history.
We dismantle the registration unit, release, and praise the child.

Categorical Loudness Scaling -CLS [7]
We open the test program 23. We again remind the meaning of the pictures used in the CLS [7]. Previously, the child has already shown his ability to evaluate the loudness. We conduct CLS in full.
We present electrical stimuli in the SWEEP mode on a single channel with an interval between stimuli of 300 ms. Decrease-increase C-levels, the child shows their loudness ratings in accordance with our changes in C-levels of stimuli. We repeat the CLS on a few channels. Praise the child.

The final stage of fitting -SHCHUP [2,3].
As you know, objective measures, for example, threshold C-levels of the stapedial reflex, play a small role as indication of the optimal MAP profile [8] and therefore it is necessary to use subjective estimates to determine the MCL levels. As shown in the study of Sherlock P, Formby C [9] a simple loudness discomfort level estimate of loudness discomfort is an effective and valid clinical measure for characterizing the "threshold of discomfort". This is why we developed our SHCHUP method in which we use special step noises [2,3]. With help of the SHCHUP, we determine the C-levels of electrical stimuli at which the child perceives sound stimuli of 106 dB SPL at the level of discomfort threshold, i.e. Step noises are ready. Turn on the amplifier. We connect the antenna of the implant to a long wire, place it on the patient's head, and the processor under the circumoral embouchure of the phone, to which we will apply SPL-controlled step noises. We activate the test program 23 and conduct the SHCHUP in accordance with the previously described procedure [2.3]. We compare the MCL levels of the old working program 21 and the C-levels of our test program, corrected according to the results of the SHCHUP. In those channels where C-levels of a test program are lower than the MCL levels of the old work program 21 we raise C-levels to the MCL levels of work program 21. We do not change C-levels of our test program where these C-levels above the C-levels of the old work program 21.
We save the test program under number 25. Now it is a new work program and C-levels slightly differ from the old work program 21.
we check the new work program 25 with a live voice, sometimes slightly increasing the loudness of the conversation. Setup is complete. We release the child from the equipment. Thank him. I shake his hand.

Creating of Configuration
Child clearly chose the working program after the first session