Residual hearing after CI

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ref74

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It has become common to consider residual hearing completely lost after implantation. Anyway, you can find this statement in almost all the threads dealing with CI, but I have been not able to get any real data about that from the posts.
First, some practical considerations:
- if CI is working and the user is satisfied there is actually no need for that residual hearing.
- it is possible to read somewhere that saving the residual hearing is important for future stem cells treatment. But this is speculation, as nothing is clear with stem cells and I do not see any real scietific reason for that to be true.
- in theory if CI would turn into a failure that residual hearing can be used again with HAs, but I do not think there is any case of that, at least I was not able to find it.

Anyway, I was recently reading an extract form the national italian conference on CI of 2007 and got the info from the communication of Prof. A. Martini, one of the most important CI surgeon in Europe, about the residual hearing is conserved in something like 80% of patients with the new implants and surgery techniques, even more in the clinic where he works.

80% is not 100%, but it is still pretty different from "the residual hearing is lost after implantation". Then I searched the literature and I found some interesting articles. Among all I would like to share the following, that appears less optimistic than others, I think it is worth a look.

Acta oto-laryngologica
Volume 129
Issue 6
Pages 651-64

An evaluation of the preservation of residual hearing with the Nucleus Contour Advance electrode

Garcia-Ibanez Luis; Macias Angel Ramos; Morera Constantino; Rodriguez Manuel Manrique; Szyfter Witold; Skarszynski Henryk; Emamdjomeh Hessam; Baumgartner Wolf-Dieter

Extract:
RESULTS: In all, 36% of subjects demonstrated preservation of thresholds to within 10 dB of preoperative thresholds across the frequency range (0.25, 0.5, 1.0, 2.0 and 4.0 KHz) and for the low frequency range (0.25-1.0 KHz). Approximately two-thirds of subjects demonstrated preservation of preoperative thresholds to within 20 dB. Preservation of low frequency thresholds post-implant was shown to correlate moderately with cochleostomy site, being more likely for subjects with a site anterior-inferior to the round window but also possible with inferior locations; weakly with cochleostomy size, being more likely when smaller than 1.2 mm; and also with the use of Healon as a sealant and lubricant. Preservation of hearing thresholds across up to 4000 Hz was shown to correlate weakly with the use of suction following opening of the endostium and with bone dust contamination, both having a negative effect upon preservation, while no correlation was observed with the preservation of thresholds for low frequencies alone.




I believe this is very interesting and should be taken into account when speaking about residual hearing and CI. It is clear that saving the residual hearing is still an issue and it is a matter of the device used, but above all of the surgery itself. At the end, it is simply not true that 100% of CI destroy it completely.

From the presentation of Prof. Martini it was also possible to get some clues about a beneficial effect of electrical stimulation on the neural ganglion, potentially enhancing the residual hearing, moreover the potential use of the CI as a delivery instrument for some stem cells therapy... I was not able to get data from it, but I keep looking for (and possibly I could ask him directly)...
 
My daughter lost some residual hearing, but not all. Her audi says that he has one kiddo who wears a CI AND a hearing aid in the same ear because he has so much left.
 
what a minute??? When CI is inserted, don't they drain the fluid of the cochlear out? if so, it is useless to wear a hearing aid. How does the ear drum be able to vibrate without the fluid in the cochlear?

Unless it is a different type of CI / hearing aids like BAHA or the kind that deals with the bones which I don't know how that works at all.

I think I will stay away from audi who don't know what she is talking about.
 
What would be the point of getting a CI if he can do with a HA then? I assume he can't use both at the same time (where would the processor and the BTE fit at the same time?)
 
AlleyCat said:
What would be the point of getting a CI if he can do with a HA then? I assume he can't use both at the same time (where would the processor and the BTE fit at the same time?)
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He wears a body worn CI and a BTE hearing aid. His low frequency hearing is still very good, so he uses both.
 
Lighthouse77 said:
what a minute??? When CI is inserted, don't they drain the fluid of the cochlear out? if so, it is useless to wear a hearing aid. How does the ear drum be able to vibrate without the fluid in the cochlear?

Unless it is a different type of CI / hearing aids like BAHA or the kind that deals with the bones which I don't know how that works at all.

I think I will stay away from audi who don't know what she is talking about.
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No, YOU don't know what you are talking about, not the audiologist. There are many people whose residual hearing remains after surgery.
 
The whole question begs of this: If you have so much residual hearing that you prefer to stick with HAs and don't want to risk that, why get CI in the first place? Ive read CI blogs and most do lose their residual hearing, even those that keep their residual hearing, they lose 10-20db of that. You can't go back to HAs if you lose any residual hearing as you will no longer get enough benefit from HAs. Hybrid CI which is supposed to preserve good low frequency hearing is a failure, 90% either lose it right after CI or within a year.
 
FJ is right. There are most certainly cases where people retain their residual hearing following surgery. The one thing to remember is that not all of the cochlear fluid may be released. Insertion depth of electrodes also plays a part in this. Many people in the field of medicine, deafness and deafblindness are aware of this. Just yesterday I had someone ask me about my CIs and if I had any residual hearing. (I said no.) He doesn't know alot about CIs, but he did know enough to realize that some people do keep their residual hearing following surgery.
 
deafdude1 said:
The whole question begs of this: If you have so much residual hearing that you prefer to stick with HAs and don't want to risk that, why get CI in the first place? Ive read CI blogs and most do lose their residual hearing, even those that keep their residual hearing, they lose 10-20db of that. You can't go back to HAs if you lose any residual hearing as you will no longer get enough benefit from HAs. Hybrid CI which is supposed to preserve good low frequency hearing is a failure, 90% either lose it right after CI or within a year.
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Because you want improved clarity, and speech understanding. That is why.
 
Hear Again said:
FJ is right. There are most certainly cases where people retain their residual hearing following surgery. The one thing to remember is that not all of the cochlear fluid may be released. Insertion depth of electrodes also plays a part in this. Many people in the field of medicine, deafness and deafblindness are aware of this. Just yesterday I had someone ask me about my CIs and if I had any residual hearing. (I said no.) He doesn't know alot about CIs, but he did know enough to realize that some people do keep their residual hearing following surgery.
Click to expand...

I have very little residual hearing but then most of my loss was in the 115s dbs range across most feqs except the lowest feq before I had the CI surgery.

I can hear me snap my fingers if I put my fingers close to my right ear. I can't hear anything if I snap my fingers next to my left ear which is the implanted ear.
 
I try to reply to some of the expressed concepts.

First, the intra-cochlear fluid is NOT drained out. Actually the presence of the fluid in the cochlea (which is necessary to the tissues) is one of the limiting factor of pitch discrimination for CI users. Since the fluid is not pure water, but a saline solution (pretty concentrated), condictive, then, the electrical stimulation does not excite exclusively the closest ganglions, but the current is spread in the nearby, causing an excitation of a much bigger ensemble of spiral ganglions. This limit the fine accuracy of percieved pitches. There are some tricks to overcome this issue and many progresses have been done in the last models of implants. Nevertheless, this is why they do not produce implants with more than 22 electrodes, basically it is useless, because of this current spreading effect. There would not be any gain!
(I guess we can create some technical threads dealing with the basics of CI and HAs technology... OK, this is another story...)

Of course, I agree on the questionable concern of saving the residual hearing if you go with CI. If you decided to pursue this route it's pretty obvious the residual is not satisfactory... Why to go back then?

The hybrid CI is another story. And it is not true that it is a complete failure, although some failure of the first models are facts. In these devices the electrode array is definitely shorter (8 to 12 electrodes). The aim is covering just the high frequencies and using amplification for the lows, where the residual hearing is usable.
There are some recent papers on that. I try to look for them and post extracts here.

There is another problem with the measurement of residual hearing for CIers. The electrode passes through the middle-ear and it can interfere with the mechanical propagation of sound to the cochlea. Some experiments for new generation of electrodes minimizing this problem are actually under study, apparently. Moreover the cochleostomy, if not proper, can cause a defect of wave propagation in the cochlea. In other words, it is not the presence of the electrode itself in the cochlea that can cause the residual hearing loss, it's more on the surgical part.
 
Here it is. This is a clinical study of residual hearing preservation for hybrid CI. In this case from Med-El. As you can read the preservation is for 100% of patients, 45% complete preservation and measurable improved results for electric acoustic stimulation.
Does not seem to me as a total failure...


Acta oto-laryngologica (2009) Volume 129 Issue 4 Pages 372-9
A new electrode for residual hearing preservation in cochlear implantation: first clinical results
Gstoettner Wolfgang; Helbig Silke; Settevendemie Claudia; Baumann Uwe; Wagenblast Jens; Arnoldner Christoph

Abstract:
CONCLUSION: A so far unattained high rate (100%) of residual hearing preservation in cochlear implantation for electric-acoustic stimulation could be achieved using sophisticated surgical techniques in combination with the MedEl Flex EAS electrode. OBJECTIVES: This study aimed to gather first audiological and surgical results from the experience gained with the new MedEl Flex EAS electrode array. PATIENTS AND METHODS: Nine patients (aged 7.62-71.32 years) with profound high frequency hearing loss were supplied with this atraumatic electrode, which was designed to preserve residual hearing despite intracochlear insertion of an electrode array. All patients were implanted by the same surgeon. RESULTS: Hearing preservation was achieved in all patients (complete preservation 44.44%) after a mean follow-up period of 9.73 months. Mean monosyllabic test scores improved from 9% correct with the hearing aid alone to 48% with the cochlear implant and to 65% in the electric-acoustic mode.
 
This is a study for the function of middle ear after implantation. There is some work to do in this respect, too. This is also somethingwe can expect will be improved in the future.


The Journal of laryngology and otology (2009) Volume 123 Issue 7 Pages 723-9
Effect of cochlear implant electrode insertion on middle-ear function as measured by intra-operative laser Doppler vibrometry
Donnelly N; Bibas A; Jiang D; Bamiou D-E; Santulli C; Jeronimidis G; Fitzgerald O'Connor A

Abstract:
HYPOTHESIS: The aim of this study was to investigate the impact of cochlear implant electrode insertion on middle-ear low frequency function in humans. BACKGROUND: Preservation of residual low frequency hearing with addition of electrical speech processing can improve the speech perception abilities and hearing in noise of cochlear implant users. Preservation of low frequency hearing requires an intact middle-ear conductive mechanism in addition to intact inner-ear mechanisms. Little is known about the effect of a cochlear implant electrode on middle-ear function. METHODS: Stapes displacement was measured in seven patients undergoing cochlear implantation. Measurements were carried out intra-operatively before and after electrode insertion. Each patient acted as his or her own control. Sound was delivered into the external auditory canal via a speaker and calibrated via a probe microphone. The speaker and probe microphone were integrated into an individually custom-made ear mould. Ossicular displacement in response to a multisine stimulus at 80 dB SPL was measured at the incudostapedial joint via the posterior tympanotomy, using an operating microscope mounted laser Doppler vibrometry system. RESULTS: Insertion of a cochlear implant electrode into the scala tympani had a variable effect on stapes displacement. In three patients, there was little change in stapes displacement following electrode insertion. In two patients, there was a significant increase, while in a further two there was a significant reduction in stapes displacement. This variability may reflect alteration of cochlear impedance, possibly due to differing loss of perilymph associated with the electrode insertion. CONCLUSION: Insertion of a cochlear implant electrode produces a change in stapes displacement at low frequencies, which may have an effect on residual low frequency hearing thresholds.
 
There's still no point in CI(in my opinion) because stem cells has become available. I am getting it in about 3 years. I also see no point in hybrid CI because they can get similar results with transpositional HAs and avoid all the risks. Hybrid CI bypasses the missing high frequencies, but so does transposition!
 
deafdude1 said:
Hybrid CI bypasses the missing high frequencies, but so does transposition!
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If for some reason the hybrid CI does not work out as expected, a "regular" CI can be surgically implanted.

I know 3 people with hybrid CIs who are doing quite well and are very pleased with their implants.

As far as transposition aids are concerned, one important thing to remember is the training involved in learning how to hear with them. When I was evaluated for my first CI, I asked my audi if I could try transposition aids, but she discouraged me because of how difficult it would be for me to learn how to hear with them. I can't say whether or not that's true, but as far as my CI is concerned, I was able to start understanding some speech within 2 weeks following activation and was no longer using a tactile interpreter by 3 months post activation.
 
Hear Again said:
If for some reason the hybrid CI does not work out as expected, a "regular" CI can be surgically implanted.
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That's a 2nd surgery and taking risks a 2nd time. I actually know some people who decided to just get a regular CI. One of them had progressive hearing loss and would lose all his hearing in a few years. Another was borderline for a hybrid CI. A third didn't care that much to keep low frequency residual hearing and didn't want to bother with both CI and HA, just wanted CI and be done with it.

I know 3 people with hybrid CIs who are doing quite well and are very pleased with their implants.
Click to expand...

How much hearing did they have and at what frequencies? Did they even try transpositional HAs first? I know it doesn't work for everyone but if it works for you, it can get your speech up to where you won't qualify for any CI. I know a bunch of people with a ton of low frequency hearing and they are able to score around 60% speech with HAs, in some cases even unaided! Some of them are able to understand parts of a phone converstation unaided! If they wanna spend $50,000 and risk their hearing and other risks to go from 60% speech to 80% speech, their choice. Id be very happy if stem cells could give me as much unaided hearing as they have. To be able to hear without HAs better than I currently hear with HAs would be a dream!

As far as transposition aids are concerned, one important thing to remember is the training involved in learning how to hear with them.
Click to expand...

The training is the same for any CI as well.

When I was evaluated for my first CI, I asked my audi if I could try transposition aids, but she discouraged me because of how difficult it would be for me to learn how to hear with them. I can't say whether or not that's true, but as far as my CI is concerned, I was able to start understanding some speech within 2 weeks following activation and was no longer using a tactile interpreter by 3 months post activation.
Click to expand...

Neither of us have enough residual hearing for transposition. I do not expect any improvement in speech scores with transposition(yes, I tried it on my Phonak Naida HAs), after all my cochlea is dead to speech above 500-600Hz and dead to sounds above 1000Hz. No HA transports sounds this low. The lowest cutoff for any transpositional HA is 630Hz I believe. It may give me another 10% more access to environmental sounds but that's it. A CI would be far better in your case than transposition considering your degree of hearing loss. For people with more residual hearing than me, especially in the 1000Hz range, they can try transpositional HAs with a cutoff set to 630Hz or 800Hz. Ill be trying those HAs myself after stem cells gives me an improvement.
 
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