As I have had a cochlear implant I can tell you that in my case the process destroyed most of the residual hearing that I had left in the implanted ear. Newer electrode designs are made to preserve any residual hearing that the patient has. I also guess that the level of residual hearing left will vary from patient to patient. 

Dear Daniel,

Unfortunately the research project is in German language only. You said "there can be a change in residual hearing by inserting the electrode into the cochlea (speed, depth, ...)," I agree with you. Even difficult electrode insertion which require repeated trial of electrode insertion makes more deterioration of residual hearing & this deterioration will increase more & more with each trial of electrode insertion due to the repetition of intra-cochlear damage.

So safety of CI depends on experience of CI surgeon, normality of cochlea (of anatomic view:  patent, easily approached), type of the used CI device, post op rehabilitation & well of patient himself & his parents if the cochlear implantee is an infant.

Best regards.

Hazem

Dear Hazem,

The linked research description (the project is currently running) is all about modeling a cochlea including an electrode. Especially, this focuses on which electrode and insertion depth to choose in case of an EAS (= Hybrid) CI system.

Best regards,

Daniel

What we've learned from our clinic and other studies is that there is an anticipated loss of approximately 10 dB just from the electrode insertion. However, that can be more, or less, depending upon the surgeon, the patient and the electrode array, I believe. 

of course, but what I'm looking for is the influence of the electrode array itself, not through the insertion process.

does anyone have results for this topic?

What I currently have is anecdotal. And I need to follow up further to be sure it's accurate.

Daniel, this article may be helpful:

Article Hearing preservation and cochlear implants according to inne...

Dear Henrique,

this is also very interesting, sothank you very much, but sadly as I could see it's again just about the influence through the insertion process and not about the influence through the electrode being inside the scala tympany. What I mean is fluid mechanics.

Dear Daniel, 

you have a great point! Probably there is something related only t the electrode/array itself, but there is no scientific outcomes related to this topics. The companies does not reveal this issues ou they also do not have those informations.

This could be an interesting research paper!

Best Regards

Tremendously interesting question now that ears with very good low-mid frequency hearing are being implanted and measurement of a conductive component to the hearing loss pre- and post-implantation is meaningful. Many early reports of threshold changes pre- vs. post-op when trying to preserve hearing did not include bone conduction thresholds. I just uploaded some data I presented several years ago about the change in static admittance by tympanometry at intervals pre- and post-implantation. Study of stiffness, RW membrane changes, fluid dynamics needed -- and bone conduction as well as air conduction thresholds. 

Dear Daniel,

interesting question for sure!

Maybe Dominik Obrist (U Bern, https://www.researchgate.net/profile/Dominik_Obrist2) has some insight on this topic. He worked with his PhD-students @ ETH Zurich on CFD and FSI of the cochlear and is possibly continuing this research. See also the thesis and papers by Elisabeth Edom (http://e-collection.library.ethz.ch/view/eth:8548) and Bernhard Grieser (all former IFD-ETHZ).

Maybe contacting Dominik directly is an option.

Best,

Tobias

Dear Daniel,

maybe this is a helpful link? http://memro2015.org/UserFiles/file/Abstract%20Book.pdf

see: A3-8) The impact of a cochlear implant electrode array on middle ear transfer function.

Best regards

As I have had a cochlear implant I can tell you that in my case the process destroyed most of the residual hearing that I had left in the implanted ear. Newer electrode designs are made to preserve any residual hearing that the patient has. I also guess that the level of residual hearing left will vary from patient to patient.