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)...
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)...