Fitting Methods by EAS Patients
Conditions
Keywords
Cochlear Implant patients, Residual hearing in the low frequency range, EAS, fitting methods, electrocochleography
Brief summary
The aim of this clinical study is to investigate how the fitting of an EAS (electrical acoustic stimulation) based on electrocochleography (ECochG) thresholds compares to fitting based on pure tone audiogram thresholds in terms of speech intelligibility in quiet and noise. The personal feedback from the study participants regarding the question of better fitting and the resulting sound quality should also be included in the analysis.
Detailed description
As the indications for Cochlear Implant (CI) Surgery expand to also include hearing impaired patients with some residual hearing in the ipsilateral (to be implanted) ear, residual hearing preservation during the surgical intervention becomes even more important. It is also known from the literature that patients will benefit from having good residual acoustic hearing after CI-Implantation in terms of the sound quality. This is particularly so for speech comprehension in noise as well as for music perception with the CI. Present-day clinical Sound Processor programming software provides Electric Acoustic Stimulation (EAS) to account for preserved residual hearing. For an optimized EAS fitting, it is postulated here that optimal conditions are achieved when the electric and acoustic stimulation do not overlap. To achieve this, the acoustic stimulation ought to be limited to only regions where there is still useful acoustic hearing, while the electric stimulation should also be restricted to regions where there is no longer significant useful acoustic hearing. In the Maestro clinical software, the threshold for significant useful acoustic hearing is set to 65 dB Hearing Level (HL). This then determines the cut-off frequency between the acoustic and electric stimulation regions. The standard clinical Maestro software computes this cut-off based on a regular pure tone audiogram (PTA) which has been manually stored in the software. However, it is arguable that this does not always represent an accurate cut-off frequency required for optimal fitting because the audiogram thresholds themselves are subjective in nature and can often vary in a test-retest situation, depending on the attention and reaction times of the patient. It has been reported that the unaided thresholds do not play a significant role in the EAS fitting. In this respect, it may be more accurate and beneficial to use objective measures such as electrocochleography (ECochG) to determine the thresholds of the residual hearing. The current family of Med-El Cochlear Implants are equipped with the capability to perform ECochG measurements using the implant's own intracochlear electrodes within the scala tympani. The measurements can also be conducted intraoperatively or postoperatively. This intracochlear ECochG feature of the implants therefore allows us to objectively determine the residual hearing thresholds. The aim of this study is to discuss the advantages of objective fitting of the EAS compared to subjective fitting using a PTA with respect to speech intelligibility in quiet and in noise. The personal feedback from the study participants regarding the question of better fitting and the resulting sound quality should also be included in the analysis. From the existing literature, it is not expected that there should be any significant gender effects. This also does not belong to the primary aims of this study and we will not be investigating this aspect.
Interventions
OTHERThe objective fitting method of the EAS based on the thresholds of electrocochleography is the intervention of our study.
Measured ECochG thresholds will be used in the initial EAS fitting in period 1 for sequence B. For sequence A, the ECochG-based EAS fitting (with up-to-date ECochG thresholds) will take place three months later at the beginning of period 2.
OTHERThe subjective adjustment of an EAS based on thresholds from the pure tone audiogram.
The control intervention is the subjective EAS fitting based on PTAs. This is provided to sequence A at the beginning of period 1 baseline and to sequence B at the beginning of period 2.
Sponsors
Luzerner Kantonsspital
MED-EL Elektromedizinische Geräte GesmbH
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 85 Years
Healthy volunteers
No
Inclusion criteria
1. Patients aged between 18-85 years. 2. Cochlear Implant (CI) candidates with measurable post-operative low-frequency residual hearing (125Hz \<65dB, 250Hz \<65dB, 500Hz \<65dB). 3. Only patients with MED-EL EAS. 4. Written informed consent must be obtained prior to study start.
Exclusion criteria
1. Patients with cognitive impairments who, as a result, lack the capacity to make decisions. 2. Uncooperative patients regarding pure tone audiometry thresholds measurements. 3. Morbus Menière or intracochlear/ vestibular schwannoma
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Speech Recognition Threshold (SRT50) | Three months after EAS fitting | The primary outcome measure is the Speech Recognition Threshold (SRT50) at three months after EAS fitting (either objective or subjective EAS fitting in a cross-over design). The SRT50 measures speech understanding in noise and is defined as the Signal-to-Noise Ratio (measured in dB SNR) which yields 50% speech understanding, as determined by the OLSA test. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Subjective level of auditory benefit | Three months after EAS fitting | A secondary outcome measure is subjective level of auditory benefit at three months after EAS fitting (either objective or subjective EAS fitting in a cross-over design), as determined using the HISQUI-19 (Hearing Implant Sound Quality Index) questionnaire. |
| Subjectively preferred EAS fitting method | at the end of the study, six months after baseline | The subjectively preferred EAS fitting method at the end of the study will be examined. |
| Post-operative ECochG and PTA tresholds | Three months after EAS fitting (either objective or subjective EAS fitting) | Post-operative ECochG and PTA thresholds at three months after EAS fitting (either objective or subjective EAS fitting in a cross-over design). |
Contacts
CONTACTArmina Kreuzer, Dr.
CONTACTWai Kong Lai, Dr.
PRINCIPAL_INVESTIGATORArmina Kreuzer, Dr.
Luzerner Kantonsspital
Outcome results
None listed