Clinical Trial Details
— Status: Terminated
Administrative data
| NCT number |
NCT03025386 |
| Other study ID # |
9735 |
| Secondary ID |
|
| Status |
Terminated |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
May 18, 2017 |
| Est. completion date |
June 2, 2022 |
Study information
| Verified date |
January 2023 |
| Source |
University Hospital, Montpellier |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
A cochlear implant is a device for the rehabilitation of severe to profound hearing loss.
Despite the standardization of surgical procedures and rehabilitation, speech discrimination
performance varied significantly in cochlear implant users and could be improved by early
individualized cares. However, there is no objective method yet to evaluate phonemes
discrimination, especially in infants, which account for more than half of the indications
for implantation. In electroencephalography (EEG), it is possible to highlight the
discrimination of auditory stimuli studying the wave of MisMatch Negativity (MMN). In this
work, this study propose to use the MMN as an objective vocal audiometry method to evaluate
the ability to discriminate phonemes, the smallest units of oral language, in adult cochlear
implant users.
Description:
Context of the study Cochlear implant is an effective and recognized long-term solution for
people with severe to profound neurosensory hearing loss. Its principle is to collect sounds
of the environment, to analyze them, to transform them and, using an electrodes array placed
in the cochlea, to transmit them back to the auditory nerve by electrical impulses. With
practice, these are integrated and then recognized by the brain that associates a meaning.
For normal hearing persons, speech recognition involves several time and frequency cues that
the ear is able to decode. However, the cochlear implant distorts and alters some of these
speech cues; the implant easily retransmits the temporal features but the frequency ones are
much deteriorated. Thus, cochlear implant users preferentially use the temporal cues, which
provide truncated and incomplete information, which often results in a lower quality
understanding. Thus, learning or re-learning the language through the cochlear implant is
difficult for the young deaf child as for the deaf adults.
The cochlear implant setting is essentially based on perceptual features. A detection
threshold and a comfort level are fitting according to the perceptions of the patient and
several objective tools. These provide important information but do not on the validity of
the setting to ensure optimal speech understanding. The High Authority of Health suggests
speech therapy in the overall rehabilitation of cochlear implant users. This aims to develop
auditory skills according to four major perceptual axes: detection, identification,
discrimination and understanding of sounds.
Despite these cares, cochlear implant users have speech recognition scores lower than those
of normal-hearing people and have heterogeneous performances. Deafness etiology (auditory
neuropathy, demyelization, ...), integrity of the auditory nerve, position of the electrode
array in the cochlea, cognitive abilities, age implantation, duration of hearing loss,
quality of cortical integration, cerebral plasticity, speech therapy, the family environment,
implant fitting could affect subject performances.
Difficulties in speech understanding may be related to poor discrimination of phonemes, the
smallest units of oral language. These phonemic confusions can be tested in adults by several
tests such as the Phonetically Balanced Kindergarten test (PBK). However, in the very young
child, childs with polyhandicap or the disabled adult, the evaluation of the language is more
delicate and needs a long term.
Several electrophysiological techniques would nevertheless make it possible to objectively
demonstrate the ability to discriminate phonemes in one measure. For example, the mismatch
negativity wave (MMN) reflects a cognitive process showing the discrimination of two
different sounds by the auditory system. It is measurable in adults and children,
automatically and regardless of the level of vigilance. In this study use a MMN protocol to
highlight phonemic discrimination capacities and then link them to subjective performances in
the adult cochlear implant users. The first objective is to establish in these users a
concordance between the amplitude of the MMN and a test of discrimination of logatoms, both
highlighting the capacities of auditory discrimination. The second is to establish a
concordance between the amplitude of the MMN and the scores obtained with the PBK.
Method
A forced choice test will evaluate the discrimination of the most confusing logatoms in the
cochlear implant users, and representative of the French language. The following couples were
selected:
- " fa " vs " sa "
- " la " vs " na "
- " pan " vs " pa "
- " pa " vs " ta "
- " pon " vs " po " Each couple of logatoms will be tested twenty times. If the score is
greater than 16/20, the discrimination of logatoms pair will be considered positive. The
test, carried out using Matlab MathWorks software, was automated so that the patient
could do it without the intervention of the experimenter; It remains under its
supervision in order to verify that the test is proceeding normally.
Obtaining the MMN requires a paradigm called "oddball", during which a "frequent" stimulus is
emitted 80% of the time and a second stimulus called "deviant" is presented only 20% of the
time. The high repetition rate of the frequent stimulus ("pa" for example) creates an
electrophysiological baseline. When a deviant stimulus ("ba" for example) appears, this
introduces a break in the electrophysiological baseline which results in the appearance of a
so-called mismatch negative wave, the MMN. It shows the discrimination by the auditory system
of two different stimuli. By studying the amplitude of this wave, it is possible to evaluate
the quality of discrimination. A low or zero amplitude means that the subject did not
discriminate the two logatoms. Conversely, the higher the amplitude, the greater the
discrimination quality is. The wave latency can also be a variable to be observed. The
earlier it is, the more it marks the ease of discrimination.
For each subject, the concordance with the score in the logatoms discrimination test will be
analyzed separately for each pair. This will make it possible to evaluate the consistency of
this concordance according to the pairs of tested logatoms. The optimal threshold of the MMN
amplitude to identify subjects with good auditory discrimination is not yet known (innovative
method). The first stage of our analysis will be to search for this threshold by constructing
an receiver operating characteristic (ROC) curve to best distinguish patients with good and
bad auditory discrimination in the test of the logatoms (choice of the threshold by the index
of Youden). This threshold will then be used to classify subjects as having good or poor
auditory discrimination according to the EEG. The agreement between the results of the EEG
and the test of logatoms discrimination will then be analyzed by the calculation of a Kappa
coefficient.
The PBK test will be used to evaluate an overall comprehension score. This test consists of 4
lists of 50 words respecting the occurrence of the phonemes of the French language and using
mono- and bi-syllabic words. A score above 70% is accepted as a good performance. The
concordance between the results of the EEG procedure for each logatoms (good and bad auditory
discrimination defined as above) and the result of the PBK test will be analyzed using Kappa
coefficients.
Finally, different secondary data will be collected: type of cochlear implant (mark, internal
and external part), duration of implantation in months, etiology, data related to the implant
setting (number of active electrodes , Thresholds C and T, IDR, automatic functions like
SCAN, ADRO, ...)
