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• Reduced evoked theta activity in the deaf.
• Reduced theta-gamma and alpha-gamma cross-frequency couplings in the deaf.
• Stronger delta-alpha coupling in the deaf.
Abstract
Neurons within a neuronal network can be grouped by bottom-up and top-down influences using synchrony in neuronal oscillations. This creates the representation of perceptual objects from sensory features. Oscillatory activity can be differentiated into stimulus-phase-locked (evoked) and non-phase-locked (induced). The former is mainly determined by sensory input, the latter by higher-level (cortical) processing. Effects of auditory deprivation on cortical oscillations have been studied in congenitally deaf cats (CDCs) using cochlear implant (CI) stimulation. CI-induced alpha, beta, and gamma activity were compromised in the auditory cortex of CDCs. Furthermore, top-down information flow between secondary and primary auditory areas in hearing cats, conveyed by induced alpha oscillations, was lost in CDCs. Here we used the matching pursuit algorithm to assess components of such oscillatory activity in local field potentials recorded in primary field A1. Additionally to the loss of induced alpha oscillations, we also found a loss of evoked theta activity in CDCs. The loss of theta and alpha activity in CDCs can be directly related to reduced high-frequency (gamma-band) activity due to cross-frequency coupling. Here we quantified such cross-frequency coupling in adult 1) hearing-experienced, acoustically stimulated cats (aHCs), 2) hearing-experienced cats following acute pharmacological deafening and subsequent CIs, thus in electrically stimulated cats (eHCs), and 3) electrically stimulated CDCs. We found significant cross-frequency coupling in all animal groups in > 70% of auditory-responsive sites. The predominant coupling in aHCs and eHCs was between theta/alpha phase and gamma power. In CDCs such coupling was lost and replaced by alpha oscillations coupling to delta/theta phase. Thus, alpha/theta oscillations synchronize high-frequency gamma activity only in hearing-experienced cats. The absence of induced alpha and theta oscillations contributes to the loss of induced gamma power in CDCs, thereby signifying impaired local network activity.
Purpose: The treatment with a cochlear implant (CI) is the gold standard in therapy of patients with profound hearing loss or deafness. Successful hearing rehabilitation with a CI is a complex, multi-stage process. In medicine, “Clinical Practice Guidelines” (CPG) are widely accepted for the standardization of such processes. These are supplemented by medical registries in which data regarding the treatment can be collected and evaluated. The aim of this paper is to identify currently existing CI-related CPGs and registries in Europe.
Methods: Between 01/2021 and 06/2021, 42 countries on the European continent, including the United Kingdom, Russia and Turkey, were screened using an internet search (search engine: Google) and a key word search in the Pubmed database. Search terms were the respective country name combined with the following terms: “Cochlear Implant”, “CI”, “Cochlear implant clinical practice guideline”, “CI Guideline”, “Cochlear Implant Registry”, “CI Registry”, “Ear nose throat society”. The internet search was conducted in English as well as in the corresponding national language. The objective was to identify a CI-related CPG or registry.
Results: A CPG was found in 16 of 42 (38%) countries. In terms of population, this accounts for 645 million out of 838 million people (77%). A registry existed in 4 of the 42 (10%) countries assessed. This corresponds to 102 million out of 838 million (12%) people. In total, 4 out of 42 countries (10%) had both a CPG and a registry.
Conclusion: Our work shows numerous efforts in Europe to standardize CI care at the national level. While most people in Europe already live in countries with a CPG, this is not the case for CI registries. European-wide consensus on CPGs or registries does not yet exist. The present study thus provides a first assessment of the distribution of CI-related CPGs and registries.
Long-term effects on the quality of life following cochlear implant treatment in older patients
(2022)
Purpose: Even in older patients, hearing rehabilitation with a cochlear implant has become an established method for deafened or severely hearing-impaired patients. In addition to the hearing improvement, numerous other effects of CI treatment can be observed in clinical routine. In the literature, there is multiple evidence for a rapid and significant improvement in quality of life with CI treatment. The aim of this study was to evaluate the long-term effects of hearing rehabilitation using CI on the quality of life in older patients (≥ 65 years).
Methods: This prospective cross-sectional study examined 84 patients between the age of 65 and 101 years who received unilateral CI treatment for the first time between one and 10 years ago. The World Health Organization Quality-of-Life Scale-Old (WHOQL-OLD) was used to determine the quality of life. The study cohort was divided into three groups to compare the quality of life over time: group I (1–3 years after CI treatment), group II (4–6 years after CI treatment), and group III (7–10 years after CI treatment). In addition, the data from this study were compared with the results of our previous study (Issing et al. 2020) in which we focused on the first 6 months after CI treatment.
Results: In all three groups, there was a significant improvement in monosyllabic discrimination within 1 year after CI fitting (p > 0.001). No significant differences were found between the three groups. There were no significant differences between the three groups in the WHOQOL-OLD total score (p = 0.487) or any of the other six facets. Moreover, no significant differences were found compared to the study group of our previous study 6 months after CI treatment.
Conclusion: This study demonstrates the long-term stability of the improved quality of life following unilateral CI treatment in patients aged 65 years or older.
Purpose: Monocentric, prospective study to investigate whether concomitant support of cochlear implant (CI) patients by CI-trained otolaryngologists and application of a standardized head bandage can minimize potential complications during magnetic resonance imaging (MRI).
Methods: Thirty-seven patients with 46 CIs underwent MRI with a prophylactic head bandage. All participants and the otolaryngologist at the CI center completed pre- and post-MRI questionnaires documenting body region scanned, duration of MRI and bandage wear, field strength during the scan, and any complications. If pain was experienced, it was assessed using a visual analog scale (1–10).
Results: MRI was performed without adverse events in 37.8% of cases. Magnet dislocation requiring surgical revision occurred in 2% of cases. Pain was reported in 86% of cases, often due to the tightness of the dressing. Patients with rotating, MRI-compatible magnets reported significantly less pain than participants with older-generation implants. In 11% of cases, the MRI was discontinued.
Conclusion: Serious complications during MRI in cochlear implant patients are rare. Pain is the most common adverse event, probably mainly due to the tight bandage required by most implant types. With newer generations of magnets, these patients experience less pain, no dislocation of the magnets, and no need for bandaging. Although magnet dislocation cannot be completely prevented in older generations of implants, it appears to be reduced by good patient management, which recommends examination under the guidance of physicians trained in the use of hearing implants.