The German cochlear implant registry: one year experience and first results on demographic data.

PURPOSE: Clinical registries have great potential for quality control of medical procedures regarding the indications, therapeutic processes and results, including their possible complications. This is particularly true when providing patients with severe hearing loss or deafness with a cochlear implant (CI). This treatment represents a lifelong care process that requires continuous quality control over time. On the initiative of the Executive Committee of the German Society of Otorhinolaryngology (Deutsche Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie e.V., DGHNO-KHC), a national German CI registry (Deutsches Cochlear Implant Register, DCIR) was established in January 2022. This article focuses on the first demographic and baseline data of the DCIR. METHODS: The DCIR covers the complete therapeutic process from indication, surgery, fitting and lifelong aftercare in CI therapy. By the end of 2022, 75 hospitals in Germany had agreed to contribute to the DCIR. RESULTS: During the year 2022, 63 hospitals actively contributed data to the DCIR. Pseudonymized data from 2,292 CI implantations (2,176 primary implantations, 99 explantations with immediate re-implantations and 17 re-implantations following an earlier explantation) in 2,108 patients were documented. Cochlear implantation was accomplished in 1,807 adults (≥ 18 years) and 301 children (< 18 years). Fourty patients (1,9%) were children < 1 year of age and 55 (2,6%) were patients > 85 years. From the total of 2,292 implantations, 226 (9.9%) were performed as simultaneous bilateral implantations (CI implantation in both ears of 113 patients on the same day of surgery) and 412 implantations (19.1% of 2,162 implantations with data provided on the contralateral ear's hearing status) were in patients with single sided deafness (normal hearing in the contralateral ear). In addition, the reported complications in 2022 were also evaluated. Seven reports (0.4%) of mild to moderate severe facial nerve dysfunctions were documented. No reports of severe or total facial nerve dysfunction (House-Brackmann grade V/VI), meningitis or death related to CI therapy were documented. CONCLUSION: Although still in the start-up phase, these initial DCIR data already provide an interesting first insight into the demographic structure and baseline data of CI therapy in Germany. The successful implementation of the DCIR represents an important step towards continuous quality control of CI care.

Implantation and reimplantation: epidemiology, etiology and pathogenesis over the last 30 years.

INTRODUCTION: Due to the increasing number of cochlear implant (CI) recipients, growing indications, and the aging population, the reimplantation of CI recipients has become a focus of attention. The aim of this study is to examine the causes, timing, and postoperative speech understanding in a large cohort over the past 30 years. METHODS: A retrospective data analysis was conducted on over 4000 CI recipients and 214 reimplanted children and adults from 1993 to 2020. This involved collecting and comparing data on causes, manufacturer information, and demographic data. In addition, a comparison of speech understanding in Freiburg monosyllables and numbers before and after reimplantation was carried out. RESULTS: Children did not exhibit elevated rates of reimplantation. The overall reimplantation rate in the entire cohort was 5%. The CI overall survival rate after 10 years in the entire cohort was 95.2%. Device failure was the most common reason for reimplantation, with 48% occurring within the first 5 years after implantation. The second most common reason was medical complications, with the risk of reimplantation decreasing as more time passed since the initial implantation. There were no significant differences in Freiburg numbers and monosyllable comprehension before and after reimplantation, both in the overall cohort and in the subcohorts based on indications. Even a technical upgrade did not result in a significant improvement in speech understanding. DISCUSSION: There was no significant difference in the frequency of reimplantation based on patient age, especially when comparing children and adults. Device failure is by far the most common indication for reimplantation, with no significant difference in implant survival between manufacturers. Patients most often choose the same manufacturer for reimplantation. The likelihood of reimplantation decreases with increasing time since the initial implantation. The indication for reimplantation should be carefully considered, as on average, no improved speech understanding is achieved, regardless of the cause, even with a technical upgrade.

Insertion of a second electrode array-a rare complication of CI reimplantation.

Due to a technical defect or a medical indication, it may be necessary to explant a cochlear implant. This case report shows that there is the risk of encountering a nonremovable electrode array-as described here from the scala tympani-during cochlear reimplantation. In the present case, insertion of a second electrode array into the free and nonobstructed scala vestibuli was successful. Nonetheless, the indication for reimplantation must be carefully considered, especially in patients with tolerable limitations with little or no loss of speech understanding. Furthermore, surgery should not be performed solely because an implant upgrade is desired.

[Insertion of a second electrode array-a rare complication of CI reimplantation. German version]. / Insertion eines zweiten Elektrodenträgers ­ eine seltene Komplikation bei CI-Reimplantation.

Due to a technical defect or a medical indication, it may be necessary to explant a cochlear implant. This case report shows that there is the risk of encountering a nonremovable electrode array-as described here from the scala tympani-during cochlear reimplantation. In the present case, insertion of a second electrode array into the free and nonobstructed scala vestibuli was successful. Nonetheless, the indication for reimplantation must be carefully considered, especially in patients with tolerable limitations with little or no loss of speech understanding. Furthermore, surgery should not be performed solely because an implant upgrade is desired.

Evaluation of insertion quality of a slim perimodiolar electrode array.

OBJECTIVES: The influence of cochlear morphology and electrode array design on scalar position and dislocation rates is of great interest in CI surgery. The aim of this study is to evaluate scalar position and specific points of dislocation in relation to cochlear morphology in patients implanted with a new slim perimodiolar electrode array. MATERIALS AND METHODS: Patients were implanted using the slim modiolar electrode array (= SMA) (= 532/632 electrode array of Cochlear™). Postoperative imaging was performed via cone beam computed tomography (CBCT) and the scans were analyzed regarding cochlear morphology (distances A and B and cochlear height), scalar location of the electrode array, basal insertion depth and apical insertion angle. Furthermore, electrode array design and surgical protocols were evaluated. RESULTS: 81 ears implanted with the SMA were retrospectively included. We evaluated 3 electrode array tip fold over intraoperatively via X-ray imaging and performed revision during the same surgery. The CBCT scans showed 76 initial scala tympani (ST) insertions without dislocation. Two ears showed a dislocated array, one at 77° and the other at 163°. Three arrays were inserted into scala vestibuli (SV) via cochleostomy. These patients showed no signs of obliteration. Cochlear morphology showed no influence on angular insertion depth and scalar position. CONCLUSIONS: The SMA showed a very low rate of scalar dislocations due to its slim electrode array design (2.7%). We could find a learning curve regarding the handling and the risk of dislocation and tip fold over with this electrode array. The rate of intraoperative tip fold over detection via X-ray imaging was 3.7%. Therefore, we highly recommend X-ray imaging and transimpedance matrix measurements within the surgery protocol. Scala vestibuli insertions happened in patients with cochleostomy only. We could identify two specific points of dislocation depending on electrode array design.

Scalar position, dislocation analysis and outcome in CI reimplantation due to device failure.

OBJECTIVE: Due to increasing indication for cochlear implantation (CI), reimplantation and technical upgrades their consequences are a special focus in CI surgery research. The aim of this study is to examine the indication and influences on both morphological position of the electrode array and audiological outcome following reimplantation. DESIGN: This is a retrospective analysis of adult CI patients reimplanted between 2004 and 2019. We evaluated the scalar position in pre- and postoperative cone beam computed tomography (CBCT) after CI and reimplantation and examined the indication for and the audiological outcome following reimplantation. RESULTS: The reimplanted patients showed stable and comparable audiological results for monosyllables and numbers for best fitted situation before and following reimplantation. Technical upgrades did not result in a significant improvement of speech perception. CBCT scans of reimplanted ears did not show significant increased rates of scalar dislocation or partial insertion. CONCLUSION: Even with a technical upgrade, reimplantation does not improve speech perception outcome in CI patients. Therefore, the indication to reimplant should be approved critically. Reimplantation does not lead to a significantly increased risk for partial insertion, scalar dislocation or diminished electrode array insertion angle.

Hearing outcome after tympanoplasty type III.

PURPOSE: We assessed overall hearing outcome after tympanoplasty type III in chronically infected ears with cholesteatoma (CH) and without cholesteatoma: otitis media chronica mesotympanalis, tympanosclerosis, and adhesive process (COM_T_AP). METHODS: 303 surgeries were evaluated: 229 CH-group and 74 COM_T_AP-group. Air-bone gaps (PTA-ABG) with pure-tone averages (PTA-4) at four frequencies (0.5, 1, 2 and 4 kHz) were compared preoperatively, early postoperatively (< 40 days) and late postoperatively (40-400 days). Hearing outcome was compared in various types of middle-ear reconstruction and in smokers and non-smokers. Correlations between hearing outcome and predictive staging indices were evaluated: Middle Ear Risk-Index (MER-I) and Ossiculoplasty Outcome Parameter Staging-Index (OOPS-I). RESULTS: Mean PTA-ABG in the CH-group increased from 20.9 ± 11.3 dB to 22.3 ± 10.4 dB early postoperatively and decreased significantly to 19.2 ± 10.1 dB late postoperatively. Mean PTA-ABG in the COM_T_AP-group decreased significantly from 27.3 ± 10.9 dB to 20.6 ± 10.9 dB early postoperatively and decreased to 20.0 ± 12.2 dB late postoperatively. No significant difference was seen between PTA-ABG-closures of partial or total ossicular replacement prosthesis (PORP/TORP) and cartilage ossiculoplasty in the CH-group. Patients receiving TORP showed a significantly higher preoperative PTA-ABG. All reconstruction types exhibited postoperative PTA-ABG around 20 dB. In the COM_T_AP-group, smokers had a significantly higher mean PTA-ABG early postoperatively; this equalized with that of non-smokers late postoperatively. PTA-ABG-closures and MER-I or OOPS-I were not significantly correlated. CONCLUSION: Tympanoplasty type III maintains hearing in patients with cholesteatoma and significantly improves hearing in chronically inflamed ears without cholesteatoma. All investigated ossicular replacement prostheses are equally beneficial. Healing postoperatively takes longer in smokers, but they eventually catch up with non-smokers.

Deafness after COVID-19?

This article presents a case of sudden bilateral deafness in the context of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection and resultant coronavirus disease 2019 (COVID-19). After treatment in the intensive care unit for acute respiratory distress syndrome and acute kidney failure, hearing ability had drastically changed. While hearing had been subjectively normal before the infection, deafness was now measured on the left and profound hearing loss on the right ear. The patient was treated with cochlea implants on the left and a hearing aid in the right ear. The hearing loss is most likely a complication of COVID-19.

[Deafness after COVID-19? German version]. / Ertaubung nach COVID-19?

This article presents a case of sudden bilateral deafness in the context of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection and resultant coronavirus disease 2019 (COVID-19). After treatment in the intensive care unit for acute respiratory distress syndrome and acute kidney failure, hearing ability had drastically changed. While hearing had been subjectively normal before the infection, deafness was now measured on the left and profound hearing loss on the right ear. The patient was treated with cochlea implants on the left and a hearing aid in the right ear. The hearing loss is most likely a complication of COVID-19.

Navigated, endoscopically controlled, transtympanic resection of an infracochlear cholesteastoma recurrence.

An infracochlear cholesteatoma of the petrous apex with direct contact to the internal carotid artery (ICA) is rare. Due to the risk of cochlear injury with consecutive deafness or injury of the ICA, precise preoperative planning of the approach and strategy is recommended, as well as thorough preoperative counseling of the patient for their informed consent. This case report presents navigated endoscopically controlled transtympanic resection of such a cholesteatoma recurrence. Hearing capacity was not impaired and the patient shows no signs of recurrence.

[Navigated endoscopically controlled transtympanic resection of an infracochlear cholesteatoma recurrence. German version]. / Navigierte endoskopisch-kontrollierte transtympanale Resektion eines infracochleären Cholesteatomrezidivs.

An infracochlear cholesteatoma of the petrous apex with direct contact to the internal carotid artery (ICA) is rare. Due to the risk of cochlear injury with consecutive deafness or injury of the ICA, precise preoperative planning of the approach and strategy is recommended, as well as thorough preoperative counseling of the patient for their informed consent. This case report presents navigated endoscopically controlled transtympanic resection of such a cholesteatoma recurrence. Hearing capacity was not impaired and the patient shows no signs of recurrence.

Speech Recognition in Noise in Single-Sided Deaf Cochlear Implant Children on Using Adaptive Digital Microphone Technology.

BACKGROUND: Previous research demonstrated benefits of adaptive digital microphone technologies (ADMTs) in adults with single-sided deafness (SSD) having a cochlear implant (CI). Children with SSD are especially affected by background noise because of their noise exposure in kindergarten and school. PURPOSE: This article aims to evaluate possible effects of ADMT on speech recognition in background noise in children with SSD who use a CI. STUDY SAMPLE: Ten children between 5 and 11 years of age were included. DATA COLLECTION AND ANALYSIS: Speech recognition in noise was assessed for one frontal distant and two lateral speakers. The speech stimulus was presented at a speech level of 65 dB(A) and noise at a level of 55 dB(A). For the presentation condition with one frontal speaker, four listening conditions were assessed: (1) normal-hearing (NH) ear and CI turned off; (2) NH ear and CI; (3) NH ear and CI with ADMT; and (4) NH ear with ADMT and CI. Listening conditions (2) to (4) were also tested for each lateral speaker. The frontal speaker was positioned directly in front of the participant, whereas the lateral speakers were positioned at angles of 90 degrees and -90 degrees to the participant's head. RESULTS: Children with SSD who use a CI significantly benefit from the application of ADMT in speech recognition in noise for frontal distant and for lateral speakers. Speech recognition improved significantly with ADMT at the CI and the NH ears. CONCLUSION: Application of ADMT significantly improves speech recognition in noise in children with SSD who use a CI and can therefore be highly recommended. The decision of whether to apply ADMT at the CI NH ear or bilaterally should be made for each child individually.

Quality of cochlear implant rehabilitation under COVID-19 conditions.

BACKGROUND: The rehabilitation process following cochlear implant (CI) surgery is carried out in a multimodal therapy according to German national guidelines and includes technical and medical aftercare. In times of the corona pandemic surgery and rehabilitation appointments were cancelled or delayed leading to a more difficult access to auditory rehabilitation. Newly implemented hygiene modalities due to the SARS-CoV­2 pandemic have changed medical aftercare and the rehabilitation process. The aim of this study was to evaluate the quality of rehabilitation under corona conditions. MATERIAL AND METHODS: An anonymous survey of adult cochlear implant patients was carried out by a non-standardized questionnaire. Demographics were analyzed and the quality of medical aftercare, speech therapy, technical aftercare, psychological support and the hygiene modalities were compared to previous rehabilitation stays. RESULTS: In total 109 patients completed the questionnaire. The quality of rehabilitation and individual therapy were rated as qualitatively similar or improved. The threat of the pandemic and fear of corona were rated unexpectedly high with 68% and 50%, respectively. The hygiene measures during the rehabilitation stay eased subjective fears at the same time. The majority of patients were annoyed by wearing face masks but visors, protection shields and social distancing were more tolerated. CONCLUSION: The implementation of the new hygiene modalities within the therapeutic rehabilitation setting was well-accepted by patients allowing access to auditory rehabilitation. A successful rehabilitation should ensure a fear-free environment by adhering to the necessary hygiene modalities.

Radiological evaluation of a new straight electrode array compared to its precursors.

OBJECTIVE: The aim of this study is to examine electrode array coverage, scalar position and dislocation rate in straight electrode arrays with special focus on a new electrode array with 26 mm in lengths. STUDY DESIGN: Retrospective study. SETTING: Tertiary academic center. PATIENTS: 201 ears implanted between 2013 and 2019. MAIN OUTCOME MEASURES: We conducted a comparative analysis of patients implanted with lateral wall electrode arrays of different lengths (F24 = MED-EL Flex24, F26 = MED-EL Flex26, F28 = MED-EL Flex28 and F31.5 = MED-EL FlexSoft). Cone beam computed tomography was used to determine electrode array position (scala tympani (ST) versus scala vestibuli (SV), intracochlear dislocation, position of dislocation and insertion angle). RESULTS: Study groups show no significant differences regarding cochlear size which excludes influences by cochlear morphology. As expected, the F24 showed significant shorter insertion angles compared to the longer electrode arrays. The F26 electrode array showed no signs of dislocation or SV insertion. The electrode array with the highest rate of ST dislocations was the F31.5 (26.3%). The electrode array with the highest rates of SV insertions was the F28 (5.75%). Most of the included electrode arrays dislocate between 320° and 360° (mean: 346.4°; range from 166° to 502°). CONCLUSION: The shorter F24 and the new straight electrode array F26 show less or no signs of scalar dislocation, neither for round window nor for cochleostomy insertion than the longer F28 and the F31.5 array. As expected, the cochlear coverage is increasing with length of the electrode array itself but with growing risk for scalar dislocation and with the highest rates of dislocation for the longest electrode array F31.5. Position of intracochlear dislocation is in the apical cochlear part in the included lateral wall electrode arrays.

[Quality of cochlear implant rehabilitation under COVID-19 conditions. German version]. / Qualität der Cochleaimplantat-Rehabilitation unter COVID-19-Bedingungen.

BACKGROUND: The rehabilitation process following cochlear implant (CI) surgery is carried out in a multimodal therapy according to German national guidelines and includes technical and medical aftercare. In times of the corona pandemic surgery and rehabilitation appointments were cancelled or delayed leading to a more difficult access to auditory rehabilitation. Newly implemented hygiene modalities due to the SARS-CoV­2 pandemic have changed medical aftercare and the rehabilitation process. The aim of this study was to evaluate the quality of rehabilitation under corona conditions. MATERIAL AND METHODS: An anonymous survey of adult cochlear implant patients was carried out by a non-standardized questionnaire. Demographics were analyzed and the quality of medical aftercare, speech therapy, technical aftercare, psychological support and the hygiene modalities were compared to previous rehabilitation stays. RESULTS: In total 109 patients completed the questionnaire. The quality of rehabilitation and individual therapy were rated as qualitatively similar or improved. The threat of the pandemic and fear of corona were rated unexpectedly high with 68% and 50%, respectively. The hygiene measures during the rehabilitation stay eased subjective fears at the same time. The majority of patients were annoyed by wearing face masks but visors, protection shields and social distancing were more tolerated. CONCLUSION: The implementation of the new hygiene modalities within the therapeutic rehabilitation setting was well-accepted by patients allowing access to auditory rehabilitation. A successful rehabilitation should ensure a fear-free environment by adhering to the necessary hygiene modalities.

Incomplete partition type III revisited-long-term results following cochlear implant.

BACKGROUND: Incomplete partition type III (IP III) is defined by a missing lamina cribrosa between the cochlea and the internal auditory canal (IAC). Cochlear implantation (CI) may result in an insertion of the electrode array into the IAC. The aim of this study is to evaluate CI surgery protocols, long-term audiological outcome, mapping and electrophysiological data after CI in IP III patients. MATERIALS AND METHODS: Nine IP III patients were implanted with perimodiolar electrode arrays between 1999 and 2014; eight of them were included in this study. We evaluated mapping data, stapedius reflexes, electrode impedances and ECAP thresholds. We matched them with 3 CI patients each with normal cochlear morphology regarding sex, age, side, implant type and surgical date. Speech discrimination was evaluated with the Oldenburger sentence test for adults, Göttingen audiometric speech test for children and the Freiburger monosyllabic word test. RESULTS: 3 years after CI IP III patients showed a significant increase in pulse width, calculated electric load and electrode impedances in basal electrodes. Intraoperative electrically-evoked stapedius reflexes could be measured in all patients. Speech recognition scores were lower than average scores for matched patients, but without statistical significance. CONCLUSIONS: The significant increase of pulse width, electric load and electrode impedances of basal electrodes over time seem to be characteristic for IP III patients probably occurring due to fibrosis and neurodegeneration of the cochlear nerve. The long term audiological results are stable. Intraoperative imaging and stapedius reflexes are highly recommended to control the right position of the electrode array.

Influence of single-sided deafness on the auditory capacity of the better ear.

BACKGROUND: Patients with single-sided deafness (SSD) are limited by their asymmetric hearing in various areas of everyday life. OBJECTIVE: The aim of this investigation was to perform an age-correlated comparison of the hearing threshold of the better ear of SSD patients with a normal-hearing (NH) reference cohort. In addition, the potential influence of etiology, duration of deafness, and cochlear implantation (CI) of the poorer ear on the peripheral hearing ability of the better ear was investigated. MATERIALS AND METHODS: In a multicenter study, the mean bone conduction hearing threshold of the better ear of 413 adult SSD patients was compared with that of an NH cohort drawn from ISO 7029:2017 for the frequencies 0.5, 1, 2, and 4 kHz. RESULTS: SSD patients showed significantly poorer hearing in the better ear compared to the age-correlated group of NH subjects. CI, duration of deafness, and etiology had no significant effect on the hearing ability of the better ear. CONCLUSION: The origin of the poorer hearing of the better-hearing ear of SSD patients compared to an age-correlated NH cohort is still unclear. It is most likely a combination of different anatomical, immunological, etiological, and microcirculatory causes, which lead to poorer hearing of the better-hearing ear in SSD patients.

[Dichotic speech recognition with cochlear implants]. / Dichotisches Sprachverstehen mit Cochleaimplantaten.

BACKGROUND: Dichotic speech recognition of side-separated speech stimuli requires their central nervous processing and has been used since the 1950s in a variety of clinical settings. OBJECTIVE: The objective of this study was to investigate the dichotic speech recognition of normal-hearing (NH) subjects, cochlear implant (CI) recipients with single-sided deafness (SSD), and bilateral CI (BilCI) recipients with the dichotic discrimination test according to Feldmann. MATERIALS AND METHODS: The speech recognition of ten adult NH subjects, ten SSD CI recipients, and ten BilCI recipients was determined at 65 dB SPL or 65 dB SPL equivalent for monotic presentation of trisyllabic nouns of the Feldmann test (NH subjects: better ear, poorer ear; SSD CI recipients: NH ear, CI; BilCI recipients: better CI, poorer CI) and for dichotic, i.e., simultaneous side-separated, presentation. RESULTS: The NH subjects showed significantly poorer speech recognition for dichotic presentation than for monotic presentation. Speech recognition of SSD CI recipients was significantly worse with the CI than with the NH ear for both monotic and dichotic presentation. For both presentation conditions, BilCI recipients obtained significantly lower speech recognition with the poorer CI compared to the better CI. With each of the two CI, BilCI recipients had significantly worse speech recognition for dichotic presentation than for monotic presentation. CONCLUSION: All three study groups-NH subjects, SSD CI recipients, and BilCI recipients-were able to recognize dichotically presented speech with both ears. For SSD CI recipients, there was no negative effect of the CI on speech recognition with the NH ear for dichotic presentation.

[Incomplete partition type III revisited-long-term results following cochlear implant. German version]. / "Incomplete partition type III" ­ Langzeitergebnisse nach Cochleaimplantation.

BACKGROUND: Incomplete partition type III (IP III) is defined by a missing lamina cribrosa between the cochlea and the internal auditory canal (IAC). Cochlear implantation (CI) may result in an insertion of the electrode array into the IAC. The aim of this study is to evaluate CI surgery protocols, long-term audiological outcome, mapping and electrophysiological data after CI in IP III patients. MATERIALS AND METHODS: Nine IP III patients were implanted with perimodiolar electrode arrays between 1999 and 2014; eight of them were included in this study. We evaluated mapping data, stapedius reflexes, electrode impedances and ECAP thresholds. We matched them with 3 CI patients each with normal cochlear morphology regarding sex, age, side, implant type and surgical date. Speech discrimination was evaluated with the Oldenburger sentence test for adults, Göttingen audiometric speech test for children and the Freiburger monosyllabic word test. RESULTS: 3 years after CI IP III patients showed a significant increase in pulse width, calculated electric load and electrode impedances in basal electrodes. Intraoperative electrically-evoked stapedius reflexes could be measured in all patients. Speech recognition scores were lower than average scores for matched patients, but without statistical significance. CONCLUSIONS: The significant increase of pulse width, electric load and electrode impedances of basal electrodes over time seem to be characteristic for IP III patients probably occurring due to fibrosis and neurodegeneration of the cochlear nerve. The long term audiological results are stable. Intraoperative imaging and stapedius reflexes are highly recommended to control the right position of the electrode array.

[Influence of single-sided deafness on the auditory capacity of the better ear. German version]. / Einfluss einseitiger Taubheit auf das Hörvermögen des besseren Ohrs.

BACKGROUND: Patients with single-sided deafness (SSD) are limited by their asymmetric hearing in various areas of everyday life. OBJECTIVE: The aim of this investigation was to perform an age-correlated comparison of the hearing threshold of the better ear of SSD patients with a normal-hearing (NH) reference cohort. In addition, the potential influence of etiology, duration of deafness, and cochlear implantation (CI) of the poorer ear on the peripheral hearing ability of the better ear was investigated. MATERIALS AND METHODS: In a multicenter study, the mean bone conduction hearing threshold of the better ear of 413 adult SSD patients was compared with that of an NH cohort drawn from ISO 7029:2017 for the frequencies 0.5, 1, 2, and 4 kHz. RESULTS: SSD patients showed significantly poorer hearing in the better ear compared to the age-correlated group of NH subjects. CI, duration of deafness, and etiology had no significant effect on the hearing ability of the better ear. CONCLUSION: The origin of the poorer hearing of the better-hearing ear of SSD patients compared to an age-correlated NH cohort is still unclear. It is most likely a combination of different anatomical, immunological, etiological, and microcirculatory causes, which lead to poorer hearing of the better-hearing ear in SSD patients.