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.

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. 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.

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.

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.

[Functional outcomes after surgical treatment of oropharyngeal carcinomas]. / Funktionelle Ergebnisse nach chirurgischer Therapie von Oropharynxkarzinomen.

INTRODUCTION: The primary goal of surgical resection of oropharyngeal carcinoma (OPSCC) is an R0 resection. The extension of the primary tumor is decisive for selection of access route, which should be as circumscribed as possible but as radical as necessary. To date, there are no prospective comparative studies that compared functional outcome in terms of surgical access route. MATERIALS AND METHODS: A selective literature search was carried out for the period from 01/01/2000 to 12/31/2019 to assess the functional result after different surgical approaches in the treatment of OPSCC. The search strategy aimed to identify publications that investigated the functional result of transoral approaches, robot-assisted transoral resections (TORS), and surgical resection using pharyngotomies or transmandibular approaches. RESULTS: Various measures were identified which enable subjective and objective assessment of swallowing and speaking restrictions. For all surgical access routes, studies were identified that examined the functional aspects of the respective access, but there are no direct comparisons between the individual approaches. CONCLUSION: There are various surgical approaches available for resection of OPSCC, each of which has been examined in various studies with regard to its oncological and functional results.

[Objective and subjective assessment of a structured approach to computed tomography scans of the paranasal sinuses]. / Objektive und subjektive Bewertung eines strukturierten Vorgehens zur Beurteilung von Computertomographien der Nasennebenhöhlen.

BACKGROUND: Sound knowledge of individual anatomy is essential in sinus surgery to prevent potentially serious complications. For the paranasal sinuses, computed tomography (CT) is the imaging technique of choice to preoperatively analyze individual anatomy and the extent of disease. OBJECTIVE: The purpose of this study was to evaluate the usefulness of a CT checklist to identify relevant anatomic variants in CTs of the paranasal sinuses. MATERIALS AND METHODS: Junior and senior otolaryngology residents were asked to assess sinus CT scans for anatomic variants before and after implementation of the CLOSE mnemonic (cribriform plate, lamina papyracea, Onodi cell, sphenoid sinus pneumatization, and [anterior] ethmoidal artery). The rate of correctly identified variants was calculated. A questionnaire was distributed for subjective evaluation of the usefulness of the checklist. RESULTS: Six junior and six senior residents were included in the study. The rate of correctly identified anatomic variations significantly improved from 23.1 to 50.9% and 24 to 39.8%, respectively, after implementation of the CLOSE mnemonic. The subjective evaluation of the CLOSE criteria showed very positive results. CONCLUSION: The structured approach to sinus CT scans using CT criteria can improve identification of critical anatomic variants in CT scans of the paranasal sinuses and is rated highly positively by residents in training.

[The 8th edition of the TNM staging system-a curse or a blessing for oropharyngeal carcinoma?] / Die 8. Version der TNM-Klassifikation ­ Fluch oder Segen für das Oropharynxkarzinom?

At the beginning of 2017, the 8th edition of the TNM classification was presented. For oropharyngeal carcinoma, this was accompanied by a paradigm shift, as a separation of the classification depending on the association with human papillomavirus (HPV) status has been established. By considering the literature, this paper provides an overview of the characteristics of HPV-associated carcinomas, the new features of the TNM classification, and the existing points of discussion. The revision has improved the prognostic significance of the TNM classification; however, there are still tumor- and patient-dependent influencing factors that must be considered for future versions.

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.

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.

Surgical nodal management in hypopharyngeal and laryngeal cancer.

OBJECTIVE: The aim of this study is to compare pre-therapeutic staging of the loco-regional lymphatic basin and subsequent surgical management in cN0 versus cN+ hypopharyngeal and laryngeal cancer patients. METHODS: We analyzed all hypopharyngeal and laryngeal carcinoma patients treated surgically at a single quaternary medical care and cancer center between 2004 and 2014. We established two groups for patients who underwent neck dissection comparing patients with a low LNR (lymph node ratio) to one with a high LNR. Regarding the cN0 cohort, elective neck dissection was evaluated as a secondary predictor variable. Comorbidities, such as anemia and renal insufficiency, were analyzed as potentially influencing disease-free (DFS) and overall survival (OS). RESULTS: A total of 310 patients (185 glottic and 125 supraglottic/hypopharyngeal carcinoma) were included. Pre-therapeutic neck MRI-/CT-scan and concomitant neck ultrasound revealed cN+ status in 144 patients resulting in a significant over-staging in 63 patients (44%) who were rated as being pN0 after histological examination. 166 patients were staged cN0 and 21 underwent elective neck dissection (11 local advanced glottic and 10 supraglottic/hypopharyngeal carcinoma). Two cN0 patients showed occult cervical lymph node metastases (10%). Furthermore, we could detect a significant negative impact of the LNR divided by the number of dissected lymph nodes and OS. CONCLUSION: The pre-therapeutic clinical evaluation of lymphatic outgrowth is over-staged. OS decreases with increasing LNR divided by the number of dissected lymph nodes. Renal insufficiency and anemia are significant negative factors, decreasing both OS and DFS.

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.

Improvement in tinnitus distress, health-related quality of life and psychological comorbidities by cochlear implantation in single-sided deaf patients.

BACKGROUND: Patients with single-sided deafness (SSD) lack the ability localize sound sources and have difficulty with speech-in-noise hearing. In addition, there is a high prevalence of tinnitus distress. These problems may result in reduced health-related quality of life (HRQoL) and psychological comorbidities. This study aimed to investigate the influence of treatment with a cochlear implant (CI) on HRQoL, tinnitus distress, psychological comorbidities, and audiological parameters in SSD patients. METHODS: This retrospective study included 20 patients with postlingually acquired SSD (13 women, 7 men, mean age 57.0 years). Data on HRQoL were collected with the Nijmegen Cochlear Implant Questionnaire (NCIQ) and the Medical Outcome Study Short Form 36 Survey (SF-36). Tinnitus distress was assessed with the Tinnitus Questionnaire (TQ), psychological comorbidities were evaluated with validated questionnaires, and speech perception and hearing ability were measured with validated speech tests. RESULTS: Postoperatively, the mean total NCIQ score (p < 0.0001) and four subscores improved significantly, as did tinnitus distress (p < 0.05). Anxiety symptoms (Generalized Anxiety Disorder questionnaire, GAD-7) decreased significantly after CI. Speech perception improved significantly, particularly "hearing with background noise" (p < 0.05, Oldenburg Inventory, OI) and "localization" (p < 0.001, OI), as well as the Oldenburg Sentence Test (OlSa) scores for with vs. without CI when speech was presented from the SSD side and noise was presented from the normal hearing side (SSSDNNH; p < 0.005). CONCLUSION: CI in SSD patients is a powerful procedure to improve HRQoL, reduce tinnitus distress, and improve psychological comorbidities. Additionally, it is beneficial for hearing improvement, particularly in noise and for directional hearing.

[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.

[Improvement in tinnitus distress, health-related quality of life and psychological comorbidities by cochlear implantation in single-sided deaf patients. German version]. / Verbesserung von Tinnitusdistress, Lebensqualität und psychologischen Komorbiditäten durch Cochleaimplantation einseitig ertaubter Patienten.

BACKGROUND: Patients with single-sided deafness (SSD) lack the ability localize sound sources and have difficulty with speech-in-noise hearing. In addition, there is a high prevalence of tinnitus distress. These problems may result in reduced health-related quality of life (HRQoL) and psychological comorbidities. This study aimed to investigate the influence of treatment with a cochlear implant (CI) on HRQoL, tinnitus distress, psychological comorbidities, and audiological parameters in SSD patients. METHODS: This retrospective study included 20 patients with postlingually acquired SSD (13 women, 7 men, mean age 57.0 years). Data on HRQoL were collected with the Nijmegen Cochlear Implant Questionnaire (NCIQ) and the Medical Outcome Study Short Form 36 Survey (SF-36). Tinnitus distress was assessed with the Tinnitus Questionnaire (TQ), psychological comorbidities were evaluated with validated questionnaires, and speech perception and hearing ability were measured with validated speech tests. RESULTS: Postoperatively, the mean total NCIQ score (p < 0.0001) and four subscores improved significantly, as did tinnitus distress (p < 0.05). Anxiety symptoms (Generalized Anxiety Disorder questionnaire, GAD-7) decreased significantly after CI. Speech perception improved significantly, particularly "hearing with background noise" (p < 0.05, Oldenburg Inventory, OI) and "localization" (p < 0.001, OI), as well as the Oldenburg Sentence Test (OlSa) scores for with vs. without CI when speech was presented from the SSD side and noise was presented from the normal hearing side (SSSDNNH; p < 0.005). CONCLUSION: CI in SSD patients is a powerful procedure to improve HRQoL, reduce tinnitus distress, and improve psychological comorbidities. Additionally, it is beneficial for hearing improvement, particularly in noise and for directional hearing.

[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.

[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.

The influence of cochlear morphology on the final electrode array position.

OBJECTIVE: Preoperative information about cochlear morphology and size increasingly seems to be a defining factor of electrode choice in cochlear implant surgery. Different types of electrodes differ in length and diameter to accommodate individual cochlear anatomy. Smaller cochlear size results in increased insertion depth with a higher risk to dislocate and causes cochlear trauma with reduced postoperative outcome. The objective of the current study is to describe the three-dimensional size of the cochlea, to compare interindividual differences, to determine the relationship between cochlear size and insertion angle, and to define risk factors for dislocation during insertion. DESIGN: Four hundred and three patients implanted between 2003 and 2010 inserted via cochleostomy with a perimodiolar electrode array (Cochlear™ Contour Advance® electrode array) have been compared. CBCT (Cone beam computed tomography) was used to determine electrode array position (scala tympani versus scala vestibuli insertion, intracochlear dislocation, and insertion angle) and cochlear size (diameters and height). The trajectory of the electrode array and the lateral wall have been measured, and the position of the electrode array has been estimated. RESULTS: The mean value of the largest diameter was 9.95 mm and that of the perpendicular distance was 6.54 mm. There was a statistically significant correlation between those values. Mean height was 3.85 mm. The intracochlear relation of the electrode array and the modiolus showed a statistically significant relationship with the cochlear expanse. The electrode array was more likely to dislocate in cochleae with a smaller diameter and a lower height. Cochleae with insertions into scala vestibuli exhibited a smaller height compared to scala tympani insertions with statistical significance. CONCLUSION: Cochlear size and shape is variable, and the measured data of this study confirm the finding of other researchers. This study established two heights by two different planes to achieve a three-dimensional understanding of the cochlea. The electrode array was more likely to dislocate in cochleae with smaller diameter and smaller height. It can be assumed that the height established in this study seems to be a new preoperative parameter to underline the risk of scalar dislocation and not favored scala vestibuli insertion if using a cochleostomy approach. In conclusion, cochlear size, especially the height, is influencing the final position of the electrode array. Using preoperative scans of the cochlear diameters and cochlear height, a next step to custom-sized arrays is available.