Implications of intracochlear decomposition gas formation in non-putrefied cadavers.

Introduction: Postmortem computed tomography (pmCT) prior to forensic autopsy has become increasingly important in recent decades, especially in forensic documentation of single injuries, injury patterns, and causes of death. Postmortem decomposition gas formation can also be detected in pmCT scans, which might affect cochlear implant research in postmortem human temporal bones (TBs). Material and methods: Fifty non-putrefied hanging fatalities within a 2-year period (January 2017 to December 2019) were included with 100 TBs. Each body underwent whole-body pmCT prior to forensic autopsy. PmCT scans were analyzed with respect to the presence of intracochlear gas despite the lack of putrefaction at autopsy by an experienced fellow neurotologist. Results: PmCT revealed gas formation in two individuals despite the lack of head trauma and putrefaction at postmortem examination and autopsy. Both individuals showed enclosed gas in the vestibule and the cochlea on both sides. Discussion: Intracochlear gas formation, most likely related to decomposition, may occur despite the lack of putrefaction at postmortem examination and autopsy and can be detected by pmCT. This finding seems to be rather rare in non-traumatic death cases but might affect cochlear pressure research in postmortem human TB.

Preservation of Residual Hearing: Long-Term Results With a Mid-Scala Electrode.

OBJECTIVE: The long-term preservation of residual hearing after cochlear implantation has become a major goal over the past few years. The aim of the present study was to evaluate residual hearing in the long-term follow-up using mid-scala electrodes. METHODS: In this retrospective, single-center study, we collected data from 27 patients who were implanted between 2014 and 2015 with residual hearing in the low-frequency range using a mid-scala electrode. Measurements of the hearing thresholds were carried out directly postoperatively (day 1 after surgery) and in the long-term follow-up 43.7 ± 6.9 months. The calculation of the extent of audiological hearing preservation was determined using the HEARRING group formula by Skarsynski. RESULTS: Postoperative preservation of residual hearing was achieved in 69.2% of the cases in the low-frequency range between 250 Hz and 1 kHz, of which 89.5% of the patients had frequencies that suggested using electroacoustic stimulation (EAS). In the long-term follow-up, 30.8% of the patients showed residual hearing; however, 57.1% had apparently benefited from EAS. CONCLUSION: Preservation of residual hearing is feasible in the long term using mid-scala electrodes. Postoperatively, there is over the half of patients who benefit from an EAS strategy. The long-term follow-up shows a certain decrease in residual hearing. However, these results are comparable to studies relating to other types of electrodes. Further research should be conducted in future to better evaluate hearing loss in long-term follow-up, compared to direct postoperative audiological results.

Triple Semi-Circular Canal Occlusion and Cochlear Implantation: A Treatment Option for Single-Sided Menière's Disease with Functional Deafness-A Case Series.

The surgical options for patients with single-sided Menière's disease and functional deafness are challenging. Our case series reports the outcomes of surgical treatments of patients with single-sided Menière's disease and functional deafness. These patients have undergone a one-staged occlusion of all semi-circular canals and cochlear implantation. Five patients (four female and one male; 62 ± 8.2 years with a range from 50 to 72 years) with single-sided Menière's disease and functional deafness were included in this study. In all cases, the patients suffered from frequent rotational vertigo episodes for many years. Other treatment options (e.g., medication) had not yet been successful. Preoperatively, the Dizziness Handicap Inventory (DHI) of all patients indicated severe emotional, physical, and functional deficits. Patients showed a functional (near-total) deafness of the affected ear in all cases. All patients were supplied with cochlear implants in combination with a triple occlusion of all semi-circular canals in a one-stage procedure. After a short period of increased dizziness following surgery and after the activation of the cochlear implant and CI rehabilitation (auditory-verbal therapy), vertigo control and an adequate audiological outcome were achieved. The DHI showed a constant decrease after surgery. The combination of a triple semi-circular canal occlusion and cochlear implantation can be an efficient treatment for patients with single-sided Menière's disease.

Long-Term, Multicenter Results With the First Transcutaneous Bone Conduction Implant.

OBJECTIVE: Investigation of long-term safety and performance of an active, transcutaneous bone conduction implant in adults and children up to 36 months post-implantation. STUDY DESIGN: Prospective, single-subject repeated-measures design. SETTING: Otolaryngology departments of eight German and Austrian hospitals.∗†‡§||¶#∗∗†† Affiliations listed above that did not participate in the study.‡‡§§||||¶¶. PATIENTS: Fifty seven German-speaking patients (49 adults and eight children) suffering from conductive or mixed hearing loss, with an upper bone conduction threshold limit of 45 dB HL at frequencies between 500 and 3000 Hz. INTERVENTION: Implantation of the Bonebridge transcutaneous bone conduction hearing implant (tBCI). MAIN OUTCOME MEASURES: Patients' audiometric pure tone averages (PTA4) (0.5, 1, 2, 4 kHz) thresholds (air conduction, bone conduction, and sound field) and speech perception (word recognition scores [WRS] and speech reception thresholds [SRT50%]) were tested preoperatively and up to 36 months postoperatively. Patients were also monitored for adverse events and administered quality-of-life questionnaires. RESULTS: Speech perception (WRS: pre-op: 17.60%, initial activation [IA]: 74.23%, 3M: 83.65%, 12M: 83.46%, 24M: 84.23%, 36M: 84.42%; SRT50%: pre-op: 65.56 dB SPL, IA: 47.67 dB SPL, 3M: 42.61 dB SPL, 12M: 41.11 dB SPL, 24M: 41.74 dB SPL, 36M: 42.43 dB SPL) and sound field thresholds (pre-op: 57.66 dB HL, IA: 33.82 dB HL, 3M: 29.86 dB HL, 12M: 28.40 dB HL, 24M: 28.22 dB HL, 36M: 28.52 dB HL) improved significantly at all aided postoperative visits. Air and bone conduction thresholds showed no significant changes, confirming preservation of patients' residual unaided hearing. All adverse events were resolved by the end of the study. CONCLUSIONS: Safety and performance of the tBCI was demonstrated in children and adults 36 months postoperatively.

Minimizing Intracochlear Pressure: Influence of the Insertion Sheath.

OBJECTIVE: Atraumatic cochlear implantation (CI) and insertion of the electrode in particular are major goals of recent CI surgery. Perimodiolar electrode arrays need a stylet or exosheath for insertion. The sheath can influence the intracochlear pressure changes during insertion of the electrode. The aim of this study was to modify the insertion sheath to optimize intracochlear pressure changes. METHODS: In an artifical cochlear model, 7 different modified insertion sheaths were used. The intracochlear pressure was measured with a micro-optical sensor in the apical part of the model cochlea. RESULTS: Significant lower intracochlear pressure changes were observed when the apical part of the insertion sheath was either shortened or tapered. Modification of the stopper does influence the intracochlear pressure significantly. CONCLUSION: Modification of the insertion sheath leads to lower intracochlear pressure gain. The differences and impact on intracochlear pressure changes found in this study underline the importance of even subtle modifications of the electrode insertion technique.

Can hearing amplification improve presbyvestibulopathy and/or the risk-to-fall ?

PURPOSE: The decline of sensory systems during aging has been widely investigated and several papers have correlated the visual, hearing and vestibular systems and the consequences of their functional degeneration. Hearing loss and presbyvestibulopathy have been found to be positively correlated as is with the risk-to-fall. MATERIAL AND METHODS: The present study was therefore designed as systematic review (due to PRISMA criteria) which should correlate hearing amplification by hearing aids and/or cochlear implants with balance outcome. However, the literature review (Cochrane, PubMed) revealed ten paper (prospective, controlled trials and acute trials) with heterogenous patient popiulations and non-uniform outcome measures (i.e., gait analysis, questionnaires, postural stabilometry) so that no quantitative, statistical analysis could be performed. RESULTS: The qualitative analysis oft he identified studies showed that hearing amplification in the elderly improves spatio-temporal orientation (particularly with cochlear implants) and that the process of utilizing auditory information for balance control takes some time (i.e., the neuroplasticity-based, learning processes), usually some months in cochlear implantees. DISCUSSION: Hearing and balance function degenerate independently from each other and large interindividual differences require a separate neurotological examination of each patient. However, hearing amplification is most helpful to improve postural stability, particularly in the elderly. Future research should focus on controlled, prospective clinical trials where a standardized test battery covering the audiological and neurotological profile of each elderly patient pre/post prescription of hearing aids and/or cochlear implantation should be followed up (for at least 1 year) so that also the balance improvements and the risk-to-fall can be reliably assessed (e.g., by mobile posturography and standardized questionnaires, e.g., the DHI).

Intracochlear Pressure Changes After Cochlea Implant Electrode Pullback-Reduction of Intracochlear Trauma.

OBJECTIVE: Different aspects should be considered to achieve an atraumatic insertion of cochlear implant electrode arrays as an important surgical goal. Intracochlear pressure changes are known to influence the preservation of residual hearing. By using the intraoperative "pullback technique," an electrode position closer to the modiolus can be achieved than without the pullback. The aim of the present study was therefore to investigate to what extent the pullback technique can influence intracochlear pressure changes. METHODS: Insertions of cochlear implant electrodes were performed in an artificial cochlear model with two different perimodiolar arrays. Intracochlear pressure changes were recorded with a micro-optical pressure sensor positioned in the apical part of the cochlear. After complete insertion of the electrode array, a so-called pullback of the electrode was performed. RESULTS: Statistically significant pressure differences were measured if the electrode array was wet (ie, moisturized) during the pullback. Relative pressure changes in electrodes with smaller total volume are lower than pressure changes in larger electrodes. CONCLUSION: The preservation of residual hearing and, thus, the resulting postoperative audiological outcome has a major impact on the quality of life of the patients and has become of utmost importance. Intracochlear pressure changes during the pullback manoeuver are small in absolute terms, but can even be still reduced statistically significantly by a moistening the electrode before insertion. Using the pullback technique in cases with residual hearing does not affect the probability of preservation of residual hearing but could lead to a better audiological outcome. LEVEL OF EVIDENCE: NA.

Stapes piston insertion depth and clinical correlations.

Background: The insertion of the stapes piston within the vestibule provides the physical basis for a successful stapedotomy. An insertion depth of 0.5 mm is recommended to avoid the dislocation of the stapes prosthesis (e.g. sneezing). Aims: The objective of this study is to analyze the depth of stapes prosthesis insertion and its correlation with clinical outcome. Material and methods: We observed in a retrospective case series 39 otosclerosis patients after a stapedotomy and a postoperative performed flat panel tomography/cone beam CT. The evaluation included the radiologically found depth of prosthesis insertion within the vestibule, the vestibule depth, and the correlation with the bone conduction (BC) threshold, vertigo, and tinnitus. Results: Insertion depth varied between 0.2 and 1.6 mm (mean 0.74 mm). The ratio of insertion depth versus the vestibule depth was between 8% and 59% (mean 26.6%). We observed no correlation between the insertion depth, the length of the prosthesis, the ratio of insertion depth/vestibule depth, postoperative BC, appearance of vertigo, or tinnitus. Conclusions and significance: In our group, we observed no significant relation between insertion depth of the stapes piston, postoperative vertigo, tinnitus, or decrease of the BC.

Magnetic Resonance Imaging Artifacts and Cochlear Implant Positioning at 1.5 T In Vivo.

OBJECTIVE: Cerebral magnetic resonance imaging with the magnet of the cochlear implant receiver/stimulator in place causes artifacts and hinders evaluation of intracerebral structures. The aim of this study was to evaluate the internal auditory canal and the labyrinth in a 1.5T MRI with the magnet in place. STUDY DESIGN: Observational study. SETTING: Tertiary referral center. SUBJECTS AND METHODS: The receiver/stimulator unit was placed and fixed onto the head of three volunteers at three different angles to the nasion-outer ear canal (90°-160°) and at three different distances from the outer ear canal (5-9 cm). T1 and T2 weighted sequences were conducted for each position. RESULTS: Excellent visibility of the internal auditory canal and the labyrinth was seen in the T2 weighted sequences with 9 cm between the magnet and the outer ear canal at every nasion-outer ear canal angle. T1 sequences showed poorer visibility of the internal auditory canal and the labyrinth. CONCLUSION: Aftercare and visibility of intracerebral structures after cochlear implantation is becoming more important as cochlear implant indications are widened worldwide. With a distance of at least 9 cm from the outer ear canal the artifact induced by the magnet allows evaluation of the labyrinth and the internal auditory canal.

The development of active middle ear implants: A historical perspective and clinical outcomes.

OBJECTIVE S: Energy emitting, active middle ear implants (aMEI) have taken more than two decades of research to reach technological sophistication, medical safety, and regulatory approval to become a powerful tool in treating sensorineural, conductive, and mixed hearing loss. The present review covers this era. DATA SOURCE: Literature found from searching Pubmed (MEDLINE); EMBASE, SciSearch, German Medical Science Journals and Meetings, and The Cochrane Library; and published as of February 2017. Study bibliographies were hand-searched to find further materials. METHODS: A systematic literature review was conducted to identify studies evaluating the safety, efficacy, effectiveness, and subjective outcomes of partially implantable aMEIs. Data were extracted on systems with regulatory approval and summarized narratively. Meta-analyses were conducted for aMEIs with more than 25 publications. Study selection, data extraction, and quality appraisal for quantitative data synthesis was carried out by two reviewers. RESULTS: Four hundred thirty-one studies included in narrative synthesis describe that albeit good audiological outcomes, clinical safety and (dis)investment are major barriers to continued market access. The synthesised risk of adverse events was three fold with the MET than with the VIBRANT SOUNDBRIDGE. With the latter system, audiological outcomes were stable and similar for all indications and age groups. CONCLUSION: To date, the majority of the literature covers the clinical application of the VIBRANT SOUNDBRIDGE system as it is applicable to a wide range of otologic and audiological conditions, particularly with the introduction of couplers to extend its clinical reach. The MAXUM and MET still have to find their way into surgical routine.Level of Evidence.

Hearing Outcomes after Transmastoid Plugging of Superior Canal Dehiscence.

BACKGROUND: Patients with a superior canal dehiscence syndrome display symptoms of the vestibular disorder except that of hearing loss. Therefore, any type of surgery should treat those symptoms without affecting the hearing threshold. The aim of this study was to evaluate the extent to which the hearing threshold has been affected; the evaluation process was carried out by a transmastoid plugging of the superior canal. Another aim was to estimate the risk in loss of hearing due to this surgery. MATERIAL AND METHODS: In a retrospective study, 31 patients with dehiscence of the superior canal, who underwent a transmastoid plugging, were included. Additionally, 8 of them with the clinical symptoms of the Menière's disease received an endolymphatic sac surgery. A b-c threshold at 0.25, 0.5, 1, 2, and 4 kHz was observed in all patients pre and postoperatively as well as in the long-term follow-up. RESULTS: After a mean interval of 149 days, a change in the b-c threshold of 5.9 dB was detected. After 149 days, in the patient group comprising those who underwent an additional endolymphatic sac surgery, a b-c threshold change of 17.18 dB was detected. CONCLUSION: The transmastoid plugging of the superior semicircular canal can be performed with an acceptable risk of hearing affection. If the surgery was combined with other techniques, (e.g. endolymphatic sac surgery) then the risk increases.

In Vivo Measurement of Middle Ear Pressure Changes during Balloon Eustachian Tuboplasty.

BACKGROUND: Balloon Eustachian tuboplasty (BET) is known as a treatment for chronic obstructive Eustachian tube dysfunction (OETD). The precise mechanism of action is not fully understood. Observations in sheep cadavers and human cadavers have shown specific middle ear pressure changes related to BET. METHODS: In this prospective study using a microfibre optical pressure sensor, pressure changes during BET were for the first time monitored transtympanically in five normal human middle ears in vivo. RESULTS: Middle ear pressure changes during 21 BETs consisted of five stages (insertion, inflation, deflation, withdrawal, and recovery). The highest pressure change occurred in most of the cases during the withdrawal of the balloon catheter. Withdrawal pressure yielded a mean middle ear pressure of 4.76 mmHg (61.89 daPa) with a maximum of 13.88 mmHg (179.55 daPa). Pressure amplitudes capable of causing barotrauma to ear structures were not detected. Internal carotid artery dehiscences were detected as causative of sinusidual pressure changes. CONCLUSION: The middle ear pressure changes detected in vivo during BET can be attributed to the balloon inflation. Further human studies with patients affected by OETD are necessary to gain more insight into the mechanism of action of BET to clarify a possible pressure related second mechanism of action of BET.

Cochlear implants and 1.5 T MRI scans: the effect of diametrically bipolar magnets and screw fixation on pain.

BACKGROUND: The probability that a patient will need an MRI scan at least once in a lifetime is high. However, MRI scanning in cochlear implantees is associated with side effects. Moreover, MRI scan-related artifacts, dislodging magnets, and pain are often the most frequent complications. The aim of this study was to evaluate the occurrence of pain in patients with cochlear implant systems using 1.5T MRI scans. METHODS: In a prospective case study of 10 implantees, an MRI scan was performed and the degree of pain was evaluated by a visual analog scale. Scans were performed firstly with and depending on the degree of discomfort/pain, without a headband. Four of the cochlear implants contained a screw fixation. Six cochlear implants contained an internal diametrically bipolar magnet. MRI observations were performed with a 1.5 T scanner. RESULTS: MRI scans were performed on all patients without causing any degree of pain, even without the use of a headband. CONCLUSION: Patients undergoing 1.5 T MRIs with devices including a diametrically bipolar magnet or a rigid implant screw fixation, experienced no pain, even without headbands.

Superior Canal Dehiscence: A Comparative Postmortem Multislice Computed Tomography Study.

OBJECTIVE: Superior canal dehiscence is defined by missing bony coverage of the superior canal against the middle cranial fossa. The gold standard in diagnosis is high-resolution computed tomography (CT). A false-positive CT scan, identifying a dehiscence when one is not present, could lead to unnecessary surgical therapy. This study aims to compare postmortem CT scans with autopsy findings with regard to superior canal dehiscence. STUDY DESIGN: Postmortem study. SETTING: Tertiary referral center. SUBJECTS AND METHODS: Twenty-two nontraumatic death cases within a 3-month period (January to March 2017) were included with 44 temporal bones. Each body underwent postmortem head CT prior to medicolegal autopsy. The middle fossa floor was exposed, and if present, the superior semicircular canal dehiscence was identified and measured. In each case, 3 comparable photographs were taken during the autopsy (left temporal bone, right temporal bone, overview). RESULTS: Autopsy findings revealed bony dehiscences in 11% of the temporal bones, whereas CT scan revealed bony dehiscences in 16%. The length of the dehiscences were longer when measured by CT imaging. CONCLUSION: The diagnosis of superior canal dehiscence syndrome requires high-resolution CT with clinical symptoms and physiologic evidence of a third mobile window. Our study underlines a mismatch between multislice CT imaging in the coronal plane and the presence of a dehiscence on autopsy.

Evaluation of Cochlear Implant Receiver Position and Its Temporal Changes.

HYPOTHESIS: It was the aim of this study to establish normative data regarding intended changes in cochlear implants (CI) receiver positioning by one surgeon over time. BACKGROUND: With the increasing number of CI patients, the probability of needing magnetic resonance imaging (MRI) increases. The accessibility of cerebral structures is limited by MRI artifacts caused by CI. New studies show a dependence of the visibility of intracranial structures by the MRI sequences and the position of the CI receiver itself. METHODS: Retrospective and interindividual investigation of topograms with regard to the nasion-external auditory canal-internal magnet angle and the distance between the internal magnet and the external auditory canal. We evaluated scans of 150 CI recipients implanted from 2008 until 2015. RESULTS: The most common implant position in the years 2008 to 2015 was a nasion-external auditory canal-internal magnet angle between 121 and 140 degrees (mean, 127 degrees) and an internal magnet-external auditory canal distance between 61 and 80 mm (mean, 70 mm). Over time the nasion-external auditory canal-internal magnet angle increased and the internal magnet-external auditory canal distance decreased, both to a statistically significant degree. A difference between the manufacturers was not observed. CONCLUSION: The CI receiver position is important for an artifact-free examination of the internal auditory canal and the cochlea. The realization of the position over a time course supports awareness of artifact-related visibility limitations.

Pain Free 3 T MRI Scans in Cochlear Implantees.

OBJECTIVE: For cochlear implant recipients, undergoing magnetic resonance imaging (MRI) scans is associated with safety risks and potential side effects. Even following safety guidelines, potential complications (e.g., pain, magnet dislocation, image artifacts) are possible during 1.5 Tesla (T) MRI scans. The stronger static magnetic field of a 3.0 T scanner is associated with further risks of complication, including implant demagnetization. These complications led to the recent development of rotatable internal receiver magnets with a diametrical magnetization.The aim of this study was to evaluate the potential occurrence of pain during 3.0 T MRI scans for cochlear implant recipients with a rotatable, diametrically magnetized implant magnet. PATIENTS: Five patients implanted with a cochlear implant diametrically magnetized magnet. INTERVENTION: MRI scanning at 3 T. MAIN OUTCOME MEASURE: In the prospective patient study an MRI scan was performed on five implantees and the degree of pain was evaluated by a visual analog scale. Scans were performed initially with a magnet-supporting headband, and depending on the degree of discomfort/pain, repeated without the headband. RESULTS: In all the patients, all the MRI scans were performed without any pain, even without the use of the supportive headband. Demagnetization was clinically not observed. CONCLUSION: 3.0 T MRI scanning can be performed on cochlear implant recipients with a rotatable diametrically magnetized internal magnet without risk of the most frequent cochlear-implant-related MRI complication: pain. This finding enables the expansion of MRI scanning indications up to 3.0 T without complication. Limitations in terms of MRI artifact still persist.

Cochlear implant electrode sealing techniques and related intracochlear pressure changes.

BACKGROUND: The inserted cochlear implanted electrode is covered at the site of the round window or cochleostomy to prevent infections and leakage. In a surgically hearing preservational concept, low intracochlear pressure changes are of high importance. The aim of this study was to observe intracochlear pressure changes due to different sealing techniques in a cochlear model. METHODS: Cochlear implant electrode insertions were performed in an artifical cochlear model and the intracochlear pressure changes were recorded in parallel with a micro-pressure sensor positioned in the apical region of the cochlea model to follow the maximum amplitude of intracochlear pressure. Four different sealing conditions were compared: 1) overlay, 2) overlay with fascia pushed in, 3) donut-like fascia ring, 4) donut-like fascia ring pushed in. RESULTS: We found statistically significant differences in the occurrence of maximum amplitude of intracochlear pressure peak changes related to sealing procedure comparing the different techniques. While the lowest amplitude changes could be observed for the overlay technique (0.14 mmHg ± 0.06) the highest values could be observed for the donut-like pushed in technique (1.79 mmHg ± 0.69). CONCLUSION: Sealing the electrode inserted cochlea can lead to significant intracochlear pressure changes. Pushing in of the sealing tissue cannot be recommended.

Surgical treatment of vertigo in cochlear implantees by electrode resealing.

CONCLUSION: Our present findings demonstrate that resealing to cover the electrode is an effective method to treat vertigo after CI. An insufficient cochleostomy sealing can be regarded as a cause of postoperatively newly occuring vertigo after CI. A transtympanic revision is a promising treatment option in cases of post-operative dizziness. Intoduction: A well-known and frequently reported complication after cochlear implantation is the appearance of postoperative vertigo symptoms. The aim of the present study was to observe if the postoperatively new occurrence of vertigo can be treated by resealing of the round window patch after cochlear implantation. MATERIAL AND METHODS: A retrospective analysis revealed that 10 patients underwent revision surgery transtympanally. Vertigo was assessed preoperatively and directly postoperatively and after 6 month after revision surgery by using the Dizziness Handycap Inventory (DHI). RESULTS: The most common symptom was rotating vertigo. A spontanous nystagmus was seen in four cases. No nystagmus was found after the revision surgery. In three cases, the onset of dizziness was associated with an event (sneezing, otitis media, climbing a mountain). A preoperative CT showed insuspectible results in seven patients but revealed pathologies two patients. Vertigo was improved significantly in six patients, and three of them were symptom-free.

Insertional depth-dependent intracochlear pressure changes in a model of cochlear implantation.

CONCLUSION: Over time, a homogenous increase in intracochlear pressure was seen in every experiment. Significant reductions in terms of amplitude variation and insertion depth were observed over time, using the one-point-supported insertion method. The frequency of peaks between the thirds was significantly lower when using the two-points-supported insertion method. OBJECTIVES: The preservation of residual hearing and minimization of intracochlear trauma are two of the major goals in modern cochlear implantation (CI) surgery. It is assumed that intracochlear pressure measurements yield information about the intracochlear behavior of the electrode itself in the cochlea. The aim of this study was to investigate temporal intracochlear fluid pressure changes using two different kinds of insertion conditions. METHOD: Cochlear implantations with the Advanced Bionics IJ® electrode were performed in an artificial cochlear model with a constant insertional speed of 0.5 mm/s provided by a linear actor. Amplitude pressure changes and number of pressure peaks were evaluated for every part. RESULT: Intracochlear fluid pressure changes are assumed to affect the preservation of residual hearing and should be minimized. The stability and reduction of movement of a lateral wall IJ® electrode increase at deeper insertion and affect intracochlear fluid pressure amplitude.

Comparison of the effects of four different cochlear implant electrodes on intra-cochlear pressure in a model.

CONCLUSION: Based on this model experiment, a small tip and low volume electrode show lowest intra-cochlear pressure values. Insertional support by a tool minimizes fast pressure changes. Higher electrodes volumes affect slow and fast pressure changes as well. OBJECTIVE: Insertion causing low intra-cochlear pressure is assumed to be important for atraumatic cochlear implant surgery to preserve residual hearing. Cochlear implant electrodes differ in terms of parameters like tip size, length, volume, and technique of insertion. The aim of this study was to observe the effect of different cochlear implant electrodes on insertional intra-cochlear pressure in a cochlear model. MATERIALS AND METHODS: Cochlear implant electrode insertions were performed in an artificial cochlear model and intra-cochlear pressure changes were recorded in parallel with a micro-pressure sensor positioned in the apical region of the cochlear model to follow the maximum values, temporal changes, maximum amplitude, and frequency of changes in intra-cochlear pressure. Insertions were performed with four different electrodes (Advanced Bionics 1j, Helix, HFMS, and LW23). RESULTS: This study found statistically significant differences in the occurrence of initial maximum pressure values correlating with the electrode tip size. The different electrodes and the technique of insertion significantly affected the occurrence of maximum value, amplitude, and frequency of intra-cochlear pressure occurrence.