Stapes Piston Research Articles

Effect of electromagnetic middle-ear implant simulating sites on the stapes spatial motion: A finite element analysis.

The electromagnetic middle-ear implant (MEI) is a new type of hearing device for addressing sensorineural and mixed hearing loss. The hearing compensation effect of the MEI varies depending on the transducer stimulation sites. This paper investigates the impact of transducer stimulation sites on MEI performance by analyzing stapes spatial motion. Firstly, we constructed a human-ear finite element model based on micro-CT scanning and inverse molding techniques. This model was validated by comparing its predictions of stapes spatial motion and cochlear response with experimental data. Then, stimulation force was applied at four common sites: umbo, incus body, incus long process and stapes to simulate the electromagnetic transducer. Results show that at low and middle frequencies, stapes-stimulating and incus-long-process-stimulating produce similar spatial motion to normal hearing; at high frequencies, incus-body-stimulating produces similar results to normal hearing. The equivalent sound pressure level generated by the stapes piston motion is less sensitive to the stimulation direction than that deduced by the stapes rocking motion.

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.

The Effect of Piston Diameter in Stapedotomy for Otosclerosis: A Temporal Bone Model.

The use of larger-diameter pistons in stapedotomy leads to better hearing outcomes compared with the use of smaller-diameter pistons. There is an interaction between stapes piston diameter and fenestration diameter. Otosclerosis can be treated surgically by removing part of the stapes and bypassing the stapes footplate with a prosthesis. Available piston shaft diameters range between 0.3 and 0.8 mm. There has been a tendency toward the use of smaller-diameter pistons, because of a suspected decreased risk of cochlear trauma and subsequent sensorineural hearing loss (SNHL) with smaller pistons. However, mathematical models, temporal bone studies, and clinical studies suggest that the use of larger-diameter pistons is associated with better hearing outcomes. Three fresh-frozen, non-pathologic temporal bones were harvested from human cadaveric donors. Acoustic stimuli in the form of pure tones from 250 to 8000 Hz were generated at 110 dB sound pressure level. A total of 16 frequencies in a 1/3-octave series were used. Stapes and round window velocities in response to the acoustic stimuli were measured at multiple equally spaced points covering the stapes footplate and round window using a scanning laser Doppler interferometry system. Eight sets of measurements were performed in each temporal bone: 1) normal condition (mobile stapes), 2) stapes fixation and stapedotomy followed by insertion of 3) a 0.4-mm-diameter piston in a 0.5-mm-diameter fenestration, 4) a 0.4-mm-diameter piston in a 0.7-mm-diameter fenestration, 5) a 0.4-mm-diameter piston in a 0.9-mm-diameter fenestration, 6) a 0.6-mm-diameter piston in a 0.7-mm-diameter fenestration, 7) a 0.6-mm-diameter piston in a 0.9-mm-diameter fenestration, and 8) a 0.8-mm-diameter piston in a 0.9-mm-diameter fenestration. At midrange frequencies, between 500 and 4000 Hz, round window velocities increased by 2 to 3 dB when using a 0.6-mm-diameter piston compared with a 0.4-mm-diameter piston. Using a 0.8-mm-diameter piston led to a further increase in round window velocities by 2 to 4 dB. Our results suggest a modest effect of piston diameter on hearing results following stapedotomy.

Revision stapedectomy with bone cement: are results comparable to those of standard techniques?

To examine hearing results in revision stapedectomy using hydroxyapatite bone cement for incus necrosis. Retrospective case series. Tertiary care academic medical center. Eligible patients underwent revision stapedectomy for otosclerosis using hydroxyapatite bone cement to reconstruct incus necrosis between March 2007 and August 2013. Patients were excluded for insufficient audiometric data or an operative indication other than otosclerosis. Revision stapedectomy performed with standard stapes piston prostheses using hydroxyapatite bone cement to stabilize the prosthesis. Air-bone gap (ABG), air-conduction and bone conduction pure-tone audiometry thresholds, and speech discrimination scores (SDSs) were obtained preoperatively and postoperatively. The preoperative result closest to the date of surgery was compared with the postoperative result farthest from the date of surgery. Twenty-seven patients (aged 32-83 yr) met criteria and were included in the study. Average duration of follow-up was 7 months (range, 1-39 mo). Postoperative closure of the ABG to within 10 dB was achieved in 77.8% of cases. Closure to within 20 dB was achieved in 96.3%. The average postoperative ABG was 8.1 dB (range, 0-24 dB). The average SDS change was +7.4% (-12% to +92%). There were no cases of significant postoperative sensorineural hearing loss by bone conduction pure-tone audiometry. Use of hydroxyapatite cement for treatment of incus necrosis in revision stapedectomy provides excellent hearing outcomes and is a reasonable alternative to total ossicular reconstruction prosthesis or malleovestibular prosthesis techniques.

Three-Dimensional Vibration of the Malleus and Incus in the Living Gerbil

In previous studies, 3D motion of the middle-ear ossicles in cat and human was explored, but models for hearing research have shifted in the last few decades to smaller mammals, and gerbil, in particular, has become a popular hearing model. In the present study, we have measured with an optical interferometer the 3D motion of the malleus and incus in anesthetized gerbil for sound of moderate intensity (90-dB sound pressure level) over a broad frequency range. To access the ossicles, the pars flaccida was removed exposing the neck and head of the malleus and the incus from the malleus-incus joint to the plate of the lenticular process. Vibration measurements were done at six to eight points per ossicle while the angle of observation was varied over approximately 30° to enable calculation of the 3D rigid-body velocity components. These components were expressed in an intrinsic reference frame, with one axis along the anatomical suspension axis of the malleus-incus block and a second axis along the stapes piston direction. Another way of describing the motion that does not assume an a priori rotation axis is to calculate the instantaneous rotation axis (screw axis) of the malleus/incus motion. Only at frequencies below a few kilohertz did the screw axis have a maximum rotation in a direction close to that of the ligament axis. A slight slippage in the malleus-incus joint developed with increasing frequency. Our findings are useful in determining the sound transfer characteristics through the middle ear and serve as a reference for validation of mathematical middle-ear models. Last but not least, comparing our present results in gerbil with those of previously measured species (human and cat) exposes similarities and dissimilarities among them.

Our Experience with the Titanium Soft Clip Piston Stapedotomy

The crimping of stapes prosthesis to the long process of incus has always been the bugbear of an otologist. Malcrimping on one hand can lead to necrosis of the long process on the other it can lead to a residual air-bone gap or a postoperative reappearance of the conductive hearing loss. To solve these problems different types of stapes prostheses having different techniques to achieve a secure attachment to incus have been devised. Retrospective analysis of patient data. Tertiary care hospital. Case records of 20 patients of otosclerosis who had undergone stapedotomy using titanium soft clip stapes piston (Kurz, Germany) were retrospectively analysed. This new type of stapes piston is a modification of the earlier àWengen clip piston (Kurz, Germany) which was designed to avoid the crimping onto the incus in stapedotomy. Hearing results were analyzed using American Academy of Otolaryngology-Head and Neck Surgery guidelines including 4 frequency pure tone average. The mean postoperative air-bone gap was with in 10dB in 8 (40% of cases), up to 15dB in another 8 (40%) cases and in rest 4 (20%) was with in 20dB. No adverse reactions occurred during follow-up. The use of the titanium soft clip stapes piston gives good results in cases of stapedotomy for otosclerosis. The soft clip design is a new development in the evolution of stapes piston prostheses. Surgical introduction, placement, and fixation are easier than the earlier àWengen design of clip piston.

Comparison of Nitinol Stapes Pistons with Conventional Stapes Pistons: A Cadaver Study

Objective. To visually compare the Nitinol “smart” stapes prosthesis to conventional manual crimping stapes pistons in temporal bone cadaver specimens. Main Outcome Measures. 10 otolaryngologists were given a photograph of the randomly ordered stapes pistons and asked to use the pictures to answer questions about each stapes piston. The answers to the survey were then recorded for analysis. Results. 8 of 9 Nitinol pistons were described as circular, and 3 of 9 manual crimped pistons were described as circular (P < .05). 6 of 9 Nitinol pistons were considered to be in contact with >66% of the incus and 3 of 9 to be in contact with 34–66% of the incus. 3 of 9 manually crimped pistons were considered to be in contact with >66% of the incus, 3 with 34–66% contact and 3 with less than 34% contact. Conclusions. The Nitinol “smart” stapes pistons were considered to provide a more circular and circumferential crimping and to have greater contact with the long process of the incus than conventional stapes pistons.

Three-Dimensional Analysis of the Vestibular End Organs in Relation to the Stapes Footplate and Piston Placement

Measurements of the proximity of the membranous labyrinth to the stapes footplate show considerable variation. Largely, such measurements have been from histologic sections of fixed temporal bones, which may be affected by shrinkage artifact and perspective distortion in the 2-dimensional plane. To overcome these problems, the present study undertook an analysis of the 3-dimensional (3D) architecture of the relationship of the stapes to the membranous labyrinth using high-resolution X-ray micro-computed tomography. Eleven temporal bones were fixed with Karnovsky's fixative (known to minimize shrinkage), soaked in 2% osmium tetroxide, and scanned in a micro-computed tomography scanner. The otic capsule was intact to exclude sectioning artifact, and no alcohol was used to avoid tissue shrinkage. Measurements were taken in a vertical plane to provide distances from the utricle and saccule to the footplate, and 3D reconstruction of the spatial relationship of these structures was carried out. The relationship of these structures to a stapes piston also was studied. The safest area of piston placement was the central and inferior part of the footplate. This was safe up to 0.5 mm depth at all areas except posterosuperiorly where the utricular macula is, on average, only 0.61 mm away from the footplate. The angle of insertion of the piston also influences the end result. Two-dimensional information about vestibular end organ location should serve as a guideline only because the operative field is 3D, and the relationship of the piston to the vestibular labyrinth changes with the angle of placement.

Analysis of the accuracy of high-resolution computed tomography techniques for the measurement of stapes prostheses

Severe cochleovestibulopathy is a complication after stapes plasty and CT may be needed to assess intravestibular intrusion depth of the stapes piston. The accuracy of modern CT systems in this task has not been established. Stapes plasty was performed on six cadaver ears, and Soft CliP titanium pistons were inserted. Specimens were then examined using three different CT systems: single source 64-row, dual source 64-row and flat-panel computed tomography (FD-CT). Piston length, width and intravestibular intrusion were measured by four independent observers. Temporal bone dissection was then performed and vestibular piston intrusion measured microscopically. Piston dimensions were overestimated by all observers and CT systems. Intravestibular penetration as assessed by CT was consistently greater than the value found on cadaveric anatomical dissection. On average, the CT measurement of width was 0.176 mm (44%) greater, length 0.125 mm (6.25%) greater and intrusion 0.333 mm (39.2%) greater than the anatomical measurements. FD-CT showed better image quality and partly less bias in several measurements, but penetration depth was still variably overestimated. CT measurement consistently overestimated intravestibular piston dimensions and vestibular intrusion. Modern temporal bone imaging systems are not yet able to depict the stapes piston position with a sufficient degree of accuracy.

Assessing Stapes Piston Position Using Computed Tomography

Temporal bone computed tomographic (CT) scanning in the postoperative stapedotomy patient is inaccurate in assessing stapes piston position within the vestibule. Poststapedotomy patients that have persistent vertigo may undergo CT scanning to assess the position of the stapes piston within the vestibule to rule out overly deep insertion. Vertigo is a recognized complication of the deep piston, and CT evaluation is often recommended. The accuracy of CT scan in this setting is unestablished. Stapedotomy was performed on 12 cadaver ears, and stainless steel McGee pistons were placed. The cadaver heads were then scanned using a fine-cut temporal bone protocol. Temporal bone dissection was performed with microscopic measurement of the piston depth in the vestibule. These values were compared with depth of intravestibular penetration measured on CT scan by 4 independent measurements. The intravestibular penetration as assessed by computed tomography was consistently greater than the value found on cadaveric anatomic dissection. The radiographic bias was greater when piston location within the vestibule was shallower. The axial CT scan measurement was 0.53 mm greater, on average, than the anatomic measurement. On average, the coronal CT measurement was 0.68 mm greater than the anatomic measurement. The degree of overestimation of penetration, however, was highly inconsistent. Standard temporal bone CT scan is neither an accurate nor precise examination of stapes piston depth within the vestibule. We found that CT measurement consistently overstated intravestibular piston depth. Computed tomography is not a useful study in the evaluation of piston depth for poststapedectomy vertigo and is of limited value in this setting.

Simultaneous Measurements of Ossicular Velocity and Intracochlear Pressure Leading to the Cochlear Input Impedance in Gerbil

Recent measurements of three-dimensional stapes motion in gerbil indicated that the piston component of stapes motion was the primary contributor to intracochlear pressure. In order to make a detailed correlation between stapes piston motion and intracochlear pressure behind the stapes, simultaneous pressure and motion measurements were undertaken. We found that the scala vestibuli pressure followed the piston component of the stapes velocity with high fidelity, reinforcing our previous finding that the piston motion of the stapes was the main stimulus to the cochlea. The present data allowed us to calculate cochlear input impedance and power flow into the cochlea. Both the amplitude and phase of the impedance were quite flat with frequency from 3 kHz to at least 30 kHz, with a phase that was primarily resistive. With constant stimulus pressure in the ear canal the intracochlear pressure at the stapes has been previously shown to be approximately flat with frequency through a wide range, and coupling that result with the present findings indicates that the power that flows into the cochlea is quite flat from about 3 to 30 kHz. The observed wide-band intracochlear pressure and power flow are consistent with the wide-band audiogram of the gerbil.

Stellenwert der CT-Diagnostik vor Revisions-Stapedotomien

Stapedectomy and, more recently, stapedotomy have been widely accepted as the primary surgical techniques to improve conductive hearing in patients suffering from otosclerosis. Unsuccessful outcomes are infrequent, but revision surgery may become necessary. We have analyzed the value of computed tomography (CT) scanning following unsuccessful stapes surgery. In a total of 37 CT scans, the depth of insertion, angle between prosthesis and footplate, location of prosthesis within the oval niche, visibility of the prosthesis, dehiscence of the superior semicircular canal, and extent of otospongiotic foci were evaluated and compared with the audiometric results. There was no significant correlation between CT parameters and audiologic results, except for patients with cochlear otosclerosis or lateral dislocation of the piston. One previously unknown dehiscence of the superior semicircular canal was diagnosed. Otospongiotic foci were seen in 13 ears (35%). Displacements of the stapes piston and rare causes for an insufficient result, such as a dehiscence of the superior semicircular canal, can be diagnosed accurately by CT. However, correlation between the audiologic results and the findings on CT scans was possible in only a few cases. Nevertheless, CT scans provide additional information for surgical planning in revision stapes surgery and may become increasingly important to reduce unanticipated intraoperative risks; they may even guide the surgeon not to perform unnecessary revision surgeries.

Eliminating the Limitations of Manual Crimping in Stapes Surgery: Mid‐Term Results of 90 Patients in the Nitinol Stapes Piston Multicenter Trial

To present our mid-term results of our multicenter study using the Nitinol self-crimping stapes piston, focusing on the interindividual variations of postoperative air-bone gap closures (ABGC), postoperative hearing results, and postoperative recurrences of conductive hearing loss and to compare these findings with our pilot group of patients. Prospective, multicenter cohort study involving three academic tertiary care referral centers from Australia, Switzerland, and the United States. Ninety patients with otosclerosis undergoing laser-stapedotomy with the Nitinol stapes piston were matched to reference patients from our titanium piston database. The effects of the self-crimping Nitinol piston on the postoperative ABGC, the postoperative interindividual air-bone gap (ABG) variations, and the postoperative hearing results were investigated 3, 6, 12, 18, and 24 months postoperatively. These data were statistically compared with the results of the control patients in our titanium stapes piston database and the results of our previously published pilot study. The mean postoperative ABG and the interindividual variations of the postoperative ABG continue to be significantly smaller in the Nitinol group; the extent of ABGC now is significantly larger in the Nitinol piston group. The postoperative mid-term stability of ABGC was similar in both groups. No adverse reactions occurred during follow-up. Our mid-term results continue to show that the self-crimping shape memory alloy Nitinol stapes piston overcomes the limitations of manual malcrimping in stapedotomy, thus simplifying and optimizing the surgical procedure. This so far has allowed reliable, safe, and consistent ABGC in patients with otosclerosis.

Rotational tomography of the normal and reconstructed middle ear in temporal bones: an experimental study

Imaging is an essential diagnostic tool in reconstructive middle ear surgery, especially in pre-operative planning. Due to ongoing improvement of imaging quality and development of new imaging techniques like e.g. rotational tomography (RT) post-operative follow-up and immediate evaluation of surgical results may become more important. The aim of this experimental study was to evaluate RT as a new tool for postoperative determination of middle ear anatomy and implant position in temporal bones. RT was performed in ten temporal bone specimen after insertion of different middle ear prostheses concerning material, shape and length (PORP; TORP; Stapes piston). An implantable hearing device (Symphonix Soundbridge) was also implanted and visualized. For comparison some specimen additionally underwent conventional computed tomography (CT), including the newest technology. Characterization of anatomical structures of the temporal bone using RT was of comparable quality to conventional CT-scans in all investigated specimen while requiring approximately 30% of the CT's irradiation exposure. Unlike CT the RT showed almost no problems due to metallic artefacts of the implanted prostheses. Furthermore RT enabled a 3-dimensional view of the temporal bone and angle determination of inserted prostheses towards the tympanic membrane and/or the malleus handle. Detailed imaging of the prostheses allowed determination of shape, material and localization within the specimen's reconstructed middle ear. The new imaging technique of RT allows precise presentation of anatomical structures and middle ear implants in temporal bones. Following these experimental results it will be our future work to evaluate this method in clinical practise.

Comparison of Titanium and Robinson Stainless Steel Stapes Piston Prostheses

Although stainless steel stapes prostheses have generally been considered magnetic resonance imaging safe, there is concern that this may change with the development of more powerful imaging systems. The objective of the study was to determine whether a titanium piston stapes prosthesis would be audiometrically and surgically equivalent to a Robinson stainless steel piston for stapedectomy. Retrospective chart review. Private otology practice. In all, 50 patients underwent stapedectomy with a Gyrus titanium piston prosthesis. These patients were matched on the basis of age and preoperative bone-conduction scores with patients who underwent stapedectomy with a Robinson stainless steel piston prosthesis. Audiometric results are analyzed, and surgical complications noted. There was no significant difference between groups in hearing improvement or postoperative air-bone gap. The mean four-frequency hearing improvement was 27.7 dB for the stainless steel group and 27.8 dB for the titanium group. The mean postoperative air-bone gap was 2.65 dB for the stainless steel group and 2.60 for the titanium group. Neither group had a surgical complication. The titanium stapes prosthesis is a good alternative to a stainless steel prosthesis.

First Experience with a New Stapes Clip Piston in Stapedotomy

Hearing results after 23 implantations of a newly designed titanium-clip stapes piston prosthesis (the àWengen Clip Piston prosthesis) in patients with otosclerosis were evaluated. This new type of stapes piston was designed to avoid the crimping onto the incus in stapedotomy. This one clip fits all designs and enables solid fixation by clicking the prosthesis onto the long process of the incus without crimping. A retrospective pilot study was carried out by microcomputer of the preoperative and postoperative audiological results of patients in whom the titanium-clip stapes piston prosthesis was implanted. Ear, nose and throat department of Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. 23 Patients underwent a stapedotomy for hearing improvement suffering from otosclerosis. implantations of a newly designed titanium-clip stapes piston prosthesis (the àWengen Clip Piston prosthesis) in patients with otosclerosis were evaluated. The stapedotomy was performed with the àWengen Clip Piston prosthesis. Pre and postoperative audiograms were used to evaluate the hearing gain improvement with the new stapes piston. Especially we looked at the airbone gap closure and the sensorineural hearing after the surgical procedure and compared these with the ones before surgery. The hearing results showed a closure of the pure-tone average air-bone gap to within 10 dB in 56.6% of cases (10 of 23 implantations) and to within 20 dB in 100% (23 of 23 implantations). A residual air-bone gap of greater than 20 dB was seen in the present pilot study. Postoperative overclosure of bone-conduction thresholds was discovered only for the frequency of 2 kHz. Sensorineural hearing loss greater than 10% did not occur, and there was no decline in the speech discrimination. The use of a newly designed titanium-clip stapes piston prosthesis with a diameter of 0.4 mm gives good results in cases of stapedotomy for otosclerosis. The titanium-clip design is a new development in the evolution of stapes piston prostheses. Surgical introduction, placement, and fixation are not always easy, depending on the anatomy of the middle ear and the thickness of the fixation area on the long process of the incus.

Eliminating the Limitations of Manual Crimping in Stapes Surgery? A Preliminary Trial with the Shape Memory Nitinol Stapes Piston

Manual piston malcrimping in stapedotomy may be the major cause of the occurrence of the significant, interindividual variations of postoperative air-bone gap (ABG), air-bone gap closures (ABGC), and postoperative recurrences of conductive hearing loss. To eliminate the effects of manual crimping on stapedotomy outcomes, the self-crimping, shape memory alloy Nitinol stapes piston was investigated and hearing evaluated. Prospective, preliminary case-control study in a tertiary care referral center. Sixteen patients with otosclerosis undergoing reversed stapedotomy using the Nitinol stapes piston were matched to reference patients out of our conventional titanium piston database. The effects of the self-crimping Nitinol piston on the postoperative ABGC, the postoperative air-bone gap (ABG) variations, and the postoperative short-term hearing results were investigated 3, 6 and 9 months postoperatively. These data were statistically compared with the results of the control patients in our titanium stapes piston database. The mean postoperative ABG and the interindividual variations of the postoperative ABG were significantly smaller in the Nitinol group, the extent of ABGC greater in the Nitinol piston group, but not significant. The postoperative short-term stability of ABGC was similar in both groups. No infections or adverse reactions occurred during follow-up. Our preliminary results suggest that the self-crimping shape memory alloy Nitinol stapes piston eliminates the limitations of manual malcrimping in stapedotomy, thus optimising the surgical procedure. This allows reliable, safe, and consistent air-bone-gap closure in patients with otosclerosis up to 1 year after surgery.

Stapes prosthesis attachment: the effect of crimping on sound transfer in otosclerosis surgery.

Although in stapes surgery successful hearing improvement may be achieved in the majority of patients, unsatisfactory closure of the air-bone gap can be recorded. One of many reasons for unexpected failures of stapes surgery may be the insufficient crimping of a stapes prosthesis onto the incus. The objectives of the study were to assess the amount of sound transmission loss in response to the quality of prosthesis crimping and to identify a required loop attachment pattern to obtain good sound transmission results. Experimental. A temporal bone model was developed to measure the sound transmission properties between incus and prosthesis on 17 fresh human temporal bones. The attachment of a titanium stapes piston was assessed without crimping, followed by loose crimping and tight fixation to the incus, using scanning laser Doppler interferometry, endoscopic photography, micro grinding technique, and scanning electron microscopy. An algorithm had to be developed to simulate acoustical stimulation using electromechanical stimulation. Optimal tight crimping of the stapes piston revealed consistent good sound transfer function ranging from 0 to 7 dB loss, and loss remained, on average, at 2 dB. The mean transmission losses for conditions of loose crimping and no crimping were surprisingly small (within 10 dB). However, these unusual crimping conditions allowed a wide range of losses up to 28 dB. A close coupling at least at two opposite points was obligatory to obtain consistently good results. Perfect hearing reconstruction necessitates ideal crimping of a prosthesis to obtain consistently good results. However, the final functional gain depends on many different intraoperative and postoperative factors.

Sichere Fixierung von Cochlear-Implant-Elektrodenträgern bei Kindern und Erwachsenen - erste Erfahrungen mit einem neuen Titan-Clip

There is a reported 1% incidence of delayed migration of extrusions of the electrode arrays out of the cochlea. A titanium clip to fix the electrode array of the MED EL Combi 40 Cochlear Implant System is described. The clip is designed and shaped in a double U configuration. The clip material allows easy adaption to the individual anatomical situation. The clip is fixed to a bony bridge at the incus bar and fixes the electrode in a plane parallel to the chorda facial angle. It is closed around the electrode similarly to a stapes piston around the incus. Additional tests which examined the possible risk of damaging the electrode carrier and clinical findings are described. The clip was used in 23 cases with a follow-up period up to 1 year. No signs for dislocation of the electrode were found. In one revision case the clip was covered with a thin mucosal layer. The electrode array showed no signs of damage. Intraoperative findings confirmed the experimental tests on the electrode fixation. The titanium clip facilitates safe and quick fixation of the electrode array and prevents dislocation. its flexibility and shape minimizes the risk of damage.