Electrode Extrusion Research Articles

An Evaluation of the Surgical Trauma to Intracochlear Structures After Insertion of Cochlear Implant Electrode Arrays: A Comparison by Round Window and Antero-Inferior Cochleostomy Techniques.

To evaluate the extent of intracochlear damage by histologic assessment of cadaveric temporal bones after insertion of cochlear implants by: round window approach and cochleostomy approach. Cochlear implantation was performed by transmastoid facial recess approach in 10 human cadaveric temporal bones. In 5 temporal bones, electrode insertion was acheieved by round window approach and in the remaining 5 bones, by cochleostomy approach. The bones were fixed, decalcified, sectioned and studied histologically. Grading of insertion trauma was assessed. In the round window insertion group, 2 bones had to be excluded from the study: one was damaged during handling with electrode extrusion and another bone did not show any demonstrable identifiable cochlear structure. Out of the 3 temporal bones, a total of 35 sections were examined: 24 demonstrated normal cochlea, 4 had basilar membrane bulging and 7 had fracture of bony spiral lamina. In the cochleostomy group, histology of 2 bones had to be discarded due to lack of any identifiable inner ear structures. Out of the 3 bones studied, 18 sections were examined: only 3 were normal, 4 sections had some bulge in spiral lamina and 11 had fracture of bony spiral lamina. The fracture of spiral lamina and bulge of basement membrane proportion is relatively higher if we perform cochleostomy as compared to round window approach. Therefore, round window insertion is relatively less traumatic as compared to cochleostomy. However, our sample size was very small and a study with a larger sample is required to further validate these findings.

Use of Pericranial Flap Coverage in Cochlear Implantation of the Radical Cavity: Rationale, Technique, and Experience.

Cochlear implant (CI) surgery in the setting of an open mastoid cavity is evolving. Two strategies are commonly pursued: a staged approach, clearing the disease, closing the meatus or the external auditory canal (EAC), and reevaluating in 3 to 6 months prior to implantation, or a single-stage procedure with mastoid obliteration without EAC closure. Meatal closure is often employed in the setting of an open mastoid cavity to reduce the risk of electrode extrusion and infection. An open cavity offers the advantages of being a single-stage procedure, permitting direct surveillance for recurrent cholesteatoma, and reducing the need for repeat computed tomography scans. We describe an approach to the coverage of a CI within a dry, open mastoid cavity using an anteriorly-based postauricular pericranial flap.

Cochlear re-implantation: lessons learnt and the way ahead

Conclusion A cochlear re-implantation procedure is undesirable; however, the cochlear implant surgeon may have to perform a re-implantation procedure occasionally for various reasons. Following standard techniques, implant performance comparable with primary implantation may be achieved. Objective To study the causes and outcomes of cochlear re-implantation in an Asian Indian population. Study design Retrospective analysis of clinical charts over an 18-year period with prospective follow-up of patients. Methods The charts of 534 patients, who underwent cochlear implant, at an Otorhinolaryngology institutional Centre, from January 1997 to January 2015 were studied. Of these, the charts of 18 patients who underwent cochlear re-implantation were studied. The causes and audiological and speech outcomes were analysed. Results Eighteen patients (3.4%) underwent cochlear re-implantation for various reasons. The commonest indication was device failure in seven patients (39%), followed by electrode extrusion in five (28%), trauma in three (11%), electrode migration in two (11%) and improper electrode placement in one (6%) patient. The audiological performance tests and speech tests either remained the same or improved from those achieved for patients undergoing primary implantation, in 87% patients.

Non-mastoidectomy Cochlear Implant Approaches: A Literature Review.

Introduction Posterior tympanotomy approach for cochlear implant (CI) surgery, has been the most commonly used worldwide with current 0.7% rate of facial nerve injury. Non-mastoidectomy CI approaches include the suprameatal approach (SMA) and its modifications, the transcanal approach and its modifications and the pericanal approach for electrode insertion. Objectives The objective of this study was to review the literature regarding non-mastoidectomy CI approaches. Data Synthesis A search was performed in the LILACS, MEDLINE, SciELO, PubMed databases and Cochrane Library in February 2015, and the key words used in the search were CI, SMA, transcanal approach, pericanal approach, or electrode extrusion. About 30 studies that met the criteria described in “Study Selection” were read in full. The studies showed 1014 patients that underwent CI by SMA or its modifications, 266 CI patients treated by transcanal approach or its modifications, and 15 patients implanted by the pericanal approach. Reported complication with SMA was 99 (9.8%) minor and 13 (1.3%) major. With transcanal, there were 24 complications; 19 (7.1%) minor and 5 (1.9%) major. No post-operative complication was reported in pericanal approach. Studies showed no reported facial nerve paresis or paralysis in all non-mastoidectomy approaches. Conclusion Complications rates with non-mastoidectomy approaches are similar to those found in the mastoidectomy approach. Thus, non-mastoidectomy approaches may be an alternative in cases where the conventional mastoidectomy approach is difficult to perform. It would be helpful for CI surgeons to become familiarized with these approaches.

Occupational exposure to polycyclic aromatic hydrocarbons: relations between atmospheric mixtures, urinary metabolites and sampling times.

Occupational exposure to polycyclic aromatic hydrocarbons (PAHs) can be assessed by either air monitoring or biomonitoring using urinary 1-hydroxypyrene (1-OHP) or 3-hydroxybenzo(a)pyrene (3-OHBaP). The aim of this study was to understand the links between atmospheric PAHs and urinary metabolites, in order to improve the biomonitoring strategy for assessing carcinogenic risk. Personal air sampling for pyrene and BaP measurements, and urines for 1-OHP and 3-OHBaP analyses of seven workers from electrode production plant were collected every day of the working week. High variability of atmospheric levels between activities and between days was observed, especially for gaseous pyrene. No correlation was found between urinary metabolites: 1-OHP maximum levels occurred for "electrode extrusion" activity; those of 3-OHBaP occurred for "raw materials dispatcher." Sixty percentage of 3-OHBaP maximum levels were observed in urines collected at the beginning of shift the last workday. Those of 1-OHP occurred at different sampling times, depending on the gaseous pyrene levels (not stopped by P3 respirators). Dermal absorption of PAHs was confirmed by significant effect of particulate pyrene on 1-OHP in the samples collected the morning of the following day (p < 0.02, n = 25). Lack of correlation between metabolites concentrations emphasizes the non-relevance of 1-OHP, from a non-carcinogenic gaseous and particulate compound, and the great interest of 3-OHBaP, from carcinogenic BaP. Its slower urinary elimination prevents the risk of exposure underestimation, and urinary analysis should be performed at the beginning of shift the end of working week, especially in case of high exposure variability.

Complications in Cochlear Implantation at the Clinical Center of Vojvodina.

The first modern cochlear implantation in Serbia was performed on November 26, 2002 at the Center for Cochlear Implantation of the Clinic for Ear, Nose and Throat Diseases, Clinical Center of Vojvodina. The aim of the paper is the analysis of intraoperative and postoperative complications. Major complications include those resulting in the necessity for revision surgery, explantation, reimplantation, severe disease or even lethal outcomes. Minor complications resolve spontaneously or can be managed by conservative therapy and do not require any prolonged hospitalization of the patient. In the 2002-2013 period, 99 patients underwent surgical procedures and 100 cochlear implants were placed. Both intraoperative and postoperative complications were analyzed in the investigated patient population. The analysis encompassed 99 patients, the youngest and the oldest ones being one year old and 61 years old, respectively. The complications were noticed in 11 patients, i.e. in 10.5% of 105 surgical procedures. The majority of procedures (89.5%) were not accompanied by any post-surgical complications. Unsuccessful implantation in a single-step procedure (4.04%) and transient facial nerve paralysis can be considered most frequent among our patients, whereas cochlear ossification (1.01%) and transient ataxia (2.02%) occurred rarely. Stimulation of the facial nerve (1.01%), intraoperative perilymph liquid gusher (1.01%), device failure and late infections (1.01%) were recorded extremely rarely. Complications such as electrode extrusion, skin necrosis over the implant or meningitis, which is considered the most severe postoperative complication, have not been recorded at our Center since the very beginning. Absence of postoperative meningitis in patients treated at the Center can be attributed to timely pneumococcal vaccination of children.

Intracochlear inflammatory response to cochlear implant electrodes in humans.

This study evaluates the types and degrees of tissue response adjacent to the electrode of multichannel cochlear implants. Cochlear implant electrodes have been classified as biocompatible prostheses. Nevertheless, in some reports, electrode extrusion, chronic inflammation, and even soft failure of the implant system have been attributed to a tissue response to the electrode. All celloidin-embedded temporal bones with multichannel cochlear implants from the temporal bone collection of the Massachusetts Eye and Ear Infirmary were included in the study. A total of 28 temporal bones from 21 subjects were identified and processed for histology. The severity of cellular response including eosinophil and lymphocytic infiltration, giant cell reaction, new bone formation, and fibrosis were scored on a scale from 0 to 3 at three 1-mm segments along the electrode: first 1 mm at the cochleostomy, last 1 mm from the tip of the electrode, and midway between these proximal and distal segments. The values were compared using the Wilcoxon test. A granulomatous reaction to the electrode was observed in 27 (96.4%) temporal bones. Eosinophil infiltration was observed in 7 (25%) temporal bones, suggesting an allergic reaction. The Inflammatory response to the electrode was significantly greater at the basal turn of cochlea close to the cochleostomy (p < 0.05) than distal to it. An inflammatory response is common after cochlear implantation, and it is more robust at the cochleostomy than distal to it, suggesting the role of trauma of insertion as a contributing factor.

EVALUATION OF THE RESULTS OF DIFFERENT PROCEDURES IN COCHLEAR IMPLANTATION.

The cochlear implantation has radically changed the outlook for profoundly deaf adults and children. The cochlear implant can provide sufficient hearing sensations to enable most severely or profoundly deafened persons to continue communicating using speech as their primary means of communication .In Classic cochlear implantation; mastoidectomy is done to help retain the electrode leads within the confines of the mastoid cavity. Then the facial recess should be widely opened followed by cochleostomy which is followed by insertion of the electrode array. Minimally invasive cochlear implant surgery has become the mainstay of most experienced centers. Aim of work: to evaluate the results of using different procedures in cochlear implantation. Patients and methods: The study carried out on 41 patients have done cochlear implantation, starting from April 2011 till April 2014, and we excluded postlingual adults and children with congenital anomalies ,post-meningitis cochlear ossification and children with chronic suppurative otitis media (n=7). The patients were divided into two groups: the 1st group of patients was implanted by classic approach the 2nd group of patients was implanted by the SMA and another comparison in which, the patients were divided into two groups: the 1st group of patients was implanted by PULSAR ci100 device the 2nd group of patients was implanted by HI-RES 90K device; all patients were subjected to full preoperative assessment, and full postoperative assessment of complications (major and minor complications). Results: there is significant relation between the two groups regarding major complications in favor to classic approach but there is significant danger of facial nerve, chorda tympani nerve injury in classic approach, there is no significant difference between the ways of insertion regarding the major complications and there is significant difference between the 2 groups as regard to device migration, electrode extrusion and device malfunction in favor to Hi-res 90k device. Conclusion: classic approach has fewer incidences of major and minor complications than SMA, but there is significant danger of facial nerve, chorda tympani nerve injury in classic approach, Hi-res 90k device is better than PULSAR ci100 device as regard to device migration, electrode extrusion and device malfunction, We still need more assessment for surgical approaches, way of electrode insertion, type of devices. Keywords: Cochlear implantation, Suprameatal approach, Posterior tympanotomy approach.

Numerical analysis of friction influence and die geometry on the quality of product in the forward extrusion process of tubular copper electrodes

The results of a numerical analysis of the extrusion of tubular electrolytic-copper electrodes are presented. The numerical analysis is based on the finite-element method (FEM) in DEFORM software. This method makes it possible to predict the formation of a microstructure, characteristics of the material, and factors in the process that improve the mechanical properties of the articles.

Subtotal Petrosectomy and Mastoid Obliteration in Adult and Pediatric Cochlear Implant Recipients

To investigate the effect of subtotal petrosectomy and mastoid obliteration (SPMO) on the overall success of adult and pediatric cochlear implant (CI) recipients. Retrospective case series. Tertiary care referral center. Thirty-nine ears in 36 patients (23 adults and 13 children) received both surgeries between 1990 and 2012. CI candidates underwent SPMO to permit implantation and minimize the risks of infectious complications in the recipient ear. SPMO was performed before (69.3%), at the time of (25.6%), and after CI (5.13%). Mastoids were obliterated with fat (30.8%), muscle (66.7%), and bone pate (2.56%). Feasibility, complications, and success of SPMO and CI were assessed with standard statistical analysis and Fisher's exact test with 2-sided p values. Ear disease was definitively managed, and CI was successfully placed in all but one case. Complications including abscess (n = 3), subcutaneous emphysema (n = 1), ear canal granulation formation (n = 1), and electrode extrusion (n = 1) occurred in 15.4% of patients. Predisposing syndromes were present in children more often than adults (43.8% versus 13.0%, p = 0.0598). Adults more often than children had previous mastoid surgery for middle ear disease (30.4% versus 0.0%, p = 0.0288). CIs were placed under local anesthetic and sedation (n= 3) and after radiation treatment for nasopharyngeal cancer (n = 2) in adult ears. SPMO is an effective and safe procedure for definitively managing middle ear disease and implanting adult and pediatric CI candidates.

Superhigh-speed extrusion of tungsten-free electrodes for electrospark alloying of steel 45

In the present work, we develop tungstenfree elec� trode materials that improve the effectiveness of elec� trospark alloying by reducing the erosive strength of the electrode materials. The physicochemical and operational characteristics of the alloyed layers are improved by introducing boronbearing materials that reduce the grain size of the electrode materials obtained by superhighspeed extrusion. In addition, variation of the parameters of the electrospark dis� charge permits nanostructuring of the alloyed layers. TiCbased batch for electrode materials is made by mixing Ti, No, Mo and DTC powder with soot in a ball mill for 4 h. Cylindrical blanks are produced from this batch by preliminary pressing in a mold. The elec� trodes are produced by superhighspeed extrusion at the Institute of Structural Macrokinetics and Materi� als Science (Chernogolovka). In electrospark alloying, the change in mass of the cathode (steel 45) and erosion products from the anodes (TiC-Ni-Mo, with DTC additive) is deter� mined as a function of the alloying time, with various electrical parameters. The composition of the elec� trode materials is as follows:

Cochlear implantation in patients with radical mastoid cavities

In the past, cochlear implantation was a contraindicated procedure in profoundly deaf patients with radical mastoid cavities. This was due to high risk of infection spread into the cochlea with possible destruction of the remainder surviving cochlear neural elements. We report on King Abdulaziz University Hospital, Riyadh, Saudi Arabia experience in managing, two postlingual profoundly deaf patients (both male and adult) with radical mastoid cavities due to chronic cholesteatomatous otitis media by cochlear implantation. Two different open techniques were used, cochlear implantation with (in the first patient) and without (in the second patient) obliteration of the pre-existing mastoid cavity. One patient (first) suffered infection of mastoid cavity with extrusion of electrode, 55 months post-implantation. The infection could not be controlled without explantation, so the patient was explanted. The other (second) patient suffered facial nerve twitching, ear discharge and later failure of the implant as proved by integrity testing, 22 months post-implantation. The infection subsided after explantation. We recommend regular clinical and audiological follow-up of such patients in the same cochlear implantation center to avoid any complications which may lead to implant failure or electrode extrusion. This is also useful to discover and treat early any potential recurrent infection or cholesteatoma. High-resolution computed tomography scan of temporal bone is a good tool in the follow-up of patient with post-implantation complications or those implanted with closed blind sac technique which may be a better alternative technique than the open technique.

Delayed Electrode Extrusion after Cochlear Implant Repositioning

인공와우 이식이 양측성 심고도 감각신경성 난청의 안전하 고 효과적인 치료 방법이라는 의견은 이미 알려진 사실이다. 그럼에도 드물게는 이식된 장치가 피부를 뚫고 돌출하거나 장 치 주위에 감염이 발생하여 장치를 제거하거나 재이식 해야 하 는 심각한 부작용이 발생한다. 이전의 보고에 따르면 이러한 이유로 소아에서 인공와우 재이식률은 약 5.6~14%이고 성인 에서는 약 5.4~7.0%로 알려져 있다. 특히 소아에서 재이식의 빈도가 더 높은 이유는 두부손상 후 이식물이 피부 밖으로 돌 출하거나 이식물 감염을 일으키는 중이염의 발생률이 높기 때 문이다. 또 두개골의 성장과 같은 다양한 요인들로 인해 전극 위치이동의 위험도 더 높은 것으로 추정되고 있다. 최근에 는 수술 기술과, 이식 장치의 제조기술이 향상되어 재이식의 빈도는 점차 감소하고 있다. 그러나 아직까지도 장치 돌출이 나 감염으로 인하여 재이식을 시행해야 하는 경우가 드물지 않게 발생한다. 이식 장치가 피부 밖으로 돌출하거나 감염이 발생하는 경우 감염원, 감염의 정도, 생체막(biofilm) 존재의 가능성, 항생제 치료에 대한 반응에 따라 인공와우 장치를 제거, 혹은 장치를 그대로 둔 상태에서 감염 조직만 치료하는 방법을 선택할 수 있다. 기존 인공와우 장치를 유지하면서 감염 조직만 제거하 는 경우 수신기/자극기(receiver/stimulator)의 위치를 조금씩 조정할 수 있지만, 이때 와우 내에 삽입된 전극이 빠지거나 이 동하지 않도록 주의해야 한다. 일반적으로는 수신기/자극기와 와우내 전극 사이 거리가 멀고 전극 길이에 여유가 있기 때문 에 수신기/자극기의 위치가 조금 바뀌더라도 와우내 전극이 빠지는 경우는 발생하지 않는다. 그러나 수신기/자극기의 위치 가 많이 이동하거나, 위치 이동 후 전극에 인장력이 작용하는 경우 전극이 빠질 우려가 있다. 아직까지 위치를 얼마나 많이 Case Report Korean J Otorhinolaryngol-Head Neck Surg 2013;56:105-9 / pISSN 2092-5859 / eISSN 2092-6529 http://dx.doi.org/10.3342/kjorl-hns.2013.56.2.105

Microstructure of the Acid Welding Slag

Several E4303 type welding electrodes with different coating compositions were designed and manufactured using TL-25 welding electrode extrusion press. Welding slags of these electrodes were collected after welding on the low carbon steel, then the microstructure and the phase constitutes of the slags were investigated by optical microscope,scan electron microscope (SEM), electron probe microanalyzer (EPMA), Transmission electron microscope (TEM) and X-ray diffraction (XRD). It was indicated that the slags were mainly composed of amorphous matrix and Fe2MnTi3O10 crystal phase. Fe, Mn and Ti were the main elements to form the crystal phase, while Si, Al and Ca were mostly distributed in the amorphous matrix. The formation of the crystal phase in the slag could be controlled by adjusting the amount and the proportion of Fe, Mn and Ti in the welding rod coating.

Extracochlear electrode extrusion

Extracochlear electrode extrusion is a potentially under-recognized complication of cochlear implantation. As the age of implantation becomes younger, electrode extrusion is of concern due to future skull growth. Extrusion of several electrodes may compromise performance and thus require surgical reinsertion of the electrodes. Almost 60% of patients with electrode extrusion have required revision surgery.This paper presents a case report and literature review which discusses factors which contribute to electrode extrusion and emphasizes the need for a high degree of suspicion in certain situations. Surgical steps such as electrode fixation techniques are highlighted in order to attempt to reduce the occurrence of this complication.

Cochlear implantation surgery without posterior tympanotomy: Can we still improve it?

Conclusion: The amendments made to pre-existing transcanal approaches limit the possibility of extrusion of the electrode and reduce the time of ‘blind’ surgery. Objective: Alternative techniques to classic mastoidectomy and posterior tympanotomy for cochlear implantation have already been described but their main drawbacks result in either: (i) the risk of an electrode extrusion through the skin as the groove is drilled into the auditory canal or (ii) the risk of a facial nerve injury as the tunnel is drilled blindly into the posterior canal wall. The aim of this study was to describe and evaluate a new transcanal approach for cochlear implantation ruling out these difficulties. Patients and methods: Through a minimal retroauricular skin incision, a cochleostomy is performed directly via the auditory canal. The passage for the electrode is performed after drilling both a suprameatal hollow and a 1.5 mm hole into the superior-posterior canal wall, which opens the facial recess by an anterior approach. Thanks to this hole a transwall tunnel can afterwards be dug safely. Results: Twenty-three patients (8 adults, 15 children) were implanted without any difficulty. The mean follow-up was 22 months. No postoperative complication was observed.

The transmeatal approach: a new technique in cochlear and middle ear implants

The transmeatal approach (TMA) is a new approach for cochlear and middle-ear implantation. It is an open-tunnel technique that differs from closed transcanal non-mastoidectomy approaches. The TMA involves creating an open transcanal tunnel starting from the annulus superior to the chorda tympani laterally towards the suprameatal region. Then, through the open tunnel, a bony groove is created in the bone underneath the length of the external auditory canal (EAC) to protect the electrode from extrusion through the EAC. We report on the use of this approach in 131 patients (115 consecutive paediatric and 16 adult) between May 2004 and December 2007. During 2 to 46 months of follow-up there was no electrode extrusion.

The transmeatal approach: a new technique in cochlear and middle ear implants

The transmeatal approach (TMA) is a new approach for cochlear and middle-ear implantation. It is an open-tunnel technique that differs from closed transcanal non-mastoidectomy approaches. The TMA involves creating an open transcanal tunnel starting from the annulus superior to the chorda tympani laterally towards the suprameatal region. Then, through the open tunnel, a bony groove is created in the bone underneath the length of the external auditory canal (EAC) to protect the electrode from extrusion through the EAC. We report on the use of this approach in 131 patients (115 consecutive paediatric and 16 adult) between May 2004 and December 2007. During 2 to 46 months of follow-up there was no electrode extrusion. Copyright © 2009 John Wiley & Sons, Ltd.

Revision Cochlear Implantation Surgery in Adults

To assess the efficacy, risks, and indications of revision cochlear implantation (RCI) and to identify the clinical, audiologic, and device-related characteristics that predict outcome. Retrospective case series. Academic tertiary referral center. Adults (> or = 18 yr) who underwent RCI at Johns Hopkins University. Revision cochlear implant surgery. Speech perception by open-set testing and patient report and patient report of symptom resolution. During the 16-year period of this study, 4.8% of all adults implanted at our center have required 1 or more RCI surgeries. A total of 48 RCIs have been performed. The indications for RCI included infection (12%), electrode extrusion (15%), hard failure (23%), suspected device failure (42%), and isolated facial nerve stimulation (8%). Overall, successful resolution of the implant-related or medical condition was achieved with RCI in 83% of cases. Speech perception was lower in only 1 (2.1%) of 48 cases. Satisfactory preoperative speech recognition was preserved or surpassed in 5 of 6 infection cases and 8 cases with progressive symptoms of tinnitus and facial nerve stimulation. All cases of hard failure regained or surpassed previous peak performance. Improved speech recognition was experienced by 75% of cases with suspected device failure. Of cases in which RCI failed to restore previous functional benefit, there was a significant association with advanced age (> 70 yr). Whereas an abnormal integrity test was predictive of favorable outcome after RCI, a negative test was not predictive of outcome. A similar pattern of results was observed with respect to ex vivo device analysis. Revision cochlear implantation can be safely performed to restore lost benefit in appropriately selected cases. When properly performed after medical and audiologic options have been exhausted, RCI rarely compromises previous function and, in most cases, can resolve functional complaints and distracting symptoms. When positive, integrity testing is a useful screen for the presence of a device defect. In cases in which device integrity is uncertain, clinical judgment guided by longitudinal assessment can help determine whether RCI is likely to be beneficial.

Cold uniaxial compaction of Ti-containing powders: Rheological aspects

Pre-compaction of powder mixtures by cold pressing is being widely used in numerous areas of modern science and technology, including SHS. Normally, the process is being carried out at constant pressure ( P = const), so that the calibration plot in the coordinates pressure‐density (porosity) is obtained in a series of experiments at different P [1]. In this communication, we suggest to determine the calibration plot of a given press facility in one experimental run performed at a constant velocity of plunger feed V p . As a model, we used Ti + B and Ti + C + Ni powder mixtures. These mixtures were used as green mixtures in SHS extrusion of electrodes for electrospark alloying [2]. Powder compositions were as follows: 20 wt % Ti + 80 wt % B and 56 wt % Ti + 14 wt % C + 30 wt % Ni. Experiments were carried out in an INSTRON apparatus at constant V p (5 mm min ‐1 ) at a load up to 10 t (determined with an accuracy of 1%).