Silicone Allergy

3D Porous Binary Composites of Collagen, Elastin, and Fibrin Proteins Orchestrate Adipose Tissue Regeneration

The objective for this study is to advance the development of a specialized biomaterial that can effectively facilitate the regeneration of adipose tissue. In prior studies, the assessment of collagen (Col), elastin (Ela), and fibrin (Fib) unary scaffolds has been conducted. However, it is important to note that native adipose tissue is comprised of a diverse array of extracellular matrix (ECM) constituents. To mimic this behavior, binary compositions of collagen, elastin, and fibrin are fabricated in a 1:1 ratio, resulting in the formation of Col/Ela, Col/Fib, and Ela/Fib composites through a customized fabrication procedure. The physical properties of these scaffolds are comprehensively analyzed using a range of material characterization techniques. Additionally, the biological properties of the scaffolds are investigated by examining the survival, proliferation, and phenotype of adipose-derived stem cells. Subsequently, the aforementioned binary scaffolds are implanted into a rodent model for 28 days. the explants are analysed through X-ray microtomography, histology, and immunohistochemistry. The findings of the study demonstrate that the utilization of binary combinations of Col/Ela, Col/Fib, and Ela/Fib has a discernible impact on the physical and biological characteristics of the scaffolds. Nevertheless, Ela/Fib exhibits characteristics that make it a suitable candidate for adipogenesis due to its notable upregulation of caveolin-1 expression in both acellular and cellular cohorts. The combination of two natural polymers in this cell-material interaction has significantly enhanced the comprehension of adipogenesis.

[Cochlear implantation - Adverse effects on the cochlea and the vestibular organ]

Cochlear implantation is the treatment of choice for patients with profound hearing loss and deafness. At the same time, inserting a cochlear implant (CI) leaves damage to the inner ear. The preservation of inner ear structure and function has become a central issue in CI surgery. The reasons for this are i) electroacoustic stimulation (EAS), i.e., the option of joint stimulation by a hearing aid and a CI; ii) an improved audiologic outcome in electric-only stimulation; iii) the preservation of structures and residual hearing for potential future therapy options; and iv) the avoidance of side effects, such as vertigo. The exact mechanisms that determine the extent of damage to the inner ear and which factors contribute to preservation of residual hearing are not yet fully understood. In addition to the surgical technique, electrode selection may play a role. This article provides an overview of what is known about the direct and indirect adverse effects of cochlear implantation on the inner ear, of the methods available to monitor inner ear function during cochlear implantation, and of the focus of future research on preservation of inner ear structure and function.

Comparison of Adult and Pediatric Cochlear Implant Wound Complications: A Meta-Analysis

OBJECTIVE

To compare age-related differences in wound complications following cochlear implantation (CI).

METHODS

We performed a systematic review of PubMed, Cochrane Database, and Web of Science databases to identify original research evaluating the patient-level factors (demographics and medical history) associated with wound complications following CI. Outcomes were expressed as relative risk (RR) with 95% confidence intervals using the inverse variance method. Studies without comparison groups were described qualitatively.

RESULTS

Thirty-eight studies representing 21,838 cochlear implantations were included. The rate of wound complications ranges from 0% to 22%. Patient age (adult versus pediatric) was the only factor with comparison groups appropriate for meta-analysis. The 10 studies (n = 9547 CI's) included in the meta-analysis demonstrated that adults had a higher incidence of overall wound complications (2.94%) than in children (2.44%) (RR 1.31, 95% CI 1.01-1.69). Adults had a higher incidence of general/unclassified wound complications (2.07%) than in children (1.34%) (RR 1.68, 95% CI 1.12-2.52). There was no difference between adults and children for specific complications such as hematoma, infection, or seroma. Elderly patients (over age 75) have wound complication rates that range from 1% to 4%. No studies contained comparison groups regarding other patient-level factors and CI wound complications.

CONCLUSION

CI wound complication rates reported in the literature are low; however, adults have a higher risk of these complications than pediatric patients. The reported complication rate in elderly adults is low. There is a gap in CI research in consistently reporting wound complications and rigorous research investigating the impact of patient-level factors and wound complications.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:218-226, 2023.

Cochlear implantations in Jordan: Retrospective analysis of post-operative complications

AIMS

This study aims to carry out a retrospective analysis of demographic information and post-operative complications with special emphasis on complications related to the soft tissue over the implanted device in patients who underwent cochlear implantation.

SETTINGS AND DESIGN

Retrospective study.

PATIENTS AND METHODS

We conducted a retrospective review of 840 patients who had cochlear implants at our centre during the period between March 2010 and November 2020. The patients' demographic details and complications related to the soft tissue over the implanted device were analysed.

STATISTICAL ANALYSIS USED

SPSS software version 12.

RESULTS

In total, 380 (45.2%) patients were male and 460 (54.8%) were female. The age of patients at the time of surgery ranged between 7 months and 68 years and the mean age was 4.64 ± 2.91 years. The majority of patients underwent unilateral cochlear implantation (837 patients), with only three patients receiving a bilateral implant. There were a total of 19 implanted patients who developed complications related to the soft tissue around the implanted device, with an incidence rate of 2.3%. Haematoma was the most commonly encountered complication and other complications were: seroma, wound infection, abscess formation and flap necrosis.

CONCLUSIONS

Cochlear implantation is considered to be a reliable and safe surgical procedure for the rehabilitation of deaf patients. Complications can be avoided by proper patient preparation, appropriate incision and flap design, rigorous surgical techniques and periodic post-operative follow-up to detect and manage any complications early.

[Allergic reactions to bioimplants]

BACKGROUND

Bioimplants are used in a variety of ways in otorhinolaryngology, most commonly in facial reconstructive surgery, cochlear implants (CI), bone-anchored hearing aids, and partial/total ossicular replacement prostheses (PORP/TORP), but also for tympanic drainage, laryngeal cannula, voice prostheses after laryngectomy, etc., and in otorhinolaryngology-related procedures as dental implants in dentistry.

METHODS

A literature search was performed to analyze the immunology of allergic reactions to bioimplants and to determine the available evidence by searching Medline, PubMed, and national and international study and guideline registries and the Cochrane Library. Human studies published in the period up to and including 12/2021 were considered.

RESULTS

Based on the international literature and previous experience, a review of allergies to bioimplants in otolaryngology is presented.

CONCLUSION

Otorhinolaryngologists should always consider the possibility of allergic reactions when inserting allogeneic materials, particularly, but not only, when using bioimplants.

Autologous fat grafting as a minimally invasive technique to avoid cochlear implant extrusion

OBJECTIVES

Infection of the skin-muscle flap is one of the most severe risks of cochlear implantation. The aim of this paper is to describe a novel and minimally invasive procedure to avoid cochlear implant (CI) extrusion.

METHODS

A 79-year-old woman with severe comorbidities developed a pressure injury of the skin-muscle flap overlying the CI receiver/stimulator (R/S) nine years after surgery. Skin thinning and failure of conventional pressure injury management led the patient to a high risk of CI extrusion. Therefore, she underwent a single procedure of autologous fat grafting under local anesthesia to increase scalp thickness and vascularization over the CI R/S.

RESULTS

Within one month, complete healing of the pressure injury was observed, and the patient was able to safely use her CI. No further signs of infection and skin deterioration were detected at the 15-months follow-up.

DISCUSSION

Fat grafting has been proven to promote neoangiogenesis and tissue regeneration. To the best of our knowledge, this is the first report of fat grafting utilized in the skin-muscle flap area to avoid incipient CI R/S extrusion.

CONCLUSION

The described case demonstrates the efficacy of this salvage procedure to avoid major surgery and the additional costs related to CI reimplantation.

Management of delayed-onset skin flap complications after pediatric cochlear implantation

Purpose

To review delayed-onset skin flap complications associated with pediatric cochlear implantation (CI) in our institute, analyze the etiology, and explore effective treatment strategies.

Methods

Retrospective analyses of 811 children who had undergone cochlear implantation between January 2003 and March 2019 were performed. Twelve (1.48%) patients developed skin flap complications after CI. We present a classification of flap issues and wound histopathology following cochlear implantation. The interventions for flap problems included drug treatment, aspiration, local wound care, revision surgery, and explantation depending on the clinical situation. The temporalis myofascial reconstructive option is discussed.

Results

Seven subjects were cured with conservative treatment. Five cases with flap infection or necrosis underwent revision surgery, with wound closure in three cases (60%) and revision surgery with explantation in the remaining two cases (40%). Explantation ultimately led to wound healing in all cases. They all achieved excellent performance through re-implantation.

Conclusion

Flap complications after CI are rare but treatable. Comprehensive treatments should be developed to achieve a stable and healed wound for CI.

Hyperbaric oxygen therapy as a therapeutic option in cochlear implants extrusion treatment in infected wounds

Background: Cochlear implant extrusion as a result of infection is an uncommon, but serious complication, which can lead to implant removal as the ultimate solution.Objectives: (1) to identify the incidence of cochlear implant extrusion and its causes, (2) to report our management of patients presenting skin complications after cochlear implant surgery (3) to propose new therapeutical options with hyperbaric oxygen therapy (HBOT).Materials and methods: A retrospective analysis of medical documentation of 1250 patients who were operated on with cochlear implants in our department between 1993 and 2015. The medical charts of 25 patients were selected due to reported skin flap complications resulting in CI extrusion. Five of those patients were subsequently removed from the study because of no infection signs.Results: Non-traumatic cochlear implant extrusion occurred in 1.6% of implanted patients, and secondary treatment was effective in 90% of all cases (18 of 20 patients). HBOT as additional treatment was applied in 9 patients.Conclusions: Hyperbaric oxygen therapy can be considered as safe adjuvant treatment option in individual cases of proceeding with cochlear implant extrusion with signs of wound infection.Significance: HBOT may contribute to reducing the need for cochlear implant explantation due to infectious skin flap complication.

Microvascular free tissue transfer and cochlear implants: A case series and literature review

OBJECTIVE

The use of microvascular free tissue transfer (MVFTT) for defects of the scalp and lateral temporal bone in patients with cochlear implants (CI) is uncommon. Herein, we report our experience with the utility, indications, and outcomes for MVFTT in patients with cochlear implants.

METHODS

A retrospective review of patients at our institution from September 2016 to December 2017 identified subjects with coexistent cochlear implant and ipsilateral MVFTT of the lateral temporal bone or scalp. Information including demographics, indication for MVFTT, timing of CI and MVFTT, donor site, and previous radiation to the head and neck was collected. To assess the current literature on MVFTT in CI patients, a MEDLINE search was performed using key search terms.

RESULTS

Two patients with cochlear implants and MVFTT of the ipsilateral temporal bone or scalp were identified. One patient underwent MVFTT for advanced device extrusion with stable audiometric parameters rather than locoregional reconstruction or device explantation. The second patient had primary cochlear implantation at oncologic lateral temporal bone resection (LTBR) and MVFTT for locally advanced squamous cell carcinoma and concurrent profound sensorineural hearing loss (SNHL). A literature review identifies MVFTT as an option for advanced device extrusion, treatment of osteoradionecrosis, and reconstruction after primary oncologic surgery.

CONCLUSION

MVFTT is an important reconstructive tool for patients with functional, exposed cochlear implants. Cochlear implantation for severe to profound SNHL should be considered at the time of primary oncologic surgery and MVFTT of the lateral temporal bone or scalp.

LEVEL OF EVIDENCE

IV Laryngoscope, 130:1552-1557, 2020.

Cochlear Implant Surgery: How to Fix Receiver/Stimulator Avoiding Extrusion

Cochlear implant (CI) surgery is generally safe and associated with a limited number of complications, among which the extrusion of the receiver/stimulator (R/S) or the electrode misplacement and migration might require a CI re-implantation. The aim of this pilot study is to describe a new technique to firmly fix the R/S using the Mitek suture anchors system (Depuy Mitek Surgical Products, Inc. Raynham, Massachusetts). We tested two different models and in our experience, the web of suture created with this device can improve the stability of the bond of the R/S to the underlying curved bone surface. So, this system resulted in a less laborious manner keeping low the complication rate.

[The 'major' complications of cochlear implantation]

AIM

The objective of the present study was to improve the selected surgical stages of cochlear implantation (CIP) taking into consideration the results of the analysis of the outcomes of re-operations.

MATERIAL AND METHODS

A total of 53 patients (4 adults and 49 children) were referred to our clinic for re-operations deemed to be required for the management the major complications following CI during the period from 2014 to 2017. Primary cochlear implantation was performed in other clinics. Re-operations were carried out at different time intervals after the primary surgical intervention under the guidance of a single experienced surgeon.

RESULTS

The technical malfunction of the inner part of the implant prevailed among the causes behind the major complications of CI. It accounted for 47% of the total number of complications and required the replacement of the device. The next most frequent form of the complications (that accounted for 15% of all the cases) was the introduction of an active electrode into the cells of hypotympanum. The remaining complications occurred only in isolated cases. The detailed analysis of all the revealed complications was undertaken with the description of their causes and variants and the surgical strategy chosen for the management of each concrete patient. The decision about the necessity of either the removal or the substitution of the implant was taken on an individual basis. The successful outcome of the surgical treatment of all the operated patients with the major complications of cochlear implantation was achieved.

CONCLUSION

The frequency and severity of the major complications of cochlear implantation are directly dependent on the patient's anatomical features, surgeon's qualifications, the quality of the implants, and lifestyle factors (e.g. head trauma, etc.). Cochlear implantation continues to be the only method for hearing rehabilitation in the patients suffering from severe sensorineural impairment of hearing. In the cases of cochlear implantation with the prospects of delayed re-implantation, leaving the active electrode in the scala tympani of the cochlea is a necessary measure to prevent synechiae.

[The complications of cochlear implantation and the methods for their treatment]

The objective of the present study was to improve the surgical component of cochlear implantation (CI) with special reference to the prevention and correction of its complications. A total of 967 cochlear implantation were performed on 847 patient treated based at the A. Geidarov Republican Hospital, Ministry of Internal Affairs of Azerbaijan, and the Research and Clinical Centre of Otorhinolaryngology, FMBA of Russia during the period from 2014 till 2017. The majority of the patients (n=540) were the children at the age varying from 1 to 4 years. All surgical interventions were carried out under the supervision of a single experienced specialist. The check-up examinations were performed every three months during the postoperative period. The postoperative complications were categorized in terms of severity (as major and minor) and time of the first manifestation (intraoperative and delayed). The detailed analysis of all documented complications was performed including the description of their variants and causes as well as of the surgical strategy applied in each concrete case. The frequency of major and minor complications was estimated at 2.6 and 1.6% respectively. It is concluded that cochlear implantation performed by an experienced surgeon provides a relatively safe method for the treatment of the patients in the clinics with a low frequency of complications of such interventions. The most common cause of the major complications of cochlear implantation is the technical defect of the implants the frequency of which amounted to 68% in the present study.

Foreign Body Response to Silicone in Cochlear Implant Electrodes in the Human

HYPOTHESIS

Silicone as part of a cochlear implant electrode may be responsible for a foreign body response in the human.

BACKGROUND

Clinical evidence of a foreign body response to a cochlear implant has been reported. In a previous study, particulate material found within the fibrous sheath and within macrophages surrounding a cochlear implant has been identified as being consistent with platinum. However, to date, there has been no histologic evidence of a role for silicone in this cellular immune response.

METHODS

A total of 44 temporal bone specimens from 36 patients were reviewed by light microscopy for evidence of presumed platinum and/or silicone foreign bodies in an extracellular or intracellular location. Identification of cell type involved in phagocytosis of foreign body material was accomplished using CD163 immunostaining. The identity and source of the foreign body material was confirmed using energy-dispersive X-ray spectroscopy and scanning electron microscopy.

RESULTS

Evidence for both platinum and silicone was found in all 44 specimens. In three patients, anti-CD 163 immunostaining demonstrated phagocytized platinum and silicone foreign bodies. In five specimens, energy-dispersive X-ray spectroscopy demonstrated that the birefringent foreign bodies were consistent with silicone. Scanning electron microscopy of two electrodes removed from temporal bones demonstrated small cracks, fragmentation, and small circular defects in the silicone carrier.

CONCLUSION

Histologic evidence of a foreign body response to the presence of platinum and silicone in a cochlear implant has been demonstrated and may be responsible for some reported delayed failures or extrusion.

The pattern and degree of capsular fibrous sheaths surrounding cochlear electrode arrays

An inflammatory tissue reaction around the electrode array of a cochlear implant (CI) is common, in particular at the electrode insertion region (cochleostomy) where mechanical trauma often occurs. However, the factors determining the amount and causes of fibrous reaction surrounding the stimulating electrode, especially medially near the perimodiolar location, are unclear. Temporal bone (TB) specimens from patients who had undergone cochlear implantation during life with either Advanced Bionics (AB) Clarion ™ or HiRes90K™ (Sylmar, CA, USA) devices that have a half-band and a pre-curved electrode, or Cochlear ™ Nucleus (Sydney, Australia) device that have a full-band and a straight electrode were evaluated. The thickness of the fibrous tissue surrounding the electrode array of both types of CI devices at both the lower (LB) and upper (UB) basal turns of the cochlea was quantified at three locations: the medial, inferior, and superior aspects of the sheath. Fracture of the osseous spiral lamina and/or marked displacement of the basilar membrane were interpreted as evidence of intracochlear trauma. In addition, post-operative word recognition scores, duration of implantation, and post-operative programming data were evaluated. Seven TBs from six patients implanted with AB devices and five TBs from five patients implanted with Nucleus devices were included. A fibrous capsule around the stimulating electrode array was present in all twelve specimens. TBs implanted with AB device had a significantly thicker fibrous capsule at the medial aspect than at the inferior or superior aspects at both locations (LB and UB) of the cochlea (Wilcoxon signed-ranks test, p < 0.01). TBs implanted with a Nucleus device had no difference in the thickness of the fibrous capsule surrounding the track of the electrode array (Wilcoxon signed-ranks test, p > 0.05). Nine of fourteen (64%) basal turns of the cochlea (LB and UB of seven TBs) implanted with AB devices demonstrated intracochlear trauma compared to two of ten (20%) basal turns of the cochlea (LB and UB of five TBs) with Nucleus devices, (Fisher exact test, p < 0.05). There was no significant correlation between the thickness of the fibrous tissue and the duration of implantation or the word recognition scores (Spearman rho, p = 0.06, p = 0.4 respectively). Our outcomes demonstrated the development of a robust fibrous tissue sheath medially closest to the site of electric stimulation in cases implanted with the AB device electrode, but not in cases implanted with the Nucleus device. The cause of the asymmetric fibrous sheath may be multifactorial including insertional trauma, a foreign body response, and/or asymmetric current flow.

After cochlear implantation: Complications related to flap around implants

Objective

To report complications related to flap around implants after cochlear implantation, possible causes of such complications and treatments.

Methods and material

We performed a retrospective analysis of children in whom complications related to flap around implants occurred after undergoing cochlear implantation in our department from 2005 to 2016.

Results

Complications among 1500 cochlear implantation (CI) recipients by the same surgeon included hematoma (n = 20) and seroma around implants (n = 15), of which most (n = 10) recovered in 2 weeks after effective drainage, utility of antibiotics and pressure dressing, but 5 developed flap necrosis and had to undergo contralateral re-implantation. Four patients developed abscess around implants, of whom 2 recovered after 2 weeks of drainage, gentamicin irrigation and use of antibiotics, but 2 patients ended up with flap necrosis and had to receive contralateral reimplantation.

Conclusions

Immediate drainage, pressure dressing and antibiotics can be used to effectively control seroma around implants. For seroma lasting for more than two weeks without improvement, surgical drainage may be need.

Histopathological Effects of Parylene C (poly-chloro-p-xylylene) in the Inner Ear

Objective

To assess the histopathological effects of parylene C (PC) (poly-chloro-p-xylylene) in the inner ear.

Methods

Nine adult Dunkin Hartley guinea pigs (500-600 g) were included in the study. PC pieces were inserted into the cochlea in the right ear of the animals (study group). The round windows were punctured in the left ears comprised the control group. After three months, the animals were sacrificed, and the dissected temporal bones were examined under a light microscope.

Results

No significant difference was revealed between the study and control groups regarding histopathological findings such as perineural congestion, perineural inflammation, neural fibrosis, number of ganglion cells, edema, and degeneration of ganglion cells (p>0.05).

Conclusion

PC did not cause any additional histopathologic damage in the cochlea. This finding may be promising regarding the use of PC in cochlear implant electrodes as an alternative to silicon materials in the future.

Intracochlear inflammatory response to cochlear implant electrodes in humans

HYPOTHESIS

This study evaluates the types and degrees of tissue response adjacent to the electrode of multichannel cochlear implants.

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Cellular immunologic responses to cochlear implantation in the human

A cochlear implant array consists of biomaterials, including metal and polymeric in type which are biocompatible, but not necessarily bio-inert. Histologic evidence of a foreign body reaction has been described in temporal bones in patients who in life had undergone cochlear implantation. In the current study, the cellular immune response was characterized using immunohistochemical stains for B-cell lymphocytes (CD20), T-cell lymphocytes (CD3), and macrophages (CD68). In addition, energy dispersive spectroscopy by scanning electron microscopy (EDS-SEM) was performed to characterize the nature of particulate foreign material seen near the electrode array. Infiltrations of B-cell and Tcell lymphocytes and macrophages were identified immunohistochemically. The track of the electrode array was frequently lined by multi-nucleated foreign body giant cells. Energy dispersive X-ray spectroscopy identified the particulate material found in the fibrous sheeth surrounding the cochlear implant to be consistent with platinum. In conclusion, a cochlear implant generates a vigorous cellular immune response consisting of B and T lymphocytes, foreign body giant cells, and macrophages. Platinum was identified as one of the antigens likely responsible for this cellular response. This foreign body response may in certain cases result in migration or even extrusion of an implant device.

Artificial neural networks for bilateral prediction of formulation parameters and drug release profiles from cochlear implant coatings fabricated as porous monolithic devices based on silicone rubber

Objectives

The coating of cochlear implants for topical delivery of drugs, for example, corticosteroids, or antibiotics is a novel approach to manage post-surgical complications associated with cochlear implantation surgery like inflammation or infections. Many variables, including formulation parameters, can be changed to modulate the amount and duration of drug release from these devices. Mathematical modeling of drug release profile from a delivery system may be helpful to accelerate formulations in a more cost-efficient way. To attain specific in vitro drug release characteristics, a model should be capable to provide good estimates on the initial formulation parameters, for example, composition, geometry and drug loading vice versa. Here, artificial neural networks (ANNs) are used to predict dexamethasone (DEX) release profile and formulation parameters, bilaterally, from cochlear implant coatings designed as porous, monolithic silicone rubber-based matrices.

Methods

The devices were fabricated as monolithic dispersions of DEX in a silicone rubber matrix containing porogens. A newly developed mathematical function was fitted on the experimental DEX release curves, and the function coefficients were fed into the network as input variables to simulate drug release profile from the porous devices. Formulation variables consisted of drug loading percentage (0.05–0.5% w/w), porogen type (dextran (dext) or sodium chloride particles) and porogen content (5–40% w/w). The ANN was also examined to determine optimal levels of the formulation parameters to provide a specifically desired drug release profile.

Key findings

The results showed that DEX release profile from porous cochlear implant devices can be modelled accurately and precisely using ANN in order to predict optimal levels for the formulation parameters to provide a specific drug release profile vice versa.

Conclusions

The developed ANNs were used to achieve shorter formulation development process, and to provide tailor-made drug delivery regimens. ANNs were also successfully simulated non-linear relationships present between the initial formulation variable(s) and predict the subsequent drug release patterns.

Surgery of the ear and the lateral skull base: pitfalls and complications

Surgery of the ear and the lateral skull base is a fascinating, yet challenging field in otorhinolaryngology. A thorough knowledge of the associated complications and pitfalls is indispensable for the surgeon, not only to provide the best possible care to his patients, but also to further improve his surgical skills. Following a summary about general aspects in pre-, intra-and postoperative care of patients with disorders of the ear/lateral skull base, this article covers the most common pitfalls and complications in stapes surgery, cochlear implantation and surgery of vestibular schwannomas and jugulotympanal paragangliomas. Based on these exemplary procedures, basic "dos and don'ts" of skull base surgery are explained, which the reader can easily transfer to other disorders. Special emphasis is laid on functional aspects, such as hearing, balance and facial nerve function. Furthermore, the topics of infection, bleeding, skull base defects, quality of life and indication for revision surgery are discussed. An open communication about complications and pitfalls in ear/lateral skull base surgery among surgeons is a prerequisite for the further advancement of this fascinating field in ENT surgery. This article is meant to be a contribution to this process.

Endocochlear inflammation in cochlear implant users: case report and literature review

OBJECTIVES

Cochlear implantation is a relatively safe procedure with a low complication rate. The overall rate of complications among cochlear implant patients ranges from 6% to 20%. Major complications are those that are life-threatening or require surgery, whereas minor complications are those that can be medically treated. Nonetheless, certain complications, even if highly rare, may require specific investigations and treatments. Among these rare complications are those with endocochlear involvement, such as cochleitis or labyrinthitis, with fibrosis or ossification that could lead to explantation. The aims of the present study were to report a particular case of post-operative cochleitis and to review the rate of complications after cochlear implantation, emphasising those conditions with proven endocochlear involvement.

METHODS

We refer to the case of an eight-year-old Italian boy affected by the sudden onset of headache, ipsilateral otalgia and facial paresis, who presented to our clinic for inexplicable worsening of the performance of his implant and his residual hearing, six years after surgery. A complete investigation including (clinical history, routine, autoimmune and serological blood tests, electrophysiological measurements from the cochlear implant and neuroimaging) was performed and is herein described. Additionally, a comprehensive review of the literature was conducted using internet search engines; 274 papers were selected, 88 of which were best suited to our purposes.

RESULTS

In our case, the progression of the symptoms and the performance decrement required explantation, followed by a complete recovery. Reviewing the literature revealed only three reports concerning cases of proven endocochlear phlogosis that required revision surgery. Wound swelling/infection and vertigo remain the two most common complications of cochlear implantation. Failure of the device is the third most frequent complication (10.06% of all complications and 1.53% of cochlear implantations). Other rare conditions (such as granulating labyrinthitis with cochlear fibrosis, ossification and erosion, silicone allergy and the formation of a biofilm around the internal device) are possible and unpredictable. Although rare (approximately 1%), such cases may require explantation.

CONCLUSIONS

Despite efforts by both surgeons and manufacturers, device-related and surgical complications still occur. These and other rare conditions demand specific management, and their frequency may be underestimated. Further studies are needed to assess more realistic rates of complications and devise more efficient strategies for early diagnosis and treatment.

Revision cochlear implantation in children

Revision cochlear implant (RCI) surgery has become an important tool for the management of cochlear implantation complications. This review encompasses both common and uncommon indications of RCI, diagnostic and management considerations, outcomes, surgical principles, and emerging applications. In summary, early identification of complications and suboptimal device performance is imperative for children who are in critical periods of communicative development. Independent of indications, most RCI achieve a successful restoration of sound. Although rare, it is prudent to discuss the potential complications of revision surgery and their implications with patients and their families.

Foreign body reaction after cochlear implantation

Cochlear implantation is a widely accepted, safe procedure for patients with severe to profound sensorineuronal hearing loss. While complications are rare, revision surgeries are required for complications like device failure, misplaced electrode, flap necrosis, and wound infection. Foreign body reaction is a rare complication following cochlear implantation. We experienced a case of foreign body reaction after cochlear implantation treated by device removal. Foreign body reaction has to be considered as one of several causes in cochlear implantation cases that show symptoms mimicking recurrent wound infection or delayed extrusion. We report a case of foreign body reaction with a literature review.

[Clinical outcomes cochlear reimplantation]

To clarify the clinical features of cochlear reimplantation and surgical changes in auditory performance, we retrospectively reviewed 10 of 252 cochlear implantation surgeries-6 adults and 4 children-among 129 children and 123 adults done between April 1987 and May 2009. Mean duration from initial implantation to reimplantation was 50.3 months in children and 89 months in adults, most commonly due to hard failure and implant exposure/infection (33%) in children and to hard failure (75%) in adults. The initial device implanted was the Nucleus multichannel implant (CI22M, CI24M, or CI24R). The second implant in 7 was the same or an upgrade of the same manufacturer's device, and in 2 children the HiRes 90K (Hifocus 1j) and in 1 adult the Clarion 1.2. Full initial and reinsertion succeeded in 8 cases but reinsertion proved difficult in 2 due to severe intracochlear granulation and osteoneogenseis. Auditory performance analyzed in 7 cases was mostly equal to or better than before reimplantation, although differences were not statistically significant. Reinsertion is rarely difficult, but electrode choice is important in preparing for difficult reinsertion. Post reinsertion auditory performance is satisfactory with some exceptions.

Biomaterials in cochlear implants

The cochlear implant (CI) represents, for almost 25 years now, the gold standard in the treatment of children born deaf and for postlingually deafened adults. These devices thus constitute the greatest success story in the field of ‘neurobionic’ prostheses. Their (now routine) fitting in adults, and especially in young children and even babies, places exacting demands on these implants, particularly with regard to the biocompatibility of a CI’s surface components. Furthermore, certain parts of the implant face considerable mechanical challenges, such as the need for the electrode array to be flexible and resistant to breakage, and for the implant casing to be able to withstand external forces.

As these implants are in the immediate vicinity of the middle-ear mucosa and of the junction to the perilymph of the cochlea, the risk exists – at least in principle – that bacteria may spread along the electrode array into the cochlea. The wide-ranging requirements made of the CI in terms of biocompatibility and the electrode mechanism mean that there is still further scope – despite the fact that CIs are already technically highly sophisticated – for ongoing improvements to the properties of these implants and their constituent materials, thus enhancing the effectiveness of these devices.

This paper will therefore discuss fundamental material aspects of CIs as well as the potential for their future development.

[Study of a case of cochlear implant with recurrent cutaneous extrusion]

OBJECTIVE

An observation of a difficult-to-diagnose complication of the cochlear implant: recurring cutaneous extrusion of a cochlear implant is reported.

PATIENTS AND METHODS

The history of an adult patient with total deafness is reported. She received an implant in her right ear in 1988, which was then explanted because of absence of hearing results. She received a second implant in her left ear in 2002, which was then explanted in 2007 because of cutaneous extrusion. In 2008, a second implant of a different brand was placed in her left ear, with the central part placed away from the first site, but extrusion recurred. A new attempt to encapsulate the central part with a hydroxyapatite box also ended in extrusion and was explanted in 2008.

RESULTS

Various diagnoses to explain these cutaneous problems were suggested during this clinical progression: infection, allergy, and a reaction to a foreign body. No hypothesis could be clearly ruled out.

CONCLUSION

Cutaneous complications after cochlear implant are exceptional. As soon as cutaneous disorders appear, a rigorous diagnostic process must be followed so that the patient can be recommended a long-lasting solution to restore quality hearing.

Factors affecting choice of device by cochlear implant candidates

OBJECTIVE

To investigate the ways the various cochlear devices are chosen by candidates/surrogates and analyze the factors that influenced their decisions.

SETTING

University-affiliated tertiary referral center.

METHOD

: A questionnaire that included general items and questions on device's aesthetics, technical considerations, and quality was sent to 429 patients who underwent cochlear implantation between June 1997 and December 2006 in our department.

RESULTS

One hundred eighty-four questionnaires were returned, yielding a response rate of 42.9%. Some patients did not receive the questionnaires because of the postal address changes. In addition, recently implanted patients/their surrogates were more ready to answer on the questionnaire on decision-making process compared with those who received their devices before 2001. The Nucleus users were more influenced by the questions pertaining to the quality/reliability of the device than the aesthetic and technical aspects. The ABC users were more influenced by the aesthetic aspects, and the MED-EL users were generally influenced by all the groups of questions equally. Females used the Internet as the source of information on the devices significantly more than males, and their decisions were more influenced by their families than those of the males. In addition, the females were more influenced by the quality of a device's function compared with males. Pediatric candidates (aged 1-16 yr) were significantly more influenced by the experience of other implant users, the medical staff, and religious considerations than adults. Adults arrived at decisions more easily than children or their surrogates. The adults and older children were more influenced by the ease of the device's functioning compared with the young children.

CONCLUSION

Choosing the type of cochlear implant device is a highly individualized process that depends on various personal, social and cultural factors, and factors linked directly to the device itself.

Foreign body or hypersensitivity granuloma of the inner ear after cochlear implantation: one possible cause of a soft failure?

HYPOTHESIS

A tissue response in the form of foreign body or a hypersensitivity reaction to cochlear implantation is common and may be one possible cause of a soft failure of cochlear implantation.

BACKGROUND

After a successful cochlear implantation, delayed failure may occur. The causes of a "soft" failure, that is, one in which device malfunction cannot be proven, are unknown.

METHODS

The histopathology of the temporal bones of a patient who, in life, had experienced a soft failure after cochlear implantation was described. In addition, the temporal bones of 8 other subjects who, in life, had undergone cochlear implantation were studied for evidence of a foreign body or hypersensitivity reaction.

RESULTS

In the case report, a necrotizing granulomatous giant cell reaction surrounded the cochlear implant electrode track through the mastoid and the middle ear and into the cochlea in both ears. There was osteolysis of the cribrose area, otic capsule, and bone between the facial nerve and the cochlea and destruction of the organ of Corti and spiral ganglion. In the additional 8 cases studied, a similar, although less pronounced, foreign body or hypersensitivity reaction was seen in 6 (75%) of the cases.

CONCLUSION

A foreign body or hypersensitivity reaction in the form of giant cells and lymphocytic cell infiltration is common after cochlear implantation and may be one possible cause of soft failure.