Frequency of electrode migration after cochlear implantation in the early postoperative period. What are associated risk factors?

OBJECTIVES: To estimate the prevalence of, and risk factors associated with electrode migration (EM) in cochlear implant (CI) recipients. DESIGN: Historical cohort study of all CIs performed between 1 January 2018 and 1 August 2021 in a single tertiary adult and paediatric CI centre in the UK. MAIN OUTCOME MEASURES: The primary aim is to determine the prevalence of electrode migration, comparing intraoperative surgeon report and examination of a routine plain radiograph performed 2 weeks after surgery. EM is defined as the detection of movement of two or more electrodes out of the cochlea from the time of surgery. Multivariate analysis was performed to investigate preoperative and intraoperative risk factors that might predispose to migration. RESULTS: Four hundred and sixty-five patients, having 516 distinct surgeries, with 628 implants were analysed. EM occurred following 11.5% of implant operations. Pre-existing cochlear abnormality was an independent associated risk factor for EM (OR: 3.40 ⟨1.20-9.62⟩ p = .021). Demographics, surgical technique, usage of a precurved electrode, CSF leak, surgeon seniority and intraoperative telemetry did not influence risk of migration. There were 5 implants (0.8%) which migrated later than 2 weeks, with a median date of imaging diagnosis (x-ray or CT scan) of 263 days ⟨IQR:198⟩, for which head injury was a common precipitating factor. There were differences in the risk of migration between different lateral wall electrodes. CONCLUSION: EM in the early postoperative period is a common occurrence and is more likely in implant recipients with obstructed or malformed cochleae.

Detecting and managing partial shorts in Cochlear implants: A validation of scalp surface potential testing.

OBJECTIVE: To investigate the value of scalp surface potentials to identify and manage partial short circuits to ground in cochlear implant electrodes. DESIGN: A retrospective review of patients with suspected partial short circuits. MAIN OUTCOME MEASURE: Electrical output of individual electrodes was measured using scalp surface potentials for patients reporting a change in hearing function. Electrical output was compared to functional performance and impedance measurements to determine if devices with suspected partial short circuits were experiencing a decrease in performance as a result of reduced electrical output. Electrical output was checked in an artificial cochlea for two implants following explant surgery to confirm scalp surface potential results. RESULTS: All patients with suspected partial short circuits (n = 49) had reduced electrical output, a drop in impedances to approximately ½ of previously stable measurements or to below 2 kΩ, an atypical electrical field measurement (EFI) and a decline in hearing function. Only devices with an atypical EFI showed reduced electrical output. Results of scalp based surface potentials could be replicated in an artificial cochlea following explantation of the device. All explant reports received to date (n = 42) have confirmed partial short circuits, with an additional four devices failing integrity tests. CONCLUSION: Surface potential measurements can detect partial shorts and had 100% correlation with atypical EFI measurements, which are characteristic of a partial short to ground in this device. Surface potentials can help determine the degree to which the electrode array is affected, particularly when behavioural testing is limited or not possible.

Cochlear Implantation in Elderly Patients: Survival Duration, Hearing Outcomes, Complication Rates, and Cost Utility.

INTRODUCTION: The prevalence of hearing loss and its consequences is increasing as the elderly population grows. As the guidelines for cochlear implantation (CI) expand, the number of elderly CI recipients is also increasing. We report complication rates, survival duration, and audiological outcomes for CI recipients aged 80 years and over and discuss the cost utility of CI in this age group. METHODS: A retrospective cohort study was undertaken of all CI recipients (126 cases), aged 80 years and over at the time of their surgery, implanted at our institution (Cambridge University Hospitals) during a period from January 1, 2001, to March 31, 2019. Data on survival at 1, 3, and 5 years post-implantation, post-operative complications and functional hearing outcomes including audiometric and speech discrimination outcomes (Bamford-Kowal-Bench sentence test) have been reported. RESULTS: The mean age at implantation was 84 years. The mean audiometric score improved from 108 dB HL to 28 dB HL post-implantation. The mean Bamford-Kowal-Bench score improved from 14% to 66% and 73% at 2 and 12 months post-implantation, respectively. The complication rate was 15.3%. The survival probability at 1 year post-implantation was 0.95 for females and 0.93 for males, at 3 years was 0.89 for females and 0.81 for males, and at 5 years was 0.74 for females and 0.54 for males. CONCLUSION: CI is safe and well-tolerated in this age group and elderly patients gain similar audiometric and functional benefit as found for younger age groups.

Cochlear Implantation in NF2 Patients Without Intracochlear Schwannoma Removal.

OBJECTIVE: To determine if cochlear implantation without removal of inner ear schwannomas (IES) is an effective treatment option for Neurofibromatosis 2 (NF2) patients. To determine how the presence of an intracochlear schwannoma might impact cochlear implant (CI) outcomes and programming parameters. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary center for cochlear and auditory brainstem implantation. PATIENTS: Of 10 NF2 patients with IES, 8 are reported with no previous tumor removal on the implanted ear. INTERVENTIONS: Cochlear implant without tumor removal. MAIN OUTCOME MEASURES: Performance outcomes with CI at least 1-year post intervention. Programming parameters, including impedances, for patients with IES. RESULTS: All patients had full insertion of the electrode arrays with round window approaches. Performance outcomes ranged from 0 to 100% for Bamford-Kowal-Bench sentences. Impedance measurements for active electrodes for patients with IES were comparable to those measured in patients without vestibular schwannoma (VS). Only patients who had radiation treatment before receiving their implant had elevated threshold requirements for CI programming compared with CI recipients without VS. CONCLUSION: Cochlear implantation without tumor removal is an effective option for treating NF2 patients with IES. The presence of an intracochlear tumor did not have an impact on CI performance or programming requirements compared with patients without VS; however, previous treatment with radiation may be related to elevated current requirements in the CI settings.

Correction to: Multiple spontaneous skull base cerebrospinal fluid leaks: some insights from an international retrospective collaborative study.

In the original publication of the article, the following affiliation "Medical school, University of Nicosia, Nicosia, Cyprus" of the author "Christos Georgalas" was missed and included in this correction.

Multiple spontaneous skull base cerebrospinal fluid leaks: some insights from an international retrospective collaborative study.

PURPOSE: Spontaneous skull base cerebrospinal fluid leaks occurring without any apparent cause are rare. But those patients that present such leaks simultaneously, or successively, in multiple locations are even rarer. Given the rarity of this condition, we collected data from other groups in a multicentre study to reach an adequate number of patients and draw some preliminary considerations. METHODS: We carried out a multicentre retrospective study on a cohort of patients treated at third level hospitals in Italy, Spain, United Kingdom and Greece for multiple spontaneous-CSF leaks and we compared them with a control group of patients treated for recurrent spontaneous-CSF leaks. Data regarding clinical aspects, radiological findings, surgical techniques and outcome were collected and preliminary considerations on the results were discussed. RESULTS: A total of 25 patients presented multiple simultaneous spontaneous CSF leaks while 18 patients fit with the criteria of recurrent spontaneous CSF leaks. Data analysis was conducted separately. CONCLUSIONS: Our understanding of the pathogenesis of this condition is currently very limited. A causative role of IIH may be present but the differences that emerged from the comparison with patients with recurrent fistulas seem to promote the possible role of other cofactors. A longer follow-up period is needed, and, in our opinion, prospective and multicentre studies are the only solution to seriously deal with such a complex topic.

Performing MRI Scans on Cochlear Implant and Auditory Brainstem Implant Recipients: Review of 14.5 Years Experience.

OBJECTIVE: To assess the complication rate of magnetic resonance imaging (MRI) using 1.5 T scanners on cochlear implant (CI) and auditory brainstem implant (ABI) recipients over 14.5 years. METHODS: Prospective study conducted in a tertiary referral center for cochlear and auditory brainstem implantation, including patients with neurofibromatosis 2. The primary outcome was complications related to MRI scanning in implant recipients, including failure to complete MRI sessions. The secondary outcome was magnet void size due to MRI scanning with magnet in situ. RESULTS: Ninety-seven patients (21 ABI recipients, 76 CI recipients of whom 23 were bilateral) underwent a total of 428 MRI sessions consisting of 680 MRI procedures, which generated 2,601 MRI sequences (excluding localizers). Of these, 28/428 (6.5%) MRI sessions were performed with magnet removed, and the remaining 400/428 (93.4%) with the magnet in situ. The overall complication rate per session was 15/428 (3.5%). The majority of complications were accounted for by patient discomfort, in some cases requiring abandoning the scan session, but 5 magnet dislocations were also recorded. There were no cases of implant device failure or excessive demagnetization of the receiver stimulator magnet.For CI and ABI recipients, the implant caused large voids of around 110 mm × 60 mm with the magnet in situ which reduced to 60 mm × 30 mm when the magnet was removed. However, it was usually possible to visualize the internal acoustic meatus and cerebellopontine angle by positioning the implant package higher and further forward compared with conventional positioning. CONCLUSION: MRI scanning in ABI and CI recipients is generally safe and well tolerated without magnet removal, and carries a low rate of complications. However, patients should be fully informed of the possibility of discomfort, and precautions such as local anesthetic injection and head bandaging may reduce the likelihood of adverse events.

Hearing rehabilitation outcomes in cochlear implant recipients with vestibular schwannoma in observation or radiotherapy groups: A systematic review.

Objectives: Vestibular schwannomas (VS) are rare benign tumours of the vestibular nerve that cause hearing loss. Management strategies include watchful waiting, radiotherapy or surgical resection. Historically, the presence of retrocochlear disease has been considered to be a contra-indication to cochlear implantation (CI). The aim of this systematic review is to assess hearing rehabilitation outcomes for CI recipients with VS, either sporadic or associated with neurofibromatosis type 2, whose tumours have been managed with either observation or radiotherapy.Methods: PubMed, Embase, and Cochrane Library databases were searched from inception through to November 2018. 50 cases from 12 studies met the inclusion criteria. Patient demographics, VS characteristics, management strategy, pre-CI hearing status, electrical promontory stimulation testing, post-CI hearing status and speech perception scores, functional benefits and follow-up length are reported.Results: Radiotherapy and observation groups had similar patient demographics in terms of age at CI, tumour size and duration of deafness. Following CI, 64% and 60% of patients in the radiotherapy and observation groups achieved open-set speech perception, respectively. Pure tone average thresholds (33 vs. 39 dB) and speech scores were also comparable between both groups.Conclusion: Ipsilateral CI in patients with VS that have not been surgically resected can provide beneficial hearing rehabilitation outcomes.

A systematic review on prevention and management of wound infections from cochlear implantation.

OBJECTIVE OF REVIEW: Surgical site infections are a recognised complication of cochlear implant (CI) surgery with significant morbidity. Our aim was to search for the optimum prevention and management strategy to deal with this issue. TYPE OF REVIEW: Systematic review. SEARCH STRATEGY: A systematic literature search was undertaken from the databases of Embase, CINAHL, MEDLINE® , Web of Science, Scopus and Cochrane Library according to the predefined inclusion and exclusion criteria. EVALUATION METHOD: All relevant titles, abstracts and full-text articles were reviewed by two authors who resolved any differences by discussion and consultation with senior authors. RESULTS: Fourteen articles were included in our review. The overall quality of evidence was low with the vast majority of the studies being retrospective case series and expert opinions. No randomised controlled trials were noted. We found consistent reports that intraoperative prophylactic antibiotics should be given to all patients undergoing CI and that the vast majority of CI wound infections had grown Staphylococcal spp. or Pseudomonas spp. CONCLUSION: Our review has not identified any reliable or reproducible strategies to prevent and deal with wound infections after CI. We strongly encourage further research within this field and would suggest that a consensus of opinions from a multidisciplinary panel of experts may be a pragmatic way forward as an effective guide.

MRI without magnet removal in neurofibromatosis type 2 patients with cochlear and auditory brainstem implants.

OBJECTIVE: To assess the impact on image quality of MRI without magnet removal in cochlear implant (CI) and auditory brainstem implant (ABI) users with neurofibromatosis type 2 (NF2). STUDY DESIGN: Prospective cohort. SETTING: Tertiary center for cochlear and auditory brainstem implantation. PATIENTS: Thirteen patients (10 ABI, 3CI) with NF2 underwent a total of 76 MRI scans. INTERVENTIONS: MRI without magnet removal. MAIN OUTCOME MEASURE: Ability to visualize the ipsilateral and contralateral cerebellopontine angles (CPAs) and internal auditory meati (IAM) with head MRI. RESULTS: Of the 76 scans, 40 were of the head, 28 of the spine and 8 of other regions. Scanning was performed with a tight head bandage and plastic card. There were no cases of altered implant function or demagnetization of the device magnet.A grading system was used to assess the view of the ipsilateral IAM-CPA. In 85% of head scans, the view was unimpaired (Grade 0). In 13%, there was distortion (Grade 1). In 2% (1 case), the view was entirely obscured by artifact (Grade 2). Views of the contralateral CPA and IAM were unimpaired in all cases. The best 3 sequences for the depiction of the ipsilateral IAM-CPA (percent graded as 0) were as follows: axial 3D inversion recovery prepared fast spoiled gradient echo (100%), 2 mm coronal T1W of the IAM-CPA (88.9%), and 2 mm axial T1W of the IAM-CPA (76.9%). CONCLUSION: MRI scanning without magnet removal is safe and well tolerated in NF2 patients with auditory implants. With appropriate MRI sequences, the image quality is not significantly impaired.

Squamous cell carcinoma of the temporal bone: clinical outcomes from radical surgery and postoperative radiotherapy.

OBJECTIVE: To review the treatment of squamous carcinoma of the temporal bone at a regional skull base unit for the period 1982-2012. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Sixty patients with primary squamous carcinoma of the temporal bone. INTERVENTIONS: Multidisciplinary team approach including surgical resection, reconstruction, and postoperative radiotherapy. MAIN OUTCOME MEASURES: Disease-specific survival, overall survival. RESULTS: The 5-year disease-specific survival for the whole cohort was 44% (CI, 37%-51%). Multivariable analysis revealed nodal status, poorly differentiated squamous cell histology, and carotid involvement to be poor prognostic indicators. CONCLUSION: Although the survival figures in this series are comparable with the best outcomes from other units, our experience would suggest improvements can still be achieved by reconsidering the selection of patients for neck dissection and temperomandibular joint excision in early stage disease. We also conclude that postoperative radiotherapy should be delivered to all patients, including surgical salvage cases who may have received previous irradiation. Finally, the minority of patients with poor prognostic features should be offered a more palliative therapeutic approach.

English consensus protocol evaluating candidacy for auditory brainstem and cochlear implantation in neurofibromatosis type 2.

OBJECTIVE: Hearing loss resulting from bilateral vestibular schwannomas (VSs) has a significant effect on the quality of life of patients with neurofibromatosis Type 2 (NF2). A national consensus protocol was produced in England as a guide for cochlear implantation (CI) and auditory brainstem implantation (ABI) in these patients. STUDY DESIGN: Consensus statement. SETTING: English NF2 Service. PARTICIPANTS: Clinicians from all 4 lead NF2 units in England. MAIN OUTCOME MEASURES: A protocol for the assessment, insertion and rehabilitation of CI and ABI in NF2 patients. RESULTS: Patients should undergo more detailed hearing assessment once their maximum aided speech discrimination score falls below 50% in the better hearing ear. Bamford-Kowal-Bench sentence testing scores below 50% should trigger assessment for auditory implantation, as recommended by the National Institute for Clinical Excellence guidelines on CI. Where this occurs in patients with bilateral stable VS or a unilateral stable VS where the contralateral cochlear nerve was lost at previous surgery, CI should be considered. Where VS surgery is planned, CI should be considered where cochlear nerve preservation is thought possible, otherwise an ABI should be considered. Intraoperative testing using electrically evoked auditory brainstem responses or cochlear nerve action potentials may be used to determine whether a CI or ABI is inserted. CONCLUSION: The NF2 centers in England agreed on this protocol. Multisite, prospective assessments of standardized protocols for auditory implantation in NF2 provide an essential model for evaluating candidacy and outcomes in this challenging patient population.