Prospective study on magnetic resonance imaging in cochlear implant patients.

PURPOSE: Monocentric, prospective study to investigate whether concomitant support of cochlear implant (CI) patients by CI-trained otolaryngologists and application of a standardized head bandage can minimize potential complications during magnetic resonance imaging (MRI). METHODS: Thirty-seven patients with 46 CIs underwent MRI with a prophylactic head bandage. All participants and the otolaryngologist at the CI center completed pre- and post-MRI questionnaires documenting body region scanned, duration of MRI and bandage wear, field strength during the scan, and any complications. If pain was experienced, it was assessed using a visual analog scale (1-10). RESULTS: MRI was performed without adverse events in 37.8% of cases. Magnet dislocation requiring surgical revision occurred in 2% of cases. Pain was reported in 86% of cases, often due to the tightness of the dressing. Patients with rotating, MRI-compatible magnets reported significantly less pain than participants with older-generation implants. In 11% of cases, the MRI was discontinued. CONCLUSION: Serious complications during MRI in cochlear implant patients are rare. Pain is the most common adverse event, probably mainly due to the tight bandage required by most implant types. With newer generations of magnets, these patients experience less pain, no dislocation of the magnets, and no need for bandaging. Although magnet dislocation cannot be completely prevented in older generations of implants, it appears to be reduced by good patient management, which recommends examination under the guidance of physicians trained in the use of hearing implants.

Diagnosing complications following cochlear implantation using transcutaneous ultrasound.

PURPOSE: The aim of this study was to investigate the feasibility and reliability of transcutaneous ultrasound for the detection of complications after cochlear implantation. METHODS: In a single center retrospective cohort study, 115 consecutive cases of suspected complications after cochlear implantation (intervention group) were examined. The rate of pathologic ultrasound findings for specific leading symptoms and diagnoses was compared to a control group comprising twenty consecutive cochlear implants in symptom-free patients. RESULTS: Diagnostic ultrasound showed distinctly more pathologic findings in the intervention group (n = 67; 58.3%; p < 0.001) compared to the control group (n = 1; 5%). Ultrasound revealed significantly more pathologic findings in haematoma or seroma around the implant (n = 17; 100%; p < 0.001; ϕ = 0.94) and magnet dislocation (n = 44; 97.7%; p < 0.001; ϕ = 0.92) confirmed by a strong effect. Ultrasound examination showed a medium to high effect size in patients presenting with local infections (n = 3; 21.4%; p = 0.283; ϕ = 0.25) and skin flap oedema (n = 2; 50%; p = 0.061; ϕ = 0.51). In contrast, ultrasound examinations displayed a low effect size in undefined cephalgia (0%; p = 0.444; ϕ = 0.17) and device malfunction or failure (0%; p > 0.999; ϕ = 0.13). CONCLUSION: Transcutaneous ultrasound can be advocated as a feasible and effective method in the diagnostic work-up of magnet dislocation and haematoma or seroma around the implant following cochlear implantation. Contrary, ultrasound findings can be expected to be inconspicuous in patients presenting with undefined cephalgia and device malfunction or failure.

Comparison of bandaging techniques to prevent cochlear implant magnet displacement following MRI.

INTRODUCTION: For cochlear implants (CI) with removable magnets, a pressure bandage usually is recommended during MR imaging to avoid magnet dislocation. Nevertheless, this complication is regularly observed despite applying a pressure bandage. The aim of this study was to compare various bandaging techniques to avoid magnet displacement. MATERIALS AND METHODS: As an experimental model a force measuring stand was developed and validated, on which the process of magnet dislocation could be simulated on a cochlear implant. In a test series with six combinations of cohesive and elastic bandages with different counter pressure elements (CPE), the forces required to induce magnet dislocation against the resistance of a compression bandage was determined. In addition, the inter- and intraindividual variability of the compression bandages was measured for ten different users. RESULTS: The cohesive bandage had the lowest average holding force of 10.70 N. The elastic bandage developed more than four times the retention force of the cohesive bandage (44.88 N, p < 0.01). By adding a CPE, these values could be increased highly significantly up to factor 3. The optimum combination in terms of fixation force against magnet dislocation was an elastic bandage plus a cylindrical CPE (76.60 N). The data showed a high interindividual variability. CONCLUSION: Even though most CI manufacturers now offer 3T-conditional implants, a pressure bandage will have to be applied to thousands of patients with previous implant generations to prevent magnet dislocation. We examined for the first time force measurements to compare different bandaging techniques by detecting the holding force of the CI magnet. We were able to identify an optimized combination of a bandage and a CPE to immobilize the CI magnet. However, our data also demonstrated a significant scatter amongst different examiners. Although our data provide valuable data for potential clinical application, future development of the dressing technique is required for human use.

Prevalence and complications of MRI scans of cochlear implant patients : English version.

BACKGROUND: Cochlear implants (CI) are the preferred method of treatment for patients with severe to profound bilateral sensorineural hearing loss and unilateral deafness. For many years, because of the magnetic field applied during magnetic resonance imaging (MRI) examinations, MRI examinations were contraindicated for CI patients or feasible only under specific circumstances. MRI examinations of CI recipients entail complications and therefore preventive measures have to be considered. The aim of this study was to evaluate the prevalence of MRI scans in CI recipients and the occurrence of complications and furthermore to investigate the preventive measures taken in radiological daily routine. MATERIALS AND METHODS: A retrospective questionnaire was sent to 482 patients that received CIs from 1999-2013. Details of the MRI examination and subjective and objective incidents during and after the MRI scan were evaluated. RESULTS: A total of 204 CI recipients answered the retrospective questionnaire (42.3 %). Twenty patients (9.8 %) with 23 implants underwent a total of 33 MRI scans with their cochlear implant in place. In 16 cases the scanned region was the head (49 %). Preventive measures in the form of head bandages were taken in 20 cases (61 %). The most common complication was pain in 23 cases (70 %) and the most serious complication was the dislocation of the internal magnet in 3 cases (9 %). CONCLUSIONS: The number of CI recipients undergoing MRI scans is high. Possible complications and preventive measures attract too little attention in radiological daily routine.

[Prevalence and complications of MRI scans of cochlear implant patients: German version]. / Häufigkeit und Komplikationen von MRT-Untersuchungen bei Cochlea-Implantat-Patienten: German version.

BACKGROUND: Cochlear implants (CI) are the preferred method of treatment for patients with severe to profound bilateral sensorineural hearing loss and unilateral deafness. For many years, because of the magnetic field during magnetic resonance imaging (MRI) examinations, MRI examinations were contraindicated for CI patients or feasible only under specific circumstances. MRI examinations of CI recipients entail complications and therefore preventive measures have to be considered. The aim of this study was to evaluate the incidence of MRI scans in CI recipients and the occurrence of complications, and furthermore to investigate the preventive measures taken in radiological daily routine. MATERIALS AND METHODS: A retrospective questionnaire was sent to 482 patients that received CIs from 1999-2013. Details of the MRI examination and subjective and objective incidents during and after the MRI scan were evaluated. RESULTS: A total of 204 CI recipients answered the retrospective questionnaire (42.3%). Twenty patients (9.8%) with 23 implants underwent a total of 33 MRI scans with their cochlear implant in place. In 16 cases the scanned region was the head (49%). Preventive measures in the form of head bandages were taken in 20 cases (61%). The most common complication was pain in 23 cases (70%) and the most serious complication was the dislocation of the internal magnet in 3 cases (9%). CONCLUSIONS: The number of CI recipients undergoing MRI scans is quite high. Possible complications and preventive measures attract too little attention in radiological daily routine.

Surgical Versus Noninvasive Manual Repositioning After Cochlear Implant Partial Magnet Dislocation.

Objectives: To compare surgical magnet repositioning (SMR) and noninvasive manual magnet repositioning (MMR) as treatments for partial magnet dislocation (PMD) of the internal magnet in a cochlear implant (CI) caused by magnetic resonance imaging (MRI). The primary objective was the success rate, while the secondary objectives were total postinterventional CI downtime and complications. Methods: This single-center retrospective study was conducted at a tertiary referral medical center. Patients with CI treated for PMD between January 1, 2007 and September 30, 2022 were included. SMR served as primary treatment until June 2019 and as secondary treatment after the introduction of MMR. Results: A total of 51 cases of PMD were observed in 42 patients and 43 devices (18 ♀; 24 ♂; 12 with bilateral CI). MMR was performed successfully in 19 out of 20 cases (95%), while 32 cases were managed successfully by SMR. The median age at first magnet repositioning was 53.8 years (minimum 19 years, maximum 93 years). When MMR was performed, the mean time from diagnosis to treatment (0.5 ± 1.5 days vs 9.8 ± 7.6 days; P < .01), the mean time from repositioning to CI reactivation (1.4 ± 4.3 days vs 13.1 ± 6.7 days; P < .01), and the mean total CI downtime (1.9 ± 4.8 days vs 22.9 ± 11.9 days; P < .01) were significantly shorter compared to SMR. Significantly fewer complications were experienced with MMR [n = 0 (0%) vs n = 8 (25%); P = .04]. Conclusion: In case of PMD caused by MRI, noninvasive MMR shows a high success rate with a shorter total CI downtime as well as a lower complication rate compared to SMR. Therefore, MMR should be considered as first line treatment with SMR as a second option in case of failure.

Risk of magnetic resonance imaging-induced magnet dislocation for different types of cochlear implants: a single-center retrospective study.

BACKGROUND: When performing magnetic resonance imaging (MRI) in patients with a cochlear implant (CI), complication rates vary widely in the literature. The primary objective of this retrospective study was to determine the prevalence of complications, in particular magnet dislocation, in patients with CI undergoing 1.5 Tesla (T) MRI. As a secondary objective, the prevalence of magnet dislocation for specific cochlear implant device types was elaborated. METHODS: In a single-center retrospective study, all patients with a cochlear implant presenting for an MRI examination at 1.5 T at our institution between January 1st, 2010 and December 31st, 2020 were included. Implants with axial and diametrical magnets were included in the study. MRI safety measures were applied before imaging. The prevalence of complications was evaluated. Magnet dislocation rates were calculated for device types with at least 20 MRI exposures. RESULTS: During the study period, 196 MRI examinations were performed in a total of 128 patients, accounting for 149 different implants (21 implanted bilaterally) with a total of 231 implant exposures to MRI (average 1.69 ± 1.57; min. 1, max. 12). Complications were reported in 50 out of 231 cochlear implant exposures (21.6%). Magnet dislocation occurred in a total of 27 cases (11.7%). Dislocation rates were 29.6% for the Cochlear® CI500 series (24 dislocations from 81 exposures), 1.1% for the Cochlear® CI24RE series (1 from 87) and 0% for the MED-EL® Synchrony (0 from 36). The dislocation rate for the CI500 was significantly higher than for the CI24RE (χ2(1) = 26.86; p < 0.001; ϕ = 0.40) or the Synchrony (χ2(1) = 13.42; p < 0.001; ϕ = 0.34). CONCLUSIONS: For 1.5 T MRI, the risk of magnet dislocation ranges from 0 to 29.6% and depends on the CI device type. Implants with a diametrical magnet can be considered potentially MRI-safe, whereas in CIs with axial magnets, the CI500 is at high risk of magnet dislocation. Therefore, apart from a strict indication for an MRI and adherence to safety protocols, post-MRI follow-up examination to rule out magnet dislocation is recommended.

Magnet dislocation following magnetic resonance imaging in cochlear implant users: Diagnostic pathways and managment.

OBJECTIVES: Although modern cochlear implants (CIs) are approved for magnetic resonance imaging (MRIs) adverse events still occur with unacceptable frequency. Methods: In this retrospective study, magnet displacement due to MRIs was analysed. Relevant factors e.g. symptoms during MRI, diagnostics, surgical intervention following the diagnosis and possible subsequent damage were assessed. RESULTS: 16 patients were enclosed. All patients complained about pain while the scan was conducted. Computed tomography (CT) scans of the temporal bone or X-rays of the skull were performed to confirm diagnosis. Artefacts on CT scans delayed immediate diagnosis in some cases. DISCUSSION: Despite various studies demonstrating the range of adverse events related to CIs following MRI, little information is available on diagnosis and radiologic recognition of magnet dislocation. In patients complaining about pain following an MRI scan an X-ray of the head should be performed immediately. Most adverse events occur in radiological centres without expertise in cochlear implants. CONCLUSION: Comprehensive training of patients, surgeons and radiologists is the most efficient tool to prevent damage to the CI and the patient. X-ray of the skull is suggested to be used as the method of choice in imaging.