Multi-Magnet Cochlear Implant Technology and Magnetic Resonance Imaging: The Safety Issue.

Despite the spread of novel-generation cochlear-implant (CI) magnetic systems, access to magnetic resonance imaging (MRI) for CI recipients is still limited due to safety concerns. The aim of this study is to assess and record the experiences of Hires Ultra 3D (Advanced Bionics) recipients who underwent an MRI examination. A multicentric European survey about this topic was conducted focusing on safety issues, and the results were compared with the current literature. We collected a total of 65 MRI scans performed in 9 otologic referral centers for a total of 47 Hires Ultra 3D recipients, including, for the first time, 2 children and 3 teenagers. Preventive measures were represented by scanning time and sedation for children. Head wrapping was used in eight cases, and six of the eight cases received local anesthesia, even if both measures were not needed. Only three patients complained of pain (3/65 examinations, 4.6%) due to the tight head bandage, and one of the three cases required MRI scan interruption. No other adverse events were reported. We believe that these results should encourage MRI execution in accordance with manufacturer recommendations for Ultra 3D recipients.

Titanium Biohybrid Middle Ear Prostheses: A Preliminary In Vitro Study.

Ossiculoplasty is a surgical operation performed to restore auditory transmission through the reconstruction of the ossicular chain using prosthetics. Tissue bioengineering has assumed a pivotal role in implementing alternatives to conventional ossicular middle ear replacement prostheses, to overcome extrusion while preserving acoustic properties. This in vitro study aims to explore, for the first time in current literature, the feasibility of a biohybrid middle ear prosthesis, composed of titanium surrounded by a bone extracellular matrix as bio-coating. We have hereby studied the adhesion and proliferation of human adipose-derived mesenchymal stem cells (hASC) on titanium scaffolds in vitro. Moreover, we identified the osteogenic differentiation of hASC using an immunofluorescence assay to analyze osteoblasts' gene expression profiles (Alp, Runx2, Col1a1, Osx, and Bglap), and we counted the presence of collagen as a marker of hASC's ability to secrete an extracellular matrix. We utilized scanning electron microscopy to evaluate the presence of an extracellular matrix on the scaffolds. Our preliminary data demonstrated the titanium's ability to support human adipose-derived mesenchymal stem cell colonization, proliferation, and osteoblastic differentiation, in order to obtain a biohybrid device. Our experience seems encouraging; thus, we advocate for further in vivo research to corroborate our results regarding bone transplantation.

Extrusion and Dislocation in Titanium Middle Ear Prostheses: A Literature Review.

Titanium middle ear (ME) prostheses are widely used in surgical practice due to their acoustic properties. However, they present a significant drawback shared by all synthetic materials currently in use for ME reconstruction: they can be rejected by the organism of the host. In this study, we aim to review the current literature on titanium partial ossicular replacement prostheses (PORPs) and total ossicular replacement prostheses (TORPs) extrusion and dislocation. Eighty articles were analysed after a full article review based on the inclusion and exclusion criteria. The most common indication for reconstruction was chronic otitis media with cholesteatoma. The average extrusion or dislocation rate was 5.2%, ranging from 0 to 35%. The average improvements in the air-bone gap were 12.1 dB (1.6 dB to 25.1 dB) and 13.8 (-0.5 dB to 22.7 dB) for the PORP and TORP groups, respectively. The data reported on this topic are highly variable, demonstrating that functional outcomes are difficult to predict in clinical practice. We believe that the current limitations could be overcome with technological developments, including bioengineering research focused on promoting prosthesis adaptation to the ME environment.

Current trends on subtotal petrosectomy with cochlear implantation in recalcitrant chronic middle ear disorders.

Objective: To establish the safety and effectiveness of subtotal petrosectomy with cochlear implantation in patients affected by chronic middle ear disorders to refractory to previous surgical treatments. Methods: A multicentre, retrospective study was conducted on patients affected by recalcitrant chronic middle ear disorders who underwent cochlear implantation in combination with subtotal petrosectomy. Patients' details were collected from databases of 11 Italian tertiary referral centres. Additionally, a review of the most updated literature was carried out. Results: 55 patients were included with a mean follow-up time of 44 months. Cholesteatoma was the most common middle ear recurrent pathology and 50.9% of patients had an open cavity. 80% of patients underwent a single stage surgery. One case of explantation for device failure was reported among the 7 patients with post-operative complications. Conclusions: Subtotal petrosectomy with cochlear implantation is a benchmark for management of patients with recalcitrant chronic middle ear disorders. A single stage procedure is the most recommended strategy. Optimal follow-up is still debated. Further studies are required to investigate the role of this surgery in paediatric patients.

The usefulness of the O-MAR algorithm in MRI skull base assessment to manage cochlear implant-related artifacts.

Objective: To assess artifact size and MRI visibility when applying the "Orthopedic-Metal Artifact Reduction" (O-MAR) algorithm for cochlear implant (CI) scanning. Methods: Two volunteers were submitted to 1.5 T MRI with an Ultra 3D CI receiver stimulator placed on their head. Four angular CI orientations were adopted: 90, 120, 135 and 160 degrees. Volunteers were scanned in each condition using T1w and T2w TSE sequences, as well as O-MAR sequences, in both axial and coronal planes. Quantitative comparisons were made of signal void and penumbra extent. Additionally, qualitative evaluations of global image quality, MRI readability with respect to 12 anatomical structures and visibility through the penumbra were undertaken. Results: After application of the O-MAR protocol, the radius of the signal void reduced from 50.76 mm to 45.43 mm and from 49.22 mm to 40.15 mm on T1w and T2w TSE axial sequences, respectively (p < 0.05). Qualitatively, sequences acquired with O-MAR produced better outcomes in terms of image quality and anatomical depiction. Despite the area of the penumbra being increased for the O-MAR protocol, visibility through penumbra was improved. Conclusions: Application of O-MAR may provide a complementary strategy to those already in use to obtain diagnostically useful MRI examinations in the presence of a CI, especially in case of skull base diseases requiring MRI monitoring.

Customized Cochlear Implant Positioning in a Patient With a Low- Grade Glioma: Towards the Best MRI Artifact Management.

OBJECTIVE: To report the personalized decision-making pro- cess adopted for a cochlear implant (CI) candidate requiring magnetic resonance imaging (MRI) brain surveillance. STUDY DESIGN: Clinical capsule report. SETTING: Tertiary academic referral center. PATIENT: A 23-year-old man affected by posttraumatic bilat- eral profound hearing loss, already in radiological follow-up for a suspected small left cuneal low-grade glioma. INTERVENTIONS: A multidisciplinary approach involving preoperative MRI simulations and 3D printed (3DP) models aiming to adapt the CI position to facilitate MRI brain lesion visibility. MAIN OUTCOME MEASURES: MRI visibility and surgical approach. RESULTS: Preoperative MRI scans with the placement of an Ultra 3D CI were performed simulating different implant location to assess the brain lesion visibility in MRI. CI was positioned 9 cm away from the external auditory canal with an angle of 90 degrees. To assess the technical feasibility of the surgical procedure, a patient-specific 3DP head model was produced preoperatively. The postoperative course was uneventful, the patient showed a significant benefit from CI, and the brain lesion was highly visible at the MRI follow-up. CONCLUSIONS: The employment of strategies aimed at improving the MRI quality in CI recipients still represents a topic requiring attention. Thanks to multidisciplinary team collaboration, in our case, the CI position was successfully determined to allow unhindered MRI visibility of a specific intracranial structure.

The role of cochlear implant positioning on MR imaging quality: a preclinical in vivo study with a novel implant magnet system.

PURPOSES: To investigate the effects for Ultra 3D cochlear implant (CI) positioning on MR imaging quality, looking at a comprehensive description of intracranial structures in cases of unilateral and bilateral CI placement. METHODS: Four CI angular positions (90°, 120°, 135° and 160°) at 9 cm distance from the outer-ear canal were explored. The 1.5 T MRI assessment included our institutional protocol for the investigation of brain pathologies without gadolinium application. Three investigators (two experienced neuroradiologists and one experienced otoneurosurgeon) independently evaluated the MR findings. A 4-point scale was adopted to describe 14 intracranial structures and to determine which CI positioning allowed the best image quality score and how bilateral CI placement modified MRI scan visibility. RESULTS: A high positive correlation was found between the three blinded observers. Structures situated contralateral from the CI showed high-quality values in all four placements. Structures situated ipsilaterally provided results suitable for diagnostic purposes for at least one position. At 90°, artifacts mainly involved brain structures located cranially and anteriorly (e.g., temporal lobe); on the contrary, at 160°, artifacts mostly influenced the posterior fossa structures (e.g., occipital lobe). For the bilateral CI condition, MR imaging examination revealed additional artifacts involving all structures located close to either CI, where there was a signal void/distortion area. CONCLUSIONS: Suitable unilateral CI positioning can allow the visualization of intracranial structures with sufficient visibility for diagnostic purposes. Bilateral CI positioning significantly deteriorates the anatomical visibility. CI positioning might play a crucial role for patients who need post-operative MRI surveillance.

Leukoplakia in the Oral Cavity and Oral Microbiota: A Comprehensive Review.

We reviewed the current published literature on the impact of oral microbiota on oral cavity leukoplakia (OLK), aiming at clarifying its role in disease transformation. The analysis unveiled that bacterial richness and diversity in the oral cavity tend to be decreased in OLK compared to healthy controls, with a reduction in the prevalent commensals, such as Streptococci, and elevation of anaerobes. Moreover, Fusobacterium nucleatum, Porphyromonas gingivalis and Prevotella intermedia are recurrent findings, and they already have been linked to periodontal disease. These microbial community changes may also represent a marker for the transition from OLK to oral squamous cell carcinoma. Unfortunately, the reviewed studies present several limitations, making an objective comparison difficult. To overcome these biases, longitudinal studies are necessary.

Isolated Eustachian Tube Osteoma: Common Lesion in Uncommon Site.

Isolated Eustachian tube osteomata are a very rare entity indeed, with the last case being reported in 1979. We describe a case of the otoscopic finding of a blue-yellowish eardrum and successive identification by computed tomography scan of an osteoma localized in the Eustachian tube. Clinical presentation and diagnostic and therapeutic phases in comparison with the literature will be discussed.

A 3D printed custom-made mask model for frameless neuronavigation during retrosigmoid craniotomy. A preclinical cadaveric feasibility study.

BACKGROUND: A 3D printing custom-made mask model was tested in terms of feasibility and accuracy for frameless neuronavigation during retrosigmoid approach. METHODS: A virtual 3D model of a cadaveric injected head was obtained from a high-resolution Computed Tomography (CT) scan and 3D Printed (3DP). The course of the transverse and sigmoid sinus was marked. A transparent custommade 3DP mask model was created as a cast of 3D model. The area of the lateral sinuses was grooved to allow the surgeon to use the mask as a template to draw the course of the sinuses on the patient skull. A right retrosigmoid approach was performed on formalin-fixed injected cadaveric head. Inion and other conventional landmarks were used to mark the course of the sinuses. 3DP mask was used to re-mark the course of the sinuses. The mismatch between the landmarks-based and 3DP mask-based track was assumed as a measure of the accuracy of the 3DP mask model. RESULTS: 3DP mask model resulted precise, feasible, easy and fast to use. A perfect interlocking with the retrosigmoid area was noted. Mismatch between the landmarks-based and 3DP mask-based track was of 4 and 6 mm for transverse and sigmoid sinus, respectively. CONCLUSION: 3DP custom-made mask model is feasible, easily reproducible and reliable for the implementation of a frameless neuronavigation during retrosigmoid approach. Its accuracy is greater than that of the bone landmark neuronavigation. In selected cases, 3DP mask can be a valid option to image-guided optical or electromagnetic tracking systems. KEY WORDS: 3D Printing, Neuronavigation, Retrosigmoid Approach, Sigmoid Sinus, Transverse Sinus.

A 3D printed custom-made mask model for frameless neuronavigation during retrosigmoid craniotomy. A preclinical cadaveric feasibility study.

BACKGROUND: A 3D printing custom-made mask model was tested in terms of feasibility and accuracy for frameless neuronavigation during retrosigmoid approach. METHODS: A virtual 3D model of a cadaveric injected head was obtained from a high-resolution Computed Tomography (CT) scan and 3D Printed (3DP). The course of the transverse and sigmoid sinus was marked. A transparent custommade 3DP mask model was created as a cast of 3D model. The area of the lateral sinuses was grooved to allow the surgeon to use the mask as a template to draw the course of the sinuses on the patient skull. A right retrosigmoid approach was performed on formalin-fixed injected cadaveric head. Inion and other conventional landmarks were used to mark the course of the sinuses. 3DP mask was used to re-mark the course of the sinuses. The mismatch between the landmarks-based and 3DP mask-based track was assumed as a measure of the accuracy of the 3DP mask model. RESULTS: 3DP mask model resulted precise, feasible, easy and fast to use. A perfect interlocking with the retrosigmoid area was noted. Mismatch between the landmarks-based and 3DP mask-based track was of 4 and 6 mm for transverse and sigmoid sinus, respectively. CONCLUSION: 3DP custom-made mask model is feasible, easily reproducible and reliable for the implementation of a frameless neuronavigation during retrosigmoid approach. Its accuracy is greater than that of the bone landmark neuronavigation. In selected cases, 3DP mask can be a valid option to image-guided optical or electromagnetic tracking systems. KEY WORDS: 3D Printing, Neuronavigation, Retrosigmoid Approach, Sigmoid Sinus, Transverse Sinus.