Effect of head position on cochlear implant MRI artifact.

PURPOSE: A new generation of cochlear implant (CI) magnets and specific surgical techniques (e.g., implant positioning) has changed the relationship between a CI and magnet resonance imaging (MRI). MRI allows a pain free in vivo evaluation of the inner ear fluid state and internal auditory canal after the insertion of an electrode. The aim of this study is to evaluate how the patient's head position in the MRI scanner influences the CI magnet-related artefact. METHODS: We performed in vivo measurement of MRI artefacts at 3 T with a CI system containing a bipolar diametrical magnet. The implant magnet was positioned with a head bandage at different positions from the nasion and external auditory canal in three volunteers. We used a turbo spin echo (TSE) T2w sequence on the axial and coronal planes and observed three positions: (1) regular position, (2) chin to chest (anteflexion), and (3) hyperextension (retroflexion). RESULTS: By comparing the positions, anteflexion of the cervical spine in a chin-to-chest position allowed us to place the artefact in a more apical position from the IAC in the coronal plane. The hyperextension of the cervical spine position shifts the artefact father towards the cochlea's direction. CONCLUSION: The head's position can influence the location of MRI artefacts. In cases where the artefact diminished the IAC or cochlea, anteflexion of the cervical spine in the chin-to-chest position of the head in the MRI scanner should be attempted to allow a visualization of the IAC.

[Ectopic thyroid tissue after total thyroidectomy]. / Ektopes Schilddrüsengewebe nach erfolgter Thyreoidektomie.

Ectopic thyroid gland tissue can occur either as the only detectable thyroid gland tissue or in addition to a normotopic thyroid gland. After a total thyroidectomy thyroid-stimulating hormone (TSH) can induce a compensatory volume increase of previously asymptomatic ectopic tissue. This hyperplastic ectopic tissue can occur as an unclear cervical space-occupying lesion. Prior to surgical exploration of an unclear cervical mass the possibility of ectopic thyroid tissue should be included in the differential diagnostic considerations.

[A rare pathology of the petrous part of the temporal bone: adenoma of the middle ear]. / Eine seltene Pathologie des Felsenbeins: Das Adenom des Mittelohres.

Adenomas are very rare tumors of the middle ear. They are benign neoplasms originating from the glandular components of the mucous membrane of the middle ear. The middle ear adenoma was first described by Hyams and Michaels in 1976, which was named an adenomatous tumor. This article reports the case of a 50-year-old female patient, who presented with recurrent right-sided dull otalgia and pulse synchronous tinnitis, which began 1 year prior to presentation, with the suspected diagnosis of a glomus tympanicum tumor. Following the otorhinolaryngological examination and imaging an unclear mesotympanal space-occupying lesion was detected. A transmeatal endoscopic complete removal of the tumor was carried out. The histopathological investigations enabled the diagnosis of an adenoma of the middle ear. Adenomas are a rare differential diagnosis of tumors of the middle ear. In cases with a suitable localization an adequate exposure and removal of this rare tumor can be achieved by a transmeatal endoscopic access.

Postoperative imaging of the internal auditory canal : Visualization of active auditory implants.

BACKGROUND: Assessment of the internal auditory canal (IAC) and cochlea is of central importance in neurotology. The artefacts and visibility of active auditory implants on magnetic resonance imaging (MRI) vary because of their specific magnetic components. Knowledge of the size of MRI artefacts and the options for handling them is important for the auditory rehabilitation of specific diseases (e. g., vestibular schwannoma). METHODS: The current article is a literature review. RESULTS: MRI assessment of the IAC and cochlea after surgical placement of an active auditory implant is feasible only with a percutaneous bone-anchored hearing aid (BAHA, Ponto). When specific factors (implant position and MRI sequence) are taken into consideration, these structures can be visualized even after cochlear implantation. Complications such as magnet dislocation and pain may occur. CONCLUSION: The possibility of assessing the IAC and cochlea by MRI is an important aspect that needs to be taken into consideration when planning the auditory rehabilitation of patients after acoustic neuroma surgery.

[Postoperative imaging of the internal auditory canal : Visualization of active auditory implants. German version]. / Postoperative Bildgebung des inneren Gehörgangs : Darstellung aktiver auditorischer Implantate.

BACKGROUND: Assessment of the internal auditory canal (IAC) and the cochlea is of central importance in neurotology. The artefacts and visibility of the different types of active auditory implants in MRI vary, due to their specific ferromagnetic components. Knowledge of the size of MRI artefacts and the options for handling these is important for the auditory rehabilitation of specific diseases (e. g., vestibular schwannoma). METHODS: The current paper is a literature review RESULTS: MRI assessment of the IAC and cochlea after surgical placement of an active auditory implant is feasible only with a percutaneous bone-anchored hearing aid (BAHA, Ponto). When specific factors (implant position and MRI sequence) are taken into consideration, these structures can be visualized even after cochlear implantation. Complications such as magnet dislocation and pain may occur. CONCLUSION: The possibility of assessing the IAC and cochlea by MRI is an important aspect that needs to be taken into consideration when planning the auditory rehabilitation of patients after acoustic neuroma surgery.

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.

Optimisation of the round window opening in cochlear implant surgery in wet and dry conditions: impact on intracochlear pressure changes.

To preserve residual hearing in cochlear implant candidates, the atraumatic insertion of the cochlea electrode has become a focus of cochlea implant research. In a previous study, intracochlear pressure changes during the opening of the round window membrane were investigated. In the current study, intracochlear pressure changes during opening of the round window membrane under dry and transfluid conditions were investigated. Round window openings were performed in an artificial cochlear model. Intracochlear pressure changes were measured using a micro-optical pressure sensor, which was placed in the apex. Openings of the round window membrane were performed under dry and wet conditions using a cannula and a diode laser. Statistically significant differences in the intracochlear pressure changes were seen between the different methods used for opening of the round window membrane. Lower pressure changes were seen by opening the round window membrane with the diode laser than with the cannula. A significant difference was seen between the dry and wet conditions. The atraumatic approach to the cochlea is assumed to be essential for the preservation of residual hearing. Opening of the round window under wet conditions produce a significant advantage on intracochlear pressure changes in comparison to dry conditions by limiting negative outward pressure.

Electrophysiological detection of scalar changing perimodiolar cochlear electrode arrays: a long term follow-up study.

The position of the cochlear electrode array within the scala tympani is essential for an optimal hearing benefit. An intraoperative NRT-ratio was established, which can provide information about the intraoperative intracochlear electrode array position for perimodiolar electrodes. The aims of this study were to verify the longterm reliability for the NRT-ratio in perimodiolar electrodes. In a retrospective controlled study in a Tertiary Referral Center the electrophysiological data sets of 123 patients with implanted Nucleus Contour Advance electrodes were enclosed. Intraoperative and up to 1 year follow-up Auto-NRTs were evaluated. A NRT-ratio was calculated by dividing the average Auto-NRT data from electrode 16 to 18 with the average from electrode 5 to 7. Using a flat panel tomography system, the position of the electrode array was certified radiological. 31 patients with perimodiolar electrodes with 1 year follow-up data were included in the study. Eleven patients showed regular follow-up NRT-ratio with a correlated and radiologically confirmed electrode position. 20 patients showed mismatches between the NRT-ratio and the radiological position. These patients were highly variable in terms of duration of deafness and neural spectrum disorders. The NRT-ratio can be used to determine the intracochlear position of the electrode array for perimodiolar electrodes. Intraoperatively the NRT-ratio predicts the array position within the cochlea highly reliable for perimodiolar electrodes. We showed that after 6 months and a year, the NRT-ratio remains unchanged in most of the cases and shows a good correlation to the radiological determined position of the array. Nevertheless, the condition of the neural structures is highly important for reproducible responses. Limited validity is given in patients with degenerative and structural neural disorders.

[Dehiscence syndromes : Diagnosis and treatment]. / Dehiszenzsyndrome : Diagnostik und Therapie.

BACKGROUND: Dehiscence syndromes of the semicircular canals are a relatively new group of neurotological disorders. They have a variety of symptoms with hearing/balance involvement. Younger patients have clinically relevant symptoms in only about one third of cases. In addition to etiology and pathogenesis, the present paper describes diagnostic and therapeutic possibilities using a patient series of the authors. MATERIALS AND METHODS: This nonrandomized prospective study included 52 patients with uni-/bilateral dehiscence syndromes of the superior and/or posterior canal (SCDS/PCDS), diagnosed with high-resolution computed tomography (HR-CT) of the petrous bone. Of 41 patients undergoing surgical therapy for severe symptoms-predominantly vertigo attacks (Meniere-like) and/or falls (Tumarkin crises)-31 received single-sided hearing implants. RESULTS: Of the 41 patients with transmastoid superior and/or posterior canal occlusion, 30 showed a significant improvement of balance in the Dizziness Handicap Inventory (DHI); the dizzy spells ceased. A positive outcome was correlated with the severity of the preoperative disorder; a poor outcome (nonsignificant increase in DHI, recurrent vertigo of various qualities/frequencies) with the comorbidities vestibular migraine, Menière's disease of the contralateral ear, and a dehiscence size exceeding 4 mm. CONCLUSION: The more severe the vestibular symptoms, the better the outcome of surgical therapy. Auditory symptoms (nonspecific aural fullness, hyperacusis) do not generally respond well to surgical therapy. Cochlear implants have an additional beneficial effect; comorbidities should be considered as (relative) contraindications.

[Osteoradionecrosis of the sternoclavicular joint]. / Osteoradionekrose des Sternoklavikulargelenks.

BACKGROUND/OBJECTIVE: Osteoradionecrosis is a rare, but feared, late complication after radiotherapy of the head and neck region. Its localization to the sternoclavicular joint has rarely been described so far. MATERIALS AND METHODS: Data are from a retrospective study that included all patients admitted to the authors' clinic with osteoradionecrosis of the sternoclavicular joint during the last 5 years. Therapy and outcome were evaluated and compared to the established literature. RESULTS: Over the past 5 years, 2 patients have been treated for pronounced osteoradionecrosis of the sternoclavicular joint. Both patients had received postoperative radiotherapy for tumors of the neck and chest, and presented with lesions involving the clavicle and the sternum. After eliminating the suspicion of recurrent cancer, both radiologic imaging and histopathologic evaluation confirmed an infection. Aggressive debridement with partial claviculectomy, partial sternectomy, and reconstruction using a pectoralis flap lead to the patients' recovery. CONCLUSION: Osteoradionecrosis does not only affect bone, but also the surrounding soft tissue. Due to the changes associated with previous radiotherapy, osteoradionecrosis should always be treated with radical debridement of the infected area, followed by flap reconstruction using unaffected tissue. The prognosis for the patient is then good.

[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.

Intracochlear pressure changes due to round window opening: a model experiment.

To preserve residual hearing in cochlea implantation, the electrode design has been refined and an atraumatic insertion of the cochlea electrode has become one aspect of cochlea implant research. The opening of the round window can be assumed to be a contributing factor in an atraumatic concept. The aim of our study was to observe intracochlear pressure changes due to different opening conditions of an artificial round window membrane. The experiments were performed in an artificial cochlea model. A round window was simulated with a polythene foil and a pressure sensor was placed in the helicotrema area to monitor intraluminal pressure changes. Openings of the artificial round window membrane were performed using different ways. Opening the artificial round window mechanically showed a biphasic behaviour of pressure change. Laser openings showed a unidirectional pressure change. The lowest pressure changes were observed when opening the artificial round window membrane using a diode laser. The highest pressure changes were seen when using a needle. The openings with the CO2 laser showed a negative intracochlear pressure and a loss of fluid. In our model experiments, we could prove that the opening of the artificial round window membrane causes various intracochlear pressure changes.

[Development of a computed tomography data-based Vibrant Bonebridge viewer]. / Entwicklung eines CT-Daten-basierten Vibrant-Bonebridge-Viewers.

BACKGROUND: Because of the anatomy of the mastoid and the size of the actuator, positioning of the Vibrant Bonebridge B-FMT can be difficult without prior evaluation of the individual computed tomography (CT) scan of the temporal bone. Development of a user-friendly CT data viewer to enable positioning of the B-FMT in the temporal bone model, whilst identifying individual, potential anatomic conflicts and offering possible solutions could provide a useful tool for preoperative positioning. OBJECTIVES: Aim of the study was to define the requirements of a Vibrant Bonebridge viewer and construct a prototype. MATERIALS AND METHODS: Based on a ZIBAmira software version and inclusion of a B-FMT model upon creation of a model of the temporal bone-which allows the intuitive estimation of individual, anatomic conflicts-a Vibrant Bonebridge viewer was constructed. RESULTS: The segmentation time of the individual digital imaging and communications in medicine (DICOM) data set is about 5 min. Positioning within the individual three-dimensional temporal bone model allows quantitative and qualitative estimation of conflicts (sigmoid sinus, middle cranial fossa) and determination of a preferred position for the B-FMT. Lifting of the B-FMT can be simulated with the help of a virtual washer. CONCLUSION: The Vibrant Bonebridge viewer reliably allows simulation of B-FMT positioning. The clinical value of the viewer still has to be evaluated.

Perilymph Fistula as a Complication of Eustachian Tube Dilation and Tympanoplasty.

Eustachian tube dilation (ETD) is an established, minimally invasive therapeutic approach for chronic eustachian tube dysfunction. The complications associated with performing a ETD are rare. A 22-year-old female patient presented with chronic otitis media on the right side and chronic obstructive tube dilation disorder on both sides. A type I tympanoplasty was performed on the right side because of a tympanic membrane perforation after a ETD on both sides without apparent complications. On the 5th postoperative day, she presented with headache, dizziness and hearing loss on the right side. There was a decrease of hearing threshold on the right side in the pure-tone audiogram and vHIT, cVEMP, and SVV were irregular. The ß-2-transferrin test was positive. Since a right-sided perilymph fistula was suspected, an emergency tympanotomy was performed with a round window membrane cover with fascia on the right side. Intraoperatively, a regular, intact ossicular chain was found with a slightly moist middle ear mucosa. The round window membrane was covered by the promontorial lip. Under these measures, the patient's dizziness regressed. The right ear pure-tone threshold vHIT, cVEMP, and SVV normalized.

Ipsilateral Vestibular Schwannoma after Cochlear Implantation.

OBJECTIVE: The vestibular schwannoma incidence rate is approximately 4.2 per 100,000/year. Thus far, about 700,000 cochlear implantations have been performed worldwide; therefore, the occurrence of vestibular schwannoma postcochlear implantations can be assumed to be infrequent. Recent developments allow safe observation and surveillance of the implanted-side internal auditory canal (IAC) and cochlea by magnetic resonance imaging (MRI), even after cochlear implantation. Patients. A 71-year-old woman with sudden hearing loss and a contralateral vestibular schwannoma without clinical and genetic signs of neurofibromatosis type II. Intervention(s). Ipsilateral cochlear implantation and contralateral vestibular schwannoma extirpation with regular tumor follow-up. Main Outcome Measure(s). Comparison of ipsilateral pre and postcochlear implantation 3T MRI T1 GAD. RESULTS: We observed a tumor growing at the fundus of the internal auditory canal 1 year after cochlear implantation on the ipsilateral side. Although first detected after cochlear implantation beside a known vestibular schwannoma on the contralateral side, a scan slice thickness of 2 mm cannot fully exclude the preoperative persistence of a small tumor. Based on the clinical findings and after genetic exclusion of NFII, the patient was classified as a NFII mosaic type. CONCLUSION: Even after cochlear implantation, tumors in the IAC causing vertigo, facial palsy, and affecting the audiologic outcome can be detected by MRI. The MRI slice thickness used before cochlear implantation should be under 2 mm.

[Posttraumatic laryngotracheal separation]. / Posttraumatische laryngotracheale Separation.

Laryngotracheal trauma is rare and may lead to airway obstruction and life-threatening situations. We present a case report of laryngotracheal separation after a horse riding accident. In this case, early intubation secured the respiratory passage and the life of the patient.

Evaluation of cochlear implant electrode scalar position by 3 Tesla magnet resonance imaging.

The estimation of scalar electrode position is a central point of quality control during the cochlear implant procedure. Ionic radiation is a disadvantage of commonly used radiologic estimation of electrode position. Recent developments in the field of cochlear implant magnets, implant receiver magnet position, and MRI sequence usage allow the postoperative evaluation of inner ear changes after cochlear implantation. The aim of the present study was to evaluate the position of lateral wall and modiolar cochlear implant electrodes using 3 T MRI scanning. In a prospective study, we evaluated 20 patients (10× Med-El Flex 28; 5× HFMS AB and 5× SlimJ AB) with a 3 T MRI and a T2 2D Drive MS sequence (voxel size: 0.3 × 0.3 × 0.9 mm) for the estimation of the intracochlear position of the cochlear implant electrode. In all cases, MRI allowed a determination of the electrode position in relation to the basilar membrane. This observation made the estimation of 19 scala tympani electrode positions and a single case of electrode translocation possible. 3 T MRI scanning allows the estimation of lateral wall and modiolar electrode intracochlear scalar positions.