Optimierung der Operationstechnik bei Cochlea-Implantationen zur Minimierung von intracochleären Druckschwankungen

Die Indikationen der Cochleaimplantatversorgung in Deutschland haben sich in den letzten Jahren gewandelt. Der Erhalt des Restgehörs zur Nutzung der Elektroakustischen Stimulation ist zunehmend in den Fokus der Forschung geraten. Ziel der Arbeit war es verschiedene Teilaspekte der Cochleaimplantatversorgung unter dem Aspekt der intracochleären Druckveränderung zu untersuchen und die intracochleären Druckveränderungen zu minimieren

Improvement of the surgical options in middle- and inner ear implants

Einführung Die Optimierung der operativen Versorgung bei aktiven Mittel- und Innenohrimplantaten ist Gegenstand aktueller Forschung. In den vergangenen Jahren sind die Indikationen für die Versorgung mit aktiven Mittel- und Innenohrimplantaten zunehmend erweitert worden. Diese Änderungen der Indikationsgrenzen für implantierbare Systeme gingen mit Änderungen der operativen Techniken einher. Die präsentierten Arbeiten befassen sich zum einen mit der Qualitätskontrolle und Verbesserung der operativen Versorgung mittels Mittelohrimplantaten und zum anderen mit intracochleären Druckveränderungen bei Cochleaimplantaten (CI), welche bei dem Erhalt des Restgehörs eine wichtige Rolle spielen. Material und Methoden Bei 20 Patienten, die mit einer Vibrant Soundbridge (Med-El) versorgt wurden, erfolgte eine teilweise retrospektive und teilweise prospektive Evaluation verschiedener Parameter. Hierbei wurde radiologisch die Positionierung des floating mass transducer (FMT) am runden Fenster (RW) untersucht und mit den audiologischen Ergebnissen sowie spezifischen Ankopplungsquotienten verglichen. Die intracochleären Druckmessungen fanden in einem künstlichen Cochleamodell statt. Zum einen wurden intracochleäre Druckveränderungen bei RW-Eröffnung mit verschiedenen Instrumenten, zum anderen wurden Druckveränderungen bei verschiedenen Insertionsgeschwindigkeiten einer Cochlear Implant Elektrode gemessen. Ergebnisse Die Position des FMT in der RW-Nische konnte radiologisch klassifiziert werden. Es zeigte sich eine gute Korrelation zwischen der Position des FMT im RW und den audiologischen Ergebnissen. Die Eröffnungen der RW-Membran mit scharfen oder mechanischen Instrumenten gehen mit erheblichen intracochleären Druckveränderungen einher. Die Eröffnung mit dem Diodenlaser zeigt deutlich geringere maximale Druckwerte. Niedrigere Insertionsgeschwindigkeiten (0,1mm/s) gehen mit deutlich geringeren intracochleären Druckwerten als höhere Insertionsgeschwindigkeiten (2mm/s) einher. Schlussfolgerung Die postoperative radiologische Kontrolle nach FMT Positionierung am RW ermöglicht eine Klassifikation der Lage des FMT im Verhältnis zur RW-Membran. Die audiologischen Ergebnisse korrelieren mit der FMT Position, wenn bestimmte chirurgische Vorgaben eingehalten werden. Die Druckveränderungen im Cochleamodell bei RW-Eröffnung und bei CI Insertion mit verschiedenen Insertionsgeschwindigkeiten sind beträchtlich. Inwieweit diese im Modell gemessenen Druckveränderungen auf die humane Cochlea übertragbar sind, muss weiter untersucht werden. Eine bedeutsame Rolle beim angestrebten Erhalt des Restgehörs nach Cochlear Implantversorgung liegt nahe.Introduction Improvement of the surgical options in active middle ear implants and cochlear implants is widely discussed in the literature. Over the past decades the indication for active middle ear and inner ear implants have been extended. The change of the indications involved new surgical techniques. The presented studies deal with the quality control in middle ear implants and with intracochlear pressure changes due to insertions of cochlear implants which are important in preservation of residual hearing. Material and methods In 20 patients who recieved a Vibrant Soundbridge (Med-El) several parameter were evaluated in a mixed retrospective and prospective observational study. The radiological position of the floating mass transducer (FMT) at the round window (RW) was evaluated and compared with the audiological results and a specific coupplingquotient. Intracochlear pressure measurements took place in an artificial cochlear model. Intracochlear pressure changes related to RW opening with different instruments were measured as well as intracochlear pressure changes due to different insertion speeds of a CI electrode. Results The position of the FMT in the RW niche was classified radiologically. A good correlation was seen between the position of the FMT in the RW and the audiological results. RW openings with sharp tools showed high maximum pressure values, whereas RW opening with the diode laser showed rather low pressure values. Slow insertion speed (0,1mm/s) causes clearly lower intracochlear pressure values than fast insertion speed (2mm/s). Conclusion The postoperative control of the FMT in the RW niche led to a classification of the position of the FMT in proportion to the RW-Membrane. The audiological results correlate if surgical guidelines are kept in mind. Intracochlear pressure changes due to RW opening and CI insertion with different speed of insertion are enormous. To which extent the pressure changes observed in the cochlear model can be transferred to the human cochlear needs further investigation. An important part in preservation of residual hearing in CI surgery can be estimated

In Vivo Measurement of Middle Ear Pressure Changes during Balloon Eustachian Tuboplasty

Sudhoff H, Mittmann P, Todt I. In Vivo Measurement of Middle Ear Pressure Changes during Balloon Eustachian Tuboplasty. BioMed Research International. 2018;2018: 9519204.Background. Balloon Eustachian tuboplasty (BET) is known as a treatment for chronic obstructive Eustachian tube dysfunction (OETD). The precise mechanism of action is not fully understood. Observations in sheep cadavers and human cadavers have shown specific middle ear pressure changes related to BET. Methods. In this prospective study using a microfibre optical pressure sensor, pressure changes during BET were for the first time monitored transtympanically in five normal human middle ears in vivo. Results. Middle ear pressure changes during 21 BETs consisted of five stages (insertion, inflation, deflation, withdrawal, and recovery). The highest pressure change occurred in most of the cases during the withdrawal of the balloon catheter. Withdrawal pressure yielded a mean middle ear pressure of 4.76 mmHg (61.89 daPa) with a maximum of 13.88 mmHg (179.55 daPa). Pressure amplitudes capable of causing barotrauma to ear structures were not detected. Internal carotid artery dehiscences were detected as causative of sinusidual pressure changes. Conclusion. The middle ear pressure changes detected in vivo during BET can be attributed to the balloon inflation. Further human studies with patients affected by OETD are necessary to gain more insight into the mechanism of action of BET to clarify a possible pressure related second mechanism of action of BET

In Vivo Measurement of Middle Ear Pressure Changes during Balloon Eustachian Tuboplasty

Background. Balloon Eustachian tuboplasty (BET) is known as a treatment for chronic obstructive Eustachian tube dysfunction (OETD). The precise mechanism of action is not fully understood. Observations in sheep cadavers and human cadavers have shown specific middle ear pressure changes related to BET. Methods. In this prospective study using a microfibre optical pressure sensor, pressure changes during BET were for the first time monitored transtympanically in five normal human middle ears in vivo. Results. Middle ear pressure changes during 21 BETs consisted of five stages (insertion, inflation, deflation, withdrawal, and recovery). The highest pressure change occurred in most of the cases during the withdrawal of the balloon catheter. Withdrawal pressure yielded a mean middle ear pressure of 4.76 mmHg (61.89 daPa) with a maximum of 13.88 mmHg (179.55 daPa). Pressure amplitudes capable of causing barotrauma to ear structures were not detected. Internal carotid artery dehiscences were detected as causative of sinusidual pressure changes. Conclusion. The middle ear pressure changes detected in vivo during BET can be attributed to the balloon inflation. Further human studies with patients affected by OETD are necessary to gain more insight into the mechanism of action of BET to clarify a possible pressure related second mechanism of action of BET

Can hearing amplification improve presbyvestibulopathy and/or the risk-to-fall ?

Purpose!#!The decline of sensory systems during aging has been widely investigated and several papers have correlated the visual, hearing and vestibular systems and the consequences of their functional degeneration. Hearing loss and presbyvestibulopathy have been found to be positively correlated as is with the risk-to-fall.!##!Material and methods!#!The present study was therefore designed as systematic review (due to PRISMA criteria) which should correlate hearing amplification by hearing aids and/or cochlear implants with balance outcome. However, the literature review (Cochrane, PubMed) revealed ten paper (prospective, controlled trials and acute trials) with heterogenous patient popiulations and non-uniform outcome measures (i.e., gait analysis, questionnaires, postural stabilometry) so that no quantitative, statistical analysis could be performed.!##!Results!#!The qualitative analysis oft he identified studies showed that hearing amplification in the elderly improves spatio-temporal orientation (particularly with cochlear implants) and that the process of utilizing auditory information for balance control takes some time (i.e., the neuroplasticity-based, learning processes), usually some months in cochlear implantees.!##!Discussion!#!Hearing and balance function degenerate independently from each other and large interindividual differences require a separate neurotological examination of each patient. However, hearing amplification is most helpful to improve postural stability, particularly in the elderly. Future research should focus on controlled, prospective clinical trials where a standardized test battery covering the audiological and neurotological profile of each elderly patient pre/post prescription of hearing aids and/or cochlear implantation should be followed up (for at least 1 year) so that also the balance improvements and the risk-to-fall can be reliably assessed (e.g., by mobile posturography and standardized questionnaires, e.g., the DHI)

Cochlear implant electrode sealing techniques and related intracochlear pressure changes

Abstract Background The inserted cochlear implanted electrode is covered at the site of the round window or cochleostomy to prevent infections and leakage. In a surgically hearing preservational concept, low intracochlear pressure changes are of high importance. The aim of this study was to observe intracochlear pressure changes due to different sealing techniques in a cochlear model. Methods Cochlear implant electrode insertions were performed in an artifical cochlear model and the intracochlear pressure changes were recorded in parallel with a micro-pressure sensor positioned in the apical region of the cochlea model to follow the maximum amplitude of intracochlear pressure. Four different sealing conditions were compared: 1) overlay, 2) overlay with fascia pushed in, 3) donut-like fascia ring, 4) donut-like fascia ring pushed in. Results We found statistically significant differences in the occurrence of maximum amplitude of intracochlear pressure peak changes related to sealing procedure comparing the different techniques. While the lowest amplitude changes could be observed for the overlay technique (0.14 mmHg ± 0.06) the highest values could be observed for the donut-like pushed in technique (1.79 mmHg ± 0.69). Conclusion Sealing the electrode inserted cochlea can lead to significant intracochlear pressure changes. Pushing in of the sealing tissue cannot be recommended

Magnetic Resonance Imaging Artifacts and Cochlear Implant Positioning at 1.5 T In Vivo

Objective. Cerebral magnetic resonance imaging with the magnet of the cochlear implant receiver/stimulator in place causes artifacts and hinders evaluation of intracerebral structures. The aim of this study was to evaluate the internal auditory canal and the labyrinth in a 1.5T MRI with the magnet in place. Study Design. Observational study. Setting. Tertiary referral center. Subjects and Methods. The receiver/stimulator unit was placed and fixed onto the head of three volunteers at three different angles to the nasion–outer ear canal (90°–160°) and at three different distances from the outer ear canal (5–9 cm). T1 and T2 weighted sequences were conducted for each position. Results. Excellent visibility of the internal auditory canal and the labyrinth was seen in the T2 weighted sequences with 9 cm between the magnet and the outer ear canal at every nasion–outer ear canal angle. T1 sequences showed poorer visibility of the internal auditory canal and the labyrinth. Conclusion. Aftercare and visibility of intracerebral structures after cochlear implantation is becoming more important as cochlear implant indications are widened worldwide. With a distance of at least 9 cm from the outer ear canal the artifact induced by the magnet allows evaluation of the labyrinth and the internal auditory canal

Cochlear implants and 1.5 T MRI scans: the effect of diametrically bipolar magnets and screw fixation on pain

Abstract Background The probability that a patient will need an MRI scan at least once in a lifetime is high. However, MRI scanning in cochlear implantees is associated with side effects. Moreover, MRI scan-related artifacts, dislodging magnets, and pain are often the most frequent complications. The aim of this study was to evaluate the occurrence of pain in patients with cochlear implant systems using 1.5T MRI scans. Methods In a prospective case study of 10 implantees, an MRI scan was performed and the degree of pain was evaluated by a visual analog scale. Scans were performed firstly with and depending on the degree of discomfort/pain, without a headband. Four of the cochlear implants contained a screw fixation. Six cochlear implants contained an internal diametrically bipolar magnet. MRI observations were performed with a 1.5 T scanner. Results MRI scans were performed on all patients without causing any degree of pain, even without the use of a headband. Conclusion Patients undergoing 1.5 T MRIs with devices including a diametrically bipolar magnet or a rigid implant screw fixation, experienced no pain, even without headbands

Measurement of middle ear pressure changes during balloon eustachian tuboplasty: a pilot study

Todt I, Abdel-Aziz T, Mittmann P, et al. Measurement of middle ear pressure changes during balloon eustachian tuboplasty: a pilot study. Acta Oto-Laryngologica. 2016;137(5):471-475

Sequestome 1 deficiency delays, but does not prevent brain damage formation following acute brain injury in adult mice

Neuronal degeneration following traumatic brain injury (TBI) leads to intracellular accumulation of dysfunctional proteins and organelles. Autophagy may serve to facilitate degradation to overcome protein debris load and therefore be an important pro-survival factor. On the contrary, clearing may serve as pro-death factor by removal of essential or required proteins involved in pro-survival cascades. Sequestosome 1 (SQSTM1/p62) is a main regulator of the autophagic pathway that directs ubiquinated cargoes to autophagosomes for degradation. We show that SQSTM1 protein levels are suppressed 24 h and by trend 5 days after trauma. In line with these data the expression of Sqstm1 mRNA is reduced by 30% at day 3 after and stays depressed until day 5 after injury, indicating an impaired autophagy post controlled cortical impact (CCI). To determine the potential role of SQSTM1-dependent autophagy after TBI, mice lacking SQSTM1 (SQSTM1-KO) and littermates (WT) were subjected to CCI and brain lesion volume was determined 24 h and 5 days after insult. Lesion volume is 17% smaller at 24 h and immunoblotting reveals a reduction by trend of cell death marker αII-spectrin cleavage. But there is no effect on brain damage and cell death markers 5 days after trauma in SQSTM1-KO compared with WT. In line with these data neurofunctional testing does not reveal any differences. Additionally, gene expression of inflammatory (Tnf-α, iNos, Il-6, and Il-1β) and protein degradation markers (Bag1 and Bag3) were quantified by real-time PCR. Protein levels of LC3, BAG1, and BAG3 were analyzed by immunoblotting. Real-time PCR reveals minor changes in inflammatory marker gene expression and reduced Bag3 mRNA levels 5 days after trauma. Immunoblotting of autophagy markers LC3, BAG1, and BAG3 does not show any difference between KO and WT 24 h and 5 days after TBI. In conclusion, genetic ablation of SQSTM1-dependent autophagy leads to a delay but shows no persistent effect on post-traumatic brain damage formation. SQSTM1 therefore only plays a minor role for secondary brain damage formation and autophagic clearance of debris after TBI