Intra- und postoperative elektrophysiologische Diagnostik

Abstract

Within the context of treatment with cochlear implants (CIs), different electrical and electrophysiological diagnostic procedures are applied both intra- and postoperatively. These assess electrical measures from the CI and electrophysiological measures from CI patients, respectively. The electrophysiological diagnostic procedures comprise measurement of electrically evoked compound action potentials of the auditory nerve, the registration of electrically evoked auditory brainstem potentials and the assessment of electrically evoked auditory cortical potentials. These potentials reflect auditory nerve excitation and stimulus processing in different parts of the ascending auditory pathway for intracochlear electrical stimulation via a CI. For current CIs, assessment of electrode position and examination of the implant's coupling to the auditory nerve are important domains of application for electrophysiological diagnostic procedures. Another substantial application area is the examination of stimulus processing in the auditory pathway. However, the main field of application of these procedures is supporting the fitting of CI speech processors in infants and toddlers on the basis of electrophysiological thresholds.

Aktuelle Trends und Entwicklungen bei der Cochlea-Implantat-Versorgung

“…B. dann auf, wenn die Sicht erschwert ist [76]. Bei Fehlbildungen kann ein Reflex oft nicht ausgelöst werden [77].…”

Cochlea-Implantation: Konzept, Therapieergebnisse und Lebensqualität

“…The amplitude grows with increasing insertion depth, reductions reveal possible mechanical interactions with intracochlear structures, most probably with the basilar membrane. If the reduction can be reversed by correcting the electrode position, a low impact on residual hearing may be expected, otherwise substantial damage must be assumed [4,5]. -Electrical Compound Action Potentials (ECAP) of the auditory nerve evoked by intracochlear electrical stimulation to assess the neural responses of the auditory nerve.…”

“…If the insertion is stopped at the onset of amplitude decrease and the electrode is pulled back or the direction of insertion is changed, the response amplitude may recover. In this way, the maximum insertion depth for hearing preservation can be determined [5,41,42]. There is a good correlation between intraoperative changes and postoperative hearing (▶Fig.…”

“…Dabei werden die Antworten mit den der Reizelektrode benachbarten Kontakten abgeleitet. Sie erlauben in begrenztem Rahmen eine Anpassung des CI an die individuellen Eigenschaften des Hörnerven (NRT based fitting bei Kindern), die Erfassung (von Veränderungen) der elektrischen Stimulierbarkeit des Hörnerven sowie die Messung der elektrischen Feldausbreitung (Electrical Field Imaging EFI) bei Stimulation einzelner Elektrodenkontakte zur Bestimmung der Kanal-Interaktion in der Cochlea 6 . Zusätzlich sind Aussagen zum Funktionsstatus des Hörnerven möglich 7…”

“…To some extent they allow fitting of the CI to the individual properties of the auditory nerve (NRT based fitting in children) and the assessment (of changes) of the electrical stimulating properties of the auditory nerve. In a similar way the spread of excitation for assessing channel interaction inside the cochlea and the electric field distribution can be measured 6 . To some extent, the functional status of the auditory nerve can be checked 7 using this technique.…”