Direkte Ableitung vom Nervus cochlearis bei transtemporaler Resektion von Vestibularisschwannomen

Zusammenfassung

Einleitung:

Zur Gewährleistung des Hörerhalts bei der Operation von Vestibularisschwannomen wird ein intraoperatives Monitoring der Funk­tion des Nervus cochlearis durch Ableitung von Hirnstammpotenzialen (BERA) angewandt. In der vorliegenden Studie wurde unter Verwendung einer Kugelelektrode das Aktionspotenzial des Nervus cochlearis nach der Tumorexstirpa­tion direkt am Nerv abgeleitet, um eine Aussage über das postoperative Hörvermögen zu treffen. Die gewonnenen Daten wurden mit den Ergebnissen der gleichzeitig durchgeführten BERA und dem postoperativen Hörvermögen verglichen.

Material und Methoden:

Im Jahr 2009 erhielten 38 Patienten an der Universitäts-HNO-Klinik Würzburg eine Exstirpation eines Vestibularisschwannoms. Bei 33 Patienten erfolgte intraoperativ sowohl eine BERA-Messung als auch die direkte Ableitung am Nervus cochlearis über eine Kugelelektrode. Das Hörvermögen von 5 Patienten wurde intraoperativ nur durch direkte Ableitung am Nervus cochlearis untersucht.

Ergebnisse:

Wenn ein Monitoring mit der BERA nicht mehr möglich war, konnten über eine direkte Ableitung mit einer Kugelelektrode noch aussagekräftige Antworten zur Beurteilung des postoperativen Hörvermögens erhalten werden. Die direkte Ableitung vom Nervus cochlearis hatte dabei eine Sensitivität von 100% und eine Spezifität von 70% bei der Beurteilung des postoperativen Hörvermögens.

Schlussfolgerungen:

Die bisherigen Ergebnisse zeigen, dass die direkte Ableitung vom Nervus cochlearis eine zuverlässige Beurteilung des Hörerhalts zu lässt. Dies soll nun weiter ausgebaut werden, um die Aussagekraft des intraoperativen Monitorings während der transtemporalen Akustikusneurinomexstirpation weiter zu verbessern.

Abstract

Direct Recording from Cochlear Nerve via a ­Ball-Electrode in Transtemporal Acoustic Neuroma Surgery

Background:

Intraoperative monitoring (IOM) of the cochlear nerve function during acoustic neuroma surgery is employed to assist in preserving hearing. So far, Auditory Brain­stem Response (ABR) is considered to be an optimal method for intraoperative monitoring in transtemporal approach. The aim of this study was to perform direct recording of the cochlear nerve action potential after resection of the tumor by using a ball-electrode and to evaluate the use of this method in predicting the postopera­tive hearing. The obtained data were compared to the simultaneous ABR results and to the postoperative hearing.

Materials and Methods:

In 2009, 38 patients have undergone acoustic Neuroma Surgery at the ENT University hospital, Wuerzburg. In 33 patients an intraoperative ABR as well as a direct measurement from the cochlear nerve using a ball electrode were performed. In 5 patients the postoperative hearing was predicted using the direct measurement at the cochlear nerve only.

Results:

The direct recording from the cochlear nerve gave very robust responses. Even in cases where ABR recording was not possible, the identification of clear cochlear nerve action potential could still be reached. Using the direct recordings from the cochlear nerve to predict the post operative hearing turned out to have a sensitivity of 100% and a specificity of 70%.

Conclusions:

These results show that intraoperative monitoring with direct recording from the cochlear nerve via a ball-electrode in transtemporal approaches offers a valuable method to predict the postoperative hearing. Further investigation will be made to provide additional information.

Schlüsselwörter

Vestibularisschwannom - Kugelelektrode - intraoperatives Monitoring - transtemporaler Zugang - Hörerhalt - BERA

Key words

Acoustic neuroma - ball-electrode - intraoperative monitoring - BERA

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