gms | German Medical Science

55. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e. V. (DGNC)
1. Joint Meeting mit der Ungarischen Gesellschaft für Neurochirurgie

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

25. bis 28.04.2004, Köln

Morphometric evaluation and prognostic factors for hearing preservation in surgery of acoustic neurinoma

Morphometrische Analyse und prognostische Faktoren zur hörerhaltenden Chirurgie von Akustikus-Neurinomen

Meeting Abstract

  • corresponding author Ramin Naraghi - Neurochirurgische Klinik, Universität Erlangen-Nürnberg, Erlangen
  • P. Lohse - Neurochirurgische Klinik, Universität Erlangen-Nürnberg, Erlangen
  • B. Tomandl - Abteilung für Neuroradiologie der Neurochirurgischen Klinik, Universität Erlangen-Nürnberg, Erlangen
  • B. Bischoff - Neurochirurgische Klinik, Universität Erlangen-Nürnberg, Erlangen
  • R. Fahlbusch - Neurochirurgische Klinik, Universität Erlangen-Nürnberg, Erlangen

Deutsche Gesellschaft für Neurochirurgie. Ungarische Gesellschaft für Neurochirurgie. 55. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), 1. Joint Meeting mit der Ungarischen Gesellschaft für Neurochirurgie. Köln, 25.-28.04.2004. Düsseldorf, Köln: German Medical Science; 2004. DocMO.11.02

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/dgnc2004/04dgnc0108.shtml

Veröffentlicht: 23. April 2004

© 2004 Naraghi et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

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Objective

MRT Morphometric evaluations of the relationship of the labyrinth to the posterior surface of the petrous bone for preoperative planning and preservation of hearing are presented and prognostic factors are determined.

Methods

Preoperative and postoperative high resolution MRI studies (T2, T1-cotrast enhanced axial and coronal) were performed in a prospective series of 51 patients with acoustic neurinoma and hearing. An axis running perpendicular from the fundus of the meatus to the posterior surface of the petrouse bone was introduced to which relevant distances (D1-D8) were defined and measured for a save opening of the internal auditory canal. Intrameateal and extra meatal tumor volume was calculated. Pure tone audiogram and speech discrimination determined the hearing function. Tumor volumes and distances were correlated to the pre and postoperative hearing. Pearson correlation and logistic regression were applied for statistics.

Results

Knowing the distances it was possible to open the internal auditory meatus gaining a complete view. No intraoperative penetration into the labyrinth by applying the measured data, was noticed, which was approved by the postoperative MRT examinations. For all cases with the small intrameatal tumors up to 1ml (up to 11 mm diameter), hearing preservation at the preoperative level was achieved. We attribute this to the elimination of labyrinth penetration. Tumors ranging 1-4 ml (11-18 mm diameter) have in 50%, sizes between 4-8 ml (18-23 mm diameter) have in 40% and tumor sizes over 8 ml (>23 mm) in 18% preserved hearing. The risk for postoperative hearing loss is in small tumors (< 1ml) below 20%, for tumors sizing 1-4 ml (11-18 mm) is 20-40% and for 4-8 ml (18-23 mm) 40-70% and for those over 8 ml (>23 mm) is above 70%. Ventral tumor extension above 5.5 mm results always in postoperative hearig loss.

Conclusions

Preoperative morphometric evaluation avoids any injury to the labyrinth and during opening of the internal meatus, which is one of the factors for postoperative hearing loss. We found clear evidence for a major influence of the tumor volume and the ventral tumor extension on postoperative hearing function. These enable the patient and the surgeon to find an improved individually adapted strategy of treatment.