gms | German Medical Science

62nd Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Polish Society of Neurosurgeons (PNCH)

German Society of Neurosurgery (DGNC)

7 - 11 May 2011, Hamburg

The intermediate nerve and its contiguous structures in the cerebellopontine angle – An anatomical study

Meeting Abstract

  • A. Alfieri - Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Halle
  • E. Peschke - Institut für Anatomie und Zellbiologie, Martin-Luther-Universität Halle-Wittenberg
  • J. Fleischhammer - Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Halle; Institut für Anatomie und Zellbiologie, Martin-Luther-Universität Halle-Wittenberg
  • C. Strauss - Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Halle

Deutsche Gesellschaft für Neurochirurgie. Polnische Gesellschaft für Neurochirurgen. 62. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Polnischen Gesellschaft für Neurochirurgen (PNCH). Hamburg, 07.-11.05.2011. Düsseldorf: German Medical Science GMS Publishing House; 2011. DocP 071

DOI: 10.3205/11dgnc292, URN: urn:nbn:de:0183-11dgnc2921

Published: April 28, 2011

© 2011 Alfieri et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

Text

Objective: In cerebellopontine angle surgery, the intermediate nerve (IN) is an often neglected and underestimated anatomical structure. The goal of our study was to analyze the large variations in the course of the IN and its anastomoses and its anatomical relationship to the facial and the vestibulocochlear nerve.

Methods: Eight human subjects and thirteen isolated human brains were investigated with an operating microscope. Morphometric and topographic data regarding the root-entry-zone, the bundles, the vascular relationships, and complementary anatomical features of the IN were collected. Accordingly, the anatomical relation of the intermediate nerve to the facial and the vestibulocochlear nerves in the cerebellopontine angle was determined.

Results: The following variants of exit-root-zone were documented: directly from the brain stem in 31%, together with the vestibulo-cochlear nerve in 31%, from the facial nerve in 13%, and from both the facial and cochlear in 25% of the specimens. The number intermediate nerve roots varied from 1 to 5 (median 2.94 ± 1.12). The length of the cisternal segment of the intermediate nerve from the brainstem to the porus was a mean of 36.93 ± 3.08 mm. In the dissected cadavers the intermediate nerve reached the facial nerve 1.44 mm proximal to the internal acoustic meatus (SD 3.33 mm). The diameter of the IN reached a mean of 0.7 ± 0.24 mm. In 80% of cases, a vein between the root exit zones was documented.

Conclusions: The anatomical results showed a large variability regarding the location of the exit from the brain stem of the IN with a constantly observed merging with the facial nerve in proximity of the internal acoustic meatus. Moreover, the described vein may serve as orientation landmark.