gms | German Medical Science

60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)
Joint Meeting mit den Benelux-Ländern und Bulgarien

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

24. - 27.05.2009, Münster

Schwannoma of the intermediate nerve

Meeting Abstract

  • C. Scheller - Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale
  • J. Rachinger - Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale
  • J. Prell - Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale
  • S. Rampp - Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale
  • C. Strauss - Klinik und Poliklinik für Neurochirurgie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale

Deutsche Gesellschaft für Neurochirurgie. 60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit den Benelux-Ländern und Bulgarien. Münster, 24.-27.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. DocP08-05

DOI: 10.3205/09dgnc333, URN: urn:nbn:de:0183-09dgnc3339

Veröffentlicht: 20. Mai 2009

© 2009 Scheller 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 vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Objective: Intermediate nerve schwannomas are rarely addressed in the literature. So far, only three case reports have been published. We present two cases with clinical symptoms, electrophysiological characteristics, radiological and intraoperative findings, and clinical outcome.

Methods: A 29-year-old and a 35-year-old man presented with tinnitus and progressive hearing loss. According to the House-Brackmann classification, facial nerve function was classified as grade I and grade III, respectively. Magnetic resonance imaging (MRI) revealed a tumor of the cerebello-pontine angle extending up to the geniculate ganglion and along the course of the superficial petrosal nerve. CT scan showed pathological enlargement of the facial nerve canal. In the second case MRI showed a mass lesion of the cerebello-pontine angle with contact to the brain stem and extension into the internal acoustic and further into the facial nerve canal. In both cases microsurgery was performed via a retrosigmoid approach.

Results: Intraoperative and electrophysiological findings clearly indicated the intermediate nerve as the site of tumor origin in both cases. Preoperative electromyography revealed fibrillation potentials in the orbicularis oris and nasalis muscle as an indication of a partial denervation of these muscles because of a damage to the supposed motor fibers of the intermediate nerve. Direct intermediate nerve stimulation during surgery resulted in EMG activity only in the orbicularis oris muscle with longer latencies and smaller amplitudes as compared to stimulation of the facial nerve.

Conclusions: Facial nerve schwannomas represent 2–3% of the tumors of the cerebello-pontine angle. It seems possible to detect the intermediate nerve during cerebello-pontine angle surgery using selective direct nerve stimulation. This observation suggests that more intermediate nerve schwannomas may be identified as tumor origin by detailed intraoperative electrophysiological examination. In addition, these electrophysiological findings suggest that the intermediate nerve may carry motor fibers for the orbicularis oris muscle. Furthermore, damage to the intermediate nerve might be the explanation for the frequent postoperatively recognized facial nerve weakness predominantly of the orbicularis oris muscle.