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Acta Neurochirurgica

, Volume 156, Issue 2, pp 403–408 | Cite as

The relationship between nervus intermedius anatomy, ultrastructure, electrophysiology, and clinical function. Usefulness in cerebellopontine microsurgery

  • Alex Alfieri
  • Stefan Rampp
  • Christian Strauss
  • Julius Fleischhammer
  • Jens Rachinger
  • Christian Scheller
  • Julian Prell
Clinical Article - Neurosurgical Anatomy

Abstract

Background

Although previous studies have described the clinical features of the nervus intermedius (NI), no attempt has yet been made to describe the relationship between the ultrastructural and electrophysiological characteristics of the nervus intermedius and its motor competence.

Objective

In this study, we analyzed the intraoperative electrophysiological response obtained during vestibular schwannoma surgery. The ultrastructure was studied using electron microscopy.

Materials and Methods

Thirty-six consecutive patients underwent microsurgery for vestibular schwannoma with cerebellopontine angle tumors. The patients were extensively monitored intraoperatively. Selective stimulation of the nervus intermedius was attempted in all cases. The patients were then examined postoperatively and followed for a minimum of 1 year. Forty-three isolated human brainstems were analyzed to collect the ultrastructural NI data.

Results

We found a correlation between the NI motor responses in the perinasal and perioral regions and the ultrastructure characteristics, with few (0.5 %) but large myelinated motor fibers (diameters >12 μm). Both characteristics are consistent with the clinical observation of transient weakness of the levator anguli oris muscle. These observations indicate a relationship between the intraoperative electrophysiological identification of the NI nervus intermedius and its clinical and ultrastructural characteristics.

Conclusions

Identifying the NI in the deformed anatomy of tumors could provide a fixed landmark during cerebellopontine surgery and help prevent damage of the facial nerve.

Keywords

Facial nerve Acoustic neuroma Vestibular schwannoma Cerebellopontine surgery Intraoperative neuromonitoring Electron microscopy 

Notes

Acknowledgments

Drs. Alfieri and Rampp contributed equally to the study. We are grateful to Mr. Heine and Dr. Litvak for their remarkable contribution to this study. The patient authorized the publication of the images.

Conflicts of interest

None.

Funding

Wilhelm Roux Foundation, Martin Luther University Halle-Wittenberg, Germany

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Copyright information

© Springer-Verlag Wien 2013

Authors and Affiliations

  • Alex Alfieri
    • 1
  • Stefan Rampp
    • 2
  • Christian Strauss
    • 2
  • Julius Fleischhammer
    • 2
  • Jens Rachinger
    • 2
  • Christian Scheller
    • 2
  • Julian Prell
    • 2
  1. 1.Neurosurgery and Spinal SurgeryNeuruppinGermany
  2. 2.Department of NeurosurgeryMartin Luther University Halle-WittenbergHalle (Saale)Germany

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