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61st Annual Meeting of the German Society of Neurosurgery (DGNC) as part of the Neurowoche 2010
Joint Meeting with the Brazilian Society of Neurosurgery on the 20 September 2010

German Society of Neurosurgery (DGNC)

21 - 25 September 2010, Mannheim

Visually evoked potentials during the endonasal endoscopic approach for anterior skull base tumors

Meeting Abstract

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  • Hi-Jae Heiroth - Klinik für Neurochirurgie, Heinrich-Heine-Universität Düsseldorf, Germany
  • Hans-Jakob Steiger - Klinik für Neurochirurgie, Heinrich-Heine-Universität Düsseldorf, Germany
  • Daniel Hänggi - Klinik für Neurochirurgie, Heinrich-Heine-Universität Düsseldorf, Germany

Deutsche Gesellschaft für Neurochirurgie. 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010. Mannheim, 21.-25.09.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. DocP1752

doi: 10.3205/10dgnc223, urn:nbn:de:0183-10dgnc2237

Published: September 16, 2010

© 2010 Heiroth et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: One option of approaching lesions within the anterior skull is the extended endonasal endoscopic one. The identification and protection of the optic nerve is one of the crucial anatomic demands within this approach. The goal of the present study was to analyze the efficacy of intraoperative monitoring (IOM) of visually evoked potentials (VEP) in patients treated for anterior skull base tumors via the expanded endonasal approach.

Methods: Within the present pilot study, ten patients with anterior skull base tumors close to the anterior optic system were included. All patients were treated with the extended endonasal endoscopic approach. VEP were continuously recorded (NeuroExplorer 4.3 (2009) INOMED, Teningen, Germany) using light - emitting - diode (LED) - goggles, sending flash-lights with a stimulation frequency of 1.1 Hz, pulse width 1000 µs, stimulation current varied from 15–30 mA. Patients were anesthetized by intravenous anesthesia (TIVA) during surgery. IOM was measured and scaled according to surgical steps.

Results: In all patients intraoperative recordings of VEP were possible to be analyzed. In all patients VEP showed a prominent positive peak with a latency of about 100ms (P100) in relation to the operative procedure. In addition some patients showed a small peak with a latency between 40–55 ms and a negative peak around 70–75 ms (P70). There were no significant differences between the left and right eye. Artifacts were seen during drilling and coagulating and these were always bilateral.

Clinically one patient suffered from preoperative visual deficits which recovered fully after the operation. All other nine patients did not have any visual deficit before or after surgery.

Conclusions: The present study shows that IOM with VEP could be a useful monitoring tool in patients treated for anterior skull base tumors via the extended endonasal endoscopic approach but susceptible to artifacts. Based on our experience it is necessary to develop the technique in further studies.