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Updated: May 5, 2026

Thinned-skull Cortical Window Technique for In Vivo Optical Coherence Tomography Imaging
Published on: November 19, 2012
Protecting vision with intraoperative visual evoked potentials and tractography in transcortical brain tumor surgery
Ioannis Mavridis1, George Tokas1, Efstratios-Stylianos Pyrgelis2
1Department of Neurosurgery, School of Medicine, Democritus University of Thrace; University General Hospital of Alexandroupolis, Alexandroupolis, Greece.
Objective:
Intraoperative neuromonitoring (IONM) is nowadays a gold standard during brain tumor resections, but visual function mapping is less frequently performed in clinical practice. This article aims to report two transcortical brain tumor surgery cases affecting optic radiation, where the application of intraoperative visual evoked potentials (VEP) combined with tractography was beneficial to protect the patients' vision.
Methods:
Two patients with brain tumors compressing the left posterior visual pathways underwent surgery under general anesthesia using IONM and VEP with neurologic improvement and preservation of vision.
Results:
VEP is beneficial in the surgery of intra-axial lesions affecting the posterior visual pathways (optic radiation, visual cortex) and parasellar lesions involving the anterior visual pathways (chiasm). They can also be effectively combined with other mapping methods such as tractography.
Conclusions:
According to our experience, IONM with VEPs and neuronavigation with tractography protect visual function in transcortical approaches to resecting tumors near the optic radiation and should be considered a standard monitoring method for such operations.

