gms | German Medical Science

65th Annual Meeting of the German Society of Neurosurgery (DGNC)

German Society of Neurosurgery (DGNC)

11 - 14 May 2014, Dresden

Perilesional edema of the inner capsule deteriorates nTMS- and DTI-based fiber tracking results

Meeting Abstract

  • Carolin Weiß - Klinik für Allgmeine Neurochirurgie, Universität zu Köln; Max-Planck-Institut für Neurologische Forschung, Köln
  • Irada Tursunova - Klinik für Allgmeine Neurochirurgie, Universität zu Köln
  • Volker Neuschmelting - Klinik für Allgmeine Neurochirurgie, Universität zu Köln
  • Charlotte Nettekoven - Max-Planck-Institut für Neurologische Forschung, Köln
  • Andrea Faymonville - Klinik für Allgmeine Neurochirurgie, Universität zu Köln
  • Gabriele Stoffels - Institut für Neurowissenschaften und Medizin, Forschungszentrum Jülich
  • Anca Oros-Peusquens - Institut für Neurowissenschaften und Medizin, Forschungszentrum Jülich
  • Christian Grefkes - Max-Planck-Institut für Neurologische Forschung, Köln; Klinik und Poliklinik für Neurologie, Universität zu Köln
  • Roland Goldbrunner - Klinik für Allgmeine Neurochirurgie, Universität zu Köln

Deutsche Gesellschaft für Neurochirurgie. 65. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC). Dresden, 11.-14.05.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocMI.19.03

doi: 10.3205/14dgnc389, urn:nbn:de:0183-14dgnc3891

Published: May 13, 2014

© 2014 Weiß 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

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Objective: Diffusion tensor imaging (DTI)-based fiber tracking is a commonly used method for function-preserving surgery of gliomas located within the white matter, e.g., adjacent to the corticospinal tract (CST). Recently, the results of navigated transcranial magnetic stimulation (nTMS) have been used to delineate the cortical seed ROI corresponding to M1. However, in some cases, nTMS-based fiber tracking of the CST remains challenging. Since DTI is highly susceptible for T2-alterations, tumor associated edema may confound fiber tracking of the CST.

Method: We analyzed nTMS-based fiber tracking of body-area-specific CST in 31 patients with intracranial tumors. NTMS was performed using eXimia 4.2. MEPs were recorded by surface electrodes from the hand (APB), the foot (plantar muscle) and the tongue, whenever clinically relevant (82 body areas). To control for unspecific biases, hand mapping was performed on the contralateral side, also. NTMS-maps were exported in DICOM format, integrated in the iPlan-sofiber trackingware and used as seed ROIs. A second ROI was placed on pontine level. The fiber tracking results were checked for plausibility according to anatomical considerations (course on level of inner capsule and towards the brainstem). To investigate influencing factors, tumor vol., tumor edema vol. and edema within the inner capsule were analyzed.

Results: On the contralateral side, all trackings of the CST showed plausible results. However, on the tumor side, the rate of plausible fiber trackings was 88% overall, with highly plausible results for the hand, whereas tracking the foot- and tongue-associated CST was more challenging (hand: 97%; foot: 84%; tongue: 77%). The contrast-enhancing tumor vol. (p=.61) and the vol. of the T2-hyperintense perifocal edema (p=.21) did not influence the plausibility of the tracking results. However, edema within the inner capsule deteriorated the fiber tracking results remarkably (p=.02) and may serve as a, however poorly specific (35%) predictor for troubles with tracking the CST (sensitivity: 65%).

Conclusions: NTMS-based fiber tracking of the CST offers valuable informations for surgery planning in the majority of cases. Tracking the CST of the hand proved to be less challenging than CTS of the foot or even the tongue. However, tumor-associated edema within the inner capsule deteriorates the fiber tracking results. In such cases, the results should be interpreted with caution, especially when using them for surgery planning.