Dual-Task nTMS Mapping to Visualize the Cortico-Subcortical Language Network and Capture Postoperative Outcome-A Patient Series in Neurosurgery

Ann-Katrin Ohlerth; Roelien Bastiaanse; Lyndsey Nickels; Beate Neu; Wei Zhang; Sebastian Ille; Nico Sollmann; Sandro M Krieg

doi:10.3389/fonc.2021.788122

Dual-Task nTMS Mapping to Visualize the Cortico-Subcortical Language Network and Capture Postoperative Outcome-A Patient Series in Neurosurgery

Front Oncol. 2022 Jan 21:11:788122. doi: 10.3389/fonc.2021.788122. eCollection 2021.

Authors

Ann-Katrin Ohlerth^{1

2}, Roelien Bastiaanse³, Lyndsey Nickels⁴, Beate Neu⁵, Wei Zhang⁵, Sebastian Ille⁵, Nico Sollmann^{6

7

8}, Sandro M Krieg^{5

8}

Affiliations

¹ Center for Language and Cognition Groningen, Groningen, Netherlands.
² International Doctorate in Experimental Approaches to Language and Brain (IDEALAB, Universities of Groningen, Potsdam, Newcastle, and Macquarie University), Sydney, NSW, Australia.
³ Center for Language and Brain, Higher School of Economics, National Research University, Moscow, Russia.
⁴ School of Psychological Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia.
⁵ Department of Neurosurgery, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
⁶ Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Ulm, Germany.
⁷ Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
⁸ TUM-Neuroimaging Center, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.

Abstract

Background: Perioperative assessment of language function in brain tumor patients commonly relies on administration of object naming during stimulation mapping. Ample research, however, points to the benefit of adding verb tasks to the testing paradigm in order to delineate and preserve postoperative language function more comprehensively. This research uses a case series approach to explore the feasibility and added value of a dual-task protocol that includes both a noun task (object naming) and a verb task (action naming) in perioperative delineation of language functions.

Materials and methods: Seven neurosurgical cases underwent perioperative language assessment with both object and action naming. This entailed preoperative baseline testing, preoperative stimulation mapping with navigated Transcranial Magnetic Stimulation (nTMS) with subsequent white matter visualization, intraoperative mapping with Direct Electrical Stimulation (DES) in 4 cases, and postoperative imaging and examination of language change.

Results: We observed a divergent pattern of language organization and decline between cases who showed lesions close to the delineated language network and hence underwent DES mapping, and those that did not. The latter displayed no new impairment postoperatively consistent with an unharmed network for the neural circuits of both object and action naming. For the cases who underwent DES, on the other hand, a higher sensitivity was found for action naming over object naming. Firstly, action naming preferentially predicted the overall language state compared to aphasia batteries. Secondly, it more accurately predicted intraoperative positive language areas as revealed by DES. Thirdly, double dissociations between postoperatively unimpaired object naming and impaired action naming and vice versa indicate segregated skills and neural representation for noun versus verb processing, especially in the ventral stream. Overlaying postoperative imaging with object and action naming networks revealed that dual-task nTMS mapping can explain the drop in performance in those cases where the network appeared in proximity to the resection cavity.

Conclusion: Using a dual-task protocol for visualization of cortical and subcortical language areas through nTMS mapping proved to be able to capture network-to-deficit relations in our case series. Ultimately, adding action naming to clinical nTMS and DES mapping may help prevent postoperative deficits of this seemingly segregated skill.

Keywords: action naming; case series; direct electrical stimulation; language mapping; navigated transcranial magnetic stimulation; object naming; postoperative language state.