Transcranial magnetic stimulation (TMS) seeded tractography provides superior prediction of eloquence compared to anatomic seeded tractography

Matthew Muir; Sarah Prinsloo; Hayley Michener; Arya Shetty; Dhiego Chaves de Almeida Bastos; Jeffrey Traylor; Chibawanye Ene; Sudhakar Tummala; Vinodh A Kumar; Sujit S Prabhu

doi:10.1093/noajnl/vdac126

Transcranial magnetic stimulation (TMS) seeded tractography provides superior prediction of eloquence compared to anatomic seeded tractography

Neurooncol Adv. 2022 Sep 15;4(1):vdac126. doi: 10.1093/noajnl/vdac126. eCollection 2022 Jan-Dec.

Affiliations

¹ Department of Neurosurgery, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA.
² Department of Neurosurgery, Cleveland Clinic, Cleveland, Ohio, USA.
³ Department of Neurological Surgery, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
⁴ Department of Neuro-Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas,USA.
⁵ Department of Neuroradiology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA.

Abstract

Background: For patients with brain tumors, maximizing the extent of resection while minimizing postoperative neurological morbidity requires accurate preoperative identification of eloquent structures. Recent studies have provided evidence that anatomy may not always predict eloquence. In this study, we directly compare transcranial magnetic stimulation (TMS) data combined with tractography to traditional anatomic grading criteria for predicting permanent deficits in patients with motor eloquent gliomas.

Methods: We selected a cohort of 42 glioma patients with perirolandic tumors who underwent preoperative TMS mapping with subsequent resection and intraoperative mapping. We collected clinical outcome data from their chart with the primary outcome being new or worsened motor deficit present at 3 month follow up, termed "permanent deficit". We overlayed the postoperative resection cavity onto the preoperative MRI containing preoperative imaging features.

Results: Almost half of the patients showed TMS positive points significantly displaced from the precentral gyrus, indicating tumor induced neuroplasticity. In multivariate regression, resection of TMS points was significantly predictive of permanent deficits while the resection of the precentral gyrus was not. TMS tractography showed significantly greater predictive value for permanent deficits compared to anatomic tractography, regardless of the fractional anisotropic (FA) threshold. For the best performing FA threshold of each modality, TMS tractography provided both higher positive and negative predictive value for identifying true nonresectable, eloquent cortical and subcortical structures.

Conclusion: TMS has emerged as a preoperative mapping modality capable of capturing tumor induced plastic reorganization, challenging traditional presurgical imaging modalities.

Keywords: anatomy; glioma; neurological deficit; tractography; transcranial magnetic stimulation.