AUTHOR=Neville Iuri Santana , Gomes dos Santos Alexandra , Almeida Cesar Cimonari , Hayashi Cintya Yukie , Solla Davi Jorge Fontoura , Galhardoni Ricardo , de Andrade Daniel Ciampi , Brunoni Andre Russowsky , Teixeira Manoel Jacobsen , Paiva Wellingson Silva 

TITLE=Evaluation of Changes in Preoperative Cortical Excitability by Navigated Transcranial Magnetic Stimulation in Patients With Brain Tumor

JOURNAL=Frontiers in Neurology

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2020.582262

DOI=10.3389/fneur.2020.582262

ISSN=1664-2295

ABSTRACT=<p><bold>Background:</bold> This prospective study aimed to evaluate the cortical excitability (CE) of patients with brain tumors surrounding or directly involving the <bold>corticospinal tract</bold> (CST) using navigated transcranial magnetic stimulation (nTMS).</p><p><bold>Methods:</bold> We recruited 40 patients with a single brain tumor surrounding or directly involving the CST as well as 82 age- and sex-matched healthy controls. The patients underwent standard nTMS and CE evaluations. Single and paired pulses were applied to the primary motor area (M1) of both affected and unaffected cerebral hemispheres 1 week before surgery. The CE parameters included resting motor threshold (RMT), motor evoked potential (MEP) ratio for 140 and 120% stimulus (MEP 140/120 ratio), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF). Motor outcome was evaluated on hospital discharge and on 30-day and 90-day postoperative follow-up.</p><p><bold>Results:</bold> In the affected hemispheres of patients, SICI and ICF were significantly higher than in the unaffected hemispheres (<italic>p</italic>=0.002 and <bold><italic>p</italic></bold>=0.009, respectively). The 140/120 MEP ratio of patients' unaffected hemispheres was lower than that in controls (<italic>p</italic>=0.001). Patients with glioblastomas (GBM) had a higher interhemispheric RMT ratio than patients with grade II and III gliomas (<bold><italic>p</italic></bold> = 0.018). A weak correlation was observed among the RMT ratio and the preoperative motor score (<italic>R</italic><sup>2</sup> = 0.118, <italic>p</italic> = 0.017) and the 90-day follow-up (<bold><italic>R</italic></bold><sup><bold>2</bold></sup> = 0.227, <italic>p</italic> = 0.016).</p><p><bold>Conclusion:</bold> Using preoperative nTMS, we found that brain hemispheres affected by tumors had abnormal CE and that patients with GBM had a distinct pattern of CE. These findings suggest that tumor biological behavior might play a role in CE changes.</p>