Changing the clinical course of glioma patients by preoperative motor mapping with navigated transcranial magnetic brain stimulation

Abstract

BackgroundMapping of the motor cortex by navigated transcranial magnetic stimulation (nTMS) can be used for preoperative planning in brain tumor patients. Just recently, it has been proven to actually change outcomes by increasing the rate of gross total resection (GTR) and by reducing the surgery-related rate of paresis significantly in cohorts of patients suffering from different entities of intracranial lesions. Yet, we also need data that shows whether these changes also lead to a changed clinical course, and can also be achieved specifically in high-grade glioma (HGG) patients.MethodsWe prospectively enrolled 70 patients with supratentorial motor eloquently located HGG undergoing preoperative nTMS (2010–2014) and matched these patients with 70 HGG patients who did not undergo preoperative nTMS (2007–2010).ResultsOn average, the overall size of the craniotomy was significantly smaller for nTMS patients when compared to the non-nTMS group (nTMS: 25.3 ± 9.7 cm2; non-nTMS: 30.8 ± 13.2 cm2; p = 0.0058). Furthermore, residual tumor tissue (nTMS: 34.3%; non-nTMS: 54.3%; p = 0.0172) and unexpected tumor residuals (nTMS: 15.7%; non-nTMS: 32.9%; p = 0.0180) were less frequent in nTMS patients. Regarding the further clinical course, median inpatient stay was 12 days for the nTMS and 14 days for the non-nTMS group (nTMS: CI 10.5 – 13.5 days; non-nTMS: CI 11.6 – 16.4 days; p = 0.0446). 60.0% of patients of the nTMS group and 54.3% of patients of the non-nTMS group were eligible for postoperative chemotherapy (OR 1.2630, CI 0.6458 – 2.4710, p = 0.4945), while 67.1% of nTMS patients and 48.6% of non-nTMS patients received radiotherapy (OR 2.1640, CI 1.0910 – 4.2910, p = 0.0261). Moreover, 3, 6, and 9 months survival was significantly better in the nTMS group (p = 0.0298, p = 0.0015, and p = 0.0167).ConclusionsWith the limitations of this study in mind, our data show that HGG patients might benefit from preoperative nTMS mapping.

Resection of Motor Eloquent Metastases Aided by Preoperative nTMS-Based Motor Maps—Comparison of Two Observational Cohorts

“…The EOR that we observed in this study is in accordance with other studies on the effect of mapping on EOR (2–4, 23–25). Studies have shown conclusively that IOM results in greater EOR (6, 23, 26); how the addition of preoperative mapping further improves EOR is not as obvious.…”

“…Similarly, having preoperative nTMS data allowed for limited craniotomy size because larger exposures simply for mapping purposes were not required (6). Prior comparisons between large cohorts of patients undergoing nTMS and non-nTMS (for various primary CNS pathologies including eloquent gliomas) were not able to show any significant difference in surgical time (2–4). We postulate that this difference is due to the infiltrative nature of gliomas—in these cases, surgeons depend on IOM to give the most complete resection of abnormal tissue within eloquent cortex.…”

“…Variations in tumor location, aggressiveness, and prognosis mean that a novel presurgical technique must undergo extensive testing in a large cohort before it can be considered effective. nTMS has demonstrated benefit in the surgical treatment of eloquent supratentorial primary central nervous system (CNS) lesions (2–4). It is as yet unclear whether similar benefit exists for the management of eloquent supratentorial metastatic lesions (2–4).…”

“…Although the positive impact of nTMS on surgical indication, approach planning, and functional outcome has been shown for gliomas, similar effects have yet to be demonstrated in the management of metastatic lesions (2–4). This multicenter study aims to compare the surgical outcome of patients with motor eloquent metastatic lesions who received preoperative nTMS-based motor mapping with those that did not.…”

“…Another technique, navigated transcranial magnetic stimulation (nTMS), which uses magnetic pulses to activate small regions of cortex, has demonstrated the ability to map the motor system in the preoperative setting. For supratentorial lesions located in motor eloquent areas, especially gliomas, three prior studies have demonstrated improvement in outcomes when preoperative functional mapping of motor areas is also performed by nTMS (2–4). …”