Navigated Brain Stimulation (NBS) by Nexstim, is the only CE marked and FDA cleared noninvasive solution to presurgical mapping of the motor cortex. The NBS System 5 adds navigation to transcranial magnetic stimulation (nTMS), creating a precise map of the eloquent cortex superimposed on a patient specific MRI. NBS accurately locates the stimulating electric field (E-field) in the cortex, with the proven accuracy of direct cortical stimulation (DCS)1.
In a recent study of 250 consecutive patients, presurgical mapping with Navigated Brain Stimulation enabled a more aggressive surgical strategy in more the 75% of the cases. The same study using navigated TMS (nTMS) disproved suspected involvement of primary motor cortex in over 25% of the cases, expanding surgical indication by 14.8%. Concluding that the integration of nTMS into the surgical workflow crucially improves pre-operative planning, patient counseling, and surgical procedures. Leading to longer progression-free survival rates and better neurological outcomes by expanding the indications and extent of resection.3
The Difference is Accuracy
Noninvasive Navigated Brain Stimulation has been proven to identify the motor eloquent cortex with +/- 2mm of direct cortical stimulation.1
Preserving what is Vital
Multiple clinical studies have proven that Navigated Brain Stimulation, as an adjunct to direct cortical stimulation, results in a 35% increase or greater, in the rate of gross total resection.2,3
Introduction: Mapping 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.
Methods: We 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).
Results: Statistically significant difference in craniotomy dimensions. (Smaller in the TMS group). Significantly less residual tumor and fewer unexpected residual tumors in TMS group. (Residual Tumor: 34.3% v 54.3% NBS group v non-NBS; Unexpected Residual Tumor: 15.7% v 32.9% NBS group v non-NBS group). Significantly shorted length of stay in the TMS group.( 12 days v 14 days for NBS group v non-NBS group). A significantly higher proportion of TMS group patients were eligible for post-operative radiotherapy, 67.1% v.48.6%
Conclusion: With the limitations of this study in mind, our data show that HGG patients might benefit from preoperative nTMS mapping.
Publication: BMC Cancer (2015) 15:231 doi:10.1186/s12885-015-1258-1
Introduction: Neurological and oncological outcomes of motor eloquent brain-tumor patients depend upon the ability to localize functional areas and the respective proposed therapy. We set out to determine whether the use of navigated transcranial magnetic stimulation (nTMS) had an impact on treatment and outcome in patients with brain tumors in motor eloquent locations.
Methods: We enrolled 250 consecutive patients and compared their functional and oncological outcomes to a matched pre-nTMS control group (n = 115).
Results: nTMS mapping results disproved suspected involvement of primary motor cortex in 25.1% of cases, expanded surgical indication in 14.8%, and led to planning of more extensive resection in 35.2% of cases and more restrictive resection in 3.5%. In comparison with the control group, the rate of gross total resections increased significantly from 42% to 59% (P < .05). Progression-free-survival for low grade glioma was significantly better in the nTMS group at 22.4 months than in control group at 15.4 months (P < .05). Integration of nTMS led to a nonsignificant change of postoperative deficits from 8.5% in the control group to 6.1% in the nTMS group.
Conclusions: nTMS provides crucial data for preoperative planning and surgical resection of tumors involving essential motor areas. Expanding surgical indications and extent of resection based on nTMS enables more patients to undergo surgery and might lead to better neurological outcomes and higher survival rates in brain tumor patients. The impact of this study should go far beyond the neurosurgical community because it could fundamentally improve treatment and outcome, and its results will likely change clinical practice.
Publication: Neuro Oncol. 2014 Jun 12. pii: nou110. PMID: 24923875 http://www.ncbi.nlm.nih.gov/pubmed/24923875
Introduction: Because navigated transcranial magnetic stimulation (nTMS) is increasingly used in neurosurgical research, interpretation of its results is of utmost importance.
Objective: To evaluate the test-retest reliability of nTMS.
Methods: Twelve healthy participants underwent nTMS at 2 different sessions separated by 10.3 ± 9.6 days. Investigated parameters included resting motor thresholds, hotspots, and centers of gravity calculated for the first dorsal interosseous, abductor pollicis brevis, extensor digitorum, tibial anterior, and abductor hallucis muscles.
Results: Excellent reliability of resting motor thresholds was observed. Hotspots and centers of gravity showed moderate to excellent repeatability along the anteroposterior axis (intraclass correlation coefficient, 0.54-0.89), whereas the x coordinate presented mainly poor to moderate stability (intraclass correlation coefficient, 0.11-0.89). Movement of centers of gravity over sessions was 0.57 ± 0.32 cm, and hotspots laid 0.79 ± 0.47 cm apart. Calculation of coefficient of variation revealed high reliability of investigated parameters in upper extremities; in lower extremity muscles, high variation across sessions was observed.
Conclusion: nTMS can be considered a reliable tool, thus opening new fields of noninvasive investigations in neurosurgery. The results presented here should be considered in the interpretation of individual nTMS results.
Publication: Neurosurgery Neurosurgery. 2014 Mar;10 Suppl 1:51-5; discussion 55-6. doi: 10.1227/NEU.0000000000000075. http://www.ncbi.nlm.nih.gov/pubmed/23842557
Introduction: Navigated transcranial magnetic stimulation (nTMS) has been proven to influence surgical indication and planning. Yet there is still no clear evidence how these additional preoperative functional data influence the clinical course and outcome. Thus, this study aimed to compare patients with motor eloquently located supratentorial lesions investigated with or without preoperative nTMS in terms of clinical outcome parameters.
Methods: A prospectively enrolled cohort of 100 patients with supratentorial lesions located in motor eloquent areas was investigated by preoperative nTMS (2010–2013) and matched with a control of 100 patients who were operated on without nTMS data (2006–2010) by a matched pair analysis.
Results: Patients in the nTMS group showed a significantly lower rate of residual tumor on postoperative MRI (OR 0.3828; 95% CI 0.2062–0.7107). Twelve percent of patients in the nTMS and 1% of patients in the non-nTMS group improved while 75% and 81% of the nTMS and non-nTMS groups, respectively, remained unchanged and 13% and 18% of patients in the nTMS and non-nTMS groups, respectively, deteriorated in postoperative motor function on long-term follow-up (P = .0057). Moreover, the nTMS group showed smaller craniotomies (nTMS 22.4 ± 8.3 cm2; non-nTMS 26.7 ± 11.3 cm2; P = .0023).
Conclusions: This work increases the level of evidence for preoperative motor mapping by nTMS for rolandic lesions in a group comparison study. We therefore strongly advocate nTMS to become increasingly used for these lesions. However, a randomized trial on the comparison with the gold standard of intraoperative mapping seems mandatory.
Publication: Neuro Oncol. 2014 Feb 9. http://neuro-oncology.oxfordjournals.org/content/early/2014/02/08/neuonc.nou007.abstract
OBJECT: Navigated transcranial magnetic stimulation (nTMS) is a novel technology in the field of neurosurgery for noninvasive delineation of cortical functional topography. This study addresses the spatial accuracy and clinical usefulness of nTMS in brain tumor surgery in or near the motor cortex based on a systematic review of observational studies.
METHODS: A systematic search retrieved 11 reports published up to October 2012 in which adult patients were examined with nTMS prior to surgery. Quality criteria consisted of documentation of the influence of nTMS brain mapping on clinical decision making in a standardized prospective manner and/or performance of intraoperative direct electrical stimulation (DES) and comparison with nTMS results. Cross-observational assessment of nTMS accuracy was established by calculating a weighted mean distance between nTMS and DES.
RESULTS: All studies reviewed in this article concluded that nTMS correlated well with the "gold standard" of DES. The mean distance between motor cortex identified on nTMS and DES by using the mean distance in 81 patients described in 6 quantitatively evaluated studies was 6.18 mm. The nTMS results changed the surgical strategy based on anatomical imaging alone in 25.3% of all patients, based on the data obtained in 87 patients in 2 studies.
CONCLUSIONS: The nTMS technique spatially correlates well with the gold standard of DES. Its functional information benefits surgical decision making and changes the treatment strategy in one-fourth of cases.
Publication:Neurosurg Focus. 2013 Apr;34(4):E3. doi: 10.3171/2013.1.FOCUS133.
Abstract: Preoperative brain mapping is vital to improve the outcome of patients with tumors located in eloquent areas. While functional magnetic resonance imaging (fMRI) remains the most commonly used preoperative mapping technique, navigated transcranial magnetic stimulation (nTMS) has recently been proposed as a new preoperative method for the clinical and surgical management of such patients. This study aims at evaluating the impact of nTMS as a routine examination and its ultimate contribution to patient outcome. We performed a preliminary prospective study on eight patients harboring a cerebral lesion in eloquent motor areas. Each patient underwent preoperative cortical brain mapping via both fMRI and nTMS; then, we assessed the reliability of both methods by comparing them with intraoperative mapping by direct cortical stimulation (DCS). This study suggests that nTMS was more accurate than fMRI in detecting the true cortical motor area when compared with DCS data, with a mean of deviation ± confidence interval (CI) of 8.47 ± 4.6 mm between nTMS and DCS and of 12.9 ± 5.7 mm between fMRI and DCS (p < 0.05). The results indicated that within the limits of our statistical sample, nTMS was found to be a useful, reliable, and non-invasive option for preoperative planning as well as for the identification of the motor strip; in addition, it usually has short processing times and is very well tolerated by patients, thereby increasing their compliance and possibly improving surgical outcome.
Publication: Neurol Sci. 2013 Sep;34(9):1551-7. doi: 10.1007/s10072-012-1283-7. Epub 2012 Dec 25.PMID:23266868 http://www.ncbi.nlm.nih.gov/pubmed/23266868
Abstract: Navigated transcranial magnetic stimulation (nTMS) is a novel tool for preoperative functional mapping. It detects eloquent cortical areas directly, comparable to intraoperative direct cortical stimulation (DCS). The aim of this study was to evaluate the advantage of nTMS in comparison with functional magnetic resonance imaging (fMRI) in the clinical setting. Special focus was placed on accuracy of motor cortex localization in patients with rolandic lesions. Thirty consecutive patients were enrolled in the study. All patients received an fMRI and nTMS examination preoperatively. Feasibility of the technique and spatial resolution of upper and lower extremity cortical mapping were compared with fMRI. Consistency of preoperative mapping with intraoperative DCS was assessed via the neuronavigation system. nTMS was feasible in all 30 patients. fMRI was impossible in 7 out of 30 patients with special clinical conditions, pediatric patients, central vascular lesions, or compliance issues. The mean accuracy to localize motor cortex of nTMS was higher than in fMRI. In the subgroup of intrinsic tumors, nTMS produced statistically significant higher accuracy scores of the lower extremity localization than fMRI. fMRI failed to localize hand or leg areas in 6 out of 23 cases. Using nTMS, a preoperative localization of the central sulcus was possible in all patients. Verification of nTMS motor cortex localization with DCS was achieved in all cases. The fMRI localization of the hand area proved to be postcentral in one case. nTMS has fewer restrictions for preoperative functional mapping than fMRI and requires only a limited level of compliance. nTMS scores higher on the accuracy scale than fMRI. nTMS represents a highly valuable supplement for the preoperative functional planning in the clinical routine.
Publication: Neurosurg Rev. 2013 Jan;36(1):65-75; discussion 75-6. doi: 10.1007/s10143-012-0413-2. Epub 2012 Aug 11. http://www.ncbi.nlm.nih.gov/pubmed/22886323
Introduction: Direct cortical stimulation (DCS) is the gold-standard technique for motor mapping during craniotomy. However, preoperative noninvasive motor mapping is becoming increasingly accurate. Two such noninvasive modalities are navigated transcranial magnetic stimulation (TMS) and magnetoencephalography (MEG) imaging. While MEG imaging has already been extensively validated as an accurate modality of noninvasive motor mapping, TMS is less well studied. In this study, the authors compared the accuracy of TMS to both DCS and MEG imaging.
Methods: Patients with tumors in proximity to primary motor cortex underwent preoperative TMS and MEG imaging for motor mapping. The patients subsequently underwent motor mapping via intraoperative DCS. The loci of maximal response were recorded from each modality and compared. Motor strength was assessed at 3 months postoperatively.
Results: Transcranial magnetic stimulation and MEG imaging were performed on 24 patients. Intraoperative DCS yielded 8 positive motor sites in 5 patients. The median distance ± SEM between TMS and DCS motor sites was 2.13 ± 0.29 mm, and between TMS and MEG imaging motor sites was 4.71 ± 1.08 mm. In no patients did DCS motor mapping reveal a motor site that was unrecognized by TMS. Three of 24 patients developed new, early neurological deficit in the form of upper-extremity paresis. At the 3-month follow-up evaluation, 2 of these patients were significantly improved, experiencing difficulty only with fine motor tasks; the remaining patient had improvement to 4/5 strength. There were no deaths over the course of the study.
Conclusions: Maps of the motor system generated with TMS correlate well with those generated by both MEG imaging and DCS. Negative TMS mapping also correlates with negative DCS mapping. Navigated TMS is an accurate modality for noninvasively generating preoperative motor maps.
Publication: J Neurosurg. 2012 Aug;117(2):354-62. doi: 10.3171/2012.5.JNS112124. Epub 2012 Jun 15. http://www.ncbi.nlm.nih.gov/pubmed/22702484
Introduction: Navigated transcranial magnetic stimulation (nTMS) is a newly evolving technique. Despite its supposed purpose (for example, preoperative central region mapping), little is known about its accuracy compared with established modalities like direct cortical stimulation (DCS) and functional MR (fMR) imaging. Against this background, the authors performed the current study to compare the accuracy of nTMS with DCS and fMR imaging.
Methods: Fourteen patients with tumors in or close to the precentral gyrus were examined using nTMS for motor cortex mapping, as were 12 patients with lesions in the subcortical white matter motor tract. Moreover, preoperative fMR imaging and intraoperative mapping of the motor cortex were performed via DCS, and the outlining of the motor cortex was compared.
Results: In the 14 cases of lesions affecting the precentral gyrus, the primary motor cortex as outlined by nTMS correlated well with that delineated by intraoperative DCS mapping, with a deviation of 4.4 ± 3.4 mm between the two methods. In comparing nTMS with fMR imaging, the deviation between the two methods was much larger: 9.8 ± 8.5 mm for the upper extremity and 14.7 ± 12.4 mm for the lower extremity. In 13 of 14 cases, the surgeon admitted easier identification of the central region because of nTMS. The procedure had a subjectively positive influence on the operative results in 5 cases and was responsible for a changed resection strategy in 2 cases. One of 26 patients experienced nTMS as unpleasant; none found it painful.
Conclusions: Navigated TMS correlates well with DCS as a gold standard despite factors that are supposed to contribute to the inaccuracy of nTMS. Moreover, surgeons have found nTMS to be an additional and helpful modality during the resection of tumors affecting eloquent motor areas, as well as during preoperative planning.
Publication: Neurosurg. 2012 May;116(5):994-1001. doi: 10.3171/2011.12.JNS111524. Epub 2012 Feb 3. http://www.ncbi.nlm.nih.gov/pubmed/22304452http://thejns.org/doi/full/10.3171/2011.12.JNS111524
Introduction: Brain tumor surgery near the motor cortex requires careful planning to achieve the optimal balance between completeness of tumor resection and preservation of motor function. Navigated transcranial magnetic stimulation (nTMS) can be used to map functionally essential motor areas preoperatively.
Objective: To evaluate how much influence, benefit, and impact nTMS has on the surgical planning for tumors near the motor cortex.
Methods: This study reviewed the records of 73 patients with brain tumors in or near the motor cortex, mapped preoperatively with nTMS. The surgical team prospectively classified how much influence the nTMS results had on the surgical planning. Stepwise regression analysis was used to explore which factors predict the amount of influence, benefit, and impact nTMS has on the surgical planning.
Results: The influence of nTMS on the surgical planning was as follows: it confirmed the expected anatomy in 22% of patients, added knowledge that was not used in 23%, added awareness of high-risk areas in 27%, modified the approach in 16%, changed the planned extent of resection in 8%, and changed the surgical indication in 3%.
Conclusion: nTMS had an objective benefit on the surgical planning in one fourth of the patients and a subjective benefit in an additional half of the patients. It had an impact on the surgery itself in just more than half of the patients. By mapping the spatial relationship between the tumor and functional motor cortex, nTMS improves surgical planning for tumors in or near the motor cortex.
Publication: Neurosurgery. 2012 May;70(5):1248-56; discussion 1256-7. doi: 10.1227/NEU.0b013e318243881e. http://www.ncbi.nlm.nih.gov/pubmed/22127045
The Nexstim NBS System is indicated for noninvasive mapping of the primary motor cortex of the brain to its cortical gyrus. The NBS System provides information that may be used in the assessment of the primary motor cortex for pre-procedural planning.
Nexstim NexSpeech®, when used together with the NBS System, is indicated for noninvasive localization of cortical areas that do not contain essential speech function. NexSpeech® provides information that may be used in pre-surgical planning in patients undergoing brain surgery. Intraoperatively, the localization information provided by NexSpeech® is intended to be verified by direct cortical stimulation.
The Nexstim NBS System and NBS System with NexSpeech® are not intended to be used during a surgical procedure. The NBS System and NBS System with NexSpeech are intended to be used by trained clinical professionals.
1 Preoperative multimodal motor mapping: a comparison of magnetoencephalography imaging,navigated transcranial magnetic stimulation, and direct cortical stimulation By: Phiroz E. Tarapore, M.D., Mitchel S. Berger, M.D., et. al Journal of Neurosurgery. 2012 Aug;117(2):354-62. doi: 10.3171/2012.5.JNS112124
2 Preoperative motor mapping by navigated transcranial magnetic brain stimulation improves outcome for motor eloquent lesions By: Krieg SM, Ringel F, el. al Neuro-Oncology. 2014 Feb 9.
3 Navigated transcranial magnetic stimulation improves the treatment outcome in patients with brain tumors in motor eloquent locations By: Frey D, P Vajkoczy, T Picht, et. al Neuro-Oncology. 2014 Jun 12. pii: nou110.