Millimeter by Millimeter Towards a Better Prognosis

A method known as navigated transcranial magnetic stimulation (nTMS) has been gaining importance in neurosurgery for some time now. Among other applications, it is used to map brain tumors before an operation and to test whether important regions of the brain, for example motor and language areas, are affected. Doctors at the Technische Universität München (TUM) have now shown that preoperative nTMS analysis of motor areas improves the prognosis of patients with malignant brain tumors.

With the help of nTMS, it is possible to identify what areas of the brain control motor or language function to an accuracy of four millimeters. "That's particularly important, as it enables the removal of tumors from patients without affecting functional areas while at the same time removing as much of the malignant tissue as possible," explains Dr. Sandro Krieg, working group leader at the Department of Neurosurgery of TUM University Hospital Klinikum rechts der Isar and head of the study. Mapping must be performed separately for each patient, as tumors can displace important brain areas from their original sites.

Map for important motor areas
To determine motor areas with the nTMS technique, the physician scans points at defined positions on the patient's head using a coil. The coil induces brief painless electrical pulses in the brain, which stimulate brain neurons at those positions. If the pulses at a given position point activate neurons that trigger muscle movements, the scientists are able to measure the muscle activities with the help of electrodes fastened to the patient's arms and legs. That position is then regarded as an essential location for motor activity.

Up to 150 individual position points per patient can be analyzed and mapped. "In this way, we can draw up a map of important motor areas and nerve pathways in the vicinity of the tumor. During the operation, this data is a good guide as to where we can and cannot cut," explains Krieg. The method has been used at Klinikum rechts der Isar since 2010.

nTMS analysis improves prognosis
In their recent study, Sandro Krieg and his team scanned and mapped motor areas in patients with high-grade gliomas (HGG), which are usually associated with a poor prognosis. They compared two groups: 70 subjects who underwent preoperative nTMS analysis and 70 patients who underwent tumor surgery before nTMS became a standard procedure in the hospital.

The results of the study show the advantage of nTMS mapping for patients compared to the control group: smaller openings in the skull had to be made in patients who underwent nTMS tumor analysis, and residual tumor tissue was left behind less frequently. In addition, their average hospitalization period was two days shorter. Because the general state of health of the nTMS-treated patients was also better, an increased number of them were subsequently able to receive radiotherapy. Above all, those patients survived several months longer than the control group.

"Of course, we need to confirm the findings in larger patient groups, but one important thing is clear: preoperative tumor mapping positively influences many aspects of the procedure," Krieg says about the results, adding: "Some tumors that are otherwise thought to be inoperable can be removed by this method."

Refining protocols for nTMS
The scientists now aim to improve standard protocols for nTMS and, for example, the mapping of language areas. In a recent study, they showed that an object-naming test is the best method for analyzing language centers. "Language areas can already be mapped with nTMS, but they're much more complex than motor areas. We want to create higher standards in order to help patients with tumors in these regions as effectively as possible," the scientist says.

S. M. Krieg, N. Sollman, T. Obermüller, J. Sabih, L. Bulubas, C. Negwer, T. Moser, D. Droese, T. Boeckh-Behrens, F. Ringel, B. Meyer, Changing the clinical course of glioma patients by preoperative motor mapping with navigated transcranial magnetic brain stimulation, BMC Cancer, April 2015. DOI: 10.1186/s12885-015-1258-1

T. Hauck, N. Tanigawa, M. Probst, A. Wohlschlaeger, S. Ille, N. Sollmann, S. Maurer, C. Zimmer, F. Ringel, B. Meyer, S. M. Krieg, Task Type Affects Location of Language-Positive Cortical Regions by Repetitive Navigated Transcranial Magnetic Stimulation Mapping, PLOS ONE, April 2015. DOI: 10.1371/journal.pone.0125298

Most Popular Now

Researchers Find Telemedicine may Help R…

Low-value care - medical tests and procedures that provide little to no benefit to patients - contributes to excess medical spending and both direct and cascading harms to patients. A...

AI Revolutionizes Glaucoma Care

Imagine walking into a supermarket, train station, or shopping mall and having your eyes screened for glaucoma within seconds - no appointment needed. With the AI-based Glaucoma Screening (AI-GS) network...

AI may Help Clinicians Personalize Treat…

Individuals with generalized anxiety disorder (GAD), a condition characterized by daily excessive worry lasting at least six months, have a high relapse rate even after receiving treatment. Artificial intelligence (AI)...

Accelerating NHS Digital Maturity: Paper…

Digitised clinical noting at South Tees Hospitals NHS Foundation Trust is creating efficiencies for busy doctors and nurses. The trust’s CCIO Dr Andrew Adair, deputy CCIO Dr John Greenaway, and...

Mobile App Tracking Blood Pressure Helps…

The AHOMKA platform, an innovative mobile app for patient-to-provider communication that developed through a collaboration between the School of Engineering and leading medical institutions in Ghana, has yielded positive results...

AI can Open Up Beds in the ICU

At the height of the COVID-19 pandemic, hospitals frequently ran short of beds in intensive care units. But even earlier, ICUs faced challenges in keeping beds available. With an aging...

Can AI Help Detect Cognitive Impairment?

Mild cognitive impairment (MCI) can be an early indicator of Alzheimer's disease or dementia, so identifying those with cognitive issues early could lead to interventions and better outcomes. But diagnosing...

Customized Smartphone App Shows Promise …

A growing body of research indicates that older adults in assisted living facilities can delay or even prevent cognitive decline through interventions that combine multiple activities, such as improving diet...

New Study Shows Promise for Gamified mHe…

A new study published in Multiple Sclerosis and Related Disorders highlights the potential of More Stamina, a gamified mobile health (mHealth) app designed to help people with Multiple Sclerosis (MS)...

AI Model Predicting Two-Year Risk of Com…

AFib (short for atrial fibrillation), a common heart rhythm disorder in adults, can have disastrous consequences including life-threatening blood clots and stroke if left undetected or untreated. A new study...

Patients' Affinity for AI Messages …

In a Duke Health-led survey, patients who were shown messages written either by artificial intelligence (AI) or human clinicians indicated a preference for responses drafted by AI over a human...

New Research Explores How AI can Build T…

In today’s economy, many workers have transitioned from manual labor toward knowledge work, a move driven primarily by technological advances, and workers in this domain face challenges around managing non-routine...