Navigated Transcranial Magnetic Stimulation
DESCRIPTION
Navigated transcranial magnetic stimulation (nTMS) is proposed as a noninvasive imaging method for individuals with brain lesions to aid in the localization of eloquent areas of the brain to reduce damage to verbal and motor functions during surgery. Transcranial magnetic pulses are delivered to the individual as a navigation system calculates the strength, location, and direction of the stimulating magnetic field. The locations of these pulses are registered to a magnetic resonance image of the individual’s brain. Surface electromyography (EMG) electrodes are attached to the various limb muscles of the individual. Moving the magnetic stimulation source to various parts of the brain purportedly causes the EMG electrodes to respond, indicating the part of the cortex involved with muscle movements.
Surgical management of brain tumors necessitates mapping to preserve brain tissue and essential brain function. Mapping is most accurately achieved with direct cortical stimulation (DCS), which is performed intraoperatively.
POLICY
Navigated transcranial magnetic stimulation (nTMS) for all purposes including, but not limited to, preoperative evaluation of individuals being considered for brain surgery is considered investigational.
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ADDITIONAL INFORMATION
Limited studies of nTMS evaluating language areas have shown high false-positive rates that may be insufficient for clinical use. The evidence is insufficient to determine the effects of the technology on health outcomes.
SOURCES
BlueCross BlueShield Association. Evidence Positioning System. (7:2023). Navigated transcranial magnetic stimulation (2.01.90). Retrieved August 28, 2023 from http://www.evidencepositioningsystem.com/. (24 articles and/or guidelines reviewed)
Frey, D., Schilt, S., Strack, V., Zdunczyk, A., Rosler, J., Niraula, B., et al. (2014). Navigated transcranial magnetic stimulation improves the treatment outcome in patients with brain tumors in motor eloquent locations. Neuro-Oncology, 16 (10), 1365-1372. (Level 3 evidence)
Jeltema, H., Ohlerth, A., de Wit, A., Wagemakers, M., Rofes, A., Bastiaanse, R., & Drost, G. (2021). Comparing navigated transcranial magnetic stimulation mapping and "gold standard" direct cortical stimulation mapping in neurosurgery: a systematic review. Neurosurgical Review, 44 (4), 1903–1920. (Level 1 evidence)
Krieg, S. M., Sollmann, N., Hauck, T., Ille, S., Meyer, B., & Ringel, F. (2014). Repeated mapping of cortical language sites by preoperative navigated transcranial magnetic stimulation compared to repeated intraoperative DCS mapping in awake craniotomy. BMC Neuroscience, 15 (1), 20. (Level 3 evidence)
Sollmann, N., Hauck, T., Hapfelmeier, A., Meyer, B., Ringel, F., & Krieg, S. (2013). Intra- and interobserver variability of language mapping by navigated transcranial magnetic brain stimulation. BMC Neuroscience, 14, 150. (Level 3 evidence)
Takahashi, S., Vajkocy, P., & Picht, T. (2013). Navigated transcranial magnetic stimulation for mapping the motor cortex in patients with rolandic brain tumors. Neurosurgical Focus, 34 (4), 1-7. (Level 2 evidence)
U. S. Food and Drug Administration. (2011, September). Center for Devices and Radiological Health. 510(k) Premarket Notification Database. K112881. Retrieved May 16, 2016 from http://www.accessdata.fda.gov.
ORIGINAL EFFECTIVE DATE: 8/13/2005
MOST RECENT REVIEW DATE: 10/12/2023
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