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.
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.
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.
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.
Abbreviations used in this paper:AED = antiepilepsy drug; APB = abductor pollicis brevis; BOLD = blood oxygen level–dependent; CMAP = compound muscle action potential; DCS = direct cortical stimulation; DICOM = Digital Imaging and Communications in Medicine; EMG = electromyography; fMR = functional magnetic resonance; MEP = motor evoked potential; nTMS = navigated transcranial magnetic stimulation; rMT = resting motor threshold; SENSE = sensitivity encoding.
Address correspondence to: Florian Ringel, M.D., Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, 81675 Munich, Germany. email: Florian.Ringel@lrz.tum.de.
Please include this information when citing this paper: published online February 3, 2012; DOI: 10.3171/2011.12.JNS111524.
AhdabRAyacheSSBrugièresPGoujonCLefaucheurJP: Comparison of “standard” and “navigated” procedures of TMS coil positioning over motor, premotor and prefrontal targets in patients with chronic pain and depression. Neurophysiol Clin40:27–362010
Brasil-NetoJPCohenLGPanizzaMNilssonJRothBJHallettM: Optimal focal transcranial magnetic activation of the human motor cortex: effects of coil orientation, shape of the induced current pulse, and stimulus intensity. J Clin Neurophysiol9:132–1361992
ForsterMTHattingenESenftCGasserTSeifertVSzelényiA: Navigated transcranial magnetic stimulation and functional magnetic resonance imaging: advanced adjuncts in preoperative planning for central region tumors. Neurosurgery68:1317–13252011
KantelhardtSRFadiniTFinkeMKallenbergKSiemerkusJBockermannV: Robot-assisted image-guided transcranial magnetic stimulation for somatotopic mapping of the motor cortex: a clinical pilot study. Acta Neurochir (Wien)152:333–3432010
KringsTBuchbinderBRButlerWEChiappaKHJiangHJCosgroveGR: Functional magnetic resonance imaging and transcranial magnetic stimulation: complementary approaches in the evaluation of cortical motor function. Neurology48:1406–14161997
KrishnanRRaabeAHattingenESzelényiAYahyaHHermannE: Functional magnetic resonance imaging-integrated neuronavigation: correlation between lesion-to-motor cortex distance and outcome. Neurosurgery55:904–9152004
LehéricySDuffauHCornuPCapelleLPidouxBCarpentierA: Correspondence between functional magnetic resonance imaging somatotopy and individual brain anatomy of the central region: comparison with intraoperative stimulation in patients with brain tumors. J Neurosurg92:589–5982000
LevyWJAmassianVESchmidUDJungreisC: Mapping of motor cortex gyral sites non-invasively by transcranial magnetic stimulation in normal subjects and patients. Electroencephalogr Clin Neurophysiol Suppl43:51–751991
PichtTSchmidtSBrandtSFreyDHannulaHNeuvonenT: Preoperative functional mapping for rolandic brain tumor surgery: comparison of navigated transcranial magnetic stimulation to direct cortical stimulation. Neurosurgery69:581–5882011
PlewniaCReimoldMNajibAReischlGPlontkeSKGerloffC: Moderate therapeutic efficacy of positron emission tomography-navigated repetitive transcranial magnetic stimulation for chronic tinnitus: a randomised, controlled pilot study. J Neurol Neurosurg Psychiatry78:152–1562007
SuessOSuessSMularskiSKühnBPichtTSchönherrS: [Evaluation of a DC pulsed magnetic tracking system in neurosurgical navigation: technique, accuracies, and influencing factors.]. Biomed Tech (Berl)52:223–2332007. (Ger)
VaaltoSSäisänenLKönönenMJulkunenPHukkanenTMäättäS: Corticospinal output and cortical excitation-inhibition balance in distal hand muscle representations in nonprimary motor area. Hum Brain Mapp32:1692–17032011