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Zhang H, Zhang W, Ohlerth A, Schwendner M, Schröder A, Meyer B, Krieg SM, Ille S. Motor mapping of the hand muscles using peripheral innervation-based navigated transcranial magnetic stimulation to identify functional reorganization of primary motor regions in malignant tumors. Hum Brain Mapp 2024; 45:e26642. [PMID: 38433701 PMCID: PMC10910269 DOI: 10.1002/hbm.26642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 02/16/2024] [Accepted: 02/18/2024] [Indexed: 03/05/2024] Open
Abstract
Tumor-related motor reorganization remains unclear. Navigated transcranial magnetic stimulation (nTMS) can investigate plasticity non-invasively. nTMS-induced motor-evoked potentials (MEPs) of different muscles are commonly used to measure the center of gravity (CoG), the location with the highest density of corticospinal neurons in the precentral gyrus. We hypothesized that a peripheral innervation-based MEP analysis could outline the tumor-induced motor reorganization with a higher clinical and oncological relevance. Then, 21 patients harboring tumors inside the left corticospinal tract (CST) or precentral gyrus were enrolled in group one (G1), and 24 patients with tumors outside the left CST or precentral gyrus were enrolled in Group 2 (G2). Median- and ulnar-nerve-based MEP analysis combined with diffusion tensor imaging fiber tracking was used to explore motor function distribution. There was no significant difference in CoGs or size of motor regions and underlying tracts between G1 and G2. However, G1 involved a sparser distribution of motor regions and more motor-positive sites in the supramarginal gyrus-tumors inside motor areas induced motor reorganization. We propose an "anchor-and-ship theory" hypothesis for this process of motor reorganization: motor CoGs are stably located in the cortical projection area of the CST, like a seated anchor, as the core area for motor output. Primary motor regions can relocate to nearby gyri via synaptic plasticity and association fibers, like a ship moving around its anchor. This principle can anticipate functional reorganization and be used as a neuro-oncological tool for local therapy, such as radiotherapy or surgery.
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Affiliation(s)
- Haosu Zhang
- Department of NeurosurgeryTechnical University of Munich, School of MedicineMunichGermany
- Department of NeurosurgeryHeidelberg University HospitalHeidelbergGermany
| | - Wei Zhang
- Department of NeurosurgeryTechnical University of Munich, School of MedicineMunichGermany
| | - Ann‐Katrin Ohlerth
- Department of NeurosurgeryTechnical University of Munich, School of MedicineMunichGermany
- Center for Language and Cognition GroningenUniversity of GroningenGroningenNetherlands
| | - Maximilian Schwendner
- Department of NeurosurgeryTechnical University of Munich, School of MedicineMunichGermany
- Department of NeurosurgeryHeidelberg University HospitalHeidelbergGermany
| | - Axel Schröder
- Department of NeurosurgeryTechnical University of Munich, School of MedicineMunichGermany
| | - Bernhard Meyer
- Department of NeurosurgeryTechnical University of Munich, School of MedicineMunichGermany
| | - Sandro M. Krieg
- Department of NeurosurgeryTechnical University of Munich, School of MedicineMunichGermany
- Department of NeurosurgeryHeidelberg University HospitalHeidelbergGermany
- TUM‐Neuroimaging CenterTechnical University of Munich, School of MedicineMunichGermany
| | - Sebastian Ille
- Department of NeurosurgeryTechnical University of Munich, School of MedicineMunichGermany
- Department of NeurosurgeryHeidelberg University HospitalHeidelbergGermany
- TUM‐Neuroimaging CenterTechnical University of Munich, School of MedicineMunichGermany
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Demjan M, Säisänen L, Reijonen J, Rissanen S, Määttä S, Julkunen P. Near-threshold recruitment characteristics of motor evoked potentials in transcranial magnetic stimulation. Brain Res 2023; 1805:148284. [PMID: 36796474 DOI: 10.1016/j.brainres.2023.148284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 01/13/2023] [Accepted: 02/12/2023] [Indexed: 02/16/2023]
Abstract
Transcranial magnetic stimulation (TMS) can induce motor evoked potentials (MEPs). In TMS applications, near-threshold stimulation intensities (SIs) are often used for characterizing corticospinal excitability using MEPs. We aimed to characterize the individual near-threshold recruitment of MEPs and to test the assumptions related to selection of the suprathreshold SI. We utilized MEP data from a right-hand muscle induced at variable SIs. The single-pulse TMS (spTMS) data from previous studies (27 healthy volunteers), as well as data from new measurements (10 healthy volunteers) that included also MEPs modulated by paired-pulse TMS (ppTMS), were included. The probability of MEP (pMEP) was represented with individually fitted cumulative distribution function (CDF) with two parameters: resting motor threshold (rMT) and spread relative to rMT. MEPs were recorded with 110% and 120% of rMT as well as with Mills-Nithi upper threshold (UT). The individual near-threshold characteristics varied with CDF parameters: the rMT and the relative spread (median: 0.052). The rMT was lower with ppTMS than with spTMS (p < 0.001), while the relative spread remained similar (p = 0.812). At suprathreshold SIs, the probability of MEP was similar between UT and 110% of rMT (pMEP > 0.88), and higher for 120% of rMT (pMEP > 0.98). The individual near-threshold characteristics determine how probably MEPs are produced at common suprathreshold SIs. At the population level, the used SIs UT and 110% of rMT produced MEPs at similar probability. The individual variability in the relative spread parameter was large; therefore, the method of determining the proper suprathreshold SI for TMS applications is of crucial importance.
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Affiliation(s)
- Michal Demjan
- Department of Clinical Neurophysiology, Kuopio University Hospital, POB 100, 70200 KYS Kuopio, Finland; Department of Technical Physics, University of Eastern Finland, POB 1627, 70210 Kuopio, Finland; Bittium Biosignals Oy, Pioneerinkatu 6, 70800 Kuopio, Finland
| | - Laura Säisänen
- Department of Technical Physics, University of Eastern Finland, POB 1627, 70210 Kuopio, Finland
| | - Jusa Reijonen
- Department of Clinical Neurophysiology, Kuopio University Hospital, POB 100, 70200 KYS Kuopio, Finland; Department of Technical Physics, University of Eastern Finland, POB 1627, 70210 Kuopio, Finland
| | - Saara Rissanen
- Department of Technical Physics, University of Eastern Finland, POB 1627, 70210 Kuopio, Finland
| | - Sara Määttä
- Department of Clinical Neurophysiology, Kuopio University Hospital, POB 100, 70200 KYS Kuopio, Finland
| | - Petro Julkunen
- Department of Clinical Neurophysiology, Kuopio University Hospital, POB 100, 70200 KYS Kuopio, Finland; Department of Technical Physics, University of Eastern Finland, POB 1627, 70210 Kuopio, Finland.
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Assessing the feasibility of mapping the tibialis anterior muscle with navigated transcranial magnetic stimulation in neuro-oncologic patients. Sci Rep 2022; 12:18719. [PMID: 36333400 PMCID: PMC9636142 DOI: 10.1038/s41598-022-23444-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
Mapping the lower extremity with navigated transcranial magnetic stimulation (nTMS) still remains challenging for the investigator. Clinical factors influencing leg mapping with nTMS have not been fully investigated yet. The aim of the study was to identify factors which influence the possibility of eliciting motor evoked potentials (MEPs) from the tibialis anterior muscle (TA). Patient records, imaging, nTMS examinations and tractography were retrospectively evaluated. 48 nTMS examinations were performed in 46 brain tumor patients. Reproducible MEPs were recorded in 20 patients (41.67%). Younger age (p = 0.044) and absence of perifocal edema (p = 0.035, Cramer's V = 0.34, OR = 0.22, 95% CI = 0.06-0.81) facilitated mapping the TA muscle. Leg motor deficit (p = 0.49, Cramer's V = 0.12, OR = 0.53, 95%CI = 0.12-2.36), tumor entity (p = 0.36, Cramer's V = 0.22), tumor location (p = 0.52, Cramer's V = 0.26) and stimulation intensity (p = 0.158) were no significant factors. The distance between the tumor and the pyramidal tract was higher (p = 0.005) in patients with successful mapping of the TA. The possibility to stimulate the leg motor area was associated with no postoperative aggravation of motor deficits in general (p = 0.005, Cramer's V = 0.45, OR = 0.63, 95%CI = 0.46-0.85) but could not serve as a specific predictor of postoperative lower extremity function. In conclusion, successful mapping of the TA muscle for neurosurgical planning is influenced by young patient age, absence of edema and greater distance to the CST, whereas tumor entity and stimulation intensity were non-significant.
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Duport A, Pelletier R, Martel M, Léonard G. The influence of kinesiophobia and pain catastrophizing on pain-induced corticomotor modulation in healthy participants: A cross sectional study. Neurophysiol Clin 2022; 52:375-383. [DOI: 10.1016/j.neucli.2022.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 08/11/2022] [Accepted: 08/14/2022] [Indexed: 11/06/2022] Open
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Giuffre A, Zewdie E, Wrightson JG, Cole L, Carlson HL, Kuo HC, Babwani A, Kirton A. Effects of Transcranial Direct Current Stimulation and High-Definition Transcranial Direct Current Stimulation Enhanced Motor Learning on Robotic Transcranial Magnetic Stimulation Motor Maps in Children. Front Hum Neurosci 2021; 15:747840. [PMID: 34690726 PMCID: PMC8526891 DOI: 10.3389/fnhum.2021.747840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/16/2021] [Indexed: 11/13/2022] Open
Abstract
Introduction: Conventional transcranial direct current stimulation (tDCS) and high-definition tDCS (HD-tDCS) may improve motor learning in children. Mechanisms are not understood. Neuronavigated robotic transcranial magnetic stimulation (TMS) can produce individualised maps of primary motor cortex (M1) topography. We aimed to determine the effects of tDCS- and HD-tDCS-enhanced motor learning on motor maps. Methods: Typically developing children aged 12-18 years were randomised to right M1 anodal tDCS, HD-tDCS, or Sham during training of their left-hand on the Purdue Pegboard Task (PPT) over 5 days. Bilateral motor mapping was performed at baseline (pre), day 5 (post), and 6-weeks retention time (RT). Primary muscle was the first dorsal interosseous (FDI) with secondary muscles of abductor pollicis brevis (APB) and adductor digiti minimi (ADM). Primary mapping outcomes were volume (mm2/mV) and area (mm2). Secondary outcomes were centre of gravity (COG, mm) and hotspot magnitude (mV). Linear mixed-effects modelling was employed to investigate effects of time and stimulation type (tDCS, HD-tDCS, Sham) on motor map characteristics. Results: Twenty-four right-handed participants (median age 15.5 years, 52% female) completed the study with no serious adverse events or dropouts. Quality maps could not be obtained in two participants. No effect of time or group were observed on map area or volume. LFDI COG (mm) differed in the medial-lateral plane (x-axis) between tDCS and Sham (p = 0.038) from pre-to-post mapping sessions. Shifts in map COG were also observed for secondary left-hand muscles. Map metrics did not correlate with behavioural changes. Conclusion: Robotic TMS mapping can safely assess motor cortex neurophysiology in children undergoing motor learning and neuromodulation interventions. Large effects on map area and volume were not observed while changes in COG may occur. Larger controlled studies are required to understand the role of motor maps in interventional neuroplasticity in children.
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Affiliation(s)
- Adrianna Giuffre
- Calgary Pediatric Stroke Program, Alberta Children's Hospital, Calgary, AB, Canada.,Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Ephrem Zewdie
- Calgary Pediatric Stroke Program, Alberta Children's Hospital, Calgary, AB, Canada.,Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - James G Wrightson
- Calgary Pediatric Stroke Program, Alberta Children's Hospital, Calgary, AB, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Lauran Cole
- Calgary Pediatric Stroke Program, Alberta Children's Hospital, Calgary, AB, Canada
| | - Helen L Carlson
- Calgary Pediatric Stroke Program, Alberta Children's Hospital, Calgary, AB, Canada.,Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Hsing-Ching Kuo
- Department of Physical Medicine & Rehabilitation, University of California, Davis, Sacramento, CA, United States
| | - Ali Babwani
- Calgary Pediatric Stroke Program, Alberta Children's Hospital, Calgary, AB, Canada
| | - Adam Kirton
- Calgary Pediatric Stroke Program, Alberta Children's Hospital, Calgary, AB, Canada.,Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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Sollmann N, Krieg SM, Säisänen L, Julkunen P. Mapping of Motor Function with Neuronavigated Transcranial Magnetic Stimulation: A Review on Clinical Application in Brain Tumors and Methods for Ensuring Feasible Accuracy. Brain Sci 2021; 11:brainsci11070897. [PMID: 34356131 PMCID: PMC8305823 DOI: 10.3390/brainsci11070897] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 06/29/2021] [Accepted: 07/02/2021] [Indexed: 12/15/2022] Open
Abstract
Navigated transcranial magnetic stimulation (nTMS) has developed into a reliable non-invasive clinical and scientific tool over the past decade. Specifically, it has undergone several validating clinical trials that demonstrated high agreement with intraoperative direct electrical stimulation (DES), which paved the way for increasing application for the purpose of motor mapping in patients harboring motor-eloquent intracranial neoplasms. Based on this clinical use case of the technique, in this article we review the evidence for the feasibility of motor mapping and derived models (risk stratification and prediction, nTMS-based fiber tracking, improvement of clinical outcome, and assessment of functional plasticity), and provide collected sets of evidence for the applicability of quantitative mapping with nTMS. In addition, we provide evidence-based demonstrations on factors that ensure methodological feasibility and accuracy of the motor mapping procedure. We demonstrate that selection of the stimulation intensity (SI) for nTMS and spatial density of stimuli are crucial factors for applying motor mapping accurately, while also demonstrating the effect on the motor maps. We conclude that while the application of nTMS motor mapping has been impressively spread over the past decade, there are still variations in the applied protocols and parameters, which could be optimized for the purpose of reliable quantitative mapping.
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Affiliation(s)
- Nico Sollmann
- Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Ismaninger Str. 22, 81675 Munich, Germany
- TUM-Neuroimaging Center, Klinikum rechts der Isar, Technical University of Munich, 81675 Munich, Germany;
- Department of Radiology and Biomedical Imaging, University of California San Francisco, 185 Berry Street, San Francisco, CA 94143, USA
- Correspondence:
| | - Sandro M. Krieg
- TUM-Neuroimaging Center, Klinikum rechts der Isar, Technical University of Munich, 81675 Munich, Germany;
- Department of Neurosurgery, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Ismaninger Str. 22, 81675 Munich, Germany
| | - Laura Säisänen
- Department of Clinical Neurophysiology, Kuopio University Hospital, 70029 Kuopio, Finland; (L.S.); (P.J.)
- Department of Applied Physics, University of Eastern Finland, 70211 Kuopio, Finland
| | - Petro Julkunen
- Department of Clinical Neurophysiology, Kuopio University Hospital, 70029 Kuopio, Finland; (L.S.); (P.J.)
- Department of Applied Physics, University of Eastern Finland, 70211 Kuopio, Finland
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Cavaleri R, Chipchase LS, Summers SJ, Chalmers J, Schabrun SM. The Relationship Between Corticomotor Reorganization and Acute Pain Severity: A Randomized, Controlled Study Using Rapid Transcranial Magnetic Stimulation Mapping. PAIN MEDICINE 2021; 22:1312-1323. [PMID: 33367763 DOI: 10.1093/pm/pnaa425] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Although acute pain has been shown to reduce corticomotor excitability, it remains unknown whether this response resolves over time or is related to symptom severity. Furthermore, acute pain research has relied upon data acquired from the cranial "hotspot," which do not provide valuable information regarding reorganization, such as changes to the distribution of a painful muscle's representation within M1. Using a novel, rapid transcranial magnetic stimulation (TMS) mapping method, this study aimed to 1) explore the temporal profile and variability of corticomotor reorganization in response to acute pain and 2) determine whether individual patterns of corticomotor reorganization are associated with differences in pain, sensitivity, and somatosensory organization. METHODS Corticomotor (TMS maps), pain processing (pain intensity, pressure pain thresholds), and somatosensory (two-point discrimination, two-point estimation) outcomes were taken at baseline, immediately after injection (hypertonic [n = 20] or isotonic saline [n = 20]), and at pain resolution. Follow-up measures were recorded every 15 minutes until 90 minutes after injection. RESULTS Corticomotor reorganization persisted at least 90 minutes after pain resolution. Corticomotor depression was associated with lower pain intensity than was corticomotor facilitation (r = 0.47 [P = 0.04]). These effects were not related to somatosensory reorganization or peripheral sensitization mechanisms. CONCLUSIONS Individual patterns of corticomotor reorganization during acute pain appear to be related to symptom severity, with early corticomotor depression possibly reflecting a protective response. These findings hold important implications for the management and potential prevention of pain chronicity. However, further research is required to determine whether these adaptations relate to long-term outcomes in clinical populations.
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Affiliation(s)
- Rocco Cavaleri
- Brain Stimulation and Rehabilitation (BrainStAR) Lab, School of Health Sciences, Western Sydney University, Sydney, New South Wales, Australia
| | - Lucy S Chipchase
- Brain Stimulation and Rehabilitation (BrainStAR) Lab, School of Health Sciences, Western Sydney University, Sydney, New South Wales, Australia.,College of Nursing and Health Sciences, Flinders University, Adelaide, South Australia, Australia
| | - Simon J Summers
- Brain Stimulation and Rehabilitation (BrainStAR) Lab, School of Health Sciences, Western Sydney University, Sydney, New South Wales, Australia.,Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, Australian Capital Territory, Australia
| | - Jane Chalmers
- Brain Stimulation and Rehabilitation (BrainStAR) Lab, School of Health Sciences, Western Sydney University, Sydney, New South Wales, Australia.,IIMPACT in Health, University of South Australia, Adelaide, South Australia, Australia
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Short-Interval Intracortical Facilitation Improves Efficacy in nTMS Motor Mapping of Lower Extremity Muscle Representations in Patients with Supra-Tentorial Brain Tumors. Cancers (Basel) 2020; 12:cancers12113233. [PMID: 33147827 PMCID: PMC7692031 DOI: 10.3390/cancers12113233] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 02/06/2023] Open
Abstract
Navigated transcranial magnetic stimulation (nTMS) is increasingly used for mapping of motor function prior to surgery in patients harboring motor-eloquent brain lesions. To date, single-pulse nTMS (sp-nTMS) has been predominantly used for this purpose, but novel paired-pulse nTMS (pp-nTMS) with biphasic pulse application has been made available recently. The purpose of this study was to systematically evaluate pp-nTMS with biphasic pulses in comparison to conventionally used sp-nTMS for preoperative motor mapping of lower extremity (lE) muscle representations. Thirty-nine patients (mean age: 56.3 ± 13.5 years, 69.2% males) harboring motor-eloquent brain lesions of different entity underwent motor mapping of lE muscle representations in lesion-affected hemispheres and nTMS-based tractography of the corticospinal tract (CST) using data from sp-nTMS and pp-nTMS with biphasic pulses, respectively. Compared to sp-nTMS, pp-nTMS enabled motor mapping with lower stimulation intensities (61.8 ± 13.8% versus 50.7 ± 11.6% of maximum stimulator output, p < 0.0001), and it provided reliable motor maps even in the most demanding cases where sp-nTMS failed (pp-nTMS was able to provide a motor map in five patients in whom sp-nTMS did not provide any motor-positive points, and pp-nTMS was the only modality to provide a motor map in one patient who also did not show motor-positive points during intraoperative stimulation). Fiber volumes of the tracked CST were slightly higher when motor maps of pp-nTMS were used, and CST tracking using pp-nTMS data was also possible in the five patients in whom sp-nTMS failed. In conclusion, application of pp-nTMS with biphasic pulses enables preoperative motor mapping of lE muscle representations even in the most challenging patients in whom the motor system is at high risk due to lesion location or resection.
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Sollmann N, Zhang H, Kelm A, Schröder A, Meyer B, Pitkänen M, Julkunen P, Krieg SM. Paired-pulse navigated TMS is more effective than single-pulse navigated TMS for mapping upper extremity muscles in brain tumor patients. Clin Neurophysiol 2020; 131:2887-2898. [PMID: 33166740 DOI: 10.1016/j.clinph.2020.09.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 08/10/2020] [Accepted: 09/09/2020] [Indexed: 01/16/2023]
Abstract
OBJECTIVE Single-pulse navigated transcranial magnetic stimulation (sp-nTMS) is used for presurgical motor mapping in patients with motor-eloquent lesions. However, recently introduced paired-pulse nTMS (pp-nTMS) with biphasic pulses could improve motor mapping. METHODS Thirty-four patients (mean age: 56.0 ± 12.7 years, 53.0% high-grade glioma) with motor-eloquent lesions underwent motor mapping of upper extremity representations and nTMS-based tractography of the corticospinal tract (CST) by both sp-nTMS and pp-nTMS with biphasic pulses for the tumor-affected hemisphere before resection. RESULTS In three patients (8.8%), conventional sp-nTMS did not provide motor-positive points, in contrast to pp-nTMS that was capable of generating motor maps in all patients. Good concordance between pp-nTMS and sp-nTMS in the spatial location of motor hotspots and center of gravity (CoG) as well as for CST tracking was observed, with pp-nTMS leading to similar motor map volumes (585.0 ± 667.8 vs. 586.8 ± 204.2 mm3, p = 0.9889) with considerably lower resting motor thresholds (35.0 ± 8.8 vs. 32.8 ± 7.6% of stimulator output, p = 0.0004). CONCLUSIONS Pp-nTMS with biphasic pulses may provide motor maps even in highly demanding cases with tumor-affected motor structures or edema, using lower stimulation intensity compared to sp-nTMS. SIGNIFICANCE Pp-nTMS with biphasic pulses could replace standardly used sp-nTMS for motor mapping and may be safer due to lower stimulation intensity.
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Affiliation(s)
- Nico Sollmann
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany; TUM-Neuroimaging Center, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
| | - Haosu Zhang
- Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany
| | - Anna Kelm
- Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
| | - Axel Schröder
- Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
| | - Bernhard Meyer
- Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
| | - Minna Pitkänen
- Department of Clinical Neurophysiology, Kuopio University Hospital, POB 100, 70029 KYS, Kuopio, Finland; A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
| | - Petro Julkunen
- Department of Clinical Neurophysiology, Kuopio University Hospital, POB 100, 70029 KYS, Kuopio, Finland; Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
| | - Sandro M Krieg
- TUM-Neuroimaging Center, Klinikum rechts der Isar, Technische Universität München, Munich, Germany; Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
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10
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Reijonen J, Pitkänen M, Kallioniemi E, Mohammadi A, Ilmoniemi RJ, Julkunen P. Spatial extent of cortical motor hotspot in navigated transcranial magnetic stimulation. J Neurosci Methods 2020; 346:108893. [PMID: 32791087 DOI: 10.1016/j.jneumeth.2020.108893] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 07/05/2020] [Accepted: 08/02/2020] [Indexed: 12/21/2022]
Abstract
BACKGROUND Motor mapping with navigated transcranial magnetic stimulation (nTMS) requires defining a "hotspot", a stimulation site consistently producing the highest-amplitude motor-evoked potentials (MEPs). The exact location of the hotspot is difficult to determine, and the spatial extent of high-amplitude MEPs usually remains undefined due to MEP variability and the spread of the TMS-induced electric field (E-field). Therefore, here we aim to define the hotspot as a sub-region of a motor map. NEW METHOD We analyzed MEP amplitude distributions in motor mappings of 30 healthy subjects in two orthogonal directions on the motor cortex. Based on the widths of these distributions, the hotspot extent was estimated as an elliptic area. In addition, E-field distributions induced by motor map edge stimulations were simulated for ten subjects, and the E-field attenuation was analyzed to obtain another estimate for hotspot extent. RESULTS The median MEP-based hotspot area was 13 mm2 (95% confidence interval (CI) = [10, 18] mm2). The mean E-field-based hotspot area was 26 mm2 (95% CI = [13, 38] mm2). COMPARISON WITH EXISTING METHODS In contrast to the conventional hotspot, the new definition considers its spatial extent, indicating the most easily excited area where subsequent nTMS stimuli should be targeted for maximal response. The E-field-based hotspot provides an estimate for the extent of cortical structures where the E-field is close to its maximum. CONCLUSIONS The nTMS hotspot should be considered as an area rather than a single qualitatively defined spot due to MEP variability and E-field spread.
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Affiliation(s)
- Jusa Reijonen
- Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
| | - Minna Pitkänen
- Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
| | - Elisa Kallioniemi
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States.
| | - Ali Mohammadi
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
| | - Risto J Ilmoniemi
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
| | - Petro Julkunen
- Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
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11
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Julkunen P. Mobile Application for Adaptive Threshold Hunting in Transcranial Magnetic Stimulation. IEEE Trans Neural Syst Rehabil Eng 2019; 27:1504-1510. [PMID: 31265403 DOI: 10.1109/tnsre.2019.2925904] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Application of transcranial magnetic stimulation (TMS) is expanding with many studies applying adaptive threshold hunting to determine a motor threshold (MT). In addition to being a measure of corticospinal excitability, the MT is used as a baseline stimulation intensity (SI) to which following investigative or modulatory SIs are referenced to. Currently available tools for determining MTs include system-integrated tools and third-party stand-alone software. System-integrated MT-tools are still rarely available and the stand-alone software usually demand a separate computer, and hence possess additional space-requirements. I introduce and validate a free Android-based mobile application ("ATH-tool") for adaptive threshold hunting of the MT. The objective is to allow for a simple and validated recording of MTs with sharing capabilities for logs. For comparison, I applied Motor Threshold Assessment Tool 2.0, to compare the MT-values determined with the new application, as it applies closely the same routine. Computational validation with known true threshold values confirmed that the new application captured the true MT at high precision (error ≤ 0.9%). Previously published data on motor evoked potentials (MEPs) were used to simulate realistic response occurrence by considering experimental data from 15 healthy subjects at different stimulation intensities. The MTs of the different methods agreed well (ICC ≥ 0.971, ). There was no significant difference between the MTs determined with the different methods ( p ≥ 0.151 ). The novel mobile application should make it easier for researchers and clinicians to determine MTs and log the results.
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