TMSmap – Software for Quantitative Analysis of TMS Mapping Results

Abstract

The use of the MRI-navigation system ensures accurate targeting of TMS. This, in turn, results in TMS motor mapping becoming a routinely used procedure in neuroscience and neurosurgery. However, currently, there is no standardized methodology for assessment of TMS motor-mapping results. Therefore, we developed TMSmap—free standalone graphical interface software for the quantitative analysis of the TMS motor mapping results (http://tmsmap.ru/). In addition to the estimation of standard parameters (such as the size of cortical muscle representation and the center of gravity location), it allows estimation of the volume of cortical representations, excitability profile of the cortical surface map, and the overlap between cortical representations. The input data for the software includes the coordinates of the coil position (or electric field maximum) and the corresponding response in each stimulation point. TMSmap has been developed for versatile assessment and comparison of TMS maps relating to different experimental interventions including, but not limited to longitudinal, pharmacological and clinical studies (e.g., stroke recovery). To illustrate the use of TMSmap we provide examples of the actual TMS motor-mapping analysis of two healthy subjects and one chronic stroke patient.

TMS cortical mapping of multiple muscles: absolute and relative test-retest reliability

“…MCRs were constructed and analyzed using TMSmapa freely available software for the quantitative assessment of TMS cortical mapping data, which we developed and described previously (Novikov, Nazarova, & Nikulin, 2018). We calculated commonly used size MCR parameters such as areas, volumes, mean MEP per MCR, and topography parameters such as hotspot and COG locations (the COG formula was the same as elsewhere, including the TMSmap software description (Novikov et al, 2018). We merged stimulation points located closer than 2 mm (see Figure 1) (Novikov et al, 2018) and used mean MEP amplitudes after merging for MCR construction.…”

“…We calculated commonly used size MCR parameters such as areas, volumes, mean MEP per MCR, and topography parameters such as hotspot and COG locations (the COG formula was the same as elsewhere, including the TMSmap software description (Novikov et al, 2018). We merged stimulation points located closer than 2 mm (see Figure 1) (Novikov et al, 2018) and used mean MEP amplitudes after merging for MCR construction. The threshold MEP amplitude for MCR construction was 50 µV for a merged point.…”

“…Most commonly, during TMS motor mapping one investigates motor evoked potentials (MEPs) using surface (Rossini et al, 2015) or needle EMG (Massé-Alarie, Bergin, Schneider, Schabrun, & Hodges, 2017). When MEPs from the stimulation of many cortical points are acquired, the resulting output is referred to as cortical muscle representation (MCR) (Bashir, Perez, Horvath, & Pascual-Leone, 2013;de Carvalho, Miranda, Luis, & Ducla-Soares, 1999), also known as TMS cortical motor map (Kraus & Gharabaghi, 2015;Novikov, Nazarova, & Nikulin, 2018). There are numerous studies showing that the MCR parameters such as excitability, size and topography reflect functionally relevant features of the motor cortex organization in healthy people (Beaulieu, Flamand, Massé-Alarie, & Schneider, 2017;Gentner & Classen, 2006;Nazarova, Novikov, Nikulin, & Ivanova, 2020;Tyč & Boyadjian, 2011) and in patients with motor pathology such as stroke (Lüdemann-Podubecká & Nowak, 2016;Yarossi et al, 2019), amyotrophic lateral sclerosis (Chervyakov et al, 2015;de Carvalho et al, 1999), dystonia (Schabrun, Stinear, Byblow, & Ridding, 2009) etc.…”

“…Furthermore, another limitation, considering TMS MCR reliability, is the lack of an agreement on which MCR parameters should actually be studied. Apart from the MCR parameters commonly used and recommended in the TMS clinical guidelines, such as areas, volumes, COGs and hotspots (Rossini et al, 2015) there is a range of more sophisticated parameters, such as MCR shape (Pitkänen et al, 2017), discrete peaks per MCR (Beaulieu, Flamand, et al, 2017;Cavaleri, Schabrun, & Chipchase, 2017;Schabrun, Hodges, Vicenzino, Jones, & Chipchase, 2015), MCR excitability profile (EP) (Novikov et al, 2018;Raffin et al, 2015) etc., but the validity of these parameters has not yet been fully established.…”

Optimization of the navigated TMS mapping algorithm for accurate detection of plasticity and abnormalities in cortical muscle representations

“…The area of a representation mapped using the grid-based method has been defined as the total area of the cells with at least one suprathreshold MEP out of three stimuli [22], at least five out of ten [23], six out of ten [21,24], or two out of six [25] suprathreshold MEPs. Several studies have studied the area in which an interpolated mean amplitude function exceeds some threshold, with varying interpolation methods and thresholds [17,36,37]. Recently, a more advanced minimum-norm estimation procedure has been proposed [38].…”