A Single Session of rTMS Enhances Small-Worldness in Writer’s Cramp: Evidence from Simultaneous EEG-fMRI Multi-Modal Brain Graph

Abstract

Background and Purpose: Repetitive transcranial magnetic stimulation (rTMS) induces widespread changes in brain connectivity. As the network topology differences induced by a single session of rTMS are less known we undertook this study to ascertain whether the network alterations had a small-world morphology using multi-modal graph theory analysis of simultaneous EEG-fMRI.Method: Simultaneous EEG-fMRI was acquired in duplicate before (R1) and after (R2) a single session of rTMS in 14 patients with Writer’s Cramp (WC). Whole brain neuronal and hemodynamic network connectivity were explored using the graph theory measures and clustering coefficient, path length and small-world index were calculated for EEG and resting state fMRI (rsfMRI). Multi-modal graph theory analysis was used to evaluate the correlation of EEG and fMRI clustering coefficients.Result: A single session of rTMS was found to increase the clustering coefficient and small-worldness significantly in both EEG and fMRI (p < 0.05). Multi-modal graph theory analysis revealed significant modulations in the fronto-parietal regions immediately after rTMS. The rsfMRI revealed additional modulations in several deep brain regions including cerebellum, insula and medial frontal lobe.Conclusion: Multi-modal graph theory analysis of simultaneous EEG-fMRI can supplement motor physiology methods in understanding the neurobiology of rTMS in vivo. Coinciding evidence from EEG and rsfMRI reports small-world morphology for the acute phase network hyper-connectivity indicating changes ensuing low-frequency rTMS is probably not “noise”.

Lasting Effects of Low-Frequency Repetitive Transcranial Magnetic Stimulation in Writer’s Cramp: A Case Report

“…Even though the study is a single-case report, our data suggest that low-frequency rTMS over the PMC is able to revert both the abnormal sensorimotor plasticity and the lack of topographical specificity of muscle activation that characterize W’sC pathophysiology, thus improving motor symptoms. The large effects of rTMS on sensorimotor plasticity and topographical specificity of muscle activation, we found may have occurred through a low-frequency induced reduction of an abnormally high excitatory output going from the PMC to the sensorimotor regions (through cortico-basal ganglia-cortical loops), as indicated by some studies employing TMS and EEG (Teulings, 1996; Siebner et al, 1999; Paus et al, 2001; Strafella et al, 2001; Houdayer et al, 2008; Borich et al, 2009; Kantak et al, 2012; Bharath et al, 2015, 2017; Haith et al, 2016; Longcamp et al, 2016; Antelmi et al, 2017). This is particularly relevant during handwriting in patients with focal dystonia.…”

“…Nonetheless, the clinical effects lasted no more than 10–14 days after the treatment completion (Gersner et al, 2011). Negative reports on the clinical effectiveness of low-frequency rTMS are also available (Bharath et al, 2015, 2017; Zhang et al, 2017). The design of such studies were single/double-blinded and sham-controlled.…”

“…Notably, the paradigms by Kimberley et al (2013, 2015) was delivered while the patients were engaged in a motor task not triggering dystonic symptoms or sensorimotor training or non-specific stretching/massage. These studies reported no effects in terms of global clinical score and handwriting performance (Zhang et al, 2017), no additional benefit from sensorimotor retraining, and no significant differences between real and sham rTMS (Bharath et al, 2015, 2017). Nonetheless, there were some neurophysiological changes to acknowledge, including a cerebral blood flow reduction in lateral and medial premotor areas, putamen and the thalamus (Zhang et al, 2017), an increased intracortical inhibition (CSP increase), and a reduced pen grip force (Bharath et al, 2015, 2017).…”

“…These studies reported no effects in terms of global clinical score and handwriting performance (Zhang et al, 2017), no additional benefit from sensorimotor retraining, and no significant differences between real and sham rTMS (Bharath et al, 2015, 2017). Nonetheless, there were some neurophysiological changes to acknowledge, including a cerebral blood flow reduction in lateral and medial premotor areas, putamen and the thalamus (Zhang et al, 2017), an increased intracortical inhibition (CSP increase), and a reduced pen grip force (Bharath et al, 2015, 2017). All the above-mentioned studies share the low frequency of stimulation, in keeping with the rationale of inhibiting the cortical motor areas contralateral to the affected side (Siebner et al, 1999, 2003; Murase et al, 2005).…”

Mathematics home-school partnerships in diverse contexts

“…For Tongan and Samoan participants, the two focus groups aligned with a Talanoa method (an inclusive, transparent, and participatory dialogue). Vaioleti (2006) argues that Talanoa allows people to share their true stories, which results in more authentic data than in other methods. The main difference of a Talanoa focus group compared to a traditional focus group is that the precise nature of questions is not decided in advance; instead, an opening statement determining the nature of the conversation is prepared that will indicate the purpose and topic of the Talanoa.…”