Intermittent Theta-Burst Stimulation Over the Suprahyoid Muscles Motor Cortex Facilitates Increased Degree Centrality in Healthy Subjects

50 Hz-Repetitive transcranial magnetic stimulation modulates brain connectivity in Parkinson's disease

OBJECTIVES

High-frequency repetitive transcranial magnetic stimulation (rTMS) may modulate neuronal excitability and promote the presumed "pro-kinetic" gamma frequency, while attenuating the "anti-kinetic" beta frequency. This study explores whether 50 Hz-rTMS and intermittent Theta Burst Stimulation (iTBS), of the primary motor (M1) and dorsolateral prefrontal cortex (DLPFC) enhance the gamma activity and functional connectivity within the motor circuit in Parkinson's disease (PD).

METHODS

We investigated pre- and post-rTMS interventional EEG in 62 PD patients following 50 Hz-rTMS and iTBS. Power spectral analysis, along with coherence and mutual information embedded in metrics of graph theory, was applied to assess the functional connectivity across the whole brain.

RESULTS

We found changes in the cluster coefficient and local efficiency of gamma activity in the left M1 following iTBS, and wider-spread changes within the sensorimotor circuit following 50 Hz-rTMS. We found no changes in the power spectrum or entrainment of the gamma activity in the motor cortex or beyond.

CONCLUSION

The current 50 Hz-rTMS protocols modulate functional connectivity in PD patients, but not the power spectrum. These topological changes do not translate into clinical effects. These stimulation protocols may lack the specificity to be clinically effective.

SIGNIFICANCE

High frequency rTMS provides new insights in brain connectivity in the gamma bandwidth.

Global research trends in transcranial magnetic stimulation for stroke (1994-2023): promising, yet requiring further practice

Background

Scholars have been committed to investigating stroke rehabilitation strategies over many years. Since its invention, transcranial magnetic stimulation (TMS) has been increasingly employed in contemporary stroke rehabilitation research. Evidence has shown the significant potential of TMS in stroke research and treatment.

Objective

This article reviews the research conducted on the use of TMS in stroke from 1994 to 2023. This study applied bibliometric analysis to delineate the current research landscape and to anticipate future research hotspots.

Method

The study utilized the Web of Science Core Collection to retrieve and acquire literature data. Various software tools, including VOSviewer (version 1.6.19), CiteSpace (version 6.3.R1), Scimago Graphica (version 1.0.36), and WPS (version 11572), were used for data analysis and visualization. The review included analyses of countries, institutions, authors, journals, articles, and keywords.

Results

A total of 3,425 articles were collected. The top three countries in terms of publication output were the United States (953 articles), China (546 articles), and Germany (424 articles). The United States also had the highest citation counts (56,764 citations), followed by Germany (35,211 citations) and the United Kingdom (32,383 citations). The top three institutions based on the number of publications were Harvard University with 138 articles, the University of Auckland with 81 articles, and University College London with 80 articles. The most prolific authors were Abo, Masahiro with 54 articles, Fregni, Felipe with 53 articles, and Pascual-Leone, Alvaro with 50 articles. The top three journals in terms of article count were Neurorehabilitation and Neural Repair with 139 articles, Clinical Neurophysiology with 128 articles, and Frontiers in Neurology with 110 articles. The most frequently occurring keywords were stroke (1,275 occurrences), transcranial magnetic stimulation (1,119 occurrences), and rehabilitation (420 occurrences).

Conclusion

The application of TMS in stroke research is rapidly gaining momentum, with the USA leading in publications. Prominent institutions, such as Harvard University and University College London, show potential for collaborative research. The key areas of focus include post-stroke cognitive impairment, aphasia, and dysphagia, which are expected to remain significant hotspots in future research. Future research should involve large-scale, randomized, and controlled trials in these fields. Additionally, identifying more effective combined therapies with rTMS should be a priority.

A systematic review of the neurobiological effects of theta-burst stimulation (TBS) as measured using functional magnetic resonance imaging (fMRI)

Theta burst stimulation (TBS) is associated with the modulation of a range of clinical, cognitive, and behavioural outcomes, but specific neurobiological effects remain somewhat unclear. This systematic literature review investigated resting-state and task-based functional magnetic resonance imaging (fMRI) outcomes post-TBS in healthy human adults. Fifty studies that applied either continuous-or intermittent-(c/i) TBS, and adopted a pretest-posttest or sham-controlled design, were included. For resting-state outcomes following stimulation applied to motor, temporal, parietal, occipital, or cerebellar regions, functional connectivity generally decreased in response to cTBS and increased in response to iTBS, though there were some exceptions to this pattern of response. These findings are mostly consistent with the assumed long-term depression (LTD)/long-term potentiation (LTP)-like plasticity effects of cTBS and iTBS, respectively. Task-related outcomes following TBS were more variable. TBS applied to the prefrontal cortex, irrespective of task or state, also produced more variable responses, with no consistent patterns emerging. Individual participant and methodological factors are likely to contribute to the variability in responses to TBS. Future studies assessing the effects of TBS via fMRI must account for factors known to affect the TBS outcomes, both at the level of individual participants and of research methodology.

Bilateral Cerebellar Intermittent Theta Burst Stimulation Combined With Swallowing Speech Therapy for Dysphagia After Stroke: A Randomized, Double-Blind, Sham-Controlled, Clinical Trial

BACKGROUND

Previous studies have found that high-frequency repetitive transcranial magnetic stimulation (rTMS) of the cerebellar hemisphere could improve swallowing function, but whether intermittent theta burst stimulation (iTBS), which has similar excitatory effect and higher efficiency, can also improve swallowing function for dysphagia after stroke remains unclear.

OBJECTIVE

This trial aimed to explore the efficacy and safety of bilateral cerebellar transcranial magnetic stimulation with iTBS for dysphagia after stroke.

METHODS

Seventy patients with dysphagia after stroke were divided into 2 treatment groups: true bilateral cerebellar iTBS and sham bilateral cerebellar iTBS. The true iTBS group underwent ten 100% resting motor threshold (RMT) iTBS sessions for 2 weeks. In the sham iTBS group, the parameters were the same except that the figure-eight coil was perpendicular to the skull. Both groups received traditional swallowing rehabilitation treatment 5 times a week for 2 weeks. Swallowing function was assessed with the Fiberoptic Endoscopic Dysphagia Severity Scale (FEDSS), Penetration/Aspiration Scale (PAS), Standardized Swallowing Assessment (SSA), and Functional Oral Intake Scale (FOIS) at baseline, 2 weeks after the intervention, and at 4 weeks of follow-up.

RESULTS

There were significant time and group interaction effects in both multi-factorial adjusted and unadjusted FEDSS, PAS, SSA, and FOIS score (P < .001). In the pairwise comparison of the swallowing parameters among the 2 groups, the FEDSS, PAS, SSA, and FOIS scores at 2 weeks and 4 weeks showed a significantly higher improvement in the iTBS simulation group than sham group (P < .05). In both the true iTBS and sham iTBS stimulation groups, all FEDSS, PAS, SSA, and FOIS scores were significantly improved over time (P < .001).

CONCLUSIONS

The present study suggested that as a more efficient TMS stimulation mode, iTBS could efficiently improve swallowing function by stimulating the bilateral cerebellar hemisphere. In addition, 100% resting motor threshold bilateral cerebellar iTBS is a relatively safe treatment.

CLINICAL TRIAL REGISTRATION

Effect analysis of repeated transcranial magnetic stimulation of cerebellar on dysphagia after stroke. www.chictr.org.cn. Identifier: ChiCTR2100042092.

Theta burst stimulation versus high-frequency repetitive transcranial magnetic stimulation for poststroke dysphagia: A randomized, double-blind, controlled trial

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) of high-frequency (10 Hz) on suprahyoid motor cortex has been an evidence-based treatment for poststroke dysphagia. Intermittent theta burst stimulation (iTBS) can be performed in 3 minutes compared with 20 ± 5 minutes for 10 Hz rTMS. This study aimed to ensure the clinical efficacy, safety, and tolerability of iTBS compared with 10 Hz rTMS for patients with poststroke dysphagia.

METHOD

In this randomized, double-blind, single-center, controlled trial, 47 participants were randomly assigned to iTBS (n = 24) and rTMS (n = 23) group. Each participant received iTBS or rTMS daily at suprahyoid motor cortex of affected hemisphere for 10 consecutive days. The outcomes were assessed at baseline, immediately, and 2 weeks after intervention, including water-swallowing test, standardized swallowing assessment, Mann assessment of swallowing ability, Murray Secretion Scale, Yale Pharyngeal Residue Severity Rating Scale, Penetration-Aspiration Scale, and motor evoked potential (MEP) of bilateral suprahyoid muscle.

RESULTS

There were no significant differences between groups. There was a significant improvement on all rating scales and MEP after rTMS and iTBS. No significant differences on water-swallowing test, Mann assessment of swallowing ability, standardized swallowing assessment, Murray Secretion Scale scores, and MEP were observed between groups. In particular, there was significant differences on Penetration-Aspiration Scale scores (viscous liquid: mean difference = 1.016; 95% CI: 0.32-1.71; effect size: 0.360; P = .005) and the residue rate of pyriform fossa (viscous liquid: mean difference = 0.732; 95% CI: 0.18-1.28; effect size: 0.248; P = .010) in between-group. Comparing the differences over the changes of all rating scales, only the residue rate of epiglottis valley between groups was found to be significantly different (dilute liquid: mean difference = -0.567; 95% CI: -0.98 to -0.15; P = .009). There was no severe adverse effect and high dropout rates in both groups.

CONCLUSION

The clinical efficacy, safety, and tolerability of iTBS showed non-inferior to 10 Hz rTMS for patients with poststroke dysphagia. The present study can be used to improve the clinicians' knowledge and clinical decision skills on iTBS and rTMS for poststroke dysphagia.