Preliminary findings on the role of high-frequency (5Hz) rTMS stimulation on M1 and pre-SMA regions in Parkinson's disease

Matching supplementary motor area-primary motor cortex paired transcranial magnetic stimulation improves motor dysfunction in Parkinson's disease: a single-center, double-blind randomized controlled clinical trial protocol

Background

Non-invasive neuroregulation techniques have been demonstrated to improve certain motor symptoms in Parkinson's disease (PD). However, the currently employed regulatory techniques primarily concentrate on stimulating single target points, neglecting the functional regulation of networks and circuits. The supplementary motor area (SMA) has a significant value in motor control, and its functionality is often impaired in patients with PD. The matching SMA-primary motor cortex (M1) paired transcranial magnetic stimulation (TMS) treatment protocol, which benefits patients by modulating the sequential and functional connections between the SMA and M1, was elucidated in this study.

Methods

This was a single-center, double-blind, randomized controlled clinical trial. We recruited 78 subjects and allocated them in a 1:1 ratio by stratified randomization into the paired stimulation (n = 39) and conventional stimulation groups (n = 39). Each patient underwent 3 weeks of matching SMA-M1 paired TMS or sham-paired stimulation. The subjects were evaluated before treatment initiation, 3 weeks into the intervention, and 3 months after the cessation of therapy. The primary outcome measure in this study was the Unified Parkinson's Disease Rating Scale III, and the secondary outcome measures included non-motor functional assessment, quality of life (Parkinson's Disease Questionnaire-39), and objective assessments (electromyography and functional near-infrared spectroscopy).

Discussion

Clinical protocols aimed at single targets using non-invasive neuroregulation techniques often improve only one function. Emphasizing the circuit and network regulation in PD is important for enhancing the effectiveness of TMS rehabilitation. Pairing the regulation of cortical circuits may be a potential treatment method for PD. As a crucial node in motor control, the SMA has direct fiber connections with basal ganglia circuits and complex fiber connections with M1, which are responsible for motor execution. SMA regulation may indirectly regulate the function of basal ganglia circuits. Therefore, the developed cortical pairing stimulation pattern can reshape the control of information flow from the SMA to M1. The novel neuroregulation model designed for this study is based on the circuit mechanisms of PD and previous research results, with a scientific foundation and the potential to be a means of neuroregulation for PD.Clinical trial registration: ClinicalTrials.gov, identifier [ChiCTR2400083325].

Theta burst stimulation on the fronto-cerebellar connective network promotes cognitive processing speed in the simple cognitive task

Background

The fronto-cerebellar functional network has been proposed to subserve cognitive processing speed. This study aims to elucidate how the long-range frontal-to-cerebellar effective connectivity contributes to faster speed.

Methods

In total, 60 healthy participants were randomly allocated to three five-daily sessions of transcranial magnetic stimulation conditions, namely intermittent theta-burst stimulation (iTBS, excitatory), continuous theta-burst stimulation (CTBS, inhibitory), or a sham condition. The sites of the stimulations were the right pre-supplementary motor area (RpSMA), medial cerebellar vermis VI (MCV6), and vertex, respectively. Performances in two reaction time tasks were recorded at different time points.

Results

Post-stimulation speeds revealed marginal decreases in the simple but not complex task. Nevertheless, participants in the excitatory RpSMA and inhibitory MCV6 conditions showed direct and negative path effects on faster speeds compared to the sham condition in the simple reaction time (SRT) task (β = -0.320, p = 0.045 and β = -0.414, p = 0.007, respectively). These path effects were not observed in the SDMT task.

Discussion

RpSMA and MCV6 were involved in promoting the path effects of faster reaction times on simple cognitive task. This study offers further evidence to support their roles within the long-range frontal-to-cerebellar connectivity subserving cognitive processing speed. The enhancement effects, however, are likely limited to simple rather than complex mental operations.

Comparative efficacy of transcranial magnetic stimulation on different targets in Parkinson's disease: A Bayesian network meta-analysis

Background/Objective

The efficacy of transcranial magnetic stimulation (TMS) on Parkinson's disease (PD) varies across the stimulation targets. This study aims to estimate the effect of different TMS targets on motor symptoms in PD.

Methods

A Bayesian hierarchical model was built to assess the effects across different TMS targets, and the rank probabilities and the surface under the cumulative ranking curve (SUCRA) values were calculated to determine the ranks of each target. The primary outcome was the Unified Parkinson's Disease Rating Scale part-III. Inconsistency between direct and indirect comparisons was assessed using the node-splitting method.

Results

Thirty-six trials with 1,122 subjects were included for analysis. The pair-wise meta-analysis results showed that TMS could significantly improve motor symptoms in PD patients. Network meta-analysis results showed that the high-frequency stimulation over bilateral M1, bilateral DLPFC, and M1+DLPFC could significantly reduce the UPDRS-III scores compared with sham conditions. The high-frequency stimulation over both M1 and DLPFC had a more significant effect when compared with other parameters, and ranked first with the highest SCURA value. There was no significant inconsistency between direct and indirect comparisons.

Conclusion

Considering all settings reported in our research, high-frequency stimulation over bilateral M1 or bilateral DLPFC has a moderate beneficial effect on the improvement of motor symptoms in PD (high confidence rating). High-frequency stimulation over M1+DLPFC has a prominent beneficial effect and appears to be the most effective TMS parameter setting for ameliorating motor symptoms of PD patients (high confidence rating).

Functional Connectivity of the Supplementary and Presupplementary Motor Areas in Postoperative Transition Between Stages of Frailty

BACKGROUND

Frailty is a multietiological geriatric syndrome of run-down physical reserves with high vulnerability to stressors. Transitions between physical robustness and frailty often occur in the context of medical interventions. Studies suggest that neurological disorders contribute to faster progression of frailty. In a previous cross-sectional study we found altered functional connectivity of supplementary motor area (SMA) in (pre)frail compared to robust patients. We analyzed functional connectivity of the SMA and presupplementary motor area (pre-SMA) in patients with postoperative transitions between physical robustness and stages of frailty.

METHODS

We investigated 120 cognitively healthy patients (49.2% robust, 47.5% prefrail, 3.3% frail, 37.5% female, median age 71 [65-87] years) undergoing elective surgery from the BioCog project, a multicentric prospective cohort study on postoperative delirium and cognitive dysfunction. Assessments took place 14 days before and 3 months after surgery, comprising assessments of a modified frailty phenotype according to Fried and resting-state functional magnetic resonance imaging at 3 T. The associations between functional connectivity of the SMA and pre-SMA networks, preoperative frailty stages, and postoperative transitions were examined using mixed linear effects models.

RESULTS

Nineteen patients showed physical improvement after surgery, 24 patients progressed to (pre)frailty and in 77 patients no transition was observed. At follow-up, 57 (47.5%) patients were robust, 52 (43.3%) prefrail, and 11 (9.2%) frail. Lower functional connectivity in the pre-SMA network was associated with more unfavorable postoperative transition types. An exploratory analysis suggested that the association was restricted to patients who were prefrail at baseline. There was no association of transition type with SMA functional connectivity in the primary analysis. In an exploratory analysis, transition from prefrailty to robustness was associated with higher functional connectivity and progression in robust patients was associated with higher SMA network segregation.

CONCLUSIONS

Our findings implicate that dysfunctions of cortical networks involved in higher cognitive control of motion are associated with postoperative transitions between frailty stages. The pre-SMA may be a target for neurofeedback or brain stimulation in approaches to prevent frailty. Clinical Trials Registration Number: NCT02265263.

Therapeutic Role of Repetitive Transcranial Magnetic Stimulation in Alzheimer’s and Parkinson’s Disease: Electroencephalography Microstate Correlates

Introduction

The microstate analysis is a method to convert the electrical potentials on the multi-channel electrode array to topographical electroencephalography (EEG) data. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive method that can modulate brain networks. This study explores the pathophysiological changes through microstate analysis in two different neurodegenerative diseases, Alzheimer’s (AD) and Parkinson’s disease (PD), characterized by motor and cognitive symptoms and analysis the effect of rTMS on the impaired cognitive and motor functions.

Materials and Methods

We included 18 AD, 8 PD patients, and 13 age-matched controls. For both groups, we applied 5 Hz rTMS on the left pre-SMA in PD patients while 20 Hz rTMS on the left lateral parietal region in AD patients. Each patient was re-evaluated 1 week after the end of the sessions, which included a detailed clinical evaluation and measurement of EEG microstates.

Results

At the baseline, the common findings between our AD and PD patients were altered microstate (MS) B, MS D durations and transition frequencies between MS A–MS B, MS C–MS D while global explained variance (GEV) ratio and the extent and frequency of occurrence of MS A, MS B, and MS D were separately altered in AD patients. Although no specific microstate parameter adequately differentiated between AD and PD patients, we observed significant changes in MS B and MS D parameters in PD patients. Further, we observed that Mini-Mental State Examination (MMSE) performances were associated with the transition frequencies between MS A–MS B and MS C–MS D and GEV ratio. After left parietal rTMS application, we have observed significantly increased visual memory recognition and clock drawing scores after left parietal rTMS application associated with improved microstate conditions prominent, especially in the mean duration of MS C in AD patients. Also, pre-SMA rTMS resulted in significant improvement in motor scores and frequency of transitions from MS D to MS C in PD patients.

Conclusion

This study shows that PD and AD can cause different and similar microstate changes that can be modulated through rTMS, suggesting the role of MS parameters and rTMS as a possible combination in monitoring the treatment effect in neurodegenerative diseases.

The Multifactorial Role of Pre-supplementary Motor Area Stimulation in the Freezing of Gait: An Alternative Strategy to the Classical Drug-Target Approach

INTRODUCTION

The pre-supplementary motor area (Pre-SMA) plays a pivotal role in the control of voluntary motor control and freezing of gait (FOG) pathophysiological mechanism. Here, we aimed to modulate if the pre-SMA would have beneficial effects on motor and behavioural outcomes in freezing of gait. To test this hypothesis, we examined the left pre-SMA stimulating effect of repetitive Transcranial Magnetic Stimulation (rTMS) on motor, cognitive and behavioural parameters in Parkinson's patients with FOG.

METHOD

The study included 20 Parkinson's patients with FOG (3 females, 17 males) who received the left Pre-SMA rTMS procedure. The clinical assessments were performed on all patients at the baseline and the patients were re-evaluated under the same clinical conditions one week after the end of the sessions.

RESULTS & DISCUSSION

We found significant improvements in motor, cognitive and behavioural symptoms (p<0.05). The main finding of our study is that Pre-SMA is an attractive stimulation area leading to critical improvement of symptoms of Parkinson' s patients with FOG.

CONCLUSION

The high-frequency rTMS stimulation over the left preSMA has a restorative effect on the motor, cognitive and behavioural symptoms of Parkinson' s patients with FOG.

Use of non-invasive stimulation in movement disorders: a critical review

BACKGROUND

Noninvasive stimulation has been widely used in the past 30 years to study and treat a large number of neurological diseases, including movement disorders.

OBJECTIVE

In this critical review, we illustrate the rationale for use of these techniques in movement disorders and summarize the best medical evidence based on the main clinical trials performed to date.

METHODS

A nationally representative group of experts performed a comprehensive review of the literature in order to analyze the key clinical decision-making factors driving transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) in movement disorders. Classes of evidence and recommendations were described for each disease.

RESULTS

Despite unavoidable heterogeneities and low effect size, TMS is likely to be effective for treating motor symptoms and depression in Parkinson's disease (PD). The efficacy in other movement disorders is unclear. TMS is possibly effective for focal hand dystonia, essential tremor and cerebellar ataxia. Additionally, it is likely to be ineffective in reducing tics in Tourette syndrome. Lastly, tDCS is likely to be effective in improving gait in PD.

CONCLUSIONS

There is encouraging evidence for the use of noninvasive stimulation on a subset of symptoms in selected movement disorders, although the means to optimize protocols for improving positive outcomes in routine clinical practice remain undetermined. Similarly, the best stimulation paradigms and responder profile need to be investigated in large clinical trials with established therapeutic and assessment paradigms that could also allow genuine long-term benefits to be determined.

New pharmacological and neuromodulation approaches for impulsive-compulsive behaviors in Parkinson's disease

INTRODUCTION

A significant proportion of patients with Parkinson's disease (PD) display a set of impulsive-compulsive behaviors at some point during the course of illness. These behaviors range from the so-called behavioral addictions to dopamine dysregulation syndrome, punding and hoarding disorders. These behaviors have been consistently linked to the use of dopaminergic medications used to treat PD motor symptoms (dopamine agonists, levodopa, and other agents) and less consistently to neuromodulation techniques such as deep brain stimulation (DBS). Since there are still no approved treatments for these conditions, their pharmacological management is still a big challenge for clinicians.

METHODS

We conducted an extensive review of current pharmacological and neuromodulation literature for the management of impulsive-compulsive disorders in PD patients.

RESULTS

Pharmacological treatment approaches for impulsive-compulsive behaviors and DDS in PD patients include reduction of levodopa (LD), reduction/cessation of dopamine agonist (DA), and initiation of infusion therapies (apomorphine infusion and duodopa). Also, atomoxetine, a noradrenergic agent approved for the treatment of attention deficit hyperactivity disorder, showed some interesting preliminary results but there is still a lack of controlled longitudinal studies. Finally, while DBS effects on impulsive-compulsive disorders are still controversial, non-invasive techniques (such as transcranial magnetic stimulation and transcranial direct current stimulation) could have a potential positive effect but, again, there is still a lack of controlled trials.

CONCLUSION

Managing impulsivity and compulsivity in PD patients is still a non-evidence-based challenge for clinicians. Controlled trials on promising approaches such as atomoxetine and non-invasive neuromodulation techniques are needed.