Daily repetitive transcranial magnetic stimulation of primary motor cortex for neuropathic pain: a randomized, multicenter, double-blind, crossover, sham-controlled trial

Management of Central Post-Stroke Pain: Systematic Review and Meta-Analysis

Central post stroke pain (CPSP) is a neuropathic pain condition prevalent in 8% to 35% of stroke patients. This systematic review and meta-analysis aimed to provide insight in the effectiveness of available pharmacological, physical, psychological, and neuromodulation intervention in reducing pain in CPSP patients (PROSPERO Registration: CRD42022371835). Secondary outcomes included mood, sleep, global impression of change, and physical responses. Data extraction included participant demographics, stroke aetiology, pain characteristics, pain reduction scores, and secondary outcome metrics. Forty two original studies were included with a total of 1451 participants. No studies providing psychological therapy to CPSP patients were identified. Twelve studies met requirements for a random-effects meta-analyses that found: pharmacological therapy to have a small effect on mean pain score (SMD = -0.36, 96.0% Confidence Interval [-0.68, -0.03], physical interventions did not show a significant effect (SMD = -0.55, [-1.28, 0.18]), and neuromodulation treatments had a moderate effect (SMD -0.64, [-1.08, -0.19]). Fourteen studies were included in proportional meta-analysis with pharmacological studies having a moderate effect (58.3% mean pain reduction, [-36.51, -80.15]), and neuromodulation studies a small effect (31.1% mean pain reduction, [-43.45, -18.76]). Sixteen studies were included in the narrative review, findings from which largely supported meta-analyses results. Duloxetine, Amitriptyline and repetitive Transcranial Magnetic Stimulation (rTMS) had the most robust evidence for their effectiveness in alleviating CPSP induced pain. Further multi-centre placebo-controlled research is needed to ascertain the effectiveness of physical therapies, such as acupuncture and virtual reality, and invasive and non-invasive neuromodulation treatments. PERSPECTIVE: This article presents a top-down and bottom-up overview of evidence for the effectiveness of different pharmacological, physical, and neuromodulation treatments of CPSP. This review could provide clinicians with a comprehensive understanding of the effectiveness and tolerability of different treatment types.

Exploring the use of bimodal transcranial direct current stimulation to enhance movement in individuals with patellofemoral pain-A sham-controlled double blinded pilot study

Introduction

In individuals with patellofemoral pain (PFP), addressing increased knee valgus during weight-bearing activities typically involves strengthening weak hip muscles. However, recent literature highlights the role of altered descending central control in abnormal movements associated with PFP. While transcranial direct current stimulation (tDCS) has demonstrated the capacity to enhance neuroplasticity, its application targeting the corticomotor function of gluteal muscles in PFP remains unexplored. This study aimed to investigate the effects of combining bimodal tDCS with exercise on frontal plane kinematics in individuals with PFP. The hypothesis was that bimodal tDCS, specifically targeting the corticomotor function of the gluteal muscles, would augment the effectiveness of exercise interventions in improving frontal plane kinematics compared to sham stimulation.

Methods

Ten participants with PFP participated in two sessions involving either bimodal tDCS or sham stimulation, concurrently with hip strengthening exercises. Weight-bearing tasks, including single leg squat, single leg landing, single leg hopping, forward step-down, and lateral step-down, were performed and recorded before and after each session. Pain visual analog scale (VAS) scores were also documented. A one-way ANOVA with repeated measures was employed to compare kinematics, while a Friedman test was used to compare VAS across the three conditions (pre-test, post-tDCS, and post-Sham).

Results

We observed no significant differences in trunk lean angle, hip and knee frontal plane projection angles, or dynamic valgus index among the three conditions during the five weight-bearing tasks. VAS scores did not differ across the three conditions.

Discussion and conclusion

A single session of tDCS did not demonstrate immediate efficacy in enhancing frontal plane kinematics or relieving pain in individuals with PFP. Considering observed positive outcomes in other neurological and orthopedic populations with multi-session tDCS applications, suggesting potential cumulative effects, further research is essential to explore the effects of multi-session tDCS on weight-bearing movement and underlying neurophysiology in individuals with PFP.

Assessing the effectiveness of high frequency repetitive transcranial magnetic stimulation for post-mastectomy pain in breast cancer patients: A randomized controlled trial

BACKGROUND

Post-mastectomy pain Syndrome (PMPS), characterized by chronic neuropathic pain stemming from intercostobrachial nerve lesions, presents a formidable clinical challenge. With the incidence of breast cancer surging, effective interventions for PMPS are urgently needed. To address this, we conducted this double-blind, placebo-controlled, randomized clinical trial to study the efficacy of repetitive Transcranial Magnetic Stimulation (rTMS) therapy over the motor cortex on pain, quality of life and thermal sensitivity in PMPS patients.

METHODS

We delivered 15 rTMS sessions over three weeks in a cohort of 34 PMPS patients. These patients were allocated randomly to either rTMS therapy or sham therapy groups. Pain assessments, utilizing the Visual Analogue Scale (VAS) and Short Form McGill Pain Questionnaire (SF-MPQ), alongside quality-of-life evaluations through the Functional Assessment of Cancer Therapy-Breast (FACT-B), were recorded before and after the 15 sessions. Additionally, we assessed thermal sensitivity using Quantitative Sensory Testing (QST).

RESULTS

Our findings demonstrate the superior efficacy of rTMS therapy (over sham therapy) in reducing VAS and SF-MPQ scores (p < 0.0001), improving physical (p = 0.037), emotional (p = 0.033), and functional well-being (p = 0.020) components of quality of life, as quantified by FACT-B. Our investigation also unveiled marked enhancements in thermal sensitivity within the rTMS therapy group, with statistically significant improvements in cold detection threshold (p = 0.0001), warm detection threshold (p = 0.0033), cold pain threshold (p = 0.0078), and hot pain tolerance threshold (p = 0.0078).

CONCLUSION

The study underscores the profound positive impact of rTMS therapy on pain, quality of life, and thermal sensitivity in patients having PMPS, opening new avenues for pain management strategies.

Non-invasive TMS attenuates neuropathic pain after spinal cord injury associated with enhancing brain functional connectivity and HPA axis activity

Patients with spinal cord injury (SCI) often suffer from varying degrees of neuropathic pain. Non-invasive repetitive transcranial magnetic stimulation (TMS) has been shown to improve neuropathic pain, while the appropriate intervention strategies of TMS treatment and how TMS affects brain function after SCI were not entirely clear. To investigate the effects and mechanisms of TMS on neuropathic pain after SCI, high-frequency TMS on primary motor cortex (M1) of mice was performed after SCI and pain response was evaluated through an electronic Von-Frey device and cold/hot plates. Functional magnetic resonance imaging (fMRI), bulk RNA sequencing, immunofluorescence and molecular experiments were used to evaluate brain and spinal cord function changes and mechanisms. TMS significantly improved SCI induced mechanical allodynia, cold and thermal hyperalgesia with a durative effect, and TMS intervention at 1 week after SCI had pain relief advantages than at 2 weeks. TMS intervention not only affected the functional connections between the primary motor cortex and the thalamus, but also increased the close connection of multiple brain regions. Importantly, TMS treatment activated the hypothalamic pituitary adrenal (HPA) axis and increased the transcript levels of genes encode hormone proteins, accompanied with the attenuation of inflammatory microenvironment in spinal cord associated with pain relief. Totally, these results elucidate that early intervention with TMS could improve neuropathic pain after SCI associated with enhancing brain functional connectivity and HPA axis activity which should be harnessed to modulate neuropathic pain after SCI.

Brain activity changes after high/low frequency stimulation in a nonhuman primate model of central post-stroke pain

Central post-stroke pain (CPSP) is a chronic pain resulting from a lesion in somatosensory pathways. Neuromodulation techniques, such as repetitive transcranial magnetic stimulation (rTMS) that target the primary motor cortex (M1), have shown promise for the treatment of CPSP. High-frequency (Hf) rTMS exhibits analgesic effects compared to low-frequency (Lf) rTMS; however, its analgesic mechanism is unknown. We aimed to elucidate the mechanism of rTMS-induced analgesia by evaluating alterations of tactile functional magnetic resonance imaging (fMRI) due to Hf- and Lf-rTMS in a CPSP monkey model. Consistent with the patient findings, the monkeys showed an increase in pain threshold after Hf-rTMS, which indicated an analgesic effect. However, no change after Lf-rTMS was observed. Compared to Lf-rTMS, Hf-rTMS produced enhanced tactile-evoked fMRI signals not only in M1 but also in somatosensory processing regions, such as the primary somatosensory and midcingulate cortices. However, the secondary somatosensory cortex (S2) was less active after Hf-rTMS than after Lf-rTMS, suggesting that activation of this region was involved in CPSP. Previous studies showed pharmacological inhibition of S2 reduces CPSP-related behaviors, and the present results emphasize the involvement of an S2 inhibitory system in rTMS-induced analgesia. Verification using the monkey model is important to elucidate the inhibition system.

Repetitive transcranial magnetic stimulation focusing on patients with neuropathic pain in the upper limb: a randomized sham-controlled parallel trial

This study aimed to evaluate the efficacy and safety of navigation-guided repetitive transcranial magnetic stimulation (rTMS) over the primary motor cortex in patients with neuropathic pain in the upper limb. This randomized, blinded, sham-controlled, parallel trial included a rTMS protocol (10-Hz, 2000 pulses/session) consisting of five daily sessions, followed by one session per week for the next seven weeks. Pain intensity, as well as pain-related disability, quality of life, and psychological status, were assessed. For the primary outcome, pain intensity was measured daily using a numerical rating scale as a pain diary. Thirty patients were randomly assigned to the active rTMS or sham-stimulation groups. In the primary outcome, the decrease (least square [LS] mean ± standard error) in the weekly average of a pain diary at week 9 compared to the baseline was 0.84 ± 0.31 in the active rTMS group and 0.58 ± 0.29 in the sham group (LS mean difference, 0.26; 95% confidence interval, - 0.60 to 1.13). There was no significant effect on the interaction between the treatment group and time point. Pain-related disability score improved, but other assessments showed no differences. No serious adverse events were observed. This study did not show significant pain relief; however, active rTMS tended to provide better results than sham. rTMS has the potential to improve pain-related disability in addition to pain relief.Clinical Trial Registration number: jRCTs052190110 (20/02/2020).

Field recordings of transcranial magnetic stimulation in human brain postmortem models

Introduction

The ability of repetitive transcranial magnetic stimulation (rTMS) to deliver a magnetic field (MF) in deep brain targets is debated and poorly documented.

Objective

To quantify the decay of MF in the human brain.

Methods

Magnetic field was generated by single pulses of TMS delivered at maximum intensity using a flat or angulated coil. Magnetic field was recorded by a 3D-magnetic probe. Decay was measured in the air using both coils and in the head of 10 postmortem human heads with the flat coil being positioned tangential to the scalp. Magnetic field decay was interpreted as a function of distance to the coil for 6 potential brain targets of noninvasive brain stimulation: the primary motor cortex (M1, mean depth: 28.5 mm), dorsolateral prefrontal cortex (DLPFC: 28 mm), secondary somatosensory cortex (S2: 35.5 mm), posterior and anterior insulae (PI: 38.5 mm; AI: 43.5 mm), and midcingulate cortex (MCC: 57.5 mm).

Results

In air, the maximal MF intensities at coil center were 0.88 and 0.77 T for the flat and angulated coils, respectively. The maximal intracranial MF intensity in the cadaver model was 0.34 T, with a ∼50% decay at 15 mm and a ∼75% MF decay at 30 mm. The decay of the MF in air was similar for the flat coil and significantly less attenuated with the angulated coil (a ∼50% decay at 20 mm and a ∼75% MF decay at 45 mm).

Conclusions

Transcranial magnetic stimulation coil MFs decay in brain structures similarly as in air, attenuation with distance being significantly lower with angulated coils. Reaching brain targets deeper than 20 mm such as the insula or Antérior Cingulate Cortex seems feasible only when using angulated coils. The abacus of MF attenuation provided here can be used to adjust modalities of deep brain stimulation with rTMS in future research protocols.

Optimal Frequency in Repetitive Transcranial Magnetic Stimulation for the Management of Chronic Pain: A Network Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

Repetitive Transcranial Magnetic Stimulation (rTMS) has been shown to be effective for pain modulation in a variety of pathological conditions causing neuropathic pain. The purpose of this study is to conduct a network meta-analysis (NMA) of randomized control trials to identify the most optimal frequency required to achieve chronic pain modulation using rTMS.

METHODS

A comprehensive search was conducted in electronic databases to identify randomized controlled trials investigating the efficacy of rTMS for chronic pain management. A total of 24 studies met the inclusion criteria, and a NMA was conducted to identify the most effective rTMS frequency for chronic pain management.

RESULTS

Our analysis revealed that high frequency rTMS (20 Hz) was the most effective frequency for chronic pain modulation. Patients treated with 20 Hz had lower pain levels than those treated at 5 Hz (mean difference [MD] = -3.11 [95% confidence interval {CI}: -5.61 - -0.61], P = 0.032) and control (MD = -1.99 [95% CI: -3.11 - -0.88], P = 0.023). Similarly, treatment with 10 Hz had lower pain levels compared to 5 Hz (MD = -2.56 [95% CI: -5.05 - -0.07], P = 0.045) and control (MD = -1.44 [95% CI: -2.52 - -0.36], P = 0.031). 20 Hz and 10 Hz were not statistically different.

CONCLUSIONS

This NMA suggests that high frequency rTMS (20 Hz) is the most optimal frequency for chronic pain modulation. These findings have important clinical implications and can guide healthcare professionals in selecting the most effective frequency for rTMS treatment in patients with chronic pain.

Serial changes in diffusion tensor imaging metrics and therapeutic effects of repetitive transcranial magnetic stimulation in post-traumatic headache and depression: A case report

BACKGROUND

Mild traumatic brain injury patients commonly complain headache and central pain, and the pain accompanies depressive mood change. This case study reports the therapeutic effect of repetitive transcranial magnetic stimulation (rTMS) in mild traumatic brain injury patient with headache and depression through objective serial changes of diffusion tensor imaging (DTI).

METHODS

The 51-year-old man complained of headache and depression despite conventional treatment for 13 months. We applied 15 times rTMS on the left dorsolateral prefrontal cortex. We checked the pain and depression through numeric rating scale (NRS) and Beck depression inventory (BDI) when admission, discharged, and 1 month after discharge. DTI was performed 3 times; before, during-day of rTMS 6th stimulation, and after-day of rTMS 15th stimulation. Then the reconstructed White matter related to pain and depression was obtained.

RESULTS

NRS and BDI showed significant improvement and it was maintained 1 year after discharge. DTI-based metrics of the White matters related to pain and depression gradually increased before - during - after rTMS.

CONCLUSION

Studies focused on examining changes in pain, depression and DTI-based metrics of White matter are rare. This case is significant in that not only pain and depression improved after the rTMS, but also serial changes in White matter were observed in DTI.

Catgut embedding in acupoints combined with repetitive transcranial magnetic stimulation for the treatment of postmenopausal osteoporosis: study protocol for a randomized clinical trial

Background

To date, the clinical modulation for bone metabolism based on the neuro-bone mass regulation theory is still not popular. The stimulation of nerve systems to explore novel treatments for Postmenopausal osteoporosis (PMOP) is urgent and significant. Preliminary research results suggested that changes brain function and structure may play a crucial role in bone metabolism with PMOP. Thus, we set up a clinical trial to investigate the effect of the combination of repetitive transcranial magnetic stimulation (rTMS) and catgut embedding in acupoints (CEA) for PMOP and to elucidate the central mechanism of this neural stimulation in regulating bone metabolism.

Method

This trial is a prospective and randomized controlled trial. 96 PMOP participants will be randomized in a 1:1:1 ratio into a CEA group, an rTMS group, or a combined one. Participants will receive CEA, rTMS, or combined therapy for 3 months with 8 weeks of follow-up. The primary outcomes will be the changes in Bone Mineral Density scores, total efficiency of Chinese Medicine Symptoms before and after treatment. Secondary outcomes include the McGill Pain Questionnaire Short-Form, Osteoporosis Symptom Score, Mini-Mental State Examination, and Beck Depression Inventory-II. The leptin, leptin receptor, and norepinephrine levels of peripheral blood must be measured before and after treatment. Adverse events that occur during the trial will be recorded.

Discussion

CEA achieves brain-bone mass regulation through the bottom-up way of peripheral-central while rTMS achieves it through the top-down stimulation of central-peripheral. CEA combined with rTMS can stimulate the peripheral-central at the same time and promote peripheral bone mass formation. The combination of CEA and rTMS may play a coordinating, synergistic, and side-effect-reducing role, which is of great clinical significance in exploring better treatment options for PMOP.Clinical trial registration: https://www.chictr.org.cn/, identifier ChiCTR2300073863.

Evaluation of the Effect of Repetitive Transcranial Magnetic Stimulation of Motor Cortex on Failed Back Surgery Syndrome Pain Control in the Short Term

BACKGROUND

 This study aimed to evaluate the short-term efficacy of repetitive transcranial magnetic stimulation (rTMS) on the treatment of failed back surgery syndrome (FBSS).

METHODS

 In this prospective clinical trial study, 13 patients with FBSS were selected to undergo rTMS, including 5 sessions of stimulation of the primary motor cortex of 90 trains with a frequency of 10 Hz for 2 seconds and an intertrain interval of 20 seconds with a total pulse rate of 1800 per session. The time of each session was 30 minutes with an intensity of 80% of the motor threshold. The severity of pain before and after the intervention was measured by the short-form McGill Pain Questionnaire and visual analog scale (VAS).

RESULTS

 The mean of pain severity was 26.54 ± 6.78 and 14.92 ± 10.1 before and after rTMS, respectively. The severity of pain was significantly decreased after the intervention (p = 0.001). According to the McGill Pain Questionnaire, the severity of pain in the patients was decreased by 44.09 ± 27.32. The mean of the severity of pain according to VAS was 77.31 ± 16.66 before rTMS and 53.46 ± 22.49 after rTMS, which showed that pain intensity was significantly decreased after the intervention (p = 0.006).

CONCLUSIONS

 The use of rTMS of the primary motor cortex in patients who have undergone lumbosacral spine surgery and suffer from pain related to FBSS is associated with a significant reduction in the severity of pain. Because rTMS is a noninvasive treatment method, it can be used as a suitable treatment in these patients.

Design and Validation of Miniaturized Repetitive Transcranial Magnetic Stimulation (rTMS) Head Coils

Repetitive transcranial magnetic stimulation (rTMS) is a rapidly developing therapeutic modality for the safe and effective treatment of neuropsychiatric disorders. However, clinical rTMS driving systems and head coils are large, heavy, and expensive, so miniaturized, affordable rTMS devices may facilitate treatment access for patients at home, in underserved areas, in field and mobile hospitals, on ships and submarines, and in space. The central component of a portable rTMS system is a miniaturized, lightweight coil. Such a coil, when mated to lightweight driving circuits, must be able to induce B and E fields of sufficient intensity for medical use. This paper newly identifies and validates salient theoretical considerations specific to the dimensional scaling and miniaturization of coil geometries, particularly figure-8 coils, and delineates novel, key design criteria. In this context, the essential requirement of matching coil inductance with the characteristic resistance of the driver switches is highlighted. Computer simulations predicted E- and B-fields which were validated via benchtop experiments. Using a miniaturized coil with dimensions of 76 mm × 38 mm and weighing only 12.6 g, the peak E-field was 87 V/m at a distance of 1.5 cm. Practical considerations limited the maximum voltage and current to 350 V and 3.1 kA, respectively; nonetheless, this peak E-field value was well within the intensity range, 60-120 V/m, generally held to be therapeutically relevant. The presented parameters and results delineate coil and circuit guidelines for a future miniaturized, power-scalable rTMS system able to generate pulsed E-fields of sufficient amplitude for potential clinical use.

Transcranial magnetic stimulation therapy for central post-stroke pain: systematic review and meta-analysis

Introduction

Although rare, central post-stroke pain remains one of the most refractory forms of neuropathic pain. It has been reported that repetitive transcranial magnetic stimulation (rTMS) may be effective in these cases of pain.

Aim

The aim of this study was to investigate the efficacy of rTMS in patients with central post-stroke pain (CPSP).

Methods

We included randomized controlled trials or Controlled Trials published until October 3rd, 2022, which studied the effect of rTMS compared to placebo in CPSP. We included studies of adult patients (>18 years) with a clinical diagnosis of stroke, in which the intervention consisted of the application of rTMS to treat CSP.

Results

Nine studies were included in the qualitative analysis; 6 studies (4 RCT and 2 non-RCT), with 180 participants, were included in the quantitative analysis. A significant reduction in CPSP was found in favor of rTMS compared with sham, with a large effect size (SMD: -1.45; 95% CI: -1.87; -1.03; p < 0.001; I2: 58%).

Conclusion

The findings of the present systematic review with meta-analysis suggest that there is low quality evidence for the effectiveness of rTMS in reducing CPSP.

Systematic review registration

Identifier (CRD42022365655).

Beyond trial-and-error: Individualizing therapeutic transcranial neuromodulation for chronic pain

BACKGROUND AND OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) applied to the motor cortex provides supplementary relief for some individuals with chronic pain who are refractory to pharmacological treatment. As rTMS slowly enters treatment guidelines for pain relief, its starts to be confronted with challenges long known to pharmacological approaches: efficacy at the group-level does not grant pain relief for a particular patient. In this review, we present and discuss a series of ongoing attempts to overcome this therapeutic challenge in a personalized medicine framework.

DATABASES AND DATA TREATMENT

Relevant scientific publications published in main databases such as PubMed and EMBASE from inception until March 2023 were systematically assessed, as well as a wide number of studies dedicated to the exploration of the mechanistic grounds of rTMS analgesic effects in humans, primates and rodents.

RESULTS

The main strategies reported to personalize cortical neuromodulation are: (i) the use of rTMS to predict individual response to implanted motor cortex stimulation; (ii) modifications of motor cortex stimulation patterns; (iii) stimulation of extra-motor targets; (iv) assessment of individual cortical networks and rhythms to personalize treatment; (v) deep sensory phenotyping; (vi) personalization of location, precision and intensity of motor rTMS. All approaches except (i) have so far low or moderate levels of evidence.

CONCLUSIONS

Although current evidence for most strategies under study remains at best moderate, the multiple mechanisms set up by cortical stimulation are an advantage over single-target 'clean' drugs, as they can influence multiple pathophysiologic paths and offer multiple possibilities of individualization.

SIGNIFICANCE

Non-invasive neuromodulation is on the verge of personalised medicine. Strategies ranging from integration of detailed clinical phenotyping into treatment design to advanced patient neurophysiological characterisation are being actively explored and creating a framework for actual individualisation of care.

Effects of different transcranial magnetic stimulations on neuropathic pain after spinal cord injury

Introduction

Repetitive transcranial magnetic stimulation (rTMS) is an effective non-invasive cortical stimulation technique in the treatment of neuropathic pain. As a new rTMS technique, intermittent theta burst stimulation (iTBS) is also effective at relieving pain. We aimed to establish the pain-relieving effectiveness of different modalities on neuropathic pain. The study was conducted in individuals with spinal cord injury (SCI) and different modalities of rTMS.

Methods

Thirty-seven individuals with SCI were randomly allocated to three groups, in which the "iTBS" group received iTBS, the "rTMS" group received 10 Hz rTMS, and the "iTBS + rTMS" group received iTBS and 10 Hz rTMS successively of the primary motor cortex 5 days a week for 4 weeks, and they all underwent the full procedures. The primary outcome measure was change in the visual analog scale (VAS), and the secondary outcomes were measured using the Hamilton Rating Scale for Depression (HAM-D) and the Pittsburgh Sleep Quality Index (PSQI). All the outcomes were evaluated at 1 day before stimulation (baseline), 1 day after the first week of stimulation (S1), and 1 day after the last stimulation (S2).

Results

The VAS scores showed significant pain improvement after 4 weeks of stimulation (p = 0.0396, p = 0.0396, and p = 0.0309, respectively) but not after 1 week of stimulation. HAM-D scores declined, but the decreases were not significant until 4 weeks later (p = 0.0444, p = 0.0315, and p = 0.0447, respectively). PSQI scores were also significantly decreased after 4 weeks of stimulation (p = 0.0446, p = 0.0244, and p = 0.0088, respectively). Comparing the three modalities, VAS, HAM-D, and PSQI scores at S1 showed no differences, and, at S2, VAS scores showed significant differences (p = 0.0120; multiple comparisons showed significant differences between iTBS and iTBS + rTMS, p = 0.0091), while the HAM-D and PSQI scores showed no differences.

Discussion

The primary and secondary outcomes all showed significant improvement, indicating that the three different modalities were all effective at relieving the pain. However, not all the three stimulations were of same effectiveness after treatment; there were statistical differences in the treatment of neuropathic pain between iTBS as a priming stimulus and as a single procedure.

Cerebellar repetitive transcranial magnetic stimulation modulates the motor learning of visually guided voluntary postural control task

We investigated whether vermal cerebellar low-frequency repetitive transcranial magnetic stimulation (crTMS) affects motor learning of visually guided postural tracking training (VTT) using foot center of pressure (COP) as well as the stability and sensory contribution of upright standing. Twenty-one healthy volunteers participated (10 in the sham-crTMS group and 11 in the active-crTMS group). For VTT, participants stood on the force plate 1.5 m from the monitor on which the COP and target moved in a circle. Participants tracked the target with their own COP for 1 min, and 10 VTT sessions were conducted. The tracking error (TE) was compared between trials. Active- or sham-crTMS sessions were conducted prior to VTT. At baseline (before crTMS), pre-VTT (after crTMS), and post-VTT, the COP trajectory during upright static standing under four conditions (eyes, open/closed; surface, hard/rubber) was recorded. Comparison of the length of the COP trajectory or path and sensory-contribution-rate showed no significant difference between baseline and pre- and post-VTT. There was a significant decrease in TE in the sham-crTMS but not in the active-crTMS group. VTT and crTMS did not immediately affect the stability and sensory contribution of upright standing; however, crTMS immediately affected motor learning. The vermal cerebellum may contribute to motor learning of voluntary postural control.

Research Hotspots and Effectiveness of Transcranial Magnetic Stimulation in Pain: A Bibliometric Analysis

Transcranial magnetic stimulation, as a relatively new type of treatment, is a safe and non-invasive method for pain therapy. Here, we used CiteSpace software to visually analyze 440 studies concerning transcranial magnetic stimulation in pain research from 2010 to 2021, indexed by Web of Science, to clarify the research hotspots in different periods and characterize the process of discovery in this field. The United States ranked first in this field. Lefaucheur JP, Fregni F, and Andrade ACD made great contributions to this field of study. The most prolific institution was University of São Paulo. The four main hot keywords were neuropathic pain, motor cortex, connectivity, and non-invasive brain stimulation. There were three main points that were generally accepted: (1) definite analgesic effect of high-frequency rTMS of M1 contralateral to pain side in neuropathic pain; (2) there are inconclusive recommendations regarding rTMS of the dorsolateral prefrontal cortex (DLPFC) in fibromyalgia and neuropathic pain; (3) there is low-quality evidence that single doses of high-frequency rTMS of the motor cortex may have short-term effects on chronic pain. This bibliometric analysis indicated that prospective, multi-center, large-sample, randomized controlled trials are still needed to further verify the effectiveness of various transcranial magnetic stimulation parameters in pain research.

Analgesic Effects of Repetitive Transcranial Magnetic Stimulation at Different Stimulus Parameters for Neuropathic Pain: A Randomized Study

OBJECTIVES

The aim of the present study was to investigate the analgesic effects of repetitive transcranial magnetic stimulation over the primary motor cortex (M1-rTMS) using different stimulation parameters to explore the optimal stimulus condition for treating neuropathic pain.

MATERIALS AND METHODS

We conducted a randomized, blinded, crossover exploratory study. Four single sessions of M1-rTMS at different parameters were administered in random order. The tested stimulation conditions were as follows: 5-Hz with 500 pulses per session, 10-Hz with 500 pulses per session, 10-Hz with 2000 pulses per session, and sham stimulation. Analgesic effects were assessed by determining the visual analog scale (VAS) pain intensity score and Short-Form McGill Pain Questionnaire 2 (SF-MPQ2) score immediately before and immediately after intervention.

RESULTS

We enrolled 22 adults (age: 59.8 ± 12.1 years) with intractable neuropathic pain. Linear-effects models showed significant effects of the stimulation condition on changes in VAS pain intensity (p = 0.03) and SF-MPQ2 (p = 0.01). Tukey multiple comparison tests revealed that 10-Hz rTMS with 2000 pulses provided better pain relief than sham stimulation, with greater decreases in VAS pain intensity (p = 0.03) and SF-MPQ2 (p = 0.02).

CONCLUSIONS

The results of this study suggest that high-dose stimulation (specifically, 10-Hz rTMS at 2000 pulses) is more effective than lower-dose stimulation for treating neuropathic pain.

A Randomized, Sham-Controlled Trial of Repetitive Transcranial Magnetic Stimulation Targeting M1 and S2 in Central Poststroke Pain: A Pilot Trial

OBJECTIVES

Central poststroke pain (CPSP), a neuropathic pain condition, is difficult to treat. Repetitive transcranial magnetic stimulation (rTMS) targeted to the primary motor cortex (M1) can alleviate the condition, but not all patients respond. We aimed to assess a promising alternative rTMS target, the secondary somatosensory cortex (S2), for CPSP treatment.

MATERIALS AND METHODS

This prospective, randomized, double-blind, sham-controlled three-arm crossover trial assessed navigated rTMS (nrTMS) targeted to M1 and S2 (10 sessions, 5050 pulses per session at 10 Hz). Participants were evaluated for pain, depression, anxiety, health-related quality of life, upper limb function, and three plasticity-related gene polymorphisms including Dopamine D2 Receptor (DRD2). We monitored pain intensity and interference before and during stimulations and at one month. A conditioned pain modulation test was performed using the cold pressor test. This assessed the efficacy of the descending inhibitory system, which may transmit TMS effects in pain control.

RESULTS

We prescreened 73 patients, screened 29, and included 21, of whom 17 completed the trial. NrTMS targeted to S2 resulted in long-term (from baseline to one-month follow-up) pain intensity reduction of ≥30% in 18% (3/17) of participants. All stimulations showed a short-term effect on pain (17-20% pain relief), with no difference between M1, S2, or sham stimulations, indicating a strong placebo effect. Only nrTMS targeted to S2 resulted in a significant long-term pain intensity reduction (15% pain relief). The cold pressor test reduced CPSP pain intensity significantly (p = 0.001), indicating functioning descending inhibitory controls. The homozygous DRD2 T/T genotype is associated with the M1 stimulation response.

CONCLUSIONS

S2 is a promising nrTMS target in the treatment of CPSP. The DRD2 T/T genotype might be a biomarker for M1 nrTMS response, but this needs confirmation from a larger study.

Effects of Repetitive Transcranial Magnetic Stimulation on the Primary Motor Cortex of Individuals with Fibromyalgia: A Systematic Review and Meta-Analysis

The purpose of this study was to quantify the effect of repetitive transcranial magnetic stimulation (rTMS), which is recommended for the improvement of some pain-related symptoms and for antidepressant treatment, on the primary motor cortex (M1) in patients with fibromyalgia (FM). We searched for studies comparing rTMS and sham rTMS in the M1 of FM patients. Pain intensity, quality of life, health status, and depression were compared with or without rTMS for at least 10 sessions. We searched four databases. Quality assessment and quantitative analysis were performed using RevMan 5.4. After screening, five randomized controlled trials of 170 patients with FM were included in the analysis. As a result of the meta-analysis of rTMS on the M1 of individuals with FM, high-frequency rTMS resulted in a significant improvement on quality of life (MD = -2.50; 95% CI: -3.99 to -1.01) compared with sham rTMS. On the other hand, low-frequency rTMS resulted in a significant improvement on health status (MD = 15.02; 95% CI: 5.59 to 24.45). The application of rTMS to the M1 is proposed as an adjunctive measure in the treatment of individuals with FM. Because rTMS has various effects depending on each application site, it is necessary to classify sites or set frequencies as variables.

Transcranial Magnetic Stimulation for the Neurological Patient: Scientific Principles and Applications

Non-invasive brain stimulation has been increasingly recognized for its potential as an investigational, diagnostic and therapeutic tool across the clinical neurosciences. Transcranial magnetic stimulation (TMS) is a non-invasive method of focal neuromodulation. Diagnostically, TMS can be used to probe cortical excitability and plasticity, as well as for functional mapping. Therapeutically, depending on the pattern employed, TMS can either facilitate or inhibit stimulated cortex potentially modulating maladaptive physiology through its effects on neuroplasticity. Despite this potential, applications of TMS in neurology have only been approved for diagnostic clinical neurophysiology, pre-surgical mapping of motor and language cortex, and the treatment of migraines. In this article, we discuss the principles of TMS and its clinical applications in neurology, including experimental applications in stroke rehabilitation, seizures, autism spectrum disorder, neurodegenerative disorders, movement disorders, tinnitus, chronic pain and functional neurological disorder. To promote increased cross-talk across neurology and psychiatry, we also succinctly review the TMS literature for the treatment of major depression and obsessive compulsive disorder. Overall, we argue that larger clinical trials that are better informed by circuit-level biomarkers and pathophysiological models will lead to an expansion of the application of TMS for patients cared for by neurologists.

Efficacy and tolerability in patients with chronic facial pain of two consecutive treatment periods of rTMS applied over the facial motor cortex, using protocols differing in stimulation frequency, duration, and train pattern

OBJECTIVE

We conducted an open-label cross-over study assessing the global effect of two high-frequency protocols of electric-field navigated repetitive transcranial magnetic stimulation (rTMS) targeted to functional facial motor cortex and comparing their efficacy and tolerability in patients with chronic facial pain. Outcome predictors were also assessed.

METHODS

We randomized twenty consecutive patients with chronic facial pain (post-traumatic trigeminal neuropathic pain, n=14; persistent idiopathic facial pain, n=4; secondary trigeminal neuralgia, n=2) to receive two distinct 5-day rTMS interventions (10Hz, 2400 pulses and 20Hz, 3600 pulses) separated by six weeks. The target area was assessed by mapping of lower face representation. The primary endpoint was the change in weekly mean of pain intensity (numeric rating scale, NRS) between the baseline and therapy week (1^st week), and follow-up weeks (2^nd and 3^rd weeks) for each rTMS intervention. Response was defined using a combination scale including the patient's global impression of change and continuance with maintenance treatment.

RESULTS

Overall, pain intensity NRS decreased from 7.4 at baseline to 5.9 ten weeks later, after the second rTMS intervention (p=0.009). The repetition of the treatment had a significant effect (F=4.983, p=0.043) indicating that the NRS scores are lower during the second four weeks period. Eight (40%) patients were responders, 4 (20%) exhibited a modest effect, 4 (20%) displayed no effect, and 4 (20%) experienced worsening of pain. High disability and high pain intensity (>7) predicted a better outcome (p=0.043 and p=0.045). Female gender, shorter duration of pain and low Beck Anxiety Inventory scores showed a trend towards a better outcome (p=0.052, 0.060 and 0.055, respectively).

CONCLUSIONS

High-frequency rTMS targeted to face M1 alleviates treatment resistant chronic facial pain. Repeated treatment improves the analgesic effect. A protocol with higher frequency (above 10Hz), longer session duration (more than 20 minutes) and higher number of pulses (above 2400 pulses/session) did not improve the outcome. The results support early consideration of rTMS.

Evidence Mapping Based on Systematic Reviews of Repetitive Transcranial Magnetic Stimulation on the Motor Cortex for Neuropathic Pain

BACKGROUND AND OBJECTIVE

There is vast published literature proposing repetitive transcranial magnetic stimulation (rTMS) technology on the motor cortex (M1) for the treatment of neuropathic pain (NP). Systematic reviews (SRs) focus on a specific problem and do not provide a comprehensive overview of a research area. This study aimed to summarize and analyze the evidence of rTMS on the M1 for NP treatment through a new synthesis method called evidence mapping.

METHODS

Searches were conducted in PubMed, EMBASE, Epistemonikos, and The Cochrane Library to identify the studies that summarized the effectiveness of rTMS for NP. The study type was restricted to SRs with or without meta-analysis. All literature published before January 23, 2021, was included. Two reviewers independently screened the literature, assessed the methodological quality, and extracted the data. The methodological quality of the included SRs was assessed by using the A Measurement Tool to Assess Systematic Reviews (AMSTAR-2). Data were extracted following a defined population, intervention, comparison, and outcome (PICO) framework from primary studies that included SRs. The same PICO was categorized into PICOs according to interventions [frequency, number of sessions (short: 1-5 sessions, medium: 5-10 sessions, and long: >10 sessions)] and compared. The evidence map was presented in tables and a bubble plot.

RESULTS

A total of 38 SRs met the eligibility criteria. After duplicate primary studies were removed, these reviews included 70 primary studies that met the scope of evidence mapping. According to the AMSTAR-2 assessment, the quality of the included SRs was critically low. Of these studies, 34 SRs scored "critically low" in terms of methodological quality, 2 SR scored "low," 1 SR scored "moderate," and 1 SR scored "high."

CONCLUSION

Evidence mapping is a useful methodology to provide a comprehensive and reliable overview of studies on rTMS for NP. Evidence mapping also shows that further investigations are necessary to highlight the optimal stimulation protocols and standardize all parameters to fill the evidence gaps of rTMS. Given that the methodological quality of most included SRs was "critically low," further investigations are advised to improve the methodological quality and the reporting process of SRs.

Prolonged Continuous Theta Burst Stimulation to Demonstrate a Larger Analgesia as Well as Cortical Excitability Changes Dependent on the Context of a Pain Episode

A series of neuropathic pain conditions have a prevalence in older adults potentially associated with declined functioning of the peripheral and/or central nervous system. Neuropathic pain conditions demonstrate defective cortical excitability and intermissions, which raises questions of the impact of pain on cortical excitability changes and when to deliver repetitive transcranial magnetic stimulation (rTMS) to maximize the analgesic effects. Using prolonged continuous theta-burst stimulation (pcTBS), a relatively new rTMS protocol to increase excitability, this study was designed to investigate pcTBS analgesia and cortical excitability in the context of pain. With capsaicin application, twenty-nine healthy participants received pcTBS or Sham stimulation either in the phase of pain initialization (capsaicin applied) or pain ascending (20 min after capsaicin application). Pain intensity was measured with a visual-analogic scale (VAS). Cortical excitability was assessed by motor-evoked potential (MEP) and cortical silent period (CSP) which evaluates corticospinal excitability and GABAergic intracortical inhibition, respectively. Our data on pain dynamics demonstrated that pcTBS produced a consistent analgesic effect regardless of the time frame of pcTBS. More importantly, pcTBS delivered at pain initialization induced a larger pain reduction and a higher response rate compared to the stimulation during pain ascending. We further provide novel findings indicating distinct mechanisms of pcTBS analgesia dependent on the context of pain, in which pcTBS delivered at pain initialization was able to reverse depressed MEP, whereby pcTBS during pain ascending was associated with increased CSP. Overall, our data indicate pcTBS to be a potential protocol in pain management that could be delivered before the initialization of a pain episode to improve rTMS analgesia, potentially through inducing early corticospinal excitability changes that would be suppressed by nociceptive transmission.

Effects of rTMS and tDCS on neuropathic pain after brachial plexus injury: a randomized placebo-controlled pilot study

Neuropathic pain after brachial plexus injury (NPBPI) is a highly disabling clinical condition and is increasingly prevalent due to increased motorcycle accidents. Currently, no randomized controlled trials have evaluated the effectiveness of non-invasive brain stimulation techniques such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct-current stimulation (tDCS) in patients suffering from NPBPI. In this study, we directly compare the efficacy of 10-Hz rTMS and anodal 2 mA tDCS techniques applied over the motor cortex (5 daily consecutive sessions) in 20 patients with NPBPI, allocated into 2 parallel groups (active or sham). The order of the sessions was randomised for each of these treatment groups according to a crossover design and separated by a 30-day interval. Scores for "continuous" and "paroxysmal" pain (primary outcome) were tabulated after the last stimulation day and 30 days after. Secondary outcomes included the improvement in multidimensional aspects of pain, anxiety state and quality of life from a qualitative and quantitative approach. Active rTMS and tDCS were both superior to sham in reducing continuous (p < 0.001) and paroxysmal (p = 0.002; p = 0.02) pain as well as in multidimensional aspects of pain (p = 0.001; p = 0.002) and anxiety state (p =  < 0.001; p = 0.005). Our results suggest rTMS and tDCS are able to treat NPBPI with little distinction in pain and anxiety state, which may promote the use of tDCS in brachial plexus injury pain management, as it constitutes an easier and more available technique.Clinical Trial Registration: http://www.ensaiosclinicos.gov.br/, RBR-5xnjbc - Sep 3, 2018.

Difference in Analgesic Effects of Repetitive Transcranial Magnetic Stimulation According to the Site of Pain

High-frequency repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex for neuropathic pain has been shown to be effective, according to systematic reviews and therapeutic guidelines. However, our large, rigorous, investigator-initiated, registration-directed clinical trial failed to show a positive primary outcome, and its subgroup analysis suggested that the analgesic effect varied according to the site of pain. The aim of this study was to investigate the differences in analgesic effects of rTMS for neuropathic pain between different pain sites by reviewing our previous clinical trials. We included three clinical trials in this mini meta-analysis: a multicenter randomized controlled trial at seven hospitals (N = 64), an investigator-initiated registration-directed clinical trial at three hospitals (N = 142), and an exploratory clinical trial examining different stimulation parameters (N = 22). The primary efficacy endpoint (change in pain scale) was extracted for each patient group with pain in the face, upper limb, or lower limb, and a meta-analysis of the efficacy of active rTMS against sham stimulation was performed. Standardized mean difference (SMD) with 95% confidence interval (CI) was calculated for pain change using a random-effects model. The analgesic effect of rTMS for upper limb pain was favorable (SMD = -0.45, 95% CI: -0.77 to -0.13). In contrast, rTMS did not produce significant pain relief on lower limb pain (SMD = 0.04, 95% CI: -0.33 to 0.41) or face (SMD = -0.24, 95% CI: -1.59 to 1.12). In conclusion, these findings suggest that rTMS provides analgesic effects in patients with neuropathic pain in the upper limb, but not in the lower limb or face, under the conditions of previous clinical trials. Owing to the main limitation of small number of studies included, many aspects should be clarified by further research and high-quality studies in these patients.

Effects of repetitive transcranial magnetic stimulation on neuropathic pain: A systematic review and meta-analysis

Neuropathic pain (NP) is a chronic pain condition caused by lesion or disease of the somatosensory nervous system. Repetitive transcranial magnetic stimulation (rTMS) is a neuroregulatory tool that uses pulsed magnetic fields to modulate the cerebral cortex. This review aimed to ascertain the therapeutic effect of rTMS on NP and potential factors regulating the therapeutic effect of rTMS. Database search included Web of Science, Embase, Pubmed, and Cochrane Library from inception to July 2021. Eligible studies included randomized controlled studies of the analgesic effects of rTMS in patients with NP. Thirty-eight studies were included. Random effect analysis showed effect sizes of -0.66 (95 % CI, -0.87 to -0.46), indicating that real rTMS was better than sham condition in reducing pain (P < 0.001). This comprehensive review indicated that stimulation frequency, intervention site, and location of lesion were important factors affecting the therapeutic effect. The findings of this study may guide clinical decisions and future research.

The Japan Neurosurgical Database: Statistics Update 2018 and 2019

Each year, the Japan Neurosurgical Society (JNS) reports up-to-date statistics from the Japan Neurosurgical Database regarding case volume, patient demographics, and in-hospital outcomes of the overall cohort and neurosurgical subgroup according to the major classifications of main diagnosis. We hereby report patient demographics, in-hospital mortality, length of hospital stay, purpose of admission, number of medical management, direct surgery, endovascular treatment, and radiosurgery of the patients based on the major classifications and/or main diagnosis registered in 2018 and 2019 in the overall cohort (523283 and 571143 patients, respectively) and neurosurgical subgroup (177184 and 191595 patients, respectively). The patient demographics, disease severity, proportion of purpose of admission (e.g., operation, 33.9-33.5%) and emergent admission (68.4-67.8%), and in-hospital mortality (e.g., cerebrovascular diseases, 6.3-6.5%; brain tumor, 3.1-3%; and neurotrauma, 4.3%) in the overall cohort were comparable between 2018 and 2019. In total, 207783 and 225217 neurosurgical procedures were performed in the neurosurgical subgroup in 2018 and 2019, respectively, of which endovascular treatment comprised 19.1% and 20.3%, respectively. Neurosurgical management of chronic subdural hematoma (19.4-18.9%) and cerebral aneurysm (15.4-14.8%) was most common. Notably, the proportion of management of ischemic stroke/transient ischemic attack, including recombinant tissue plasminogen activator infusion and endovascular acute reperfusion therapy, increased from 7.5% in 2018 to 8.8% in 2019. The JNS statistical update represents a critical resource for the lay public, policy makers, media professionals, neurosurgeons, healthcare administrators, researchers, health advocates, and others seeking the best available data on neurosurgical practice.

Exploratory study of optimal parameters of repetitive transcranial magnetic stimulation for neuropathic pain in the lower extremities

Introduction

Pain relief from repetitive transcranial magnetic stimulation (rTMS) over the primary motor cortex (M1) is particularly poor in patients with leg pain. The optimal parameters for relieving leg pain remain poorly understood. The purpose of this study was to explore the optimal stimulation parameters of M1-rTMS for patients with leg pain.

Methods

Eleven patients with neuropathic pain in the leg randomly underwent 6 conditions of M1-rTMS with different stimulation intensities, sites, and coil directions, including sham stimulation. The 5 active conditions were as follows: 90% or 110% of the resting motor threshold (RMT) on the M1 hand with an anteroposterior coil direction, 90% or 110% RMT on the M1 foot in the anteroposterior direction, and 90% RMT on the M1 foot in the mediolateral direction. Each condition was administered for 3 days. Pain intensity was evaluated using the Visual Analogue Scale and Short-Form McGill Pain Questionnaire 2 at baseline and up to 7 days after each intervention.

Results

Visual Analogue Scale scores were significantly reduced after the following active rTMS conditions: 90% RMT on the M1 hand, 90% RMT on the M1 foot with any coil direction, and 110% RMT on the M1 foot. The Short-Form McGill Pain Questionnaire 2 results were similar to those obtained using the Visual Analogue Scale. The analgesic effect of rTMS with stimulus intensity above the RMT was not superior to that below the RMT.

Conclusion

We suggest that the optimal stimulation parameters of rTMS for patients with neuropathic pain in the leg may target the M1 foot or M1 hand with an intensity below the RMT.

Repetitive transcranial magnetic stimulation for neuropathic pain: a randomized multicentre sham-controlled trial

Repetitive transcranial magnetic stimulation (rTMS) has been proposed to treat neuropathic pain but the quality of evidence remains low. We aimed to assess the efficacy and safety of neuronavigated rTMS to the motor cortex (M1) or dorsolateral prefrontal cortex (DLPFC) in neuropathic pain over 25 weeks. We did a randomised double-blind, placebo-controlled trial at four outpatient clinics in France. Patients aged 18-75 years with peripheral neuropathic pain were randomly assigned in a 1:1 ratio to M1 or DLPFC-rTMS and re-randomised in a 2:1 ratio to active or sham rTMS (10 Hz, 3000 pulses/session, 15 sessions over 22 weeks). Patients and investigators were blind to treatment allocation. The primary endpoint was the comparison between active M1-rTMS, active DLPCF-rTMS and sham-rTMS for the change over the course of 25 weeks (group by time interaction) in average pain intensity (from 0 no pain to 10 maximal pain) on the Brief Pain Inventory (BPI), using a mixed model repeated measures analysis in patients who received at least one rTMS session (modified ITT population). Secondary outcomes included other measures of pain intensity and relief, sensory and affective dimensions of pain, quality of pain, self reported pain intensity and fatigue (patients diary), patient and clinician global impression of change (PGIC, CGIC), quality of life, sleep, mood and catastrophizing. This study is registered with ClinicalTrials.gov NCT02010281. A total of 152 patients were randomised and 149 received treatment (49 for M1; 52 for DLPFC; 48 for sham). M1-rTMS reduced pain intensity versus sham-rTMS (estimate for group x session interaction: -0.048 ± 0.02; 95% CI: -0.09 to -0.01; p = 0.01). DLPFC-rTMS was not better than sham (estimate: -0.003 ± 0.01; 95% CI:-0.04 to 0.03, p = 0.9). M1-rRMS, but not DLPFC-rTMS, was also superior to sham-rTMS on pain relief, sensory dimenson of pain, self reported pain intensity and fatigue, PGIC and CGIC. There were no effect on quality of pain, mood, sleep and quality of life as all groups improved similarly over time. Headache was the most common side effect and occurred in 17 (34.7%), 23 (44.2%) and 13 (27.1%) patients from M1, DLPFC and sham groups respectively (p = 0.2). Our results support the clinical relevance of M1-rTMS, but not of DLPFC-rTMS, for peripheral neuropathic pain with an excellent safety profile.

Atlas-informed computational processing pipeline for individual targeting of brain areas for therapeutic navigated transcranial magnetic stimulation

OBJECTIVE

Navigated transcranial magnetic stimulation (nTMS) is targeted at different cortical sites for diagnostic, therapeutic, and neuroscientific purposes. Correct identification of the cortical target areas is important for achieving desired effects, but it is challenging when no direct responses arise upon target area stimulation. We aimed at utilizing atlas-based marking of cortical areas for nTMS targeting to present a convenient, rater-independent method for overlaying the individual target sites with brain anatomy.

METHODS

We developed a pipeline, which fits a brain atlas to the individual brain and enables visualization of the target areas during the nTMS session. We applied the pipeline to our previous nTMS data, focusing on depression and schizophrenia patients. Furthermore, we included examples of Tourette syndrome and tinnitus therapies, as well as neurosurgical and motor mappings.

RESULTS

In depression and schizophrenia patients, the visually selected dorsolateral prefrontal cortex (DLPFC) targets were close to the border between atlas areas A9/46 and A8. In the other areas, the atlas-based areas were in agreement with the treatment targets.

CONCLUSIONS

The atlas-based target areas agreed well with the cortical targets selected by experts during the treatments.

SIGNIFICANCE

Overlaying atlas information over the navigation view is a convenient and useful add-on for improving nTMS targeting.

Analgesic Effect of Noninvasive Brain Stimulation for Neuropathic Pain Patients: A Systematic Review

Introduction

The objective of this review is to systematically summarize the consensus on best practices for different NP conditions of the two most commonly utilized noninvasive brain stimulation (NIBS) technologies, repetitive transcranial magnetic stimulation (rTMS), and transcranial direct current stimulation (tDCS).

Methods

PubMed was searched according to the predetermined keywords and criteria. Only English language studies and studies published up to January 31, 2020 were taken into consideration. Meta-analyses, reviews, and systematic reviews were excluded first, and those related to animal studies or involving healthy volunteers were also excluded. Finally, 29 studies covering 826 NP patients were reviewed.

Results

The results from the 24 enrolled studies and 736 NP patients indicate that rTMS successfully relieved the pain symptoms of 715 (97.1%) NP patients. Also, five studies involving 95 NP patients (81.4%) also showed that tDCS successfully relieved NP. In the included studied, the M1 region plays a key role in the analgesic treatment of NIBS. The motor evoked potentials (MEPs), the 10–20 electroencephalography system (EEG 10/20 system), and neuro-navigation methods are used in clinical practice to locate therapeutic targets. Based on the results of the review, the stimulation parameters of rTMS that best induce an analgesic effect are a stimulation frequency of 10–20 Hz, a stimulation intensity of 80–120% of RMT, 1000–2000 pulses, and 5–10 sessions, and the most effective parameters of tDCS are a current intensity of 2 mA, a session duration of 20–30 min, and 5–10 sessions.

Conclusions

Our systematically reviewed the evidence for positive and negative responses to rTMS and tDCS for NP patient care and underscores the analgesic efficacy of NIBS in patients with NP. The treatment of NP should allow the design of optimal treatments for individual patients.

Repetitive transcranial magnetic stimulation restores altered functional connectivity of central poststroke pain model monkeys

Central poststroke pain (CPSP) develops after a stroke around the somatosensory pathway. CPSP is hypothesized to be caused by maladaptive reorganization between various brain regions. The treatment for CPSP has not been established; however, repetitive transcranial magnetic stimulation (rTMS) to the primary motor cortex has a clinical effect. To verify the functional reorganization hypothesis for CPSP development and rTMS therapeutic mechanism, we longitudinally pursued the structural and functional changes of the brain by using two male CPSP model monkeys (Macaca fuscata) developed by unilateral hemorrhage in the ventral posterolateral nucleus of the thalamus. Application of rTMS to the ipsilesional primary motor cortex relieved the induced pain of the model monkeys. A tractography analysis revealed a decrease in the structural connectivity in the ipsilesional thalamocortical tract, and rTMS had no effect on the structural connectivity. A region of interest analysis using resting-state functional magnetic resonance imaging revealed inappropriately strengthened functional connectivity between the ipsilesional mediodorsal nucleus of the thalamus and the amygdala, which are regions associated with emotion and memory, suggesting that this may be the cause of CPSP development. Moreover, rTMS normalizes this strengthened connectivity, which may be a possible therapeutic mechanism of rTMS for CPSP.

A randomized controlled trial of 5 daily sessions and continuous trial of 4 weekly sessions of repetitive transcranial magnetic stimulation for neuropathic pain

Supplemental Digital Content is Available in the Text.

Five daily sessions of repetitive transcranial magnetic stimulation with stimulus conditions were ineffective in neuropathic pain relief. Long-term administration should be investigated for clinical use of repetitive transcranial magnetic stimulation in neuropathic pain.

We conducted a multicenter, randomized, patient- and assessor-blinded, sham-controlled trial to investigate the efficacy of repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex (M1) in patients with neuropathic pain (NP). Patients were randomly assigned to receive 5 daily sessions of active or sham rTMS of M1 corresponding to the part of the body experiencing the worst pain (500 pulses per session at 5 Hz). Responders were invited to enroll in an open-label continuous trial involving 4 weekly sessions of active rTMS. The primary outcome was a mean decrease in a visual analogue scale of pain intensity (scaled 0-100 mm) measured daily during the daily sessions in an intention-to-treat population. Secondary outcomes were other pain scores, quality-of-life measures, and depression score. One hundred forty-four patients were assigned to the active or sham stimulation groups. The primary outcome, mean visual analogue scale decreases, was not significantly different (P = 0.58) between the active stimulation group (mean, 8.0) and the sham group (9.2) during the daily sessions. The secondary outcomes were not significantly different between 2 groups. The patients enrolled in the continuous weekly rTMS achieved more pain relief in the active stimulation group compared with the sham (P < 0.01). No serious adverse events were observed. Five daily sessions of rTMS with stimulus conditions used in this trial were ineffective in short-term pain relief in the whole study population with various NP. Long-term administration to the responders should be investigated for the clinical use of rTMS on NP in the future trials.

Nonpharmacological therapies for central poststroke pain: A systematic review

BACKGROUND

Central poststroke pain (CPSP) is a neuropathic pain syndrome that can occur after a cerebrovascular accident. It has negative effects on mood, sleep, rehabilitation, and quality of life in stroke patients. This systematic review assessed the efficacy and safety of nonpharmacological therapies for treating CPSP.

METHODS

The Cochrane, PubMed, Embase, and Web of Science databases were systematically searched for studies from inception to August 2020. Two authors worked independently and in duplicate to identify suitable studies.

RESULTS

Eleven studies were identified. Pain related to CPSP was ameliorated by precentral gyrus stimulation (P = .01), caloric vestibular stimulation (P = 0.004), transcranial direct current stimulation (P < .05), and bee venom acupuncture point injection (P = .009). Acupuncture (P = .72) and electroacupuncture therapies (P > .05) were as effective for thalamic pain as oral carbamazepine treatment. Motor cortex stimulation, but not deep brain stimulation (DBS), was effective for treating refractory CPSP, and appeared to be more effective than thalamic stimulation for controlling bulbar pain secondary to Wallenberg syndrome. However, DBS in the ventral striatum or anterior limb of the internal capsule improved depression (P = .020) and anxiety in patients with refractory CPSP. Some serious adverse events were reported in response to invasive electrical brain stimulation, but most of these effects recovered with treatment.

CONCLUSIONS

Nonpharmacological therapies appear to be effective in CPSP, but the evidence is relatively weak. Invasive electrical brain stimulation can be accompanied by serious adverse events, but most patients recover from these effects.

Repetitive transcranial magnetic stimulation of the primary motor cortex in management of chronic neuropathic pain: a systematic review

OBJECTIVES

Repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex (M1) with frequencies 5-20 Hz is an expanding non-invasive treatment for chronic neuropathic pain (NP). Outcome data, however, show considerable inhomogeneity with concern to the levels of effect due to the great diversity of treated conditions. The aim of this review was to survey the literature regarding the efficacy and safety of M1 rTMS, and the accuracy to predict a positive response to epidural motor cortex stimulation (MCS) which is supposed to give a more longstanding pain relief.

METHODS

A systematic literature search was conducted up to June 2019 in accordance with the PRISMA guidelines. We used the PICO Model to define two specific clinical questions: (1) Does rTMS of M1 relieve NP better than sham treatment? (2) Can the response to rTMS be used to predict the effect of epidural MCS? After article selection, data extraction, and study quality assessment, the certainty of evidence of treatment effect was defined using the GRADE system.

RESULTS

Data on 5-20 Hz (high-frequency) rTMS vs. sham was extracted from 24 blinded randomised controlled trials which were of varying quality, investigated highly heterogeneous pain conditions, and used excessively variable stimulation parameters. The difference in pain relief between active and sham stimulation was statistically significant in 9 of 11 studies using single-session rTMS, and in 9 of 13 studies using multiple sessions. Baseline data could be extracted from 6 single and 12 multiple session trials with a weighted mean pain reduction induced by active rTMS, compared to baseline, of -19% for single sessions, -32% for multiple sessions with follow-up <30 days, and -24% for multiple sessions with follow-up ≥30 days after the last stimulation session. For single sessions the weighted mean difference in pain reduction between active rTMS and sham was 15 percentage points, for multiple sessions the difference was 22 percentage points for follow-ups <30 days, and 15 percentage points for follow-ups ≥30 days. Four studies reported data that could be used to evaluate the accuracy of rTMS to predict response to MCS, showing a specificity of 60-100%, and a positive predictive value of 75-100%. No serious adverse events were reported.

CONCLUSIONS

rTMS targeting M1 can result in significant reduction of chronic NP which, however, is transient and shows a great heterogeneity between studies; very low certainty of evidence for single sessions and low for multiple sessions. Multiple sessions of rTMS can maintain a more longstanding effect. rTMS seems to be a fairly good predictor of a positive response to epidural MCS and may be used to select patients for implantation of permanent epidural electrodes. More studies are needed to manifest the use of rTMS for this purpose. Pain relief outcomes in a longer perspective, and outcome variables other than pain reduction need to be addressed more consistently in future studies to consolidate the applicability of rTMS in routine clinical practice.

Repetitive Transcranial Magnetic Stimulation for Dysesthesia Caused by Subacute Myelo-Optico-Neuropathy: A Case Report

Subacute myelo-optico-neuropathy (SMON) is caused by the ingestion of clioquinol (5-chloro-7-iodo-8-hydroxyquinoline), which is an intestinal antibacterial drug. Patients with SMON typically suffer from abnormal dysesthesia in the lower limbs, which cannot explain the mechanism only in pathology and electrophysiology. Neuromodulation therapies are increasingly being investigated as a means of alleviating abnormal sensory disturbances. We report here the response to repetitive transcranial magnetic stimulation (rTMS) for dysesthesia in a patient with SMON. The patient underwent rTMS treatment once per week for 12 weeks. rTMS was administered at 10 Hz, 90% of the resting motor threshold over the bilateral primary motor cortex foot area, for a total of 1,500 stimuli per day. After the treatment had finished at 12 weeks, the abnormal dysesthesia gradually declined. At first, there were improvements only in the area with a feeling of adherence. Later, this sensation was eliminated. Three months following the application, most of the feeling of adherence had disappeared and the feeling of tightness was slightly reduced. In contrast, the throbbing feeling had not changed during this period. Dysesthesia may indicate a process of central sensitization, which would contribute to chronic neuromuscular dysfunction. This case suggests that rTMS is a promising therapeutic application for dysesthesia.

Pharmacological and non-pharmacological treatments for neuropathic pain: Systematic review and French recommendations

Neuropathic pain remains a significant unmet medical need. Several recommendations have recently been proposed concerning pharmacotherapy, neurostimulation techniques and interventional management, but no comprehensive guideline encompassing all these treatments has yet been issued. We performed a systematic review of pharmacotherapy, neurostimulation, surgery, psychotherapies and other types of therapy for peripheral or central neuropathic pain, based on studies published in peer-reviewed journals before January 2018. The main inclusion criteria were chronic neuropathic pain for at least three months, a randomized controlled methodology, at least three weeks of follow-up, at least 10 patients per group, and a double-blind design for drug therapy. Based on the GRADE system, we provide weak-to-strong recommendations for use and proposal as a first-line treatment for SNRIs (duloxetine and venlafaxine), gabapentin and tricyclic antidepressants and, for topical lidocaine and transcutaneous electrical nerve stimulation specifically for peripheral neuropathic pain; a weak recommendation for use and proposal as a second-line treatment for pregabalin, tramadol, combination therapy (antidepressant combined with gabapentinoids), and for high-concentration capsaicin patches and botulinum toxin A specifically for peripheral neuropathic pain; a weak recommendation for use and proposal as a third-line treatment for high-frequency rTMS of the motor cortex, spinal cord stimulation (failed back surgery syndrome and painful diabetic polyneuropathy) and strong opioids (in the absence of an alternative). Psychotherapy (cognitive behavioral therapy and mindfulness) is recommended as a second-line therapy, as an add-on to other therapies. An algorithm encompassing all the recommended treatments is proposed.

Transcranial Magnetic Stimulation for Pain, Headache, and Comorbid Depression: INS-NANS Expert Consensus Panel Review and Recommendation

BACKGROUND

While transcranial magnetic stimulation (TMS) has been studied for the treatment of psychiatric disorders, emerging evidence supports its use for pain and headache by stimulating either motor cortex (M1) or dorsolateral prefrontal cortex (DLPFC). However, its clinical implementation is hindered due to a lack of consensus in the quality of clinical evidence and treatment recommendation/guideline(s). Thus, working collaboratively, this multinational multidisciplinary expert panel aims to: 1) assess and rate the existing outcome evidence of TMS in various pain/headache conditions; 2) provide TMS treatment recommendation/guidelines for the evaluated conditions and comorbid depression; and 3) assess the cost-effectiveness and technical issues relevant to the long-term clinical implementation of TMS for pain and headache.

METHODS

Seven task groups were formed under the guidance of a 5-member steering committee with four task groups assessing the utilization of TMS in the treatment of Neuropathic Pain (NP), Acute Pain, Primary Headache Disorders, and Posttraumatic Brain Injury related Headaches (PTBI-HA), and remaining three assessing the treatment for both pain and comorbid depression, and the cost-effectiveness and technological issues relevant to the treatment.

RESULTS

The panel rated the overall level of evidence and recommendability for clinical implementation of TMS as: 1) high and extremely/strongly for both NP and PTBI-HA respectively; 2) moderate for postoperative pain and migraine prevention, and recommendable for migraine prevention. While the use of TMS for treating both pain and depression in one setting is clinically and financially sound, more studies are required to fully assess the long-term benefit of the treatment for the two highly comorbid conditions, especially with neuronavigation.

CONCLUSIONS

After extensive literature review, the panel provided recommendations and treatment guidelines for TMS in managing neuropathic pain and headaches. In addition, the panel also recommended more outcome and cost-effectiveness studies to assess the feasibility of the long-term clinical implementation of the treatment.

Trends of Repetitive Transcranial Magnetic Stimulation From 2009 to 2018: A Bibliometric Analysis

Repetitive transcranial magnetic stimulation (rTMS) technology, which is amongst the most used non-invasive brain stimulation techniques currently available, has developed rapidly from 2009 to 2018. However, reports on the trends of rTMS using bibliometric analysis are rare. The goal of the present bibliometric analysis is to analyze and visualize the trends of rTMS, including general (publication patterns) and emerging trends (research frontiers), over the last 10 years by using the visual analytic tool CiteSpace V. Publications related to rTMS from 2009 to 2018 were retrieved from the Web of Science (WoS) database, including 2,986 peer-reviewed articles/reviews. Active authors, journals, institutions, and countries were identified by WoS and visualized by CiteSpace V, which could also detect burst changes to identify emerging trends. GraphPad Prism 8 was used to analyze the time trend of annual publication outputs. The USA ranked first in this field. Pascual-Leone A (author A), Fitzgerald PB (author B), George MS (author C), Lefaucheur JP (author D), and Fregni F (author E) made great contributions to this field of study. The most prolific institution to publish rTMS-related publications in the last decade was the University of Toronto. The journal Brain Stimulation published most papers. Lefaucheur et al.'s paper in 2014, and the keyword "sham controlled trial" showed the strongest citation bursts by the end of 2018, which indicates increased attention to the underlying work, thereby indicating the research frontiers. This study reveals the publication patterns and emerging trends of rTMS based on the records published from 2009 to 2018. The insights obtained have reference values for the future research and application of rTMS.

Pilot study of repetitive transcranial magnetic stimulation in patients with chemotherapy-induced peripheral neuropathy

OBJECTIVE

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the intractable long-term side effects of anticancer medications and results in pain and dysesthesia. Repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex has been demonstrated to provide effective relief for intractable neuropathic pain. The objective of this study was to investigate the effects of rTMS treatment on CIPN in cancer patients.

MATERIALS AND METHODS

Eleven female patients with breast cancer or gynecologic cancer (mean age 64.8 [standard deviation 7.8]) who had neuropathic pain and/or peripheral sensory neuropathy, with a minimum two grade severity based on the scale of the National Cancer Institutes' Common Terminology Criteria for Adverse Events (version 4.0) were enrolled. Patients received rTMS (5-Hz; 500 pulses/session; figure-8 coil) on their primary motor cortex corresponding to the target extremity. The intensity of pain and dysesthesia for all extremities was evaluated using a visual analog scale for pain, dysesthesia, and the Japanese version of the short-form McGill Pain Questionnaire 2 (SFMPQ2).

RESULTS

rTMS for target extremity significantly decreased the visual analog scale of pain and dysesthesia. The intensity of pain measured by the SFMPQ2 was also decreased in the target extremity. Regarding non-target extremities, only dysesthesia significantly decreased as a result of rTMS. No adverse events were observed.

CONCLUSION

This is an initial report demonstrating the potential of rTMS for the treatment of CIPN. We suggest rTMS could be potentially beneficial and effective as a treatment for pain and dysesthesia in patients with CIPN.

Effect of Repetitive Transcranial Magnetic Stimulation on Pain Management: A Systematic Narrative Review

Recently, clinicians have been using repetitive transcranial magnetic stimulation (rTMS) for treating various pain conditions. This systematic narrative review aimed to examine the use and efficacy of rTMS for controlling various pain conditions. A PubMed search was conducted for articles that were published until June 7, 2019 and used rTMS for pain alleviation. The key search phrase for identifying potentially relevant articles was (repetitive transcranial magnetic stimulation AND pain). The following inclusion criteria were applied for article selection: (1) patients with pain, (2) rTMS was applied for pain management, and (3) follow-up evaluations were performed after rTMS stimulation to assess the reduction in pain. Review articles were excluded. Overall, 1,030 potentially relevant articles were identified. After reading the titles and abstracts and assessing eligibility based on the full-text articles, 106 publications were finally included in our analysis. Overall, our findings suggested that rTMS is beneficial for treating neuropathic pain of various origins, such as central pain, pain from peripheral nerve disorders, fibromyalgia, and migraine. Although data on the use of rTMS for orofacial pain, including trigeminal neuralgia, phantom pain, low back pain, myofascial pain syndrome, pelvic pain, and complex regional pain syndrome, were promising, there was insufficient evidence to determine the efficacy of rTMS for treating these conditions. Therefore, further studies are needed to validate the effects of rTMS on pain relief in these conditions. Overall, this review will help guide clinicians in making informed decisions regarding whether rTMS is an appropriate option for managing various pain conditions.

Effect of the combination of high-frequency repetitive magnetic stimulation and neurotropin on injured sciatic nerve regeneration in rats

Repetitive magnetic stimulation is effective for treating posttraumatic neuropathies following spinal or axonal injury. Neurotropin is a potential treatment for nerve injuries like demyelinating diseases. This study sought to observe the effects of high-frequency repetitive magnetic stimulation, neurotropin and their combined use in the treatment of peripheral nerve injury in 32 adult male Sprague-Dawley rats. To create a sciatic nerve injury model, a 10 mm-nerve segment of the left sciatic nerve was cut and rotated through 180° and each end restored continuously with interrupted sutures. The rats were randomly divided into four groups. The control group received only a reversed autograft in the left sciatic nerve with no treatment. In the high-frequency repetitive magnetic stimulation group, peripheral high-frequency repetitive magnetic stimulation treatment (20 Hz, 20 min/d) was delivered for 10 consecutive days after auto-grafting. In the neurotropin group, neurotropin therapy (0.96 NU/kg per day) was administrated for 10 consecutive days after surgery. In the combined group, the combination of peripheral high-frequency repetitive magnetic stimulation (20 Hz, 20 min/d) and neurotropin (0.96 NU/kg per day) was given for 10 consecutive days after the operation. The Basso-Beattie-Bresnahan locomotor rating scale was used to assess the behavioral recovery of the injured nerve. The sciatic functional index was used to evaluate the recovery of motor functions. Toluidine blue staining was performed to determine the number of myelinated fibers in the distal and proximal grafts. Immunohistochemistry staining was used to detect the length of axons marked by neurofilament 200. Our results reveal that the Basso-Beattie-Bresnahan locomotor rating scale scores, sciatic functional index, the number of myelinated fibers in distal and proximal grafts were higher and axon lengths were longer in the high-frequency repetitive magnetic stimulation, neurotropin and combined groups compared with the control group. These measures were not significantly different among the high-frequency repetitive magnetic stimulation, neurotropin and combined groups. Therefore, our results suggest that peripheral high-frequency repetitive magnetic stimulation or neurotropin can promote the repair of injured sciatic nerves, but their combined use seems to offer no significant advantage. This study was approved by the Animal Ethics Committee of the Affiliated Changzhou No. 2 People’s Hospital of Nanjing Medical University, China on December 23, 2014 (approval No. 2014keyan002-01).

Pathophysiology of Central Poststroke Pain

Background and Purpose—

Central poststroke pain (CPSP) is a disabling condition in stroke patients, and evidence suggests that altered corticospinal and motor intracortical excitability occurs in neuropathic pain. The objective of this study was to investigate changes in motor cortex excitability and sensorimotor interaction and their correlates with clinical manifestations and alterations in somatosensory systems in CPSP patients.

Methods—

Fourteen patients with CPSP but no motor weakness were compared with age- and sex-matched healthy controls for motor cortex excitability and sensorimotor interaction assessed by transcranial magnetic stimulation to measure resting motor thresholds, short-interval intracortical inhibition, intracortical facilitation, and afferent inhibitions. The sensory pathway was evaluated by quantitative sensory testing, contact heat evoked potential, and somatosensory evoked potentials. Clinical pain and quality of life were assessed with validated tools.

Results—

The duration of CPSP was 3.3±3.0 years (ranging 0.5–10 years), and pain significantly impaired quality of life. Compared with the unaffected hemisphere, the stroke hemisphere had higher thermal thresholds, lower contact heat evoked potential amplitudes, and prolonged cortical somatosensory evoked potential latencies. There was no difference in resting motor thresholds between the stroke and unaffected hemisphere or between patients and controls. CPSP patients had a reduction in short-interval intracortical inhibition in the stroke hemisphere compared with that in the unaffected hemispheres of patients and controls. No changes were noted in afferent inhibitions between the stroke and unaffected hemispheres. The short-interval intracortical inhibition of the stroke hemisphere was negatively correlated with self-rated health on a visual analog scale and positively correlated with cortical somatosensory evoked potential latencies.

Conclusions—

CPSP patients with intact corticospinal tracts showed reduced motor intracortical inhibition in the stroke hemisphere, suggesting defective gamma-aminobutyric acid-ergic inhibition. This disinhibition was associated with impaired quality of life and was related to dorsal column–medial lemniscus pathway dysfunction.

Effects of continuous theta-burst stimulation of the primary motor and secondary somatosensory areas on the central processing and the perception of trigeminal nociceptive input in healthy volunteers

Supplemental Digital Content is Available in the Text.

Inactivating paired continuous theta-burst stimulation of the primary motor cortex but not on the secondary somatosensory area flattened the relationship between brain activation and stimulus strength while not impacting on the subjective perceptions.

Noninvasive modulation of the activity of pain-related brain regions by means of transcranial magnetic stimulation promises an innovative approach at analgesic treatments. However, heterogeneous successes in pain modulation by setting reversible “virtual lesions” at different brain areas point at unresolved problems including the optimum stimulation site. The secondary somatosensory cortex (S2) has been previously identified to be involved in the perception of pain-intensity differences. Therefore, impeding its activity should impede the coding of the sensory component of pain intensity, resulting in a flattening of the relationship between pain intensity and physical stimulus strength. This was assessed using inactivating spaced continuous theta-burst stimulation (cTBS) in 18 healthy volunteers. In addition, cTBS was applied on the primary motor cortex (M1) shown previously to yield moderate and variable analgesic effects, whereas sham stimulation at both sites served as placebo condition. Continuous theta-burst stimulation flattened the relationship between brain activation and stimulus strength, mainly at S2, the insular cortex, and the postcentral gyrus (16 subjects analyzed). However, these effects were observed after inactivation of M1 while this effect was not observed after inactivation of S2. Nevertheless, both the M1 and the S2-spaced cTBS treatment were not reflected in the ratings of the nociceptive stimuli of different strengths (17 subjects analyzed), contrasting with the clear coding of stimulus strength by these data. Hence, while modulating the central processing of nociceptive input, cTBS failed to produce subjectively relevant changes in pain perception, indicating that the method in the present implementation is still unsuitable for clinical application.

The effects of repetitive transcranial magnetic stimulation on the whole-brain functional network of postherpetic neuralgia patients

The effects of repetitive transcranial magnetic stimulation (rTMS), the clinical treatment for postherpetic neuralgia (PHN), on whole-brain functional network of PHN patients is not fully understood.To explore the effects of rTMS on the whole-brain functional network of PHN patients.10 PHN patients (male/female: 5/5 Age: 63-79 years old) who received rTMS treatment were recruited in this study. High-resolution T1-weighted and functional Magnetic Resonance Imaging (fMRI) were acquired before and after 10 consecutive rTMS sessions. The whole-brain functional connectivity networks were constructed by Pearson correlation. Global and node-level network parameters, which can reflect the topological organization of the brain network, were calculated to investigate the characteristics of whole-brain functional networks. Non-parametric paired signed rank tests were performed for the above network parameters with sex and age as covariates. P < .05 (with FDR correction for multi-comparison analysis) indicated a statistically significant difference. Correlation analysis was performed between the network parameters and clinical variables.The rTMS showed significant increase in characteristic path length and decrease of clustering coefficient, global, and local efficiency derived from the networks at some specific network sparsity, but it showed no significant difference for small-worldness. rTMS treatment showed significant differences in the brain regions related to sensory-motor, emotion, cognition, affection, and memory, as observed by changes in node degree, node betweenness, and node efficiency. Besides, node-level network parameters in some brain areas showed significant correlations with clinical variables including visual analog scales (VAS) and pain duration.rTMS has significant effects on the whole-brain functional network of PHN patients with a potential for suppression of sensory-motor function and improvement of emotion, cognition, affection, and memory functions.

Paired Associative Electroacupuncture and Transcranial Magnetic Stimulation in Humans

Pairing transcutaneous electric nerve stimulation (TENS) and transcranial magnetic stimulation (TMS) with specific stimulus-intervals induces associative motor plasticity at the primary motor cortex (M1). Electroacupuncture (EA) is an established medical technique in the eastern countries. This study investigates whether EA paired with TMS induces distinct M1 motor plasticity. Fifteen healthy, right-handed subjects (aged 23.6 ± 2.0 years, eight women) were studied. Two-hundred and twenty-five pairs of TMS of the left M1 preceded by right EA at acupoint “Neiguan” [Pericardium 6 (PC6), located 2 decimeters proximal from the wrist wrinkle] were respectively applied with the interstimulus interval (ISI) of individual somatosensory evoked potential (SSEP) N20 latency plus 2 ms (N20+2) and minus 5 ms (N20-5) with at least 1-week interval. The paired stimulation was delivered at a rate of 0.25 Hz. Sham TMS with a sham coil was adopted to examine the low-frequency EA influence on M1 in eleven subjects. M1 excitability was assessed by motor-evoked potential (MEP) recruitment curve with five TMS intensity levels, short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and cerebellar inhibition (CBI) at the abductor pollicis brevis (APB) muscle of the right hand before and after the EA-M1 paired associative stimulation (PAS). In addition, median nerve SSEPs and H-reflex were respectively measured to monitor somatosensory and spinal excitability. The MEP showed significantly facilitated after the sham EA-M1 PAS while tested with 80% of the TMS intensity producing on average 1 mV amplitude (i.e., MEP_{1 mV}) in the resting APB muscle. It was also facilitated while tested with 90% MEP_{1 mV} irrespective of the stimulation conditions. The SSEP showed a higher amplitude from the real EA-M1 PAS compared to that from the sham EA-M1 PAS. No significant change was found on SICI, ICF, CBI and H-reflex. Findings suggest that repetitive low frequency EA paired with real TMS did not induce spike-timing dependent motor plasticity but EA paired with sham TMS induced specific M1 excitability change. Complex sensory afferents with dispersed time locked to the sensorimotor cortical area could hamper instead of enhancing the induction of the spike-timing dependent plasticity (STDP) in M1.