Analgesic effects of repetitive transcranial magnetic stimulation on modified 2010 criteria-diagnosed fibromyalgia: Pilot study

Repetitive Transcranial Magnetic Stimulation in Fibromyalgia: Exploring the Necessity of Neuronavigation for Targeting New Brain Regions

Fibromyalgia and osteoarthritis are among the most prevalent rheumatic conditions worldwide. Nonpharmacological interventions have gained scientific endorsements as the preferred initial treatments before resorting to pharmacological modalities. Repetitive transcranial magnetic stimulation (rTMS) is among the most widely researched neuromodulation techniques, though it has not yet been officially recommended for fibromyalgia. This review aims to summarize the current evidence supporting rTMS for treating various fibromyalgia symptoms. Recent findings: High-frequency rTMS directed at the primary motor cortex (M1) has the strongest support in the literature for reducing pain intensity, with new research examining its long-term effectiveness. Nonetheless, some individuals may not respond to M1-targeted rTMS, and symptoms beyond pain can be prominent. Ongoing research aims to improve the efficacy of rTMS by exploring new brain targets, using innovative stimulation parameters, incorporating neuronavigation, and better identifying patients likely to benefit from this treatment. Summary: Noninvasive brain stimulation with rTMS over M1 is a well-tolerated treatment that can improve chronic pain and overall quality of life in fibromyalgia patients. However, the data are highly heterogeneous, with a limited level of evidence, posing a significant challenge to the inclusion of rTMS in official treatment guidelines. Research is ongoing to enhance its effectiveness, with future perspectives exploring its impact by targeting additional areas of the brain such as the medial prefrontal cortex, anterior cingulate cortex, and inferior parietal lobe, as well as selecting the right patients who could benefit from this treatment.

Role of Repetitive Transcranial Magnetic Stimulation in Treatment of Fibromyalgia: A Randomized Controlled Trial

Background and Objective

Fibromyalgia syndrome (FMS) is a chronic disease characterized by widespread, persistent musculoskeletal pain in association with impaired health-related quality of life. Repetitive transcranial magnetic stimulation (rTMS) is an emerging tool for the management of fibromyalgia. There is no standardized protocol of rTMS for the treatment of FMS, and both low- and high-frequency stimulation of the dorsolateral prefrontal cortex (DLPFC) are described in the literature with variable efficacy. The objective of this study was to determine the effectiveness of rTMS in people with fibromyalgia and compare the response of low- and high-frequency stimulation with sham stimulation.

Materials and Methods

This study was a single-blinded, randomized, placebo-controlled trial. Ninety patients with the diagnosis of FMS were randomly allocated into one of the following three groups: low-frequency (1 Hz) group, high-frequency (10 Hz) group, and sham group. Pain, depression, anxiety, and quality of life were measured using the Numerical Pain Rating Scale (NPRS), Hamilton Anxiety Rating Scale (HAM-A), Hamilton Depression Rating Scale (HDRS), and Revised Fibromyalgia Impact Questionnaire (FIQR) immediately following treatment as well as at 1 and 3 months after treatment. The data was statistically analyzed using Statistical Package for the Social Sciences version 23 software. P value < 0.05 was considered statistically significant.

Results

Intergroup analysis revealed a significant improvement in NPRS, HAM-A, HDRS, and FIQR scores in both low- and high- frequency groups immediately following treatment and for 3 months after treatment. No significant difference in the efficacy of low- and high-frequency stimulation was noticed.

Conclusions

rTMS is an effective mode of treatment in people with FMS. Both low and high frequencies of stimulation at DLPFC are equally effective in reducing pain and associated symptoms.

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.

Cortical stimulation for chronic pain: from anecdote to evidence

Epidural stimulation of the motor cortex (eMCS) was devised in the 1990's, and has now largely supplanted thalamic stimulation for neuropathic pain relief. Its mechanisms of action involve activation of multiple cortico-subcortical areas initiated in the thalamus, with involvement of endogenous opioids and descending inhibition toward the spinal cord. Evidence for clinical efficacy is now supported by at least seven RCTs; benefits may persist up to 10 years, and can be reasonably predicted by preoperative use of non-invasive repetitive magnetic stimulation (rTMS). rTMS first developed as a means of predicting the efficacy of epidural procedures, then as an analgesic method on its own right. Reasonable evidence from at least six well-conducted RCTs favors a significant analgesic effect of high-frequency rTMS of the motor cortex in neuropathic pain (NP), and less consistently in widespread/fibromyalgic pain. Stimulation of the dorsolateral frontal cortex (DLPFC) has not proven efficacious for pain, so far. The posterior operculo-insular cortex is a new and attractive target but evidence remains inconsistent. Transcranial direct current stimulation (tDCS) is applied upon similar targets as rTMS and eMCS; it does not elicit action potentials but modulates the neuronal resting membrane state. tDCS presents practical advantages including low cost, few safety issues, and possibility of home-based protocols; however, the limited quality of most published reports entails a low level of evidence. Patients responsive to tDCS may differ from those improved by rTMS, and in both cases repeated sessions over a long time may be required to achieve clinically significant relief. Both invasive and non-invasive procedures exert their effects through multiple distributed brain networks influencing the sensory, affective and cognitive aspects of chronic pain. Their effects are mainly exerted upon abnormally sensitized pathways, rather than on acute physiological pain. Extending the duration of long-term benefits remains a challenge, for which different strategies are discussed in this review.

Efficacy of Repetitive Transcranial Magnetic Stimulation in Fibromyalgia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

This article aimed to investigate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in fibromyalgia. The PubMed, Medline, Cochrane Library, and Web of Science databases were searched for articles published through 14 August 2021. We enrolled only randomized controlled trials. The Cochrane Collaboration risk of bias tool was used for quality assessment. Outcomes were analyzed as standardized mean differences (SMDs) with 95% CIs. The beta coefficient and p value were adopted for meta-regression. We included 18 studies comprising 643 participants. A significant reduction in disease influence, as measured by the Fibromyalgia Impact Questionnaire, was observed (SMD, −0.700, 95% CI, −1.173 to −0.228), and the reduction was larger in older patients (β = −0.1327, p = 0.008). The effect persisted at least two weeks after the final treatment session (SMD, −0.784, 95% CI, −1.136 to −0.432). Reductions in pain, depression, and anxiety were discovered, which persisted for at least two weeks after the last intervention. The effects on pain and depression remained significant up to one and a half months after the final session. No serious adverse events were reported by the included articles. In conclusion, our systematic review and meta-analysis revealed that rTMS is safe and effective for managing multiple domains of fibromyalgia-related symptoms and older patients may have a stronger treatment effect. Larger randomized controlled trials with sufficient male populations are warranted to confirm our findings, detect rare adverse events, and determine the optimal stimulation parameters.

Repetitive transcranial magnetic stimulation for fibromyalgia patients: A Systematic Review with Meta-Analysis

OBJECTIVE

Fibromyalgia is a poorly understood pain syndrome. Repetitive transcranial magnetic stimulation is a noninvasive brain stimulation therapy and is commonly applied for the management of fibromyalgia. However, controversy regarding its efficacy remains. Therefore, a meta-analysis was conducted to evaluate the effectiveness of repetitive transcranial magnetic stimulation (rTMS) for fibromyalgia syndrome.

METHOD

Four medical databases and one physiotherapy database were screened for randomized controlled trials. A systematic review and meta-analysis was performed. Numerical Pain Rating Scale (NPRS), Beck Depression Inventory (BDI), Hospital Anxiety and Depression Scale (HADS) anxiety score, Pain Catastrophizing Scale (PCS), Fatigue Severity Scale (FSS), Short Form-36 general health survey mental score, and Fibromyalgia Impact Questionnaire (FIQ) were set as outcome measures.

RESULTS

Analysis of 14 studies and 433 participants indicated that rTMS exerted more favorable effects on the NPRS than sham rTMS after treatment (standardized mean difference = -0.49, 95% confidence interval = -0.86 to - 0.13, P = 0.008, I2 = 68%) and FIQ (standardized mean difference = -0.50, 95% confidence interval = -0.75 to - 0.25, P = 0.0001, I2 = 28%). However, the BDI, FSS, PCS, mood index, and HADS scores showed no significant difference compared with sham rTMS after treatment. The mean methodological quality of included studies was an acceptable score of 8.5 based on the PEDro scale, suggesting the validity of our conclusions.

CONCLUSION

This study demonstrated that rTMS relieved pain and enhanced quality of life of patients with fibromyalgia; however, it did not improve anxiety, depression, and other symptoms based on current reports.

Moving back in the brain to drive the field forward: Targeting neurostimulation to different brain regions in animal models of depression and neurodegeneration

BACKGROUND

Repetitive transcranial magnetic stimulation is a promising noninvasive therapeutic tool for a variety of brain-related disorders. However, most therapeutic protocols target the anterior regions, leaving many other areas unexplored. There is a substantial therapeutic potential for stimulating various brain regions, which can be optimized in animal models.

NEW METHOD

We illustrate a method that can be utilized reliably to stimulate the anterior or posterior brain in freely moving rodents. A coil support device is surgically attached onto the skull, which is used for consistent coil placement over the course of up to several weeks of stimulation sessions.

RESULTS

Our methods provide reliable stimulation in animals without the need for restraint or sedation. We see little aversive effects of support placement and stimulation. Computational models provide evidence that moving the coil support location can be utilized to target major stimulation sites in humans and mice.

SUMMARY OF FINDINGS WITH THIS METHOD

Animal models are key to optimizing brain stimulation parameters, but research relies on restraint or sedation for consistency in coil placement. The method described here provides a unique means for reliable targeted stimulation in freely moving animals. Research utilizing this method has uncovered changes in biochemical and animal behavioral measurements as a function of brain stimulation.

CONCLUSIONS

The majority of research on magnetic stimulation focuses on anterior regions. Given the substantial network connectivity throughout the brain, it is critical to develop a reliable method for stimulating different regions. The method described here can be utilized to better inform clinical trials about optimal treatment localization, stimulation intensity and number of treatment sessions, and provides a motivation for exploring posterior brain regions for both mice and humans.

High-frequency rTMS over the dorsolateral prefrontal cortex on chronic and provoked pain: A systematic review and meta-analysis

BACKGROUND

High-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) has demonstrated mixed effects on chronic and provoked pain.

OBJECTIVES/METHODS

In this study, a meta-analysis was conducted to characterise the potential analgesic effects of high-frequency rTMS over the DLPFC on both chronic and provoked pain.

RESULTS

A total of 626 studies were identified in a systematic search. Twenty-six eligible studies were included for the quantitative review, among which 17 modulated chronic pain and the remaining investigated the influence on provoked pain. The left side DLPFC was uniformly targeted in the chronic pain studies. While our data identified no overall effect of TMS across chronic pain conditions, there was a significant short-term analgesia in neuropathic pain conditions only (SMD = -0.87). In terms of long-lasting analgesia, there was an overall pain reduction in the midterm (SMD = -0.53, 24.6 days average) and long term (SMD = -0.63, 3 months average) post DLPFC stimulation, although these effects were not observed within specific chronic pain conditions. Surprisingly, the number of sessions was demonstrated to have no impact on rTMS analgesia. In the analysis of provoked pain, our data also indicated a significant analgesic effect following HF-rTMS over the DLPFC (SMD = -0.73). Importantly, we identified a publication bias in the studies of provoked pain but not for chronic pain conditions.

CONCLUSIONS

Overall, our findings support that HF-DLPFC stimulation is able to induce an analgesic effect in chronic pain and in response to provoked pain. These results highlight the potential of DLPFC-rTMS in the management of certain chronic pain conditions and future directions are discussed to enhance the potential long-term analgesic effects.

Repetitive transcranial magnetic stimulation (rTMS) versus transcranial direct current stimulation (tDCS) in the management of patients with fibromyalgia: A randomized controlled trial

OBJECTIVES

The aim of this study was to compare the effects of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) on pain and quality of life in patients with fibromyalgia.

METHODS

Thirty participants were randomized into two groups of 15 patients, to receive 3 sessions of either high-frequency (10 Hz) rTMS or 2 mA, 20 min anodal transcranial direct current stimulation over the left dorsolateral prefrontal cortex (DLPFC) over 1 week. Pain was assessed using a Visual Analog Scale (VAS) before treatment, immediately after treatment, 6 and 12 weeks later. Quality of life was evaluated using the Revised Fibromyalgia Impact Questionnaire (FIQR) and psychiatric symptoms were measured using the Depression Anxiety Stress Scale-21 Item (DASS-21) before treatment, and 6 and 12 weeks after treatment.

RESULTS

For the VAS there was a significant time-group interaction, showing that the behavior of two groups differed regarding changes of VAS in favor of the RTMS group (df = 1.73, F = 4.80, p = <0.016). Time-group interaction effect on DASS-21 and FIQR was not significant. 66.6% of patients in rTMS group and 26.6% of patients in tDCS group experienced at least a 30% reduction of VAS from baseline to last follow-up (p = 0.028).

DISCUSSION

With the methodology used in this study, both rTMS and tDCS were safe modalities and three sessions of rTMS over DLPFC had greater and longer lasting analgesic effects compared to tDCS in patients with FM. However, considering the limitations of this study, further studies are needed to explore the most effective modality.

Effects of High-Frequency Neuronavigated Repetitive Transcranial Magnetic Stimulation in Fibromyalgia Syndrome: A Double-Blinded, Randomized Controlled Study

OBJECTIVE

The primary aim of the study was to investigate the effect of 10-Hz repetitive transcranial magnetic stimulation to the left dorsolateral prefrontal cortex on pain in fibromyalgia. Secondary aims were to determine its effects on stiffness, fatigue, quality of life, depression/anxiety, and cognitive functions.

DESIGN

Twenty participants were randomized into two groups. Group A received 10-Hz repetitive transcranial magnetic stimulation to left dorsolateral prefrontal cortex and group B received sham stimulation. Visual analog scale for pain, visual analog scale-stiffness, Fibromyalgia Impact Questionnaire, and Fatigue Severity Scale were assessed at the baseline, 2nd, and 6th weeks, whereas Hospital Anxiety Depression Scale and Addenbrooke's cognitive examination were assessed at the baseline and 6th week.

RESULTS

There was no significant difference in visual analog scale-pain and Fatigue Severity Scale within and between groups over time (P > 0.05). In group A, significant improvement was found in visual analog scale-stiffness and fibromyalgia impact questionnaire at the 2nd week in comparison to the baseline (P < 0.05). However, no significant difference was detected in comparison with group B. There was no significant change in Hospital Anxiety Depression Scale scores between and within groups. All cognitive measures were similar in terms of differences from baseline between the groups (P > 0.05).

CONCLUSIONS

High-frequency repetitive transcranial magnetic stimulation to the left dorsolateral prefrontal cortex did not show any significant beneficial effect on pain, stiffness, fatigue, quality of life, mood, and cognitive state over sham stimulation.

New Developments in Non-invasive Brain Stimulation in Chronic Pain

Purpose of Review

The goal of this review is to present a summary of the recent literature of a non-invasive brain stimulation (NIBS) to alleviate pain in people with chronic pain syndromes. This article reviews the current evidence for the use of transcranial direct current (tDCS) and repetitive transcranial magnetic stimulation (rTMS) to improve outcomes in chronic pain. Finally, we introduce the reader to novel stimulation methods that may improve therapeutic outcomes in chronic pain.

Recent Findings

While tDCS is approved for treatment of fibromyalgia in Canada and the European Union, no NIBS method is currently approved for chronic pain in the United States. Increasing sample sizes in randomized clinical trials (RCTs) seems the most efficient way to increase confidence in initial promising results. Trends at funding agencies reveal increased interest and support for NIBS such as recent Requests for Application from the National Institutes of Health. NIBS in conjunction with cognitive behavioral therapy and physical therapy may enhance outcomes in chronic pain. Novel stimulation methods, such as transcranial ultrasound stimulation, await rigorous study in chronic pain.

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.

Differential Neuroplastic Changes in Fibromyalgia and Depression Indexed by Up-Regulation of Motor Cortex Inhibition and Disinhibition of the Descending Pain System: An Exploratory Study

Background: Major depressive disorder (MDD) and fibromyalgia (FM) present overlapped symptoms. Although the connection between these two disorders has not been elucidated yet, the disruption of neuroplastic processes that mediate the equilibrium in the inhibitory systems stands out as a possible mechanism. Thus, the purpose of this cross-sectional exploratory study was: (i) to compare the motor cortex inhibition indexed by transcranial magnetic stimulation (TMS) measures [short intracortical inhibition (SICI) and intracortical facilitation (ICF)], as well as the function of descending pain modulatory systems (DPMS) among FM, MDD, and healthy subjects (HS); (ii) to compare SICI, ICF, and the role of DPMS evaluated by the change on Numerical Pain Scale (NPS) during the conditioned pain modulation test (CPM-test) between FM and MDD considering the BDNF-adjusted index; (iii) to assess the relationship between the role of DPMS and the BDNF-adjusted index, despite clinical diagnosis. Patients and Methods: A cohort of 63 women, aged 18 to 75 years [FM (n = 18), MDD (n = 19), and HC (n = 29)]. Results: The MANCOVA analysis revealed that the mean of SICI was 53.40% larger in FM compared to MDD [1.03 (0.50) vs. 0.55 (0.43)] and 66.99% larger compared to HC [1.03 (0.50) vs. 0.34 (0.19)], respectively. The inhibitory potency of the DPMS assessed by the change on the NPS during CPM-test was 112.29 % lower in the FM compared to MDD [0.22 (1.37) vs. -0.87 (1.49)]. The mean of BDNF from FM compared to MDD was 35.70% higher [49.82 (16.31) vs. 14.12 (8.86)]. In FM, the Spearman's coefficient between the change in the NPS during CPM-test with the SICI was Rho = -0.49, [confidence interval (CI) 95%; -0.78 to -0.03]. The BDNF-adjusted index was positively correlated with the disinhibition of the DPMS. Conclusion: These findings support the hypothesis that in FM a deteriorated function of cortical inhibition, indexed by a higher SICI parameter, a lower function of the DPMS, together with a higher level of BDNF indicate that FM has different pathological substrates from depression. They suggest that an up-regulation phenomenon of intracortical inhibitory networks associated with a disruption of the DPMS function occurs in FM.