Relieving pain in rheumatology patients: Repetitive transcranial magnetic stimulation (rTMS), a developing approach

Non-Invasive Electric and Magnetic Brain Stimulation for the Treatment of Fibromyalgia

Although fibromyalgia is defined by its core muscular nociceptive component, it also includes multiple dysfunctions that involve the musculoskeletal, gastrointestinal, immune, endocrine, as well as the central and peripheral nervous systems, amongst others. The pathogenic involvement of the nervous system and the numerous neurological and neuroinflammatory symptoms of this disease may benefit from neuromodulatory stimulation techniques that have been shown to be effective and safe in diverse nervous system pathologies. In this systematic review, we outline current evidence showing the potential of non-invasive brain stimulation techniques, such as therapeutic strategies in fibromyalgia. In addition, we evaluate the contribution of these tools to the exploration of the neurophysiological characteristics of fibromyalgia. Considering that the pathogenesis of this disease is unknown, these approaches do not aim to causally treat this syndrome, but to significantly reduce a range of key symptoms and thus improve the quality of life of the patients.

Non-invasive Brain Stimulation for Chronic Pain: State of the Art and Future Directions

As a technique that can guide brain plasticity, non-invasive brain stimulation (NIBS) has the potential to improve the treatment of chronic pain (CP) because it can interfere with ongoing brain neural activity to regulate specific neural networks related to pain management. Treatments of CP with various forms of NIBS, such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), using new parameters of stimulation have achieved encouraging results. Evidence of moderate quality indicates that high-frequency rTMS of the primary motor cortex has a clear effect on neuropathic pain (NP) and fibromyalgia. However, evidence on its effectiveness regarding pain relief in other CP conditions is conflicting. Concerning tDCS, evidence of low quality supports its benefit for CP treatment. However, evidence suggesting that it exerts a small treatment effect on NP and headaches is also conflicting. In this paper, we describe the underlying principles behind these commonly used stimulation techniques; and summarize the results of randomized controlled trials, systematic reviews, and meta-analyses. Future research should focus on a better evaluation of the short-term and long-term effectiveness of all NIBS techniques and whether they decrease healthcare use, as well as on the refinement of selection criteria.

Alternate sessions of transcranial direct current stimulation (tDCS) reduce chronic pain in women affected by chikungunya. A randomized clinical trial

CONTEXT

Thousands of people worldwide have been infected by the chikungunya virus (CHIKV), and the persistence of joint pain symptoms has been considered the main problem. Neuromodulation techniques such as transcranial direct current stimulation (tDCS) act on brain areas involved in the processing of chronic pain. It was previously demonstrated that tDCS for five consecutive days significantly reduced pain in the chronic phase of chikungunya (CHIK).

OBJECTIVE

To analyze the effect of alternate tDCS sessions on pain and functional capacity in individuals affected by CHIK.

METHODS

In a randomized clinical trial, 58 women in the chronic phase of CHIK were divided into two groups: active-tDCS (M1-S0, 2 mA, 20 min) and sham-tDCS. The Visual Analogue Scale (VAS) and the Brief Pain Inventory (BPI) were used to assess pain, while the Health Assessment Questionnaire (HAQ) assessed functional capacity. These scales were used before and after six sessions of tDCS in nonconsecutive days on the primary motor cortex, and at follow-up consultation 7 and 15 days after the last session. A repeated measures mixed-model ANOVA was used for comparison between groups (significant p-values < 0.05).

RESULTS

A significant pain reduction (Z [3, 171] = 14.303; p < 0.0001) was observed in the tDCS group compared to the sham group; no significant difference in functional capacity was observed (Z [1.57] = 2.797; p = 0.1).

CONCLUSION

Our results suggest that six nonconsecutive sessions of active tDCS on M1 reduce pain in chronic CHIKV arthralgia.

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.

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

AIM

Fibromyalgia is often comorbid with depression, and less than half those patients achieve satisfactory improvement after adequate pharmacological intervention. The investigation of repetitive transcranial magnetic stimulation (rTMS) at left dorsolateral prefrontal cortex for modified-2010 American College of Rheumatology (ACR) fibromyalgia and major depressive disorder (MDD) is still in its infancy.

METHODS

In this double-blind, randomized, sham-control study, subjects diagnosed with ACR-2010 fibromyalgia and DSM-IV-TR MDD were recruited and received either active or sham interventions for 2 weeks. Hamilton Depression Rating Scale (HDRS) and the 10-cm visual analogue pain scale were evaluated at baseline, week 1, and week 2. Multivariable generalized estimating equations analysis was performed for the association between depression and pain scores at each checkpoint.

RESULTS

Twenty subjects were recruited. There was a significant difference over the 2 weeks between the rTMS and sham stimulation groups (P = 0.029), but subgroup analyses were further performed due to significant interaction of group and HDRS on pain outcomes (P = 0.020). The active group had significant improvement in pain at week 2 compared with week 1 (P = 0.021), but the control group did not have any improvement in pain (P = 0.585). Of the mild-moderate depression patients, the pain score in the active group was significantly lower than in the sham group at week 1 (P = 0.001) and at week 2 (P < 0.001). For the severe depression group, there was significantly lower pain over the 2 weeks in the active group (P = 0.045) but the sham group had significantly relapsing pain at week 2 (P < 0.001).

CONCLUSION

Left prefrontal rTMS has an analgesic effect in modified-ACR 2010-defined fibromyalgia and MDD patients. Further investigation is required, however, in order to determine how to regulate the different rTMS treatment protocols according to individual baseline depression severity in patients with MDD and fibromyalgia.

Strong opioids for noncancer pain due to musculoskeletal diseases: Not more effective than acetaminophen or NSAIDs

The classification of morphine as a step III analgesic, based on pharmacological data, creates a strong bias toward a belief in the efficacy of this drug. However, double-blind emergency-room trials showed similar levels of pain relief with intravenous acetaminophen as with intravenous morphine in patients with renal colic, low back pain or acute limb pain. In patients with chronic noncancer low back pain, morphine and other strong opioids in dosages of up to 100mg/day were only slightly more effective than their placebos, no more effective than acetaminophen, and somewhat less effective than nonsteroidal anti-inflammatory drugs (NSAIDs). In patients with osteoarthritis, strong opioids were not more effective than NSAIDs and, in some studies, than placebos. The only randomized controlled trial in patients with sciatica found no difference with the placebo. Chronic use of strong opioids can induce hyperalgesia in some patients. Hyperpathia with increased sensitivity to cold leading the patient to request higher dosages should suggest opioid-induced hyperalgesia. Pain specialists in the US have issued a petition asking that strong opioids be used in dosages no higher than 100mg/day of morphine-equivalent, in an effort to decrease the high rate of mortality due to the misuse and abuse of strong opioids (10,000 deaths/year in the US). Healthcare providers often overestimate the efficacy of step III analgesics, despite pain score decreases of only 0.8 to 1.2 points.

Transcranial magnetic stimulation for chronic pain

Current data suggest that transcranial magnetic stimulation (TMS) has the potential to be an effective and complimentary treatment modality for patients with chronic neuropathic pain syndromes. The success of TMS for pain relief depends on the parameters of the stimulation delivered, the location of neural target, and duration of treatment. TMS can be used to excite or inhibit underlying neural tissue that depends on long-term potentiation and long-term depression, respectively. Long-term randomized controlled studies are warranted to establish the efficacy of repetitive TMS in patients with various chronic pain syndromes.