Effect of Transcranial Direct Current Stimulation Combined With Patient-Controlled Intravenous Morphine Analgesia on Analgesic Use and Post-Thoracotomy Pain. A Prospective, Randomized, Double-Blind, Sham-Controlled, Proof-of-Concept Clinical Trial

The Application of tDCS to Treat Pain and Psychocognitive Symptoms in Cancer Patients: A Scoping Review

Background

The use of transcranial direct current stimulation (tDCS) to modulate pain, psychological aspects, and cognitive functions has increased in recent years. The present scoping review aims to investigate the use of tDCS in cancer patients and its significant impact on psychocognitive and pain related symptoms.

Methods

From the earliest available date to June 2023, a comprehensive search was conducted in three electronic scientific databases-PubMed, Scopus, and Embase-and other supplementary sources. Ten relevant studies were identified and included, comprising single case studies, randomized controlled trials, pilot studies, and one retrospective study. PRISMA guidelines for scoping reviews were followed.

Results

These studies investigated the use of tDCS to improve pain and psychocognitive aspects in patients with various types of cancer, including breast, oral, bladder, lung, pancreatic, head and neck cancer, hepatocellular carcinoma, and meningioma. Overall, the results suggest that tDCS has shown efficacy in relieving pain, reducing anxiety and depression, and improving cognitive function in cancer patients.

Conclusion

Due to the limited number and high heterogeneity of the existing literature in this field, more investigation and the establishment of standardized protocols would be required to obtain more conclusive evidence.

Transcranial Direct Current Stimulation Attenuates the Chronic Pain of Osteoarthritis in Rats via Reducing NMDAR2B Expressions in the Spinal Cord

OBJECTIVES

Osteoarthritis (OA) has been the common cause to lead to chronic pain. Transcranial direct current stimulation (tDCS) is effective in the treatment of chronic pain, but its analgesic mechanism is still unclear. This study observed the analgesic effects of tDCS in rats to explore the top-down analgesic modulation mechanism of tDCS.

METHODS

Monosodium iodoacetate (MIA) was used to establish OA chronic pain model. After 21 days, the rats received tDCS for 14 consecutive days (20 min/day). We assessed the pain-related behaviors of rats at different time points. Western blot and Immunohistochemistry were performed to observe the expression level of NMDAR2B in the spinal cord after tDCS treatment.

RESULTS

After MIA injection, rats developed apparent mechanical hyperalgesia and thermal hyperalgesia. However, the pain-related behaviors of rats were significantly improved after tDCS treatment. In addition, the expression of NMDAR2B and the proportion of positive stained cells of NMDAR2B were reversed by tDCS treatment.

CONCLUSIONS

The results demonstrated that tDCS can attenuate OA-induced chronic pain in rats via reducing NMDAR2B expressions in the spinal cord. We believe that this may be the result of tDCS participating in the top-down modulation of pain pathway in the endogenous analgesic system.

Cancer Pain and Non-Invasive Brain Stimulation-A Narrative Review

Background and Objectives: Pain is the most prevalent symptom in cancer patients. There is a paucity of data regarding non-invasive brain stimulation (NIBS) for the treatment of chronic pain in patients with cancer. The purpose of this article is to review the techniques of NIBS and present the published experiences of the oncological population. Materials and Methods: Databases including MEDLINE, Scopus, Web of Science, and the Cochrane Library were searched for articles on cancer patients with pain that was managed with non-invasive brain stimulation techniques. We included articles in English that were published from inception to January 2023. As studies were limited in number and had different designs and methodologies, a narrative review was considered as the best option to integrate data. Results: Four studies focusing on transcranial magnetic stimulation, six articles on transcranial direct current stimulation, and three articles regarding cranial electric stimulation were found and reviewed. Conclusions: Data are limited and not robust. Further studies in this field are required. Guidelines on NIBS for non-malignant chronic pain conditions provide good premises for cancer-related chronic pain.

Efficacy of transcranial direct current stimulation on postoperative delirium in elderly patients undergoing lower limb major arthroplasty: A randomized controlled trial

BACKGROUND

Postoperative delirium (POD) is a common and severe postoperative complication in elderly patients undergoing major surgery linked to increased morbidity and mortality. It is reported that transcranial direct current stimulation (tDCS) effectively enhances cognitive function and improves impaired consciousness.

OBJECTIVE

This study aimed to evaluate the efficacy of tDCS on POD in elderly patients undergoing lower limb major arthroplasty, including total hip arthroplasty (THA) or total knee arthroplasty (TKA).

METHODS

Patients aged ≥65 years scheduled for THA or TKA were randomly assigned to receive 2 mA tDCS for 20 min active-tDCS (n = 61) or sham-tDCS (n = 61). The primary outcome was the incidence of POD during the first 3 postoperative days.

RESULTS

All 122 patients (median age, 70 years; 80 women [65.6%]) completed the trial. The incident delirium risk was 4.9% (n = 3) vs. 19.7% (n = 12) in active-tDCS and sham-tDCS groups, respectively (relative risk, 0.250; 95% CI, 0.074 to 0.842; P = 0.013). Compared to the sham-tDCS group, the anxiety and depression scores of patients in the active-tDCS group were lower at 2 h and one day after surgery (P < 0.001 for each), and pain scores of patients in the active-tDCS group were lower during the first three days after surgery (P < 0.05).

CONCLUSION

One session of anodal tDCS over the left dorsolateral prefrontal cortex may decrease the incidence of POD in elderly patients undergoing lower limb major arthroplasty.

Effects of transcranial direct current stimulation in pain and opioid consumption after spine surgery

BACKGROUND

Transcranial direct current stimulation (tDCS) has shown promising results in alleviating different types of pain. The present study compares the efficacy of 3 sessions of anodal tDCS applied over primary motor area (M1) or the left dorsolateral prefrontal cortex (DLPFC) or sham on reducing pain and the total opioid consumption in post-operative spine surgery patients.

MATERIALS

Sixty-seven out of 75 eligible patients for post-operative spine surgery were randomly allocated into one of the three experimental groups. Group A received anodal tDCS applied over M1 cortex, group B over left DLPF cortex (2mA, 20 min) and group C received sham tDCS, all for 3 consecutive postoperative days. Patients were evaluated using a visual analogue scale (VAS) and adynamic visual analogue scale (DVAS) at baseline, and on each of the treatment days. The total morphine consumption over the 3 post-operative days was assessed.

RESULTS

Two-way repeated measures ANOVA showed no statistically significant difference in resting VAS between the 3 groups. However, there was significant pain improvement (P< 0.001) in DVAS in both active groups (group A and B) compared to the sham group (group C) in the post-operative period, with no significant difference between the active groups. Morphine consumption was significantly reduced in both active groups compared with the sham group, but there was no difference in consumption between the active groups.

CONCLUSION

There was a significant post-operative reduction in morphine consumption and DVAS scores after three sessions of active tDCS.

SIGNIFICANCE

tDCS is a promising tool for alleviating pain in the field of postoperative spine surgery.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Reimagining How We Treat Acute Pain: A Narrative Review

Acute pain may be influenced by biopsychosocial factors. Conditioned pain modulation, distraction, peripheral nerve stimulation, and cryoneurolysis may be helpful in its treatment. New developments in opioids, such as opioids with bifunctional targets and oliceridine, may be particularly suited for acute pain care. Allosteric modulators can enhance receptor subtype selectivity, offering analgesia with fewer and/or less severe side effects. Neuroinflammation in acute pain is caused by direct insult to the central nervous system and is distinct from neuroinflammation in degenerative disorders. Pharmacologic agents targeting the neuroinflammatory process are limited at this time. Postoperative pain is a prevalent form of acute pain and must be recognized as a global public health challenge. This type of pain may be severe, impede rehabilitation, and is often under-treated. A subset of surgical patients develops chronic postsurgical pain. Acute pain is not just temporally limited pain that often resolves on its own. It is an important subject for further research as acute pain may transition into more damaging and debilitating chronic pain. Reimagining how we treat acute pain will help us better address this urgent unmet medical need. 

Wireless Force-Inducing Neuronal Stimulation Mediated by High Magnetic Moment Microdiscs

Noninvasive manipulation of cell signaling is critical in basic neuroscience research and in developing therapies for neurological disorders and psychiatric conditions. Here, the wireless force-induced stimulation of primary neuronal circuits through mechanotransduction mediated by magnetic microdiscs (MMDs) under applied low-intensity and low-frequency alternating magnetic fields (AMFs), is described. MMDs are fabricated by top-down lithography techniques that allow for cost-effective mass production of biocompatible MMDs with high saturation and zero magnetic magnetic moment at remanence. MMDs are utilized as transducers of AMFs into mechanical forces. When MMDs are exposed to primary rat neuronal circuits, their magneto-mechanical actuation triggers the response of specific mechanosensitive ion channels expressed on the cell membranes activating ≈50% of hippocampal and ≈90% of cortical neurons subjected to the treatment. Mechanotransduction is confirmed by the inhibition of mechanosensitive transmembrane channels with Gd³⁺ . Mechanotransduction mediated by MMDs cause no cytotoxic effect to neuronal cultures. This technology fulfills the requirements of cell-type specificity and weak magnetic fields, two limiting factors in the development of noninvasive neuromodulation therapies and clinical equipment design. Moreover, high efficiency and long-lasting stimulations are successfully achieved. This research represents a fundamental step forward for magneto-mechanical control of neural activity using disc-shaped micromaterials with tailored magnetic properties.

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.

Methods and strategies of tDCS for the treatment of pain: current status and future directions

INTRODUCTION

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation technique that has been widely studied for the treatment of chronic pain. It is considered a promising and safe alternative pain therapy. Different targets have been tested, each having their own particular mechanisms for modulating pain perception.

AREAS COVERED

We discuss the current state of the art of tDCS to manage pain and future strategies to optimize tDCS' effects. Current strategies include primary motor cortex tDCS, prefrontal tDCS and tDCS combined with behavioral interventions while future strategies, on the other hand, include high-intensity tDCS, transcutaneous spinal direct current stimulation, cerebellar tDCS, home-based tDCS, and tDCS with extended number of sessions.

EXPERT COMMENTARY

It has been shown that the stimulation of the prefrontal and primary motor cortex is efficient for pain reduction while a few other new strategies, such as high-intensity tDCS and network-based tDCS, are believed to induce strong neuroplastic effects, although the underlying neural mechanisms still need to be fully uncovered. Hence, conventional tDCS approaches demonstrated promising effects to manage pain and new strategies are under development to enhance tDCS effects and make this approach more easily available by using, for instance, home-based devices.