Cerebral blood flow-based evidence for mechanisms of low- versus high-frequency transcutaneous electric acupoint stimulation analgesia: a perfusion fMRI study in humans

Comparison of Low-Frequency or High-Frequency Electrical Acupoint Stimulation on Hypotension After Spinal Anesthesia in Parturients: A Prospective Randomized Controlled Clinical Trial

Objective: To investigate whether transcutaneous electrical acupoint stimulation (TEAS) at PC6 could reduce hypotension after spinal anesthesia (SA) in parturients and to compare the effect of TEAS at different frequencies. Methods: From February 20, 2023, to August 29, 2023, 90 parturients scheduled for c-section under SA were randomly assigned to receive no treatment (Control), TEAS at high frequency (TEAS-HF), or TEAS at low frequency (TEAS-LF). Treatments started immediately after SA and lasted for 30 min. The primary endpoint was incidence of hypotension by 30 min after SA. Secondary endpoints included lowest systolic blood pressure (SBP) during 30 min after SA, dose of ephedrine, dose of atropine, Apgar score at 1 min, and adverse events, including nausea, vomiting, dizziness, dyspnea, and chest congestion. Results: In the TEAS-HF group, the incidence of hypotension by 30 min after SA was lower (13.3%) than in the Control (53.3%, p = 0.001; OR 1.9, 95% confidence interval [CI]: 1.2-2.8) and TEAS-LF group (40.0%, p = 0.02, OR 1.4, 95% CI: 1.0-2.0). The lowest SBP during 30 min after SA was higher in the TEAS-HF group (100.0 ± 9.4 mm Hg) than in the Control group (91.5 ± 16.5 mm Hg) and TEAS-LF group (93.9 ± 16.6 mm Hg). Patients who received TEAS showed a lower score of nausea and vomiting (both p = 0.02). Patients in the group TEAS-HF showed a lower incidence of dizziness, dyspnea, and of chest congestion than those in the other two groups. There was no difference with respect to atropine consumption and neonatal Apgar score. Conclusions: TEAS-HF at PC6 reduced hypotension after SA in parturients, while TEAS-LF did not. Trial registration: ClinicalTrials.gov (NCT05724095).

Cerebral cortex Functional Networks of Transdermal Electrical Stimulation at Daling (PC7) Acupoint

The cerebral cortex functional network of Electroencephalogram (EEG) signals during transcutaneous electrical acupoint stimulation (TEAS) on 21 healthy subjects was constructed by using three modules: standard low-resolution brain electromagnetic tomography (sLORETA), phase-locking value (PLV), and complex network. We investigated the brain functional network triggered by PC7 stimulation by comparing with resting state and non-acupoint stimulation. The results showed that the PC7 stimulation mainly activated frontal lobe and temporal lobe including prefrontal cortex (BA10), insular lobe (BA13), temporal gyrus (BA22), anterior cingulate cortex (BA32), temporal pole (BA38), dorsolateral prefrontal cortex (BA46), and inferior frontal cortex (BA47), which are all closely linked to cognition, spirit, and emotion in brain. Furthermore, the degrees of node in frontal, temporal, and whole brain are increased significantly or extreme significantly with p < 0.05, p < 0.05, and p < 0.01, respectively; clustering coefficient in frontal, temporal, and whole brain are all statistically significant (p < 0.05). The information transmission efficiency of cerebral cortex has been greatly improved. During PC7 stimulation, the topological changes in the activation of cerebral regions and cortical functional networks are consistent with the therapeutic effect, which may provide theoretical support for acupoint stimulation to regulate nerve function.

Neuroimaging in the Understanding of Acupuncture Analgesia: A Review of Acupuncture Neuroimaging Study Based on Experimental Pain Models

With the development of real-time and visualized neuroimaging techniques, the studies on the central mechanism of acupuncture analgesia gain increasing attention. The experimental pain models have been widely used in acupuncture-analgesia neuroimaging studies with quantitative and controlled advantages. This review aimed to analyze the study design and main findings of acupuncture neuroimaging studies to provide reference for future study. The original studies were collected and screened in English databases (PubMed, EMBASE, and Cochrane Library) and Chinese databases (Chinese Nation Knowledge Infrastructure, Chinese Biomedical Literature Database, the Chongqing VIP Database, and Wanfang Database). As a result, a total of 27 articles were included. Heat stimulation and electroacupuncture were the mostly used pain modeling method and acupuncture modality, respectively. The neuroimaging scanning process can be divided into two models and five subtypes. The anterior cingulate cortex and insula were the most commonly reported brain regions involved in acupuncture analgesia with experimental pain models.

Effects of Transcutaneous Electrical Acupoint Stimulation on Motor Functions and Self-Care Ability in Children with Cerebral Palsy

OBJECTIVES

To observe the effects of transcutaneous electrical acupoint stimulation (TEAS) in improving motor functions and self-care abilities in children with cerebral palsy in their early childhood.

DESIGN

A preliminary, prospective, cohort study.

SETTINGS/LOCATION

Multicenter.

SUBJECTS

Children aged 2-6 years old.

INTERVENTIONS

Twenty-three children were included in the study and randomly assigned to a control group ([CG] N = 11) or a therapeutic group ([TG] N = 12). In the TG, children were treated with TEAS (Shousanli [LI10] and Waiguan [SJ5]) plus the exercise therapy, while in the control group, they were treated with sham TEAS plus exercise therapy. Therapies were performed five days per week for eight weeks.

OUTCOME MEASURES

The Gross Motor Function Measure (GMFM) and the Functional Independent Measurement for children (WeeFIM) were used to evaluate motor functions and self-care abilities before and after the therapies.

RESULTS

Greater improvements were observed in the TG concerning all the measurements, although without statistical differences. The increments of the GMFM score and the WeeFIM motor, self-care and total scores were 36.08 ± 18.34 (26%), 16.17 ± 8.21 (33%), 7.67 ± 3.42 (40%) and 20.33 ± 10.08 (28%) in the TG, while 22.73 ± 16.54 (17%), 9.09 ± 9.43 (19%), 5.64 ± 6.73 (29%) and 12.82 ± 11.77 (18%) in the CG, respectively. No statistically significant correlations were shown between functional improvements and the demographics in the TG or the CG. The GMFM improvement was not statistically correlated with the improvements of the WeeFIM motor, self-care or total scores. However, the WeeFIM motor, self-care and total score were significantly positively correlated with one another in both groups (P < 0.01). No adverse effect was recorded during the study.

CONCLUSION

TEAS may be effective in improving motor functions and self-care abilities in children with cerebral palsy, in addition to conventional exercise therapy. Larger samples are required to confirm the efficacies.

Sustained Effects of Acupuncture Stimulation Investigated with Centrality Mapping Analysis

Acupuncture can have instant and sustained effects, however, its mechanisms of action are still unclear. Here, we investigated the sustained effect of acupuncture by evaluating centrality changes in resting-state functional magnetic resonance imaging after manually stimulating the acupuncture point ST36 at the lower leg or two control point locations (CP1 same dermatome, CP2 different dermatome). Data from a previously published experiment evaluating instant BOLD effects and S2-seed-based resting state connectivity was re-analyzed using eigenvector centrality mapping and degree centrality mapping. These data-driven methods might add new insights into sustained acupuncture effects on both global and local inter-region connectivity (centrality) by evaluating the summary of connections of every voxel. We found higher centrality in parahippocampal gyrus and middle temporal gyrus after ST36 stimulation in comparison to the two control points. These regions are positively correlated to major hubs of the default mode network, which might be the primary network affected by chronic pain. The stronger integration of both regions within the whole-brain connectome after stimulation of ST36 might be a potential contributor to pain modulation by acupuncture. These findings highlight centrality mapping as a valuable analysis for future imaging studies investigating clinically relevant outcomes associated with physiological response to acupuncture stimulation.

CLINICAL TRIAL REGISTRATION

NCT01079689, ClinicalTrials.gov.

Manual acupuncture at the SJ5 (Waiguan) acupoint shows neuroprotective effects by regulating expression of the anti-apoptotic gene Bcl-2

Acupuncture at the SJ5 (Waiguan) acupoint has neuroprotective effects in cerebral infarction, but the underlying mechanism remains poorly understood. Here, we analyzed gene expression in healthy rat cerebellum using a pathway-focused DNA microarray to screen 113 genes associated with 18 signal transduction pathways. After 20 minutes of acupuncture at SJ5, the expression of Bcl-2 and Birc1b mRNA was markedly increased. This was confirmed by real-time reverse transcription PCR. Furthermore, western blot analysis showed that Bcl-2 protein expression remained high in the cerebellum until at least 2 hours after cessation of acupuncture. These findings indicate that acupuncture at SJ5 exerts neuroprotective effects by regulating the expression of anti-apoptotic gene Bcl-2.

Involvement of hippocampal acetylcholinergic receptors in electroacupuncture analgesia in neuropathic pain rats

BACKGROUND

Cumulating evidence has shown a close correlation between electroacupuncture stimulation (EAS) frequency-specific analgesic effect and central opioid peptides. However, the actions of hippocampal acetylcholinergic receptors have not been determined. This study aims to observe the effect of different frequencies of EAS on the expression of hippocampal muscarinic and nicotinic acetylcholinergic receptors (mAChRs, nAChRs) in neuropathic pain rats for revealing their relationship.

METHODS

Forty male Wistar rats were randomly and equally divided into sham, CCI model, 2, 2/15 and 100 HzEA groups. The neuropathic pain model was established by ligature of the left sciatic nerve to induce chronic constriction injury (CCI). EAS was applied to bilateral Zusanli (ST36) and Yanglingquan (GB34) for 30 min, once daily for 14 days except weekends. The mechanical pain thresholds (withdrawal latencies, PWLs) of bilateral hindpaws were measured. The expression levels of hippocampal M1 and M2 mAChR, and α4 and β2 nAChR genes and proteins were detected by quantitative RT-PCR and Western blot, separately. The involvement of mAChR and nAChR in the analgesic effect of EAS was confirmed by intra-hippocampal microinjection of M1mAChR antagonist (Pirenzepine) and α4β2 nAChR antagonist (dihydro-beta-erythroidine) respectively.

RESULTS

Following EAS, the CCI-induced increase of difference values of bilateral PWLs on day 6 and 14 was significantly reduced (P < 0.05), with 2/15 Hz being greater than 100 Hz EAS on day 14 (P < 0.05). After 2 weeks' EAS, the decreased expression levels of M1 mAChR mRNA of both 2 and 2/15 Hz groups and M1 mAChR protein of the three EAS groups, α4 AChR mRNA of the 2/15 Hz group and β2 nAChR protein of the three EAS groups were considerably increased (P < 0.05), suggesting an involvement of M1 mAChR and β2 nAChR proteins in EAS-induced pain relief. No significant changes were found in the expression of M2 mAChR mRNA and protein, α4 nAChR protein and β2 nAChR mRNA after CCI and EAS (P > 0.05). The analgesic effect of EAS was abolished by intra-hippocampal microinjection of M1mAChR and α4β2 nAChR antagonists respectively.

CONCLUSIONS

EAS of ST36-GB34 produces a cumulative analgesic effect in neuropathic pain rats, which is frequency-dependent and probably mediated by hippocampal M1 mAChR and β2 nAChR proteins.

The Effects of High-Frequency Transcutaneous Electrical Nerve Stimulation for Dental Professionals with Work-Related Musculoskeletal Disorders: A Single-Blind Randomized Placebo-Controlled Trial

Work-related musculoskeletal symptom disorders (WMSDs) have a significant issue for dental professionals. This study investigated the effects of high-frequency transcutaneous electrical nerve stimulation (TENS) on work-related pain, fatigue, and the active range of motion in dental professionals. Among recruited 47 dental professionals with WMSDs, 24 subjects received high-frequency TENS (the TENS group), while 23 subjects received placebo stimulation (the placebo group). TENS was applied to the muscle trigger points of the levator scapulae and upper trapezius, while placebo-TENS was administered without electrical stimulation during 60 min. Pain and fatigue at rest and during movement were assessed using the visual analog scale (VAS), pain pressure threshold (PPT), and active range of motion (AROM) of horizontal head rotation at six time points: prelabor, postlabor, post-TENS, and at 1 h, 3 h, and 1 day after TENS application. Both groups showed significantly increased pain and fatigue and decreased PPT and AROM after completing a work task. The TENS group showed significantly greater improvements in VAS score, fatigue, PPT, and AROM at post-TENS and at 1 h and 3 h after application (all P < 0.05) as compared to the placebo group. A single session high-frequency TENS may immediately reduce symptoms related to WMSDs in dental professionals.

Modern acupuncture-like stimulation methods: a literature review

Acupuncture therapy has been proved to be effective for diverse diseases, symptoms, and conditions in numerous clinical trials. The growing popularity of acupuncture therapy has triggered the development of modern acupuncture-like stimulation devices (ASDs), which are equivalent or superior to manual acupuncture with respect to safety, decreased risk of infection, and facilitation of clinical trials. Here, we aim to summarize the research on modern ASDs, with a focus on featured devices undergoing active research and their effectiveness and target symptoms, along with annual publication rates. We searched the popular electronic databases Medline, PubMed, the Cochrane Library, and Web of Science, and analyzed English-language studies on humans. Thereby, a total of 728 studies were identified, of which 195 studies met our inclusion criteria. Electrical stimulators were found to be the earliest and most widely studied devices (133 articles), followed by laser (44 articles), magnetic (16 articles), and ultrasound (2 articles) stimulators. A total of 114 studies used randomized controlled trials, and 109 studies reported therapeutic benefits. The majority of the studies (32%) focused on analgesia and pain-relief effects, followed by effects on brain activity (16%). All types of the reviewed ASDs were associated with increasing annual publication trends; specifically, the annual growth in publications regarding noninvasive stimulation methods was more rapid than that regarding invasive methods. Based on this observation, we anticipate that the noninvasive or minimally invasive ASDs will become more popular in acupuncture therapy.