The pain-evoked potential electroencephalogram (EEG) is an effective electrophysiological indicator for pain assessment, yet its extraction is challenging due to interference from background activity and involuntary blinks. Although existing blink artifact-removal methods show efficacy, they face limitations such as the need for reference signals, neglect of individual differences, and reliance on user input, hindering their practical application in clinical pain assessments. In this paper, we propose a novel framework applying adaptive quadrature mirror filter banks (AQMFB) with discrete wavelet transform (DWT) to remove blink artifacts in pain EEG. Unlike traditional DWT methods that apply fixed wavelets across subjects, our method adapts wavelet construction based on the characteristics of EEG. Experimental results demonstrate that AQMFB-DWT outperforms four leading methods in removing blink artifacts with minimal distortion of pain information, all within an acceptable processing time. This technique is a valuable preprocessing step for enhancing the extraction of pain-evoked potentials.
Humans ; Artifacts ; Blinking/physiology* ; Electroencephalography/methods* ; Pain/diagnosis* ; Male ; Wavelet Analysis ; Adult ; Female ; Evoked Potentials/physiology* ; Young Adult ; Brain/physiopathology* ; Pain Measurement/methods* ; Signal Processing, Computer-Assisted

Chronic pain, frequently comorbid with neuropsychiatric disorders, significantly impairs patients' quality of life and functional capacity. Accumulating evidence implicates the chemokine CCL2 and its receptor CCR2 as key players in chronic pain pathogenesis. This review examines the regulatory mechanisms of the CCL2/CCR2 axis in chronic pain processing at three hierarchical levels: (1) Peripheral Sensitization: CCL2/CCR2 modulates TRPV1, Nav1.8, and HCN2 channels to increase neuronal excitability and CGRP signaling and calcium-dependent exocytosis in peripheral nociceptors to transmit pain. (2) Spinal Cord Central Sensitization: CCL2/CCR2 contributes to NMDAR-dependent plasticity, glial activation, GABAergic disinhibition, and opioid receptor desensitization. (3) Supraspinal Central Networks: CCL2/CCR2 signaling axis mediates the comorbidity mechanisms of pain with anxiety and cognitive impairment within brain regions, including the ACC, CeA, NAc, and hippocampus, and it also increases pain sensitization through the descending facilitation system. Current CCL2/CCR2-targeted therapeutic strategies and their development status are discussed, highlighting novel avenues for chronic pain management.
Humans ; Chronic Pain/physiopathology* ; Animals ; Neuroglia/metabolism* ; Chemokine CCL2/metabolism* ; Receptors, CCR2/metabolism*

Temporomandibular joint osteoarthritis (TMJ-OA) is a common disease often accompanied by pain, seriously affecting physical and mental health of patients. Abnormal innervation at the osteochondral junction has been considered as a predominant origin of arthralgia, while the specific mechanism mediating pain remains unclear. To investigate the underlying mechanism of TMJ-OA pain, an abnormal joint loading model was used to induce TMJ-OA pain. We found that during the development of TMJ-OA, the increased innervation of sympathetic nerve of subchondral bone precedes that of sensory nerves. Furthermore, these two types of nerves are spatially closely associated. Additionally, it was discovered that activation of sympathetic neural signals promotes osteoarthritic pain in mice, whereas blocking these signals effectively alleviates pain. In vitro experiments also confirmed that norepinephrine released by sympathetic neurons promotes the activation and axonal growth of sensory neurons. Moreover, we also discovered that through releasing norepinephrine, regional sympathetic nerves of subchondral bone were found to regulate growth and activation of local sensory nerves synergistically with other pain regulators. This study identified the role of regional sympathetic nerves in mediating pain in TMJ-OA. It sheds light on a new mechanism of abnormal innervation at the osteochondral junction and the regional crosstalk between peripheral nerves, providing a potential target for treating TMJ-OA pain.
Animals ; Osteoarthritis/physiopathology* ; Mice ; Sympathetic Nervous System/physiopathology* ; Temporomandibular Joint Disorders/physiopathology* ; Arthralgia ; Sensory Receptor Cells ; Disease Models, Animal ; Norepinephrine ; Male ; Temporomandibular Joint/physiopathology* ; Pain Measurement

OBJECTIVE: To screen the population for acupuncture treatment of neck pain, using functional magnetic resonance imaging (fMRI) technology and based on machine learning algorithms. METHODS: Eighty patients with neck pain were recruited. Using FPX25 handheld pressure algometer, the tender points were detected in the areas with high-frequent onset of neck pain and high degree of acupoint sensitization. Acupuncture was delivered at 4 tender points with the lowest pain threshold, once every two days; and the treatment was given 3 times a week and for 2 consecutive weeks. The amplitude of low-frequency fluctuation (ALFF) of the brain before treatment was taken as a predictive feature to construct support vector machine (SVM), logistic regression (LR), and K-nearest neighbors (KNN) models to predict the responses of neck pain patients to acupuncture treatment. A longitudinal analysis of the ALFF features was performed before and after treatment to reveal the potential biological markers of the reactivity to the acupuncture therapy. RESULTS: The SVM model could successfully distinguish high responders (48 cases) and low responders (32 cases) to acupuncture treatment, and its accuracy rate reached 82.5%. Based on the SVM model, the ALFF values of 4 brain regions were identified as the consistent predictive features, including the right middle temporal gyrus, the right superior occipital gyrus, and the bilateral posterior cingulate gyrus. In the patients with high acupuncture response, the ALFF value in the left posterior cingulate gyrus decreased after treatment (P<0.05), whereas in the patients with low acupuncture response, the ALFF value in the right superior occipital gyrus increased after treatment (P<0.01). The longitudinal functional connectivity (FC) analysis found that compared with those before treatment, the high responders showed the enhanced FC after treatment between the left posterior cingulate gyrus and various regions, including the bilateral Crus1 of the cerebellum, the right insula, the bilateral angular gyrus, the left medial superior frontal gyrus, and the left middle cingulate gyrus (GRF: corrected, voxel level: P<0.05, mass level: P<0.05). In contrast, the low responders exhibited the enhanced FC between the left posterior cingulate gyrus and the left Crus2 of the cerebellum, the left middle temporal gyrus, the right posterior cingulate gyrus, and the left angular gyrus; besides, FC was reduced in low responders between the left posterior cingulate gyrus and the right supramarginal gyrus (GRF: corrected, voxel level: P<0.05, mass level: P<0.05). CONCLUSION This study validates the practicality of pre-treatment ALFF feature prediction for acupuncture efficacy on neck pain. The therapeutic effect of acupuncture on neck pain is potentially associated with its impact on the default mode network, and then, alter the pain perception and emotional regulation.
Humans ; Neck Pain/physiopathology* ; Acupuncture Therapy ; Female ; Male ; Adult ; Middle Aged ; Machine Learning ; Magnetic Resonance Imaging ; Young Adult ; Brain/physiopathology* ; Acupuncture Points ; Aged

OBJECTIVE: To explore the efficacy differences among different acupuncture frequencies for pain of temporomandibular disorders (TMD). METHODS: A total of 42 patients with TMD pain were randomly divided into a low-frequency group, a medium-frequency group, and a high-frequency group, with 14 patients in each group. All groups received acupuncture treatment at bilateral Hegu (LI4) and Yanglingquan (GB34), as well as ipsilateral Tinggong (SI19), Jiache (ST6), and Xiaguan (ST7), with each session lasting 30 minutes. The low-frequency group received acupuncture once per week, the medium-frequency group received acupuncture twice per week, and the high-frequency group received acupuncture three times per week, for a total duration of four weeks. The graded chronic pain scale (GCPS) score, visual analogue scale (VAS) score, jaw functional limitation scale-20 (JFLS-20) score, and pressure pain threshold (PPT) were assessed in the three groups before and after treatment, as well as at the four-week follow-up after treatment completion. RESULTS: Compared before treatment, GCPS and JFLS-20 scores were significantly decreased in all the groups after treatment (P<0.05), and VAS scores were significantly decreased in the high-frequency and medium-frequency groups (P<0.05), PPT values at different measurement sites were increased significantly in the high-frequency group (P<0.05). After treatment, GCPS, JFLS-20, and VAS scores in the high-frequency group were lower than those in the medium-frequency and low-frequency groups (P<0.05), while some PPT values were higher than the other two groups (P<0.05). At follow-up, GCPS, JFLS-20, and VAS scores remained significantly lower in all the groups compared to baseline (P<0.05), PPT values were increased significantly in the high-frequency and medium-frequency groups (P<0.05), with the high-frequency group showing lower GCPS, JFLS-20, and VAS scores and higher PPT values compared to the other two groups (P<0.05). CONCLUSION Acupuncture three times per week is more effective in reducing TMD pain intensity compared to once or twice per week, and can also alleviate some mandibular functional impairments. The therapeutic effects persist for at least four weeks after treatment completion.
Humans ; Male ; Female ; Adult ; Acupuncture Therapy/methods* ; Temporomandibular Joint Disorders/physiopathology* ; Middle Aged ; Young Adult ; Treatment Outcome ; Acupuncture Points ; Pain Management ; Adolescent ; Pain Measurement

OBJECTIVE: To compare the clinical efficacy of acupuncture with yin-yang regulation method versus local acupuncture in treating chronic low back pain (CLBP) in elderly patients with lumbar disc herniation (LDH), and to evaluate the changes in the multifidus muscle before and after treatment using musculoskeletal ultrasound. METHODS: A total of 128 elderly patients with CLBP due to LDH were randomly assigned to an observation group (64 cases, 2 cases dropped out) and a control group (64 cases, 2 cases dropped out). The control group received local acupuncture at bilateral L₃-L₅ Jiaji points (EX-B2), Shenshu (BL23), Dachangshu (BL25), Weizhong (BL40), Yaoyangguan (GV3), and ashi points. The observation group received acupuncture with yin-yang regulation method, which included an abdominal protocol with Baihui (GV20), Zhongwan (CV12), Qihai (CV6), Guanyuan (CV4), bilateral Tianshu (ST25), and Dahe (KI12), etc., and a lumbar protocol with Baihui (GV20), Dazhui (GV14), Jizhong (GV6), Yaoyangguan (GV3), and ashi points, etc., alternated bilaterally. Both groups were treated once every other day, three times per week, for a total of 12 sessions. The visual analogue scale (VAS) score, Oswestry disability index (ODI) score, and the indexs of musculoskeletal ultrasound multifidus muscle (resting and functional thickness and Young's modulus values) were observed before and after treatment, and the clinical efficacy was evaluated in the two groups. RESULTS: After 1 and 4 weeks of treatment, both groups showed lower VAS scores compared to baseline (P<0.05), the VAS scores in the observation group were lower than those in the control group (P<0.001). ODI scores in both groups were decreased after 1 and 4 weeks of treatment compared to baseline (P<0.05), with a further reduction at 4 weeks of treatment compared to 1 week of treatment (P<0.05); the observation group showed lower ODI score than the control group after 1 week of treatment (P<0.001). After treatment, both groups demonstrated increased resting and functional multifidus muscle thickness bilaterally compared to baseline (P<0.01), with an increased right-side thickness change rate (P<0.01), though no significant difference was observed between groups (P>0.05). Compared to baseline, after treatment, the observation group exhibited decreased Young's modulus values for bilateral resting and functional multifidus muscle (P<0.01), while the control group showed reductions only in bilateral resting and right-side functional Young's modulus values (P<0.01). After treatment, the bilateral functional Young's modulus values in the observation group were lower than that in the control group (P<0.05), and the bilateral resting and functional changes in Young's modulus values were greater in the observation group than those in the control group (P<0.01). The overall effective rate was 93.5% (58/62) in the observation group, which was higher than 79.0% (49/62) in the control group (P<0.05). CONCLUSION Acupuncture with yin-yang regulation method effectively alleviates pain, improves functional disability, increases multifidus muscle thickness, and reduces Young's modulus values in elderly patients with CLBP due to LDH, which has superior therapeutic effect compared to local acupuncture.
Humans ; Low Back Pain/physiopathology* ; Male ; Acupuncture Therapy ; Female ; Aged ; Intervertebral Disc Displacement/physiopathology* ; Middle Aged ; Yin-Yang ; Lumbar Vertebrae ; Acupuncture Points ; Treatment Outcome

OBJECTIVE: To observe the clinical effect of Fu's subcutaneous needling based on anatomy train theory for nonspecific low back pain (NLBP). METHODS: A total of 120 patients with NLBP were randomized into an anatomy train Fu's subcutaneous needling group (40 cases, 3 cases dropped out), a conventional acupuncture group (40 cases, 2 cases dropped out) and a conventional Fu's subcutaneous needling group (40 cases, 2 cases dropped out). Acupuncture was applied at ashi points and bilateral Shenshu (BL23) and Dachangshu (BL25) in the conventional acupuncture group, once every other day, 3 times a week. Fu's subcutaneous needling was applied at lumbodorsal myofascial trigger points (MTrPs) in the Fu's subcutaneous needling group, once every 3 days, twice a week. On the basis of the treatment in the Fu's subcutaneous needling group, Fu's subcutaneous needling was applied at MTrPs along the posterior superficial line and lateral line in the anatomy train Fu's subcutaneous needling group, once every 3 days, twice a week. All groups were treated for 2 weeks. Before and after treatment, the scores of numeric rating scale (NRS) and Oswestry disability index (ODI) were observed, the distance of Schober test was measured and the endurance of trunk extensors was assessed in the 3 groups. RESULTS: After treatment, in the 3 groups, the NRS and ODI scores were decreased compared with those before treatment (P<0.05), the Schober test distance was increased compared with that before treatment (P<0.05), the static and dynamic muscle endurance was increased compared with that before treatment (P<0.05). After treatment, in the anatomy train Fu's subcutaneous needling group, the NRS and ODI scores were lower than those in the conventional acupuncture group and the conventional Fu's subcutaneous needling group (P<0.05), the Schober test distance was longer than that in the conventional acupuncture group and the conventional Fu's subcutaneous needling group (P<0.05), the static and dynamic muscle endurance was superior to that in the conventional acupuncture group and the conventional Fu's subcutaneous needling group (P<0.05). CONCLUSION Fu's subcutaneous needling based on anatomy train theory can effectively relieve the pain symptom, enhance quality of life, improve lumbar motion and lumbar muscle function in patients with NLBP.
Humans ; Low Back Pain/physiopathology* ; Female ; Male ; Adult ; Acupuncture Therapy/methods* ; Middle Aged ; Acupuncture Points ; Young Adult ; Treatment Outcome ; Aged

OBJECTIVE: To explore the pain-location interaction between pressure-sensitive points on the body surface and traditional acupoints in patients with chronic non-specific low back pain (CNLBP) under different disease courses, using Euclidean distance and multivariate statistical analysis. METHODS: A pressure-sensitive point detection was performed on 30 CNLBP patients with varying disease courses. A constant pressure was applied using an FDK20 algometer within a designated lumbar area, a total of 50 points were tested, and the tested points were numbered; the visual analogue scale (VAS) pain score was recorded simultaneously. MatlabR2022a9.12. software was used to extract the positions of pressure-sensitive points, and preprocessing and normalization of point location and VAS scores data were conducted. Under constraint conditions (VAS≥8.0 ∩ Euclidean distance to acupoint≤0.5), the proportion of pressure-sensitive points within the Euclidean distance threshold to each acupoint (PVD_acupoint) was calculated, followed by multivariate statistical analysis. RESULTS: ①Constrained analysis of PVD_acupoint showed that PVD_{Qihaishu (BL24)} and PVD_{Dachangshu (BL25)} were positively correlated with disease course (r=0.55, P<0.01). ②Factor analysis and silhouette analysis revealed that PVD_{Shenshu (BL23)} and PVD_{Dachangshu (BL25)} exhibited trends consistent with disease course progression (P>0.05), with different degree (P<0.01). CONCLUSION The PVD_acupoint value based on Euclidean distance can characterize the pressure sensitivity features of traditional acupoints associated with disease. Multivariate statistical analysis of PVD_acupoint confirms that selecting the acupoint combination of Shenshu (BL23) and Dachangshu (BL25) for CNLBP is associated with the distribution of surrounding pressure-sensitive points and the pathological characteristics of the condition.
Humans ; Acupuncture Points ; Low Back Pain/physiopathology* ; Male ; Female ; Middle Aged ; Adult ; Aged ; Acupuncture Therapy ; Young Adult ; Pressure

Endothelin-1 is a peptide derived from endothelial cells, consisting of 21 amino acid residues. In recent years, research has found that endothelin-1 not only plays a key role in vascular tone regulation but also participates in the occurrence and development of various types of pathological pain, including inflammatory pain, neuropathic pain, and cancer pain. Endothelin-1 binds to its receptors and activates multiple signaling pathways such as protein kinase C, calcium ion channels, and the phosphoinositide pathway, thereby influencing neuronal excitability and nociceptive information transmission. This article briefly reviews the current understanding of the mechanisms and potential roles of endothelin-1 in the development of pain, as well as commonly used endothelin-1 receptor antagonists, aiming to provide clues for better utilizing endothelin-1 and its receptors to alleviate and treat pathological pain.
Humans ; Endothelin-1/physiology* ; Pain/physiopathology* ; Signal Transduction/physiology* ; Animals ; Neuralgia/physiopathology* ; Cancer Pain/physiopathology* ; Endothelin Receptor Antagonists

OBJECTIVE: To investigate the effectiveness and safety of simultaneous bilateral total knee athroplasty (SB-TKA) for the treatment of patients aged 65 years and younger with bilateral knee osteoarthritis (KOA) by comparing with patients undergoing unilateral total knee arthroplasty (U-TKA). METHODS: A clinical data of patients, who underwent primary TKA for KOA and met the selection criteria between June 2019 and July 2023, was retrospectively analyzed, including 181 patients in the U-TKA group and 52 patients in the SB-TKA group. The baseline data of age, gender, disease duration, body mass index, and preoperative hemoglobin (Hb), knee range of motion (ROM), Oxford knee score (OKS), and visual analogue scale (VAS) score for pain were compared between the two groups, with no significant difference ( P>0.05). The operation time, postoperative hospital stay, and all complications related to knee arthroplasty were recorded. Hb was measured at 2 days after operation and the difference between pre- and post-operation was calculated. The knee function and pain were evaluated by using ROM, OKS score, and VAS score and compared between the two groups. RESULTS: The operation time and postoperative hospital stay duration were significantly shorter in the U-TKA group than in the SB-TKA group ( P<0.05). The difference of Hb was significantly lower in the U-TKA group ( P<0.05). All patients were followed up 12-61 months (mean, 37.2 months). There was no significant difference in follow-up time between the two groups ( P>0.05). At last follow-up, the ROM, OKS score, and VAS score of both groups were better than the preoperative ones, and the differences were significant ( P<0.05); there were significant differences between the two groups in the ROM and OKS score ( P<0.05), while no significant difference was found in the VAS score ( P>0.05). Mild complications were observed in 31 cases (17.13%) and severe complications in 3 cases (1.66%) in the U-TKA group, while mild complications were observed in 14 cases (26.92%) in the SB-TKA group, and no severe complication occurred. There was no significant difference in the incidences of mild and severe complications between the two groups ( P>0.05). CONCLUSION In patients aged 65 years and younger with bilateral KOA, knee function and mobility can significantly improved when treated by SB-TKA. While patients had lower postoperative knee mobility and function scores compared with U-TKA, there was no significant difference in pain scores or overall incidence of complication. Strict patient selection and scientific perioperative management are important to achieve good effectiveness after operation in patients with SB-TKA.
Humans ; Arthroplasty, Replacement, Knee/adverse effects* ; Male ; Female ; Retrospective Studies ; Osteoarthritis, Knee/physiopathology* ; Range of Motion, Articular ; Treatment Outcome ; Middle Aged ; Operative Time ; Length of Stay ; Knee Joint/physiopathology* ; Pain Measurement ; Postoperative Complications/epidemiology* ; Aged