Different patterns of blood flow response in the trapezius muscle following needle stimulation (acupuncture) between healthy subjects and patients with fibromyalgia and work-related trapezius myalgia

Stimuli-evoked NOergic molecules and neuropeptides at acupuncture points and the gracile nucleus contribute to signal transduction of propagated sensation along the meridian through the dorsal medulla-thalamic pathways

Numerous studies from different international groups have demonstrated that sensations can be propagated along acupuncture channel pathways. The propagated sensation along the channel pathway (PSCP) can be elicited by electroacupuncture (EA), transcutaneous electrical nerve stimulation (TENS), manual acupuncture (MA), and heat applied to distal acupuncture points (acupoints). Nitric oxide (NO) levels were reported to be elevated in the gracile nucleus and skin regions near to the EA sites, with higher levels at acupoints associated with an enhanced expression of NO synthase and transient receptor potential vanilloid type 1. The stimuli, EA, MA, TENS, and heat, have been used to elicit axonal reflexes, which increase local release of NO and neuropeptides such as calcitonin gene related peptide. Furthermore, the sensation of PSCP along the body surface occurs only ipsilaterally to the stimulated acupoints in various human studies, which does not support the involvement of the spinal-thalamic pathway, which would involve cross over transmission of the signals. The gracile nucleus receives ascending input from the sciatic nerve and responds to somatosensory stimulation mainly on the ipsilateral side via the dorsal column pathway. EA at Zusanli (ST36) increases NO release and expression of NO synthase mainly in the ipsilateral side of the gracile nucleus, while the cardiovascular effects and analgesic responses to EA at ST36 are changed by influences of l-arginine-derived NO synthesis in the ipsilateral gracile nucleus in rats. The stimuli-induced release of NOergic molecules and neuropeptides exist high levels in the acupoints, which contain rich neuronal components and blood vessels. Enhanced NOergic molecules at acupoints cause axon reflexes during the stimuli, which elevate cutaneous blood flow. Elevated NOergic molecules and local blood flow may spread over acupoints one after another along the meridian lines differing from nerve pathways following the stimuli to induce PSCP. The same types of stimulation also elicit NO release in the gracile nucleus, which contributes to the somatosensory signal transduction of PSCP through the dorsal medulla-thalamic pathways. Other substances such as serotonin and catecholamines are proposed to mediate responses and certain effects of acupuncture-like stimulation but their mechanisms are poorly-understood. In this review we summarize the current understanding of the neurobiological processes of PSCP research with an emphasis on recent developments of NO mediating stimulation-evoked axon reflexes and somatosensory signal transduction for PSCP perceptions through the dorsal medulla-thalamic pathways. Please cite this article as: Ma SX. Stimuli-evoked NOergic molecules and neuropeptides at acupuncture points and gracile nucleus contribute to signal transduction of propagated sensation along the meridian through the dorsal medulla-thalamic pathways. J Integr Med. 2024; 22(5): 515-522.

Biomechanical Profile after Dry Needling in Mixed Martial Arts

The purpose of this study was to compare the effects of dry needling (DN) intervention on the responses of muscle tone, stiffness, and elasticity, as well as power, pressure pain thresholds, and blood perfusion of the flexor carpi radialis muscle in mixed martial arts (MMA) athletes. Thirty-two trained/developmental men MMA fighters (25.5±4.5 years; 24.5±3 body mass index) participated in a randomized crossover study. Participants underwent a single intervention, receiving both DN and placebo. Laser Doppler flowmetry measured blood perfusion, while a myotonometer assessed the mechanical characteristics of muscle tone, stiffness, and elasticity of the flexor carpi radialis muscle. Pressure pain thresholds (PPT) were measured using an algometer, and maximal forearm muscle force was measured using a hand dynamometer. Outcomes were assessed at baseline, immediately after, and 24 hours and 48 hours post-intervention. A two-way repeated-measures ANOVA revealed significant Intervention*Time interaction for all outcomes: perfusion unit (p<0.001), muscle tone (p<0.001), stiffness (p<0.001), elasticity (p<0.001), PPT (p<0.001) and maximal forearm muscle force (p<0.001). The current study suggests that a single session of DN enhances muscle recovery, increases muscle strength, and improved PPT in MMA athletes. These positive adaptations appear to last up to 48 hours in some variables.

Acute Effects of the Dry Needling Session on Gastrocnemius Muscle Biomechanical Properties, and Perfusion with Latent Trigger Points - A Single-Blind Randomized Controlled Trial in Mixed Martial Arts Athletes

The study aimed to evaluate the immediate effects of a dry needling (DN) therapy session on biomechanical properties, muscle power, perfusion, and pressure pain threshold of the gastrocnemius muscle with latent trigger points. Twenty mixed martial arts athletes (MMA) were randomly divided into two groups: experimental (eDN, n = 10) and sham (qDN, n = 10) to undergo one session of DN either with a real or a qazi needle. The measurements were taken at rest, 1-5 minutes after the DN (Post1-5min) and 24h after the DN (Post24h). DN significantly increased the muscle perfusion (Post1-5min and Post24h, p < 0.001), reduced its tone (Post1-5min and Post24h, p < 0.001) and stiffness (Post1-5min, p < 0.05; Post24 h, p < 0.001), and improved its elasticity (Post1-5min and Post24h, p < 0.001). DN also caused a significant increase in pressure pain threshold (Post1-5min, p < 0.001; Post24h, p < 0.05) and in muscle power (Post24h, p < 0.01). The DN session increased the blood perfusion and improved the biomechanical properties of the gastrocnemius muscle, which led to improved muscle power. The DN also had an analgesic effect. These effects were maintained at 24 h, which suggests that DN could facilitate muscle recovery in a post-exercise period of MMA athletes.

Trigger point dry needling increases masseter muscle oxygenation in patients with temporomandibular disorder

BACKGROUND

Temporomandibular disorder (TMD) is an umbrella term encompassing various clinical complaints involving the temporomandibular joints, masticatory muscles, and/or associated orofacial structures. Myogenous TMDs are the most frequent cause of chronic orofacial pain. Musculoskeletal pain is commonly associated with myofascial trigger points (MTPs), for which dry needling (DN) is a routine treatment.

OBJECTIVE

To investigate muscle oxygenation and pain immediately after DN application on an MTP in the masseter muscle of patients with myogenous TMDs.

METHODOLOGY

Masseter muscle oxygen tissue saturation indices (TSI%) were assessed by near-infrared spectroscopy (NIRS) pre- and post-interventions by a randomized, controlled, double-blind, crossover DN/Sham clinical trial (primary outcome). Pain was investigated by the visual analog scale (VAS). In total, 32 individuals aged from 18 to 37 years who were diagnosed with myogenous TMD and myofascial trigger points in their masseter muscles participated in this study. Relative deltas for the studied variables were calculated. Data normality was tested using the Shapiro-Wilk test. According to their distribution, data were analyzed by two-way ANOVA and the Student's t-, and Mann-Whitney tests. Statistical analyses were performed using Prism® 5.0 (GraphPad, USA).

RESULTS

We found a significant difference (2,108% vs. 0,142%) between masseter muscle TSI% deltas after the DN and Sham interventions, respectively (n=24). We only evaluated women since men refused to follow NIRS procedures. Pain increased immediately after DN (n=32, 8 men), in comparison to Sham delta VAS.

CONCLUSION

These findings show an increase in tissue oxygen saturation in the evaluated sample immediately after the DN intervention on the MTP of patients' masseter muscle. Pain may have increased immediately after DN due to the needling procedure.

Can Acupuncture Improve the Flexibility of Hamstring Muscles? A Randomized, Blinded, and Controlled Pilot Study

(1) Background: The lack of flexibility is frequently reported as a risk factor for hamstring muscle damage. Acupuncture, a therapeutic tool of traditional Chinese medicine (TCM), may play a role in both treatment and prevention by improving muscle strength, microcirculation, and reducing muscle soreness. The primary objective of this pilot study was to examine the immediate effects of acupuncture on hamstring muscle stretching and on the pain or discomfort reported during stretching. (2) Methods: To mitigate heterogeneity effects, and due to the small sample size, the study employed a crossover design in which each participant was tested at three different moments of the experimental period with verum (true acupuncture in selected acupoints), sham (fake acupuncture in zones of the skin not corresponding to any known acupoint but near the selected acupoints), and placebo (stimulation of the selected acupoints with a stainless steel wire and cannula, without puncturing) stimulations. Flexibility and pain or discomfort were assessed using the seat and reach test (SR) and a visual analogic scale (VAS). (3) Results: Significant changes in flexibility were observed after verum acupuncture (p = 0.03), while no significant changes were seen in sham and placebo (p = 0.86 and p = 0.18, respectively). No significant differences were found in pain or discomfort during any of the stimulations (verum, p = 0.55; sham, p = 0.50; placebo, p = 0.58). (4) Conclusions: The results of this pilot study suggest that acupuncture may improve flexibility in the hamstring muscles, though it does not significantly affect pain or discomfort during stretching.

Application of Acupuncture for Shoulder Pain Over the Past 22 Years: A Bibliometric Analysis

Purpose

Acupuncture is widely used to relieve shoulder pain. A survey was conducted in order to recognize hotspots and frontiers of acupuncture for shoulder pain from the year 2000-2022.

Methods

The Web of Science Core Collection was used to collect literature related to acupuncture therapy for shoulder pain, which spanned January 2000 to August 2022. The number of publications yearly, countries/institutions, journals, and keywords was analyzed and visualized in shoulder pain with acupuncture therapy by CiteSpace v.5.7.R5.

Results

We totally analyzed 214 articles that met the inclusion criteria. The overall trend of publication volume continues to increase. The most productive authors in the field were César Fernández las Peñas and José L Arias-Buría, and the most influential author was Green S. Kyung Hee University and the People's Republic of China had the highest volume of publications, respectively. The most influential journal is Pain with high citation and impact factor. The hot keywords were "acupuncture", "shoulder pain", "dry needling", "randomized trial", and "injection". The research frontier in acupuncture for treating chronic shoulder pain was mainly "mechanism".

Conclusion

Over the last 22 years, the findings of this bibliometric analysis have provided research trends and frontiers in clinical research on acupuncture therapy for patients with shoulder pain, which identifying hot topics and exploring new directions for the future may be helpful to researchers. Studying mechanisms underlying acupuncture therapy for shoulder pain remains a focus of future research.

Ultrasound-guided dry needling versus traditional dry needling for patients with knee osteoarthritis: A double-blind randomized controlled trial

Objective

To compare the effect of ultrasound (US)-guided dry needling (DN) with traditional DN in the treatment of pain and dysfunction for patients with knee osteoarthritis (KOA).

Design

A double-blind, randomized controlled trial.

Methods

Patients (25 male and 65 female), age 50–80 years diagnosed with KOA were recruited and randomly assigned to one of three groups in a 1:1:1 ratio for intervention: real US-guided DN with exercise therapy (G1), placebo US-guided DN with exercise therapy (G2), and exercise therapy solely (G3). G1 and G2 were blinded to the application of real or placebo US guidance by turning the monitor of US imaging out-of-view from participants’ vantage points. The effectiveness of blinding was evaluated by asking the participants whether they had received real-US guided DN. The responses were assessed by Chi-square test. Visual Analogue Scale (VAS), Knee injury, and Osteoarthritis Outcome Score (KOOS) subscales (KOOS-pain, KOOS-symptoms, KOOS-quality-of-life (QoL)) were collected at baseline, 4 weeks, and 8 weeks by a blinded assessor. Data were analyzed by mixed model analysis of variance (ANOVA) with Bonferroni correction.

Results

Eighty-four participants (61.26±5.57 years) completed the study. G1 achieved significant improvement in VAS at 8 weeks compared to G2 and G3 (G1 vs. G2: MD = -15.61, 95% CI [-25.49, -5.51], p = 0.001; G1 vs. G3: MD = -19.90, 95% CI [-29.71, -10.08], p< 0.001). G1 achieved significant improvement in KOOS-pain at 8 weeks compared to G2 and G3 (G1 vs. G2: MD = 9.76, 95% CI [2.38, 17.14], p = 0.006; G1 vs. G3: MD = 9.48, 95% CI [2.31, 16.66], p = 0.010). KOOS-symptoms and KOOS-QoL were not statistically significant between groups. G2 had no significant difference of the perceptions as G1 with p = 0.128. G2 were successfully blinded to placebo US-guided DN.

Conclusion

US-guided DN with exercise therapy may be more effective than traditional DN with exercise therapy or exercise therapy alone in reduce pain of KOA.

Knowledge Mapping of Acupuncture for Fibromyalgia from 1990 to 2022: A Bibliometric Analysis

Background

Fibromyalgia is a rheumatic disease with no specific laboratory markers and is insensitive to hormonal drugs and nonsteroidal anti-inflammatory drugs commonly used to treat rheumatism. Guidelines recommend that non-pharmacological therapy should be the first-line treatment for fibromyalgia. Since the publication of the first diagnostic criteria for fibromyalgia in 1990, studies on acupuncture for fibromyalgia have been reported periodically. This study aims to explore the intellectual landscape of acupuncture for fibromyalgia since 1990, and to identify research trends and fronts in this field.

Methods

The Web of Science Core Collection Database was searched for publications on acupuncture for fibromyalgia from 1990 to 2022. VOSviewer and CiteSpace were used to analyze the annual publication, countries, institutions, authors and cited authors, journals and cited journals, references and keywords.

Results

A total of 280 publications were retrieved, and the number of publications showed an overall upward trend. The United States was the most productive country. China Medical University was the institution with the most publications. Lin Yi-wen was the most prolific author, while Wolfe was the most cited author. Evidence-Based Complementary and Alternative Medicine was the journal in which most of the research was published, while Pain was the most cited journal. An article by Wolfe (1990) had the most citations, but an article by Crofford (2001) had the highest centrality. The four most frequently used keywords in the included articles were mechanism, spinal cord, activation and sensitivity.

Conclusion

Acupuncture can effectively relieve pain in patients with fibromyalgia and improve accompanying symptoms such as anxiety and depression. However, the design of clinical trials still needs to be optimized to better verify the efficacy of acupuncture on various clinical symptoms of fibromyalgia. Exploring the central analgesic mechanism of acupuncture on fibromyalgia is also the focus research direction now and future.

Not just sensitization: sympathetic mechanisms contribute to expand experimental referred pain

Background

Widespread pain partially depends upon sensitization of central pain mechanisms. However, mechanisms controlling pain distribution are not completely known. The present study sought to assess skin temperature variations in the area of experimentally-induced pain and potential sex differences.

Methods

Pressure-pain thresholds (PPTs) were measured on the right infraspinatus muscle. At the end of Day 0, all participants performed an eccentric exercise of the shoulder external rotators to induce muscle soreness 24 hours after. On Day 1, participants indicated on a body chart the area of pain induced by 60 seconds of suprathreshold pressure stimulation (STPS; PPT + 20%) on the right infraspinatus muscle. Skin temperature variations in the area of referred pain were recorded with an infrared thermography camera, immediately before and after the STPS.

Results

Twenty healthy, pain-free individuals (10 females) participated. On Day 0, the pre-STPS temperature was higher than the post-STPS temperature on the arm (P = 0.001) and forearm (P = 0.003). On Day 1, the pre-STPS temperature was higher than the post-STPS temperature on the shoulder (P = 0.015), arm (P = 0.001), and forearm (P = 0.010). On Day 0, the temperature decrease after STPS in females was greater than in males on the forearm (P = 0.039). On Day 1, a greater temperature decrease was found amongst females compared with males at the shoulder (P = 0.018), arm (P = 0.046), and forearm (P = 0.005).

Conclusions

These findings indicate that sympathetic vasomotor responses contribute to expand pressure-induced referred pain, especially among females.

Influence of Acupuncture on Microcirculation Perfusion of Pericardium Meridian and Heart in Acute Myocardial Ischemia Model Rats

OBJECTIVE

To observe the influence of acupuncture on microcirculation perfusion of the pericardium meridian and heart in acute myocardial ischemia (AMI) rats and evaluate whether acupuncture can simultaneously affect the meridians and corresponding viscera. Additionally, acupoints at different meridians were compared and whether they exert the same effects was discussed.

METHODS

Totally 32 Sprague-Dawley rats were subjected to left anterior descending (LAD) ligation to develop an AMI model. Rats were divided into 4 groups, including AMI, acupuncture Neiguan (PC 6), Lieque (LU 7) and Qiansanli (LI 10) groups (n=8). Eight rats received only thoracotomy (sham-operated group). The rats in the acupuncture groups received manual acupuncture at PC 6, LU 7 and LI 10 acupoints for 15 min, respectively. The microcirculation perfusion of pericardium meridian and heart was monitored by laser speckle perfusion imager (LSPI) before, during and after acupuncture manipulation for 15 min. Subsequently, the perfusion unit (PU) was calculated and analyzed by PSI System.

RESULTS

After LAD, compared to pre-acupuncture stage, the heart microcirculation perfusion (HMP) in the AMI group decreased continuously at during-acupuncture (P>0.05) and post-acupuncture stages (P<0.05), and the pericardium meridian microcirculation perfusion (PMP) showed no significant differences at 3 stages (P>0.05). Compared to pre-acupuncture stage, the PMP and HMP in PC 6 group significantly increased during acupuncture manipulation (both P<0.05), and PMP decreased obviously after acupuncture (P<0.05). The PMP in the LU 7 and LI 10 groups were slightly elevated (both P>0.05); however, they were significantly reduced after acupuncture manipulation (both P<0.05). Additionally, HMP of LI 10 group was decreased significantly during acupuncture, especially compared to pre-acupuncture stage (P<0.05).

CONCLUSIONS

Acupuncture at PC 6 obviously increased the PMP and HMP in AMI rats, and the effects were superior to at LU 7 and LI 10 acupoints. It was further confirmed that acupuncture promoted qi and blood circulation, indicating that acupoint specificity exists and features a meridian-propagated effect.

Analysis and comparison of pain pressure threshold and active cervical range of motion after superficial and deep dry needling techniques of the upper trapezius muscle

OBJECTIVES

To evaluate the changes in pain pressure threshold (PPT) and active cervical range of motion (ACROM) after the application of superficial dry needling (DN) or deep DN in myofascial trigger point (MTrP) 1 of the upper trapezius versus a simulated DN technique in the gastrocnemius muscle (control group).

DESIGN

Double-blind, randomized controlled trial with 7-day follow-up.

PARTICIPANTS

Asymptomatic volunteers (n = 180; 76 men, 104 women) with a latent MTrP 1 in the upper trapezius were randomly divided into three groups: G1, receiving superficial DN in the upper trapezius; G2, receiving deep DN in the upper trapezius; and G3, control group, receiving simulated DN technique in the gastrocnemius muscle.

MAIN OUTCOME MEASURES

While sitting in a chair, each subject underwent measurements of PPT and ACROM (ipsilateral and contralateral side flexion and rotation, flexion and extension) preintervention, (immediately) postintervention, and at 24 h, 72 h and 7 days.

RESULTS

Superficial and deep DN produced an increase in PPT at 7 days with respect to preintervention levels. Furthermore, superficial and deep DN produced a decrease in cervical flexion at 24 h and an increase in ipsilateral rotation until 72 h, increasing to 7 days in the case of deep DN. On the contrary, superficial DN produced an increase in ipsilateral and contralateral side flexion after intervention, unlike deep DN that produced a decrease at 24 h. Furthermore, superficial DN produced an increase in contralateral rotation at 24 h and deep DN decreased extension at 72 h.

CONCLUSION

A single intervention of superficial or deep DN did not produce statistically significant changes in PPT or goniometry measurements.Trial registration number: NCT03719352 (ClinicalTrials.gov).

The effects of dry needling on pain relief and functional balance in patients with sub-chronic low back pain

BACKGROUND

Pain relief is important both for the movement of patients suffering from low back pain and the quality of life. Dry needling is effective on myofascial trigger points but its effect on the area of pain and the functional balance is not fully known.

OBJECTIVE

To examine the immediate effect of dry needling on pain and functional balance of patients suffering from low back pain.

METHODS

Twenty five patients with sub-chronic low back pain were randomly divided into two groups: the intervention or control group. Needles were used for the participants of the intervention group, bilaterally at the spinus level, one and a half finger breath from the midline in levels L2-L5 of the lumbar spine. A third line of needles was inserted in the interspinosus spaces, except L5-S1 level. Bipedal stance, lateral loading and mediolateral body sway were assessed using a pair of force plates. Pain tolerance was assessed using an algometer.

RESULTS

The pain tolerance significantly increased in the intervention group from (M = 4.87, SE 0.663) to (M = 6.52, SE 0.547) (F(1,23) = 7.8, p< 0.05) after intervention. During mediolateral body sway the force signal in the dominant frequency significantly increased in the intervention group from (M = 43.2, SE 4.6) to (M = 54,9, SE 3.6) (F(1,23) = 4.63, p< 0.05) after intervention, exhibiting more controlled rhythmic behavior.

CONCLUSIONS

Dry needling in painful areas and penetrating all the muscle groups seems to improve pain and functional balance, yet its effect on specific muscles needs to be studied further.

Acute Effects of Dry Needling on Myofascial Trigger Points in the Triceps Surae of Ballet Dancers: A Pilot Randomized Controlled Trial

BACKGROUND

There is convincing evidence that dancers suffer injuries to the triceps surae musculature. Research on the immediate effects of dry needling (DN) is limited, and it is important to understand the acute effects of this treatment prior to performance.

PURPOSE

The purpose of this pilot study was to assess the immediate effects of DN on myofascial trigger points in terms of skin surface temperature, pain, active and passive range of motion, and torque production in the triceps surae of ballet dancers.

STUDY DESIGN

Randomized, double-blinded pilot study.

METHODS

Professional ballet dancers that fit inclusion and exclusion criteria (n=11) were randomly assigned to an experimental or control group. The dancers had three pre-determined standard point (SP) measurement spots that were used as a baseline for surface temperature comparisons. The dancers were also palpated for trigger point (TP) spots. Both SP and TP spots were marked for future measurements. The experimental group received DN, while the control group received sham DN (SHAM) to their bilateral calves at the TP spots. Immediately prior to and following treatment, both DN and SHAM groups were tested for skin surface temperature, pain, range of motion, and plantar flexion torque by blinded assessors. Paired t-tests and independent t-tests were performed to examine for differences between groups.

RESULTS

The surface temperature for the TP was higher than the SP measurements prior to intervention (Right calf p= .014; Left calf p= .031). There were no significant changes in VAS scale reported pain and ROM. The plantar flexion torque measurements showed an increase in the DN group of the left calf at the angular velocity of 60 degrees/sec.

CONCLUSION

This was a unique pilot study examining the acute effects of DN on professional ballet dancers. The results were limited due to low sample size. However, the methodology for this study and surface temperature results invites future research.

LEVEL OF EVIDENCE

Level 1b.

Application of traditional Chinese therapy in sports medicine

Chinese herbs have been used as dietary supplements to improve exercise performance. However, evidence-based studies for the use of Chinese herbs in sports remain scarce. Traditional Chinese therapy (TCT), a form of traditional Chinese non-pharmacological intervention, has remained in use for thousands of years in sports medicine. TCT is beneficial for sports injuries and in enhancing skill development, and is becoming increasingly popular among athletes, fitness enthusiasts, and individuals who regularly exercise. The therapeutic effects of TCT have been demonstrated by clinical and experimental studies, but using these modalities still is associate with potentially adverse effects. Further well-designed studies are necessary to confirm the efficacy of TCT in sports medicine. This review aims to summarize the application of TCT, discuss the issues surrounding TCT clinical research, and provide suggestions for applying traditional Chinese methods in the field of sports medicine.

Effects of Manual Acupuncture with Sparrow Pecking on Muscle Blood Flow of Normal and Denervated Hindlimb in Rats

Introduction

In clinical practice, it has been thought that acupuncture might serve to wash out pain-generating metabolic end-products by improving blood circulation in muscles. We investigated the effects of manual acupuncture (MA) on muscle blood flow (MBF) of normal and denervated hindlimbs in rats.

Method

Sprague-Dawley rats (n=100) anaesthetised with urethane (1.2g/kg ip) were used. Manual acupuncture with sparrow pecking (SP) at different doses (1, 10 or 30 pecks) was given to the right ventral hindlimb muscles (tibial anterior and extensor digitorum longus muscles) or the right dorsal hindlimb muscles (gastrocnemius, plantaris and soleus muscles). MBF with or without MA was measured using the radiolabelled microsphere technique. The blood pressure was recorded through the right common carotid artery until MBF measurement started. Denervation of hindlimb was conducted by cutting the sciatic and femoral nerves.

Results

In normal rats, significantly increased MBF after MA were observed only in muscles which were penetrated by an acupuncture needle. The size of the increase depended on the number of times of pecking and seemed to be sustained at least until 60 minutes after MA. However, the increase was observed after both acute and chronic denervation. On the other hand, the mean arterial blood pressure (MAP) did not change significantly before, during or after MA.

Conclusion

These results suggest that MA could increase muscle blood flow locally in a dose-dependent manner and that this increase may be caused by local vasodilators, as well as the axon reflex. A further study is needed to elucidate the mechanism.

The Effects of Electrical Acupuncture and Essential Amino Acid Supplementation on Sarcopenic Obesity in Male Older Adults: A Randomized Control Study

OBJECTIVE

Aging which is accompanied by loss of skeletal muscle and increase of body fat in some adults older than 60 years does not only result in remarkable influences on daily life function but also increases the risk of cardiovascular events. This study used electrical acupuncture together with essential amino acid supplementation to treat sarcopenic obesity (SO) in male older adults.

METHODS

A total of 48 male participants with SO (>60 years old) were randomized to electrical acupuncture with oral essential amino acids (EA + AA) or oral essential amino acids alone (AA). Acupuncture points on the limbs were punctured and stimulated electrically once every 3 days for 12 weeks. All participants received essential amino acids orally, twice per day for 28 weeks. Body fat percentage (BFP) and appendicular skeletal muscle index (ASM/H2) was determined by bioelectrical impedance analysis.

RESULTS

Both groups exhibited significant changes in BFP after 12, 20, and 28 weeks compared with baseline values; for ASM/H2, there were significant differences to baseline values after 12, 20, and 28 weeks in the EA + AA group, but only after 28 weeks in the AA group. Between the two groups, there were significant differences in BFP after 12, 20, and 28 weeks, and in ASM/H2 after 20 and 28 weeks.

CONCLUSION

Both methods decrease BFP and increase ASM/H2. In male older adults, electrical acupuncture with oral essential amino acids is more effective and can increase muscle mass in a shorter time than oral essential amino acids alone.

Nitric oxide signaling molecules in acupoints: Toward mechanisms of acupuncture

Recent clinical trial studies have demonstrated that the effects of acupuncture on pain improvement are small and no difference between acupoints and non-points. Whether acupuncture needles must be inserted in specific points depends on whether acupoint specificity exists that is still not resolved, and is now urgent. Previous anatomical studies have demonstrated that acupoints exist higher number of nerve fibers/trunks, blood vessels, hair follicles, and sweat glands as well as density of the gap junction. Recent evidence shows that nitric oxide (NO) level is elevated in the acupoints/ meridians and is associated with an enhanced expression of NO synthase endowed with transient receptor potential vanilloid type-1. There is growing evidence from international groups showing that acupuncture induces NO-mediated vasodilatation, which increases local blood flow and allows for a flush of algesic or sensitizing substances, leading to pain relief. Previous studies, using a novel biocapture system, have demonstrated that NOx- (total nitrite and nitrate) and cyclic guanosine monophosphate (cGMP) concentrations are consistently increased over skin acupoints compared to non-meridian control regions (NMCR) in humans. Dermal microdialysis in humans showed that NO-cGMP releases in the subcutaneous tissue of acupoint are higher than those in NMCR and increased by electroacupuncture (EA). Recent studies have demonstrated that low-frequency electrical stimulation and manual acupuncture with low stimulating force and rate produce an elevation of NO release predominantly over acupoints. In contrast, NO levels over the areas of the skin regions are moderately reduced by high-frequency EA stimulation. The results from anatomical and biochemical studies consistently show that acupoints exist higher levels of NO signaling molecules, and stimulus-evoked NO release is also with a higher level at acupoints. Results suggest that NO signaling molecules contribute to the specificity of acupoints, and selecting well-trained acupuncturetists for using correct acupoints and appropriate parameters should improve acupuncture clinical trial studies.

Contribution of Adenosine to the Increase in Skeletal Muscle Blood Flow Caused by Manual Acupuncture in Rats

Background and aim

Adenosine is believed to play an important role in local acupuncture analgesia. The aim of this study was to investigate the contribution of adenosine to the increase in skeletal muscle blood flow (MBF) caused by manual acupuncture (MA).

Methods

Thirty-two male Sprague-Dawley rats (310–360 g) were anaesthetised and divided into four equal groups (n=8 each): Saline, Saline+MA, Theophylline, and Theophylline+MA. In the two MA groups, the sparrow-pecking MA technique was applied at 30 repetitions per min for 1 min to a depth of 15–18 mm using a stainless steel acupuncture needle (0.20×40 mm). The stimulus point was located on the right tibialis anterior (TA) muscle 7–8 mm below the knee. Animals in the two theophylline groups were intra-arterially injected with 8-(p-sulphophenyl) theophylline, a non-selective adenosine receptor antagonist, at a dose of 30 mg/kg before MA. Animals in the two saline groups received control saline. Fluorescent microspheres (15 µm in diameter, yellow-green fluorescent) were used for MBF measurement in all four groups.

Results

MA of the TA muscle significantly increased MBF (Saline+MA vs Saline: p=0.001; Saline+MA vs Theophylline: p=0.008). Pre-treatment with theophylline appeared to inhibit this increase (Theophylline vs Theophylline+MA; p=1.000). MBF in the Theophylline+MA group was 43% lower than in the Saline+MA group, although this was not significantly different (p=0.104).

Conclusions

The results suggest that adenosine leads to an increase in MBF caused by MA. Adenosine may play a role in acupuncture analgesia by washing out algesic substances. Further studies are needed in order to elucidate the precise mechanism.

Response of Local Nitric Oxide Release to Manual Acupuncture and Electrical Heat in Humans: Effects of Reinforcement Methods

This study was to examine the influences of manual acupuncture (MA) and electrical heat corresponding to reinforcing methods on nitric oxide (NO) release over the skin regions in humans. A device with collecting solution was taped to the skin surface along pericardium (PC) or lung (LU) meridian. Acupuncture needles were gently inserted into PC 4 with reinforcing stimulation (low force/rate) for 20 minutes in the MA group. LU11 on the finger was heated (43-44°C) by electrical heat for 20 minutes. Biocapture was consecutively conducted for two 20-minute intervals during and after each treatment. Total nitrite and nitrate (NO _x^-) in the collecting samples were quantified using chemiluminescence in blinded fashion. Baseline NO _x^- levels are higher and tended to be higher over PC and LU acupoints during the 1st biocapture. NO _x^- levels over PC regions were consistently increased by MA during both intervals. NO _x^- concentrations over LU acupoints were increased and tended to be increased by electrical heat in the 1st and 2nd biocapture. The results suggest that reinforcing MA and electrical heat induce NO released from the local skin regions with higher levels at acupoints, which improve local circulation and contribute to the beneficial effects of the therapies.

Systemic alterations in plasma proteins from women with chronic widespread pain compared to healthy controls: a proteomic study

Chronic widespread pain (CWP) is a complex pain condition that is difficult to treat. The prevalence of CWP approximates ~10% of the general population, with higher prevalence in women. Lack of understanding of molecular mechanisms has been a challenge for diagnosis and treatment of chronic pain. The aim of this study was to explore the systemic protein changes in CWP compared to those in healthy controls (CON). By applying 2-dimensional gel electrophoresis, we analyzed the protein pattern of plasma samples from women with CWP (n=16) and healthy women (n=23). The proteomic data were analyzed using multivariate statistical models, and altered proteins were identified using mass spectrometry. The proteome analysis was further validated by gel-free Western blot. Multivariate statistical data analysis of quantified proteins revealed 22 altered proteins in women with CWP, compared to CON group. Many of the identified proteins are previously known to be involved in different parts of the complement system and metabolic and inflammatory processes, e.g., complement factor B, vitamin D-binding protein, ceruloplasmin, transthyretin and alpha-2-HS-glycoprotein. These results indicate that important systemic protein differences exist between women with CWP and healthy women. Further, this study illustrates the potential use of proteomics to detect biomarkers that may provide new insights into the molecular mechanism(s) of chronic pain. However, further larger investigations are required in order to confirm these findings before it will be possible to identify proteins as potential pain biomarkers for clinical use.

The local twitch response during trigger point dry needling: Is it necessary for successful outcomes?

BACKGROUND

Myofascial trigger point (MTrP) injection and trigger point dry needling (TrPDN) are widely accepted therapies for myofascial pain syndrome (MPS). Empirical evidence suggests eliciting a local twitch response (LTR) during needling is essential.

OBJECTIVE

This is the first review exploring the available literature, regardless of study design, on the neurophysiological effects and clinical significance of the LTR as it relates to reductions in pain and disability secondary to MTrP needling.

METHODS

PubMed, MEDLINE, Science Direct and Google Scholar were searched up until October 2016 using terms related to trigger point needling and the LTR.

RESULTS

and Discussion: Several studies show that eliciting a LTR does not correlate with changes in pain and disability, and multiple systematic reviews have failed to conclude whether the LTR is relevant to the outcome of TrPDN. Post needling soreness is consistently reported in studies using repeated in and out needling to elicit LTRs and increases in proportion to the number of needle insertions. In contrast, needle winding without LTRs to MTrPs and connective tissue is well supported in the literature, as it is linked to anti-nociception and factors related to tissue repair and remodeling. Additionally, the positive biochemical changes in the MTrP after needling may simply be a wash out effect related to local vasodilation. While the LTR during TrPDN appears unnecessary for managing myofascial pain and unrelated to many of the positive effects of TrPDN, further investigation is required.

Changes of Local Blood Flow in Response to Acupuncture Stimulation: A Systematic Review

Objectives. This systematic review aimed to summarize and evaluate the findings of studies investigating the local microcirculatory effects following acupuncture stimulation. Methods. MEDLINE, EMBASE, OASIS, and Cochrane library were searched to identify randomized controlled trials (RCTs) published before January 30, 2015. Studies demonstrating any type of microcirculation response to manual acupuncture in healthy subjects and patients were included. The risk of bias and the reliability of the experimental conditions were evaluated to determine quality assessment. Results. Eight RCTs met the inclusion criteria; there was at least one acupuncture-induced change in a microcirculatory parameter. Of the seven studies in healthy subjects, four reported significant increases in blood flow following acupuncture compared with control, whereas one other study observed reductions in microcirculation immediately after acupuncture needling. The studies that assessed patients with either fibromyalgia or trapezius myalgia found significant increases in blood flow in the skin and muscle. Additionally, the degree and duration of increases in microcirculation varied depending on the condition of the subjects and the manipulation technique. Conclusions. The current evidence regarding the local effects of acupuncture in terms of blood flow remains insufficient for reliable conclusions due to few well-designed studies. Additional well-designed studies are needed to clarify these issues.

Specific proteins of the trapezius muscle correlate with pain intensity and sensitivity - an explorative multivariate proteomic study of the trapezius muscle in women with chronic widespread pain

Chronic widespread pain (CWP) including fibromyalgia syndrome (FMS) has a high prevalence and is associated with prominent negative consequences. CWP/FMS exhibits morphological and functional alterations in the central nervous system. The importance of peripheral factors for maintaining the central alterations are under debate. In this study, the proteins from biopsies of the trapezius muscle from 18 female CWP/FMS patients and 19 healthy female controls were analyzed. Pain intensity and pressure pain thresholds (PPT) over the trapezius muscles were registered. Twelve proteins representing five different groups of proteins were important regressors of pain intensity in CWP/FMS (R²=0.99; P<0.001). In the regression of PPT in CWP/FMS, it was found that 16 proteins representing six groups of proteins were significant regressors (R²=0.95, P<0.05). Many of the important proteins were stress and inflammation proteins, enzymes involved in metabolic pathways, and proteins associated with muscle damage, myopathies, and muscle recovery. The altered expression of these proteins may reflect both direct and indirect nociceptive/inflammatory processes as well as secondary changes. The relative importance of the identified proteins and central alterations in CWP need to be investigated in future research. Data from this and the previous study concerning the same cohorts give support to the suggestion that peripheral factors are of importance for maintaining pain aspects in CWP/FMS.

Smart photoplethysmographic sensor for pulse wave registration at different vascular depths

The aim of this paper is to propose a smart optical sensor for cardiovascular activity monitoring at different tissue layers. Photoplethysmography (PPG) is a noninvasive optical technique for monitoring mainly blood volume changes in the examined tissue. However, different important physiological parameters, such as oxygen saturation, heart and breathing rate, dynamics of skin micro-circulation, vasomotion activity etc., can be extracted from the registered PPG signal. The developed sensor consists of 32 light emitting sources with four different wavelengths, which are located to the four different distances from four photo detectors. Compared to the existing sensors, the system enables to select the optimal LED (light emitting diode) and photo detector couple in order to obtain the pulse wave signal from the interested blood vessels with the highest possible signal to noise ratio. In this study, the designed PPG sensor was tested for the pulse wave registration from radial artery. The highest efficiency and signal to noise ratio was achieved using infrared LED (940 nm) and photo-diode pair.

Transcutaneous Electrical Stimulation Increased Nitric Oxide-Cyclic GMP Release Biocaptured Over Skin Surface of Pericardium Meridian and Acupuncture Points in Humans

OBJECTIVES

The purpose of this study was to consecutively capture and quantify nitric oxide (NO) and cGMP, the second messenger of NO, over the skin surface of acupuncture points (acupoints), meridian line without acupoint, and non-meridian control regions of the Pericardium meridian (PC) in humans, and investigate their response to transcutaneous electrical nerve stimulation (TENS) . DESIGN, SETTING, AND MAIN OUTCOME MEASURES: Adhesive biocapture tubes were attached to the skin surface along PC regions and injected with 2-Phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl solution, an NO-scavenging compound, contacting the skin surface for 20 minutes each during 4 consecutive biocapture intervals. TENS (1.0 mA, 6 Hz, 1.0 msec duration) was applied over acupoints PC 8 and PC 3 during the 2nd biocapture for 20 min. Total nitrite and nitrate (NO(x)-), the stable metabolic products of NO, and cGMP in biocaptured samples were quantified using chemiluminescence and ELISA.

RESULTS

NO(x)- levels in the 1st biocapture over PC regions are almost two fold higher compared to subsequent biocaptures and are higher over PC acupoints versus non-meridian control region. Following TENS, NO(x)- concentrations over PC regions were significantly increased, and cGMP is predominantly released from the skin surface of PC acupoints.

CONCLUSIONS

TENS induces elevations of NO-cGMP concentrations over local skin region with a high level at acupoints. The enhanced signal molecules improve local circulation, which contributes to beneficial effects of the therapy.

Protein alterations in women with chronic widespread pain--An explorative proteomic study of the trapezius muscle

Chronic widespread pain (CWP) has a high prevalence in the population and is associated with prominent negative individual and societal consequences. There is no clear consensus concerning the etiology behind CWP although alterations in the central processing of nociception maintained by peripheral nociceptive input has been suggested. Here, we use proteomics to study protein changes in trapezius muscle from 18 female patients diagnosed with CWP compared to 19 healthy female subjects. The 2-dimensional gel electrophoresis (2-DE) in combination with multivariate statistical analyses revealed 17 proteins to be differently expressed between the two groups. Proteins were identified by mass spectrometry. Many of the proteins are important enzymes in metabolic pathways like the glycolysis and gluconeogenesis. Other proteins are associated with muscle damage, muscle recovery, stress and inflammation. The altered expressed levels of these proteins suggest abnormalities and metabolic changes in the myalgic trapezius muscle in CWP. Taken together, this study gives further support that peripheral factors may be of importance in maintaining CWP.

Reliability of muscle blood flow measurements in orbicularis oculi

PURPOSE

Orbicularis oculi muscle tension and muscle blood flow have been shown to be objective measures of eyestrain during visually demanding activities, such as computer work. In line with this, positive associations between eye-related pain and muscle blood flow in orbicularis oculi have been observed. A hypothesis regarding work situations with cognitive tasks and low-level muscle activity, such as computer work, proposes that muscle pain originates from the blood vessel-nociceptor interactions of the connective tissue of the muscle. Noninvasive muscle blood flow measurements in the orbicularis oculi muscle are preferable to using an invasive technique. The aim of this study was to test reproducibility and stability of muscle blood recordings in orbicularis oculi using photoplethysmography.

METHODS

In the reproducibility tests, 12 subjects were tested twice within 1 to 5 weeks. To study the stability of the method, six of the subjects were randomly selected and tested four more times within 2 to 6 weeks. Test subjects were doing identical visually demanding computer work for 10 minutes in each test.

RESULTS

The short-term repeatability of muscle blood flow measurements was considered good, but the stability of blood flow recordings over time in orbicularis oculi was low because of a greater within-subject maximum variability compared with between-subject average variability.

CONCLUSIONS

Investigators should be aware of the effect of time, possibly attributed to confounding factors such as environmental changes and mental stress, when comparing photoplethysmography muscle blood flow recordings.

Distal traditional acupuncture points of the large intestinal meridian and the stomach meridian differently affect heart rate variability and oxygenation of the trapezius muscle

Physicians in traditional Chinese medicine have found that acupoints and meridians have effects on specific parts of the body. The aim of this study was to see how acupressure at distal acupuncture points of a specific meridian affects heart rate variability (HRV) and oxygenation of the trapezius muscle. Forty-one female participants were randomly allocated to three groups. Subjects in the Stomach Meridian acupuncture point (ST) group received acupressure at ST 34, ST 36, and ST 41, subjects in the Large Intestinal Meridian acupuncture point (LI) group received acupressure at LI 4, LI 10, and LI 11, and subjects in the control group did not receive any stimuli. HRV and oxygenation of the trapezius muscles were measured. The high frequency components of HRV in the control and LI groups tended to be higher than those in the ST group. Total hemoglobin in the control and LI groups eventually reached significantly higher levels than in the ST group. While oxyhemoglobin (ΔO2Hb) in the control and LI groups did not change, ΔO2Hb in the ST significantly decreased temporarily.

Physiologic effects of dry needling

During the past decades, worldwide clinical and scientific interest in dry needling (DN) therapy has grown exponentially. Various clinical effects have been credited to dry needling, but rigorous evidence about its potential physiological mechanisms of actions and effects is still lacking. Research identifying these exact mechanisms of dry needling action is sparse and studies performed in an acupuncture setting do not necessarily apply to DN. The studies of potential effects of DN are reviewed in reference to the different aspects involved in the pathophysiology of myofascial triggerpoints: the taut band, local ischemia and hypoxia, peripheral and central sensitization. This article aims to provide the physiotherapist with a greater understanding of the contemporary data available: what effects could be attributed to dry needling and what are their potential underlying mechanisms of action, and also indicate some directions at which future research could be aimed to fill current voids.

Are physiological changes experienced by healthy subjects during acu-TENS associated with acupuncture point sensations?

BACKGROUND

Transcutaneous electrical nerve stimulation over acupuncture points (acu-TENS) has been reported to improve clinical outcomes. The objectives of the present study were to investigate whether acupuncture point sensations were experienced during acu-TENS, and whether such sensations were associated with any concomitant changes in autonomic nervous system activity.

METHODS

This study adopted a single-blinded, randomised, controlled trial methodology. A total of 36 healthy subjects were randomly assigned to an experimental group (acu-TENS on right LI4 and LI11 points); control group (acu-TENS to bilateral kneecaps); or placebo group (sham acu-TENS on right LI4 and LI11 points). Heart rate (HR), mean arterial blood pressure (MAP), SD of the NN interval (SDNN) and low frequency to high frequency ratio (LF/HF) were measured before, during and after intervention. The Hong Kong Chinese version of the Massachusetts General Hospital Acupuncture Sensation Scale (C-MMASS) index was used for quantifying the acupuncture point stimulation sensations.

RESULTS

The experimental group showed a significant increase in HR (mean (SD) 73.5 (6.3) to 75.9 (6.7) bpm, p=0.027), MAP (88.5 (4.5) to 91.0 (4.1) mm Hg, p=0.004), SDNN (143.36 (8.58) to 153.69 (7.64) ms, p=0.002) and LF/HF (1.26 (0.19) to 1.31 (0.21), p=0.037) during the intervention. The control group showed a significant increase in SDNN (140.21 (8.72) to 143.39 (9.47) ms, p=0.009) and LF/HF (1.21 (0.09) to 1.23 (0.12), p=0.033). There were no significant physiological changes in the placebo group. Overall C-MMASS indices for the experimental, control and placebo groups were 3.23 (0.3), 2.14 (0.6) and 0.29 (0.32), respectively. The between-group difference was statistically significant (F=139.24, df=2, p<0.05). However, correlation analysis did not support any association between sensation intensity and physiological responses in any groups (γ ranged from -0.36 to 0.25).

CONCLUSIONS

This study showed that 'acupuncture point sensations' were experienced during acu-TENS to LI4 and LI11, but such sensations were not associated with physiological responses induced during the stimulation.

Investigating the effects of three needling parameters (manipulation, retention time, and insertion site) on needling sensation and pain profiles: a study of eight deep needling interventions

Introduction. In traditional Chinese acupuncture, needle sensation (deqi) is purported to contribute to a therapeutic outcome. While researchers have attempted to define deqi qualitatively, few have examined the effects of needling parameters on its intensity. Methods. 24 healthy subjects completed eight interventions scheduled at least one week apart, which involved manual acupuncture to LI4 or a designated nonacupoint (NAP) on the hand, with real or simulated manipulation each three minutes and needle retentions of one or 21 minutes. Intensities of needling sensation and pain were reported every three minutes and sensation qualities were reported post-intervention. Results. Immediately after needle insertion, similar levels of mean needle sensation and of pain were reported independent of intervention. At subsequent measurement times, only two interventions (one at LI4 and one at NAP) maintained statistically significantly elevated needle sensation and pain scores and reported higher numbers of needle sensation descriptors. For both, the needle was retained for 21 minutes and manipulated every three minutes. Neither intervention differed significantly in terms of levels of pain, and needle sensation or numbers and qualities of needle sensation described. Conclusion. In this group of healthy subjects, the initial needling for all eight interventions elicited similar levels of needle sensation and pain. These levels were only maintained if there was ongoing of needle manipulation and retention of the needle. By contrast, the strength of needle sensation or pain experienced was independent of insertion site.

The influence of dry needling of the trapezius muscle on muscle blood flow and oxygenation

OBJECTIVE

The purpose of this study was to investigate the effect of dry needling on the blood flow and oxygen saturation of the trapezius muscle.

METHODS

Twenty healthy participants participated in this study. One single dry needling procedure was performed in the right upper trapezius, at a point located midway between the acromion edge and the seventh cervical vertebrae. Using the oxygen to see device, blood flow and oxygen saturation were evaluated at the treated point and 3 distant points (similar point in the left upper trapezius and 30 mm laterally from this midpoint). Measurements were taken at baseline and in the recovery period (0, 5, and 15 minutes posttreatment).

RESULTS

After removal of the needle, the blood flow and oxygen saturation increased significantly from the pretreatment level in the treated point (P ≤ .001), and these values remained high throughout the 15-minute recovery period. There were only minor changes in the distant points.

CONCLUSIONS

These results suggest that dry needling enhances the blood flow in the stimulated region of the trapezius muscle but not in a distant region used in this study.

Urinary albumin, protein excretion and circadian blood pressure in patients with fibromyalgia

Recent evidence suggests that patients with fibromyalgia (FM) have increased oxidative stress, inflammation, endothelial dysfunction and autonomic dysfunction. These factors are also shown to be responsible for increased urinary albumin and protein excretion and deranged circadian blood pressure (BP). However, no study has examined the 24-h urinary albumin excretion (UAE), 24-h urinary protein excretion (UPE) and 24-h ambulatory BP measurements in FM patients. The sociodemographic, laboratory parameters, depressive symptoms, sleep problems and 24-h ambulatory BPs were measured for all patients. Diagnosis of FM was based on the criteria for the classification of FM by the American College of Rheumatology. After diagnosis of FM, these patients underwent to complete the Fibromyalgia Impact Questionnaire (FIQ). In total, 30 patients with FM and 61 patients without FM were included. Among FM patients, the average number of tender points was 13.1 ± 1.57 and the mean FIQ score was 57.9 ± 8.86. The number of tender points did not show any correlation with office and ambulatory BPs. There were also no correlations between the number of tender points, UPE and UAE. The stepwise linear regression did not show any relation between UPE and FM. However, 24-h UAE was independently correlated with office systolic BP (P 0.008) and the presence of FM (P 0.045). The logistic regression analysis revealed no association between FM and non-dipping status. We suggest that circadian blood pressure and UPE are not independently associated with FM. However, UAE was related with the presence of FM. Studies are needed to confirm our findings and to highlight pathophysiologic mechanisms.

Participation of Calcitonin Gene Related Peptide Released via Axon Reflex in the Local Increase in Muscle Blood Flow following Manual Acupuncture

Objective

The purpose of this study was to determine how calcitonin gene related peptide (CGRP) via axon reflex participates in increasing local muscle blood flow (MBF) following manual acupuncture (MA).

Methods

Male Sprague–Dawley rats (N=56, 270–350 g) were used. We examined (1) the effects of MA on MBF in the tibialis anterior (TA) muscle in normal rats; (2) the effects of MA on MBF in the TA injected with saline or hCGRP8-37 (low: 2×10−4 mol/litre; high: 2×10−3 mol/litre), a competitive CGRP receptor antagonist, in rats; and (3) the effects of MA on MBF in the TA in capsaicin-treated rats. The capsaicin-treated rats were injected with capsaicin dissolved in an ethanol solution within 24 h after birth (50 mg/kg subcutaneously). MA was applied to the right TA for 1 min. 51Cr-labelled microspheres (15 μm in diameter) were used to measure MBF.

Results

MA significantly increased MBF without changing arterial blood pressure in normal rats (p<0.05). MA also significantly increased MBF in saline-injected, low hCGRP8-37-injected and high hCGRP8-37-injected rats (p<0.001, 005 and 0.05, respectively). The increases in low and high hCGRP8-37-injected rats were lower than those in saline-injected rats, but the difference was not significant. However, MA did not significantly increase MBF in capsaicin-treated rats (p=0.38).

Conclusions

We obtained conflicting results, suggesting that the participation of CGRP released via axon reflex may be limited to a local increase in MBF following MA.

Decreased muscle concentrations of ATP and PCR in the quadriceps muscle of fibromyalgia patients--a 31P-MRS study

BACKGROUND AND METHODS

Fibromyalgia (FMS) has a prevalence of approximately 2% in the population. Central alterations have been described in FMS, but there is not consensus with respect to the role of peripheral factors for the maintenance of FMS. 31P magnetic resonance spectroscopy (31P-MRS) has been used to investigate the metabolism of phosphagens in muscles of FMS patients, but the results in the literature are not in consensus. The aim was to investigate the quantitative content of phosphagens and pH in resting quadriceps muscle of patients with FMS (n = 19) and in healthy controls (CONTROLS; n = 14) using (31) P-MRS. It was also investigated whether the concentrations of these substances correlated with measures of pain and/or physical capacity.

RESULTS

Significantly lower concentrations of adenosine triphosphate (ATP) and phosphocreatinine (PCr; 28-29% lower) were found in FMS. No significant group differences existed with respect to inorganic phosphate (Pi), Pi/PCr and pH. The quadriceps muscle fat content was significantly higher in FMS than in CONTROLS [FMS: 9.0 ± 0.5% vs.

CONTROLS

6.6 ± 0.6%; (mean ± standard error); P = 0.005]. FMS had significantly lower hand and leg capacity according to specific physical test, but there were no group differences in body mass index, subjective activity level and in aerobic fitness. In FMS, the specific physical capacity in the leg and the hand correlated positively with the concentrations of ATP and PCr; no significant correlations were found with pain intensities.

CONCLUSIONS

Alterations in intramuscular ATP, PCr and fat content in FMS probably reflect a combination of inactivity related to pain and dysfunction of muscle mitochondria.

Effects of nitric oxide synthase inhibition on cutaneous vasodilation in response to acupuncture stimulation in humans

OBJECTIVES

The aim of the present study was to elucidate the mechanism of cutaneous vasodilation following acupuncture stimulation by investigating the roles of nitric oxide (NO) and axon reflex vasodilation.

METHODS

The subjects were 17 healthy male volunteers. The role of NO was investigated by administering N(G)-nitro-l-arginine methyl ester hydrochloride (L-NAME, 20 mM), an NO synthase inhibitor or Ringer's solution (control site), via intradermal microdialysis (protocol 1; n=7). The role of axon reflex vasodilation by local sensory neurones was investigated by comparing vasodilation at sites treated with 'eutectic mixture of local anaesthetics' (EMLA) cream (2.5% lidocaine and 2.5% prilocaine) with untreated sites (control site) (protocol 2; n=10). After 5 min of baseline recording, acupuncture was applied to PC4 and a control site in proximity to PC4 for 10 min and scanning was performed for 60 min after acupuncture stimulation. Skin blood flow (SkBF) was evaluated by laser Doppler perfusion imaging. Cutaneous vascular conductance (CVC) was calculated from the ratio of SkBF to mean arterial blood pressure.

RESULTS

In the first protocol, sites administered L-NAME showed significant reductions in CVC responses following acupuncture stimulation compared to control sites (administered Ringer's solution) (p<0.05). In the second protocol, changes in CVC responses after acupuncture stimulation did not differ significantly between treated sites with EMLA cream and untreated sites (p>0.05).

CONCLUSIONS

These data suggest that cutaneous vasodilation in response to acupuncture stimulation may not occur through an axon reflex as previously reported. Rather, NO mechanisms appear to contribute to the vasodilator response.

Autonomic regulation, physical activity and perceived stress in subjects with musculoskeletal pain: 24-hour ambulatory monitoring

The aim of the study was to investigate autonomic nervous system regulation, physical activity (PA) and perceived stress and energy during daily activities in subjects with chronic muscle pain in the neck-shoulders (trapezius myalgia) (n=23) and symptom-free controls (n=22). Subjects underwent 24-hour objective ambulatory monitoring of heart rate variability (HRV) and PA, and reported their perceived stress and energy in a diary. Standard HRV measures were extracted in time and frequency domains. The volume and pattern of different types of activities were quantified in terms of intensity and duration of walking, and time spent sitting, standing and lying during the 24-hour measurement. Results showed shortened inter-beat-intervals (higher heart rate) and reduced HRV in the pain group, most pronounced during sleep (p<0.05). For overall PA, the pain group showed increased lying time, compared to controls (p<0.05). A different activity pattern was found in the pain group, with reduced leisure time PA and increased PA during morning hours, in comparison with controls (p<0.05). Both groups demonstrated low levels of perceived stress, whereas reduced energy was observed in the pain group (p<0.05). In conclusion, monitoring of 24-hour HRV demonstrated diminished HRV among persons with chronic neck-shoulder pain. This reflected aberration in autonomic regulation, suggesting reduced parasympathetic activation and increased sympathetic tone as an element in maintenance of chronic muscle pain.

Neural and psychosocial mechanisms of pain sensitivity in fibromyalgia

Fibromyalgia is a chronic musculoskeletal pain disorder that affects an estimated 5 million adults in the U.S. The hallmark is burning, searing, tingling, shooting, stabbing, deep aching, or sharp pain. Fibromyalgia is generally considered to be a "central sensitivity syndrome" where central sensitization is regarded as the cause of pain in its own right. Nonetheless, the case continues to be made that all central and spatially distributed peripheral components of fibromyalgia pain would fade if the peripheral generators could be silenced. Although neural mechanisms are clearly important in pain sensitivity, cognitive and social mechanisms also need to be considered. The aim of this review is to examine four mechanisms responsible for heightened pain sensitivity in fibromyalgia: peripheral sensitization, central sensitization, cognitive-emotional sensitization, and interpersonal sensitization. The purpose of framing the review in terms of pain sensitivity in fibromyalgia is to highlight that different mechanisms of sensitization are appropriately regarded as intervening variables when it comes to understanding individual differences in the experience of pain. The paper concludes by considering the implications of the findings of the review for explanations of fibromyalgia pain by nurses working in multidisciplinary teams. The trend appears to be able to explain the cause of fibromyalgia pain in terms of sensitization per se. The recommended alternative is to explain fibromyalgia pain in terms of changes in pain sensitivity and the role of underlying neural and psychosocial mechanisms.

Effect of muscle load tasks with maximal isometric contractions on oxygenation of the trapezius muscle and sympathetic nervous activity in females with chronic neck and shoulder pain

Background

Sympathetic nervous activity contributes to the maintenance of muscle oxygenation. However, patients with chronic pain may suffer from autonomic dysfunction. Furthermore, insufficient muscle oxygenation is observed among workers with chronic neck and shoulder pain. The aim of our study was to investigate how muscle load tasks affect sympathetic nervous activity and changes in oxygenation of the trapezius muscles in subjects with chronic neck and shoulder pain.

Methods

Thirty females were assigned to two groups: a pain group consisting of subjects with chronic neck and shoulder pain and a control group consisting of asymptomatic subjects. The participants performed three sets of isometric exercise in an upright position; they contracted their trapezius muscles with maximum effort and let the muscles relax (Relax). Autonomic nervous activity and oxygenation of the trapezius muscles were measured by heart rate variability (HRV) and Near-Infrared Spectroscopy.

Results

Oxyhemoglobin and total hemoglobin of the trapezius muscles in the pain group were lower during the Relax period compared with the control group. In addition, the low frequency / high frequency (LF/HF) ratio of HRV significantly increased during isometric exercise in the control group, whereas there were no significant changes in the pain group.

Conclusions

Subjects with neck and shoulder pain showed lower oxygenation and blood flow of the trapezius muscles responding to isometric exercise, compared with asymptomatic subjects. Subjects with neck and shoulder pain also showed no significant changes in the LF/HF ratio of HRV responding to isometric exercise, which would imply a reduction in sympathetic nervous activity.

Influence of scapular position on the pressure pain threshold of the upper trapezius muscle region

A position of scapula depression will maintain the upper trapezius muscle region in a lengthened position, causing excessive strain. This strain could lead to peripheral nociceptive nerves sensitization in the affected area, changing the pressure pain threshold (PPT). Thus, people with a faulty alignment of scapular depression may have lower PPT levels in the upper trapezius region when compared to subjects with normal vertical scapular position. The purpose of this double-blind study was to assess the influence of scapular position on the PPT of the upper trapezius region in a young healthy population. Fifty two physical therapy students of the Catholic University of Minas Gerais-PUC-Minas, Brazil, with normal shoulder (NS group, n=26, 6 men and 20 women) or depressed shoulder (DS group, n=26, 6 men and 20 women) volunteered to participate in this study. An electronic pressure algometer was used to measure the PPT on the upper trapezius muscle region. The results showed a significant difference between groups, with the DS group (19.0+/-9.0 N/cm(2)) demonstrated lower mean PPT values when compared to NS group (26.1+/-9.6 N/cm(2)) (p<0.01). Our results showed that healthy young subjects with depressed scapula position had significant lower upper trapezius PPT values when compared to subjects with normal scapula position.