Clinical effectiveness of trigger point acupuncture on chronic neck and shoulder pain (katakori) with work productivity loss in office workers: a randomized clinical trial.

OBJECTIVES: To evaluate whether trigger point acupuncture (TrPA) is beneficial for office workers who have reduced job performance (presenteeism) due to chronic neck and shoulder pain (katakori). METHODS: A 4-week single-center randomized controlled trial was conducted on 20 eligible female office workers with chronic neck and shoulder pain of at least 3-month duration. The control group implemented only workplace-recommended presenteeism measures, whereas the intervention group received TrPA up to 4 times per month in addition to the presenteeism measures recommended by each workplace. The major outcome measure was the relative presenteeism score on the World Health Organization Health and Work Performance (WHO-HPQ). The secondary outcome measures were pain intensity (numerical rating scale), absolute presenteeism (WHO-HPQ), anxiety and depression (Hospital Anxiety and Depression Scale; HADS), catastrophic thoughts related to pain (Pain Catastrophizing Scale; PCS), and sleep (Athens Insomnia Scale; AIS). RESULTS: All 9 cases in the intervention group and 11 cases in the control group were analyzed. TrPA up to 4 times per month reduced the intensity of neck and shoulder pain by 20% (P < .01, d = 1.65) and improved labor productivity (relative presenteeism value) by 0.25 (P < .01, d = 1.33) compared with the control group over 1 month. No significant differences were observed between the 2 groups in terms of absolute presenteeism score, HADS, PCS, or AIS. CONCLUSIONS: These results suggest that regular intervention with TrPA may be effective in the relative presenteeism score before and after the intervention and the degree of neck and shoulder pain over 28 days compared with the control group.

Effect of Catastrophic Thinking on the Analgesic Effect of Electroacupuncture.

Introduction: Patients with chronic pain and high-level catastrophic thoughts often do not respond to acupuncture. This may be related to hypofunctioning of the dorsolateral prefrontal cortex and the descending pain inhibitory system. Therefore, we examined the relationship between the level of catastrophic thinking and the analgesic effect of electroacupuncture using the pain catastrophizing scale (PCS). We also evaluated the descending pain inhibitory system using conditioned pain modulation (CPM) and offset analgesia (OA). The relationship between catastrophic thinking and the descending pain inhibitory system was also examined. Materials and Methods: After testing the hospital anxiety and depression scale and the PCS in 14 healthy adults, the current pain threshold (CPT), CPM, and OA were measured, in order, before the intervention. Thereafter, electroacupuncture was applied to 3 limbs (the dominant hand and both lower extremities) at 4 Hz, and to the scalp at 100 Hz, for 30 minutes, and the CPT was measured again immediately after the intervention. The difference in the CPT before and after the intervention was taken as the analgesic effect. Results: The participants were divided into 2 groups, the H-PCS group (≥16 points) and the L-PCS group (≤15 points), according to the PCS score, and the analgesic effects of electroacupuncture were significantly different (P = 0.04). However, no relationship was found between the PCS score and the CPM (r = -0.02, P = 0.94) and OA effects (r = -0.19, P = 0.49). Conclusion: It was suggested that people with high-level catastrophic thinking may find it difficult to obtain the analgesic effects of electroacupuncture.

Effects of Acupuncture Therapy on Drug-Resistant Fibromyalgia: An Exploratory Single-Arm Nonrandomized Trial.

Introduction: Fibromyalgia is a chronic illness that causes symptoms such as pain. In Japan, although pregabalin and duloxetine are the drugs of choice for fibromyalgia, they may be ineffective or may cause side-effects. Studies have reported on the efficacy of acupuncture against fibromyalgia. However, acupuncture is not always effective in clinical practice, and the reason for this is thought to be the dysfunction of the descending pain control system. This study aimed to determine whether the combined use of electro-scalp acupuncture and conventional electroacupuncture reduces fibromyalgia symptoms and drug dosage requirements. Methods: Patients with intractable fibromyalgia (visual analog scale [VAS] score ≥50 mm; Japanese version of the Fibromyalgia Impact Questionnaire [JFIQ] score ≥50) receiving pregabalin were recruited in this single-arm nonrandomized uncontrolled study. They underwent electroacupuncture on four limbs plus electro-scalp acupuncture once a week for 5 weeks. Drug intake, pain (as determined using VAS), quality of life (QOL; as determined using JFIQ), anxiety, depression, catastrophic thoughts, and sleep were assessed. Results: Although there was no increase in drug intake, 42.8% (3/7) of patients reduced pregabalin intake by approximately 10% (a moderate though insignificant effect). Pain levels significantly declined (VAS 75.4 ± 11.7 mm to 64.3 ± 17.3 mm; P = 0.05) and QOL significantly improved (JFIQ 67.0 ± 13.4 to 50.9 ± 18.3; P = 0.02). The parameters for anxiety, depression, catastrophic thoughts, and sleep did not significantly change. Conclusion: The combination of conventional electroacupuncture plus electro-scalp acupuncture may effectively alleviate pain, improve QOL, and reduce pregabalin dosage requirements in patients with fibromyalgia.

Trigger Point Acupuncture and Exercise for Chronic Low Back Pain in Older Adult: a Preliminary Randomized Clinical Trial.

Background: Exercise therapy is the first choice non-pharmacotherapeutic approach for musculoskeletal pain; however, it often interferes with the implementation and continuation of exercise due to fear-avoidance behaviors. Trigger point acupuncture (TrPAcp) has been reported to reduce musculoskeletal pain. Objectives: To examine the efficacy of exercise combined with TrPAcp compared to exercise alone for older patients with chronic low back pain (CLBP), the most common subjective symptom reported by old people of both sexes in Japan. Methods: In this single-center randomized controlled trial conducted at Teikyo Heisei University, 15 men and women aged ≥ 65 years with low back pain for at least 3 months who met the eligibility criteria were included. The Ex+TrPAcp group received exercise and trigger point acupuncture, while the Ex group received only exercise for 3 months. The main outcome, pain intensity, was measured using the numerical rating scale (NRS). Improvement was defined as a decrease in NRS of ≥ 2 or less than moderate (NRS < 4). Results: The analysis included 7 of 8 cases in the Ex+TrPAcp group and 7 of 7 cases in the Ex group. NRS improved in 6 of 7 and 1 of 7 patients in the intervention and control groups, respectively, with a significant difference between groups (p = 0.03, ϕ = 0.71). Regarding adverse events due to acupuncture, one patient (14.3%) complained of heaviness after acupuncture. Nothing specific was reported with exercise. Conclusion: Compared with Ex alone, Ex+TrPAcp may be more effective therapy for older people with CLBP who do not have an exercise habit.

Effect of acupuncture on the haemodynamic system in men.

BACKGROUND: Acupuncture stimulation decreases heart rate (HR) through somato-autonomic reflexes. However, the mechanisms responsible for other cardiovascular changes induced by acupuncture, such as its effects on stroke volume (SV) and blood pressure (BP), remain obscure. OBJECTIVE: To evaluate continuously the comprehensive cardiovascular changes occurring during acupuncture. METHOD: 20 healthy men participated in the study. HR, SV and BP were measured in the supine position using electrocardiogram, transthoracic impedance cardiography and continuous non-invasive finger blood pressure, respectively. Manual acupuncture stimulation using a stainless steel needle was performed at LI10 for 60 s after resting periods of approximately 15 min. RESULTS: HR was reduced and SV increased, in parallel, during the period of acupuncture stimulation (P<0.01, respectively). Diastolic blood pressure (DBP) decreased in the 10 s period of acupuncture stimulation compared with the 120 s pre-stimulation period (P<0.01) and recovered close to the pre-stimulation reading instantly after the transient reduction. No change was observed in cardiac output (CO) derived from HR and SV. CONCLUSIONS: This study indicates that HR reduction during acupuncture does occur, as previous reports have indicated. SV increased during acupuncture stimulation in parallel with HR reduction and CO was maintained during these changes. Any reduction in DBP caused by acupuncture recovered to baseline, likely due to baroreflexes.

Mechanism of Electroacupuncture on Postoperative Ileus Induced by Surgical Stress in Rats.

Objectives: Acupuncture has been used for treating gastrointestinal (GI) disorders such as postoperative nausea and vomiting. Electroacupuncture (EA) accelerates GI transit following surgery and ameliorates postoperative ileus (POI) to restore colonic transit (CT); however, the mechanisms of this EA-induced restoration remain unclear. The aims of this study were to show CT following surgery and the effects of EA at ST 36 on POI induced by surgical stress (SS) in 45 conscious, male Sprague-Dawley rats. Materials and Methods: An operation was performed in each rat, setting a cannula into the cecum to connect the proximal colon to inject markers. On the day after surgery, 20 metal radiopaque markers were administered to the proximal colon of each rat. These markers were visible throughout the GI tract on soft X-ray immediately after administration and up to 240 minutes afterward. The rats were divided into 5 groups with 9 rats in each group: (1) SS; (2) 5 days post surgery (POST-5D); (3) SS + phentolamine; (4) EA alone; and (5) EA + atropine. The EA was performed at ST 36 for 20 minutes at a frequency of 10 Hz and agents were administered in the appropriate groups before markers were administered and measurements were taken. Measurements were performed the day after surgery except in the POST 5-D group. CT was calculated by the geometric center on the images showing the CT for each rat. Results: CT after surgery was delayed significantly and phentolamine accelerated CT. EA restored CT following surgery and atropine abolished the effect of EA on CT. Conclusions: The current study demonstrated that surgery induced a delay in CT through the sympathetic pathway via α-adrenoreceptors; CT was restored by EA. These results suggest that EA can be used to treat POI through mediation of the autonomic nervous system.

Randomized trial of trigger point acupuncture treatment for chronic shoulder pain: a preliminary study.

There is evidence for the efficacy of acupuncture treatment for chronic shoulder pain, but it remains unclear which acupuncture modes are most effective. We compared the effect of trigger point acupuncture (TrP), with that of sham (SH) acupuncture treatments, on pain and shoulder function in patients with chronic shoulder pain. The participants were 18 patients (15 women, 3 men; aged 42-65 years) with nonradiating shoulder pain for at least 6 months and normal neurological findings. The participants were randomized into two groups, each receiving five treatment sessions. The TrP group received treatment at trigger points for the muscle, while the other group received SH acupuncture treatment on the same muscle. Outcome measures were pain intensity (visual analogue scale, VAS) and shoulder function (Constant-Murley Score: CMS). After treatment, pain intensity between pretreatment and 5 weeks after TrP decreased significantly (p<0.001). Shoulder function also increased significantly between pretreatment and 5 weeks after TrP (p<0.001). A comparison using the area under the outcome curves demonstrated a significant difference between groups (p=0.024). Compared with SH acupuncture therapy, TrP therapy appears more effective for chronic shoulder pain.

[Mechanisms of acupuncture and moxibustion on symptoms of neurology].

There is some evidence for the efficacy of acupuncture and moxibustion treatment in symptoms of neurology (pain, anxietas, depression and motor ability), but the mechanisms of acupuncture and moxibustion remain unclear. We examined the remediation mechanisms of acupuncture and moxibustion on symptoms (pain, anxietas, depression and motor ability). Some of papers reported that the serotonin and dopamine was increased in brain by the acupuncture and moxibustion. In addition, the treatments of acupuncture and drug reported less depression intensity than the drug only. These results suggest that the serotonin and dopamine in brain was improved by the acupuncture and moxibustion, and acupuncture and drug therapy may be more effective on symptoms (pain, anxietas, depression, motor ability) than drug therapy.

Effects of trigger point acupuncture treatment on temporomandibular disorders: a preliminary randomized clinical trial.

We compared the effects of trigger point acupuncture with that of sham acupuncture treatments on pain and oral function in patients with temporomandibular disorders (TMDs). This 10-week study included 16 volunteers from an acupuncture school with complaints of chronic temporomandibular joint myofascial pain for at least 6 months. The participants were randomized to one of two groups, each receiving five acupuncture treatment sessions. The trigger point acupuncture group received treatment at trigger points for the same muscle, while the other acupuncture group received sham treatment on the trigger points. Outcome measures were pain intensity (visual analogue scale) and oral function (maximal mouth opening). After treatment, pain intensity was less in the trigger point acupuncture group than in the sham treatment group, but oral function remained unchanged in both groups. Pain intensity decreased significantly between pretreatment and 5 weeks after trigger point (p<0.001) and sham acupunctures (p<0.050). Group comparison using the area under the curve demonstrated a significant difference between groups (p=0.0152). Compared with sham acupuncture therapy, trigger point acupuncture therapy may be more effective for chronic temporomandibular joint myofascial pain.

Effect of acupuncture depth on muscle pain.

BACKGROUND: While evidence supports efficacy of acupuncture and/or dry needling in treating musculoskeletal pain, it is unclear which needling method is most effective. This study aims to determine the effects of depth of needle penetration on muscle pain. METHODS: A total of 22 healthy volunteers performed repeated eccentric contractions to induce muscle soreness in their extensor digital muscle. Subjects were assigned randomly to four groups, namely control group, skin group (depth of 3 mm: the extensor digital muscle), muscle group (depth of 10 mm: the extensor digital muscle) and non-segmental group (depth of 10 mm: the anterior tibial muscle). Pressure pain threshold and electrical pain threshold of the skin, fascia and muscle were measured at a point 20 mm distal to the maximum tender point on the second day after the exercise. RESULTS: Pressure pain thresholds of skin group (depth of 3 mm: the extensor digital muscle) and muscle group (depth of 10 mm: the extensor digital muscle) were significantly higher than the control group, whereas the electrical pain threshold at fascia of muscle group (depth of 10 mm: the extensor digital muscle) was a significantly higher than control group; however, there was no significant difference between the control and other groups. CONCLUSION: The present study shows that acupuncture stimulation of muscle increases the PPT and EPT of fascia. The depth of needle penetration is important for the relief of muscle pain.

Effects of acupuncture to treat fibromyalgia: a preliminary randomised controlled trial.

BACKGROUND: Acupuncture is often used to treat fibromyalgia (FM), but it remains unclear whether acupuncture is effective. This study aims to evaluate the effects of acupuncture on pain and quality of life (QoL) in FM patients. METHODS: Sixteen patients (13 women and 3 men aged 25-63 years) suffering from FM were randomised into two groups: group A (n = 8) received five acupuncture treatments after the fifth week and group B received ten acupuncture treatments. Outcome measures used in this study were pain intensity (visual analogue scale, VAS) and the fibromyalgia impact questionnaire (FIQ). RESULTS: After the fifth week, pain intensity (U = 25.0; P = 0.022) in group B decreased and QoL (U = 24.5; P = 0.026) improved compared to group A. CONCLUSION: The present study suggests that acupuncture treatment is effective to relieve pain for FM patients in terms of QoL and FIQ.

A pilot study on using acupuncture and transcutaneous electrical nerve stimulation to treat chronic non-specific low back pain.

OBJECTIVE: The present study tests whether a combined treatment of acupuncture and transcutaneous electrical nerve stimulation (TENS) is more effective than acupuncture or TENS alone for treating chronic low back pain (LBP). METHODS: Thirty-two patients with chronic LBP were randomly allocated to four groups. The acupuncture group (ACP) received only acupuncture treatment at selected acupoints for low back pain; the TENS group (TENS) received only TENS treatment at pain areas; the acupuncture and TENS group (A&T) received both acupuncture and TENS treatments; the control group (CT) received topical poultice (only when necessary). Each group received specific weekly treatment five times during the study. Outcome measures were pain intensity in terms of visual analogue scale (VAS) and QOL of low back in terms of Roland-Morris Disability Questionnaire (RDQ). RESULTS: The ACP, TENS and A&T groups all reported lower VAS and RDQ scores. Significant reduction in pain intensity (P<0.008) and significant improvement in QOL (P<0.008) were shown in the A&T group. CONCLUSION: Combined acupuncture and TENS treatment is effective in pain relief and QOL of low back improvement for the sampled patients suffering from chronic LBP.

Effects of tender point acupuncture on delayed onset muscle soreness (DOMS)--a pragmatic trial.

BACKGROUND: Acupuncture is used to reduce inflammation and decrease pain in delayed onset muscle soreness (DOMS). This study investigates the efficacy of acupuncture on the symptoms of DOMS. METHODS: Thirty subjects were assigned randomly to there groups, namely the control, non-tender point and tender point groups. Measurement of pain with full elbow flexion was used as indices of efficacy. Measurements were taken before and after exercise, immediately after treatment and seven days after treatment. RESULTS: Significant differences in visual analog scores for pain were found between the control group and tender point group immediately after treatment and three days after exercise (P < 0.05, Dunnetts multiple test). CONCLUSION: The results show that tender point acupuncture relieves muscle pain of DOMS.

A pilot study on using acupuncture and transcutaneous electrical nerve stimulation (TENS) to treat knee osteoarthritis (OA).

BACKGROUND: The present study tests whether a combined treatment of acupuncture and transcutaneous electrical nerve stimulation (TENS) is more effective than acupuncture or TENS alone for treating knee osteoarthritis (OA). METHODS: Thirty-two patients with knee OA were randomly allocated to four groups. The acupuncture group (ACP) received only acupuncture treatment at selected acupoints for knee pain; the TENS group (TENS) received only TENS treatment at pain areas; the acupuncture and TENS group (A&T) received both acupuncture and TENS treatments; the control group (CT) received topical poultice (only when necessary). Each group received specific weekly treatment five times during the study. Outcome measures were pain intensity in a visual analogue scale (VAS) and knee function in terms of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). RESULTS: The ACP, TENS and A&T groups reported lower VAS and WOMAC scores than the control group. Significant reduction in pain intensity (P = 0.039) and significant improvement in knee function (P = 0.008) were shown in the A&T group. CONCLUSION: Combined acupuncture and TENS treatment was effective in pain relief and knee function improvement for the sampled patients suffering from knee OA.

Trigger point acupuncture for treatment of knee osteoarthritis--a preliminary RCT for a pragmatic trial.

BACKGROUND: There is evidence for the efficacy of acupuncture treatment in knee osteoarthritis, but it remains unclear which acupuncture modes are most effective. We evaluated the effects of trigger point acupuncture on pain and quality of life in knee osteoarthritis patients, compared with acupuncture at standard points, and sham acupuncture. METHODS: Thirty patients (27 women, 3 men; aged 61-82 years) with non-radiating knee osteoarthritis pain for at least six months and normal neurological examination were randomised to one of three groups for the study period of 21 weeks. Each group received five acupuncture treatment sessions. The standard acupuncture point group (n=10) received treatment at traditional acupuncture points for knee pain; the trigger point acupuncture group (n=10) received treatment at trigger points; and the third group (n=10) received sham acupuncture treatment at the trigger points. Outcome measures were pain intensity (visual analogue scale, VAS) and WOMAC index (Western Ontario and McMaster Universities Arthritis Index). The groups were compared by the area under the curve method. RESULTS: Five patients dropped out of the study because of lack of improvement, and one patient (in the trigger point acupuncture group) dropped out because of deterioration of symptoms; the remaining 24 patients were included in the analysis. After treatment, the trigger point acupuncture group reported less pain intensity on VAS than the standard acupuncture or sham treatment group, but both the trigger point acupuncture and standard acupuncture groups reported improvement of function of knee. There was a significant reduction in pain intensity between pre-treatment and five weeks after treatment for the trigger point acupuncture (P<0.01) and standard acupuncture groups (P<0.01) included in the analysis, but not for the sham treatment group. Group comparison using the area under the curves demonstrated a significant difference only between trigger point acupuncture and sham treatment groups analysed (P<0.025 for VAS, and P<0.031 for WOMAC). CONCLUSION: These results suggest that trigger point acupuncture therapy may be more effective for osteoarthritis of the knee in some elderly patients than standard acupuncture therapy.

Randomised trial of trigger point acupuncture compared with other acupuncture for treatment of chronic neck pain.

INTRODUCTION: There is some evidence for the efficacy of acupuncture in chronic neck pain (CNP) treatment, but it remains unclear which acupuncture modes are most effective. Objective was to evaluate the effects of trigger point acupuncture on pain and quality of life (QOL) in CNP patients compared to three other acupuncture treatments (acupoints, non-trigger point and sham treatment). METHODS: Forty out-patients (29 women, 11 men; age range: 47-80 years) from the Department of Orthopaedic Surgery, Meiji University of Oriental Medicine, with non-radiating CNP for at least 6 months and normal neurological examination were randomised to one of four groups over 13 weeks. Each group received two phases of acupuncture treatment with an interval between them. The acupoint group (standard acupuncture; SA, n=10) received treatment at traditional acupoints for neck pain, the trigger point (TrP, n=10) and non-trigger point (non-TrP, n=10) groups received treatment at tenderness points for the same muscle, while the other acupuncture group received sham treatments on the trigger point (SH, n=10). Outcome measures were pain intensity (visual analogue scale; VAS 0-100mm) and disease specific questionnaire (neck disability index; NDI, 60-point scale). RESULTS: After treatment, the TrP group reported less pain intensity and improved QOL compared to the SA or non-TrP group. There was significant reduction in pain intensity between the treatment and the interval for the TrP group (p<0.01, Dunnett's multiple test), but not for the SA or non-TrP group. CONCLUSION: These results suggest that trigger point acupuncture therapy may be more effective on chronic neck pain in aged patients than the standard acupuncture therapy.

Acupuncture for chronic pain in Japan: a review.

Many Japanese reports of acupuncture and moxibustion for chronic pain are not listed in medical databases such as Medline. Therefore, they are not easily accessible to researchers outside of Japan. To complement existing reviews of acupuncture and moxibustion for chronic pain and to provide more detailed discussion and analysis, we did a literature search using 'Igaku Chuo Zasshi Wed' (Japana Centra Revuo Medicina) and 'Citation Information by National Institute of Information' covering the period 1978-2006. Original articles and case reports of acupuncture and moxibustion treatment of chronic pain were included. Animal studies, surveys, and news articles were excluded. Two independent reviewers extracted data from located articles in a pre-defined structured way, and assessed the likelihood of causality in each case. We located 57 papers written in Japanese (20 full papers, 37 case reports). Conditions examined were headache (12 trials), chronic low back pain (9 trials), rheumatoid arthritis (8 trials), temporomandibular dysfunction (8 trials), katakori (8 trials) and others (12 trials). While 23 were described as clinical control trials (CCTs), 11 employed a quasi-random method. Applying the 5-point Jadad quality assessment scoring system, the mean score was 1.5 +/- 1.3 (SD). Eleven (52%) of the CCTs were conducted to determine a more effective procedure for acupuncture; these compared a certain type of acupuncture with another type of acupuncture or specific additional points. In particular, the trigger point acupuncture was widely used to treat chronic low back pain in Japan. Many reports of chronic pain treatment by acupuncture and moxibustion are listed in Japanese databases. From the data, we conclude that there is limited evidence that acupuncture is more effective than no treatment, and inconclusive evidence that trigger point acupuncture is more effective than placebo, sham acupuncture or standard care.

Effects of trigger point acupuncture on chronic low back pain in elderly patients--a sham-controlled randomised trial.

INTRODUCTION: There is some evidence for the efficacy of acupuncture, but it remains unclear whether trigger point acupuncture is effective. Our objective was to evaluate the effects of trigger point acupuncture on pain and quality of life in chronic low back pain patients compared with sham acupuncture. METHODS: Twenty-six consecutive out-patients (17 women, 9 men; age range: 65-91 years) from the Department of Orthopaedic Surgery, Meiji University of Oriental Medicine, with non-radiating low back pain for at least six months and normal neurological examination, were randomised to two groups. Each group received one phase of trigger point acupuncture and one of sham acupuncture with a three week washout period between them, over 12 weeks. Group A (n = 13) received trigger point acupuncture in the first phase and sham acupuncture in the second. Group B (n = 13) received the same interventions in the reverse order. Outcome measures were pain intensity (visual analogue scale, VAS) and Roland Morris Questionnaire. RESULTS: Nineteen patients were included in the analysis. At the end of the first treatment phase, group A receiving trigger point acupuncture scored significantly lower VAS (P < 0.001) and Roland Morris Questionnaire scores (P < 0.01) than the sham control group. There were significant within-group reductions in pain in both groups during the trigger point acupuncture phase but not in the sham treatment phase. However, the beneficial effects were not sustained. CONCLUSION: These results suggest that trigger point acupuncture may have greater short term effects on low back pain in elderly patients than sham acupuncture.

Influence of surface anesthesia on the pressure pain threshold measured with different-sized probes.

Transcutaneous pressure with pressure probes of arbitrary diameters have been commonly used for measuring the threshold and magnitude of muscle pain, yet this procedure lacks scientific validation. To examine the valid probe dimensions, we conducted physiological experiments using 34 human subjects. Pin-prick pain, pressure pain threshold (PPT) to pressure probes of various diameters, heat pain threshold, and electrical pain threshold of deep tissues were measured before and after application of surface lidocaine anesthesia to the skin surface over the brachioradial muscle in a double-blinded manner. The anesthesia neither affected PPT with larger probes (diameters: 1.6 and 15 mm) nor increased electric pain threshold of deep structures, whereas it diminished pain count in pin-prick test and PPT with a 1.0 mm diameter probe, suggesting that mechanical pain thresholds measured with 1.6 and 15 mm probes reflect the pain threshold of deep tissues, possibly muscle. Pain thresholds to heat did not change after application of the anesthesia. These results suggest that larger pressure probes can give a better estimation of muscular pain threshold.

A proposed experimental model of myofascial trigger points in human muscle after slow eccentric exercise.

BACKGROUND: The purpose of this study was to develop an experimental model of myofascial trigger points to investigate their pathophysiology. METHODS: Fifteen healthy volunteers who gave informed consent underwent repetitive eccentric exercise of the third finger of one hand (0.1 Hz repetitions, three sets at five minute intervals) until exhaustion. Physical examination, pressure pain threshold, and electrical pain threshold of the skin, fascia and muscle were measured immediately afterwards and for seven days. Needle electromyogram (EMG) was also recorded in a subgroup of participants. RESULTS: Pressure pain thresholds decreased to a minimum on the second day after the exercise, then gradually returned to baseline values by the seventh day. On the second day, a ropy band was palpated in the exercised forearm muscle and the electrical pain threshold of the fascia at the palpable band was the lowest among the measured loci and tissues. Needle EMG activity accompanied with dull pain sensation was recorded only when the electrode was located on or near the fascia of the palpable band on the second day of exercise. CONCLUSION: These results suggest that eccentric exercise may yield a useful model for the investigation of the myofascial trigger points and/or acupuncture points. The sensitised nociceptors at the fascia of the palpable band might be a possible candidate for the localised tender region.