Myofascial Trigger Spots Research Articles

Relationship between muscle spindles and myofascial trigger spots according to Hoffmann reflex pathway and tissue morphology characteristics in a rat model.

To determine how muscle spindles are involved in the pathophysiology of chronic myofascial trigger spots (MTrSs, similar to myofascial trigger points) in a rat injury model according to the characteristics of the Hoffmann reflex (H-reflex) and the anatomical relationship between muscle spindles and MTrSs. 16 male Sprague-Dawley rats (7 weeks old) were randomly divided into experimental and control groups. A blunt strike injury and eccentric exercise were applied to the gastrocnemius muscle of rats in the experimental group once a week for 8 weeks as a MTrS modelling intervention. Subsequently, the rats were reared normally and rested for 4 weeks. At the end of the 12th week, the rats were examined for the presence of MTrSs defined by the detection of a palpable taut band exhibiting both a local twitch response and spontaneous electrical activity. After modelling, evocation of the H-reflex and morphological examination of muscle spindles and MTrSs were conducted. The threshold (0.35±0.04 mA) of the H-reflex and latency (1.24±0.18 ms) of the M wave recorded at MTrSs were not significantly different to those at non-MTrSs (P>0.05). Compared with non-MTrSs, a lower Mmax (4.28±1.27 mV), higher Hmax (median (IQR) 0.95 (0.80-1.08) mV) and Hmax/Mmax (median (IQR) 0.21 (0.16-0.40)), and shorter H wave latency (4.60±0.89 ms) were recorded at MTrSs (P<0.05). Morphologically, there was a close anatomical relationship between the MTrS cells and the muscle spindles. Compared with normal muscles, the H-reflex myoelectrical activity was enhanced and some muscle spindles might have been influenced by active MTrSs. Thus, muscle spindles may play an important role in the pathological mechanism underlying myofascial trigger points.

Structural and functional abnormalities of motor endplates in rat skeletal model of myofascial trigger spots

Myofascial trigger points (MTrPs) are defined as hyperirritable spots in a palpable taut band (TB) of skeletal muscle fibers. Knowing the formation and location of MTrPs is a great help to prevent their development and inactivate existing MTrPs. This study aimed to obtain new evidence that myofascial trigger spots (MTrSs), which are similar to human MTrPs, are found in dysfunctional motor endplates by observing the morphological characteristics of muscles and changes in biochemical substances. A total of 32 male Sprague Dawley rats were randomly divided into four groups: two control groups (i.e., C1 and C2) and two model groups (i.e., M1 and M2). C1 and M1 were used for acetylcholine (ACh) content measurement, while C2 and M2 were utilized for acetylcholinesterase (AChE) staining. In the model groups, blunt striking injury was induced and eccentric exercise was applied to the left gastrocnemius for 8 weeks. After 1 month, spontaneous electrical activity(SEA), AChE optical density (OD), muscle fiber diameter, and ACh content were measured. The results showed that extensive abnormal endplate noise (aEPN), including positive neurons, fibrillation potentials, fasciculation potential, and high amplitude (endplate spikes [EPS]), is present at MTrSs in M1. Quantitative electromyography results showed that the amplitudes of aEPN and frequency of EPS in M1 were significantly higher than those of C1. The ACh content of MTrSs in M1 was significantly higher than that in C1. The AChE OD value of M2 was significantly lower than that of C2. In addition, the diameter of the muscle fibers in the AChE-stained area was longer in M2 than in C2. In conclusion, MTrSs formed at the motor endplate with a larger diameter of muscle fibers. Excessive ACh release and decreased AChE activity at MTrSs stimulated muscle action potential and muscle contraction.

Decreased Spontaneous Electrical Activity and Acetylcholine at Myofascial Trigger Spots after Dry Needling Treatment: A Pilot Study.

Objective The aims of this study are to investigate the changes in spontaneous electrical activities (SEAs) and in acetylcholine (ACh), acetylcholine receptor (AChR), and acetylcholine esterase (AChE) levels after dry needling at myofascial trigger spots in model rats. Materials and Methods Forty-eight male Sprague-Dawley rats were divided into four groups. Thirty-six rats were assigned to three model groups, which underwent MTrSs modeling intervention. Twelve rats were assigned to the blank control (BC) group. After model construction, the 36 model rats were randomly subdivided into three groups according to treatment: MTrSs model control (MC) and two dry needling groups. One dry needling group received puncturing at MTrSs (DN-M), whereas the other underwent puncturing at non-MTrSs (DN-nM). Dry needling treatment will last for two weeks, once a week. SEAs and ACh, AChR, and AChE levels were measured after one-week rest of dry needling treatment. Results The amplitudes and frequencies of endplate noise (EPN) and endplate spike (EPS) significantly decreased after dry needling treatment in the DN-M group. Moreover, ACh and AChR levels significantly decreased, whereas AChE significantly increased after dry needling treatment in the DN-M group. Conclusion Dry needling at the exact MTrSs is more effective than dry needling at non-MTrSs.

Acupuncture at distant myofascial trigger spots enhances endogenous opioids in rabbits: a possible mechanism for managing myofascial pain.

Acupuncture applied at myofascial trigger points (MTrPs) of distant anatomical regions, to reduce pain in a patient's area of primary complaint, is one strategy that is available to manage myofascial pain. However, the endogenous opioid-mediated analgesic mechanism of distant acupuncture associated with pain control is still unclear. This aims of this study were to evaluate the changes in enkephalin and β-endorphin in serum, spinal cord, dorsal root ganglion (DRG) and muscle induced by acupuncture at distant myofascial trigger spots (MTrSs, similar to human MTrPs) in rabbits, to explore its underlying remote analgesic mechanism. Acupuncture at MTrSs of a distant muscle (gastrocnemius) was performed either for one session or five daily sessions in rabbits. The levels of enkephalin and β-endorphin in proximal muscle (biceps femoris), serum, DRGs and spinal cords (L5-S2) were then determined by immunoassay immediately and 5 days after treatment. Immediately after treatment, acupuncture comprising both one dose and five doses significantly enhanced spinal enkephalin expression and serum β-endorphin levels (p<0.05). However, only five-dose acupuncture significantly enhanced the β-endorphin levels in the biceps femoris and DRGs (p<0.05), while 1-dose acupuncture did not (p>0.05). Furthermore, 5 days after treatment, significantly increased levels of spinal enkephalin and serum β-endorphin persisted in animals that received 5-dose acupuncture (p<0.05). This study demonstrates that interactions within the endogenous opioid system may be involved in the remote effects of acupuncture treatment and could be a potential analgesic mechanism underlying MTrP pain management.

A afferent fibers are involved in the pathology of central changes in the spinal dorsal horn associated with myofascial trigger spots in rats.

A afferent fibers have been reported to participate in the development of the central sensitization induced by inflammation and injuries. Current evidence suggests that myofascial trigger points (MTrPs) induce central sensitization in the related spinal dorsal horn, and clinical studies indicate that A fibers are associated with pain behavior. Because most of these clinical studies applied behavioral indexes, objective evidence is needed. Additionally, MTrP-related neurons in dorsal root ganglia and the spinal ventral horn have been reported to be smaller than normal, and these neurons were considered to be related to A fibers. To confirm the role of A fibers in MTrP-related central changes in the spinal dorsal horn, we studied central sensitization as well as the size of neurons associated with myofascial trigger spots (MTrSs, equivalent to MTrPs in humans) in the biceps femoris muscle of rats and provided some objective morphological evidence. Cholera toxin B subunit-conjugated horseradish peroxidase was applied to label the MTrS-related neurons, and tetrodotoxin was used to block A fibers specifically. The results showed that in the spinal dorsal horn associated with MTrS, the expression of glutamate receptor (mGluR1α/mGluR5/NMDAR1) increased, while the mean size of MTrS-related neurons was smaller than normal. After blocking A fibers, these changes reversed to some extent. Therefore, we concluded that A fibers participated in the development and maintenance of the central sensitization induced by MTrPs and were related to the mean size of neurons associated with MTrPs in the spinal dorsal horn.

The Effect of Monochromatic Infrared Photo Energy on the Irritability of Myofascial Trigger Spot of Rabbit Skeletal Muscle.

Objective. To determine whether the vasodilatation effect of monochromatic infrared photo energy (MIRE) had the potential for the treatment of myofascial trigger spot (MTrS) in rabbits. Design. A randomized-controlled animal study. Subjects. Twelve adult New Zealand rabbits. Methods. For each rabbit, a MTrS (equivalent to a myofascial trigger point in humans) in one side of the biceps femoris muscle was randomly selected for MIRE treatment (experimental side), while another MTrS in the other side (control side) received a sham treatment. The intervention consisted of a daily 40 minutes treatment, three times per week for 2 weeks. The prevalence of endplate noise (EPN) loci in the MTrS was assessed before, immediately after, and one week after the completion of the 2-week treatment. Results. MIRE could suppress the prevalence of EPN in the MTrS. The degree of reduction in EPN prevalence in the MTrS between the experimental side and the control side was significantly different immediately after MIRE treatment, but not significantly different one week after MIRE treatment. Conclusion. Our study suggests that MIRE may be a useful therapeutic option for the management of the myofascial trigger point in humans.

Myelinated Afferents Are Involved in Pathology of the Spontaneous Electrical Activity and Mechanical Hyperalgesia of Myofascial Trigger Spots in Rats.

Myofascial trigger points (MTrPs) are common causes for chronic pain. Myelinated afferents were considered to be related with muscular pain, and our clinical researches indicated they might participate in the pathology of MTrPs. Here, we applied myofascial trigger spots (MTrSs, equal to MTrPs in human) of rats to further investigate role of myelinated afferents. Modified pyridine-silver staining revealed more nerve endings at MTrSs than non-MTrSs (P < 0.01), and immunohistochemistry with Neurofilament 200 indicated more myelinated afferents existed in MTrSs (P < 0.01). Spontaneous electrical activity (SEA) recordings at MTrSs showed that specific block of myelinated afferents in sciatic nerve with tetrodotoxin (TTX) led to significantly decreased SEA (P < 0.05). Behavioral assessment showed that mechanical pain thresholds (MPTs) of MTrSs were lower than those of non-MTrSs (P < 0.01). Block of myelinated afferents by intramuscular TTX injection increased MPTs of MTrSs significantly (P < 0.01), while MPTs of non-MTrSs first decreased (P < 0.05) and then increased (P > 0.05). 30 min after the injection, MPTs at MTrSs were significantly lower than those of non-MTrSs (P < 0.01). Therefore, we concluded that proliferated myelinated afferents existed at MTrSs, which were closely related to pathology of SEA and mechanical hyperalgesia of MTrSs.

Fluence-dependent effects of low-level laser therapy in myofascial trigger spots on modulation of biochemicals associated with pain in a rabbit model.

Evidence strongly supports that low-level laser therapy (LLLT) is an effective physical modality for the treatment of pain associated with myofascial trigger points (MTrP). However, the effect of laser fluence (energy intensity in J/cm(2)) on biochemical regulation related to pain is unclear. To better understand the biochemical mechanisms modulated by high- and low-fluence LLLT at myofascial trigger spots (MTrSs; similar to human MTrPs) in skeletal muscles of rabbits, the levels of β-endorphin (β-ep), substance P (SP), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2) were investigated in this study. New Zealand rabbits (2.5-3.0 kg in weight) were used in this study. High-fluence LLLT (27 J/cm(2)), low-fluence LLLT (4.5 J/cm(2)), or sham operations were applied on MTrSs of biceps femoris of rabbits for five sessions (one session per day). Effects of LLLT at two different fluences on biceps femoris, dorsal root ganglion (DRG), and serum were determined by β-ep, SP, TNF-α, and COX-2 immunoassays. LLLT irradiation with fluences of 4.5 and 27 J/cm(2) at MTrSs can significantly reduce SP level in DRG. LLLT with lower fluence of 4.5 J/cm(2) exerted lower levels of TNF-α and COX-2 expression in laser-treated muscle, but LLLT with higher fluence of 27 J/cm(2) elevated the levels of β-ep in serum, DRG, and muscle. This study demonstrated fluence-dependent biochemical effects of LLLT in an animal model on management of myofascial pain. The findings can contribute to the development of dosage guideline for LLLT for treating MTrP-induced pain.

Remote Dose-Dependent Effects of Dry Needling at Distant Myofascial Trigger Spots of Rabbit Skeletal Muscles on Reduction of Substance P Levels of Proximal Muscle and Spinal Cords

Background. Dry needling at distant myofascial trigger points is an effective pain management in patients with myofascial pain. However, the biochemical effects of remote dry needling are not well understood. This study evaluates the remote effects of dry needling with different dosages on the expressions of substance P (SP) in the proximal muscle, spinal dorsal horns of rabbits. Methods. Male New Zealand rabbits (2.5–3.0 kg) received dry needling at myofascial trigger spots of a gastrocnemius (distant muscle) in one (1D) or five sessions (5D). Bilateral biceps femoris (proximal muscles) and superficial laminaes of L5-S2, T2-T5, and C2-C5 were sampled immediately and 5 days after dry needling to determine the levels of SP using immunohistochemistry and western blot. Results. Immediately after dry needling for 1D and 5D, the expressions of SP were significantly decreased in ipsilateral biceps femoris and bilateral spinal superficial laminaes (P < .05). Five days after dry needling, these reduced immunoactivities of SP were found only in animals receiving 5D dry needling (P < .05). Conclusions. This remote effect of dry needling involves the reduction of SP levels in proximal muscle and spinal superficial laminaes, which may be closely associated with the control of myofascial pain.

Needling Therapy for Myofascial Pain Control

Needling Therapy for Myofascial Pain Control

Dry Needling at Myofascial Trigger Spots of Rabbit Skeletal Muscles Modulates the Biochemicals Associated with Pain, Inflammation, and Hypoxia

Background and Purpose. Dry needling is an effective therapy for the treatment of pain associated with myofascial trigger point (MTrP). However, the biochemical effects of dry needling that are associated with pain, inflammation, and hypoxia are unclear. This study investigated the activities of β-endorphin, substance P, TNF-α, COX-2, HIF-1α, iNOS, and VEGF after different dosages of dry needling at the myofascial trigger spots (MTrSs) of a skeletal muscle in rabbit. Materials and Methods. Dry needling was performed either with one dosage (1D) or five dosages (5D) into the biceps femoris with MTrSs in New Zealand rabbits. Biceps femoris, serum, and dorsal root ganglion (DRG) were sampled immediately and 5 d after dry needling for β-endorphin, substance P, TNF-α, COX-2, HIF-1α, iNOS, and VEGF immunoassays. Results. The 1D treatment enhanced the β-endorphin levels in the biceps femoris and serum and reduced substance P in the biceps femoris and DRG. The 5D treatment reversed these effects and was accompanied by increase of TNF-α, COX-2, HIF-1α, iNOS, and VEGF production in the biceps femoris. Moreover, the higher levels of these biochemicals were still maintained 5 d after treatment. Conclusion. Dry needling at the MTrSs modulates various biochemicals associated with pain, inflammation, and hypoxia in a dose-dependent manner.

Remote Subcutaneous Needling to Suppress the Irritability of Myofascial Trigger Spots: An Experimental Study in Rabbits

Objective. To obtain electrophysiological effects of Fu's subcutaneous needling (FSN) on needling distance by assessment of endplate noise (EPN) recorded from the myofascial trigger spots (MTrSs) in rabbit skeletal muscle. Method. Eighteen New Zealand rabbits weighing 2.5–3.0 kg were randomly divided into two groups as follows: proximal needling (PN) group and distal needling (DN) group. The needling procedure followed the instructions described by the inventor of FSN, including needling insertion and swaying movement. The amplitudes of EPN on the MTrS region of BF muscle were recorded as an index of MTrS irritability. Random sampling of EPN tracings were taken for further analyses before, during, and after FSN treatment. Results. In PN and DN groups, the trends of EPN amplitude alterations were similar at conditions before, during, and after FSN treatment. The degree of reduction in the EPN amplitude in PN group was significantly higher than that in DN group. There were no significant changes in EPN amplitudes in the MTrS of contralateral BF without FSN intervention either in DN or PN group. Conclusion. The irritability of proximal MTrSs could be modulated after ipsilateral FSNs. The placement of FSN may affect the effectiveness of suppression of irritability of MTrSs.

Spinal Cord Mechanism Involving the Remote Effects of Dry Needling on the Irritability of Myofascial Trigger Spots in Rabbit Skeletal Muscle

Hsieh Y-L, Chou L-W, Joe Y-S, Hong C-Z. Spinal cord mechanism involving the remote effects of dry needling on the irritability of myofascial trigger spots in rabbit skeletal muscle. Objective To elucidate the neural mechanisms underlying the remote effects produced by dry needling rabbit skeletal muscle myofascial trigger spots (MTrSs) via analyses of their endplate noise (EPN) recordings. Design Experimental animal controlled trial. Setting An animal laboratory of a university. Animals Male New Zealand rabbits (N=96) (body weight, 2.5–3.0kg; age, 16–20wk). Intervention Animals received no intervention for neural interruption in group I, transection of the tibial nerve in group II, transection of L5 and L6 spinal cord in group III, and transection of the T1 and T2 spinal cord in group IV. Each group was further divided into 4 subgroups: animals received ipsilateral dry needling, contralateral dry needling, ipsilateral sham needling, or contralateral sham needling of gastrocnemius MTrSs. Main Outcome Measures EPN amplitudes of biceps femoris (BF) MTrSs. Results BF MTrS mean EPN amplitudes significantly increased ( P<.05) initially after gastrocnemius verum needling but reduced to a level significantly lower ( P<.05) than the preneedling level in groups I and IV with ipsilateral dry needling or contralateral dry needling, and in group II with contralateral dry needling (but not ipsilateral dry needling). No significant EPN amplitude changes were observed in BF MTrS in group III or in the control animals receiving superficial needling (sham). Conclusion This remote effect of dry needling depends on an intact afferent pathway from the stimulating site to the spinal cord and a normal spinal cord function at the levels corresponding to the innervation of the proximally affected muscle.

Dose-dependent and Ceiling Effects of Therapeutic Laser on Myofascial Trigger Spots in Rabbit Skeletal Muscles

ABSTRACTObjective: To evaluate the effect of low-level laser treatment with different dosages on the irritability of myofascial trigger spots [MTrS] in rabbit skeletal muscles.Methods: Twenty rabbits were equally divided into a low dose group and a high dose group. In each rabbit, the MTrS on the experimental side was irradiated with 660-nm continuous-wave gallium-aluminum-arsenate laser daily for six sessions. The energy per session was 27 J/cm2 [low dose group] and 72 J/cm2 [high dose group]. The MTrS on the other side received sham treatment. The MTrS irritability was assessed with the prevalence of endplate noise [EPN] at baseline after the first and after the last treatments.Results: After the first laser treatment, the EPN prevalence was significantly decreased in both groups. The percentage change in the high dose group was greater than that in the low dose group. The EPN prevalence after the last laser treatment was lower than that after the first laser treatment in the low dose group, but not in ...

Electrophysiologic Effects of a Therapeutic Laser on Myofascial Trigger Spots of Rabbit Skeletal Muscles

To better understand the mechanisms of therapeutic lasers for treating human myofascial trigger points, we designed a blinded controlled study of the effects of a therapeutic laser on the prevalence of endplate noise (EPN) recorded from the myofascial trigger spot (MTrS) of rabbit skeletal muscle. In eight rabbits, one MTrS in each biceps femoris muscle was irradiated with a 660-nm, continuous-wave, gallium-aluminum-arsenate (GaAlAs) laser, at 9 J/cm2. The contralateral side of muscle was treated with a sham laser. Each rabbit received six treatments. The immediate and cumulative effects were assessed by the prevalence of EPN with electromyographic (EMG) recordings after the first and last treatments. Compared with pretreatment values, the percentages of EPN prevalence in the experimental side after the first and last treatments were significantly reduced (P < 0.01 for both). The change in EPN prevalence in the experimental side was significantly greater than in the control side immediately after the first and last treatments (P < 0.05). However, no significant differences were noted between the first and last treatments (P > 0.05). In our study, immediate and cumulative effects of a GaAlAs laser applied on MTrS were demonstrated on the basis of the assessment of EPN prevalence. It seems that laser irradiation may inhibit the irritability of an MTrS in rabbit skeletal muscle. This effect may be a possible mechanism for myofascial pain relief with laser therapy.

The spinal cord connections of the myofascial trigger spots

Background Recent electrophysiological studies revealed that endplate noise (EPN) could be specifically recorded from a myofascial trigger point (MTrP) region. EPN has been considered as the focal graded potentials due to excessive acetylcholine release in neuromuscular junction. A recent histological study has demonstrated a free nerve ending at the vicinity of the site, from where EPN could be recorded in an MTrP region. However, the sensory (afferent) and the motor (efferent) connections between an MTrP and the spinal cord still has never been fully studied. Aims The aim of this study was to delineate both motor and sensory connections between an MTrP and the spinal cord by applying the stain with horseradish peroxidase (HRP). Methods Nine Wistar rats were studied. When the rat was anesthetized, its biceps femoris muscles were exposed for localizing the myofascial trigger spot (MTrS, equivalent to MTrP in human). In one side, a monopolar Teflon-coated, hollow-needle electrode was used for searching EPN in an MTrS region, and then HRP was injected via this hollow-needle electrode into the site where EPN was recorded. HRP was also injected into a normal (non-taut band, non-MTrS) site in the contralateral side to obtain the control data. Two days after HRP injection, the rats were sacrificed and their spinal cords and dorsal root ganglia (DRG) were sectioned for the identification of the sites where neurons were labeled with HRP. Results The HRP-labeled neurons were found in the ventral horn of the spinal cord and in the DRG over L3, L4, and L5, while most were found in the L5 level. The mean numbers of HRP-labeled neurons in the EPN side looked smaller than that in the control side, but the difference did not reach statistically significant level ( P > 0.05). The mean values of the diameters of the HRP-labeled neurons in the DRG were not significantly different between the EPN side and the control side ( P > 0.05). However, HRP-neurons in the ventral horn of the spinal cord in the EPN side showed mild tendency to be smaller than that in the control side. Conclusions The spinal cord connections of an MTrS are basically similar to that for a normal tissue region. The motor neurons related to MTrS tended to be smaller in their diameters. The findings in this study further supported the previously proposed hypotheses for the pathogenesis of an MTrP.

Effects of a calcium channel blocker on electrical activity in myofascial trigger spots of rabbits.

This study investigated the effect of a calcium channel blocking agent, verapamil, on the spontaneous electrical activity (SEA) in a myofascial trigger spot of biceps femoris muscles of rabbits. Left and right legs of eight adult New Zealand rabbits were randomly assigned into either experimental or control groups to assess the effect of verapamil on SEA. Verapamil and normal saline were injected into the external iliac artery for experimental and control groups, respectively. The experiment was divided into two phases: Phase A investigated the immediate effect of verapamil on SEA of one active locus, and phase B studied the effect of verapamil on SEA of 25 different active loci. The average integrated value of SEA was used to statistically analyze the effect of verapamil on myofascial trigger-spot sensitivity. In phase A, conducted on one active locus, the regression analysis results showed that the average integrated value in the verapamil group linearly decreased with time, but the average integrated value did not significantly change with time in the control group. In phase B, which analyzed 25 different active loci, the results indicated that the mean average integrated values in the verapamil group was significantly lower than that of the control group. Calcium channel blockers can effectively inhibit the SEA of myofascial trigger spots.

Inhibitory effect of dry needling on the spontaneous electrical activity recorded from myofascial trigger spots of rabbit skeletal muscle.

Dry needling of myofascial trigger points can relieve myofascial pain if local twitch responses are elicited during needling. Spontaneous electrical activity (SEA) recorded from an active locus in a myofascial trigger point region has been used to assess the myofascial trigger point sensitivity. This study was to investigate the effect of dry needling on SEA. Nine adult New Zealand rabbits were studied. Dry needling with rapid insertion into multiple sites within the myofascial trigger spot region was performed to the biceps femoris muscle to elicit sufficient local twitch responses. Very slow needle insertion with minimal local twitch response elicitation was conducted to the other biceps femoris muscle for the control study. SEA was recorded from 15 different active loci of the myofascial trigger spot before and immediately after treatment for both sides. The raw data of 1-sec SEA were rectified and integrated to calculate the average integrated value of SEA. Seven of nine rabbits demonstrated significantly lower normalized average integrated value of SEA in the treatment side compared with the control side (P < 0.05). The results of two-way analysis of variance show that the mean of the normalized average integrated value of SEA in the treatment group (0.565 +/- 0.113) is significantly (P < 0.05) lower than that of the control (0.983 +/- 0.121). Dry needling of the myofascial trigger spot is effective in diminishing SEA if local twitch responses are elicited. The local twitch response elicitation, other than trauma effects of needling, seems to be the primary inhibitory factor on SEA during dry needling.

The Effect of Transection of Innervating Nerve on Spontaneous Electrical Activity of Myofascial Trigger Spot in Rabbit Skeletal Muscle

The Effect of Transection of Innervating Nerve on Spontaneous Electrical Activity of Myofascial Trigger Spot in Rabbit Skeletal Muscle

No Increased Neuromuscular Jitter at Rabbit Skeletal Muscle Trigger Spot Spontaneous Electrical Activity Sites

Objective: One of the important characteristics of myofascial trigger point [MTrP] is spontaneous electrical activity [SEA]. Spontaneous electrical activity is recorded from an active locus [a basic unit] of MTrP and has been considered as an abnormal endplate potential, which might be due to excessive acetylcholine release in neuromuscular junction. This study is designed to test the hypothesis that active loci in MTrPs are related to neuromuscular transmission disorder.Methods: Twenty-one adult New Zealand rabbits were anesthetized and their biceps femoris were exposed to localize myofascial trigger spot [MTrS, equivalent to MTrP in human]. A monopolar needle electrode was first used for searching SEA in an MTrS region. Then, a single fiber electromyography [SFEMG] electrode was used to collect the neuromuscular jitter at the site where SEA was recorded. The same procedure was performed at the normal muscle site [no SEA recorded] in contralateral limb to collect the neuromuscular jitter as a control. Me...