Effects of Spray and Stretch on Postneedling Soreness and Sensitivity After Dry Needling of a Latent Myofascial Trigger Point

Objectives

To investigate (1) the effect of spray and stretch versus control on reducing postneedling soreness of 1 latent myofascial trigger point (MTrP) and (2) whether higher levels of psychological distress are associated with increased postneedling pain intensity.

Design

A 72-hour follow-up, single-blind randomized controlled trial.

Setting

University community.

Participants

Healthy volunteers (N=70; 40 men, 30 women) aged 18 to 36 years (mean age, 21±4y) with latent MTrP in 1 upper trapezius muscle.

Intervention

All subjects received a dry needling application over the upper trapezius muscle. Then, participants were randomly divided into 2 groups: an intervention group, which received spray and stretch over the needled trapezius muscle, and a control group, which did not receive any intervention.

Main Outcome Measures

Visual analog scale (at postneedling, posttreatment, and 6, 12, 24, 48, and 72h after needling), pressure pain threshold (at preneedling, postneedling, and 24 and 48h after needling). Psychological distress was evaluated by using the Symptom Checklist-90-Revised.

Results

Repeated-measures analysis of variance demonstrated a significant interaction between group and time (F_3,204.8=3.19; P<.05; η_p²=.04) for changes in postneedling soreness. Between-group differences were significant only immediately after intervention (P=.002), and there were no differences found between groups after 6 hours of the intervention (P>.05). Repeated measures of covariance showed that none of the psychological covariates affected these results. Somatization, anxiety, interpersonal sensitivity, and hostility were significantly correlated (P<.05) with postneedling pain intensity. Repeated-measures analysis of variance did not show a significant effect of spray and stretch on mechanical hyperalgesia (F_2.6,175=1.9; P=.131; η_p²=.02).

Conclusions

The spray and stretch had a short-term (<6h) effect in reducing postneedling soreness of a latent MTrP. Pressure pain threshold did not significantly change after spray and stretch. Psychological factors are related to postneedling pain.     

Effects of Deep Cervical Flexor Training on Pressure Pain Thresholds Over Myofascial Trigger Points in Patients With Chronic Neck Pain

Objective

The purpose of this study was to assess the effects of a low-load training program for the deep cervical flexors (DCFs) on pain, disability, and pressure pain threshold (PPT) over cervical myofascial trigger points (MTrPs) in patients with chronic neck pain.

Methods

Thirty patients with chronic idiopathic neck pain participated in a 6-week program of specific training for the DCF, which consisted of active craniocervical flexion performed twice per day (10-20 minutes) for the duration of the trial. Perceived pain and disability (Neck Disability Index, 0-50) and PPT over MTrPs of the upper trapezius, levator scapulae, and splenius capitis muscles were measured at the beginning and end of the training period.

Results

After completion of training, there was a significant reduction in Neck Disability Index values (before, 18.2 ± 12.1; after, 13.5 ± 10.6; P < .01). However, no significant changes in PPT were observed over the MTrPs.

Conclusion

Patients performing DCF training for 6 weeks demonstrated reductions in pain and disability but did not show changes in pressure pain sensitivity over MTrPs in the splenius capitis, levator scapulae, or upper trapezius muscles.     

Effects of burst-type transcutaneous electrical nerve stimulation on cervical range of motion and latent myofascial trigger point pain sensitivity

Rodríguez-Fernández AL, Garrido-Santofimia V, Güeita-Rodríguez J, Fernández-de-las-Peñas C. Effects of burst-type transcutaneous electrical nerve stimulation on cervical range of motion and latent myofascial trigger point pain sensitivity.

Objective

To assess the effects of a burst application of transcutaneous electrical nerve stimulation (TENS) on cervical range of motion and pressure point sensitivity of latent myofascial trigger points (MTrPs).

Design

A single-session, single-blind randomized trial.

Setting

General community rehabilitation clinic.

Participants

Individuals (N=76; 45 men, 31 women) aged 18 to 41 years (mean ± SD, 23±4y) with latent MTrPs in 1 upper trapezius muscle.

Interventions

Subjects were randomly divided into 2 groups: a TENS group that received a burst-type TENS (pulse width, 200μs; frequency, 100Hz; burst frequency, 2Hz) stimulation over the upper trapezius for 10 minutes, and a placebo group that received a sham-TENS application over the upper trapezius also for 10 minutes.

Main Outcome Measures

Referred pressure pain threshold (RPPT) over the MTrP and cervical range of motion in rotation were assessed before, and 1 and 5 minutes after the intervention by an assessor blinded to subjects' treatment.

Results

The analysis of covariance revealed a significant group × time interaction (P<.001) for RPPT: the TENS group exhibited a greater increase compared with the control group; however, between-group differences were small at 1 minute (0.3kg/cm²; 95% confidence interval [CI], 0.1–0.4) and at 5 minutes (0.6kg/cm²; 95% CI, 0.3–0.8) after treatment. A significant group × time interaction (P=.01) was also found for cervical rotation in favor of the TENS group. Between-group differences were also small at 1 minute (2.0°; 95% CI, 1.0–2.8) and at 5 minutes (2.7°; 95% CI, 1.7–3.8) after treatment.

Conclusions

A 10-minute application of burst-type TENS increases in a small but statistically significant manner the RPPT over upper trapezius latent MTrPs and the ipsilateral cervical range of motion.     

Remote Influences of Acupuncture on the Pain Intensity and the Amplitude Changes of Endplate Noise in the Myofascial Trigger Point of the Upper Trapezius Muscle

Chou L-W, Hsieh Y-L, Kao M-J, Hong C-Z. Remote influences of acupuncture on the pain intensity and the amplitude changes of endplate noise in the myofascial trigger point of the upper trapezius muscle.

Objective

To investigate the remote effect of acupuncture on the pain intensity and the endplate noise (EPN) recorded from a myofascial trigger point (MTrP) of the upper trapezius muscle.

Design

Randomized controlled trial.

Setting

University hospital.

Participants

Patients (N=20) with active MTrPs in upper trapezius muscles and no experience in acupuncture therapy.

Interventions

Patients were divided into 2 groups. Those in the control group received sham acupuncture, and those in the acupuncture group received modified acupuncture therapy with needle insertion into multiple loci to elicit local twitch responses. The acupuncture points of Wai-guan and Qu-chi were treated.

Main Outcome Measures

Subjective pain intensity (numerical pain rating scale) and mean EPN amplitude in the MTrP of the upper trapezius muscle.

Results

The pain intensity in the MTrP was significantly reduced after remote acupuncture (from 7.4±0.8 to 3.3±1.1; P<.001), but not after sham acupuncture (from 7.4±0.8 to 7.1±0.9; P>.05). The mean EPN amplitude was significantly lower than the pretreatment level after acupuncture treatment (from 21.3±9.5μV to 9.5±3.5μV; P<.01), but not after sham acupuncture treatment (from 19.6±7.6μV to 19.3±7.8μV; P>.05). The change in the pain intensity was significantly correlated with the change of EPN amplitude (r = 0.685).

Conclusions

Both subjective changes in the pain intensity and objective changes of the EPN amplitude in the MTrP region of the upper trapezius muscle were found during and after acupuncture treatment at the remote ipsilateral acupuncture points. This study may further clarify the physiological basis of the remote effectiveness of acupuncture therapy for pain control.     

Intra-rater reliability of an experienced physiotherapist in locating myofascial trigger points in upper trapezius muscle

Objectives:

Myofascial trigger points (MTrPs) are considered the principal clinical feature of myofascial pain syndrome (MPS). An MTrP consists of spot tenderness within a taut band of muscle fibers and its stimulation can produce both local and referred pain. The clinical diagnosis of MPS depends on correct history taking and a physical examination aimed at identifying the presence of MTrP. The purpose of this study was to investigate the intra-rater reliability of a palpation protocol used for locating an MTrP in the upper trapezius muscle.

Methods:

Twenty-four subjects with MTrP in the upper trapezius muscle were examined by an experienced physiotherapist. During each of eight experimental sessions, subjects were examined twice in randomized order using a palpation protocol. An anatomical landmark system was defined and the MTrP location established using X and Y values.

Results:

The intraclass correlation coefficient ICC_(1,1) values were 0.62 (95% CI: 0.30–0.81) for X and 0.81 (95% CI: 0.61–0.91) for Y. The Bland–Altman plots for X and Y showed a mean of difference of 0.04 and −0.2 mm, respectively. Limits of agreement for X ranged from −26.3 to 26.2 mm and for Y from −27 to 26.4 mm.

Discussion:

The ICC_(1,1) for the observed values revealed a moderate to high correlation and the Bland–Altman analysis showed means of difference very close to zero with narrow limits of agreement. An experienced physiotherapist can reliably identify MTrP locations in upper trapezius muscle using a palpation protocol.     

Quantification of Dry Needling and Posture Effects on Myofascial Trigger Points Using Ultrasound Shear-Wave Elastography

Objectives

To determine (1) whether the shear modulus in upper trapezius muscle myofascial trigger points (MTrPs) reduces acutely after dry needling (DN), and (2) whether a change in posture from sitting to prone affects the shear modulus.

Design

Ultrasound images were acquired in B mode with a linear transducer oriented in the transverse plane, followed by performance of shear-wave elastography (SWE) before and after DN and while sitting and prone.

Setting

University.

Participants

Women (N=7; mean age ± SD, 46±17y) with palpable MTrPs were recruited.

Intervention

All participants were dry needled in the prone position using solid filament needles that were inserted and manipulated inside the MTrPs. SWE was performed before and after DN in the sitting and prone positions.

Main Outcome Measure

MTrPs were evaluated by shear modulus using SWE.

Results

Palpable reductions in stiffness were noted after DN and in the prone position. These changes were apparent in the shear modulus map obtained with ultrasound SWE. With significant main effects, the shear modulus reduced from before to after DN (P<.01) and from the sitting to the prone position (P<.05). No significant interaction effect between time and posture was observed.

Conclusions

The shear modulus measured with ultrasound SWE reduced after DN and in the prone position compared with sitting, in agreement with reductions in palpable stiffness. These findings suggest that DN and posture have significant effects on the shear modulus of MTrPs, and that shear modulus measurement with ultrasound SWE may be sensitive enough to detect these effects.     

Attenuated Skin Blood Flow Response to Nociceptive Stimulation of Latent Myofascial Trigger Points

Zhang Y, Ge H-Y, Yue S-W, Kimura Y, Arendt-Nielsen L. Attenuated skin blood flow response to nociceptive stimulation of latent myofascial trigger points.

Objectives

To investigate the effect of painful stimulation of latent myofascial trigger points (MTrPs) on skin blood flow and to evaluate the relative sensitivity of laser Doppler flowmetry (LDF) and thermography in the measurement of skin blood flow.

Design

Painful stimulation was obtained by a bolus injection of glutamate (0.1mL, 0.5M) into a latent MTrP located in the right or left brachioradialis muscles. A bolus of glutamate injection into a non-MTrP served as control. Pain intensity (visual analog scale [VAS]) was assessed after glutamate injection. Pressure pain threshold (PPT) was recorded bilaterally in the brachioradialis muscle before and after glutamate-induced pain. Skin blood flow and surface skin temperature were measured bilaterally in the forearms before, during, and after glutamate-induced pain with LDF and thermography.

Setting

A biomedical research facility.

Participants

Fifteen healthy volunteer subjects.

Interventions

Not applicable.

Main Outcome Measures

VAS, PPT, skin blood flow, and surface skin temperature.

Results

Glutamate injection into latent MTrPs induced higher pain intensity (F=7.16; P<.05) and lower PPT (F=11.41, P<.005) than into non-MTrPs. Glutamate injection into non-MTrPs increased skin blood flow bilaterally in the forearms, but skin blood flow after glutamate injection into latent MTrPs was significantly less increased at the local injection area or decreased at distant areas compared with non-MTrPs (all P<.05). Skin temperature was not affected after glutamate injection into either latent MTrPs or non-MTrPs (all P>.05).

Conclusions

The present study demonstrated an attenuated skin blood flow response after painful stimulation of latent MTrPs compared with non-MTrPs, suggesting increased sympathetic vasoconstriction activity at latent MTrPs. Additionally, LDF was more sensitive than thermography in the detection of the changes in skin blood flow after intramuscular nociceptive stimulation.     

Instrument-assisted soft tissue mobilization increases myofascial trigger point pain threshold

Background

A myofascial trigger point (MTrP) has been defined as a hyperirritable, palpable nodule in a skeletal muscle. The signs and symptoms of a MTrP include muscle pain, weakness, and dysfunction. MTrPs are common problems associated with soft tissue pathology. Having an intervention to decrease MTrP pain can be clinically valuable.

Influence of calcaneus angle and muscle forces on strain distribution in the human Achilles tendon

Background

Heterogeneous distribution of tendon strain is considered to contribute to the development of the Achilles tendon overuse injuries. Force distribution between the three portions of the triceps surae muscle and position of the calcaneus might affect the extent of strain differences within the Achilles tendon. Purpose of this study was to determine the effect of changes in force distribution within the triceps muscle and changes in calcaneus position on intratendinous strain distribution of the Achilles tendon.

Methods

Five cadaveric Achilles tendons including complete triceps surae and calcaneus were dissected. Specimens were mounted in a loading simulator allowing independent force application for the three parts of triceps muscle and changes calcaneus eversion and inversion position. Strain was determined in different aspects of the Achilles tendon.

Findings

Changes of calcaneus position resulted in intratendinous strain differences up to 15%, changes in force distribution within the triceps muscle resulted in strain differences up to 2.5%. Calcaneal eversion was connected to a higher degree of strain in medial tendon portions, while inversion increased strain in lateral tendon portions.

Interpretation

Medio-lateral, proximo-distal and dorsal–ventral distribution of tendon strain is rather influenced by kinematics of the subtalar joint than by muscular imbalances within the triceps muscle. Clinical movement analyses should focus on motion pattern combining rearfoot eversion with high Achilles tendon load. The results indicate that twist of the Achilles tendon fascicles seems of paramount importance in balancing tendon strain. To get more insight into the Achilles tendon injuries pathogenesis future research should focus on methods monitoring heterogeneous distribution of strain in vivo.     

Surface electromyography activity of upper limb muscle during wheelchair propulsion: Influence of wheelchair configuration

Background

Biomechanical studies have linked handrim wheelchair propulsion with a prevalence of upper limb musculoskeletal disorders. The purpose of this study was to record upper limb muscle recruitment patterns using surface electromyography during wheelchair propulsion. Recordings were made for various wheelchair configurations to understand the effect of wheelchair configuration on muscle recruitment.

Methods

Ten paraplegic and ten able-bodied subjects propelled a test wheelchair on a roller ergometer system at a comfortable speed. Twelve wheelchair configurations were tested. Upper limb surface electromyography and kinematics were recorded for each configuration. Based on the hand position relative to the handrim, the propulsion cycle was divided into three phases to explain the activation patterns.

Findings

Compared to the able-bodied subjects, the paraplegic subjects presented higher activation. This is the case for all muscles in the early push phase, for the triceps brachii, pectoralis major and latissimus dorsi in the late push phase and for the trapezius, triceps brachii and latissimus dorsi during recovery. During early push, activation of nearly all muscles was affected by the axle position, where as seat height only affected biceps brachii and pectoralis major activation. During late push, the deltoid anterior was affected by axle position and the biceps brachii by seat height. During recovery, the trapezius was affected by axle position, the deltoid posterior by seat height and the biceps brachii by both.

Interpretation

Upper limb muscle recruitment differences highlight that future studies on wheelchair propulsion should only be done with wheelchair experienced paraplegic subjects. Furthermore, this study provides indications on how muscle recruitment is affected by wheelchair configuration.