The Role of Psychological Factors in the Perception of Postneedling Soreness and the Influence of Postneedling Intervention

Soreness or sng: a common symptom with differential clinical impact from pain in degenerative lumbar spine diseases

INTRODUCTION

Soreness is a common complaint in patients who receive lumbar spine surgery (LSS) for degenerative lumbar spine diseases (DLSD). However, soreness is not assessed independently and its impacts on outcomes of LSS remains largely unknown. Sng(pronounced sә-ng, ) in Chinese language is the word with the closest meaning to soreness, and Chinese-speaking people naturally use sng to describe their non-pain 'soreness' symptom. This study was aimed to investigate the prevalence and impacts of soreness or sng on outcome of LSS by introducing Visual Analogue Scale (VAS) of sng on back and leg.

MATERIALS AND METHODS

This prospective cohort study recruited patients who receive LSS for DLSD. Participants completed the patient-reported outcome measures at 1 week before and 1 years after LSS. The patient-reported outcome measures included (1) VAS for back pain, leg pain, back sng and leg sng, (2) Oswestry Disability Index (ODI) and (3) RAND 36-item Short Form Health Survey. The minimal clinical important difference (MCID) of ODI and physical component health-related quality of life (HRQoL) was used.

RESULTS

A total of 258 consecutive patients were included and 50 dropped out at follow-up. Preoperatively, the prevalence of sng was comparable to pain both on back and leg; postoperatively, the prevalence of sng was higher than pain. Leg and back sng were associated with preoperative and postoperative mental HRQoL, respectively. The reduction of sng on back and leg were significantly less than pain postoperatively. Leg sng was the only symptom independently associated with attaining MCID.

CONCLUSION

Soreness or sng should be assessed independently from pain in patients receiving LSS for DLSD because soreness or sng had substantial clinical impacts on the outcome of LSS.

Effectiveness of spontaneous pain coping strategies for acute pain management: A laboratory study

The aim of the present study has been to analyze the relationship between the use of not previously trained, diverse acute pain coping strategies and levels of pain intensity and pain tolerance in a group of healthy participants. Previous research has analyzed the usefulness of the training of these strategies after several training sessions, but adequate patient training requires a great deal of time. Two hundred and forty healthy people participated in the study. Pain coping strategies was evaluated with a version of CSQ-S. Subsequently, the participants completed a cold pressor test and tolerance test. After that, subjects filled in the adaptation of the CSQ-S about the strategies which they had employed throughout the test. Correlation analyses showed a positive relationship between pain intensity and catastrophizing, distractor behaviors, hoping and ignoring the pain. Pain tolerance correlated with self-instructions, ignoring the pain, reinterpreting the pain, catastrophizing and faith and praying. Regression analyses showed that catastrophizing was found to be the strategy that most predicts the variance of pain intensity, and catastrophizing (negative) and ignoring the pain (positive) and praying (negative) were the most predictive ones for pain tolerance. This is the first laboratory study that identifies the more useful pain coping strategies which can be used by patients without previous training in an acute pain context. The results of this study could be useful in the development of protocols for nurses and other health professionals, especially for situations where potentially painful techniques are to be applied to patients.

Effectiveness of low-level gallium aluminium arsenide laser therapy for temporomandibular disorder with myofascial pain: A systemic review and meta-analysis

PURPOSE

Temporomandibular disorder (TMD) causes masticatory muscle pain and mouth opening limitations and affects patients' ability to eat, practice oral health and perform other activities of daily living. Although the benefits of low-energy lasers in treating TMD have been reported, the results vary greatly depending on the equipment used and the energy output. This study systematically evaluated the efficacy of a low-level gallium aluminium arsenide (GaAlAs) laser treatment for TMD with myofascial pain and maxillary pain.

METHODS

We searched the PubMed, EMBASE, Cochrane Library, Web of Science, and ClinicalTrials.gov databases for randomized controlled trials (RCTs) published since database inception to April 5, 2020, that compared low-level laser treatment to sham/placebo treatment or no intervention in patients suffering from TMD with myofascial pain. Three reviewers independently screened the literature, extracted data, and assessed the quality of the included studies according to the risk-of-bias tool recommended by the Cochrane Handbook V.5.1.0 (Cochrane Collaboration, London, UK). Then, a meta-analysis was performed using RevMan 5.3 and Stata 15.1 software.

RESULTS

The data from 8 randomized controlled trials including 181 patients were analyzed. The severity of myofascial TMD pain (measured on a visual analogue scale, VAS) at the end of treatment was significantly different between the control laser therapy and the low-level GaAlAs laser therapy (weighted mean difference [WMD] = -0.76, 95% confidence interval [CI] -1.51 to 0.01, P = .046); at 3 to 4 weeks after treatment, there was no significant difference (WMD = 1.24, 95% CI -0.04 to 2.51, P = .057). In addition, there was no significant improvement in maximum mouth opening (MMO) at the end of treatment (WMD = -0.03, 95% CI -4.13 to 4.06, P = .987) or at 3 to 4 weeks after treatment (WMD = 1.22, 95% CI -2.94 to 5.39, P = .565).

CONCLUSIONS

The results of this study suggest that there is insufficient evidence to indicate an efficacy of low-level GaAlAs laser therapy in improving TMD pain and maximal oral opening. These results suggest that clinicians should make appropriate recommendations to inform patient decision-making.

Efficacy of Exercise on Postneedling Soreness: A Randomized Controlled Trial

This study aimed to investigate the efficacy of concentric, eccentric, and isometric exercise protocols on the postneedling soreness (PNS) after the dry needling (DN) of latent myofascial trigger points (MTrP) in the medial gastrocnemius muscle. A randomized clinical trial was carried out. Volunteers, ≥18 years old, with a latent MTrP in the medial gastrocnemius muscle were included. Subjects with contraindications to DN, active MTrPs, and/or other treatments in MTrPs in the 3 months prior to recruitment were excluded. A total of 69 participants were randomly allocated to four groups, where post-DN intervention consisted of an eccentric, concentric, or isometric exercise, or no exercise, and they were assessed for PNS intensity (visual analog scale (pVAS)), pressure pain threshold (PPT, analog algometer), pain intensity (nVAS), and local twitch responses (LTRs) during DN, as well as demographics and anthropometrics. The mixed-model analyses of variance showed significant interaction between time and pVAS, and between time and PPT (p < 0.001). While the multivariate test confirmed that PNS and PPT improved over time within each group, specifically between 6–12 h post-intervention, the post hoc analyses did not show significant differences between groups. The mixed-model analyses of covariance showed a significant nVAS effect (p < 0.01) on PNS decrease, and some effect of the LTRs (p < 0.01) and sex (p = 0.08) on PPT changes. All groups improved PNS and PPT, but none of them showed a greater improvement above the others. The most dramatic decrease was observed between 6–12 h post-exercise, although concentric and eccentric exercise had an effect immediately after the intervention. Between all potential modifiers, pain during DN significantly influenced PNS progression, while LTRs and sex seemed to determine PPT course over time.

Pressing Intervention Promotes the Skeletal Muscle Repair of Traumatic Myofascial Trigger Points in Rats

Objective

To observe the effect of pressing intervention on the skeletal muscle repair of myofascial trigger points (MTrPs) in rats and explore the mechanism of pressing intervention on the deactivation of trigger points.

Methods

Thirty SPF rats were randomly divided into blank group, model group and press group, with 10 rats in each group. The MTrPs models were established by blunt striking plus eccentric exercise, and then evaluated. The press group was given a pressing intervention with a self-made device for 14 days, and the rats in the other two groups were fed normally. Soft tissue tension (STT) D_0.2 and pressure pain threshold (PPT) were measured before and after intervention. The skeletal muscle tissue at MTrPs was extracted and assessed by hematoxylin–eosin (HE) and Masson staining. The expression of collagen I, collagen III, α- smooth muscle actin (α-SMA), myosin heavy chain (MHC) and fibronectin (FN) were detected by Western Blotting. Enzyme linked immunosorbent assay (ELISA) was used to evaluate the expression of substance P (SP), 5-hydroxytryptamine (5-HT), cyclooxygenase 2 (COX-2) and prostaglandin E2 (PGE2).

Results

(1) Compared with the blank group, the PPT and D_0.2 reduced (P < 0.05) in the model group; while compared with the model group, the PPT and D_0.2 increased (P < 0.05) in the press group. (2) Compared with the blank group, the model group showed obvious spontaneous potentials with higher amplitude and frequency, which were also much higher than those of the press group (P < 0.05). (3) The HE and Masson staining results showed evident fibrosis in the muscle tissue of the model group, with a larger area of collagen fibers relative to that of the press group (P < 0.05). (4) The amount of collagen I, collagen III, FN, α- SMA, SP, 5-HT, COX-2 and PGE2 increased and the content of MHC decreased (P < 0.05) in the model group, as compared to the blank group; while all the substances (P < 0.05), instead of MHC which increased (P < 0.05), in the press group were decreased as compared to the model group.

Conclusion

Pressing intervention on the MTrPs in rats can alleviate chronic inflammation, inhibit fibrosis, promote skeletal muscle repair and relieve pain.

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 Influence of Verbal Suggestion on Post-Needling Soreness and Pain Processing after Dry Needling Treatment: An Experimental Study

BACKGROUND

It remains unclear as to whether verbal suggestions and expectancies can influence the perception of post-needling soreness. The aim of this study was to analyze the effects of verbal suggestions on post-needling soreness after dry needling of the trapezius muscle.

METHODS

This study is a randomized controlled trial including healthy subjects randomly assigned to one of three groups receiving different verbal suggestions about the effects of dry needling and the occurrence of post needling soreness (positive, negative, or neutral). Then, dry needling on a latent trigger point of the upper trapezius muscle was performed and the following outcomes were measured immediately after, 24, 48, and 72 h, and one week after the intervention: post-needling soreness intensity, pressure pain threshold (PPT), temporal summation (TS) and conditioned pain modulation (CPM).

RESULTS

Seventy-three consecutive participants were screened and 42 participants (12 men and 30 women, aged: 24 ± 8 years old) were eligible and finished the study protocol. The results showed that verbal suggestion did not influence the perception of post-needling soreness, since there were no differences between groups (p < 0.05) on the intensity of post-needling soreness or tenderness over a one-week follow-up. Moreover, verbal suggestion did not associate with changes in sensorimotor variables of TS and CPM.

CONCLUSIONS

The induction of different types of expectations through verbal suggestion does not influence the perception of acute pain perceived during the performance of a deep dry needling technique and post-needling pain or soreness after deep dry needling on a latent upper trapezius myofascial trigger point (MTrP).

Effectiveness of Deep Dry Needling vs Ischemic Compression in the Latent Myofascial Trigger Points of the Shortened Triceps Surae from Triathletes on Ankle Dorsiflexion, Dynamic, and Static Plantar Pressure Distribution: A Clinical Trial

OBJECTIVE

To determine the immediate efficacy of a single session of deep dry needling (DDN) vs ischemic compression (ICT) in a latent myofascial trigger point (MTrP) of the shortened triceps surae from triathletes for ankle dorsiflexion and redistribution of plantar pressures and stability.

DESIGN

A randomized simple blind clinical trial (NCT03273985).

SETTING

An outpatient clinic.

SUBJECTS

Thirty-four triathletes with a latent MTrP in the shortened gastrocnemius.

METHODS

Triathletes were randomized to receive a single session of DDN (N = 17) or ICT (N = 17) in a latent MTrP of the shortened triceps surae. The primary outcome was ankle dorsiflexion range of motion (ROM) by a universal goniometer. Secondary objectives were distribution of dynamic and static plantar pressures by T-Plate platform pressure, with measurements both before and after five, 10, 15, 20, and 25 minutes of treatment.

RESULTS

There were no statistically significant differences (P > 0.05) for ankle dorsiflexion ROM or dynamic and static plantar pressures between the experimental group treated with DDN and the control group treated with ICT before and after treatment.

CONCLUSIONS

DDN vs ICT carried out in latent MTrPs of the shortened gastrocnemius of triathletes did not present differences in terms of dorsiflexion ROM of the tibiofibular-talar joint or in static and dynamic plantar pressure changes before and immediately after treatment.

Effects of Acupuncture on Delayed-Onset Muscle Soreness: A Systematic Review and Meta-Analysis

Objectives

Evidence for the effects of acupuncture on delayed-onset muscle soreness (DOMS) is inconsistent. The aim of this study was to explore the effects of acupuncture on DOMS.

Methods

Studies investigating the effect of acupuncture on DOMS in humans that were published before March 2020 were obtained from eight electronic databases. The affected muscles, groups, acupuncture points, treatment sessions, assessments, assessment times, and outcomes of the included articles were reviewed. The data were extracted and analyzed via a meta-analysis.

Results

A total of 15 articles were included, and relief of DOMS-related pain was the primary outcome. The statistical meta-analysis showed that there were no significant differences between acupuncture and sham/control groups, except for acupuncture for DOMS on day 1 (total SMD = −0.62; 95% CI = −1.12∼0.11, P < 0.05) by comparing with control groups.

Conclusion

Acupuncture for DOMS exhibited very-small-to-small and small-to-moderate effects on pain relief for the sham and no acupuncture conditions, respectively. Evidence indicating the effects of acupuncture on DOMS was little because the outcome data during the follow-up were insufficient to perform an effective meta-analysis.

Impact of physical therapists' instructions on function and the perception of post-dry needling soreness in mechanical cervical pain; a randomized clinical trial

BACKGROUND

To investigate the impact of physical therapists' instructions on the perception of post dry needling (DN) soreness and function in patients with mechanical neck pain.

METHODS

Seventy-five patients with neck pain were randomly assigned to three groups: "positive" group (n = 25) received positive verbal input; "negative" group (n = 25) received negative verbal input, and control group (n = 25) did not receive any input about post-needling soreness. All three groups received DN of a trigger point in the upper trapezius muscle. The subjective pain experience, pressure pain threshold (PPT), and neck disability Index (NDI) were assessed before and after DN.

RESULTS

Patients in all groups showed improvement in pain, PPT and NDI. There were no significant differences in pain (P = 0.41) and PPT (P = 0.68) in the positive and negative groups compared with the control group. Significant difference in function was seen with the NDI after DN of patients in the positive and negative groups compared with the control group (P = 0.011, standard error: 1.08-1.5).

CONCLUSION

Considering that the power of our study may be too low to draw more definitive conclusions, DN appears to be an effective technique to improve pain and mechanical hyperalgesia. The experience of post-needling soreness does not appear to influence the outcome of DN on pain, PPT, and NDI. Post-needling soreness does not seem to be a limiting factor in achieving acceptable outcomes, especially when clinicians offer DN within a therapeutic emphasizing a positive patient response. This study questions whether any treatments need to be offered to patients receiving DN.

Effects of pain neuroscience education and dry needling for the management of patients with chronic myofascial neck pain: a randomized clinical trial

OBJECTIVES

The aim of this study was to observe the medium-term effects on pain, disability, and psychological factors of a combination of myofascial trigger point (MTrP) dry needling (DN) with pain neuroscience education (PNE) versus DN alone versus control care as usual (CUC) in patients with chronic neck pain.

METHODS

A total of 60 patients were randomly selected in a Spanish National Health Service Public Hospital and divided into three groups: 6 sessions of DN with 3 sessions of PNE (TrPDN + PNE group, n = 21), 6 sessions of DN alone (TrPDN group, n = 20), or 10 sessions of usual care (CUC group, n = 19). The primary outcome was neck pain intensity, while neck disability, medication intake, and psychological factors were secondary outcomes. These variables were measured at baseline, post-treatment, and at 1 month and 3 months after treatment.

RESULTS

TrPDN + PNE and DN alone were associated with greater reductions in pain intensity and disability compared to CUC (p < 0.01). TrPDN + PNE resulted in greater improvements in kinesiophobia, pain anxiety, and pain-related beliefs than DN alone and CUC (p < 0.01). No differences between groups were observed in medication intake, quality of life, catastrophizing, depression, or fear of pain (p > 0.05).

DISCUSSION

Provision of PNE and DN in the management of chronic neck pain in a Spanish National Health Service Public Hospital was associated with greater improvements in psychological factors than DN therapy only.

CONCLUSION

DN alone was more effective at reducing chronic non-specific neck pain and disability than CUC at 3-month follow-up. However, the inclusion of PNE combined with DN resulted in greater improvements in kinesiophobia, pain anxiety, and pain-related beliefs.

TRIAL REGISTRATION NUMBER

NCT03095365 (ClinicalTrials.gov).

Central Sensitization and Catastrophism Symptoms Are Associated with Chronic Myofascial Pain in the Gastrocnemius of Athletes

Objective

To compare central sensitization symptoms, presence of central sensitivity syndrome (CSS), catastrophism, rumination, magnification, and helplessness symptoms between athletes with gastrocnemius myofascial pain and healthy athletes. Furthermore, to predict central sensitization symptoms based on sociodemographic and descriptive data, catastrophism features, and presence of gastrocnemius myofascial pain in athletes.

Design

Case–control study.

Setting

Outpatient clinic.

Subjects

Fifty matched paired athletes were recruited and divided into patients with chronic (more than three months) gastrocnemius myofascial pain (N = 25) and healthy subjects (N = 25).

Methods

Central sensitization symptoms and CSS presence (≥40 points) were determined by the Central Sensitization Questionnaire (CSQ). Catastrophism symptoms and rumination, magnification, and helplessness domains were measured by the Pain Catastrophizing Scale (PCS). Statistical significance was set at P &lt; 0.01 for a 99% confidence interval.

Results

Statistically significant differences (P ≤ 0.001) with a large effect size (d = 1.05–1.19) were shown for higher CSQ scores and PCS total and domain scores in athletes with gastrocnemius myofascial pain vs healthy athletes. Nevertheless, CSS presence (CSQ ≥ 40 points) did not show statistically significant differences (P = 0.050) between groups. A linear regression model (R2 = 0.560, P &lt; 0.01) predicted higher CSQ scores based on PCS total score (R2 = 0.390), female sex (R2 = 0.095), and myofascial pain presence (R2 = 0.075).

Conclusions

Greater symptoms of central sensitization, catastrophism, rumination, magnification, and helplessness were shown in athletes with gastrocnemius myofascial pain compared with healthy athletes. Nevertheless, there was not a statistically significant presence of CSS comparing both groups. Greater central sensitization symptoms were predicted by catastrophism symptoms, female sex, and presence of gastrocnemius myofascial pain in athletes.

A critical overview of the current myofascial pain literature - February 2019

This edition of the overview of current myofascial pain literature features several interesting and important publications. From Australia, Braithwaite and colleagues completed an outstanding systematic review of blinding procedures used in dry needling (DN) studies. Other papers tackled the interrater reliability of the identification of trigger points (TrP), the presence of muscle hardness related to latent TrPs, pelvic floor examination techniques, and the links between TrPs, headaches and shoulder pain. Israeli researchers developed a theoretical model challenging the contributions of the Cinderella Hypothesis to the development of TrPs. As in almost all issues, we included many DN, injection and acupuncture studies, which continue to be the focus of researchers all over the world.

Postneedling Soreness and Tenderness After Different Dosages of Dry Needling of an Active Myofascial Trigger Point in Patients With Neck Pain: A Randomized Controlled Trial

BACKGROUND

Previous studies in asymptomatic subjects have demonstrated that myofascial trigger point (MTrP) dry needling frequently is associated with postneedling soreness. However, to the authors' knowledge, there is not any study that performs a detailed description of postneedling soreness characteristics in patients with myofascial pain. This information could help clinicians to make evidence-informed decisions considering the benefits and negative effects of different dry needling dosages.

OBJECTIVE

To (1) compare the prevalence, intensity, and duration of postneedling soreness and tenderness after different dosages of deep dry needling (DDN) and (2) analyze the influence on postneedling soreness of psychological factors and other factors involved in the DDN process DESIGN: 1-week follow-up, double-blind randomized controlled trial.

SETTING

University community.

PARTICIPANTS

Patients (n = 120: 34 male; 86 female) aged 18-53 years (median ± interquartile range, 21.0 ± 7.0 years) with active MTrPs in the upper trapezius.

INTERVENTION

All patients received DDN in an active MTrP. They were randomly divided into 4 groups: no local twitch responses (LTRs) elicited (control group), 4 LTRs elicited, 6 LTRs elicited, and DDN until no more LTRs were elicited.

MAIN OUTCOME MEASURES

Postneedling soreness and pressure pain threshold were assessed before treatment, during DDN procedure, and every 24 hours during 1 week.

RESULTS

Postneedling soreness showed a significant effect for time (F_2,006 = 173.603; P < .001, η_p² = 0.659) and a significant interaction between group and time (F_6,017 = 3.763; P = .001; η_p² = 0.111). Pressure pain threshold showed a significant effect for time (F_2,377 = 16.833; P < .001; η_p² = 0.127) and a significant interaction between group and time (F_7,130 = 2.100; P = .04; η_p² = 0.052). Psychological factors did not show relevant correlations with the intensity of postneedling soreness.

CONCLUSIONS

Postneedling soreness is present in most of subjects after DDN of active MTrPs. The groups in which DDN was performed eliciting LTRs exhibited greater post-needling soreness. The number of needle insertions was associated with postneedling soreness but psychological factors did not seem to play a relevant role on its perception.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02190890 LEVEL OF EVIDENCE: I.

Efficacy of quadriceps vastus medialis dry needling in a rehabilitation protocol after surgical reconstruction of complete anterior cruciate ligament rupture

BACKGROUND

Several new rehabilitation modalities have been proposed after anterior cruciate ligament (ACL) reconstruction. Among these, trigger point dry needling (TrP-DN) might be useful in the treatment of myofascial pain syndrome associated with ACL reconstruction to reduce pain intensity, increase knee flexion range and modify the mechanical properties of the quadriceps muscle during late-stage rehabilitation. To date, this is the first randomized clinical trial to support the use of TrP-DN in the early rehabilitation process after ACL reconstruction. The aim of this study was to determine the pain intensity, range of motion (ROM), stability, and functionality improvements by adding quadriceps vastus medialis TrP-DN to the rehabilitation protocol (Rh) provided to subacute ACL reconstructed patients.

METHODS

This randomized, single-blinded, clinical trial (NCT02699411) included 44 subacute patients with surgical reconstruction of complete ACL rupture. The patients were randomized into 2 intervention groups: Rh (n = 22) or Rh + TrP-DN (n = 22). Pain intensity, ROM, stability, and functionality were measured at baseline (A0) and immediately (A1), 24 hours (A2), 1 week (A3), and 5 weeks (A4) after the first treatment.

RESULTS

Comparing statistically significant differences (P ≤ .001; Eta = 0.198-0.360) between both groups, pain intensity (at A1), ROM (at A1, A2, and A3), and functionality (at A2, A3, and A4) were increased. Nevertheless, the rest of measurements did not show significant differences (P > .05).

CONCLUSION

Quadriceps vastus medialis TrP-DN in conjunction with a rehabilitation protocol in subacute patients with surgical reconstruction of complete ACL rupture increases ROM (short-term) and functionality (short- to mid-term). Although there was an increase in pain intensity with the addition of TrP-DN, this was not detected beyond immediately after the first treatment. Furthermore, stability does not seem to be modified after TrP-DN.