A critical overview of the current myofascial pain literature - November 2018

Comparative Techniques of Acupuncture and Dry Needling Intersecting with Trigger Point Physiology and Diagnostics: A Cross-Discipline Narrative Review

Background

Pain management is a great burden on society; therefore, cost-effective and nonaddictive treatments for pain are urgently required. Needling of painful spots has been applied in acupuncture along with dry needling

Methods

A narrative review of the literature on TrP physiology, its associated diagnostics, and the techniques of DN and acupuncture was performed.

Results

Diagnostic imagery may benefit the study and treatment of TrPs using needling. Acupuncture and DN techniques are similar in their applications. However, the warm needling technique is established in acupuncture but not in dry needling. Additionally, translational difficulties have inhibited crossdiscipline learning.

Conclusions

Historical evidence suggests a need to examine the use of heat in needling further. Additional research should be conducted on TrP categories to determine if a relationship with the needling technique can be established. Furthermore, interdisciplinary communication would benefit both modalities.

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Key Words

• acupuncture
• dry needling
• myofascial trigger points
• trigger point physiology

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Affiliation(s)

Jordan Barber AOMA Graduate School of Integrative Medicine, Austin, TX, USA
Fabio Lodo So Wen School of Acupuncture, Milan, Italy
Andrew Nugent-Head Association for Traditional Studies, Ashville, NC, USA
Xia Zeng AOMA Graduate School of Integrative Medicine, Austin, TX, USA

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Acupuncture-like versus conventional transcutaneous electrical nerve stimulation in the management of active myofascial trigger points: A randomized controlled trial

PURPOSE

Myofascial pain syndrome (MPS) is one of the most common causes of chronic musculoskeletal pain. The transcutaneous electrical nerve stimulation (TENS) is a non-expensive, safe, feasible modality, used recently for the treatment of MPS with promising but limited results. The purpose of this study was to determine the efficacy of acupuncture-like TENS (AL-TENS) vs conventional TENS (C-TENS) in the treatment of active myofascial trigger points.

METHODS

This randomized controlled trial study was carried out with 60 consecutive patients with active trapezius trigger points referred to Physical Medicine and Rehabilitation Clinic. Participants randomly assigned to receive AL-TENS, C-TENS or sham TENS (S-TENS). The Visual Analogue Scale (VAS), Pressure Pain Thresholds (PPTs), and neck range of motion (ROM) were measured at baseline, after the first treatment sessions, after the final treatment session, and 3 months after the end of the last treatment session. Patients function was evaluated by Disabilities of the Arm, Shoulder, and Hand (DASH) at baseline, after the final treatment sessions, and 3 months after the end of intervention.

RESULTS

The interaction effect of time and group was significantly different when evaluating VAS (df = 4.65, F = 2.50, p = 0.038) and DASH (df = 2.63, F = 7.25, p < 0.001) in favor of active groups, as well as neck total lateral bending in favor of AL-TENS group compared other two groups (df = 4.16, F = 5.23, p = 0.001). Both VAS and DASH improved significantly at all follow-ups in AL-TENS and C-TENS groups. Of note, significant immediate improvement in all outcomes was observed only with AL-TENS.

CONCLUSIONS

According to the present study, both AL-TENS and C-TENS were superior to placebo in pain reduction and functional improvement. Although both TENS techniques have similar efficiency on pain reduction, functional and pain perception improvement, the AL-TENS was the superior approach when evaluating neck lateral bending ROM.

The Management of Foreign Body Sensation in the Throat after Stroke by Trigger Point Injection on Posterior Belly of Digastric Muscles

<p>Foreign body (FB) sensation in the throat is often a common symptom encountered in clinical practice. FB sensation in throat has numerous causes mainly caused by reflex diseases such as laryngopharyngeal reflux. Its treatment has been focused on organic problems or hysteria while musculoskeletal problem has been neglected. We hereby report a patient with dysphagia and complaint of FB sensation in the throat after nasogastric tube removal. It was relieved by trigger point injection on the posterior belly of digastric muscles.

P2X3 receptors contribute to transition from acute to chronic muscle pain

This study aimed to evaluate whether the development and/or maintenance of chronic-latent muscle hyperalgesia is modulated by P2X3 receptors. We also evaluate the expression of P2X3 receptors and PKCε of dorsal root ganglions during these processes. A mouse model of chronic-latent muscle hyperalgesia, induced by carrageenan and evidenced by PGE₂, was used. Mechanical muscle hyperalgesia was measured by Randall-Selitto analgesimeter. The involvement of P2X3 receptors was analyzed by using the selective P2X3 receptors antagonist A-317491 by intramuscular or intrathecal injections. Expression of P2X3 and PKCε in dorsal root ganglion (L4-S1) were evaluated by Western blotting. Intrathecal blockade of P2X3 receptors previously to carrageenan prevented the development and maintenance of acute and chronic-latent muscle hyperalgesia, while intramuscular blockade of P2X3 receptors previously to carrageenan only reduced the acute muscle hyperalgesia and had no effect on chronic-latent muscle hyperalgesia. Intrathecal, but not intramuscular, blockade of P2X3 receptors immediately before PGE₂, in animals previously sensitized by carrageenan, reversed the chronic-latent muscle hyperalgesia. There was an increase in total and phosphorylated PKCε 48 h after the beginning of acute muscle hyperalgesia, and in P2X3 receptors at the period of chronic muscle hyperalgesia. P2X3 receptors expressed on spinal cord dorsal horn contribute to transition from acute to chronic muscle pain. We also suggest an interaction of PKCε and P2X3 receptors in this process. Therefore, we point out P2X3 receptors of the spinal cord dorsal horn as a pharmacological target to prevent the development or reverse the chronic muscle pain conditions.

Viscero-visceral hyperalgesia in dysmenorrhoea plus previous urinary calculosis: Role of myofascial trigger points and their injection treatment in the referred area

BACKGROUND

Women with dysmenorrhoea plus symptomatic urinary calculosis experience enhanced pain and referred muscle hyperalgesia from both conditions than women with one condition only (viscero-visceral hyperalgesia). The study aimed at verifying if enhanced dysmenorrhoea persists after urinary stone elimination in comorbid women and if local anaesthetic inactivation of myofascial trigger points (TrPs) in the lumbar area (of urinary pain referral) also relieves dysmenorrhoea.

METHODS

Thirty-one women with dysmenorrhoea plus previous urinary calculosis (Dys+PrCal) and lumbar TrPs, and 33 women with dysmenorrhoea without calculosis (Dys) underwent a 1-year assessment of menstrual pain and muscle hyperalgesia in the uterus-referred area (electrical pain threshold measurement in rectus abdominis, compared with thresholds of 33 healthy controls). At the end of the year, 16 comorbid patients underwent inactivation of TrPs through anaesthetic injections, whereas the remaining 12 received no TrP treatment. Both groups were monitored for another year at the end of which thresholds were re-measured.

RESULTS

In year1, Dys+PrCal presented significantly more painful menstrual cycles and lower abdominal thresholds than Dys, thresholds of both groups being significantly lower than normal (p < .001). Anaesthetic treatment versus no treatment of the lumbar TrP significantly reduced the number of painful cycles during year2 and significantly increased the abdominal thresholds (p < .0001).

CONCLUSION

Viscero-visceral hyperalgesia between uterus and urinary tract may persist after stone elimination due to nociceptive inputs from TrPs in the referred urinary area, since TrPs treatment effectively reverses the enhanced menstrual symptoms. The procedure could represent an integral part of the management protocol in these conditions.

SIGNIFICANCE

A past pain process from an internal organ can continue enhancing pain expression from a painful disease in another neuromerically connected organ (viscero-visceral hyperalgesia) if secondary myofascial trigger points (TrPs) developed in the referred area at the time of the previous visceral disease. Inactivation of these TrPs reverts the enhancement. Assessment and treatment of TrPs in referred areas from past visceral pain conditions should be systematically carried out to better control pain from current diseases in other viscera.