Research Review By Dr. Shawn Thistle©

Date Posted:

March 2010

Review Title:

Remote Needling for Trapezius Trigger Points

Publication Information:

  1. Tsai C-T, Hsieh L-F, Kuan T-S et al. Remote effects of dry needling on the irritability of the myofascial trigger point in the upper trapezius muscle. Am J Phys Med Rehabil 2010; 89:133-140.
  2. 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. Arch Phys Med Rehabil 2009; 90:905-912.

Background Information:

A Trigger Point (TrP) is defined as a localized, hyperirritable, taut band of skeletal muscle that, upon manual palpation, causes a typical pain referral pattern and/or a local twitch response (LTR – a sudden forceful contraction of a group of muscle fibers in a taut band). TrPs are further categorized into active - which create spontaneous pain, and latent - which become painful only on palpation or compression. An individual TrP can also contain multiple painful loci that will respond to mechanical pressure (normally applied via the end of an acupuncture needle).

As you know, TrPs are extremely common (particularly in the upper trapezius) and can generally respond well to a variety of interventions. For years, acupuncture has been used to effectively treat TrPs*. Although the mechanism of therapeutic effectiveness remains unclear, it has been suggested that acupuncture can modulate pain signals through hyperstimulation analgesia mediated by spinal cord reflexes (1), and have mechanical effects on connective tissue orientation.

Further, acupuncture is commonly applied in remote locations to the area of primary complaint. The physiological mechanism for this remote effect is also uncertain. According to traditional acupuncture, points exist on meridians throughout the body that are neurologically connected. Practically, these meridians often follow the referral patterns of certain musculoskeletal structures, and when distal needles are inserted, proximal TrPs can be relaxed.

The two studies reviewed here attempt to add to this body of knowledge by testing this theory.

*NOTE: acupuncture will be used synonymously with “dry needling”, even though they typically differ somewhat. To date, I am unaware of any studies showing that they have significantly different clinical outcomes. In general, dry needling involves the use of a slightly bigger needle manipulated vigorously to obtain LTRs during treatment – this is often quite painful. Acupuncture on the other hand involves more slender needles that may be stimulated manually by pistoning or rotating (or both), or with various frequencies of electricity (normally referred to as electroacupuncture).

Pertinent Results:

Study #1: Tsai et al. (2010):

This study aimed to investigate the effect of remote dry needling on the irritability of a myofascial trigger point in the upper trapezius. 35 patients (average age ~44, 14 males) with unilateral shoulder pain secondary to TrPs in the upper trapezius fibers who had never been needled were randomized to one of two groups:
  1. Control Group (n=18): received sham needling
  2. Experimental Group (n=17): received dry needling to a myofascial TrP in the extensor carpi radialis longus (ECRL) muscle (see picture below)
Patients were excluded if they had: any contraindications to needling, conditions that may affect the measurement of pain threshold, communication issues, previous surgery to upper back or neck, history of neurological deficit, or any other serious medical problem. In each patient, TrPs were identified and marked in the active TrP in the upper trapezius and the latent TrP in the ipsilateral ECRL (3-4cm distal to the lateral epichondyle). Before and after needling, pain intensity in the upper trapezius TrP was verbally reported on a 10 point scale. Pressure pain threshold was also assessed using a handheld algometer – with the patient seated and instructed to say “pain” when the compression (applied at 1Kg/sec) became painful. The average of three values was used for the PPT recordings. ROM of the cervical spine lateral bending was also measured pre- and post-needling with a wall scale and head mounted goniometer.

Dry Needling Technique:
  • once the TrPs were identified, firm pressure was applied with the non-dominant index or middle finger of the clinician to direct needle tip placement
  • a 5 mL syringe connected to a 25-hypodermic needle (0.5mm in diameter) which was 1.5 inches in length was held in the dominant hand – then inserted into the skin above the TrP
  • after penetration, the needle was rapidly and repeatedly inserted into the TrP to elicit LTRs, until no further LTRs could be elicited (usually 1-2 minutes) – the authors note that LTRs were elicited from all TrPs needled in this study
  • sham needling consisted of a needle penetrating only the subcutaneous layer of the skin over the TrP region in the ECRL – the needle was then moved in a similar manner to the experimental group but without further penetration
Pertinent Results:
  • there were no significant differences between the study groups aside from a higher average age in the experimental (~46 yoa) versus the control group (~41 yoa)
  • immediately after dry needling, the experimental group’s average pain intensity was decreased, while cervical ROM increased
  • every patient in the needling group had an increased PPT post-treatment, indicating reduced irritability (P < 0.05)
  • significantly larger changes in all three parameters were noted in the experimental group than in the control group
  • subjective pain intensity was reduced by a significant margin in the experimental group (P < 0.05) – as all but 2 subjects reduced their pain scored by at least 50% (5/10 points); significant pain reduction was not noted in the control group (P > 0.05)
  • 2 subjects in the experimental, and 6 in the control group reported no change in pain after the intervention
  • only one patient in the experimental group did NOT show an improved cervical ROM after treatment (versus 5 in the control group), and the change was only significant in the experimental group (P < 0.05) – the average increase in ROM was roughly 12 degrees
Needle Inserted Into Proximal ECRL
Study #2: Chou et al. (2009):

This study involved 20 patients (average age ~35, 8 males) with active TrPs in the trapezius muscle who had no prior experience with acupuncture. Patients had to have “intolerable chronic pain in one shoulder with active TrPs in the upper trapezius” that had not responded to other therapies such as oral medication or physical therapy (unspecified). Subjects were randomized into one of two groups:
  1. Control Group (n=10): received sham acupuncture
  2. Experimental Group (n=10): received acupuncture to points Wai-guan (also called Triple-energizer-5 [TE-5], in the extensor indicis muscle on the dorsal forearm, between the ulna and radius, 3cm proximal to the wrist crease) and Qu-chi (also called Large-intestine-11 [LI-11], in the ECRL on the lateral side of the cubital crease with the elbow in full flexion)
Exclusion criteria were similar to the study above. Before and after treatment, each subject reported subjective pain levels (via numeric pain rating scales from 0-10 as above), as well as having recordings made of end plate noise (EPN)/EMG activity of the trapezius TrP loci via needle electrode.

Needling Procedure:
  • acupuncture points were identified using traditional methods, as well as palpation to confirm the presence of “Ah-Shi” or tender TrPs
  • patients were in a prone position, which allowed simultaneous needling and recording of EMG/EPN in the trapezius
  • disposable, #30 acupuncture needles (25mm length) were used, first inserted into the subcutaneous layer, then moved in and out of the forearm points/TrPs at a speed of ~ 2cm/second while simultaneously being rotated (so, basically similar to the technique used in study #1) – this was performed for ~15 seconds, then the needle was left inserted for at least 3 minutes
  • the needle in TE-5 was inserted and stimulated first, and left in for the whole treatment as LI-11 was being treated – both needles were then stimulated simultaneously and then left in for a few more minutes
  • ”De-Qi”, or soreness ± LTR, was the goal of the needling treatment, which was subjectively reported by each subject or observed
  • the control group had needles inserted into the skin only at the same points, which were held in place by tape and a rubber tube that held the needle upright (this technique has been used in other acupuncture studies)
Pertinent Results:
  • pain intensity in the trapezius TrP was significantly reduced after remote needling (from ~7.4 to ~3.3 average pain scale reports – representing a 55% change), but not after sham acupuncture
  • the average EPN (an indication of muscle irritability) was significantly reduced after needling (P < 0.01) but not after sham acupuncture (P > 0.05)
  • the changes observed in pain intensity were significantly correlated to the changes in EPN

Clinical Application & Conclusions:

Both of these studies provide interesting evidence supporting the use of peripheral or remote needling in the treatment of TrPs in the upper trapezius, one of the most common places this painful entity occurs. It appears that needling in the forearm can alter EMG activity, pressure pain threshold/irritability and subjectively reported pain levels in patients with pain originating (at least partially) from trapezius TrPs.

In a broader sense, these studies support the long held theory that TrPs share spinal connections and can influence each other. This supports previous literature, and in the case of Tsai et al., improves on it by adding a sham procedure to the experimental investigation.

The authors of both studies suggest that the hyperstimulation analgesia noted in their studies is likely due to diffuse noxious inhibitory control - referring to the application of a noxious stimulus, that through segmental inhibition, reduces pain in related structures.

The tip of an acupuncture needle can apply a high level of direct pressure (pressure = force/area) – such a stimulus creates strong afferent signals that transmit to the spinal cord. Previous literature has suggested that the greater the pain intensity at the site treated, the greater the DNIC effect (2) – these studies were not designed to assess this phenomenon but both did ensure that patients reported feeling “De Qui” or discomfort during treatment.

These two studies are not without limitations – both did not have control groups and had small-ish sample sizes for example. Further, neither study evaluated long-term effectiveness, which would obviously provide additional information for those of us in practice.

That being said, the findings here point us in an interesting direction, and provide a treatment option that is easy and time-efficient to apply.

Additional References:

  1. Hong CZ. Myofascial trigger points: Pathophysiology and correlation with acupuncture points. Acup Med 2000; 18:41-47.
  2. Villanueva L & Le Bars D. The activation of bulbospinal controls by peripheral nociceptive inputs: Diffuse noxious inhibitory controls. Biol Res 1995; 28:113.125.