Trigger points are hyperirritable taut bands of muscle that cause referred pain patterns locally or elsewhere in the body.

An active trigger point results in pain, while a latent trigger points elicits referred pain upon pressure or palpation. Either one can cause biomechanical changes that results in restricted range of motion and reduced muscle function.

Trigger points are sarcomere contractures - or tight bands of muscle. A trigger point starts out as a taut band of muscle, which then restricts blood flow and oxygen and reduces the pH of the surrounding area. The lower pH causes a downregulation of acetylcholinesterase which causes excessive acetylcholine, as well as a release of nociceptive biochemicals that create pain. The increase in pain chemicals in the body eventually results in changes to the nervous system like sensitization that can result in chronic pain and a lower pain threshold.

A 2005 Study looked at the biochemical makeup before, during, and after a local twitch response of a myofascial trigger point. The study found lower pH around active trigger points and increased levels of the following nociceptive chemicals:

• Calcitonin gene related peptide (CGRP)

• Inflammatory cytokines

• Substance P

• Bradykinin

• Serotonin and norepinephrine

• Prostaglandins

In particular – there were significantly elevated levels of Substance P and CGRP near active trigger points. After a local muscle twitch levels of these dropped significantly – which coincides with the general sensation of reduced pain after releasing a trigger point.

A follow-up study in 2008 confirmed that chemicals in the body associated with pain, inflammation, and increased pain signaling are higher near active trigger points.

A similar 2008 study found elevated levels of pain related chemicals in upper trapezius trigger points resulted in increased levels of those chemicals in other areas of the body that did not have trigger points (the gastrocnemius in the study), which suggests that myofascial trigger points may contributed to generalized pain and inflammation in other areas of the body.

The findings of these studies are consistent with the idea that muscle contracture leads to reduced blood flow and oxygen, which leads to the release of pain causing substances. Subsequently, dry needling can release myofascial trigger points with a local twitch response to restore blood flow and oxygen, and reduce pain.

How do trigger points form?

Generally, trigger points form from overuse or direct trauma to a muscle. There can also be other factors including stress and visceral problems that can also lead to the formation of trigger points.

Muscle overload that can result in trigger points can come from:

• Direct trauma to a muscle that causes a muscle to shorten

• Persistent low level muscle contractions like static posture or repetitive tasks

• Concentric muscle contractions that overload the muscle like from exercise and sports

How do you find trigger points?

Trigger points are found via patient history and a physical exam that includes palpation of affected areas and other possible areas that may refer pain. Using flat or pincer grip palpation allows the clinician to find active and latent myofascial trigger points. They will feel a taut band of muscle and be able to identify a contracture band along that band. The patient may feel their pain activated during the physical exam which confirms that there is an active or latent trigger point. Our acupuncturists are trained in trigger point dry needling and myofascial trigger point therapy will be able to find your trigger points based on the symptoms you are describing and by palpating for taut bands of muscle that elicit pain.

How do you release a trigger point?

Releasing a trigger point requires a mechanical intervention using a filiform acupuncture needle. The goal is to deactivate the trigger points by needling into the taut band and eliciting a local twitch response. The local twitch response is a spinal cord reflex and resembles a strong muscle ache or muscle spasm, and is an involuntary contraction of the muscle.

Brief History of Dry Needling

Originally, dry needling originated separately from traditional acupuncture and started with research on referral pain from various muscles by J.H. Kellgren in London in the 1930s. This research initially found that pain can occur in areas away from the actual site of pain (referred pain). This was found by injecting saline (an irritant) into muscles and observing the pain sensations that were felt as a result. Interestingly enough, the injections produced pain away from the injection site and in some cases the most pain was felt in other structures that were not the muscle.

After this realization, physicians began injecting trigger points with local anesthetics or other substances to relieve pain (wet needling). Physicians in the 1940s including Dr. Janet Travell further studied this type of pain and its clinical implications and eventually found that trigger points are the source of pain for numerous musculoskeletal pain issues. Research in 1949 showed that cardiac pain could have a somatic component that was caused by trigger points. By 1951, Dr. Travell and Dr. Seymour Rinzler had enough information about trigger points and referral patterns to provide illustrations for many causes of musculoskeletal pain.

Eventually, research by a Czech doctor in 1979 named Karel Lewit found that it was not necessary to inject any substances to relieve the pain caused by trigger points. Simply stimulating the muscle to release the trigger points was enough to alleviate the pain (dry needling). This was known as “the needle effect.”

In 1983, Dr. Travell and Dr. David Simons wrote the authoritative text on trigger points including their referral patterns, causes and treatment. According to Dr. Simons, “Dry Needling includes the use of sterile disposable acupuncture needles to improve circulation and blood flow to the affected muscle trigger point areas.”

Today, in its current form, dry needling uses filiform acupuncture needles instead of thicker and more painful hypodermic needles. Acupuncture needles are much thinner, generally don’t hurt when they are inserted, and have less side effects like bruising or bleeding that is often caused by hypodermic needles.

The history of traditional acupuncture and dry needling has some overlap since acupuncture has been used to treat pain for thousands of years whereas pain science that underlies myofascial trigger point theory is less than 200 years old.

How does dry needling relieve pain?

When muscles are tight they create pain, prohibit proper blood flow, and pull on the structures they attach to which may lead to a domino effect of pain that can spread throughout the body. Many common trigger points correspond with acupuncture points that have been around for many centuries. In the dry needling technique, we essential poke a muscle that is tight or shortened with the acupuncture needle which makes it contract involuntarily to restore function and lengthen the muscle closer to a more normal state. This allows more blood flow to return to the muscle and also relieves pulling at muscle attachment sites (bones and joints) that can cause pain and inflammation.

For more information about trigger points see our blog post Acupuncture for Trigger Points.

It is possible to experience soreness, muscle fatigue, and bruising at the needling site and that intensity of that often corresponds to the levels of muscle tightness prior to the treatment.

A 2019 review in the Journal of Pain Research highlights how dry needling can help relieve pain by releasing trigger points. To summarize:

• Trigger points have referred pain or referred sensation patterns that can be recreated upon stimulation of the trigger point area. For example, a trigger point in the trapezius muscle can create a referral pattern in the head that can create a headache.

• Releasing a trigger point usually involves obtaining a local twitch response at the muscle targeted. This is a brief and involuntary contraction of the muscle believed to be brought on by a spinal cord reflex. Some studies have shown that obtaining a local twitch response makes it more likely to relieve pain than just inserting the needle into a muscle without stimulation.

• Dry needling can result in post-needling soreness as a consequence of the neuromuscular stimulation that occurs during treatment. Most patients recover from the soreness within 48 to 72 hours and many patients describe it as similar to workout soreness.

• Studies have shown that dry needling is effective for managing musculoskeletal pain especially in the short to mid term (1 to 3 months). More studies need to be done to determine to longer term effects.

• Dry needling (acupuncture) also has an effect on the nervous system and parts of the brain which reduce the perception of pain by reducing peripheral nociception (the detection of painful stimuli).

Source: Fernández-de-Las-Peñas, C., & Nijs, J. (2019, June 18). Trigger point dry needling for the treatment of myofascial pain syndrome: current perspectives within a pain neuroscience paradigm. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/31354339

Common conditions associated with dry needling

• Headaches

• Facial & jaw pain

• Muscle tightness and soreness

• Repetitive strain injuries

• Tendonitis & bursitis

• Chronic postural pain

• Myofascial pain syndrome

• Lower back pain

• Upper back pain

• Neck pain

• Shoulder & arm pain

• Hip pain

• Knee pain

• Ankle & foot pain

• Wrist & hand pain

Specific conditions associated with dry needling

(From head to toe)

• TMJ pain & dysfunction

• Torticollis

• Shoulder and hip impingement syndromes

• Golfers and tennis Elbow

• Carpal tunnel syndrome

• Trigger finger

• Spinal disc problems

• Sciatica

• Piriformis syndrome

• Iliotibial band syndrome (IT band)

• Patello-femoral syndrome

• Shin splints

• Achilles tendonitis

• Plantar fasciitis