TRIGGER POINTS


They are the most common cause of chronic musculoskeletal pain in the Myofascial Pain Syndrome_ MPS, a regional pain syndrome, originated from regional Trigger Points or TPs.

TPs are the most common cause of chronic musculoskeletal pain. About 75% of pain is caused by TPs.

TRAVELL and SIMONS define a Trigger Point_ TP as a tender nodule, a muscle knot in a palpable taut band of skeletal muscle.
It is an irritable spot either spontaneously (active) or on digital compression (latent) able to generate either local or referred pain to other musculature, motor dysfunction and even autonomic phenomenon such as sweating, swelling, and "goose bumps."
These TPs may become activated by a variety of factors such as, poor posture, overuse, or muscle imbalance.
TPs exhibit a local twitch response (muscle fasciculation) or jump sign (flexion response) in response to digital pressure or Dry & Wet Needling.

TPs can be Active or Latent, depending on their varied clinical characteristics (Han and Harrison, 1997; Travell and Simons, 1999); however, either of these may cause musculoskeletal pain (Travell and Simons, 1999; Wilks, 2002; Hou, 2002): Active and Latent TPs can cause significant motor dysfunction but more commonly occurring with Latent TPs than Active TPs (Travell and Simons, 1999).

Active Trigger Point ATP

It is a hypersensitive point; it may display continuous pain in the zone of reference with or without palpation.
Palpation of the muscle injured, reveals a

  • Muscular stiffness and weakness: Muscle is with increased muscular tension, reduced muscular stretch, restricted range of motion.
  • Taut band and local twitch response located in the muscle.
  • Spontaneous pain referral.  Localized and referred pain appeared on manual compression simulating by all aspects the current pain. [Travell and Simons (1999); Chaitow and DeLany (2002) Wilks (2002)].

Latent Trigger Point_ LTP

Is a TP more commonly occurring, hypersensitive with active nociceptors but not enough to generate spontaneous pain and it is not associated with spontaneous pain referral (Travell and Simons, 1999; Alvarez & Rockwell, 2002). We find also a taut band.
However, it exhibits all the muscular characteristics of an ATP: Stiffness and restricted range of motion due to increased muscle tension and shortening, muscular weakness.  
Manual compression causes localized pain, local twitch response with a ‘jump sign’ (muscular flexion}.

ATP and LTP can be subdivided into Primary TP and Satellite TP.

  • Primary TP
    A Primary TP is defined as a TP that has been activated directly by acute or chronic overload or repetitive overuse of the muscle in which it occurs and was not activated as a result of TP activity in another muscle (Travell and Simons, 1999)

A Primary TP contains nociceptors activity and is mainly responsible for the development of the Myofascial pain.
 Further aggravating factors can lead to the creation of an active trigger point, which may recover spontaneously or persist without further development.

  • Satellite TP
    A Satellite TP is induced mechanically by an Active Primary TP (Travell and Simons, 1999). A Satellite TP forms within the pain referral zone of another muscle containing a Primary TP. Satellite TP result from the stress and muscle spasm caused by neighboring TPs. As such an Active TP in one muscle can induce an Active Satellite TP in another muscle and vice versa, inactivation of the key TP will therefore lead to inactivation of its Satellite TP without actually treating the Satellite TP (Travell and Simons, 1999).

According to Davies and Davies ‘long term chronic pain is often a compound effect from a chain of Satellite TPs, cascading from muscle to muscle.

  • Secondary TP
    A Secondary TP develops in synergistic muscles of the affected muscle. An imbalance of tension in the primary muscle, due to shortening muscle fibers and, compensatory overload of the synergistic muscles, causes Secondary TPs to develop.
  • Of the trigger points actually found within the zone of pain, most of those are not very common trigger points, or they formed because they were satellite trigger points formed due to primary trigger points elsewhere.


Contributing factors

Among the various direct causes or contributing factors, generating TPs in Patients, mention may be made, with many authors of:  

  • Occupational or athletic activities with postural deficiencies, muscle imbalances, overuse injuries, intervertebral discs diseases, trauma…
  • Psychosocial and emotional factors, fatigue…
  • Inflammatory diseases, fever, arthritis, viral infections,
  • Internal disease, scar formation after surgical incision etc…

Perpetuating or aggravating factors

 Further aggravating factors may lead to the creation of further TPs 

Chronic psychological problems,
Chronic infections,
Chronic muscle tension due to poor posture…


The existence and understanding of the genesis of the TPs, was the subject of many debates involving EMG, elastography, Magnetic Resonance, ultrasound etc. to both confirm their existence and obtain a more extensive knowledge of the pathophysiology of these TPs, commonly overlooked cause of chronic musculoskeletal pain and dysfunction.The etiology and genesis of TPs have yet to be satisfactorily explained.

It is generally thought that abnormal muscle strain, in combination with emotional stress, in genetically predisposed individuals, can cause a LTP to develop in a taut muscle band and subsequent nerve sensitization. 
Taut muscle bands commonly occur in pain-free individuals.

Several diverse yet complementary models have been proposed to explain the development of TPs at the cellular level, but it is still not known what the role of each is in the pathogenesis of chronic musculoskeletal pain. Nonetheless, it is clear that the pathogenesis of TPs is a complex process that involves both the central and peripheral nervous systems.

Recent basic studies have confirmed that,  at the site of an active TP, there are elevated levels of inflammatory mediators, known to be associated with persistent pain states and myofascial tenderness and that this local milieu changes with the occurrence of local twitch response.

Appropriate treatment

Appropriate treatment to the locally musculoskeletal pain and dysfunction could be performed by needling therapies applied into the TP, a locally painful area, to produce a “twitch” response and deactivate the TP.

Needling therapies can be divided in two groups with or without liquid drug injected:

  • Two versions of Acupuncture: Acupuncture & Mesopuncture.
  • Two versions of DN: Wet & Dry needling, in association with other treatments, optionally. 





In the book published in 1981, Myofascial Pain and Dysfunction, the Trigger Point Manual, describing the fundamentals of Travell and Simons work, can be found, in the chapter      'Methods to deactivate a trigger point’, the original description of the WN and DN:


“Dry, as opposed to Wet needling, is defined as needling the soft tissue without injection of any liquid substance to treat human pathology”.
We also find in this book, among other methods to deactivate a TP, comments on hypodermic needle injection of a variety of chemicals.


“In comparative studies, DN was found to be as effective as injecting an anesthetic solution such as procaine or lidocaine in terms of immediate inactivation of the TP. All substances injected had a positive effect, including simple saline solution”.
It should be noted the similarity with Mesopuncture. In both cases, it is the local injection of small doses of a liquid drug with, on one hand, known pharmacological and on the other hand mechanical properties, due to the volume injected.


The Therapist utilizes a hypodermic needle inserted into the skin, to allow the liquid drug to cross the skin and reach the TP to deactivate it with the goal of a long-term pain relief.  


The needle
The insertion pain of a hollow hypodermic needle in the Trigger Point, already painful, is accentuated by the various manipulations performed in the TP to disable it.

This pain is optimized by using the hollow needle BMN whose diameter is identical to the diameter of acupuncture needles and by the properties of the liquid drug injected.


The liquid drugs
Currently, it is easier using DN than Wet Needling (WN) but WN optimizes the effectiveness of Trigger-Points treatment:


Indeed, using a liquid drug depends on one hand of the medical expertise of the Therapist, entitled to use liquid drugs injected and knowing, perfectly, the complete pharmacology of the selected liquid drug,on the other hand, the liquid drug has a dual therapeutic action:  
A physical effect due to the injected volume and a therapeutic effect, as in Mesopuncture, due to the pharmacological properties of the liquid drug injected:


For example, injecting locally an anesthetic, into the TPs, allows stretching of the involved muscles painless.
Anesthetic, Botox, steroids... are commonly used.
Many other liquid drugs may be used, when the TP is, at the same time, an Acupuncture Point_ AP and a TP, WN and Mesopuncture are then combined.
It is also possible to use liquid drugs without therapeutic effect, such as distilled water, saline or whose action is integrated into the physiological mechanism of recovery of the initial state of health, such as trace elements, homeopathic remedies…


The needle, liquid drugs and BMN
Wet needling performed with the BMN, allows performing in the same TP, a mechanical deactivation, by the BMN needle, supplemented by a liquid deactivation with the same device, by the liquid drug from the reservoir, injected into the TP; adding the anesthetics or therapeutic properties (ant-inflammatory, vitamin, etc.) of this liquid drug to the double deactivation.




  • Injection of a chemical, popular among many practitioners, is not necessary; however, the analgesic or therapeutic effect of chemical provides an additional effect while keeping the therapeutic effect of the needle itself for example to avoid the needle insertion pain in the already painful TP, a fortiori when this insertion must be repeated many times.
  • It seems that Wet Needling is more practical and rapid, since it causes fewer disturbances than Dry Needling.


WN is more effective than Acupuncture or DN for certain types of musculoskeletal pain.
WN shortens the needle insertion pain, in the already painful TP, a fortiori when this insertion must be repeated many times.
WN appears to be the quickest treatment for new TPs formations, with chronic TPs sites requiring multiple and frequent, injections.  
WN could be selectively used in TPs recurrent or resistant to conventional treatment, caused perhaps by


  • Physical factors: Postural stress, repetitive movement, vitamin and mineral deficiencies… 
  • Psychological factors such as stress, tension and anxiety….