Ortigosa Solorzano, E.*
Hospital Universitario de Getafe, Anesthesia, Madrid, Spain
ESRA Academy. Ortigosa Solorzano E. Sep 16, 2017; 196208
Esperanza Ortigosa Solorzano
Esperanza Ortigosa Solorzano
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Dr Esperanza Ortigosa  


Myofascial pain syndrome (MPS) is  a prevalent and  frequent cause of visits to primary care physicians and pain clinics. 

Muscle pain as a result of trauma, injury, overuse, or strain, frequently resolves in a few weeks with or without medical treatment. In some cases, however, it persists long after resolution of the injury and it may even refer to other parts of the body, usually contiguous or adjacent rather than remote. This heralds the sensitized state, one of the features of a chronic pain disorder, in which the pain itself is the pathology and requires medical intervention for its resolution.

The term “myofascial” indicates that both muscle and fascia are likely to be contributors to the symptoms1.

For many clinicians and investigators, the finding of  myofascial trigger points (MTrPs)  is required to assure the diagnosis of (MPS).

MTrPs are hyperirritable areas in a taut band of muscle tissue or fascia that are tender when compressed, and give rise to referred pain. They are commonly associated with limited range of motion, fatigue, impaired muscle coordination, and vegetative phenomena2


Common etiologies of myofascial pain may be from direct or indirect trauma, spine pathology, exposure to cumulative and repetitive strain, postural dysfunction, vitamin deficiencies, sleep disturbances, joint problems and physical deconditioning2.

Different studies have demonstrated that MTrPs are associated with several pain conditions, including radiculopathies, disk pathology, tendonitis, craniomandibular dysfunction, migraines, tension type headaches, carpal tunnel syndrome, computer-related disorders, whiplash-associated disorders, spinal dysfunction, post-herpetic neuralgia, complex regional pain syndrome etc…



The pathophysiology of MTrPs  is incompletely understood, and a number of morphological changes, neurotransmitters, neurosensory features, electrophysiological features, and motor impairments have been implicated in  its pathogenesis:

  • Morphological changes: A significant increase in stiffness has been found within the taut band of MtrPs.
  • Neurotransmitters: Higher levels of neuropeptides (e.g., substance P or calcitonin gene-related peptide), catecholamines (e.g., norepinephrine), and proinflammatory cytokines (e.g., tumor necrosis factor alpha, interleukin 1-beta, interleukin 6, and interleukin 8) have been found in active trigger points. 
  • Neurosensory features: Spreading referred pain, hypersensitivity to nociceptive stimuli (hyperalgesia) and non-nociceptive stimuli (allodynia), mechanical pain sensitivity, sympathetic facilitation of mechanical sensitization, facilitation of local and referred pains, and attenuated cutaneous blood flow responses.
  • Electrophysiology: Some studies have found spontaneous electrical activity, attributed to an increase in miniature endplate potentials and excessive acetylcholine release in MTrPs, although future studies are needed to confirm these findings.
  • Motor impairments: MTrPs can induce changes in normal muscle activation patterns and result in motor dysfunction. A recent hypothesis proposes that central nervous system-maintained global changes in α-motor neuron function, resulting from sustained plateau depolarization, underlie the pathogenesis of MTrPs. A continuum of muscle nociceptor sensitization between active trigger points (spontaneously painful) and latent trigger points (painful only after evoked stimulus) may explain its different behavior3.

Kumbare et al 4 have described  that once a  trigger point has developed, decreased ATP and glycogen concentration, increased release of substance P, acetylcholine, bradykinin, serotonin, and prostaglandin occur within the MTrPs.
Besides, these are associated with increased receptor sensitivity that may overstimulate local afferent sensory nerves causing the perception of pain in a trigger point 5,6,7 . These latter issues are part of central sensitization and neurogenic inflammation.


 David Simons was the first one  to describe the criteria for the identification of MTrPs by palpation such as a taut band, local tenderness, pain recognition, referred pain, a local twitch response and the “jump sign.” 

 MTrPs characteristically elicit referred pain when stimulated. The duration of this  pain is variable (second, hours, or days).  It is perceived as a deep, aching, and burning pain, although sometimes it may be noticed  as superficial pain. The referred pain may spread caudally or cranially and the intensity and expanded area  are positively correlated with the degree of the  trigger point activity. There has been described different types of  MTrPs  according to location, tenderness, and chronicity as central (or primary), satellite (or secondary), attachment, diffuse, active (spontaneously painful)  and inactive or latent (painful only after evoked stimulus). 


     The diagnostic of MPS is still based on clinical criteria. However, because many of these  criteria are nonspecific and overlap with other causes of regional pain, diagnosis can be difficult.
Recent studies  have agreed that point tenderness and reproduction of pain are key to diagnosis, while autonomic symptoms are unnecessary.
Rivers et al 8,4 used  the results of their survey and proposed the following diagnostic criteria based on physician consensus:

1. A tender spot is found with palpation, with or without referral of pain (“trigger point”) and;

2. Recognition of symptoms by patient during palpation of tender spot and;

3. At least three of the following:

 a. Muscle stiffness or spasm.

 b. Limited range of motion of an associated joint.

 c. Pain worsens with stress.

 d. Palpation of taut band and/or nodule associated with a tender spot. 

There are some tools that can help us with the diagnosis:  

- Electromyographic studies have revealed spontaneous electrical activity generated at MTrPs loci that was not seen in surrounding tissue. Using a needle with a monopolar electrode  connected to a device that amplifies  electromyographic  signals from the muscle and transforms them into sounds can provide us an  acoustic feedback in order to help physicians locate areas of muscle activity.

However, there is disagreement in electromyography and physiology literature on the significance of abnormal motor endplate potentials and endplate noise.

- In the last years ultrasound  has been used to identify MTrPs. Trigger points have been shown to be mainly hypoechogenic but also hyperechogenic spots with fusiform or elliptical shape. Furthermore, normal patients and patients with tender points without fibromyalgia syndrome, also exhibited similar hypoechogenic spots as seen in MTrPs. This, together with the interrater variability, muscle, fasciae anisotropy, and the difficulty in the visualization of deep structures, has made researchers look for additional tools to improve the diagnostic accuracy. Blood flow in the neighborhood of MTrPs has been assessed using  Doppler imaging and a grading scale has been proposed. Preliminary findings show that active MTrPs have significantly higher peak systolic velocities and negative diastolic velocities compared with latent MTrPs and normal muscle sites when measured in the vicinity. 

- Ultrasound Elastography in its different modalities, vibration sonoelastography, strain elastography and the new shear-wave sonoelastography, may evaluate regional stiffness and it is a useful tool that can help us with the diagnosis and treatment of MTrPs. The gray- or color-scale encoding is adjustable by the user. Typically, red is used to represent softer tissues, blue represents harder tissues, and yellow or green represent tissues of intermediate elasticity.  



Management of MTrPs is multimodal.

Travell and Simons were not the first  to identify and develop a treatment for MTrPs, but they were  among the first ones to recognize the relationship of the trigger points to MPS.  They proposed that deactivating MTrPs was an essential component to successfully treating MPS.

The most commonly used interventions are as follows:

Among the invasive therapies, scientific articles report mixed results. Generally, dry needling, anesthetic injection, steroids, and botulinum toxin-A  of the MTrPs, have all been shown to provide pain relief.

While the etiology of MPS and the pathophysiology of MTrPs are not yet fully understood, some investigators are suggesting that treatments should focus not only on the MTrPs, but also on the surrounding environment (e.g., fasciae, connective tissue, etc.). 

In this sense ultrasound-guided interfascial block, a known regional anesthetic technique, is an approach in myofascial pain with mínimum traumatic damage to the muscles. Local anesthetics injected in the interfascial planes provide direct blockade of somatic nerve endings and perhaps sympathetic nervous fibers, both also piercing each fascia and giving profound long-lasting muscle relaxation and pain relief9,10,11. The technique requires the aid of ultrasound imaging and a short bevel needle to be accurate enough, as the pop-up feeling of the needle crossing the fascia is not reliable (Figure 1).

Figure 3:  Interfascial block. LA: local anesthetic,  S: steroids

Figure 1  Interfascial block. LA: local anesthetic,  S: steroids

Cho et al have combined interfascial block with pulsed radiofrequency with good results11

Other treatments are: massage, ischemic compression, pressure release, and other soft tissue interventions.

MTrPs injections are usually safe and effective. However , although very rare , there  have been reported some complications resulting in pneumothorax, epidural abscess, skeletal muscle toxicity, and intrathecal injection12. Two reviews of the American Society of Anesthesiologists closed claims analysis have shown increasing number of complications related to interventional long-term pain management, with MTrPs injections being associated mainly with pneumothorax,13,14,.

Ultrasound may, in theory, reduce the risk of complications by identifying potentially hazardous structures in the path of the needle, especially in cases where the MTrPs are in deep fasciae or muscular layers. 


MPS is a common musculoskeletal pain disorder.  It is  characterized by local and referred pain, perceived as deep and aching, and by the presence of MTrPs in any part of the body.  MTrPs are hyperirritable areas of muscle tissue or fascia that are tender when compressed and give rise to referred pain.

The diagnostic of MPS is still based on clinical criteria. However, because many of these  criteria are nonspecific and overlap with other causes of regional pain, diagnosis can be difficult.

The clinical utility of ultrasound guidance lies in its potential to increase the safety and efficacy of needling procedures. Compared with landmark-based techniques,

ultrasound  guided procedures can ensure accurate needle placement within a specific muscle group, which may be particularly advantageous for deeper target. It also  decreases adverse events while offering the maximum benefit to the patient.


1.  Simons D, Travell J, Simons L. Travell and Simons’ myofascial pain and dysfunction: The trigger point manual. 2nd ed. Baltimore: Williams & Wilkins; 1999. 
2.  Shah JP, Thaker N, Heimur J, Aredo JV, Sikdar S, Gerber L. Myofascial Trigger Points Then and Now: A Historical and Scientific Perspective. PM R. 2015 July ; 7(7): 746–761. 

3.   Hocking MJL. Exploring the central modulation hypothesis: do ancient memory mechanisms underlie the pathophysiology of trigger points? Curr Pain Headache Rep. 2013;17(7):931–938.

4.  Kumbare D, Singh D, Rathbone H A, Gunn M, Grosman-Rimon L, Vadasz B, Clarke H, Peng PWH. Ultrasound-Guided Interventional Procedures: Myofascial Trigger Points With Structured Literature Review. Reg. Anesth.Pain Med. 2017 May/Jun;42(3):407-412.

5.  Jensen R, Rasmussen BK, Pedersen B, Olesen J. Muscle tenderness and pressure pain thresholds in headache. A population study. Pain. 1993;52:193–199.

6. Simons DG. Myofascial pain syndrome due to trigger points. In: Goodgold J, ed. Rehabilitation Medicine. St Louis, MO: Mosby Co; 1988:686–723. 

7.  Thompson JM. The diagnosis and treatment of muscle pain syndromes. In: Braddom RL, ed. Physical Medicine and Rehabilitation. Philadelphia, PA: WB Saunders; 2000:934–956.

8.  Rivers WE, Garrigues D, Graciosa J, Harden RN. Signs and symptoms of myofascial pain: an international survey of pain management providers and proposed preliminary set of diagnostic criteria. Pain Med. 2015;16:1794–1805.

9.  Mayoral V, Domingo-Rufes T, Casals M, Serrano A. Narváez J. Sabaté A. Myofascial trigger points: New insights in ultrasound imaging. Techniques in regional  anesthesia and pain management 1 7(2013)150-54.

10.  Ortigosa E, Castellanos R. Uso de la Ecografía en la detección de puntos gatillo. In: Ortigosa E. Ecografía en el tratamiento del Dolor Crónico. 1st ed. Aelor SL. 2017: 567-575.

11.  Cho T, Cho YW, Kwak SG, Chang M. Comparison between ultrasound-guided interfascial pulsed radiofrequency and ultrasound-guided interfascial block with local anesthetic in myofascial pain syndrome of trapezius muscle. Medicine (Baltimore). 2017 Feb; 96(5).

12.  Domingo T, Blasi J, Casals M, Mayoral V, Ortiz-Sagristá JC, Miguel-Pérez M. Is interfascial block with ultrasound-guided puncture useful in treatment of myofascial pain of the trapezius muscle?. Clin J Pain 2011 May;27(4):297-303. 

13.   Metzner J, Posner KL, Lam MS, Domino KB. Closed claims' analysis. Best Pract Res Clin Anaesthesiol. 2011;25(2):263–276.

14.  Chim D, Cheng PH. Ultrasound-guided trigger point injections. Tech Reg Anesth Pain Manag. 2009;13(3):179–183.







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