Introduction to Myofascial Pain

Original Editor - Carin Hunter based on the course by Rina Pandya
Top Contributors - Jess Bell, Carin Hunter, Kim Jackson, Lucinda hampton, Robin Tacchetti and Tony Lowe

Introduction

Fascia is a connective tissue structure that surrounds muscles, groups of muscles, blood vessels, and nerves. It binds some structures together, while permitting others to slide smoothly over each other.

Fasciae are dense, regular connective tissues, which contain closely packed bundles of collagen fibres. These fibres are oriented in a wavy pattern, which runs parallel to the direction of pull. Because of this arrangement, fasciae are flexible structures that can withstand significant uni-directional tensile forces.

Ligaments and tendons are similar to fascia as they too are made of collagen. However, ligaments join bone to bone, tendons join muscle to bone and fasciae surround muscles or other structures.

The video below provides a fascinating introduction to fascia.

Structure

Fascia creates different, independent layers at varying depths, from the skin to the periosteum, thus forming a three-dimensional mechano-metabolic structure.

Fascia

• Consists of solid and liquid components:
  • Solid components: muscle, bone, cartilage and adipose tissue
  • Liquid components include: blood and lymph

Myofascia

• Includes contractile muscle and connective tissues:
  • End thickenings of the myofascia attach muscles to bones. They are, therefore, able to guide the skeletal system through muscular contractions
  • The nerve, vascular and lymphatic systems are enclosed in multiple layers of fascia. Thus, different tissues are linked together by the fascia

Myofascial Pain

The liquid fascia (blood and lymph) can be a source of myofascial pain due to:

• Flow velocity
• Direction
• Type of flow

Myofascial pain can be caused by any structure that is tangled in the myofascia:

• Nerves
• Muscles
• Connective tissue

Alternative Definitions

Fascia Nomenclature Committee (2014)

“The fascial system consists of the three-dimensional continuum of soft, collagen containing, loose and dense fibrous connective tissues that permeate the body. It incorporates elements such as adipose tissue, adventitia and neurovascular sheaths, aponeuroses, deep and superficial fasciae, epineurium, joint capsules, ligaments, membranes, meninges, myofascial expansions, periosteum, retinacula, septa, tendons, visceral fasciae, and all the intramuscular and intermuscular connective tissues including endo-/peri-/epimysium. The fascial system interpenetrates and surrounds all organs, muscles, bones and nerve fibers, endowing the body with a functional structure, and providing an environment that enables all body systems to operate in an integrated manner.”

FORCE (2013) - Foundation of Osteopathic Research and Clinical Endorsement.

“The fascia is any tissue that contains features capable of responding to mechanical stimuli. The fascial continuum is the result of the evolution of the perfect synergy among different tissues, liquids and solids, capable of supporting, dividing, penetrating, feeding and connecting all the regions of the body, from the epidermis to the bone, involving all its functions and organic structures. This continuum constantly transmits and receives mechanometabolic information that can influence the shape and function of the entire body. These afferent/efferent impulses come from the fascia and the tissues that are not considered as part of the fascia in a biunivocal mode. In this definition, these tissues include: epidermis, dermis, fat, blood, lymph, blood and lymphatic vessels, tissue covering the nervous filaments (endoneurium, perineurium, epineurium), voluntary striated muscle fibers and the tissue covering and permeating it (epimysium, perimysium, endomysium), ligaments, tendons, aponeurosis, cartilage, bones, meninges, and tongue"

Hypotheses for Myofascial pain

1. Trigger points:
   1. Active: pain without movement
   2. Passive or latent: painful with palpation, vague, non-localised
2. Constant microtrauma to the muscle→ depletes ATP → alters mechano-metabolic environment → increases nociceptive impulses to the brain→ peripheral sensitisation in acute phase and central sensitisation chronically (potassium, prostaglandins, histamine, kinins) → increase in ACH at synaptic end plate→ continuous contraction→ depletes ATP → inflammation
3. Change in connective tissue due to inflammation →  fibroblasts transform to myofibroblasts → shortening of tissue and increase in tone→ nociceptive stimulus → alters polarisation of muscle fibers → muscle contraction
4. Altered mechano-metabolic environment → thickening of extracellular matrix → fascia has difficulty sliding→ harder for muscle to contract →the nerve endings of the fascia in the most viscous area stretch, so that they are constantly activated, creating a trigger point
5. Alteration of blood flow (increase in systolic velocity, decrease in diastolic velocity) → alters morphology and function of capillaries→ ischaemia → activates type IV nerve endings → myofascial pain

Differential Diagnosis for Myofascial Pain

• Fibromyalgia: a chronic pain condition of uncertain aetiology. Individuals with fibromyalgia experience a number of changes in their myofascial system, including pain and fatigue. It has been found that the fascia may be involved in stimulating inflammation and fat cell production. However, while myofascial pain can cause an inflammatory environment and local pain, fibromyalgia is not localised.

• Chronic pelvic pain: pain must be present for at least 6 months to be classified as chronic pelvic pain. Pain may be continuous or intermittent. It is not necessarily influenced by menstruation / intercourse (in women). Ultrasound examinations are used to determine if an individual's pain is due to muscular processes or organic dysfunction. While menstruation pain can be linked to specific times, days, hormones etc, myofascial pain is not dependent on these factors.

• Temporomandibular Joint (TMJ): TMJ pain can be associated with myofascial pain, but other structures can also refer pain to the TMJ. If pain does not improve after manual techniques (i.e. trigger point release) or medication, this pain could be a sign of cardiac ischaemia.
• Eagle's Syndrome: characterised by abnormality of the styloid process. Patients present with recurrent throat or neck pain, which radiates to the ear. They may also have dysphagia. Myofascial pain should improve with tissue treatment. If it does not, then the cause must be investigated further.
• Inflammation: Inflammation of tendons or other connective tissue formations (i.e. fasciitis, tendinopathies etc) tend to affect a very specific anatomical area. There is often a clear aetiology and palpation, special tests and symptoms tend to point to a specific diagnosis. If the pain is more global, it is necessary to start to look outside the diagnostic box at the myofascia.

History Taking

A patient's history can provide clues that the myofascia could be implicated in his / her pain. The following table lists aspects that need to be considered during the assessment process.

Table 1. Factors that should be considered in a patient's history.

Mechanical	Psychological	Systemic/ metabolic	Other
Mechanical forces (e.g. prolonged standing)	Stress	Hypothyroidism	Infectious disease
Scoliosis (leads to imbalanced, unequal forces)	Anxiety	Iron deficiency	Parasitic disease
Limb length discrepancy (leads to unequal forces)		Vitamin D deficiency	Rheumatic disease
Muscle hypertrophy (overactivity in some muscles)		Vitamin C deficiency	Hyperalgesia
Repetitive microtrauma		Vitamin B12 deficiency	Statins