Trigger Points

Question 1

How do muscles work?

Answer 1

Sliding filament theory
Muscle Fibre  Myofibrils  Actin and Myosin Filaments
Actin filaments are anchored to Z-lines; the space between 2 Z-lines = sarcomere
Myosin Filaments ”walk” along the actin filaments with their cross bridges using energy from ATP.
“Walking” pulls actin filaments together  pulls Z-lines together  shortening of the sarcomere
Sarcomere shortens = muscle fibre shortens

The more fibres that contract at the same time = greater force of contraction

Question 2

What are trigger points?

Answer 2

Myofascial pain refers to a specific form of soft-tissue dysfunction that result from irritable foci (myofascial trigger points) within skeletal muscles and their ligamentous junctions.

Question 3

What is the history of trigger points?

Answer 3

The clinical science of trigger points can be traced to the pioneering work of Kellgren in the 1930s, with his mapping of myotomal referral patterns of pain resulting from the injection of hypertonic saline into muscle and ligaments.

Most muscles have characteristic myotomal patterns of referred pain; this feature formed the basis of the clinical recognition of myofascial trigger points, in the form of a tender locus within a taut band of muscle that restricts the full range of motion and refers pain when stimulated.
(Shah et al., 2015)

J. Travell was influenced by this work and now her work on myofascial pain, dysfunction and trigger points is the most comprehensive to date

Question 4

What is myofascial pain?

Answer 4

pain arising from muscles or related fascia.

Question 5

What is an active trigger point?

Answer 5

an active trigger point causes spontaneous pain at rest, with an increase in pain on contraction or stretching of the muscle involved. There is often a restriction of its range of motion. Pain on motion may cause pseudo-muscle weaknesses due to reflex inhibition.

Question 6

What is a latent trigger point?

Answer 6

differs from an active MTrP in that the nociceptors have become activated and sensitized but not enough to cause spontaneous pain to develop. However, a latent trigger point may restrict range of movement and result in weakness of the muscle involved and refer pain on compression. It is therefore possible to find latent MTrP in asymptomatic individuals.

Question 7

What is a primary trigger point?

Answer 7

the MTrP(s) whose nociceptor activity in a muscle or muscle group of muscles is primarily responsible for the pain syndrome, (can be active or latent).

Question 8

What is a Secondary MTrP?

Answer 8

these develop elsewhere within the initially affected muscle or muscles group or the synergists or antagonist muscle of the initially affected muscle due to the overload or weakness caused by the primary MTrP.
Therefore, the myofascial pain syndrome may spread to involve a large area or region of the body.
This increases the possibility of sensitizing the nervous system, leading to chronicity. Together with difficulties in accurately diagnosing the problem, due to the pain pattern and also problems associated with treating the condition effectively, (can be active or latent).

Question 9

What is a Satellite MTrP?

Answer 9

Satellite MTrP: these are MTrPs that become active when the muscle in which they are present is situated in the referred pain pattern of another MTrP.

Like secondary MTrP the myofascial pain syndrome will then spread to involve a large area or region of the body increasing the possibility of sensitizing the nervous system, leading to chronicity.

Together with difficulties in accurately diagnosing the problem due to the pain pattern and problems associated with treating the condition effectively

Question 10

What is a ligamentous MTrP?

Answer 10

are found in lax, stretched ligaments as a result of aging, trauma and/or poor posture, particularly those ligaments involved in the support of the axial (vertebral column and pelvis) or appendicular (upper or lower extremities) skeleton.
These MTrPs are extremely sensitive to further stretching and may be fired by prolonged maintaining of a stressful position or sudden movements to an extreme range. They are usually associated with weak, tight muscles.

Question 11

What is a periosteal MTrP?

Answer 11

are found on the surface of bone usually at the site of ligament or tendon attachment and related to tension on that area from a stretched ligament or tendon.

Question 12

What are the The Characteristic Features of a Myofascial Trigger Point?

Answer 12

Focal point of tenderness to palpation of the muscle involved
Reproduction of referred pain on continued (with 5 sec) pressure over trigger point
Normally a dull achy deep pain of varying intensity over a characteristic pain pattern.
Palpation reveals induration of the adjacent muscle i.e. a “taut band” of muscle
Local twitch response
Restricted range of movement in the muscle involved
Often pseudo-weakness of the muscle involved (no atrophy)
Often pain on muscle contraction
Possible dysaesthesia (distortion of normal sense)

Question 13

What is pain referral?

Answer 13

Convergence-facilitation and convergence-projection theories

Two theories originally put forward to explain visceral referred pain have also been suggested to apply to MTrP and muscle pain.
Theory  there is extensive convergence of sensory afferent input from various structures i.e. muscle, skin and viscera, into the dorsal horn which is not sufficiently specific for the brain to be able to accurately distinguish between the site of origin.
Therefore, in MTrP  the validity of this mechanism has been questioned  patients usually have little difficulty in determining that the pain is arising from the muscle

Question 14

What is central sensitisation?

Answer 14

Animal experiments have shown that the dorsal horn neurons with sensory afferent inputs from nociceptors in muscle can change both the size and number of their receptive fields in response to the application of a noxious stimulus to the muscle.
It has been suggested that the referral of MTrP pain may be due to the neuroplastic changes that develop in the dorsal horn neurons in the phenomenon known as central sensitisation.
Part of this process is the enlargement and increased sensitivity of dormant nociceptive neurons receptive fields and the concomitant opening of previously silent synaptic connections.

Question 15

What is Myofascial Pain Syndrome (MPS) ?

Answer 15

is a pain condition originating from muscle and adjacent fascia.
Presentation = localised pain, restricted area or referred pain in various patterns, trigger points (just one or a bunch clumped together)
Acute and Chronic MPS.
Acute usually resolves on it’s own or with manual therapy
Chronic MPS has a worse prognosis and can last for 6months or more

Suggested Pathophysiology:
Repetitive or prolonged activity can cause overloading of the muscle fibres leading to muscle hypoxia and ischemia.
Intracellular Ca2+ pumps are dysfunctional due to energy depletion. This induces sustained muscle contraction which results in the development of taut bands.
Inflammatory mediators from muscle injury contribute to muscle pain and tenderness

Question 16

What are clinical characteristics of myofascial pain?

Answer 16

Myofascial pain has certain clinical characteristics that aid in considering this diagnosis.
Deep aching pain,
Area feels stiff; (sometimes described in terms of joint stiffness)

Aggravating factors:
using the involved muscle(s),
psychological stressors, anxiety, cold,
postural imbalance (staying in the same posture for a prolonged time).
Radiation from a trigger point may be described in terms of paraesthesia and thus mimic the symptoms of a cervical or lumbar radiculopathy.

Over time muscle weakness, secondary to disuse, may present with the symptoms, weakness, poor coordination, and reduced work tolerance, fatigue and sleep disturbance.
Patients with myofascial pain involving the neck and face muscles have been reported to have the symptoms of dizziness, tinnitus and poor balance (Travell & Simons 1983, Borg-Stein & Simons 2002)
Importantly, referred pain from a trigger point does not follow a nerve root distribution (i.e. it is not dermatomal).

Palpation
Compression for > 5seconds = pain in referred distribution that reproduces the patient’s symptoms
rope-like “taut band”.
Snapping this band often produces a localized twitch response of the involved muscle (superficial muscles)
(Both the phenomenon of referred pain and local twitch response can be elicited by needling the trigger point).

Question 17

What factors are predisposing to trigger-point formation?

Answer 17

In order to effectively treat myofascial pain syndromes, it is mandatory to include a thorough evaluation of potential contributory issues and triggers.
Factors commonly cited as predisposing to trigger-point formation include
de-conditioning,
prolonged posture in one position,
repetitive mechanical stress,
psychological stressors,
mechanical imbalance,
joint disorders
non-restorative sleep.

Question 18

What is treatment for myofascial pain syndromes?

Answer 18

Pharmacological:
Anti-inflammatory meds
Analgesic meds
Topical creams

Non-pharmacological:
Post-Isometric Relaxation
Trigger Point Compression
Muscle Energy Techniques (MET)
Spray and stretch
Dry Needling
Massage

Question 19

What causes MTrPs?

Answer 19

Trauma
The usual reason for MTrP activity is the subjection of muscle to the high-intensity stimulation provided by trauma.
This may be in the form of direct injury to a muscle or by the sudden or repeated overloading of it.
Alternatively, it may develop when a muscle is subjected to repeated episodes of micro-trauma, such as repetitive strain injury.

Anxiety

Not uncommonly a patient who, because of anxiety, holds a group of muscle (i.e. shoulder girdle) in a persistently contracted state develop MTrP (possible through micro trauma).
Another possibility is that it is brought about as a result of psychological determined stimulation of brain-stem structures.
This is because neurons in the brain stem‟s reticular tissue have axons that project upwards to the thalamus and hypothalamus and axons that project downwards to the spinal cords motor neurons.
These in turn have connections with MTrPs motor endplates.

Muscle weakness

MTrP may develop in muscle that have become weakened and overloaded such as a result of neurological disease, injury, arthritis, de-conditioning and possible postural syndromes.
With stroke MTrPs may develop during the recovery stage when weakened muscles become overloaded during attempts to restore movement to them.
This myofascial pain needs to be differentiated from post-stroke neuropathic pain which is usually burning in nature.

MTrPs may develop when muscles are exposed to adverse environmental conditions such as dampness, draughts, excessive cold or heat.