Last Updated on November 11, 2022
Also called a myofascial trigger point, the trigger point is a hyperirritable spot in skeletal muscle. These are associated with palpable nodules in taut bands of muscle fibers. It is believed that palpable nodules are tiny contraction knots and a common cause of pain.
Myofascial pain syndrome is a common painful muscle disorder characterized by myofascial trigger points.
This is different from fibromyalgia syndrome, which involves multiple tender points, though the two pain syndromes may occur together. [See below for differentiation between trigger spots and tender points
Trigger spots are a major cause of pain and dysfunction. They produce pain locally and in a referred pattern.
Pressing the point may cause local tenderness, referred pain, or local twitch response.
The term was coined in 1942 by Dr. Janet Travell.
Trigger spots often accompany chronic musculoskeletal disorders.
Repetitive microtrauma may contribute to their formation and the pain may affect muscle motion. Most often these are found in muscles that maintain postures such as the neck, shoulders, and pelvic girdle.
Trigger-point injection has been shown to be one of the most effective treatments.
Characteristic Features
A typical trigger spot or point is said to have the following characteristics
- Pain related to a discrete, irritable point in skeletal muscle or fascia, not caused by acute local trauma, inflammation, degeneration, neoplasm, or infection.
- The painful point can be felt as a tumor or taut band in the muscle
- The lesion is tender to palpate
- Twitch response
- Visible or palpable contraction or dimpling of the muscle and skin
- Occurs as the taut band or tense fibers contract when pressure is applied.
- Referred pain on stimulation of the trigger point
- Pain in the affected muscle and sometimes in seemingly unrelated parts of the body.
Not all patients have all the symptoms though,
Types
Trigger points can be active or latent, depending on their clinical features.
- Active
- Pain at rest
- Tender
- Radiating referred pain
- Latent
- No spontaneous pain
- Muscle stiffness or weakness
Not all may have these classical features though.
Key & Satellites
A key trigger point is one that has a pain referral pattern along a nerve pathway that activates a latent trigger point on the pathway or creates it.
A satellite trigger point is one that is activated by a key trigger point.
Successfully treating the key trigger point often will resolve the satellite and return it from being active to latent, or completely treating it too.
Primary & Secondary
A trigger point in many cases will biomechanically activate a secondary one in another structure. The original one is called the primary.
Treating the primary does not treat the secondary trigger point.
What Activates A Trigger Point?
- Acute or chronic muscle overload
- Activation by other trigger points
- Psychological distress
- Direct trauma to the region
- Radiculopathy ( Pain due to compression /irritation of nerve root)
- Smoking
What are Tender Points and How to Differentiate Them from Trigger Points?
In contrast to the trigger points, [areas of muscle that are painful to palpation, taut bands, and presence of referred pain], tender points are areas of tenderness occurring in muscle, muscle-tendon junction, bursa, or fat pad.
Widespread tender points are seen in fibromyalgia.
The two may occur together and must be differentiated as trigger points respond well to injections.
Here are the main differentiating features
Trigger Points
- Single or multiple
- Symptoms
- Local tenderness
- Taut band
- Local twitch response – A twitch-like reflex occurs in the involved muscle
- Jump sign- On palpation patient moves involuntarily and jerks of some other part of the body that is not being palpated such as the head or shoulders. Suggests intense pain.
- May occur in any muscle
- Referred pain present around the point
Tender Points
- Often multiple
- Symptoms
- Local tenderness
- Symmetrical location [Around joint, bursae, etc]
- No referred pain but may hasten pain sensitivity of the body
Pathogenesis and Causes
The mechanism behind the formation of trigger points is not understood well. The following have been thought to contributing
- Acute trauma like a sprain
- Repetitive microtrauma
- Lack of exercise
- Poor posture over a prolonged period- for example sitting in a chair that lacks proper back support
- Vitamin deficiencies
- Sleep disturbances
- Joint problems may
- Post-surgery tissue/scar tension
Diagnosis
Diagnosis is mainly clinical. On palpation, the following suggests the likelihood of a trigger point.
- Pain patterns and tenderness
- A taut band or hard nodule
- A twitch response when running a finger perpendicular to the muscle’s direction.
How to Locate a Trigger Point
On palpating the muscle for the lesion a palpable taut band or cord of tense muscle fibers approximately 1-4 mm in diameter is felt.
The point of maximum tenderness on this band is the point.
- Firm pressure on the point would reveal the referred pain pattern.
- Local twitch response
- Local muscle twitch when the trigger point is rolled under the fingers or a needle is inserted into the trigger area
- Result of the contraction of the muscle fibers in the taut band
- Jump Sign
- Jump or involuntary reflex–like the movement of the patient when the trigger point is pressed.
- The jump is disproportionate to the amount of pressure exerted
- Is reproducible
- Thought to correspond to the degree of irritability
These points should be differentiated from the other tender points
Treatment
There are many options for the treatment are
- Dry Needling
- Local anesthetics/steroid injection
- Non-invasive treatments
- Manual massage
- Mechanical vibration
- Ultrasound
- Electrostimulation
- Ischemic compression
- Low-Level Laser Therapy
- Stretching techniques
Dry needling and intralesional injections have a good outcome and are preferred over noninvasive methods.
Dry Needling
In dry needling, a filament needle [acupuncture needle] is inserted into the skin and muscle aiming band. It can be done at the superficial or deep tissue level.
After deactivation of the points, muscle and fascial stretching should be done.
Dry needling is thought to be effective by
- Stimulation of a local twitch response reduces the concentration of painful substances in the chemical environment near myofascial trigger points.
- Muscle regeneration
- The release of intracellular potassium may depolarize and disrupt nerve conduction.
Some studies have reported dry needling to be only slightly better than placebo.
Trigger Point Injections
Injections are an effective treatment modality for inactivating trigger points and providing prompt relief from myofascial pain syndrome symptoms.
The injection includes the administration of local anesthetics like lidocaine or procaine. The use of saline has been recommended for patients allergic to anesthetic agents.
After the procedure, the muscle is stretched.
Activity modification and exercises are included in the treatment regime after an injection.
Activity Modification
Ask the patient to rest the affected areas for one to two days after the injections.
As long as injection soreness is there, strenuous activities should be avoided but range of motion exercises are encouraged.
In the long run, patient needs to recognize and avoid the pain-provoking activities and muscle stressing movements. Learning to use muscles well and with proper alignment is key to long-lasting relief.
Exercise
After the inactivation of the points and resolution of rest pain, a carefully graded exercise program is introduced.
This includes stretching exercises of the involved muscles, improved conditioning, and increased strength reducing the likelihood of developing trigger points.
References
- Alvarez DJ, Rockwell PG. Trigger points: diagnosis and management. Am Fam Physician. 2002 Feb 15. 65(4):653-60. [Link]
- Ge HY, Nie H, Madeleine P, Danneskiold-Samsøe B, Graven-Nielsen T, Arendt-Nielsen L. Contribution of the local and referred pain from active myofascial trigger points in fibromyalgia syndrome. Pain. 2009 Dec 15. 147(1-3):233-40.
- Lucas N, Macaskill P, Irwig L, Moran R, Bogduk N. Reliability of physical examination for diagnosis of myofascial trigger points: a systematic review of the literature. Clin J Pain. 2009 Jan. 25(1):80-9.
