Trigger Points
Trigger Points
Myofascial trigger points (TrPs) are hyperirritable spots within skeletal muscle, often palpable as nodules in taut bands of muscle fibres. They are a primary component of myofascial pain syndrome (MPS), a condition characterised by acute or chronic muscle pain and associated connective tissue discomfort. Understanding TrPs is crucial for healthcare professionals, particularly manual therapists, as they play a significant role in musculoskeletal pain and dysfunction.
Types of Trigger Points
Trigger points are generally classified into two main categories: active and latent.
Active Trigger Points: These points cause spontaneous pain without any external stimulus. The pain is often persistent and can limit daily activities. Palpation of active TrPs reproduces the patient's pain complaint, and the pain may radiate in a specific pattern associated with the muscle involved.
Latent Trigger Points: These are asymptomatic and do not cause spontaneous pain. However, they can restrict movement and cause muscle weakness. Pain is elicited only upon palpation. Latent TrPs can become active due to factors such as muscle overload, stress, or injury.
Neurophysiology of Trigger Points
The exact mechanisms underlying TrP formation and perpetuation are complex and not fully understood. However, several hypotheses have been proposed to explain their neurophysiological basis.
Integrated Hypothesis: This theory suggests that excessive release of acetylcholine (ACh) at the neuromuscular junction leads to sustained muscle fibre contraction. This continuous contraction results in localised ischaemia and hypoxia, causing an energy crisis within the muscle. The energy deficit impairs the function of the calcium pump, leading to an accumulation of calcium ions in the sarcoplasm and further sustained contraction. This cycle perpetuates the formation of a TrP.
Energy Crisis Hypothesis: According to this model, a combination of increased muscle demand and decreased energy supply leads to muscle fibre contracture. The resulting ischaemia and hypoxia cause the release of sensitising substances such as bradykinin, substance P, and prostaglandins, which activate nociceptors and contribute to pain.
Motor Endplate Hypothesis: This hypothesis posits that abnormal endplate potentials at the neuromuscular junction result in spontaneous electrical activity, leading to muscle fibre contracture and TrP formation. The sustained contracture compresses local blood vessels, leading to ischaemia and the release of pain-inducing substances.
Central Sensitisation: Chronic activation of TrPs can lead to central sensitisation, a condition where the central nervous system becomes hypersensitive to stimuli. This results in an exaggerated pain response to both noxious and non-noxious stimuli and may contribute to the persistence of pain in MPS.
Recent Advances in Trigger Point Research
Recent studies have utilised advanced imaging and biochemical analyses to better understand TrPs. For instance, microdialysis techniques have revealed elevated levels of inflammatory mediators and neurotransmitters, such as substance P and calcitonin gene-related peptide, in the vicinity of active TrPs. These findings suggest a significant role of biochemical factors in TrP pathophysiology.
Additionally, novel hypotheses have been proposed regarding TrP formation. One such theory suggests that a failure of protective regulatory mechanisms, particularly those involving feedback systems that prevent excessive muscle activity or calcium accumulation, may lead to TrP development. This perspective offers a new avenue for understanding the initiation of TrPs and potential therapeutic targets.
Satellite Trigger Points
Satellite trigger points are secondary trigger points that develop in muscles located near or within the referral pain zone of a primary trigger point. They are often a result of the chronic dysfunction caused by the primary trigger point. The development of satellite trigger points is an important consideration when diagnosing and treating myofascial pain, as they can complicate the clinical presentation and perpetuate pain syndromes.
Key Characteristics of Satellite Trigger Points:
Proximity to Primary Trigger Points:
Satellite trigger points typically form in muscles that are affected by the referred pain of a nearby active primary trigger point.Dependent on the Primary Trigger Point:
The activity and irritability of satellite trigger points are often influenced by the primary trigger point. Effective treatment of the primary trigger point can lead to the resolution of the satellite trigger points.Shared Referral Patterns:
Satellite trigger points may produce pain patterns that overlap or align with the referral pattern of the primary trigger point, making the distinction between the two challenging.Trigger Point Cascade:
If left untreated, a primary trigger point can initiate a cascade effect, creating multiple satellite trigger points in associated or compensatory muscles.
Example of Satellite Trigger Points:
A primary trigger point in the infraspinatus muscle can refer pain to the shoulder and down the arm. Prolonged dysfunction may lead to satellite trigger points forming in nearby muscles such as the deltoid or triceps brachii, which are within the referral zone.
Clinical Implications:
Diagnosis: It is crucial to identify whether a trigger point is primary or satellite, as treating only satellite points without addressing the primary source often leads to recurrence.
Treatment: A comprehensive approach is essential, focusing on the primary trigger point and addressing factors that perpetuate dysfunction, such as poor posture, repetitive strain, or muscle overload.
Preventing Recurrence: Patient education on ergonomics, stretching, and strengthening exercises can help prevent the reactivation of primary and satellite trigger points.
Research Insights:
Satellite trigger points exemplify how pain can radiate and spread through interconnected muscular and fascial systems. This phenomenon underscores the importance of understanding pain pathways and the interconnectedness of the myofascial network when managing myofascial pain syndromes.
Clinical Implications for Trigger Points Overall
For manual therapists, recognising and effectively managing TrPs is essential for alleviating musculoskeletal pain and restoring function. Treatment approaches may include manual therapies, dry needling, and patient education on posture and ergonomics. A comprehensive understanding of the types and neurophysiology of TrPs can enhance diagnostic accuracy and inform more targeted and effective treatment strategies.
There are several evidence-based approaches to treating trigger points, each targeting muscle dysfunction, pain relief, and the restoration of normal function. Here are seven effective methods:
1. Manual Therapy (Massage & Myofascial Release)
How it works:
Direct pressure, deep tissue massage, and myofascial release techniques help reduce muscle tightness, improve circulation, and break the pain cycle.
Sustained pressure applied to the trigger point (ischemic compression) can help reduce sensitivity and restore normal muscle tone.
Techniques:
Trigger Point Pressure Release (Ischemic Compression) – Sustained pressure applied to the TrP for 30-90 seconds until pain reduces.
Stripping Massage – Slow, deep strokes along the muscle fibres to break down adhesions.
Pin and Stretch Technique – The therapist applies pressure while the patient actively moves through a range of motion.
📌 Best for: Manual therapists, physiotherapists, and massage therapists treating localised muscle pain.
2. Dry Needling & Acupuncture
How it works:
Involves inserting fine needles directly into the trigger point to cause a local twitch response, reducing muscle tension and improving blood flow.
Acupuncture may help modulate pain pathways through neurochemical changes.
Scientific Basis:
Dry needling disrupts abnormal muscle contraction and releases neuropeptides like substance P, which contribute to pain.
📌 Best for: Chronic trigger points that do not respond to manual therapy.
Reference: Dommerholt et al. (2018), Current Pain and Headache Reports, showing efficacy in musculoskeletal pain.
3. Stretching & Post-Isometric Relaxation (PIR)
How it works:
Stretching lengthens shortened muscle fibres, reducing TrP activity.
PIR involves contracting the muscle gently before stretching to reset neuromuscular function.
Techniques:
Contract-Relax Stretching (PIR) – The patient performs a gentle isometric contraction for 5-10 seconds, followed by a slow stretch.
Passive and Active Stretching – Helps break the pain-spasm cycle and improve flexibility.
📌 Best for: Athletes and individuals with muscle tightness contributing to trigger points.
4. Heat & Cold Therapy
How it works:
Heat therapy (hot packs, warm baths) increases circulation, reducing muscle tension and promoting healing.
Cold therapy (ice packs, vapocoolant sprays) numbs pain and reduces inflammation.
Techniques:
Contrast Therapy: Alternating between hot and cold applications to enhance blood flow and reduce muscle spasm.
Spray and Stretch: A vapocoolant spray applied along the muscle before stretching.
📌 Best for: Acute flare-ups or when combined with stretching techniques.
5. Electrotherapy (TENS & Ultrasound)
How it works:
TENS (Transcutaneous Electrical Nerve Stimulation) blocks pain signals and increases endorphin release.
Therapeutic Ultrasound uses sound waves to promote tissue healing and reduce deep muscle tightness.
📌 Best for: Patients needing pain relief without hands-on intervention.
Reference: Kietrys et al. (2014), Journal of Manual & Manipulative Therapy, supports the use of ultrasound for TrP management.
6. Ergonomic & Postural Correction
How it works:
Identifying and correcting faulty postural habits that contribute to TrP formation.
Strengthening weak muscles and improving movement patterns.
Approaches:
Workstation Ergonomics – Adjusting desk height, chair position, and keyboard use.
Postural Training – Exercises like scapular retraction, core stability, and movement retraining.
📌 Best for: Office workers and individuals with postural dysfunction.
7. Pharmacological & Medical Interventions
How it works:
Pain-relieving medications (NSAIDs, muscle relaxants) help manage acute pain but do not treat the root cause.
Trigger Point Injections (TPI) involve local anaesthetic or corticosteroid injections to deactivate TrPs.
📌 Best for: Severe or persistent trigger points that do not respond to conservative treatments.
Reference: Fernández-de-las-Peñas et al. (2019), Pain Medicine, supports trigger point injections for chronic myofascial pain.
Final Thoughts on Treatment
A multimodal approach is often the most effective for treating trigger points. Combining manual therapy, stretching, and lifestyle modifications provides the best long-term results.
Conclusion
Trigger points are a significant contributor to myofascial pain syndromes, with complex neurophysiological mechanisms underlying their formation and maintenance. Ongoing research continues to elucidate these mechanisms, offering insights that may improve clinical management. A thorough understanding of TrP types and their neurophysiology is crucial for healthcare professionals, particularly manual therapists, in effectively addressing musculoskeletal pain and dysfunction.
