Trigger point injection of local anaesthetic

• An introduction to trigger point injection of local anaesthetic
• What are trigger points?
• Clinical presentation of trigger points
• Management of trigger point pain
• Trigger point injection of local anaesthetic
• Are there any risks of trigger point injections?
• What should be expected after a trigger point injection?

An introduction to trigger point injection of local anaesthetic

Myofascial pain syndrome is associated with trigger points, which are discrete spots that are painful on compression and produce referred pain and tenderness as well as muscle dysfunction. One effective treatment for trigger point pain is trigger point injection of local anaesthetic.

What are trigger points?

Trigger points, as illustrated above, are discrete, focal, hyperirritable spots that are painful on compression and can produce referred pain or tenderness as well as problems with muscle function. Trigger points are seen in myofascial pain syndrome, a common painful muscle disorder.

Clinical presentation of trigger points

Patients often report regional persistent pain resulting in decreased range of movement of the muscle in question, which are often muscles involved in maintaining posture. In the head and neck region, trigger point pain may manifest as tension headache, tinnitus, temporomandibular joint pain, eye symptoms or torticollis. In the arm, the pain may mimic bursitis or tendonitis, and in the legs the pain can be a cause of limited range of movement of the knee or ankle.

Management of trigger point pain

Approaches to treatment of trigger point pain include:
Non-pharmacological:

• Trigger point injections of local anaesthetic.
• Other supportive measures, including acupuncture, massage, heat (see article on Analgesia).

The long-term effectiveness of various therapies has not been proven in clinical studies.
Pharmacological:

• Simple analgesia including paracetamol and NSAIDs
• Muscle relaxants
• Antidepressant medication as coanalgesia

Trigger point injection of local anaesthetic

Trigger point injection can effectively inactivate trigger points and provide prompt symptomatic relief.

Who should have a trigger point injection?

Patients with myofascial pain syndrome who have symptomatic trigger points.

Who should not have a trigger point injection?

If you have:

• Anticoagulation or bleeding disorders
• Aspirin ingestion within three days of injection
• The presence of local or systemic infection
• Allergy to anesthetic agents
• Acute muscle trauma
• Extreme fear of needles

Are there any risks of trigger point injections?

• Vasovagal syncope (fainting)
• Skin infection
• Collapsed lung (very rare)
• Haematoma formation; avoid by applying direct pressure for at least two minutes after injection.

What should be expected after a trigger point injection?

• Post-injection soreness is to be expected in most cases. This should not be confused with failure of treatment. This soreness usually lasts 3 to 4 days.
• You should remain active following the trigger point injections but avoid strenuous activity for the first 3 to 4 days after the injection.

References

1. Alvarez, D. Rockwell, P. Trigger points: diagnosis and management. Am Fam Physician. 2002; 65: 653-60.
2. Han, S. Harrison, P. Myofascial pain syndrome and trigger point management. Reg Anesth. 1997; 22: 89-101.
3. Imamura, S. Fischer, A. Imamura, M. et al. Pain management using myofascial approach when other treatment failed. Phys Med Rehabil Clin North Am. 1997; 8: 179-96.