Trigger Point Injection

Aka: Trigger Point Injection, Trigger-Point Injection

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II. Indications

  1. Tension Headache (Occipital Headache)
    1. Trigger Point Injection at trapzius insertion
  2. Myofascial Pain Syndrome
    1. Symptomatic active Trigger Point AND
    2. Twitch response to pressure with referred pain

III. Contraindications

  1. Known Bleeding Disorder
  2. Anticoagulation (includes Aspirin in last 3 days)
  3. Local or systemic infection
  4. Acute Trauma at Muscle site
  5. Anesthetic allergy
  6. Suspicion for non-Myofascial Pain (e.g. malignancy)
  7. Unsafe injection site (e.g. underlying neurovascular structures)
    1. Example: Intercostal space (risk of Pneumothorax)

IV. Mechanism

  1. Mechanical disruption of Trigger Point
  2. Dry needle "poking" of Trigger Points is also effective
    1. However, may result in more post-injection soreness
  3. Injections are specifically for Trigger Points
    1. Trigger Points on compression result in referred pain
    2. Injections are not simply tender

V. Preparation

  1. Medications
    1. Bupivicaine (Sensorcaine) 0.25%: 5 cc total
      1. May be used alone (effective) or with Corticosteroid
    2. Triamcinolone (Kenalog) 40 mg/ml: 1 cc
      1. Some studies demonstrate no additional benefit with Corticosteroid versus Anesthetic alone
      2. Mechanism of Trigger Point Injection effect is likely more than antiinflammatory activity
        1. Myofascial Pain does not appear to be inflammatory
      3. In addition to lack of benefit, Corticosteroids have risks (Hyperglycemia, infection, skin atrophy)
    3. Normal Saline (or dy needling)
      1. Non-inferior to Lidocaine 1% with Triamcinolone injection
      2. Roldan (2020) Am J Emerg Med 38(2): 311-6 [PubMed]
  2. Needle selection
    1. Select needle of adequate length
      1. Prevents burying needle to hub (risk or breakage)
    2. Select needle of adequate gauge
      1. Allows for necessary mechanical disruption
      2. Less likely to be deflected from taut Muscle
    3. Needle examples
      1. Shallow sites
        1. Optimal: 25-27 gauge 1.25 to 1.5 inch needle
        2. Alternative: Tuberculin syringe (5/8 inch)
      2. Deeper sites or obese patient
        1. Spinal needle (21 gauge 2.5 inch needle)

VI. Technique

  1. Position patient comfortably
  2. Patient identifies one to four Trigger Points (painful regions)
    1. See Trigger Point Location
    2. Mark the most Tender Points on palpation (1-2 cm regions of spasm) with a surgical pen
    3. Most common Trigger Points for injection are trapezius, levator Scapulae and neck Muscles
  3. Consider performing under Ultrasound guidance when in the region of important structures (e.g. neurovascular, lung)
  4. Anticipate initial increased pain on injection
    1. Local twitch and referred pain confirms placement
    2. Injecting near Trigger Point may cause irritation
  5. Start with most tender spot in Trigger Point (identified via palpation)
    1. Localize most tender spot within taut Muscle-fibers
    2. Fix tender spot between fingers (1-2 cm in size)
      1. Prevents from rolling away from needle
      2. Controls subcutaneous bleeding
  6. Cleanse overlying skin
    1. Use Alcohol swab, Betadine or Hibiclens
  7. Inject Trigger Point
    1. Select needle as above
    2. Warn patient of possible pain on injection (associated with pH of medication, tissue expansion)
      1. Slowly injecting may reduce pain
    3. Direct needle at 30 degree angle off skin
      1. Insert needle into skin 1-2 cm from Trigger Point
      2. Advance needle into Trigger Point
    4. Use 1-2 ml Anesthetic total at each Trigger Point
    5. Use a fanning technique of injection (0.3 to 0.5 ml at a time)
      1. Repeat until local twitch or tautness resolves
      2. Cycles of redirecting needle and reinjecting
        1. Withdraw needle to subcutaneous tissue
        2. Redirect needle into adjacent tender areas
  8. Hold direct pressure at injection site for 1-2 minutes
    1. Prevents Hematoma formation
    2. Helps distribute Anesthetic
  9. Repeat procedure for other Tender Points
  10. Patient gently stretches injected areas
    1. Full active range of motion in all directions
    2. Repeat range of motion three times after injection

VII. Management: Post-Procedure Instructions (Reduce postinjection flare)

  1. Patient avoids over-using injected area for 3-4 days
    1. Maintain active range of motion of injected Muscle
  2. Patient applies ice to injected areas for a few hours
  3. Anticipate post-injection soreness for 3-4 days

VIII. Complications

  1. Local Skin Infection at injection site
  2. Local Hematoma at injection site
  3. Pneumothorax
  4. Medication Hypersensitivity
  5. Peripheral Nerve Injury

IX. Course

  1. Expect 2-4 months of benefit after injection

X. Precautions

  1. Avoid repeat injection if unsuccessful on 2-3 attempts
  2. Re-evaluate for possible repeat injection after 4 days

XI. References

  1. Ruoff in Pfenninger (1994) Procedures, Mosby, p. 164-7
  2. Sola in Roberts (1998) Procedures, Saunders, p. 890-901
  3. Strayer in Herbert (2016) EM:Rap 16(11): 1-2
  4. Warrington (2020) Crit Dec Emerg Med 34(9): 14
  5. Alvarez (2002) Am Fam Physician 65(4):653-60 [PubMed]
  6. Fomby (1997) Phys Sportsmed 25(2):67-75 [PubMed]
  7. Shipton (2023) Am Fam Physician 107(2): 159-64 [PubMed]

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