Trigger Point Injection

1. Indication: Myofascial Pain Syndrome
   1. Symptomatic active Trigger Point and
   2. Twitch response to pressure with referred pain
2. 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. Unsafe injection site
      1. Example: Intercostal space (risk of Pneumothorax)
3. 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
4. Technique
   1. Position patient comfortably
   2. Patient identifies one to four Trigger Points
   3. Anticipate initial increased pain on injection
      1. Local twitch and referred pain confirms placement
      2. Injecting near Trigger Point may cause irritation
   4. Start with most tender spot in Trigger Point
      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
   5. Cleanse overlying skin with Alcohol swab
   6. Anesthetic selection
      1. Procaine 0.5%
         1. Mix 2% Procaine with 3 parts saline
      2. Lidocaine 1% (Xylocaine 1%)
      3. Corticosteroid adds no additional benefit
   7. 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: 22 gauge 1.5 inch needle
            2. Alternative: Tuberculin syringe (5/8 inch)
            3. Narrow gauge: 27 gauge 1.5 inch needle
         2. Deeper sites or obese patient
            1. Spinal needle (21 gauge 2.5 inch needle)
   8. Inject Trigger Point
      1. Select needle as above
      2. Warn patient of possible pain on injection
      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 0.3 to 0.5 cc anesthetic at each Trigger Point
      5. Redirect needle and reinject
         1. Withdraw needle to subcutaneous tissue
         2. Redirect needle into adjacent tender areas
         3. Repeat until local twitch or tautness resolves
   9. Hold direct pressure at injection site for 2 minutes
      1. Prevents hematoma formation
   10. Repeat procedure for other Tender Points
   11. Patient gently stretches injected areas
       1. Full active range of motion in all directions
       2. Repeat range of motion three times after injection
5. 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
6. Complications
   1. Local Skin Infection at injection site
   2. Local hematoma at injection site
7. Course
   1. Expect 2-4 months of benefit after injection
8. Precautions
   1. Avoid repeat injection if unsuccessful on 2-3 attempts
   2. Re-evaluate for possible repeat injection after 4 days
9. References
   1. Ruoff in Pfenninger (1994) Procedures, Mosby, p. 164-7
   2. Sola in Roberts (1998) Procedures, Saunders, p. 890-901
   3. Alvarez (2002) Am Fam Physician 65(4):653-60
   4. Fomby (1997) Phys Sportsmed 25(2):67-75