TPI Medication Comparison - Ketorolac, Lidocaine, or Dexamethasone

Background

Trigger point injections (TPIs) are a commonly-performed procedures by physicians for the
treatment of myofascial pain, specifically targeting myofascial trigger points (MTrPs).
Commonly injected substances include local anesthetic, botulinum toxin, or corticosteroid
(CS), though non-steroidal anti-inflammatory drugs (NSAIDs) and other substances have been
reported. A Cochrane review found that intramuscular injection of local anesthetic
demonstrated moderate evidence of benefit for mechanical neck disorders; no other treatment
demonstrated greater benefit.

Great variation is seen in how TPIs are performed, however. The standard method was described
by Simons and Travell, and is often cited. Hong et al. demonstrated that, similar to the
technique described by Simons and Travell, obtaining a local twitch response (LTR) was the
most important factor in producing pain relief. Further research by Shah et al., which
demonstrated an inflammatory component to MTrPs, also showed a decrease in inflammatory
cytokines following trigger point injections that obtained a LTR. Despite these findings,
most studies do not use the LTR method in their TPI techniques.

Prior studies demonstrated that most patients obtain significant relief from TPI, but did not
identify differences between injection of CS or other substances. However, none of these
studies identified LTRs in their injection techniques.

As can be learned from a review of the published literature on muscular trigger points, the
cause of this condition is unknown, and no single treatment approach has been established as
a clearly accepted gold standard treatment. There is evidence, however, that there is an
inflammatory component associated with trigger points and that obtaining a local twitch
response is associated with a decrease in local inflammation at the site of a trigger point.
The combination of injecting an anti-inflammatory medication and obtaining a local twitch
response has never been studied. The purpose of this study is to examine the comparative
effectiveness of injectable substances on patient outcome after a TPI with LTR identified,
namely a CS (dexamethasone), a NSAID (ketorolac), or only a local anesthetic (lidocaine).

Inclusion Criteria:

1. Men or women age 18 or over

2. At least one active trigger point

Exclusion Criteria:

1. Allergy or contraindication to any NSAID, CS, or local anesthetic

2. Receiving anticoagulant medication

3. History of bleeding disorder

4. Pregnant or breast feeding women

5. Gastrointestinal ulceration

6. Pre-existing renal disease

7. Pre-existing congestive heart failure

8. Diabetes mellitus

9. Prior myocardial infarction or stroke

10. Fibromyalgia