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[CLINICAL TECHNIQUES]

Identifying and Injecting Myofascial Trigger Points

Joseph J. Ruane, DO

William O. Roberts, MD
Department Editor

THE PHYSICIAN AND SPORTSMEDICINE - VOL 29 - NO. 12 - DECEMBER 2001


Myofascial pain syndrome is characterized by the presence of discreet, hypersensitive nodules known as trigger points. A myofascial trigger point is a hyperirritable locus within a taut band of skeletal muscle, located in the muscle and/or fascia (1). They are palpable within muscles as cord-like bands within a sharply circumscribed area of extreme tenderness. Trigger points are found most commonly in muscles involved in postural support.

Treatment options include use of nonsteroidal anti-inflammatory drugs (NSAIDs), therapeutic exercise, massage therapy, and spray and stretch techniques. Although NSAIDs have not been shown to be effective, some physicians suggest them to help ease postinjection soreness or to make patients more comfortable during exercise and return to daily activities. For recalcitrant cases, injection of an anesthetic into the points can help bring relief.

Identifying Active Trigger Points

Accurate identification of true, active trigger points is essential for satisfactory outcomes. Look for these clinical characteristics (1,2):

  • Within affected muscle, pain is increased by passive or active stretching, and range of motion is restricted;
  • Contracting the muscle against fixed resistance significantly increases pain;
  • Tenderness and dysesthesias are commonly referred in characteristic, well-defined zones;
  • Firm pressure applied over the point usually elicits a "jump sign," with the patient crying out, wincing, or withdrawing from the stimulus; and
  • One or several fasciculations, called the local twitch response, may be observed when firm pressure is applied over the point such as with the snapping technique of Simons et al (1).

Injection Technique

The patient should lie on an examination table in case of syncope or significant unexpected withdrawal motions. Use of a 22-gauge, 1.5-in. needle will usually suffice. Sensitive patients may better tolerate a 25-gauge needle; however, the smaller needle may not provide the tactile feedback necessary when penetrating the tissue and may not produce enough mechanical disruption to adequately inactivate the trigger point (2).

A 0.5% solution of procainamide hydrochloride (1 part of 2% procainamide with 3 parts of sterile normal saline) or 1% plain lidocaine are the agents of choice and provide the best results with the least tissue irritation. Dry needling can successfully deactivate trigger points, but it has a higher incidence of postinjection soreness (3). Needling with saline does not provide comparable relief, and injection with sterile water can be painful. Corticosteroids are not usually injected because they can induce tissue destruction and additional complications (1-3).

Disinfect the injection site. Roll the active point between your fingers (figure 1A) to appreciate any play in the subcutaneous tissue and allow accurate placement of the needle. Use downward pressure on either side of the nodule with the second and third digits (figure 1B) to immobilize the target, make the skin taut, and minimize pain.

Desensitize the skin with a spray of ethyl chloride or other vapocoolant before the injection. Hold the syringe tip like a dart with the fingertips and thrust quickly through the epidermis just as the spray evaporates. Pass the needle through the tissue with a slow, steady advancement toward the target. Contact with the trigger point feels as if the needle has entered a dense, gummy nodule, and sometimes a "pop" is felt. The patient may have a sudden increase in pain when the needle reaches its target and may also experience radiating pain along adjacent muscles and tendons.

Active trigger points will often yield a local twitch response when penetrated. This phenomenon verifies correct needle placement and also is thought to represent unit deactivation. Inject the anesthetic (0.5 to 1.0 mL) immediately after the twitch ceases. Multiple trigger points are often clustered, and all must be treated without withdrawing the needle (figure 2). Direct pressure after injections avoids irritation from bleeding.

Postinjection Care and Considerations

Many physicians believe that passive stretching after injection is indispensable, and that not doing so can diminish therapeutic effectiveness (1). Several resources describe spray and stretch techniques using vapocoolant to enhance tissue relaxation and restore range of motion (1,4). Hot packs applied for 10 to 15 minutes postinjection can decrease patients' soreness. Finally, over-the-counter analgesics and a home stretching program will enhance long-term results (2).

Missing an active trigger point core is a common cause of treatment failure. Another frequent error is injecting into a tender area or referred pain zone without finding the actual trigger point. Injecting into a tense, fibrous band that is not a true trigger point can irritate the surrounding tissue.

Addressing perpetuating factors is essential. Poor posture, muscle imbalances, exercise habits, work ergonomics, and psychosocial factors can all influence maintenance of pain. Duration of pain may also influence outcomes.

Pneumothorax is the most common serious injection complication. Others include vasovagal syncope, skin infection, toxic reactions to local anesthetic, hematoma, neuritis, and compartment syndrome. Review relevant anatomy before injecting, especially into the thoracic cage or cervical spine area.

References

  1. Simons DG, Travell JG, Simons LS: Travell & Simons' Myofascial Pain and Dysfunction: The Trigger Point Manual, ed 2. Baltimore, Williams and Wilkins, 1999, pp 22, 23, 150-164
  2. Esenyel M, Caglar N, Aldemir T: Treatment of myofascial pain. Am J Phys Med Rehabil 2000;79(1):48-52
  3. Hong CZ: Lidocaine injection versus dry needling to myofascial trigger point: the importance of the local twitch response. Am J Phys Med Rehabil 1994;73(4):256-263
  4. Fomby EW, Mellion MB: Identifying and treating myofascial pain syndrome. Phys Sportsmed 1997;25(2):67-75

Dr Ruane is Director of Musculoskeletal Health at the McConnell Heart Health Center in Columbus, Ohio, and team physician for the NHL Columbus Blue Jackets.


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