Chapter 52

INDICATIONS

• Trigger point injections (TIs) are commonly used as a treatment option in patients with acute and chronic muscle pains associated with an irritable, tight or taut muscle band, or palpable knot within a muscle that can radiate pain into specific distant or referred pattern called the “reference pain zone.”

• Pain can be present at rest, with poor posture or with overuse activity increasing the stress of a particular muscle or muscles involved. It can be the primary pathology in a muscle injury due to trauma or accident (ie, Whiplash) or secondary to underlying problem such as disk herniations, facet joint pain or bone, nerve injury.

• Trigger points are commonly present in patients with myofascial pain syndrome. This is a chronic regional localized pain syndrome with several trigger points limited to a particular area of the body. The neck and upper and lower back are commonly involved areas.

• In the cervical and thoracic area common muscles involved include the paraspinal muscles: splenius capitis, sternocleidomastoid, trapezius, levator scapulae, rhomboids, latissimus dorsi, serratus posterior inferior.

• In the lumbar spine, it commonly involves the quadratus lumborum (both deep and superficial), psoas, internal oblique, iliocostalis, longissimus or deep semispinalis, and multifidus.

• Trigger points in the shoulder rotator cuff muscles (supraspinatus, infraspinatus, subscapularis, and teres minor) and shoulder blade area such as serratus posterior superior, latissimus dorsi, teres major, coracobrachialis, serratus anterior can present with referred pain patterns that can mimic or be confused with nerve root or radicular distribution.

• Similarly, trigger points in the gluteus medius, minimus, and piriformis muscles can refer down the posterior lateral thigh and be confused with sciatica.

• Trigger points are not to be confused with tender points commonly present in patients with fibromyalgia in which pressure in the tender points cause pain but no distant reference zone.

PHYSICAL EXAMINATION

• Physical examination findings include a knot, tight or taut muscle band.

• Associated with muscle spasm, irritable muscle with positive “jump sign,” histamine reaction.

• Painful on resistance to movement as during manual muscle strength testing.

• Referred pain in a “reference pain zone.”

• And at times, muscle twitch presents with pressure or when needle is inserted in the muscle.

• A pressure algometer can be use to quantify abnormal pressure pain sensitivity over trigger points and to identify the most painful trigger points for injection.

• Increase of pressure pain threshold by 2 to 3 kg immediately after TPI indicates that the injection was effective.

• A trigger point is called active when the referred pain is present spontaneously and latent when the referred pain is elicit with pressure or muscle activity.

TYPICAL REFERRED PATTERNS

Goal of Trigger Point Injections

The primary goal of the trigger point injections is to inactivate the trigger points by destroying and anesthetizing the primary area of pain through needling and infiltration with injectable solution.

Equipment and Supplies

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