Medication Summary
Anti-inflammatory agents, including corticosteroids and analgesics, are generally not useful, and their administration should be avoided. Localized and regional muscle pain syndromes often respond to specific localized therapies. The most common treatment for localized muscle pain is injection. Take great care in locating the TrP, watch for the twitch response on the muscle, and then enter the muscle with the needle. [28]
Local anesthetics
Class Summary
Amide derivative local anesthetic used to minimize postinjection soreness.
Lidocaine HCL (Xylocaine)
Has rapid onset of action. Stabilizes neuronal membrane by inhibiting the sodium flux required for the initiation and conduction of impulses. In addition, causes inhibition of release of neurotransmitters (eg, substance P), ATP from nociceptive afferent C fibers, modulation in information transfer along primary afferents, and central sympathetic blockade with decrease in pain-induced reflex vasoconstriction.
Procaine (Novocaine)
Regional anesthesia for treatment of painful conditions (eg, neuropathic pain, reflex sympathetic dystrophy, myofascial pain). Least myotonic and has lowest systemic toxicity among commonly used local anesthetics. Procaine is the ester of p-aminobenzoic acid and ethanol with a tertiary diethylamino group attached at the other end of the alcohol. Stabilizes neuronal membrane and prevents the initiation and transmission of impulses. Has a rapid onset of action and relatively short duration depending on anesthetic technique, type of block, concentration, and patient. Greater solution concentration does not increase anesthetic effect.
Neurotoxin
Class Summary
Botulinum toxin type A (BTA) binds irreversibly to presynaptic cholinergic nerve terminals, which includes the terminals of motor nerve supplying skeletal muscle-fiber endplates. Since the primary dysfunction of motor endplates associated with the TrP phenomenon appears to be excessive release of acetylcholine (ACh), injections into the TrP of a substance (eg, BTA) that only blocks ACh should be specific TrP therapy. This toxin specifically acts only on the neuromuscular junction, effectively denervating that muscle cell.
OnabotulinumtoxinA (BOTOX®)
BTA blocks neuromuscular transmission through a 3-step process, as follows: (1) blockade of neuromuscular transmission; BTA binds to the motor nerve terminal. The binding domain of the type A molecule appears to be the heavy chain, which is selective for cholinergic nerve terminals. (2) BTA is internalized via receptor-mediated endocytosis, a process in which the plasma membrane of the nerve cell invaginates around the toxin-receptor complex, forming a toxin-containing vesicle inside the nerve terminal. After internalization, the light chain of the toxin molecule, which has been demonstrated to contain the transmission-blocking domain, is released into the cytoplasm of the nerve terminal. (3) BTA blocks acetylcholine release by cleaving SNAP-25, a cytoplasmic protein that is located on the cell membrane and that is required for the release of this transmitter. The affected terminals are inhibited from stimulating muscle contraction. The toxin does not affect the synthesis or storage of acetylcholine or the conduction of electrical signals along the nerve fiber.
Typically, a 24-72 h delay between administration of toxin and onset of clinical effects exists, which terminate in 2-6 mo.
This purified neurotoxin complex is a vacuum-dried form of purified BTA, which contains 5 ng of neurotoxin complex protein per 100 U.
BTA has to be reconstituted with 2 mL of 0.9% sodium chloride diluent. With this solution each 0.1 mL results in 5 U dose. Patient should receive 5-10 injections per visit.
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Myofascial pain in athletes. Schematic of a trigger point complex of a muscle in longitudinal section.A: The central trigger point (CTrP) in the endplate zone contains numerous electrically active loci and numerous contraction knots. A taut band of muscle fibers extends from the trigger point to the attachment at each end of the involved fibers. The sustained tension that the taut band exerts on the attachment tissues can induce a localized enthesopathy that is identified as an attachment trigger point (ATrP).B: Enlarged view of part of the CTrP shows the distribution of 5 contraction knots. The vertical lines in each muscle fiber identify the relative spacing of its striations. The space between 2 striations corresponds to the length of one sarcomere. The sarcomeres within one of these enlarged segments (ie, contraction knot) of a muscle fiber are markedly shorter and wider than the sarcomeres in the neighboring normal muscle fibers, which are free of contraction knots.
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Myofascial pain in athletes. Cross-sectional drawing shows flat palpation of a taut band and its trigger point.Left: Skin pushed to one side to begin palpation (A). The fingertip slides across muscle fibers to feel the cord-line texture of the taut band rolling beneath it (B). The skin is pushed to other side at completion of movement. This same movement performed vigorously is snapping palpation (C).Right: Muscle fibers surrounded by the thumb and fingers in a pincer grip (A). The hardness of the taut band is felt clearly as it is rolled between the digits (B). The palpable edge of the taut band is sharply defined as it escapes from between the fingertips, often with a local twitch response (C).
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Myofascial pain in athletes. Longitudinal schematic drawing of taut bands, myofascial trigger points, and a local twitch response. A: Palpation of a taut band (straight lines) among normally slack, relaxed muscle fibers (wavy lines). B: Rolling the band quickly under the fingertip (snapping palpation) at the trigger point often produces a local twitch response that usually is seen most clearly as skin movement between the trigger point and the attachment of the muscle fibers.
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Myofascial pain in athletes. Sequence of steps to use when stretching and spraying any muscle for myofascial trigger points.
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Myofascial pain in athletes. Schematic drawing showing how the jet stream of Vapo coolant is applied.
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Myofascial pain in athletes. Cross-sectional schematic drawing shows flat palpation to localize and hold the trigger point for injection. A and B show use of alternate pressure between 2 fingers to confirm the location of the palpable module of the trigger point. C shows positioning the trigger point half way between the fingertips to keep it from sliding to one side during the injection.
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Myofascial pain in athletes. Schematic top view of 2 approaches to the flat injection of a trigger point area in a palpable taut band. Injection away from the fingers (A) and injection toward the fingers (B).
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Myofascial pain in athletes. C. Z. Hong's technique. Finger pressure beside the needle is used to indent the skin, subcutaneous, and fat tissues so that the needle can reach the trigger point in a muscle that would be inaccessible otherwise.
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Myofascial pain in athletes. Diagrammatic representation of pre-injection sites (open circles) and injection sites (solid circles) of local anesthetic to the trigger point. The enclosed stippled area represents the taut band. This diagram distinguishes the central trigger point within the large broken circle from the attachment trigger points located at the myotendinous junction and at the attachment of the tendon to the bone. Each of these 3 trigger point regions can be identified by their individual spot tenderness and anatomical locations. No rationale is apparent for injecting the part of the taut band that lies between the central trigger point and the attachment trigger point (solid circles numbers 7-10).
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Myofascial pain in athletes. Mechanism of botulinum toxin type A.
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Myofascial pain in athletes. Binding of neuromuscular transmission with botulinum toxin type A, which binds the motor nerve terminal.
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Myofascial pain in athletes. After botulinum toxin type A is internalized, the light chain of the toxin molecule is released into the cytoplasm of the nerve terminal.
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Myofascial pain in athletes. Botulinum toxin type A blocks acetylcholine by cleaving a cytoplasmic protein on the cell membrane.
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Myofascial pain in athletes. After the botulinum toxin type A exerts its clinical toxic effect, a nerve sprout eventually establishes a new neuromuscular junction, and muscle activity gradually returns. However, new research findings suggest that this new nerve sprout retracts and the original junction returns to functionality.
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Myofascial pain in athletes. After the clinical toxic effect of botulinum toxin type A occurs, axon sprouting and muscle fiber reinnervation terminate the clinical effect of the toxin, which results in the reestablishment of neuromuscular transmission.
Tables
Region |
Practice |
Number Studied |
Prevalence of Myofascial Pain, % |
General |
Medical |
172 |
30 |
General |
Pain medical center |
96 |
93 |
General |
Comprehensive pain center |
283 |
85 |
Craniofacial |
Head and neck pain clinic |
164 |
55 |
Lumbogluteal |
Orthopedic clinic |
97 |
21 |
Initial Diagnosis |
TrPs |
Angina pectoris, atypical |
Pectoralis major |
Appendicitis |
Lower rectus abdominis |
Atypical facial neuralgia |
Masseter, temporalis, sternal division of the sternocleidomastoid, upper trapezius |
Atypical migraine |
Sternocleidomastoid, temporalis, posterior cervical |
Back pain, middle |
Upper rectus abdominis, thoracic paraspinals |
Back pain, low |
Lower rectus abdominis, thoracolumbar paraspinals |
Bicipital tendinitis |
Long head of the biceps brachii |
Chronic abdominal wall pain |
Abdominal muscles |
Dysmenorrhea |
Lower rectus abdominis |
Earache, enigmatic |
Deep masseter |
Epicondylitis |
Wrist extensors, supinator, triceps brachii |
Frozen shoulder |
Subscapularis |
Myofascial pain dysfunction |
Masticatory muscles |
Occipital headache |
Posterior cervicals |
Post-therapeutic neuralgia |
Serratus anterior, intercostals |
Radiculopathy, C6 |
Pectoralis minor, scalenes |
Scapulocostal syndrome |
Scalenes, middle trapezius, levator scapulae |
Subacromial bursitis |
Middle deltoid |
Temporomandibular joint disorder |
Masseter, lateral pterygoid |
Tennis elbow |
Finger extensors, supinator |
Tension headache |
Sternocleidomastoid, masticatory, posterior cervicals, suboccipital, upper trapezius |
Thoracic outlet syndrome |
Scalenes, subscapularis, pectoralis minor and major, latissimus dorsi, teres major |
Feature |
Myofascial Pain (TrPs) |
Fibromyalgia |
Female-to-male ratio |
1:1 |
4-9:1 |
Pain |
Local or regional |
Widespread, general |
Tenderness |
Focal |
Widespread |
Muscle |
Feels tense (taut bands) |
Feels soft and doughy |
Motion |
Restricted range of motion |
Hypermobility |
Examination |
Examine for TrPs |
Examine for tender points |
