Myofascial Pain in Athletes Medication

Updated: Oct 07, 2015
  • Author: Auri Bruno-Petrina, MD, PhD; Chief Editor: Sherwin SW Ho, MD  more...
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Medication

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. [21]

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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.

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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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