Trigger point causes treatment and dry needling technique

 Myofascial trigger points are the most common complaint of most of the adults and teens as well which causes pain with a referral pattern. In this article we will discuss about the myofascial trigger points, myofascial trigger points releasing techniques, dry needling technique and etiology of trigger points.



MYOFASCIAL TRIGGER POINTS

Simons, Travell, and Simons defined the myofascial trigger point (MTrP) as a hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band. The spot is tender when pressed, and can give rise to characteristic referred pain, motor dysfunction, and autonomic phenomena . "

 

Thus, each MTrP contains a sensory component, a motor component, and an autonomic component. These components comprise a new "integrated hypothesis" regarding the etiology of MTrPs.l This hypothesis involves local myofascial tissues, the central nervous system (CNS), and systemic biomechanical factors. The "integrated hypothesis" has changed our approach to treating MTrPs..

 


TRIGGER POINT DRY NEEDLING AND 
ACUPUNCTURE NEEDLE

Trigger point dry needling (TrP-DN), also referred to as intramuscular stimulation (lMS), is an invasive procedure in which an acupuncture needle is inserted into the skin and muscle. As the name implies, TrP-DN is directed at myofascial trigger points (MTrPs), which are defined as "hyperirritable spots in skeletal muscle that are associated with a hypersensitive palpable nodule in a taut band."l Physical therapists around the world practice TrP-DN as part of their clinical practice and use the technique in combination with other physical therapy interventions. TrP-DN falls within the scope of physical therapy practice in many countries, including Canada, Chile, Ireland, The Netherlands, South Africa, Spain, and the United Kingdom.

 

               

DRY NEEDLING TECHNIQUES

 Because dry needling techniques emerged empirically, different schools and conceptual models have been developed, including the radiculopathy model, the MTrP model, and the spinal segmental sensitization model approaches, such as neural acupuncture and automated or electrical twitch-obtaining intramuscular stimulation with lidocaine for the treatment of myofascial pain. Jennifer Chu, developed electrical twitch-obtaining intramuscular stimulation; this approach combines aspects of the radiculopathy model with the trigger point model.

Another classification is based on the depth of the needle insertion and distinguishes superficial dry needling (SDN) and deep dry needling (DDN). Examples of SDN include Baldry's SDN approach and Fu's subcutaneous needling, which fall within the trigger point (TrP) modeI. The needling approach advocated by the radiculopathy model is a form of DDN. The TrP model includes both superficial dry needling (TrPSDN) and deep dry needling (TrP-DDN)

 


TRIGGER POINT MODEL

Clinicians practicing from the perspective of the trigger point model specifically target MTrPs. The clinical manifestation of MTrPs is referred to as MPS and is defined as the "sensory, motor, and autonomic symptoms caused by MTrPs."Myofascial trigger points may consist of multiple contraction knots, which are thought to be due to an excessive release of acetylcholine (ACh) from select motor endplates, and can be divided into active and latent MTrPs. The release of ACh has been associated with endplate noise, a characteristic electromyographic discharge at MTrP sites, consisting of low-amplitude discharges in the order of 10-50 JIV and intermittent high-amplitude discharges (up to 500 JlV) in painful MTrPs. Active MTrPs can spontaneously trigger local pain in the vicinity of the MTrP, or they can refer pain or paresthesiae to more distant locations. They cause muscle weakness, range of motion restrictions, and several autonomic phenomena. Latent MTrPs do not trigger local or referred pain without being stimulated, but they may alter muscle activation patterns and contribute to limited range of motion.Simons, Travell, and Simons documented the referred pain patterns of MTrPs in 147 muscles,! while Dejung published slightly different referred pain patterns based on their empirical findings. Several case reports and research studies have examined referred pain patterns from MTrPs


LOCAL TWITCH RESPONSE

One of the unique features of MTrPs is the phenomenon of the so-called local twitch response (LTR), which is an involuntary spinal cord reflex contraction of the muscle fibers in a taut band following palpation or needling of the band or MTrp. Local twitch responses can be elicited manually by snapping taut bands that harbor MTrPs. When using invasive procedures like TrP-DDN or injections therapeutically, eliciting LTRs is essential. Not only is the treatment outcome much improved, but LTRs also confirm that the needle was indeed placed into a taut band, which is particularly important when needling MTrPs close to peripheral nerves or viscera, such as the lungs.

 

 


ETIOLOGY OF MYOFACIAL TRIGGER POINTS

Cause of the Taut Band

The cause of trigger points is a matter of speculation. It appears evident from  clinical inspection that a trigger point forms as a latent trigger point first and then becomes tender or not depending on the degree of activation. This sequence of events is assumed because latent trigger points exist without spontaneous pain. Pain is induced in muscle trigger points with physical activity. Trigger point tenderness does not occur except in regions of muscle hardness, but regions of muscle hardness occur without local or referred pain. It is concluded that muscle hardness or the taut band that occurs in the absence of pain is the first abnormality, and that the active trigger point is a more developed or secondary stage of the trigger point. However, this sequence of events, as simple as it is, has not been systematically studied and confirmed.

 


ROLE OF NEUROMUSCULAR JUNCTION IN

 TRIGGER POINT FORMATION

Trigger point pain does not occur in the absence of a taut band, as stated above. The mechanism of local and referred pain is well understood as a general phenomenon, based on the release of local neurotransmitters, hydrogen ions, potassium ions and cytokines peripherally, and the activation of nociceptive neurons in the dorsal horn centrally. The spread of nociceptive neuronal activation segmentally is also a well-described phenomenon, regardless of the tissue of pain origin. However, the underlying, initial change in muscle associated with the trigger point seems to be a motor phenomenon, the development of the taut band. How the taut band develops remains a matter of speculation and has not been proven.

 

PERIPHERAL NERVE ALTERATIONS IN

 MYOFASCIAL PAIN SYNDROME

Peripheral nerve sensitization is well recognized in chronic pain syndromes. It has not been addressed in myofascial pain syndromes, where emphasis has been placed more on changes in muscle than in nerve. Nevertheless, it would seem reasonable that peripheral nerve sensitization would be a consequence of chronic myofascial pain Just as it would in other chronic pain syndromes. Some manifestations of the myofascial trigger point are clearly related to a spinal reflex, such as the local twitch reflex. Further studies have suggested that there is a central integration at the spinal cord level in animal trigger point models.  The role of the peripheral nerve at the neuromuscular junction and its relationship to anterior horn cell function, however, have been little studied. A study of neuromuscular jitter by stimulated single fiber electromyography showed a significantly increased mean consecutive difference in the trapezius and levator scapulae muscles in subjects with myofascial pain syndrome compared to controls. This study demonstrated instability of peripheral late function that could be related to

(1)   peripheral motor nerve axonal degeneration and regeneration, or (2) motor neuron degeneration with development of collateral reinnervation. The implication is that the myofascial trigger point is a complex dysfunction with peripheral and/or central motor dysfunction as well as a sensory abnormality with peripheral and/or central hypersensitization.

 

 


MUSCLE STRESS AND OVERUSE

 The general proposition is widely accepted that muscle overuse or biomechanical stress is the cause of the trigger point, resulting in the dysfunctional neuromuscular junction. This concept is central to Simons' integrated hypothesis of the trigger point and is expressed by Simons all as an energy crisis that they think is the primary cause of trigger point phenomena. Many studies show that supramaximal muscle contraction or overloaded eccentric contraction can damage muscle and lead to pain, including delayed-onset muscle soreness. Repetitive strain is considered a variant of muscle overload and is thought to have the same effect. Maintenance of fixed positions for long periods of time and sustained contraction of muscle as a result of emotional stress (anxiety, fear, depression) are also thought to produce muscle overuse.

WEAKNESS

Muscles harboring a trigger point are often weak) without atrophy.The weakness is usually rapidly reversible immediately on inactivation of the trigger point. One postulated mechanism is the limiting of muscle contraction below the threshold that activates painful triggers. However, inhibition of effort or contractile force in one muscle is known  to be the result of a trigger point in a different muscle, indicating some type of central inhibition of muscle activity.

 

HYPOXIA AND ISCHEMIA

 The myofascial trigger zone or region is thought to be hypoxic, consistent with the concept that there is capillary compression and ischemia. Ischemia and hypoxia, in this construct, are inevitably connected. One study of tissue oxygen tension recorded temperatures in tender, tense indurations. There was a region of severe oxygen desaturation at the presumed core of induration, surrounded by a region of increased oxygenation, as if the core were ischemic and surrounded by a hyperemic zone.

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