Muscle pain associated with passive acu-reflex points can be caused by a wide array of clinical conditions. Inflammatory diseases of muscle are the most common cause of muscle pain, and inherited myopathies are another possible source of muscle symptoms. In addition, nonpathophysi-ologic behavioral conditions such as stressful posture and repetitive overuse of muscles can cause myopathies.
Some possible conditions are briefly reviewed for consideration in dealing with clinical cases. This review demonstrates the complicated origins of muscle pain and how multidisciplinary approaches are required for many patients.
The causes of muscle pain and the appearance of passive acu-reflex points may be mechanical, pathologic (caused by chronic diseases), or iatrogenic (caused by drugs). Mechanical causes of muscle pain can be subdivided into ergonomic, structural, and postural pain syndromes. Ergonomic stress includes unfamiliar eccentric exercise, excessive exercise, and repetitive exercise syndromes. These are the primary causes of muscle pain for most athletes. Some of the most common mechanical stresses are discussed as follows.
Delayed-onset muscle soreness (DOMS) occurs after eccentric exercise and also after exercise of an ischemic muscle.1 Exercise under these conditions causes injury to the muscle fiber and consequent muscle soreness. Natural healing may take 3 weeks to complete. Muscle fiber destruction after maximally eccentric contraction happens in a similar way as the changes that are seen in exercised isch-emic muscle.2-4 Untrained eccentric exercise also produces immediate damage to muscle and delayed muscle soreness in the days afterwards. Muscle soreness is the result of local muscle damage, inflammation, and nociceptor sensitization.5 Repetitive exercise may entail repeated eccentric or lengthening contractions. Keyboard entry, for example, has been the cause of forearm pain and lateral epicon-dylalgia. The injury in lateral epicondylalgia occurs during the "down-stroke," or lengthening, phase of movement. When making a keyboard stroke, the finger is flexed while the wrist remains held in an extended position, in such a way that the extensor digitorum is lengthened while contracted.
Hypermobility syndromes also cause passive acu-reflex points and muscle pain. These syndromes produce multiple mechanical stresses. When ligaments are too slack to maintain joint stability, muscles are then recruited to keep up joint integrity; this results in structural stress. The mechanism of injury appears to be the muscular stress or overload that arises from the effort necessary to maintain integrity of the joint.
A head-forward posture is a common cause of pain in the neck, shoulder, facial joints, and back. It places stress on the extensor muscles of the neck and shoulder (longissimus cervicis, semispinalis capi-tis, semispinalis cervicis, splenius capitis, splenius cervicis, the suboccipital muscles at the base of the skull, and the trapezius and levator scapulae muscles). This posture is often associated with posterior displacement of the mandible and temporomandibular joint pain. Myalgic syndromes of the posterior cervical muscle and shoulder muscle are thus frequently associated with head pain and headache. Myalgic headache is often the result of postural or ergonomic stress on the shoulder and neck muscles.6
Pelvic torsion-related pain is associated with leg-muscle shortening or leg length pseudo-inequality and may possibly be related to lumbar and pelvic floor myopathy. In pelvic torsion, rotation of the pelvic iliac bone causes an ipsilateral high positioning of the posterior superior iliac spine and a low positioning of the anterosuperior iliac spine, which results in inequality of leg length. Scoliosis that results from pelvic torsion produces an asymmetry in shoulder height and mechanical stress on neck and shoulders, which can cause myalgic headache, neck pain, and shoulder pain.7-11
Sacroiliac joint dysfunction, or sacroiliac joint hypomobility, is another common problem in many athletes. It can cause pelvic and spine dysfunction that results in widespread axial muscle pain. Pain may be felt in the sacroiliac joint region of either the hypomobile side or the normal side and can be referred to the low back, the shoulders and neck, and the legs.
Somatic dysfunction, or muscle-joint dysfunction, is a limitation of range of motion caused by muscular restriction of joint motion. These restrictions can be painful and are often associated with palpable passive acu-reflex points.
Static overload occurs when mechanically stressful positions are held for prolonged periods of time. The active muscles gradually become fatigued. A fixed posture held for a long time causes pain in postural muscles. Another postural problem that is common in daily life is the eye-hand dominance habit: The head is rotated to bring the dominant eye closer to reading material that is on the contralateral hand-dominant side. Another example is back pain that is often related to the habit of carrying a child on one hip, often seen in mothers.
Nerve root compression produces acute or chronic myofascial pain, causing sensitized trigger points, muscle tension or spasms, and muscle deficiency. Passive acu-reflex points can develop acutely when an acute disc herniation occurs, and this can precede any neurologic disorder such as weakness, paresthesia, sensory loss, or inhibition of reflex. Such neurologic disorder always occurs within days of the onset of muscle pain. Needling can relieve the pain, but it may be for only days or hours. In such cases, the patient should be referred to a neurologist while the needling treatment continues.
Muscle imbalance is also a common cause of muscle pain. Usually an imbalance caused by muscle weakness will lead to mechanical asymmetries, as in the case of the leg-length-inequality syndrome and low back pain. In addition to medical treatment such as needling, physical correction using a heel lift or butt lift should be considered.
The causes of muscle pain just discussed are related to abnormal musculoskeletal mechanics. The second category of causes of muscle pain is related to medical illness, such as autoimmune disorders, infectious diseases, allergies, hormonal and nutritional deficiencies, viscerosomatic pain syndromes, and iatrogenic drug-induced muscle pain syndromes. The relationship of some of these conditions to muscle pain is more difficult to confirm. When such an illness is identified and treated, the muscle pain is reduced or resolved, but clinicians must be cautious about assuming a causal relationship.12
Autoimmune diseases, particularly connective tissue diseases, also create passive acu-reflex points. For any muscular pain of head, neck, or shoulder, the possibility of polymyalgia rheumatica must certainly be considered. Even though needling helps relieve the pain, consulting a physician for the appropriate test is necessary in these cases.
Infectious diseases produce passive acu-reflex points. Lyme disease is perhaps the most prevalent of the infectious diseases associated with myofascial pain. In some patients, intractable widespread muscle pain and chronic fatigue have been positively associated with Lyme disease (in which elevated immunoglobulin G titers and normal immuno-globulin M titers are indicative of past, not recent, exposure). Some affected patients develop joint pain. Post-Lyme disease syndrome is characterized by diffuse joint and muscle pain, fatigue, and subjective cognitive difficulty.13 Other infectious or parasitic diseases also manifest as widespread pain and resemble Lyme disease.
Allergies may cause widespread muscle pain. Food allergy is an example. Needling therapy may offer the relief from both allergy and muscle pain.
Viscerosomatic pain syndromes occur when visceral disorders exist. Internal organs are associated with somatic segmental referred pain syndromes. Endometriosis, for example, is associated with abdominal myofascial pain. Interstitial cystitis and irritable bowel syndrome are associated with chronic pelvic pain syndromes. Liver disease can cause local abdominal and referred shoulder pain that manifest as a regional pain syndrome.
Nutritional deficiencies also cause muscle pain. Vitamin D deficiency is extremely common among patients with musculoskeletal pain.14 Iron deficiency causes a metabolic stress that produces fatigue and muscle pain. Iron deficiency is also associated with restless leg syndrome; in this way, it can cause a secondary aggravation of the muscle pain.
Many drugs can induce muscle pain, and this type of pain is widespread and diffuse. The statin family of cholesterol-lowering drugs is an example.15
This brief review is not complete, but it is evident that muscle pain and the appearance of related passive acu-reflex points can be caused by many different pathologic conditions, and those mentioned are not an exhaustive list. Careful attention should always be paid, and different medical modalities should be considered in complex cases.
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