This detailed manual, the second volume of a larger work, extensively catalogs myofascial trigger points in the muscles of the lower extremities and pelvis, describing their anatomy, referred pain patterns, and clinical examination. The text provides diagnostic information and treatment approaches, including injection techniques, stretching exercises, and corrective actions for various muscle groups such as the quadratus lumborum, hamstrings, and intrinsic foot muscles. Furthermore, it addresses perpetuating factors like postural imbalances and leg length discrepancies, distinguishing myofascial pain from other conditions like nerve entrapment and fibromyalgia. The manual serves as a comprehensive guide for understanding and managing myofascial pain syndromes in the lower body.
Trigger point pain originates from myofascial trigger points (TrPs), which are hyperirritable spots within a taut band of skeletal muscle or in the muscle's fascia. These spots are painful on compression and can give rise to characteristic referred pain, tenderness, and autonomic phenomena. Myofascial trigger points are distinct from cutaneous, ligamentous, periosteal, and nonmuscular fascial trigger points.
A key characteristic of trigger point pain is that it is referred, meaning the pain arises in the trigger point but is felt at a distance, often entirely remote from its source. The pattern of referred pain is reproducibly related to its site of origin. For example:
Trigger points in the quadratus lumborum muscle can refer pain to the sacroiliac (SI) joint, lower buttock, and sometimes even to the front of the thigh.
TrPs in the gluteus minimus muscle can refer pain over the lower lateral buttock, down the lateral aspect of the thigh, knee, and leg to the ankle, mimicking sciatica.
Failure to recognize that the painful area is usually the pain reference zone, not the location of the TrP, can lead to misdiagnosis.
The sources distinguish between active and latent myofascial trigger points.
An active myofascial trigger point is symptomatic with respect to pain; it causes a pattern of referred pain at rest and/or on motion that is specific for that muscle. It is also tender, prevents full lengthening of the muscle, weakens the muscle, usually refers pain on direct compression, mediates a local twitch response, causes tenderness in the pain reference zone, and often produces specific referred autonomic phenomena.
A latent myofascial trigger point is not explicitly defined in this excerpt but is mentioned as something to be distinguished from an active one. It can be inferred that latent TrPs are not currently causing pain but have the potential to become active. Shortening activation can turn latent myofascial trigger points active due to unaccustomed sudden shortening of the muscle during stretch therapy of its antagonist, leading to increased tension and referred pain.
Trigger point pain is a central component of myofascial pain syndrome, which is characterized by pain, tenderness, and autonomic phenomena referred from active myofascial trigger points, along with associated dysfunction. This syndrome is often a significant component of somatic dysfunction.
The experience of trigger point pain can vary. It can be described as a deep ache, though TrPs in the sartorius muscle might be described as sharp or tingling. The intensity can range from a mild discomfort to intolerably persistent and excruciatingly severe, as can be the case with pain referred from gluteus minimus TrPs. Palpation of an active TrP often elicits a jump sign, which is a general involuntary pain response of the patient. It can also evoke a local twitch response of the taut muscle fibers.
Trigger points in different muscles of the lower extremities cause specific patterns of referred pain. For example:
Iliopsoas muscle TrPs refer pain in a vertical pattern along the lumbar spine, down to the sacroiliac region, and into the groin and upper anteromedial thigh.
Gluteus maximus muscle TrPs refer pain locally in the buttock region and sometimes to the sacroiliac joint and upper posterior thigh.
Tensor fasciae latae muscle TrPs refer pain and tenderness to the anterolateral thigh over the greater trochanter and down toward the knee.
Hamstring muscles TrPs refer pain to the gluteal fold and the back of the knee, sometimes extending into the calf and posterior thigh.
Tibialis anterior muscle TrPs refer pain and tenderness primarily to the anteromedial aspect of the ankle and over the dorsal and medial surfaces of the great toe.
Soleus muscle TrPs commonly refer pain and tenderness to the heel.
Understanding the concept of referred pain and being familiar with muscle anatomy and trigger point characteristics are crucial for health professionals to become proficient in identifying and treating myofascial pain. Effective management often involves inactivating the trigger points through techniques like ischemic compression, injection, and stretch, along with addressing any mechanical or systemic perpetuating factors.
FAQ on Myofascial Pain and Perpetuating Factors
1. What are myofascial trigger points (TrPs) and how do they relate to pain?
Myofascial trigger points are hyperirritable spots within taut bands of skeletal muscle. They are often associated with palpable nodules and can cause local tenderness as well as referred pain in predictable patterns. The pain experienced in various parts of the body, such as abdominal pain, buttock pain, lumbar pain, pelvic pain, and pain in the extremities, can often be referred from TrPs located in specific muscles.
2. What are perpetuating factors and why are they clinically important in myofascial pain?
Perpetuating factors are conditions or stressors that can maintain the activity and irritability of myofascial trigger points, often hindering the success of treatment. These factors are numerous, frequently underestimated, and may require specialized knowledge to identify their significance. Addressing perpetuating factors is crucial, especially in chronic myofascial pain, as it can be the key difference between successful and failed therapy.
3. What types of mechanical stresses can perpetuate myofascial trigger points?
Mechanical stresses are common culprits in perpetuating TrPs in patients with persistent myofascial pain. These include skeletal asymmetries such as leg length inequality (even a small difference of 0.5 cm can be critical) and a small hemipelvis, as well as skeletal disproportion like a long second metatarsal bone (Morton foot configuration) or short upper arms. Other sources of muscular stress involve ill-fitting furniture, poor posture, muscle abuse, constricting pressure on muscles, and prolonged immobility.
4. How can nutritional inadequacies act as perpetuating factors for myofascial trigger points?
Nutritional inadequacies, particularly suboptimal levels of certain vitamins (like B1, B6, B12, folic acid, and vitamin C) and minerals (like iron, calcium, potassium, and magnesium), can significantly contribute to the persistence of TrPs. Even levels within the low end of the normal range for these nutrients can increase the irritability of trigger points and lead to only temporary relief from myofascial treatment. Deficiencies can impair normal muscle function and energy production, further exacerbating TrP activity.
5. How can hypometabolism (low thyroid function) be related to myofascial pain and trigger points?
Hypometabolism, even in cases where thyroid hormone levels are in the low euthyroid range or just below the "normal" limit, can increase susceptibility to myofascial trigger points and reduce the effectiveness of local therapy. Patients with slightly low thyroid function may experience increased muscle irritability, fatigue, cold intolerance, and muscle pain that worsens in cold weather. Addressing thyroid function can be essential for achieving lasting pain relief in these individuals.
6. What role do psychological factors like anxiety and emotional tension play in perpetuating myofascial trigger points?
High levels of anxiety and emotional tension can manifest as chronic muscle tension, leading to muscle overload and the perpetuation of myofascial trigger points. Patients may unconsciously hold their bodies in tense postures. Addressing the sources of anxiety and teaching relaxation techniques can help reduce this perpetuating factor and improve long-term relief. Additionally, unconscious "testing" of painful movements can also act as a repetitive stressor that maintains TrPs.
7. Can infections or other medical conditions perpetuate myofascial trigger points?
Yes, various infections, such as abscessed teeth, blocked sinuses, and urinary tract infections, can contribute to the development and maintenance of active TrPs, possibly due to the absorption of bacterial or viral toxic products. Additionally, conditions like herpes simplex outbreaks can increase muscle irritability and reactivate TrPs. Addressing these underlying medical issues is often necessary for lasting relief from myofascial pain.
8. How are muscles in the head and neck, like the lateral pterygoid, buccinator, and platysma, involved in myofascial pain, and what can overload them?
Muscles in the head and neck are frequently sites of myofascial trigger points that can cause localized and referred pain, affecting areas like the jaw, cheek, face, and neck. The lateral pterygoid muscle, for example, can be overloaded by excessive gum chewing, nail biting, persistent thumb-sucking, playing wind instruments with a fixed jaw, or maintaining side pressure on the jaw. Trigger points in the buccinator muscle can cause cheek pain and perceived difficulty swallowing. Platysma TrPs often refer a prickling pain to the skin of the mandible and chest. Understanding these muscles' functions and potential sources of overload is important for diagnosis and treatment.
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