Myogenic back pain

According to modern statistics, the most common cause of back pain is muscle dysfunction.

In modern clinical medicine, two types of myogenic pain (MP) are distinguished: myogenic pain with trigger zones and myogenic pain without trigger zones. If doctors are more or less familiar with the first type ("myofascial pain syndrome" - according to the most common terminology), then the second type, as a rule, is terra incognita for most doctors. When encountering it, in the overwhelming majority of cases, doctors make serious diagnostic and, consequently, therapeutic errors. The first variant is represented by classical myogenic pain, the second - by an interesting symptom complex called fibromyalgia (generalized muscle pain without (trigger zones) and, probably, focal forms of this syndrome - tension headache (TH) without trigger zones and pelvic floor syndrome (PFS) without trigger zones. What we now call tension headache without trigger zones, in the 80s of the last century, the leading specialist in the field of clinical myology, Professor Vladimir Janda, called "limbic hypertonia". He drew the attention of doctors to the fact that in this case there are no typical areas of muscle compaction, and the entire muscle is uniformly painful, and recommended not to waste time on manual treatment of this syndrome, but to treat functional disorders of the central nervous system (emotional brain).

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Myogenic pain syndrome (MPS)

The most probable cause of the formation of a myogenic trigger zone (MTZ) is a violation of neuronal influences on skeletal muscle fiber. The most common cause is abnormal modes of motor neuron functioning with a predominance of static loads, starting from school age. In the presence of somatic pathology or pathology of the musculoskeletal system (osteochondrosis of the spine, osteoarthrosis of the spine) - reflex influences from foci of pathological irritation. In case of organic or functional CNS pathology (stress factors, depression, anxiety, vegetative dystonia, etc.) - a violation of cerebral influences on motor neurons with subsequent functional disorders in the motor neuron-skeletal muscle fiber system.

It is known that if a muscle contains a myogenic trigger zone, its activity is inhibited, manifested by rigidity and weakness of the affected muscle. If the trigger zone is active, muscle activity is significantly inhibited. Thus, a reflex or conscious disuse of the muscle occurs. The main consequence of disuse in muscle fibers is atrophy, especially slow-twitch type I fibers, in addition, a small number of fibers undergo necrosis, and the amount of connective tissue of the endomysium and perimysium increases. Contraction tension and tetanic tension decrease. There is also a tendency for slow-twitch fibers to transform into fast-twitch ones, which is accompanied by changes in the isoforms of myofibrillar proteins. On the surfaces of unused fibers, acetylcholine receptors spread beyond the neuromuscular synapse, the resting potential of the membrane decreases. The motor nerve endings show signs of degeneration in some areas and the formation of branches in others. Finally, after a period of disuse, the motor units cannot be fully recruited. Pain then occurs, closing the vicious circle three times: worsening the disuse of the muscle, worsening the cerebral dysfunction, and disrupting the motor stereotype.

The generally accepted definition of a myogenic trigger zone is that given by J. Travell and D. Simons (1983): it is an area of increased irritability, usually located within tense (compacted) bundles of skeletal muscles or in the muscle fascia. It is painful when compressed, can reflect pain to its characteristic zones, and cause vegetative and proprioceptive disorders. The pain intensifies with muscle tension, especially in a shortened state, with passive stretching of the muscle, with compression of the myogenic trigger zone, with prolonged stay of the affected muscle in a shortened state. In connection with the latter, the pathognomonic phenomenon of increased pain during the first movements after rest is often observed in the clinic, but with continued motor activity the pain significantly decreases or disappears. The pain intensifies with mild jucal cooling, which often affects the next day and is qualified by the patient as "a draft in the neck, lower back, etc." Pain from the myogenic trigger zone decreases after a short rest, slow passive stretching of the affected muscle, using local heat, after light movements. Clinically, the myogenic trigger zone is divided into active and latent, active myogenic trigger zones cause spontaneous pain, while latent ones, forming a pain, are painful only when squeezed, spontaneous pain does not occur. Both forms can transform into each other. It is very important that the force of impact required to activate the latent myogenic trigger zone and provoke pain syndrome depends on the degree of training of the affected muscle: the more it is resistant to physical exercise, the lower the susceptibility of its trigger zone to activating influences.

Myogenic pain reflected from a myogenic trigger zone has a distribution pattern specific to this muscle. Most often, it is distributed within the same dermatome, myotome or sclerotome, but can be partially reflected to other segments. Satellite myogenic trigger zones are formed in muscles that lie in pain irradiation zones from other myogenic trigger zones or in irradiation zones from affected internal organs (central sensitization). This is also a very important pattern.

The course of myogenic pain

Treatment methods should be divided into two groups: pain treatment methods and trigger zone elimination methods. The division is largely arbitrary, since most methods have both effects, but primarily affect one aspect or another.

It is a known clinical fact that the better trained the muscle, the more difficult it is to activate the trigger zone it has. It is also known that myogenic pain decreases as motor activity continues. It is known that myogenic trigger zones are much less common in people engaged in physical labor than in people with low physical activity. In our works, we have shown that the cause of the formation of a myogenic trigger zone is a violation of the trophic effects of the motor neuron on the muscle fiber, and the most physiological and effective method for eliminating the myogenic trigger zone and myogenic pain is to enhance the neurotrophic effects by voluntary activation of motor units in the maximum recruitment mode. This is exactly the mode that T. De Lorma (1945) empirically selected for the rehabilitation of pilots after long-term immobilization of the knee joint.

If the patient has severe pain, it is advisable to start treatment of myogenic pain syndrome (MPS) with pain elimination or reduction, because only after that it is possible to use kinesitherapy methods to eliminate the myogenic trigger zone. The most effective and cost-effective method of treating acute pain is pharmacotherapy: NSAIDs (e.g. diclofenac, lornoxicam) in therapeutic doses for 3-7 days in combination with tizanidine.

Novocainization of the myogenic trigger zone is described in detail in the manuals on the treatment of myofascial trigger zones. It involves the introduction of procaine (novocaine) into the myogenic trigger zone in an amount of several tenths of a milliliter into one myogenic trigger zone. Procaine (novocaine) is the least myotoxic drug among local anesthetic drugs and is most often used in practice. To achieve an analgesic effect, the needle must hit the center of the myogenic trigger zone, which will be evidenced by a local spasmodic response of the muscle. "Dry" puncture of the myogenic trigger zone is also an effective method for reducing pain, if the needle accurately hits the center of the myogenic trigger zone, as evidenced by a local spasmodic response of the muscle. If the procedure is not performed accurately, post-injection pain may be more pronounced than the myogenic pain itself. The same is true for the injection of an anesthetic. Improvement occurs immediately or within 2 weeks. But in the interval of 2-8 hours after the procedure, local pain is experienced by 42% of patients who received an injection of local anesthetic, and 100% of patients who underwent "dry" puncture. It is believed that the main therapeutic factor of both procedures is the rupture of the center of the myogenic trigger zone by the tip of the needle.

The most ancient and simple treatment is the use of heat (heat) to relieve myogenic pain. There are many options for heat therapy, ranging from the use of improvised means to instrumental methods. The mechanism of action of heat is to modify the sensory flow due to afferentation from the thermal receptors of the skin, which inhibits nociceptive afferentation at the level of the posterior horn, and, in addition, improves microcirculation. This method is undoubtedly effective in reducing pain, but it does not eliminate the causative factor (myogenic trigger zone). Therefore, pain relapse occurs quite quickly.

Another type of temperature effect (cooling) is also used to reduce pain. Some authors consider it even more effective than warming. The mechanism of action of the procedure is the same as with warming, the duration of the effect is also insignificant. More effective is a combined method of stretching and cooling the muscle. Here a new important aspect appears - stretching. It is considered the main therapeutic factor, and cooling is an auxiliary one, in addition, it is considered necessary for the patient to do exercises after the procedure, including the affected muscle in the maximum possible volume against the background of warming. Thus, the main sanogenetic moment of the method, called "irrigation with a coolant", is muscle stretching and kinesitherapy.

Ischemic muscle compression (or pressur) is often used to treat the myogenic trigger zone of superficial muscles. The essence of the procedure is to compress the myogenic trigger zone for about one minute to the pain tolerance threshold. The mechanism of the therapeutic effect of the procedure is to create a "counterbalance" nociceptive flow or hyperstimulation analgesia. From a modern perspective, it can be added that with such intensive methods of exposure, the pathological algic system is also destabilized, which facilitates its elimination by other methods. The history of the method goes back to ancient Eastern shiatsu and acupressure, where the technique of finger pressure on specific points is used to harmonize the circulation of chi energy. The effectiveness of the procedure is quite high, but pain relapses are also quite frequent. Recently, there have been reports that metabolic processes may underlie the mechanical effect on the cell. It is proposed that excitation of a hypothetical mechanoreceptor of the cell membrane can initiate a cascade of processes through the activation of G proteins, leading to changes in gene expression.

Classical massage is probably the most expensive method of treating myogenic trigger zone in terms of "man-hours" per patient. In addition, massage has one significant drawback - massage therapists do not wait for tissue relaxation (unlike specialists in manual medicine), which can cause reflex muscle spasm and increased pain. Exacerbation of pain after massage sessions is not uncommon in clinical practice. An improved version of classical massage is longitudinal massage, massage according to JHCyriax. At the end of the course of treatment, the pain often recurs, and the treatment itself sometimes requires a large number of sessions. Currently, the technique of passive stretching of soft tissues has become widespread under the name "myofascial release". A considerable number of specialists have appeared who claim to be the author. It should be remembered that this technique is probably as old as the experience of healing, and modern techniques are described by the above-mentioned authors.

Of the manual methods of therapy for MB and MTZ, the most physiological is the method of post-isometric muscle relaxation proposed by KXewit (1981), the essence of which lies in slow stretching of the muscle in combination with its minimal isometric work. The method is highly effective if performed correctly, which requires significant time. The effectiveness of the method is due to both the activation of the pain gate control due to increased proprioceptive afferentation (along the Aa and Ab fibers), and the increase in the metabolic activity of the muscle fiber during passive stretching and isometric work. When performing post-isometric relaxation, it is possible to use the mechanism of reciprocal spinal muscle relaxation by alternating contraction of agonists and antagonists proposed by Knott M. (1964) and Rubin D. (1981). This method, called the proprioceptive facilitation method, can cause severe pain in the antagonist muscles due to their tension in the shortened state.

Physiotherapy for myogenic pain includes the use of ultrasound, sinusoidally modulated currents, alternating magnetic fields, and laser radiation. There is a report of the high efficiency of direct repeated magnetic stimulation of the muscle in the treatment of myogenic pain.

Mobilization of one's own reserves of antinociceptive defense, activation of cortical descending projections, optimization of the motor stereotype is being intensively developed by specialists in biofeedback with good therapeutic results.

Among the latest achievements in medicine, it is necessary to mention the creation of a special form of botulinum toxin type A and its use for the treatment of myogenic pain. Botulinum toxin, irreversibly blocking exocytosis in the presynaptic ending of the neuromuscular synapse, produces chemical denervation of the mouse, which results in the elimination of the myogenic trigger zone and the cessation of myogenic pain. The treatment method is simple to perform and does not require significant time. Only for the treatment of the myogenic trigger zone of deep muscles, such as the scalene, iliopsoas, piriformis, x-ray control is necessary during the procedure. The effect of the drug lasts about 3-4 months (minimum). The pain resumes after reinnervation of the muscle fibers that formed the myogenic trigger zone. Disadvantages of the method are the high cost of botulinum toxin, the possibility of developing antibodies to it. However, if we compare the cost of the botulinum toxin injection procedure with the cost of treatment with other methods for 3-4 months (the period of effectiveness of botulinum toxin), adding to this the cost of time spent on travel and procedures, then the cost of treatment with botulinum toxin will probably be less than traditional methods. Currently, methods of treatment with botulinum toxin have been developed and are successfully used for the following types of myogenic and combined pain: thoracic outlet syndrome, algic syndrome of the shoulder adductors (scapulohumeral periarthritis), tension headache, migraine, cervicogenic headache, painful dysfunction of the temporomandibular joint, myogenic pain in the limbs (including pain caused by the myogenic trigger zone of the piriformis, iliopsoas muscles), pain in myogenic tunnel neuropathies. Focal muscular dystonias, often accompanied by excruciating intractable pain (spasmodic torticollis, facial hemispasm, paraspasm, blepharospasm), post-stroke spasticity with pain, are effectively treated with botulinum toxin, which is the only effective drug in these situations.