Spinal cord stimulator and neuropathic pain

1.What is neuropathic pain?

Neuropathic pain, or neuropathic pain as it is also called, is complex chronic pain that is usually accompanied by tissue damage.

With neuropathic pain, the nerve fibers themselves can be damaged. Because of this, injured nerve fibers send incorrect signals to pain centers. In addition, due to injury, nerve function can be disrupted both in the area of ​​injury and in surrounding areas.

One example of neuropathic pain is phantom syndrome, or phantom syndrome.

. This rare condition occurs when an arm or leg is amputated due to disease or injury, but the brain still receives signals of pain in the amputated part of the body and senses the limb and its apparent movement.

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Life without pain?

It is difficult to imagine a person who has never experienced pain in his life. It is highly likely that pain is the first thing one person once turned to another with, asking for help. One can also believe that the history of medicine begins with attempts to treat pain.

Pain protects health. This is often the first signal of trouble in the body. This is its great protective role. It took a long time for people to understand that not all pain needs to be extinguished right away. First you need to understand its cause, find out what disease it indicates. Sometimes only curing the disease overcomes the pain. The doctor understands this.

But a person always and in every possible way tries to get rid of pain if it arises, because it aggravates life, limits working capacity, and makes one become despondent. To overcome it, men drink alcohol or take drugs. Modern women, in order to save themselves from the pain of birth, resort to caesarean section. Passion for it has become a fad in rich countries.

A business person does not tolerate pain because it interferes with his business or career. He wants to get rid of her here and now. And a bad doctor, he believes, is one who cannot eliminate pain right now. If on the path of such a person he meets a thinking and responsible doctor who is not in a hurry to recklessly relieve him of pain without understanding the cause, he does it himself. Fortunately, advertising helpfully suggests that there are medications that immediately kill pain.

But there is pain that causes daily, long-term suffering, the cause of which is irremovable or constantly recurring - advanced cases of cancer, radiculitis, neuralgia, and other diseases and conditions.

What to do in these cases? How to deal with pain in general? What is its significance in a person’s life, is life without pain possible? And if an adult sometimes “deserves” his pain, then what about a child’s pain?

If I’m not mistaken, it was at the XII Congress “Man and Medicine” that issues related to pain relief were first raised. Here is a report from one such symposium, called “News in Pain Therapy.”

Where does it hurt

Pathophysiologists indicate that pain is an unpleasant sensation and emotional experience associated with actual or possible damage to body tissues. This unpleasant sensation and emotional experience has a complex etiological structure. Pain can occur due to exposure to any damaging factor - mechanical trauma, inflammation, swelling, burn, etc. This effect is perceived by special receptors called nociceptive (nociceptor - pain receptor). Moreover, all parts of the nervous system - from peripheral to central - are intact. If soft tissues, bones, and skin are damaged, such pain is called somatic. In case of overstretching of the capsule of hollow or parenchymal organs, ascites, hydrothorax, etc. the resulting pain is called visceral.

Another type of pain is neuropathic. It occurs when there is organic damage or dysfunction of various parts of the nervous system, ranging from peripheral nerves to the cerebral cortex. Neuropathic pain occurs when there is a disruption in the interaction of nociceptive and antinociceptive systems, which may be associated with a local organ process (for example, inflammation in an organ) or disorders at various levels of the nervous system. The role of peripheral nerves and roots seems to be the most studied.

There is pain due to impaired perception. It can be provoked by severe emotional or psychological stress, hysteria, asthenia, and can manifest itself as delirium of pain. This kind of pain is called psychogenic.

This is the pathophysiological structure of pain, which the doctor should know in terms of choosing not only relief measures, but also the tactics of their use. With nociceptive pain, it is important to first understand the diagnosis, and then resort to measures to alleviate or relieve it. For example, with appendicitis, analgesia before identifying the cause of pain can lead to gross diagnostic errors.

Establishing the origin of pain - nociceptive, neuropathic or psychogenic - will determine the choice of analgesic therapy.

For example, for somatic pain - the use of drugs that suppress the synthesis of inflammatory mediators, limiting the flow of pain impulses from the site of injury (rest of the diseased organ, for example, immobilization for a limb injury), reducing muscle tension, etc. Neuropathic or psychogenic pain will require a different approach.

There are also clinical differences. Nociceptive pain is often acute. Neuropathic - chronic. Neuropathic pain is characterized by allodynia—the appearance of pain or discomfort in response to a stimulus that normally does not cause pain. Pain in such cases occurs from touching the skin with linen or blowing air. With neuropathic pain, hyperesthesia, paresthesia, hyperalgesia, hyperpathia often occur (perversion of sensitivity, characterized by an increase in the threshold of perception, lack of precise localization of sensations that are unpleasant, and a long aftereffect). A typical example of neuropathic pain is neuralgia - trigeminal, postherpetic.

Patients describe neuropathic pain as excruciating, prolonged, and are characterized by the definitions “burning,” “shooting,” “piercing,” “like an electric shock.” Sometimes there is a feeling of pain in the absence of any external influence. In the pathogenesis of neuropathic pain, disturbances of peripheral nerves, roots, the dorsal horn of the spinal cord, pain neurotransmitters, glutamine receptors, sodium and calcium channels are important.

Knowledge of the pathophysiology of pain also determines the choice of therapeutic measures. In somatic pain, an important role is played by suppressing the synthesis of inflammatory mediators (NSAIDs), limiting the entry of pain impulses into the center, activating antinociception, and reducing muscle tension. In neuropathic cases, tricyclic antidepressants, anticonvulsants and antiarrhythmic drugs are of decisive importance. Psychogenic pain is treated by psychiatrists. (Professor M. Kukushkin, Research Institute of General Pathology and Pathophysiology).

Neuropathic pain is a difficult problem

An entire report was devoted to the treatment of neuropathic pain (Professor A. Danilov, I.M. Sechenov Moscow Medical Academy). The complex genesis of this type of pain also determines the complex nature of its treatment. Both medicinal and non-medicinal methods are used. The latter include measures that enhance the activity of antinociceptive systems - acupuncture, transcutaneous electrical neurostimulation, physiotherapy, biofeedback techniques and psychotherapy. Less commonly used are nerve blocks and neurosurgical methods - destruction of the zone of entry of the dorsal root, which can block the flow of afferent nociceptive stimuli. Pharmacotherapy for this type of pain includes drugs with a variety of mechanisms of action - local anesthetics (lidocaine 5% cream or patches), opioids, central muscle relaxants, antiarrhythmic drugs, as well as antidepressants and anticonvulsants. The speaker especially emphasized that for neuropathic pain, simple analgesics (aspirin, paracetamol) and non-steroidal anti-inflammatory drugs (diclofenac, indomethacin, etc.) should not be used, since this pain does not arise from inflammation, but from neuronal and receptor disorders, peripheral or central .

The main focus of the report was on a new drug based on gamma-aminobutyric acid (GABA) and related to anticonvulsants, Neurontin. According to the author, it relieves all types of neuropathic pain associated with both peripheral and central damage. Its valuable quality is its ability to relieve pain in cancer patients. The drug enhances the synthesis of GABA, has a modulating effect on NMDA receptors, blocks calcium channels, reduces the release of monoamines, reduces the synthesis and transport of glutamate, and reduces the frequency of action potentials in peripheral nerves. Side effects of the drug are extremely rare: dizziness and drowsiness. Neurontin is used for peripheral polyneuropathy, postherpetic and trigeminal neuralgia, multiple sclerosis, low back pain, carpal tunnel syndrome and headaches.

Professor A. Danilov noted that men and women feel and react to pain differently, and suggested that in the future, it would probably be necessary to create analgesic agents separately for men and women.

Missed opportunity

In addition to the above reasons, neuropathic pain can occur with cancer. Or, more precisely, the pain experienced by cancer patients is often neuropathic in nature. The report of Candidate of Medical Sciences G. Abuzarova (P.A. Herzen Oncological Research Institute) was devoted to pain in oncological pathology.

Here I would like to make some digression. When it comes to cancer patients, the topic of pain management should be considered not only in purely pharmaceutical terms. These patients are doomed to long-term suffering, which in advanced cases often cannot be stopped, when it is no longer possible to cure the cause of the pain - the cancer itself. It seems that issues of palliative care have never been discussed at the “Man and Medicine” congresses. At the last, XII Congress, this, in my opinion, would have been very appropriate, since clergy, in particular Orthodox priests and hierarchs, took part in its work. One of the main goals of palliative care is precisely the relief and, if possible, relief of pain that can accompany a cancer patient until death. If psychotherapy is used to treat neuropathic pain, then for a religious patient such psychotherapy will undoubtedly be effective, the word of a priest. In European and American medical practice, not only medications are widely used to provide palliative care, but an entire “multi-professional” team is involved, which includes, among other things, a minister of religion, taking into account the religious affiliation of the patient. Awareness of illness and pain as a consequence of a sin and subsequent repentance before a priest can produce a strong psychotherapeutic effect. Scientifically speaking, the efforts of a priest can greatly potentiate the efforts of a doctor. In Russia, as follows from the report of G. Abuzarova, there are more than 2 million cancer patients and their number increases by 455 thousand every year. Of these, from 15 to 35% are patients with the IV, terminal, stage of the cancer process, that is, people those in need of palliative care.

The causes of pain in cancer pathology are varied: trauma to nerve structures, compression of nerve trunks by a tumor, complications of surgical interventions, chemo- and photodynamic therapy. Therefore, pain can be both somatic (visceral) and neuropathic. Hence, the range of drugs is more diverse. This could be metamizole sodium, paracetamol, and their derivatives, NSAIDs. The question of indications for the use of opioids is decided taking into account the severity of the pain syndrome. To assess the severity, a verbal rating scale in points can be used: O - no pain, 1 - mild pain, 2 - moderate, 3 - severe, 4 - unbearable. For mild to moderate pain, the author recommends the use of zaldiar, registered in Russia (325 mg of paracetamol and 37.5 mg of tramadol). For severe pain, potent narcotics are used - buprenorphine, morphine and fentanyl. The duration of treatment with these drugs has no restrictions; they are used for as long as necessary to alleviate the patient’s suffering.

In case of cancer, neuropathic pain may also occur, so there may be indications for the use of the above-mentioned groups of drugs (antidepressants, local anesthetics, etc.). The use of Neurontin may reduce the patient's need for opioids. With complex therapy, it is possible to reduce not only the intensity of pain, but also the area of ​​sensory disorders.

WHO recommends following the following principles when providing pain management to cancer patients:

- immediate start of treatment at the first sign of pain, even minor;

- taking analgesics should precede the onset of pain;

— selection of an individually effective drug;

— detailed information to the patient about the prescribed analgesics and their regimen;

— providing the patient and his relatives with access to a doctor.

About the culture of drug use

The report of Professor G. Gabaeva (MMA named after I.M. Sechenov) on the treatment of migraine made me think about when and how to use medications. The speaker defined migraine as a chronic (that is, recurrent) headache, each attack of which lasts from 4 to 72 hours. According to the speaker, only 1/6 of patients suffering from migraine seek help from a doctor. If headaches occur frequently (more than 2 times a month), the doctor’s efforts should be aimed at preventing them. The main task is to relieve pain. The most effective means are selective 5HT receptor agonists - triptans. Of the non-selective agonists of these receptors, ergotamine is used to stop an attack. Unfortunately, nothing has been said about how to differentiate migraine headaches from non-migraine headaches. Who among us doesn’t have a headache?

* * *

What we heard at this symposium reminded us of one of the brilliant aphorisms of the great actress Faina Ranevskaya: “Health? Health is when you have pain in a different place every day.” There is no life without pain. But there is pain and pain. We can offer the following antithesis to the above definition of health: illness is when it always hurts in the same place. The art of a doctor consists not only in the ability to prescribe a medicine, but also in the ability not to prescribe it. Both the doctor and the patient need to develop a culture of using medications. Then the medicine will not become an indispensable companion in the lives of each of us.

Rudolf ARTAMONOV, professor.

2. Causes of pain

There often seems to be no obvious cause for a patient's neuropathic pain. But doctors identify several types of common causes of such pain:

• Alcoholism;
• Amputation;
• Problems with the back, legs and hip area;
• Chemotherapy;
• Diabetes;
• Facial nerve problems;
• HIV infection or AIDS;
• Multiple sclerosis;
• Shingles;
• Spinal surgery.

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3. Symptoms and diagnosis

Symptoms of neuropathic pain

Signs of neuropathic pain usually include shooting sensations, burning pain, as well as tingling and numbness in the affected parts of the body.

Diagnosis of neuropathic pain

A physical examination is required to diagnose neuropathic pain.

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During it, the doctor will ask you how you can describe your pain, when it occurs, and whether the pain is associated with any specific causes and factors. The doctor may also ask you for blood tests and nervous system test results.
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Exercise in the clinic

Using exercise to treat pain is a relatively new area of ​​research. Doctors cannot yet give unambiguous recommendations about who should do what exercises, for how long and with what intensity. Most of the research on peripheral pain in people involves diabetes, but doctors are reluctant to prescribe exercise to these patients because of the risk of complications such as leg ulcers or increased pain. However, there is ample evidence that people with type 2 diabetes can exercise slowly, with little effort, and as a result achieve pain relief and significant improvements in some nerve functions.

Aerobic exercise is usually prescribed for diabetic patients; it slows down the development of diabetic neuropathy and increases the density of epidermal nerve endings, that is, skin sensitivity, facilitates movement, improves mobility and a sense of balance. Properly selected aerobic exercise helps people with type 2 diabetes maintain peripheral nerve function. There are also reports that diabetic patients can combine aerobic exercise with endurance training without increasing the harmful effects. By combining endurance and balance exercises with exercises on a vibration platform, it was possible to achieve muscle strengthening, an improved sense of balance, and an increase in hemoglobin levels compared to vibration training.

In 2013, researchers found that four weeks of vibration training that simulated the movement of the legs of a person with diabetic peripheral neuropathy significantly reduced pain and made walking easier. Another study reports that whole-body vibration significantly reduces acute pain and reduces chronic pain. Even better results can be achieved if you combine physical activity with medication. Thus, combining antioxidant therapy with exercise is more effective than antioxidants alone in improving plantar pressure in patients with diabetic neuropathies.

Physical activity has been successfully used in the treatment of many diseases, but it is just beginning its journey as a pain reliever. A major problem facing physicians is a lack of understanding of the molecular mechanisms by which exercise reduces pain. What they know is clearly not enough. However, practice shows that exercise can heal some types of pain, although the mechanisms by which it works differ from case to case. The use of training in clinical practice requires active patient participation. To get patients to exercise, they must be convinced that they will feel much better as a result. To achieve this goal, researchers and clinicians must continue to work to be able to present patients with a complete list of symptoms that will be relieved by exercise.

Captions for drawings

Picture 1

Physical training causes changes in all parts of the sensitive nervous system.

• BDNF - brain-derived neurotrophic factor
• GAP43 is a neuromodulin, a multifunctional protein that regulates, among other things, axon growth
• GDNF - glial neurotrophic factor
• NGF - nerve growth factor
• NR1 is a subunit of the NMDA receptor that regulates nociception
• SNAP1 - synapsin 1, regulates the release of neurotransmitters into the synaptic cleft
• TrkA - tropomyosin receptor kinase A, involved in pain perception
• TrkB - tropomyosin tyrosine kinase receptor, brain-derived neurotrophic factor receptor
• TRPV1 is a capsaicin-sensitive receptor involved in the conduction of pain stimuli.
• TRPM8 is a receptor responsible for the body's sensitivity to cold.
• IGF-1 - insulin-like growth factor
• Sub P - substance P - is a multifunctional neuropeptide, including the one responsible for transmitting pain impulses to the central nervous system.

Figure 2

Training normalizes the content of cytokines and growth factors of the sensory nervous system, altered during inflammation. The data was obtained on rats, but also applies to humans.

A.

Inflammation causes changes in the sensory nervous system of rodents. During disease states, including mechanical and thermal hypersensitivity, inflammatory cytokines increase in the dorsal root ganglia, spinal cord, and peripheral tissues.

IN.

After exercise, rats produce anti-inflammatory cytokines that can reduce the content of pro-inflammatory molecules. Increased levels of heat shock protein HSP70 and T cells reduce mechanical and thermal hypersensitivity typically associated with inflamed tissue.

• IF-γ - gamma interferon
• THF-β - transforming growth factor
• IGF-1 is an insulin-like growth factor.