Neuropathic pain: causes, symptoms and treatment

Feeling pain at some point is something that happens to everyone.

We hit each other, cut each other or just do a bad move and our nervous system quickly picks up and signals that there is injured tissue and causes us that unwanted, annoying aversive feeling that we call pain. Unwanted but adaptive because it warns us that something is wrong and allows us to take action to fix it.

however, sometimes the pain appears without real problem and ceases to make senseor, as in people with neuropathic pain.

    Pain and its transmission

    The sensation of pain is a mechanism of our body, mainly somatosensory, Which detects the presence of a stimulation or a situation that is damaging or likely to damage our tissues. And this affects us not only on a physical level, but also on an emotional and mental level. The perception of pain allows us to set in motion a series of actions and behaviors that will move us away from the harmful stimulus or prevent it from harming us. It is therefore a mechanism of innate origin but modifiable by experience and habit that allows our survival and prevents our death and our handicap.

    Thus, although we know pain mainly through the subjective experience that it produces, it should be borne in mind that this phenomenon it’s not something that only exists for us, in our imagination. In fact, as much as we are the first concerned with not suffering from pain, it comes from a material process which can be objectively studied by observation and measurement. Thanks to this, we know some objective and verifiable aspects of pain in general and neuropathic pain in particular; otherwise we could not say anything about it.

    What we know about this physiological and psychological process

    Neurologically, pain is felt by activating a series of receptors present in the vast majority of our body., Nociceptors, which in case of breakage, pinching or intense pressure are activated and send signals to the nervous system.

    Specifically, the signal is sent through fibers and ganglia to the posterior stem of the spinal cord, with which they communicate through the use of glutamate and the substance known as substance P. The spinal cord will cause a immediate response in the form of a reflex as it sends the pain signal to the brain (being the most well-known pathway of the spinothalamic bundle).

    However, not always with injury we will not feel pain, having a nerve fiber circuit that can inhibit signal transmission. This circuit is visible when the pain level decreases when rubbing an affected area or its surroundings. Depending on whether the excitatory or inhibitory pain pathways are activated or not, we will eventually perceive a painful sensation. In addition, once the injury is perceived in the brain, it proceeds to send out endorphins which neutralize the pain perception, allowing us to ignore the pain and focus on fighting or escaping the stimulus.

    This would be the process that would normally lead to the perception of pain, but as we said there are people who feel pain without any stimulus that should produce it, people who suffer from neuropathic pain. What happens in these cases?

    Neuropathic pain: what is it and how does it occur?

    It is known as neuropathic pain for the type of pain that appears in situations and settings in which there is not enough intense or harmful stimulation for perceptions of pain to appear. Stimuli that do not normally cause pain produce it. Thus, small rubbing and even certain generally pleasant contacts such as a caress or a kiss can become real torture for people with this type of problem, such as their nervous system perceives them as something extremely painful.

    The type of pain experienced can vary widely depending on the cause of the damage and the level of involvement and responsiveness of the nerve pathways. It is very common to appear as a burning pain, that is, as if you have suffered a burn, or as a puncture or puncture. In some cases, numbness in the area may also occur. The pain can be maintained continuously over time or continue indefinitely.

    Neuropathic pain poses serious challenges for those who suffer from it, maintaining a high level of discomfort and frustration. Many people with this type of pain can end up with anxiety disorders or severe depression, in some cases with suicidal thoughts. It is not uncommon for them to avoid, as far as possible, leaving their home, physical contact with other people and actively limit their social, family and professional life, which is a very disabling condition. . It also causes problems sleeping, which in many cases leads to great fatigue and stress..

    The reason for this disorder is the presence of damage to the somatosensory system, damaging the nerve bundles that transmit somesthetic information to the brain. This damage can be localized in the central and peripheral nervous systems. As a result, pain-transmitting neurons become hyperexcitable and respond with less stimulation, and sometimes even without actual stimulation.

    the causes

    Damage to the nerve pathways that ultimately causes neuropathic pain can come from a wide range of disorders. and conditions, receiving different names for neuropathic pain depending on its cause.

    1. Neurodegenerative diseases

    When neuropathic pain occurs due to damage to the nerve pathways it is logical to think that disorders in which there is an alteration or degeneration of the nerves this type of problem can appear. So, both in diseases such as multiple sclerosis and in some dementia processes, it is possible that pains related to nerve degeneration appear.

    2. Diabetes mellitus

    People with diabetes mellitus may develop changes in the nerve pathways over time, When weakening the nerves produces vascular damage or lack or excess of glucose in the blood. In this case, we would be talking about painful diabetic neuropathies. The most common is diabetic peripheral neuropathy, characterized by paresthesias, burning or cooling sensations, loss of sensation, and pain in the extremities.

    3. Poor nutrition

    Lack of sufficient nutrients in the body can damage and weaken nerve cells., Possibly causing an abnormal reaction of the peripheral nerves.

    4. Viral infections: herpes and HIV

    Some viral infections can cause changes in nerve pathways that can lead to neuropathic pain. It is common in the case of the shingles virus, in which the pain usually appears on both the torso and the face.

    Also in the case of acquired immunodeficiency syndrome or AIDS, caused by HIV, degeneration of the nervous tissue can appear and cause the appearance of pain of this type.

    5. Tumors

    Some cancers and tumors can damage nerve pathways, Both by direct effect of the tumor and to produce a possible pinching of the fibers which lead the painful information.

    6. Trauma, haemorrhages and ischemic accidents

    Whether it is due to partial or complete suffocation of neurons or their pinching with other parts of the body, stroke and head trauma in many cases they can be the cause of neuropathic pain.

    treatments

    Treatment of neuropathic pain is complex and requires a multidisciplinary approach. It’s a chronic disorder, although it is possible to decrease the patient’s pain and greatly improve their quality of life.

    Sometimes the cause of the pain can be treated more or less directly and prevent permanent damage to the nervous tissue, as in some cases of diabetes. Some of the planned treatments are as follows.

    1. Antidepressants

    The use of antidepressants is common to alleviate both the level of pain and its psychological effects. However, they should be used with caution as it is intended to decrease the level of pain and not to calm the patient.

    In the case of antidepressants, it has been shown that those which have a level-regulating effect of pain are those which affect both serotonin and norepinephrine, so SNRI and duloxatin are generally used with some success. They seem to work particularly well in some cases of neuropathic pain resulting from diabetes.

    2. Anticonvulsants

    Drugs used to treat epilepsy have also been found to be very useful against neuropathic diseases, both in sclerosis and viral infections, diabetes and the like. For example, carbamazepine is used as the treatment of choice for trigeminal neuralgiaOne of the most painful disorders affecting the nerves of the face.

    3. Opioids and cannabinoids

    As with pain caused by some types of cancer, substances such as morphine have been used in neuropathic pain. marijuana or other derivatives of opium and cannabis to help reduce and manage pain levels.

    4. Other substances: capsaicin

    In addition to those already discussed, it has been found that other substances such as capsaicin may help fight pain, Either orally, or applied to the skin or subcutaneously.

    5. Transcranial magnetic stimulation

    Stimulation of the nervous centers and the somatic system has been shown to reduce the level of pain in patients with this problem.

    6. Surgery

    If the cause of the pain is localized and its completion is viable, corrective surgery may be applied to help improve and remedy the problem. As a last resort, he could perform an ablation of the damaged nerve tissue.

    In addition, at the medical level, it is possible to block the damaged nerve path, either by drug infiltration or by radiofrequency.

    7. Psychotherapy

    Neuropathic pain often leads patients to exhibit inappropriate coping strategies to deal with everyday events as well as anxiety and depression issues. Psychological treatment and psychotherapy can go a long way through programs and therapies that help cope with and learn to manage pain, establish appropriate routines and action strategies, and facilitate the expression and communication of pain. emotions and sensations produced by them. Its state.

    8. Physiotherapy

    Rehabilitation and physical fitness of the patient can help them become less sensitive to pain and improve their quality of life, and can reduce the intensity and frequency of pain and improve their condition both physically and mentally.

    Bibliographical references:

    • Finnerup, NN et al. (2007). An evidence-based algorithm for the treatment of neuropathic pain. Medscape, General Med; 9 (2): 36
    • O’Connor, AB and Dworkin, RH (2009). Evidence-based treatment of chronic neuropathic pain with non-opioid pharmacotherapy. Neurol of continuous learning throughout life; 15 (5): 70-83.
    • Pérez, I. and Ayuga, F. (sf) Neuropathic pain. Neurology Department of the Virgen de la Salud Hospital in Toledo. SESCAM. Toledo.
    • Valverde, JA (2012). Pharmacological treatment recommendations for neuropathic pain. Neuroaxis, 25 (2).

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