Neuropathic pain: causes, symptoms and treatment.

Pain with no apparent cause. We explain everything you need to know about neuropathic pain.

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

We give ourselves a blow, cut ourselves or simply make a bad gesture and our nervous system quickly picks up and informs us that there is an injured tissue and causes us that undesirable and annoying aversive sensation we call pain. Undesirable but adaptive, since it warns us that something is wrong and allows us to act to remedy it.

However, Sometimes, however, pain appears without there being a real problem and ceases to have any meaning.as occurs in people with neuropathic pain. neuropathic pain.

• Recommended article: "The 8 worst pains suffered by human beings".

Pain and its transmission

The sensation of pain is a mechanism of our organism, mainly somatosensory.The first thing we need to do is to use a "sensing device", which detects the presence of a stimulation or situation that is damaging or has the potential to damage our tissues. And it not only affects us physically, but also emotionally and mentally. The perception of pain allows us to set in motion a series of actions and behaviors that will make us move away from the harmful stimulus or prevent it from damaging us. It is therefore a mechanism of innate origin but modifiable through experience and habit that allows our survival and prevents our death and incapacitation.

Thus, although we know pain primarily through the subjective experience it produces, we must bear in mind that this phenomenon is not something that exists only for us. is not something that exists only for us, in our imagination.. In fact, as much as we are the first ones interested in not suffering pain, it comes from a material process that can be objectively investigated through observation and measurement. Thanks to this we know certain objective and verifiable aspects about pain in general and neuropathic pain in particular; otherwise we would not be able to say anything about it.

What we know about this physiological and psychological process

At the neurological level, pain is experienced by the activation of a series of receptors present in the great majority of our organism, the nociceptors, which are present in the vast majority of our organism.These receptors, the nociceptors, are activated and send signals to the nervous system when there is a breakage, pinching or intense pressure..

Specifically, the signal is sent through fibers and ganglia to the posterior horn of the spinal cord, with which they communicate through the use of glutamate and the substance known as substance P. The medulla will provoke an immediate reflex response while sending the pain signal to the brain (the best known pathway being the spinothalamic bundle).

However, not every time there is a lesion we will feel pain, there is a circuit of nerve fibers that can inhibit the transmission of signals. This circuit is visible when the level of pain decreases when we rub a bruised area or its surroundings. Depending on whether the excitatory or inhibitory pain pathways are activated or not, we will end up perceiving a painful sensation. In addition, once the injury is perceived, the brain proceeds to send endorphins that counteract the painful perception, allowing us to ignore the pain and focus on fighting or escaping from the stimulus.

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

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

Neuropathic pain is the type of pain that appears in situations and contexts in which there is no stimulation sufficiently intense or injurious for pain perceptions to appear. Stimuli that do not normally cause pain produce it. Thus, small frictions and even some generally pleasant contacts such as a caress or a kiss can become a real ordeal for people with this type of problem, since their nervous systems perceive them as extremely painful..

The type of pain experienced can vary greatly depending on the cause of the damage and the level of involvement and reactivity of the nerve pathways. It is very frequent that it appears in the form of burning pain, that is to say as if a burn was suffered, or in the form of pricks or punctures. In some cases numbness of the area may also appear. The pain may be sustained continuously over time or it may come and go.

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

The reason for this disorder is the presence of damage to the somatosensory system, the nerve bundles that transmit somesthetic information to the brain being damaged. This damage can be located both at the central and peripheral nervous system level. As a consequence, the neurons that transmit pain become hyperexcitable and react with a lower amount of stimulation, and sometimes even without real stimulation.

Causes

The damage to the nerve pathways that ends up causing neuropathic pain can stem from a wide number of disorders and conditions, with neuropathic pain receiving different names depending on its cause.

1. Neurodegenerative diseases

As neuropathic pain is caused by damage to the nerve pathways, it is logical to think that disorders in which neuropathic pain it is logical to think that disorders in which there is an alteration or degeneration of the nerves can appear this type of problem. this type of problem can appear. Thus, both in diseases such as multiple sclerosis and in some dementia processes, pain linked to nerve degeneration may appear.

2. Diabetes mellitus

People suffering from diabetes mellitus may, with the passage of time, develop alterations in the nerve pathways as the nerves weaken.This is due to the weakening of the nerves as a result of vascular alterations 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, in which there are paresthesias, burning or cooling sensations, loss of sensitivity and pain in the extremities.

3. Poor nutrition

The absence of sufficient nutrients in the body can cause nerve cells to become altered and weakened.eventually causing the peripheral nerves to react abnormally.

4. Viral infections: Herpes and HIV

Some viral infections can cause a disruption in the nerve pathways leading to neuropathic pain.. It is common in the case of the herpes zoster virus, in which pain usually appears both in the torso and in the face.

Also in the case of acquired immunodeficiency syndrome or AIDS, produced by HIV, a degeneration of the nervous tissue can appear that can cause pain of this type to appear.

5. Tumors

Some cancers and tumors can damage the nerve pathways, both as a direct effect of the tumor and as a direct effect of the tumor.This can be caused by the direct effect of the tumor or by a possible clamping of the fibers that carry the pain information.

6. Trauma, hemorrhages and ischemic accidents

Whether due to partial or complete asphyxia of the neurons or to their impingement on other parts of the organism, cerebrovascular accidents and cranioencephalic trauma can in many cases be the cause of can in many cases be the origin of neuropathic pain.

Treatments

The treatment of neuropathic pain is complex and requires a multidisciplinary approach.. It is a chronic disorder, although it is possible to reduce the patient's pain and greatly improve their quality of life.

Sometimes the reason for the pain can be treated more or less directly and permanent damage to the nerve tissue can be prevented, as in some cases of diabetes. Some of the treatments contemplated are the following.

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, since they are intended to the aim is to reduce the level of pain and not to sedate the patient..

In the case of antidepressants, it has been found that those that have a pain-regulating effect are those that affect both serotonin and norepinephrine, so SNRIs such as duloxatin are often 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 shown to be very useful for neuropathic pain, whether it is caused by sclerosis, viral infections, diabetes or other conditions. For example, carbamazepine is used as the treatment of choice for trigeminal neuralgia, one of the most painful disorders in the world.one 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, marijuana or other opium and cannabis derivatives have been used to help reduce and manage the level of pain caused by neuropathic pain, marijuana or other opium and cannabis derivatives have been used to help reduce and manage the level of pain..

4. Other substances: Capsaicin

In addition to those already discussed, it has been found that other substances such as capsaicin can help to combat pain, either orally or when applied to the skin.either orally or applied to the skin or subcutaneously.

5. Transcranial magnetic stimulation

The stimulation of nerve centers and the somatic system has been shown to reduce the level of pain. 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 it is feasible, corrective surgery can be applied to help improve and correct the problem. As a last resort, ablation of the damaged nerve tissue could be performed..

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

7. Psychotherapy

Neuropathic pain often causes patients to have maladaptive coping strategies to cope with day-to-day events, as well as anxiety and depression problems. Psychological treatment and psychotherapy can contribute greatly through programs and therapies that help to cope and learn how to manage pain, establish routines and appropriate action strategies and facilitate the expression and communication of emotions and sensations produced by their condition.

8. Physiotherapy

Rehabilitation and physical conditioning of the patient can help to make him/her less sensitive to pain and improve his/her quality of life. and improve their quality of life, reducing the intensity and frequency of pain and improving their physical and emotional state.

Bibliographic references:

• Finnerup, N.N. et al. (2007). An evidence based algorithm for the treatment of neurophatic pain. Medscape Gen. Med; 9(2): 36

• O'Connor, A.B. & Dworkin, R.H.(2009). Evidence-based treatment of chronic neuropathic pain using nonopioid pharmacotherapy. Continuum Lifelong Learning Neurol; 15(5): 70-83.

• Pérez, I. and Ayuga, F. (n.d.) Neuropathic pain. Neurology Service of the Hospital Virgen de la Salud de Toledo. SESCAM. Toledo.

• Valverde, J.A. (2012). Pharmacological treatment recommendations for neuropathic pain. Neuroeje, 25 (2).