By Dr. Javier Rivera | Apr. 12, 2019 | Posts in English

A symptom such as pain, which all human beings will have had on some occasion -or almost all, because there are always exceptions-, is still a great unknown.

Each pain is different from another, giving the impression that there are thousands of pains. Thus, there is headache, toothache, trigeminal neuralgia, chest pain, neck pain, trapezius contracture, painful shoulder, tennis elbow, arthritic nodules, myocardial infarction, stomach pain, gut pain, renal colic, period pain, low back pain, trochanteritis, knee pain or the multiple pains that can appear in the feet, without forgetting those that have a traumatic origin due to injuries, burns, fractures, etc.

However, despite the fact that all these pains seem different, they share a series of things in common that can help us better understand how this symptom works.

The first common feature of all pain is that, regardless of where it originates, it is felt in the brain. This is because our own brain is the one that produces the pain symptom using the information that comes from any structure in our body, no matter where it comes from.

Therefore, if somebody ever tell you that your pain is in your brain, in your mind or in your head, tell them yes, that they are right, that is indeed where the pain is manufactured, and try to move on to more practical things, like seeing what solution you have instead of wasting more time on where the pain might be.

According to how the pain originates, we classify it into three types: nociceptive, neuropathic and nociplastic (central origin).

Nociceptive pain originates from peripheral structures called receptors. When these receptors are stimulated due to an aggression of any kind, the peripheral nerve pathways carry the information to the specific brain centers so that the brain produces the sensation of pain. This is a localized pain in the affected structure, which is precisely the one that hurts and not another. Some examples of this type of pain are sprains, inflammation, osteoarthritis, ulcers, heart attack or contractures.

Neuropathic pain originates in the peripheral pathways, that is, the nerves through which the pain travels, and occurs when they suffer some type of damage. This pain is not as localized as the previous one and affects the entire territory of the affected nerve. It is the pain of trigeminal neuralgia, carpal tunnel, herpes zoster, sciatica or polyneuropathies.

In nociplastic pain or central origin, the alteration is in the brain nuclei that produce pain, and it is a diffuse, generalized, poorly defined pain that is accompanied by other equally diffuse symptoms such as fatigue, sleep or mood disturbances.

The importance of this classification is that each type of pain is treated in a different way and it is necessary to know it well to choose the treatment correctly and not make mistakes.

Simple analgesics, such as paracetamol or metamizole, and anti-inflammatories are the drugs of choice in nociceptive pain. In cases of severe acute pain, major opioids and also tramadol may be indicated for short periods of time.

Drugs such as pregabalin or gabapentin are the most indicated to control neuropathic pain and should be the first choice in this type of pain.

Central nervous system drugs, especially antidepressants, are indicated for nociplactic pain of central origin. In this type of pain, analgesic drugs or tramadol are of doubtful use and anti-inflammatory drugs and major opioids are contraindicated.

This information must be known, because treating knee pain with pregabalin or antidepressants; or neuropathic pain such as sciatica with major opioids; or diffuse pain as in fibromyalgia with anti-inflammatories, major opioids or corticosteroids, are errors that harm the patient.

Major opioids, and also minor ones such as tramadol, have been marketed for some time for pain of any kind. However, recent studies show that the analgesic effect they produce is quite similar to that of simple analgesics, but the side effects are so important in the long term that they do not compensate for the possible beneficial effect.

However, treatment must always be individualized and adjusted at all times to the needs of each patient. Although this classification helps us better understand and treat pain, it is common for the same person to have a combination of these three types of pain and, in addition, for there to be other associated symptoms that require combined treatments.