Pain is an unpleasant sensory experience that can be felt by all living things that have a central nervous system.. On an evolutionary and ethological level, in the natural world, the pain is explained: this emotion keeps us alert and teaches us what we must not approach if we want to survive in the long term.
In our case, it is the nociceptors (nerve endings devoid of primary sensory neurons) which are the receptors that primarily respond to noxious stimuli. These send impulses through neurons afferent to the spinal cord, and this is transmitted to the brain, which interprets the pain signal and causes the body to respond appropriately.
As counterintuitive as it may sound, without pain there is no life, since without the perception of danger the concept of “survival” does not exist. Can you imagine what the life of a human being should be like with an altered perception of pain? You don’t have to think too much either, because below we tell you all about a term broadly related to this idea: central consciousness.
What is central consciousness?
Central sensitization can be defined initially as a pathological process of the nervous system which consists of a decrease in the pain threshold, which causes hypersensitivity to harmful stimuli. This event, known as SC by its acronym, is caused by increased excitability of central nervous system (CNS) neurons, particularly in second-order spinal cord neurons.
In this state of hyperexcitability, the neurons involved are more easily activated by potentially harmful signals and tend to amplify the information received as it is transmitted along the nerve tree.. Thus, it gives rise to a series of pathological images that we will see below.
When one responds so exaggeratedly to a peripheral stimulus, two specific terms are experienced. We tell you succinctly.
Central sensitization cannot be designed without hyperalgesia, as these are two sides of the same coin. The latter term refers to the increased sensitivity to pain and the extreme reaction of the patient. Something that was painful before is now becoming unbearable.
According to the National Cancer Institute (NIH), hyperalgesia is typical of processes that damage nerves or produce chemical changes in the nerve pathways involved in the perception of pain. Post-herpetic neuralgia is a clear example of this, as the site affected by herpes (the cork) may be hypersensitive for 3 months or more after its onset, due to damage to the superficial nerve fibers.
This term is slightly different from the previous one, but it is also indivisible from the central consciousness. Allodynia occurs when the patient experiences abnormal pain in response to a process that does not normally cause itLike rubbing against a surface or simply palpating the affected surface.
There are 3 types of allodynia: static mechanics, dynamic mechanics and thermal mechanics. The former is defined by the perception of pain with light manual pressure, such as touching the surface of the skin.
On the other hand, dynamic mechanical allodynia occurs by the repeated application of gentle stimuli, such as the passing of a cotton ball or a brush. Finally, thermal allodynia occurs when the patient is particularly reluctant to mildly hot or cold weather events.
The two terms are different, but they are housed under the umbrella of central consciousness. The following idea should be clear to you:
Central sensitization: hyperalgesia + allodynia
Causes of central consciousness
The nickname “central” comes from the fact that the problem is in the central nervous system (CNS): the brain and the spinal cord. As we have said, the neurons responsible for pain perception amplify the signal and make it stronger, which is why the patient perceives atypical pain in the face of routine events.
However, neurons not only send amplified signals, but also transmit “wrong” information, producing the body’s abnormal responses to current environmental stimuli. Note that to understand central sensitization, it is necessary to factor in that there are predisposers and precipitants.
Although this series of pathologies is very little known, we know that there is a certain genetic inheritance for their appearance. Central consciousness generally works in family and, in addition, it seems that people who experienced abuse or traumatic events during childhood are more likely to present it..
In predisposed people, there is usually a precipitant or trigger that causes the onset of central sensitization. Something as simple as a viral infection can lead to it, but it usually happens after accidents and serious injury, both physical and emotional..
As studies indicate, a high intensity pain stimulus can be the prelude to a series of functional and morphological alterations in the central nervous system (CNS), which translates into the general picture of central sensitization that concerns us. here.
Some examples of central consciousness
We’ve talked about central consciousness so far as a kind of pathology, but that’s not exactly the case. It is a common event in several diseases characterized by chronic pain. Here are a few.
It is a disorder characterized by the presence of generalized musculoskeletal pain, Which interferes with the patient’s ability to rest, memory and general mood.
Fibromyalgia usually finds its causes in hereditary factors, infections, and physical and emotional trauma. Something like a car accident or traumatic situation can lead to the onset of this chronic condition, even if it does not appear to be. It is estimated that in some countries the total prevalence is in 2.4% of the general population over 20 years (usually between 35 and 55 years), which is 6 to 8 times more common in women than in men.
Chronic fatigue syndrome
Chronic fatigue syndrome is a serious illness that simultaneously affects many systems in the body. This is characterized by severe fatigue which makes routine actions impossible, trouble sleeping, difficulty concentrating, general pain and recurring dizziness.
In the United States alone, it is estimated that between 836,000 and 2.5 million people suffer from chronic fatigue syndrome. It mainly occurs in people between the ages of 40 and 60 and, again, is more common in women than in men.
Irritable bowel syndrome (IBS)
Maybe this pathology seems more to you, right? Well yes, even if you don’t know it in advance, irritable bowel syndrome and central tenderness are highly correlated.
In a society increasingly dominated by stress and worry, IBS affects up to 20% of the world’s population, depending on the population consulted and the socio-economic conditions prevailing there. Several factors code its appearance: genetics, health, diet, cultural and emotional, among others.
The most common symptom of this disease is chronic abdominal pain, accompanied by colic and swelling. which generally relieves completely or partially during the evacuation of the intestines (defecation or ejection of gas). It also causes diarrhea or constipation and mucus in the stool, among others.
Diseases without treatment
Unfortunately, the diseases that exhibit central sensitization are largely unknown and, therefore, the treatments are limited. In most cases, the patient is asked to learn to manage their pain and to minimize it, but it is never completely eliminated..
For example, medications such as pain relievers, antidepressants, and anticonvulsants (epilepsy drugs) have been shown to be effective for some cases of chronic pain, although this is not a universally effective treatment. All this must be accompanied by a solid psychological care of the patient, dominated by physiotherapy, occupational therapy and psychological counseling, among others.
As you may have noticed, the central consciousness is a general pathological picture very little known, because the causes are never elucidated in many patients. If anything is known, it manifests itself in the form of hyperalgesia and allodynia, and is also part of a large number of diseases.
Unfortunately, in most cases little is left but resistance and resignation in patients who suffer from it. Sometimes chronic pain cannot be treated, so all you have to do is live with it and learn how to manage it.
- Azkue, JJ, Ortiz, V., Torre, F., and Aguilera, L. (2007). Central consciousness in the pathophysiology of pain. Bilbao Medical Gazette, 104 (4): p. 136-140.
- Fleming, KC and Volcheck, MM (2015). Central sensitization syndrome and initial assessment of a patient with fibromyalgia: review. Rambam Maimonides Medical Journal, 6 (2).
- M Adams, L. and C Turk, D. (2015). Psychosocial factors and central sensitivity syndromes. Current journals on rheumatology, 11 (2): pages 96-108.
- Serrano-Muñoz, D., Gómez-Soriano, J., Àvila-Martín, G., Galán-Arriero, I., Romero-Muñoz, LM, Taylor, JS, and Panxa-Martín, A. (2016). Central pain awareness in patients with whiplash syndrome: a review. Latin American Journal of Orthopedic Surgery, 1 (3): p. 102-107.
- Solà, JF (2018). Syndromes of central consciousness: towards the structuring of a multidisciplinary concept. Clinical medicine, 151 (2): p. 68-70.