Two types of experiences based on displeasure but that can be distinguished from each other.
Among the advances and scientific knowledge brought by the 20th century is the detailed description of the physiological mechanisms that allow us to experience pain. From there, the latter has been defined taking into account different elements.
For example, according to its specific cause and course, pain has been divided into three main types: neuropathic, nociceptive, and psychogenic. In this article we will see what the main characteristics of these types are, as well as the differences between neuropathic pain and nociceptive pain.
Types of pain and their characteristics
According to the International Association for Pain Studies, “pain is an unpleasant sensory and emotional experience with actual or potential tissue damage or described in terms of such damage” (1994).
According to its functions and location, this sensory and emotional experience can be classified in the following ways: nociceptive pain, neuropathic pain or psychogenic pain.
1. Nociceptive pain
Also known as somatic pain, nociceptive pain is defined as a normal response of the body to an offensive stimulus, and its goal is to prevent further damage. It is an adaptive pain, which is called nociceptive precisely because its main function is to perceive, alert and protect the body from a harmful stimulus. An example would be to withdraw the hand when we begin to feel a hot object.
This type of pain is understood as an alert mechanism, an alarm signal or as an adaptive reaction to real or apparent noxious stimuli. The latter, noxious stimuli, are transmitted through messages that are also known as “nociceptive messages.” They begin in the periphery and advance towards the dorsal horn of the spinal cord, and later, towards different structures that allow it to reach the thalamus and the cortex (considered the higher centers of pain).
In the same sense, nociceptive pain receptors can be found in the skin, muscles, joints or in the vices. For this reason, it is a well-localized pain that the person can write without much difficulty. A persistent experience of nociceptive pain can also cause a series of local sympathetic effects, muscle contractions and changes in posture.
2. Neuropathic pain
For its part, neuropathic pain is that which is no longer considered an adaptive response, and is characterized by changes in the physiology of the response. This type of pain results from injuries or chronic alterations in peripheral or central nervous pathways. It develops in the face of a noxious stimulus, but it can also do without it. For its description, people often use unusual terms, as it represents a new and difficult to describe experience.
It can present itself through the following forms, which at the same time are part of a hypersensitivity to pain known as hyperpathy:
- Dysesthesia : basal pain, burning, or burning sensation.
- Hyperalgesia : as an excessive or exaggerated response.
- Allodynia : through perceiving any stimulus as painful.
In addition, neuropathic pain can be divided into the following types based on the specific location:
2.1 Pain of central origin
It can be the case, for example, of a cardiovascular accident or multiple sclerosis. Its location is in the central nervous system and it is usually pain that is more resistant to treatment.
2.2. Peripheral origin pain
In this case, it is a pain that has a generally favorable response to treatment and that originates in areas of the peripheral nervous system. Over time, this type of neuropathic pain can develop not only as peripheral but also central pain, through a process that is precisely called “centralization” and is characterized by having plastic changes in the posterior horn of the spinal cord.
3. Psychogenic pain
Psychogenic pain refers to the psychological experience (eg anxiety or depression) described in terms of tissue damage. Such a description can be made in both verbal and behavioral terms, regardless of whether the tissue damage has existed or not. It is an experience of pain that has its genesis in a psychological state, and that is not located in the organic structures of the nervous system.
Differences between neuropathic pain and nociceptive pain
Once the general characteristics of the different types of pain have been described, we can explain and summarize some differences between nociceptive and neuropathic pain. We follow Dagnino (1994) on the following five points.
1. The stimulus
In the case of nociceptive pain, the stimulus that causes the pain is evident and easily located both by the person who experiences it and by the specialist. In the case of neuropathic pain, there is no obvious stimulus.
2. The location
Related to the above, the place where the pain occurs is easily located by the person who experiences it, for the same reason it is easily described. For its part, neuropathic pain is generally diffuse in location.
3. The description and its characteristics
The experience reported by people with nociceptive pain is often similar. For its part, the experience reported by people with neuropathic pain is difficult to report, it seems to be unusual and different pain, so it is more difficult to explain it and it can vary between each person.
4. The response to the narcotic
The differences in the responses to pharmacological treatment in both cases are also different. While in nociceptive pain an effective effect has been reported, in the case of neuropathic pain a partial relief has been reported.
5. The response to placebos
Contrary to the above, neuropathic pain tends to respond better to placebo treatments, and nociceptive pain responds practically ineffectively. According to Dagnino (1994) the figures are 60% effective in the first case, and 20-30% in the second.
- ChangePain (2018) How is chronic pain defined? Retrieved August 9, 2018.Available at http://www.change-pain.org/grt-change-pain-portal/change_pain_home/chronic_pain/insight/definition/es_ES/324800317.jsp.
- Cruciani, RA, Nieto, MJ (2006). Pathophysiology and treatment of neuropathic pain: more recent advances. Magazine of the Spanish Society of Pain. 5: 312-327.
- Perena, MJ, Perena, MF, Rodrigo-Royo, MD, et al. (2000). Neuroanatomy of pain. Journal of the Spanish Society of Pain (7) II: 5-10.
- Dagnino, J. (1994). Definitions and classifications of pain. Bulletin of the School of Medicine. Catholic University of Chile. 23 (3). Retrieved August 9, 2018.Available at http://www.arsmedica.cl/index.php/MED/
- IASP (1994). Part III: (pp 209-214). Classification of Chronic Pain, Second Edition, IASP Task Force on Taxonomy, edited by H. Merskey and N. Bogduk, ISAP Press, Seattle, 1994. http://www.iasp-pain.org.