The 5 differences between nociceptive pain and neuropathic pain

Among the advances and scientific knowledge brought by the 20th century is a 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, depending on its cause and specific course, pain has been divided into three main types: neuropathic, nociceptive and psychogenic. In this article we will see what are the main characteristics of these types, as well as the differences between neuropathic pain and nociceptive pain.

• Related article: "Chronic pain: what it is and how it is treated from Psychology"

Types of pain and its characteristics

According to the International Association for the Study of Pain, "pain is a sensory experience and unpleasant emotional with actual or potential tissue damage or described in terms of such damage. (1994).

According to its functions and location, said 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 organism 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 organism from a harmful stimulus. An example would be to withdraw the hand when we start to feel a hot object.

this kind of pain It is understood as an alert mechanism, an alarm signal or as an adaptive reaction to real or apparent noxious stimuli. The latter, the noxious stimuli, are transmitted through messages that are also known as “nociceptive messages”. They start at the periphery and progress to the dorsal horn of the medulla, and then to different structures that allow it to reach the thalamus and the cortex (considered the superior centers of the pain).

In the same sense, nociceptive pain receptors can be found in the skin, muscles, joints or vice versa. For the same reason, it is a well-localized pain that the person can write without much difficulty. A persistent experience of nociceptive pain can also provoke a series of local sympathetic effects, muscle contractions and postural changes.

• You may be interested in: "Nociceptors (pain receptors): definition and types"

2. Neuropathic pain

For its part, neuropathic pain is pain that 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 nerve pathways. It develops before a noxious stimulus, but it can also do without it. For their description, people often use unusual terms, while represents a new and difficult experience to describe.

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 sensation pain, burning or burning.
• hyperalgesia: as an excessive or exaggerated response.
• allodynia: through perceiving any stimulus as painful.

Furthermore, neuropathic pain can be divided into the following types based on the specific location:

2.1.Pain of central origin

This may be the case, for example, of a cardiovascular accident or multiple sclerosis. Its location is in the central nervous system and pain is usually more resistant to treatment.

2.2. pain of peripheral origin

In this case it is a pain that has a generally favorable response to treatment and originates in areas of the peripheral nervous system. Over time, this type of neuropathic pain can develop not only as peripheral pain but also as central pain, through a process called precisely "centralization" and characterized by having plastic changes in the posterior horn of the spinal cord.

3. psychogenic pain

Psychogenic pain is called 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 tissue damage has occurred or not. It is an experience of pain that has its genesis in a psychological state, and that it 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) in the following five points.

1. the stimulus

In the case of nociceptive pain, the stimulus that causes the pain is obvious 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 localization

Related to the above, the place where the pain occurs is easily located by the person who experiences it, therefore it is easily described. For his part, neuropathic pain is generally diffusely localized.

3. The description and its characteristics

The experience reported by people with nociceptive pain is often similar. On the other hand, the experience reported by people with neuropathic pain is difficult to report, it seems to be an unusual and different pain, for which reason it's harder to explain and may vary from person to person.

4. The response to the narcotic

The differences in the responses to drug treatment in both cases are also different. While an effective effect has been reported for nociceptive pain, in the case of neuropathic pain partial relief has been reported.

5. The response to placebos

Contrary to the above, neuropathic pain usually responds better to treatments placebos, 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.

Bibliographic references:

• ChangePain (2018) How is chronic pain defined? Retrieved August 9, 2018. Available in http://www.change-pain.org/grt-change-pain-portal/change_pain_home/chronic_pain/insight/definition/es_ES/324800317.jsp.
• Cruciani, R.A., Nieto, M.J. (2006). Pathophysiology and treatment of neuropathic pain: latest advances. Magazine of the Spanish Pain Society. 5: 312-327.
• Perena, M.J., Perena, M.F., Rodrigo-Royo, M.D., et al. (2000). Neuroanatomy of pain. Magazine of the Spanish Pain Society (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 in 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.