The Many Varieties of Pain

Pain can be a very relative concept, often making it difficult to classify. Everyone has experienced the desperation of not knowing how to explain what they are feeling - I have actually experienced this situation recently. While commenting with my friend about some pain I was feeling in my stomach, almost instantly she asked “Is it a sharp or a dull pain? Does it come from the inside or the outside?” along with other million inquires, which left me paralyzed for a second. Pain is hard to define after all, so where does pain come from, and how do we classify it?


The origin of the word pain comes from the Latin word poena meaning penalty. This makes us think of pain as a punishment for a wrong behavior – even though you were not supposed to ride your bike in that rocky path, you did, and the punishment for that was the pain you felt in your leg once you fell onto the ground. But what about the headache that woke you up that night? Was that any direct response to a wrong behavior? Not necessarily. This kind of “punishment” ideology serves as a very primitive understanding of what pain really is, and the implications of classifying pain requires more than just basic knowledge. The need to understand the types of pain goes beyond curiosity, as it is crucial to direct treatment and diagnosis.
Starting with the most basic classification, the intensity of the pain dictates the urgency of treatment. A scale from 0 to 10 is normally used to rate how intense the pain is, where 10 would be the most intense pain you could feel. This method however is extremely relative and susceptive to bias. Everyone has a different threshold of pain, which refers to how people perceives discomfort. There is no method to measure such threshold and therefore it becomes hard to classify pain using only its intensity. The mental state of the patient can’t be ignored as any environmental factor can cause the brain to provoke or delete the perception of pain.


Next on the list comes the duration of the pain. How long does it last? If the answer to that question is 3 to 6 months, then it is called an acute pain, if it goes over that time than the pain is said to be chronic. It is also possible to experience an acute-on-chronic pain, that being when there is a flash of acute pain overlapping a chronic pain. Now the question you might be asking yourself is if there is a more scientific way to describe the discomfort you have been feeling, and the answer is yes.


There are two main categories - nociceptive and neuropathic pain. The nociceptive type of pain is the most common and functions as a response to a harmful experience. It is responsible for the horrible pain you feel when hitting your toe on the leg of the table, or when you burn yourself attempting to cook that recipe you read online. To understand this type of pain we need to look inside the tissues of the body and into the receptors that transmit information to the brain. The nociceptors are specific types of receptors that when exposed to physical damage triggers a response and transmits the pain signals to the brain. These signals are transmitted along the peripheral nerves and the spinal cord that reaches the brain to deliver the sensation of pain. It is usually a very localized pain, an exception being the visceral pain, that relates to internal organs and spreads around the tissues, being hard to identify the exact source. The treatment includes medications that stops the transmission of pain signals to the brain. Pharmacological analgesia and opioids are both efficient for this purpose, even though they function differently. Opioids are normally used for more intense pain and its intake needs to be carefully monitored as it’s misuse may cause dependence.


Differentiating nociceptive and neuropathic pain may be tricky. Neuropathic pain is caused by the irritation of the somatosensory nervous system that contains a variety of sensory nerves. These nerves responds to injury, which may not relate to actual damage as in the nociceptive case, and sends messages to the brain. It is followed by a sensation of shooting pain which may have a long duration. If the pain does not seem to disappear after a very long time, the signals are said to be malfunctioning and does not relate to any kind of direct injury anymore. Due to this characteristics, the treatment for neuropathic pain must target the damaged nerves, which analgesic and opioids are not able to do. The response is to use medications such as antidepressants and anti-seizure that are neurostimulating and able to alter the conductivity of the nerves, providing some alleviation to the pain. In most of the cases it is not possible to have an 100% recovery from the neuropathic pain, but with the correct assistance you are able to have a significant improvement. An example is the phantom limb pain, resulting from post-amputation of a limb. The nerve endings at the site of amputation continues to send signals to the brain even though the limb no longer makes part of the body - the patient can still feel sensations as cold, tingling and cramping, as if the limb was still there. It is a very unusual experience to think about, as the pain being felt is very abstract. The brain tricks the body into feeling something that is not there. This neuropathic pain may be caused by emotional stress as a result of the amputation.


Even though these are the main two types of pain, there are many implications of pain classification. Much has been discovered in the past years, but the human body still presents many questions and mysteries that we are unable to answer; pain being one of them. An example where a conclusion hasn’t been reached yet is the topic of trigger points, known as sensitive areas in the soft tissue. While some consider this to be a case of nociceptive pain in the muscle tissue, others discuss that it may be caused by nerve damage and would therefore be a neuropathic pain. Sometimes more than one type of pain can be spotted in a patient, and distinguishing them may be challenging. The importance here is not to classify pain but to acknowledge it - your body is trying to tell you something and you can’t ignore this warning. The sooner you tackle the pain, the faster the recovery. Be aware of your body and the surroundings around you, it is a crucial factor to live in harmony with yourself and the environment. 

 

Reference: 

  1. http://www.news-medical.net/health/What-is-the-Difference-Between-Nociceptive-and-Neuropathic-Pain.aspx
  2. https://www.painscience.com/articles/pain-types.php
  3. http://projects.hsl.wisc.edu/GME/PainManagement/session2.4.html
  4. http://www.helpforpain.com/arch2000dec.htm
  5. https://www.painedu.org/articles.asp
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