Pain Science

Pain Science

Contents

  1. What is pain?
  2. Different types of pain
  3. How does the brain generate pain?
  4. What is chronic pain?
  5. How can we measure pain?
  6. How can pain be treated?

What is pain?

Can you imagine a life without pain? Bliss, right? The International Association for the Study of Pain suggests that pain is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.”[1] But pain actually serves a vital purpose for humans, and anything living with a nervous system. The sensation of pain warns us to avoid a situation or location that may cause us harm – it's almost like a guardian without you even realising it! Pain indicates that the body requires protection and/or healing. So, while our initial reaction to pain is usually negative, it actually benefits us and is critical to our survival.

Different types of pain

So what are the different types of pain? Although we generally refer to anything that hurts as ‘pain’, there are actually many different types of pain with unique factors and treatments. Some of these include Nociceptive pain, Neuropathic pain and Psychogenic pain.

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Nociceptive Pain

The majority of pain you experience is nociceptive pain. This pain is caused by damage to body tissue and is the stimulation of a type of peripheral nerve fibre, known as nociceptors. You may feel this type of pain when you stub your toe, touch a hot dish, cut yourself, and anything else that causes tissue damage. When we look more closely at nociceptive pain, we can see that there are various types of stimulus that cause the pain or causes where the person feels the pain. We can break this into three types:

  1. Mechanical stimuli – This is when injuries are caused by cuts, bruises, sprains or breaks.
  2. Chemical stimuli – This is when a substance harms the body causing things like chemical burns.
  3. Thermal stimuli – This is usually from extreme temperature changes leading to injuries and pain like burns from heat and frostbite.

Nociceptive pain also depends on which part of the body it affects. This can also be categorised:

  1. Superficial Somatic pain – caused by injuries to the skin, usually easy to locate and causes a sharp, specific area of pain. Types include cuts, bruises and burns.
  2. Somatic pain – occurs when a wound is deeper including injuries to tendons, ligaments, broken bones and pulled muscles.
  3. Visceral pain – originates in the organs and is far more difficult to target. Types of this pain include digestive diseases and disorders.

Neuropathic Pain

The other main type of pain is neuropathic pain. This occurs when an injury directly affects the nervous system itself – in a mild case, it’s like when you hit your ‘funny bone’ and you get that unusual tingling sensation. This type of pain is different to nociceptive pain as it doesn’t cause achiness, throbbing or sharp pain, instead, it causes pins and needles, numbness, itching, coldness and a burning sensation. This type of pain is more common in chronic pain and central nervous system damage such as multiple sclerosis or spinal cord injuries.

Psychogenic Pain

Lastly, psychogenic pain occurs from mental or emotional causes. It is not an official diagnostic term, but it refers to the psychological side of pain. It can be felt all over the body commonly presenting itself through headaches, muscle aches, back pain and abdominal pain. Since most pain occurs in the brain, mental illness and emotions can have an enormous impact on how we interpret pain signals. We often see this form of pain in those that suffer with Irritable Bowel Syndrome (IBS), whereby the pain in their bowels is often triggered by stress or mental health issues.

How does the brain generate pain?

Have you ever wondered how we perceive pain? We know it hurts, and our bodies are intelligent enough to detect danger and pain, but have you ever wondered how?

Underneath our skin surface we have an intricate network of pain nerve fibres that end with receptors called nociceptors. When we feel pain, a pain message is transmitted to the brain by nociceptors which release the perception of pain. The nociceptors can be triggered by various things like thermal, mechanical or chemical stimuli (as shown above).

Once the pain message has been transferred, the signals travel along different types of pain nerve fibres. These fibres are known as A-delta fibres and C-fibres. This message is sent to the spinal cord and brainstem, and then to the brain, where the pain sensation is registered, processed, and perceived. Incoming signals can be “amplified, attenuated or reappraised by the brain”, which can significantly adjust the individual’s experience. Pain medicine can reduce or block these messages before they reach the brain to minimise the pain, so this is frequently used in medical environments.

What is Chronic Pain?

Chronic pain is a persistent pain that continues past the usual recovery time with one in five adults suffering from it.[2] Types of chronic pain include things like arthritis, neck pain, back pain, digestive issues, muscle pain, headaches (migraines), alongside many more symptoms.

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What causes chronic pain?

Chronic pain can be caused by a variety of factors. It could be the result of an illness or injury that you recovered from a long time ago, but the pain persists, or it could be the result of an ongoing cause of pain such as arthritis. A lot of chronic pain occurs after an injury where it is evident that pain once occurred.

Types of physical pain

There are two types of physical pain including chronic pain and acute pain. The difference between the two is that chronic pain persists for months or even years, while acute pain comes from inflammation, tissue damage or injury, so tends to only last a couple weeks through treatment.

Inflammation

Inflammation is one way the body reacts to cellular injury. The role of inflammation in pain sensitivity is one of the most basic aspects of pain physiology.[3] In addition to pain, inflammation causes swelling, redness, and heat, making it easier to see when pain has occurred. For example, Arthritis is a painful inflammatory disease of the joints causing joint stiffness after periods of rest or inactivity.

Acute inflammation can cause throbbing, pulsating, stabbing, or pinching sensations and the build-up of fluid leads to swelling. This pressure causes discomfort, and pain signals are sent to the brain. Joel Seedman, a personal trainer, suggests that “high levels of chronic inflammation are associated with bad health, pain, and reduced function in gait pattern, walking speed, strength, stability, and mobility”.

Posture and Muscle Pain

Daily posture is often believed to impact the risk of chronic pain. While you may initially believe that bad posture and pain were linked, some studies arguably suggest that “ if any correlation exists between posture and pain, it is weak.”[4]

Joel Seedman’s research in  ‘The Truth about Pain Science and Biomechanics’ demonstrates a connection between poor posture and inflammation, but doesn’t suggest that inflammation is caused by poor posture.[5] Most studies suggest that habitual postural patterns are linked with musculoskeletal pain and inflammation, so improving your posture could lead to improvements.

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How can we measure pain?

While we often try to put on a brave face to cope with pain, it's important to communicate when we're in pain so that others can offer compassion and support. When people are in a lot of pain, they tend to cry out in agony, but if it's not visible, doctors often use a pain scale to determine the severity of a patients discomfort.

Pain Scale

A pain scale is used to assess a person’s pain. It is a simple way of ‘rating’ the level of pain using a scale from 0-10 (0 being low, and 10 being intense pain). This scale allows medics to understand the severity, duration and type of pain that someone is feeling. They can also support making an accurate diagnosis by creating a treatment plan based on the results and measuring the effectiveness of any treatment trialled. You will usually have a pain scale test/questionnaire if you are admitted to hospital, going to a doctor’s appointment or after surgery.

So while the measurement of pain isn’t always a straightforward answer, there are ways to understand someone’s pain through questionnaires and scales. Otherwise, physical scans or blood test results can suggest the amount of pain a person is in which can help with treatment too.

How can pain be treated?

There are many types of treatment available for different areas of pain that your doctor can provide you with. Seek medical advice when discussing pain treatments to ensure that you are receiving the most suited relief for your pain.

Analgesics

Analgesics, also known as pain killers, are medications that relieve different types of pain. Non-steroidal anti-inflammatory drugs (NSAIDs) prevent you from producing compounds called prostaglandins which help to avoid inflammation. One popular analgesic which is commonly used to treat inflammation is ibuprofen.

There are various types of analgesics to suit different types of pain. Here’s a few:

  • Acetaminophen – used to relieve types of pain by increasing the body’s pain threshold, modifying how your brain perceives the pain to reduce severity. An example of this is Tylenol.
  • Opioids – narcotic agents that bind to opioid receptors in the brain to modify pain messages. They frequently cause nausea, constipation, drowsiness, and itching, among other side effects. They can also be highly addictive so are prescribed in low dosages to avoid the risk of building a tolerance to them. Examples of this are morphine, codeine, oxycodone, and fentanyl.
  • Adjuvant Analgesics – these medicines aren’t typical analgesics, instead they often only work in very specific situations most commonly used as muscle relaxants, anti-anxiety medicine and anti-depressants.

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Other Treatments

If your pain is not severe then you might want to try an alternative treatment to pain medication.

Here are a few things to try:

  • Exercise – depending on your pain/severity of pain, exercise can boost your wellbeing making you feel better in the long-run.
  • Chiropractor – if you’re facing a lot of physical pain, visit a chiropractor. They are trained to diagnose, manage and prevent disorders of the musculoskeletal system.
  • Take supplements and vitamins – certain vitamins and supplements can support the wellbeing of different parts of your body. Discuss this with your doctor for more information on what to take.
  • Relaxation techniques – Try doing some yoga and meditation to relieve any stress and built up tension in your body. Stress can have an enormous impact on your body so relieving some stress could be the first step to treating your pain.

So, while it is unpleasant to be in pain, it is necessary for survival. Pain drives action and prompts us to avoid danger. It’s  a bodily ‘alerting system’ that we need to survive. 

If you are concerned about the severity of your pain then seek medical advice for guidance on treating your symptoms.

Sources:

  1. Owww! The science of pain, Science News for Students. https://www.sciencenewsforstudents.org/article/owww-science-pain
  2. The Body, What is pain?, BBC Science Focus Magazine. https://www.sciencefocus.com/the-human-body/what-is-pain/
  3. The Science of Pain, Gastrointestinal Society. https://badgut.org/information-centre/a-z-digestive-topics/the-science-of-pain/
  4. The Real Truth About Pain Science & Body Mechanics: A Response to Criticism, Physio Network. https://www.physio-network.com/blog/the-real-truth-about-pain-science-and-body-mechanics-a-response-to-criticism/