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What Happens When We Feel Pain?

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Pain is a complex physiological process that can be difficult to define, locate and treat. Pain is caused, not by the stimulus itself but by the message that is sent by the lightning fast sensory receptors in our body known as nociceptors that are stimulated by temperature, pressure or chemicals. When these pain receptors are stimulated by a trigger, they release neurotransmitters within the cells. Neurotransmitters are chemical messengers in the nervous system that communicate between the nerve cells. When we feel pain, such as when we cut our finger, these neurotransmitters send a message via the nerve fibres along the spinal cord to the thalamus region of the brain where the sensation is interpreted.


Pain isn’t felt until the brain has received this message and transmitted the pain signal from the thalamus to other areas of the brain to be processed and coordinated an appropriate response at the site of the trigger, based on its interpretation. We say interpretation because the brain uses all of the tools at its disposal, including the messages from the cells at the actual site of injury, previous memories and experiences, senses such as what you can see, feel and smell to make a judgement call based on what it thinks the situation requires. Then the level of pain that is determined as appropriate by the brain is sent as a signal that can increase or decrease the severity of the pain response. This all happens so quickly,  and it’s this interpretation that is the difference between a little ‘ouch’ of a paper cut and a ‘call the ambulance I’ve cut off my finger’ levels of pain and reaction.


If the brain doesn’t consider the trigger something of concern, for example, a light brush of a twig against your leg then your brain can signal the release of natural painkillers known as endorphins to reduce the sensation. Alternatively, if the brain deciphers the trigger as harmful, such as a burn when touching a hot surface, it will direct the release of neurotransmitters that enhance pain and hormones that stimulate the immune system to respond to an injury. The amount of neurotransmitters can vary in each person, and also their memories and experiences of previous stimulants, which is why individuals can have greatly varying tolerance for pain.


How pain works


What Are the Types of Pain?

Pain can be categorised into a few different ways. The most general categorisation of pain is either acute or chronic. Acute pain is often caused by damage to tissues such as bone, muscle or organs, typically comes on suddenly and has a limited duration as it resolves once the injury heals. Chronic pain persists for longer than three months and is often resistant to medical treatment. Chronic pain may be due to an ongoing medical condition, such as arthritis or cancer, however, in many cases, it doesn’t have an identifiable cause. 

You can also categorise pain by its origin. Nociceptive pain is caused by tissue damage and may be described as aching or throbbing and neuropathic pain is caused by nerve damage to peripheral nerves, the spinal cord or the brain, and is most often described as a burning or stabbing sensation. There is also psychogenic pain, which is pain that is affected, enhanced or prolonged by psychological factors, such as fear, stress, depression or anxiety. Psychological pain may have originated as nociceptive or neuropathic pain, but after the injury is healed the pain can linger in its psychogenic form. This is one of the reason that makes pain so complex and difficult to treat, in some cases, especially chronic pain there may be no stimulus or injury present, but the brain is still interpreting the message as something to be worried about, so it continues to release neurotransmitters that enhance the sensation of pain. Many interesting studies have been conducted on psychogenic pain that show people feeling physical pain when someone else is injured or using mirrors to trick the brain into thinking there has been an injury and having a pain response when in fact there hasn’t been any stimulus applied. It’s an area of study that is particularly interesting when considering the psychological factors of chronic pain. Melbourne osteopath, Ben Glynn explains that the first pillar of treatment for chronic pain is to understand the connection between mind and body when it comes to pain response. “Due to the complex layers of chronic pain, one of the most important aspects of effective management is to educate a patient to understand the physiological source coupled with the psychological associations and the genuine effects on the local tissues.” 


How Does Ice & Heat Work to Treat Pain?

Ice therapy, otherwise know as 'cold therapy' or 'cryotherapy' can be used to control pain, swelling, and inflammation which then helps to reduce restriction and enhances mobility. The therapeutic effects of cold generally result from its actions on metabolic, neuromuscular, and hemodynamic (blood flow) processes. Applying a cold compress may decrease nociceptive input and pain perception through  nervous system pathways.  The cold causes blood vessels to constrict and decrease the conduction of nerves at the affected area. When the neurons are cooled it causes the ion channels to open more slowly, which reduces the speed of the axon potential (nerve communication), effectively slowing the pain message to the brain. Cold therapy is considered most effective for acute nociceptive pain and research shows that icing with compression for 10 to 15 minutes can go beyond immediate changes and produce pain reductions for more than 1 hour. It's best to use cold when the pain is still acute.

Applying superficial heat will influence tissue healing and acute nociceptive pain generation which is shown to be effective in the treatment of chronic pain. When applying a heat pack there is a mild increase in tissue temperature, which makes more oxygen available and an increase in enzyme activity results in more oxygen being taken in by the cells, thus enhancing tissue repair. Mild heat is shown to reduce skeletal muscle tone and spasm by lowering alpha motor neuron firing rates that may lead to a break in the pain-spasm-pain exacerbation cycle. Heat packs can be useful for chronic conditions as it also stimulates the sensory receptors to block the transmission of pain signals by providing a counter stimulus to compete with pain perception in the thalamus, resulting in pain relief.

Chronic and psychogenic pain can last for months or years, be constant or intermittent, and vary in severity over time. Living with daily or long-term pain is physically and emotionally stressful. Chronic stress is known to change the levels of stress hormones and neurochemicals found within your brain and nervous system that can eventually influence your mood, thinking and behaviour and impact on your everyday life. Recovering from injury, surgery or living with chronic pain can affect your ability to function at home and work or cause sleep disturbances, fatigue and trouble concentrating. If you are suffering from any type of pain it is important to connect to health professionals and seek help to recover both physically and mentally.

Ice and heat pack for ankle

Our BodyICE Recovery ice and heat packs are designed to be joint specific and to help provide natural pain relief alongside other therapies and treatment programs such as physiotherapy and physical rehabilitation.

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