… well, kind of
We all feel it. We can all describe its many faces – sharp, dull, aching, stinging, burning, throbbing, nagging. You get the idea. But what is pain really? Where does it start and how can we better manage it?
What is pain?
Pain is described in the dictionary as ‘an unpleasant sensory and emotional experience that is felt in the body’.
It may seem strange, but pain doesn’t actually exist at the site of the problem. It’s all in your head. Or more specifically, in your brain.
All throughout our body our peripheral nervous system contains high-threshold neurons called primary nociceptors. These neurons are found in the skin, muscles, bones, internal organs: in fact everywhere except the brain. They detect danger and transmit this message to the dorsal horn of the spinal cord. Within the spinal cord are secondary nociceptors, which combine the messages from the primary nociceptors with other sensory messages (sight, sound, smell) and act as a relay station, transmitting these signals to the brain. All this happens in fractions of a second.
Primary nociceptors detect danger in three forms – mechanical (potentially causing a wound), thermal (potentially causing a burn or freeze) and chemical (potentially causing illness). They are multimodal, so can detect danger from one or more stimuli at once. However, they cannot detect the type of danger. This is done by the additional sensory information received by the secondary nociceptors.
Secondary nociceptors filter and prioritise the transmissions received, controlling the speed and strength of the messages going to the brain. So if the danger is perceived as extreme, the messages get through to the brain quickly and strongly, allowing the brain to instruct the body within a split second.
What the brain does
Once the nociceptor messages are received by the brain, it responds by sending back the appropriate message – for instance, if you have put your hand on a hot stove, your brain instructs the body to pull back immediately. If the brain perceives that the danger is not acute the nociceptor system becomes less sensitive. This is called descending inhibition. If the brain believes the threat is real and present, the system becomes more sensitive – called descending facilitation.
The brain also sends messages to the autonomic nervous system. This is the system that controls the automatic functions of the body – breathing, heart beating, digestion, blood flow etc. Your brain will send instructions to increase the white cells and platelets in an injury site, helping to begin the injury repair. It may also release naturally-occurring chemicals which suppress pain, which is why sometimes we don’t feel the pain of major injury immediately that it occurs.
This is also why we sometimes feel ‘referred’ pain. The brain doesn’t quite get the message right, and creates a feeling of pain somewhere other than where the damage has occurred.
Types of Pain
There are essentially three types of pain:
Acute – is sudden and often severe. This type of pain is usually explainable and resolves itself within an expected time period. It is generally caused by illness, injury or surgery.
Chronic – can last for months, and is sometimes unexplainable. Often it is the result of an initial illness, injury or surgery that has been resolved and left ongoing pain in its wake.
Neuropathic – this is caused by damage to the nerves. Damaged nerves can misfire and send spontaneous messages to the brain. It is often a tingling/pins and needles type of pain. This is the type of pain that causes ‘phantom limb’ pain in amputees, as the nerve pathways still exist above where the limb has been lost.
So if the brain has so much control over pain, does it control how much pain we feel? Well, yes it does. And so do many other factors. Which explains why some people seem to have a higher ‘pain threshold’ than others.
Factors that can affect your reaction to ‘pain’ include gender, upbringing and social factors, attitude and coping strategies and psychological factors. Genetics also play a part, particularly in the case of neuropathic pain and in how you respond to pain relief medications. One of the most influential factors in how we feel and cope with pain is past experience. Memories, even subconscious ones, can have an enormous impact on how sensitive we are to pain. As pain messages enter our brain they pass through both the frontal and temporal lobes, which means there is a strong cognitive and emotional factor in our experience of pain.
In managing pain there is the obvious solution – medication. Both over the counter and prescribed. And this is an essential factor in the management of both acute and chronic pain. However, particularly with prescribed medications, there is the risk of addiction and side effects.
There are, however, other ways to help cope with pain.
We can slow or stop the messages sent by the nociceptors. This is how local anaesthetic works. It turns off the primary nociceptors in the area where it is applied, so the message of danger does not reach the brain. No brain, no pain.
Of course, the reverse can be true. Inflammation increases the sensitivity of nociceptors, so you feel pain long before there is any real risk of damage.
Since pain is a direct result of the brain’s evaluation of the level of danger, reducing our perception of the danger can be a key to reducing pain. So, if we ‘distract’ the brain our experience of the pain can be reduced. This is one of the reason past experience plays such a large role in our experience of pain – if we are expecting it to hurt, it will. This might ring true if you have ever had one of those extended low level headaches. If you distract yourself with a conversation, reading or exercise the pain will often subside, only to recur the minute you remember you ‘had a headache’.
Recent studies suggest that using Cognitive Behaviour Therapy (CBT) can help with management of chronic pain, which can often prove to be the most difficult to relieve. Long term chronic pain can increase the brain’s perception of danger, increasing our sensitivity. CBT aims to change the way we think and talk to ourselves about pain. Using the right thoughts and words can not only reduce the brain’s perception of danger, but can activate dopamine production, which is one of a number of ‘feel good’ chemicals in our body.
If you are suffering from acute or chronic pain, understanding how the body processes it can be the first step to managing it and feeling well again. For more information call our Hills District Clinic on 9639 7337.