- The Nervous System
- The Immune System
The role of the nervous system in the experience of chronic pain
The nervous system is made up of basic units called neurones.
Neurones form networks and this video will show you how signals - which are chemical and electrical in nature - create pathways in the brain. There is a nervous system pathway for every experience, including pain and understanding that it is a complex with many components is helpful. If you have had a traumatic experience in relation to your pain, that trauma experience will become a part of your pain pathway (see section on Trauma)
If you live in chronic pain it is important to know that your nervous system changes in response to pain, and can become somewhat unpredictable when viewed traditionally. The process is called "Central nervous system sensitisation" and it causes the pain experience to become a highly distressing, misunderstood, little explained "snake eating its tail" situation where things can progressively deteriorate.
Your thoughts, feelings, and movements are all players in exciting or inhibiting Central nervous system sensitisation. There are chemicals that are associated with thoughts, feelings and emotions, and some of these calm down the system, some of them excite the system.
The pain experience is related to activity in ascending, central and descending processes of the central nervous system (spinal cord and brain).
Ascending fibres from the body to the brain
- They transmit messages to the brain about damage or threat in the tissues
- Signals can also come to the brain about the health of the nerves themselves. This is called neuropathic or neurogenic pain
- In the spinal cord the central nervous system can become highly sensitive to stimuli from both within and outside the body. This process is referred to as Central Nervous System Sensitisation.
- In this situation, the ongoing pain has a lot to do with the process of nervous system adaptation. It is like the nervous system becoming a very sensitive and high quality amplifier.
Descending Fibres from the brain to the body via the spinal cord
- This involves the sympathetic nervous system (fight or flight),
- Also involves the parasympathetic (rest and digest), endocrine (hormone production), immune (defence) and motor (movement) systems. All of these nerve fibres will make a contribution to the pain experience.
Lorimer Moseley explains the nervous system and pain
How do we know how the nervous system works and what is going on in the brain?
Most of the information we hear about is theoretical, however there is some really interesting information emerging as a result of a technique called "Functional Magnetic Resonance Imaging" which shows pictures of the brain while we are having an experience of some kind.
Here is Dr Christopher DeCharms talking about this technology.
Central Nervous System sensitisation
How does the IMMUNE system affect my pain and what can I do about it?
The immune system works to protect you. It consists of tiny cells which have the ability to communicate with each other and with the cells of the nervous system all the time. This enables the immune system to be aware of everything that is happening in your internal AND external environment, all the time. They can respond to anything that is a potential threat, thereby keeping you safe and ensuring your survival.
To understand how this happens, lets go back to basics.
When you are in pain, there may be a part of that experience of pain that is due to inflammation. Firstly, lets look at what this word means. It comes from the Latin "inflammare" which means "to inflame". The important part of that word is "flame" as in fire. People experiencing inflammation often describe it as hot and burning. Inflammation is a "localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful, especially as a reaction to injury or infection", according to the New Oxford Dictionary of English.
Inflammation is caused by chemicals released by the immune system in response to foreign substances (like if you scratch yourself and some dirt or sand gets into the skin) or if you are exposed to bacteria, viruses or cancers. The immune system releases chemicals which attack "invaders", and there are other immune system chemicals that make the area quite sensitive so that you avoid using it.
The chemicals responsible for inflammation make the surrounding body tissues much more sensitive (this process is called peripheral sensitization). This is why when you fall over and hurt your foot and it becomes inflamed you find that the whole foot is sore, not just the part that you hurt originally. This short-term inflammation is great because you then protect your foot while it heals.
Inflammation can be short-term, like when you bump your knee on the coffee table, but there are some conditions, like osteo-arthritis which can involve long term wear of the joints, and this can then become long-term inflammation. There are also some conditions that can involve long-term inflammation because of over-activity of the immune system. This is called "auto-immunity" where the immune system becomes really sensitive to lots of things and can make people quite sick. Conditions that can involve auto-immunity include rheumatoid arthritis, multiple sclerosis, ulcerative colitis, asthma, Hashimoto's thyroiditis and many others.
Researchers have also found that there is a genetic component in some autoimmune conditions such as rheumatoid arthritis.
By the way, any condition or disease that ends with "-itis" means that inflammation is involved. For example, sinusitis is inflammation in the sinuses. "Arthritis" is inflammation of the joints ("Arth" indicates joints, from the Greek "arthron" meaning joint).
Apart from inflammation there is another way the immune system protects you. When it has attacked an invader it has the ability to remember the invader, so that the next time it comes across it, it is able to more efficiently mount an attack on it. This is the principle behind immunisation such as when we have a tetanus shot or get our children immunised against chickenpox. The immune system can grow immunity against the foreign substance in the body.
The immune system watches over your health, and it can do this both close up but also from a distance. For example, researchers have now shown that when you hurt your finger, apart from your finger becoming inflamed, chemicals become active in your spine too.
These chemicals released in your spine, just like the inflammatory chemicals we just described, can make the nearby tissues in the spinal cord much more sensitive, and your pain can spread and worsen.
What can happen once these spinal cord immune cells become active?
This process seems to contribute to a phenomenon that scientists call "central nervous system sensitisation". Everything becomes more sensitive. This sensitivity makes pain worse - it is like opening the gate for more pain to be experienced.
The release of these chemicals can also cause fever, malaise, fatigue, sleepiness, loss of appetite, loss of libido (sex drive), social withdrawal, irritability and heightened sensitivity to everyday activities causing increased pain (hyperalgesia). This group of symptoms is known as the stress or sickness response.
Once these immune cells of the brain and spinal cord become active many of the clinical features of the puzzling pain condition known as fibromyalgia syndrome can be explained. In fibromyalgia increased pain sensitivity is a prominent feature. There appears to be many possible triggers for this condition, which may be an example of an extended stress of sickness response.
What triggers these spinal cord immune cells to become activated?
We all know what psychological stress is because we experience it from time to time in our daily lives when we are under pressure. There are also other kinds of stress that can trigger our bodies to react and protect itself, these are called "stressors" and can include:
- Nervous system infections and injury
- Prolonged use of codeine or high dose morphine (the development of opioid tolerance and opioid induced hypersensitivity can be at least in part explained this way)
- Physical stress or when we push our body too hard by overdoing exercise or doing too many activities in one day.
- Chronic stress, like being enmeshed in a disputed workers compensation situation or caring for a chronically ill family member, can trigger this immune response
What can I do about it?
Does any of the above sound familiar to you? Are you trapped in a chronically stressful situation? It is possible that your immune system is turned on continuously in an attempt to rectify the situation and protect you.
This is the most important part. One of the first things you can do if you think you are experiencing this process is to look at how you can better manage the stress or stressors in your life. Lifestyle issues such as diet and sleep may also need attention. High doses of marine lipids (such as omega 3 fish oil) have been found useful to combat inflammatory processes in joints and are worthy of consideration by those who prefer not to take non-steroidal anti-inflammatory drugs. Please see the pages on "pacing", "exercising with pain" and "relaxation techniques" to find out more about what you can do.
Watch this ...
Cheryl Wardlaw PT MMSc CFMT gives a guest lecture entitled "The Immune System's Role in Chronic Pain". In her lecture, she discusses the role of the immune system, diet, allergies and GI health on chronic pain. Mrs. Wardlaw is the Manager for Rehabilitation Therapy at Emory University Hospital. In addition to her administrative responsibilities, she also treats complex neurologic and orthopedic outpatients. This lecture was recorded on November 16th, 2011 in Dr. Lampl and Quave's "Predictive Health: Many Diseases, Few Causes" course offered at Emory University in Atlanta, GA.Read More
If you want to read about this topic, our recommendation is to look at "The Brain That Changes Itself" by Dr Norman Doidge. In his book, Dr Doidge tells a number of stories which provide real live evidence of how the brain is where all experience is reflected, including the chronic pain experience.
Dr Chris Hayes: How the brain can change
Dee lives with chronic pain and when she and Coralie got together, the subject of habitual approaches to doing a regular activity arose. Dee loves riding her bike and was using her sore foot to mount her bike - all without thinking. This is a very practical example of how the brain creates neural networks that are involved in pain - and how important it is to challenge these as we learn to unwind and break up pain networks in the brain. Its all about "Neuroplasticity".
Metaflammation is a new term that describes low levels of inflammation throughout the body. When you have a full blown infection your levels are very high. Metaflammation is different. It is much much lower but constant. It has been found to be present in many chronic conditions. Metaflammation is implicated in chronic pain and is affected by diet, exercise, social connection and mindfulness meditation. We will discuss all these aspects of lifestyle elsewhere in this website.
There was an article written in TIME magazine in 2004 that put a spotlight onto this phenomenon:
"... Chronic inflammation also fascinates scientists because it indicates that our bodies may have, from an evolutionary perspective, become victims of their own success. "We evolved as a species because of our ability to fight off microbial invaders," says Dr. Peter Libby, chief of cardiovascular medicine at Brigham and Women's Hospital in Boston. "The strategies our bodies used for survival were important in a time when we didn't have processing plants to purify our water, when we didn't have sewers to protect us." But now that we are living longer, those same inflammatory strategies are more likely to slip beyond our control. Making matters worse, it appears that many of the attributes of a Western lifestyle — such as a diet high in sugars and saturated fats, accompanied by little or no exercise — also make it easier for the body to become inflamed..."
For the full article click the TIME magazine image on the right ...
In Australia Professor Garry Egger has had an interest in this subject. He spoke to the MEDICAL OBSERVER magazine about it and the article can be found by clicking his image on the right ...Read More