Understanding the Pain
The pain in IBS is referred to as chronic visceral pain. Visceral pain involves the internal organs – in IBS the intestines or bowels, commonly called the gut. The sensation arises at the level of the body and with IBS is usually increased, and when it goes to the brain where pain is experienced, it often has an emotional effect, which is distressing.
The general pain experience is associated with actual or perceived damage to the body. The concept of perceived damage to the body is very important in IBS, and very typical in chronic pain. The pain is not associated with actual damage to the body that can be seen, like a broken bone.
Thus, chronic abdominal pain in IBS is not associated with structural damage as seen with other gastrointestinal disorders like inflammatory bowel disease or ulcers, but the pain is just as real. Just like chronic headache, there is no visible abnormality.
Most people with chronic abdominal pain in IBS have normal results on blood tests, endoscopy, and x-rays. Despite this, new research shows that IBS has biological features that can be measured. So while no damage or injury is seen on tests certain biological features not easily seen are happening inside the body to produce the pain and other symptoms of IBS.
Above all this involves the alteration of the connections between the brain and the gut, known as the brain-gut axis, the effects on sensation and motility, and ultimately the symptom expression.
Research, using brain-imaging work, shows that given a level of stress people with IBS feel more pain than other people. Those with IBS are hypersensitive, that is they have an increased response that makes a stimulus more painful. They may experience pain from sensations that other people are unaware of (called allodynia) or also have more severe pain than others who may also feel some pain (called hyperalgesia).
How is the pain experienced?
It is important to understand that pain is processed in the brain. In IBS, signals that arise in the bowels are relayed to certain areas of the brain where these signals are experienced as painful sensations, which can be modified by emotional centers that can produce a more noxious, or emotionally distressing, quality.
The brain not only receives information about pain, but it may also influence or modify the information coming from the gut to increase or reduce the signals arising from there. This is called the gate control theory of pain.
Signals between the body to the brain pass through the spinal cord, which can serve as a kind of a “gate.” The brain can also open and close this gate, much like a volume switch on a stereo. Closing the gate decreases signals and blocks pain, while opening the gate increases the signals that reach the brain and amplifies pain.
Things like focused attention or various treatments like hypnosis or meditation close the gate. Things like emotional distress or prolonged stress open the gate. Thus, it is no surprise when someone is running a race and sprains an ankle, the pain may not be felt until the race is over. Or conversely when someone is having a bad day at work, sometimes more minor discomfort may become more painful – all as a result of the brain-gut axis.
In other words, pain is a perception that is interpreted depending on a number of variable factors. The experience of pain involves processing in different areas of the brain where it is influenced not only by sensory input from the body, but also by up and down regulation from the brain depending upon life events, and other psychologic and social factors that modify pain regulation.
All of these interactions differ from person to person, accounting for differences in symptom expression and severity in people with the same condition.
This system is so powerful that its effects can be seen even with structural diseases like ulcerative colitis or Crohn’s disease. It’s well recognized that some people with severe ulcerated disease may feel little or no discomfort, while others with minimal disease may experience very severe pain.
What causes the pain to be more severe?
Several things can make a person with IBS vulnerable to experience something as more painful. Information from the bowels involving things like altered gut bacteria, changes in the gut’s response to foods, or altered gut immune system activation can increase nerve signals going up to the brain and stimulate responses that increase pain perception. This is called visceral hypersensitivity.
Emotional or psychological distress can also increase the pain signals by disrupting the brain’s usual ability to down-regulate, or reduce, the incoming pain signals. In addition, negative experiences stored in the memory like trauma, neglect, or deprivation, can prime the brain and spinal cord (central nervous system) to be even less effective in influencing the incoming nerve signals.
The chronic, or long lasting, pain in IBS is related to the effect of central sensitization, which can happen when pain is continuous or keeps coming back. It modifies the way the central nervous system works causing greater sensitivity so the person more easily experiences pain. In effect, chronic pain over time can cause more pain.
Chronic pain starts to develop from recurrent episodes of acute pain passing through the spinal cord. Research has shown that when people have these signals going to the spinal cord over and over again they have what’s called the wind-up phenomenon. That is, the signal that goes to the brain keeps increasing. It becomes greater than the actual signal originally going to the spinal cord. There’s an amplification effect, and as noted, there is turning up of the volume and the pain gets worse. Then the psychological consequences, as discussed above, further amplify the pain.
When people experience chronic pain it also changes them; their thoughts and feelings about it change. Consider the difference of how one responds to an occasional stomach flu. Because one considers the experience to be short lived, he or she can readily cope with it and expectation is full recovery.
However, with chronic pain it doesn’t end, the expectation changes to a state where it is believed that it will happen again and again. This has consequences such as hypervigilance and selective attention, meaning thinking about it throughout the day even when feeling no pain and even anticipating it will surely come back. Now there is no predictability, the person feels no sense of control and pain is no longer an occasional occurrence, but a seemingly never ending phenomenon.
Thoughts turn to: “Will I ever get better,” or “Why can’t someone help me,” or “Do I have to live with this.” These thoughts, often catastrophic in their nature, create a sense of pessimism and hopelessness that in turn create more distress, which decreases the brain’s ability to down-regulate or control the pain, and so it continues.
The pain becomes chronic not only because it lasts a longer time, but also because it’s a functional and structural change in the body that leads the person to be in a state where the pain is always there.
The structural effects in pain relate to the concept of neuroplasticity; that is, of the nerve cells in the brain to grow and die at different rates. It also relates to the brain’s ability to form new nerves and nerve connections, which is called neurogenesis.
People in chronic pain have a loss of nerve cells in pain control areas. It occurs in severe situations like major depression and anxiety, post-traumatic stress, chronic pain in general, and it occurs in severe IBS.
Chronic pain is not just a biomedical phenomenon, as if the body were a machine with a broken part. Chronic pain is influenced by multiple factors within the biologic, psychologic, and environmental or social framework of the mind, brain, and body.
Although multi-faceted, this all opens the door to treatment, because if the brain can make pain worse then treatments on the brain can make it better. That is why treatments work that affect mind and brain.