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HPA Axis
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Chronic Fatigue Syndrome
Chronic Pain
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Irritable Bowel Syndrome
Chronic Lyme Disease
Recovery from CFS

Chronic Pain Disorders

Emotional and psychological factors appear to be important factors in causing and perpetuating the pain in disorders such as fibromyalgia, chronic regional pain syndrome, sciatica, chronic lower back pain and repetitive strain injury. This doesn't mean the pain is imaginary or minor, or that the person is "nuts".

Almost everyone experiences psychosomatic pain at some point in their lives due to stress. Generally it is experienced as back/neck pain and headache, due to work stress.

Many cases of lower back pain are diagnosed as being due to a herniated disc or similar structural abnormality. However studies of people over 60 who are not experiencing any pain show that over 50% of them have an abnormality that shows up on an MRI. Clinical trials show that surgery has no statistically significant benefit over "usual care" (education, physical therapy and NSAIDs) for back pain when there is disc herniation. This suggests that herniated discs are a normal part of aging and do not necessarily cause back pain.

What causes chronic pain?

Chronic pain appears to be either an "echo" of previous pain, an amplificiation of minor pain/discomfort, or sometimes completely new pain that is generated by the brain. The pain is completely real, in that the somatosensory cortex (the pain processing centre in the brain) is activated. Sometimes the pain is felt only during exercise, sometimes skin becomes over-sensitive and produces pain sensations when touched, and in some cases the pain is present all the time.

According to Professor John Sarno the main causes of chronic pain are unresolved emotional conflicts, repressed emotions, and mental stress. Sarno calls this condition Tension Myositis Syndrome. Patients tend to be perfectionists who put others needs before their own, and tend to keep emotions hidden in order to avoid conflict.

The science of chronic pain

Chronic pain may be caused by either central sensitization or by painful memories created in the insular cortex and the anterior cingulate cortex.

It has been demonstrated that the spinal cord and brain can be "sensitized" to pain, such that even non-painful stimuli result in pain. This can be demonstrated in the lab. It appears that changes to neurons in the spinal cord cause this sensitization, and there is evidence that it is a factor in fibromyalgia and other chronic pain conditions.

The insular cortex (or just "insula") is a very old part of the brain (in evolutionary terms), and is responsible for many functions including motor control, self-awareness, empathy, pain and emotions. The insula appears to take sensory and emotional information in order to create an emotional context for sensory experience. Fibromyalgia patients have been shown to have hyperactivation in the insular cortex, as well as the somatosensory cortex and the anterior cingulate cortex.

The anterior cingulate cortex has a number of functions including determining the emotional response to pain, perceptions of the unpleasantness of pain, as well as being involved in processing conflicts and errors, and may be the base of self-confidence.

The reason for chronic pain might be the brain's way of trying to get the person to do something about an unresolved emotional conflict. The parts of the brain that appear to be involved in chronic pain have limited connections to the outer neocortex (the "new" brain), so producing pain may be the only way of communicating the need to resolve the conflict. Emotional/social pain and physical pain are processed by the brain in similar ways, and emotional factors can exacerbate physical pain. The pain itself feels the same, no matter what the cause.

Chronic pain may also be a protection mechanism, designed to protect the body from damage after an accident. The brain generates sensations of weakness, fatigue and pain after an injury, in order to protect from further injury. The pain and weakness sensations are generated in the brain, based on input from pain receptors as well as memory and emotions. The brain generates an "emotional memory" of the pain, which persists as long as there is still pain generated by the injury. In some cases, however, the "pain memory" persists and generates the sensation of pain even after the injury has healed.

Classical conditioning may contribute to chronic pain, due to the expectation of pain when performing a particular activity. Experiments in human subjects have shown that the brain regions associated with pain processing can be conditioned to activate whenever a tone is heard. This is thought to prepare the brain for the task of processing the pain.

Prefrontal cortex

The prefrontal cortex seems to be an important modulator of pain. Experiments in both animals and humans have found that the prefrontal cortex (PFC) has an important role in pain processing. The PFC has many connections to pain processing parts of the brain, including the hippocampus (which is important for learning), the amygdala (emotions), the somatosensory cortex (the primary pain processing area), as well as other brain regions.

The PFC has roles in both downregulating pain, and in upregulating and maintaining pain. Studies into the placebo effect show that the PFC is activated during placebo pain relief.

Patients with chronic pain tend to have less grey matter in the PFC, and this is reversed after treatment. Similar reductions in grey matter in the PFC have been found in CFS.

There is a strong link between depression and pain, and studies in both animals and humans have shown that this link appears to happen in the PFC. Symptoms of depression are strongly correlated with higher activation of pain processing areas in the brain.

The dopamine/reward pathway

Dopamine release in the PFC is an important part of the brain's reward circuitry. Studies in rats have shown that dopamine release in the PFC significantly reduces pain responses. In humans, dopamine receptors in the PFC have been shown to be correlated to the efficacy of placebo pain relief. Pleasurable stimuli, including reward, have been shown to inhibit pain.

Myofascial pain

There may also be actual physical pain generated due to muscle tension as a result of anxiety and worry about the pain.

Myofascial pain may be one of the mechanisms behind chronic pain. Myofascial pain refers to muscle pain which is associated with taut bands of hypercontracted muscles which are painful when touched or during exercise. In some cases the pain can be spontaneous (referred to as "active myofascial pain"). Myofascial pain is thought to affect 85% of the population at some point during their lives, and is thought to underlie the pain in fibromyalgia.

Current research suggests that myofascial pain is caused by psychological stress. Sympathetic nervous system activation results in persistent muscle contraction, which results in pain due to hypoxia (lack of oxygen in the local muscle tissue) and acid buildup in the muscle.

All in the head, or in the muscles?

As summarised above, the science is unclear about whether chronic pain is produced entirely in the brain, in the brain and the spinal cord, or in the muscles themselves. However in all the models of chronic pain it appears that psychological stress and emotional factors are important in causing persistence of the pain, and this is also borne out by clinical experience (John Sarno's books and research provide a good overview of the clinical effectiveness of treating chronic pain by resolving emotional conflicts). While the actual mechanism behind the pain is interesting on a scientific and intellectual level, it may not actually be that important in curing the pain.

In some cases the psychological factors causing the pain may be ongoing issues (e.g. bad relationship, stress at work). However in many cases the chronic pain itself may be the psychological perpetuating factor, in a negative feedback loop. This is similar to chronic fatigue syndrome, where the symptoms of the illness itself appears to be a factor in perpetuating the illness. Most clinicians who are familiar with chronic pain recommend that slowly building up to a normal life is an important step in recovery (rather than giving up all activities and staying in the house, which likely contributes to the negative psychological outlook).

What is the cure?

Treatment for chronic pain typically involves:

References and resources Central Sensitization in Chronic Pain

Curable Health blog — the science of chronic pain, and resources for dealing with it

Wikipedia page on sensitization

Wikipedia page on fibromyalgia

Wikipedia page on the insular cortex

Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation

Surgical vs Nonoperative Treatment for Lumbar Disk Herniation

Mechanisms of Myofascial Pain

A Small Part of the Brain, and Its Profound Effects

Mapping pain in the brain

Healing back pain, the mindbody prescription, by Dr. John Sarno

New developments in the understanding and management of persistent pain - Herta Flor PhD, Curr Opin Psychiatry. 2012;25(2):109-113.

Classical conditioning of pain responses. International journal of neuroscience, 78(1-2), 21-32

Role of the Prefrontal Cortex in Pain Processing

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DISCLAIMER: is an educational resource for chronic fatigue syndrome (CFS), myalgic encephalomyelitis (ME), burnout and related disorders, and is not giving medical advice. Seek advice from a medical practitioner before making any changes to your life, or if you experience worsening symptoms. CFS is a diagnosis of exclusion, so it is important to rule out other causes for illness.