Chronic pain conditions often occur together in the same person, which means that they may have similar underlying causes.
Image Reference: Chronic Pain Research Alliance. (2018). Chronic Overlapping Pain Conditions. Patient Guide. Retrieved from http://www.chronicpainresearch.org/public/CPRA_Patient_Guide.pdf
There is substantial evidence that endometriosis is estrogen dependent and seems to be related to a dysregulated immune response and chronic inflammation (1). Familial association suggests a genetic predisposition as well. But these factors do not result in the same presentation of symptoms or the same experience of symptoms from one person to another. For example, two people with confirmed severe endometriosis can present very differently. One person may have pain on most days of the month and suffer from many different types of pain, depression, migraines, and bladder or bowel troubles, while the other person may have bad period pain but is otherwise completely well.
Why the disconnect between disease stage, progression, and symptoms? No one knows exactly how endometriosis causes pain. But chronic pain conditions often occur together in the same person. This suggests that chronic overlapping pain conditions may have common underlying disease mechanisms.
You may recall when your only problem was period pain. Then, something happened. Maybe it was a really bad period, a stressful situation, a traumatic injury, a bad relationship, a new job, the birth of your baby, chronic stress (or for no reason). Now, everything feels more sensitive or more painful. New symptoms may have started as well, like a swollen belly, known as “endo belly”.
This is called central sensitization and is thought to facilitate the development of chronic pain. Basically, your nervous system received a threatening signal and dialed up the sensitivity meter so it could pay close attention. The brain reads the signal, perceives the need for a protective response, and reacts in a way that creates pain.
The function of acute pain is to protect us from danger. But what happens when there is no longer a threat? In some cases, instead of settling down once the original injury has healed, the nerves change their structure.
Central sensitivity is associated with long-term changes in pain pathway structures. This is known as neuroplasticity; it can affect the way a nerve sends signals, and the way the nervous system perceives those signals. Basically, nerves become irritated, injured or sensitized, and change their structure. As a result, the way the nervous system perceives painful impulses changes. The brain now misinterprets normal, non-harmful signals from the body as dangerous. There may also be increased sensitivity to a normally painful stimulus (touch, pressure, pinprick, cold, and heat), and wind-up pain (pain felt over a larger area than usual when it is severe compared to when it is mild).
Can endometriosis cause central sensitization?
Yes, through the formation of new blood vessels and nerves as the lesions grow. And because endometriosis is an inflammatory condition. Inflammation in the body can sensitize the nervous system (2).
This can become a vicious cycle. The nervous system has become highly vigilant and sensitized. Normal, non-harmful signals from the body cause pain. New, painful conditions develop in many different systems of the body. Negative emotions, stress, illness perceptions, pain cognitions and pain behaviour contribute to, or trigger, persistent pain. All of this new information feeds back to the brain, keeping the nervous system from calming down, and reinforcing the process.
Even in the absence of tissue injury or inflammation, people with central sensitization can feel pain. The body region in which it arises may be less relevant; neuroplastic changes increase pain transmission all over. That is why you may develop other pains. Your pain is real. It’s in your brain, but it is not in your head.
Image Reference: Todd Hargrove (2019). Playing With Movement: How to Explore the Many Dimensions of Physical Health and Performance. Seattle WA: Better Movement. 254.
If you look at the figure above, you can see that “inputs” or incoming signals that your brain receives from nerve endings are interpreted in the context of other information from many different brain areas (ie those related to sensations, memories, emotions, thoughts, perceptions, fears, goals etc). There is no specific pain centre in the brain. The brain (neuromatrix) takes in all of the available information and then decides if pain is needed for protection. Pain is a protective response, like an alarm system. Pain responses or “outputs” may include feelings like pain or movements like limping. Even stress is a protective response that involves changes to the immune system and endocrine system, which help mobilize resources to deal with the threat (real or perceived).
These “outputs” become new “inputs” into the system, and the process repeats in a slightly altered form. Perception is a powerful tool. Pain can be activated by the unconscious perception of threat, whether or not a real threat exists. If you perceive yourself to be a victim – weak, incapable, under attack, broken, fragile, damaged, vulnerable to threats – then your brain will respond in a way necessary for protection. The nervous system is always at work, reading and interpreting evidence about our environment, in the context of our past and present state. But it’s also adaptive, always changing its level of sensitivity.
Pain is not located in any particular area but emerges from the complex interactions of many different parts.
How will you break out of your pain cycle? Sensitized nervous systems can slowly shift back to a normal level of pain sensitivity, especially when they are supported with rest, recovery, sleep, nutrition, stress management, positive mindset, support, and healthy forms of challenge (ie good stressors like slow and novel movements). Think of this approach as a reset to baseline sensitivity levels.
Your first step may be finding a supportive healthcare provider who will help you understand the connections between your symptoms and your chronic stress, dietary choices, sleep patterns, movement and exercise habits, environmental exposures, mindset, and personal beliefs.
A multidisciplinary holistic approach is gold standard best practice for persistent pelvic pain. A Naturopathic Doctor is one of several health care providers that can be involved in your treatment.
When looking at the bigger picture of pain, you can now appreciate that there are many factors that work together to cause pain and affect the body as a whole. As a Naturopathic doctor, I am uniquely trained to view the body as one integrated system. I take the time needed to document and fully understand the constellation of symptoms (even the non-specific symptoms) an individual experiences and explicitly discuss it in the context of their disease, along with their needs and health goals.
There is no single treatment that adequately addresses every symptom in every person; hence the need for patient-centered care and a multidisciplinary holistic approach. My toolbox is varied and equipped to address biological, psychological, and socio-environmental factors. Lifestyle interventions, mind-body practices, pain education, nutrition, nutraceuticals, botanicals, and supplements can help break your pain cycle for best care and improved quality of life.
1. Romm Aviva Jill. (2018). Botanical Medicine for Women’s Health, 2nd Ed.
3. Evans, S. & Bush, D. Endometriosis and Pelvic Pain. 3rd Ed. 2016.