Researchers are realizing that we have to look beyond the lesions when understanding endometriosis and pain. For women with endometriosis, the severity and location of pain is not correlated with the severity and location of endometriosis lesions - there's clearly more going on. Traditional treatment options like surgery or oral contraceptives target the lesions, but they may not offer permanent relief from pain or endometriosis symptoms.
1. Central Nervous System Sensitization
Sensitization refers to how the body adapts to chronic pain. Pain is supposed to alert the body to an immediate problem so we can react and prevent further harm. For instance, if you accidentally touch a hot stove, the body senses pain and withdraws your hand from danger. However, when pain becomes chronic (longer than six months), it actually begins to re-wire the brain to expect pain. When this happens, sensations that are normal and painless for others can become excruciating for those in chronic pain.
This sensitization begins at branches of the nerves and their nerve endings, called the peripheral nervous system. Nerve endings that sense pain become constantly stimulated by the chronic inflammation. Research even shows that endometriosis lesions can actually begin to grow their own blood supply and nerves, creating even more peripheral nerve pain stimulation. After a while, the constant barrage of pain signals from the peripheral nervous system begins to sensitize or "upregulate" the central nervous system--the manager of the entire nervous system--causing the body to react strongly to every stimulus.
Imagine your nervous system as a giant sound system. First, a few microphones become sensitized or begin to pick up every single little sound even though the other microphones are only picking up loud noises. Then the sound system controls begin to adapt to the microphones and raise the volume of the entire system. Eventually the volume stays high until even small sounds become loud and alarming. This is likely why many people with endometriosis also suffer from fibromyalgia -- a condition where the body experiences widespread pain and fatigue. Effective treatment should include 'resetting' the volume on the nervous system for long-term reduction in pain, not just addressing individual "microphones."
2. Myofascial Pain
Myofascial pain comes from the muscles and connective tissue of the body. These can include muscle spasms, trigger points, or knots in tight muscles. Often these are experienced as extremely tender areas that are quite painful to the touch. These trigger points can occur as a result of overuse of an area, but they can also occur as a result of sensations felt by "viscera", or organs.
The nervous system does not allocate many nerve pathways and typically shares nerve pathways with sensory pathways from other areas of the body. That is way you might feel pain from a heart attack in the left shoulder or a kidney infection at the low back. Visceral pain from endometriosis could create trigger points causing pelvic pain, back pain, and abdominal pain. With consistent painful stimuli at these nerve pathways, the body can create a pain reflex that continues even after the endometriosis lesions are removed. In other words, even after surgery, trigger points created from endometriosis will continue unless they are specifically addressed, which likely why many women continue to have pain even after a successful surgery.
The presence of these trigger points can also add to the nervous system sensitization by continuously sending pain signals through the peripheral nerves. One study found that women who presented with myofascial trigger points were more likely to show evidence of nervous system sensitization. Addressing these trigger points may not only reduce pain momentarily but it may help to down-regulate the entire nervous system by reducing painful stimuli.
"Their [myofascial trigger points] deactivation through a targeted intervention may be a critical aspect to reversing central sensitization and improving pain associated with endometriosis." -Aredo et al, 2017
With endometriosis, studies have shown that more than 90% of women have these tender points on the abdomen and 60% in the pelvic floor. Abdominal tender points can cause much of the abdominal pain with endometriosis, while trigger points in the pelvic floor can refer pain throughout the pelvis, low back, abdomen, and thighs. This may be one reason that nearly 75% of women with endometriosis report low back pain, for example.
Treatment Options
So what does this mean for the treatment of endometriosis? First, we have to be willing to look beyond the lesions. While surgical and hormone treatments that focus on these lesions have significant benefits for endometriosis, they often fail to completely or permanently resolve symptoms.
The researchers suggest that a complete pelvic examination be performed on women with (or suspected of) endometriosis, including touching the abdominal wall, perineum and both internal and external pelvic floor muscles. Unfortunately, gynecologists aren't currently trained in these techniques, which are a hallmark of pelvic floor physical therapy.
Physical therapy directly addresses the myofascial source of pain. Studies of other chronic pain conditions like interstitial cystitis and vulvodynia have shown physical therapy to be among the most effective treatment options for patients. Small scale clinical studies and anecdotal evidence both suggest similar efficacy for with endometriosis patients.
This theory also explains the benefits that we've seen with yoga and acupuncture, which have both been shown to reduce endometriosis pain and symptoms, despite having no effect on endo lesions. Both of these treatments have demonstrated the ability to down-regulate or reduce the "volume" of the central nervous system, which could explain how they can help reduce endometriosis pain and other chronic pain. Other practices such as mindfulness may also help to regulate the nervous system response.
Additional Resources
Dr. Nicole Cozean is the founder of PelvicSanity physical therapy, Orange County's premier pelvic floor physical therapy clinic. One of only 270 PTs to be board-certified in the pelvic floor, and the first PT to serve on the ICA Board of Directors, Nicole is the author of the acclaimed and best-selling book The Interstitial Cystitis Solution (2016). She is an adjunct professor at her alma mater, Chapman University. The PelvicSanity blog focuses on presenting practical, positive information to help patients beyond the walls of Nicole's clinic.
Dr. Sharon Thompson is a physical therapist at PelvicSanity physical therapy, Orange County's premier pelvic floor physical therapy clinic. Sharon combines a strong orthopedic background with her skill as a pelvic floor physical therapist. She is vocal advocate for those who suffer from pelvic floor dysfunction or pain, and is especially passionate about spreading hope and awareness about these conditions.