I view patients who come to me with pelvic pain as a puzzle of sorts. Something is causing pain, and it’s my job to figure out what, and solve the puzzle. After specializing in endometriosis and pelvic pain for over 10 years now, most of the time the puzzle is easily solved, but some patients are very challenging and can take some time to figure out what is truly the root cause of their pain.
The quality of pain (sharp, dull, achy, twisting, pulling, electric shock, etc) as well as the location and timing are important clues in determining the causes of pain. The most common sources of pelvic pain are endometriosis, pelvic floor muscle spasm, interstitial cystitis, uterine pain (either from adenomyosis, fibroids, or even a “normal” uterus), orthopedic issues (hip impingement and labral tears, disc disease, SI joint dysfunction), pelvic congestion (varicose pelvic veins) and nerve pain. Endometriosis tends to be cyclical pain, but as it progresses can become constant. Levator spasm tends to worsen while sitting, and hip pain tends to be more associated with exercise and physical activity. Pelvic congestion patients tend to feel fine when they first wake up, and they have an achy heavy pain that worsens the longer they stay on their feet.
Generally, there is one main underlying condition that causes most of the symptoms the person is having, and correcting that one thing often will relieve all the symptoms. Endometriosis is the most frequent root cause of pelvic pain, and removing the disease is the most effective treatment for endometriosis. However, there are usually secondary causes of pain that occur in response to the primary pain stimulus. This is why many women with endometriosis will also have pain from pelvic floor muscle spasm and Interstitial Cystitis. In my experience, about half of women with endo will have most or all of their pain resolve after excision, and the other half will have some relief, usually of their sharp endo specific pain, but will have persistance of their pelvic floor or bladder pain. In these cases, we begin to treat the IC, and facilitate referrals to physical therapy, which is very successful at treating the muscle spasm.
Chronic pain is like an onion- there are layers upon layers of pain generators, most in response to the primary underlying source. For patients with endo, removing all of the disease is I believe the most important first step. This will decrease the amount of “nociceptive stimuli” (pain signals prior to being perceived as pain in the brain) coming into the central nervous system. We don’t totally understand pain processing yet- it is exciting but still in its infancy. There seems to be a correllation between duration and severity of pain and the likelihood of developing “central sensitization”- essentially where the brain overexaggerates the perception of pain, such that even an injury that should result in minimal pain (ie stubbing your toe) causes severe pain in these sensitized individuals. Similarly, the more pain stimuli we can remove (ie by excising endometriosis), the better the chances that the sensitization will reverse itself. Unfortunately, this often is a slow process that happens over several years.
The rationale for addressing the endometriosis before the bladder and pelvic floor is twofold- one is the central sensitization mentioned above, the other is a direct stimulation of pelvic floor muscle spasm by the endo. I often see patients with relatively localized spasm in only one section of the pelvic floor, and when we get to surgery they have a large mass of endometriosis sitting right over that muscle, irritating it and causing it to reflexively contract. Or, there can be endo in close proximity to a nerve, usually the obturator nerve, rarely the sciatic, and in these cases there is usually immediate relief of the nerve pain postop. Once the endometriosis is removed, then about half the time the muscle spasm resolves on its own, and the rest of the time physical therapy is much more effective than preop to teach patients how to relax their pelvic floor muscles.
Interstitial cystitis (IC) is related to both the endo and the pelvic floor spasm. The latter is easier to understand – the pelvic floor needs to relax as the first step in the micturition (voiding) process. When this doesn’t happen, the bladder can’t empty completely and this leads to more frequent voiding, increased chance of UTIs, and usually a more irritable bladder. The pain aspect of IC is most likely caused by a phenomenon called “neurogenic inflammation”. The best explanation I can give is as follows: Something in the abdomen and pelvis causes chronic pain. This is most frequently endometriosis, but it can be adenomyosis, diverticulitis, ulcerative colitis or crohns, or even recurring culture positive UTIs. This chronic pain sends nociceptive signals up the peripheral nerves to the spinal cord where they overwhelm the synapses to send the signals to the brain. What happens then is almost a “backstop” effect where instead of going upwards to the brain, the nerve signals travel backwards down a sensory nerve into the bladder. For you science nerds this is called “antidromic transmission”. When this nerve impulse gets to the bladder, the sensory nerve ending doesn’t know what to do with it as it usually sends signals, not receives them. This backwards signal then causes the release of all sorts of inflammatory chemicals the best known of which is histamine, but also nerve growth factor which- guess what- grows more nerve endings. This neurogenic inflammation now can cause the leakiness of the lining of the bladder which then allows irritants in the urine, specifically potassium, to contact the urothelial cells that line the bladder and have sensory nerves that are stimulated by the urine, causing pain with a full bladder, urgency, frequency, and what we know as IC or PBS (Painful Bladder Syndrome).
Again, as with the pelvic floor, in my experience IC is easier to treat and gain control of when the endometriosis has been removed. Some bladder symptoms will resolve spontaneously after excision, some need temporary postop treatment such as bladder instillations, physical therapy, and oral medications, and some need lifelong attention, such as avoiding dietary irritants. IC is unfortunately not a disease that is curable, but rather a syndrome that can be managed such that you are in control of your bladder, not the other way around.
Many physicians including some prominent gynecologists don’t believe in excision of endometriosis because “you can’t fix everyone”. There is confusion between amount of pain and amount of disease, and the two don’t always correlate either preop or postop. Excision of endometriosis has been shown in several studies to have a 56% surgically proven cure rate – ie these are patients who underwent excision by an expert endometriosis surgeon, then had another surgery later and did not have any endometriosis found. In Redwine’s study about half of his patients had a second surgery either for pain or other gynecologic reasons, and the other half felt fine without pain and didn’t require another surgery. Taking these two groups together results in a 19% chance of persistence or recurrence of endometriosis after excision. This doesn’t mean, however, that only 19% of patients will have persistent pain. The unfortunate reality of chronic pain and central sensitization is that some patients (generally the same ones who have fibromyalgia and other symptoms of a hypersensitive pain processing system) will have persistent pain which feels the same as it did prior to surgery and not related to the pelvic floor, bladder, or other causes. Fortunately, this affects less than 5% of patients in my experience, and they tend to be younger patients with early stage disease. This brings up the idea promoted by some doctors that we shouldn’t even operate on these younger girls, rather just treat their anxiety and hope their pain goes away. I believe they are missing the point that most of even these younger, early stage patients do have some degree of pain relief, and as of now we have no accurate screening tools to tell us who would benefit from surgery and who won’t.
Most people have heard of “phantom limb pain”- where amputees will feel pain in their arm or leg that they no longer have. I think there is a similar phenomenon at play in the pelvis where the nerves that have been chronically stimulated over a long duration continue to fire even though the stimulus is gone. This is called “Complex Regional Pain Syndrome” (CRPS) and can happen in any part of the body. Traumatic experiences, especially in childhood and early adulthood, can cause anxiety that will amplify the perception of pain. Essentially the way this works is that when the nociceptive impulses reach the midbrain, it reaches out to the sensory cortexes to ask “is everything ok? Vision cortex, are you seeing anything dangerous? Auditory cortex, are you hearing anything dangerous?” When the answer is “No, everything’s fine”, then the midbrain thinks it’s a false alarm and tells the spinal cord to suppress the nerve traffic. When the answer is “I’m nervous- I think there might be danger lurking”, then the midbrain thinks this is a real emergency, and heightens the sensation of pain to warn the human that something bad is happening. Originally, thousands of years ago, this was a protective mechanism that was very beneficial in preserving the species. It still is helpful in the case of acute pain, like if you get your hand too close to the flame of your gas stove like I did last week trying to roast peppers for my salsa! However, it has become a factor in perpetuating chronic pain, and converting acute pain into chronic pain. Based on this understanding of pain processing, a technique called “Cognitive Behavioral Therapy” (CBT) has been shown to be very beneficial to patients with chronic pain and anxiety. It essentially teaches people how to get control of their anxious thoughts, and by ratcheting back the fear, it can also help with the pain.
Many patients have a hard time understanding the ideas in the previous 2 paragraphs about central sensitization and CRPS. They have had to endure years of inappropriate treatment by doctors who don’t understand pelvic pain, many have been told they’re crazy, drug seeking, or worse. They have been told their pain is “all in your head” when the commonly performed and ineffective ablation of endometriosis has failed, and have been kicked out of practices when they refuse Lupron. Upon hearing that pain is processed in the brain, and that there are many psychological factors that can upregulate the perception of pain, they think that I too am telling them the same thing. While it is true that “all pain is (processed and perceived) in your head”, it’s not at all the same thing. I believe that ALL SOURCES OF PAIN NEED TO BE ADDRESSED FOR OPTIMAL OUTCOMES, not just those that we can treat by surgery and medication, but also the hypersensitive pain processing system which at this point in time, is best treated by CBT. Just as it is inappropriate to dismiss things that can’t be seen by imaging as real sources of pain (ie endometriosis, IC, PFD), I believe it is just as inappropriate to only address the somatic causes of pain and ignore the brain. There’s a phrase that has been promoted recently- “Treat the whole person”. For patients with chronic pelvic pain, the bio-psycho-social connections are very important to recognize and we need to be just as concerned with the “psycho-social” part of the person as we are with the “bio”. Unfortunately these resources are very hard to find just as mental health services for just about any reason are sparse. But I digress…..
In summary, chronic pain from any cause is quite complicated, and is something most physicians learn little or nothing in school. For those of us who went to med school 20 years ago, what we learned then is mostly outdated information now. The real problem is that we are behind in understanding the basic neurophysiology of pain, and are only now just starting to understand how the brain works. Understanding the basic science of pain is fundamental to being able to assess how best to treat our patients with chronic pain.