Patients in chronic pain have always had it rougher than patients with a disability you can see. If we see a patient who has lost a limb or can’t walk due to paralysis, we all understand that these patients are disabled. However, a patient who just has chronic pain has an invisible disability. That is, until about a decade ago when our brain-imaging technologies became sophisticated enough to show distinct differences between you and I and a patient with chronic severe pain. This morning I’ll review a paper that demonstrates that even in chronic-pain disorders we thought were more limited to a body area (like chronic pelvic pain), there are still big changes in the wiring of the brain.
Chronic Pain and the Nervous System
It’s our nervous system that registers when we are in pain. An injury occurs that stimulates our pain-sensing neurons, and the neurons send signals to the brain to let us know we are in pain. The first thing that is important to understand is that pain is absolutely real (read my post “Return of the Biopsychosocialists…”), and we already know that the brain does experience actual physical changes with chronic pain. Interestingly, even our pleasure-sensing neurons, as one study shows, can change their functionality and transmit pain signals to the brain when there is chronic pain. So even an otherwise pleasurable touch can be registered as pain.
Widespread pain, or pain distributed throughout the body, can be a bit more complex to diagnose and treat, but one thing we do know, and that we’ll see in the study below, is that the brain is a key player. In our new study this morning, patients with chronic pelvic pain were compared to subjects with fibromyalgia, so it’s important to understand these diagnoses before we move on to the study.
Urological chronic pelvic pain syndrome is also known as “pelvic pain” or interstitial cystitis includes symptoms such as pain with urination (dysuria) and chronic pain in the pelvic region. These patients often have difficulty with frequent urination as well, making a car trip a nightmare.
Fibromyalgia is the classic paradigm of widespread pain disorders. Symptoms include generalized and chronic muscle pain, fatigue, anxiety or depression, sleep problems, brain fog, and much more. Fibromyalgia is pain everywhere.
New Study Compares Chronic Pelvic Pain to Fibromyalgia
The new study consisted of subjects in three groups: those diagnosed with chronic pelvic pain, those diagnosed with fibromyalgia, and a healthy control group. While pain location and intensity was recorded, more importantly, sophisticated brain imaging that can measure activity was also used. This is called a functional MRI (fMRI).
The interesting finding in the chronic pelvic pain patients is that they didn’t just report localized pain or pelvic pain, some also reported a widespread pain. Even stranger, compared to the fibromyalgia group who is supposed to have widespread pain, the chronic widespread pain was the same! So why are patients with chronic pelvic pain experiencing generalized chronic pain symptoms identical to fibromyalgia patients?
The study suggests the explanation may lie in the brain. The fMRIs of the chronic pelvic pain subjects who reported widespread pain and the fibromyalgia subjects showed the same results in both groups: an increase in the volume of gray matter in the brain as well as changes in the parts of the brain that transmit and interpret pain signals (functional connectivity of sensorimotor and insular cortices). The control group didn’t show any of these changes.
We’ve Always Recognized That Chronic Pelvic Pain Involves the Sacral Nerves
Many years ago, I began to notice two important things. One was that many of my patients who had chronic low back pain also had frequent and painful urination. The second was that when we performed an epidural injection to treat painful nerves, this would often go away for a while. While I had many of these patients worked up by urology, the answer always came back the same: it was likely that their nerves were affecting their bladder. The same thing would happen in patients who had chronic pelvic pain. Many of those patients could be helped by a caudal epidural or injections to tighten lax sacroiliac joint ligaments that were irritating sacral nerves. Hence, these pelvic pain syndromes were merely a function of irritated sacral nerves. This came as a surprise to many patients, who would often undergo expensive and extensive chronic pelvic pain programs, which didn’t seem to help them very much.
The upshot? First, it’s amazing that we can now use technologies like fMRI to measure pain and how it impacts the brain. To every physician in the ’90s who thought that chronic pain patients were faking their illness for secondary gain, I hope you eat some serious humble pie about how wrong and cocky you really were! Second, the fact that chronic pelvic pain can go widespread and that involves the brain isn’t surprising. We’ve been treating these patients for years as a sacral-nerve problem, so it’s not surprising that chronic, untreated sacral-nerve problems can change how the brain processes pain!