Associate Clinical Professor of Reproductive Biology
Case Western Reserve University
Cleveland, Ohio
tij@att.net
"Thus the task is, not so much to see what no one has seen yet,
But to think what nobody has thought yet,
About what everybody sees."
-Schopenhauer
Professionals treating women suffering from chronic pelvic pain are acutely aware that despite their best efforts some of the patients do not respond to standard therapeutic modalities. Common threads in their history include multiple surgeries, some of them with temporary improvement of pain symptoms, pathology out of proportion to experienced pain (opinion of the surgeon), or no visible pathology [1],[2], pain is aggravated by stress, pain is a daily occurrence. Other frequent findings include history of sexual or physical abuse [3, 4] as a child or adult, traumatic memories, and co-morbidities[5],[6] including: vulvar vestibulitis, fibromyalgia, interstitial cystitis, irritable bowel syndrome [7], chronic allergies, etc.
Laparoscopy under general anesthesia may be deceptive, rather then helpful. When there is lack of significant pathology, we will label minimal inactive endometriosis, minor pelvic adhesions and dilatated pelvic veins as causes of chronic pelvic pain, even that during laparoscopic pain mapping under conscious sedation similar lesions in other patients would not be associated with pain. On the other hand during pain mapping we will find that entire pelvis reproduces pain [8] including pain perception on the opposite side to the side examined [9]. One of the most common findings in this group of patients is that many times despite failing to discover a definite source of pain the appearance of the pelvis suggests that this patient has chronic pain – entire pelvis is congested.
Looking for similar conditions in the other fields of medicine, one is struck by similarities between Chronic Pelvic Pain and Complex Regional Pain Syndromes (CRPS) I and II. Causalgia (from Greek burning pain) presently reclassified as CRPS II, was first defined by S. Weir Mitchell, Civil War physician. He described development of burning pain in the distal extremity following partial, even minor nerve injury under the high stress conditions of the battlefield zone. In addition to spontaneous pain, patients reported sensitivity to light touch and triggering of the pain by strong emotions, loud noise, and movement of the extremity. The physical signs included swelling and mottling of the skin, smoothness and loss of skin appendages and on occasion arthritis [10]. In 1916 Leriche reported dramatic relief of symptoms following sympathectomy. The reports of causalgia were usually limited to the time of war: Civil War, WWI, WWII and Vietnam War. Between the wars, concept of sympathetically affected pain was applied to patients without detectable nerve injury and Evans named it Reflex Sympathetic Dystrophy (RSD). The RSD was first described in 1902 by Sudeck, it was characterized by asymmetrical pain and swelling of the distal extremity following a fracture, minor soft tissue trauma, low-grade infection, frostbite, burns, stroke or myocardial infarction. In addition to pain and swelling, autonomic symptoms included: altered skin color and temperature, and altered sweat production. The pain is exacerbated by keeping extremity in a dependent position, movement and pressure on the joints; again significant pain relief can be accomplished by sympathetic block.
At first glance it would be hard to compare visceral chronic pelvic pain and extremity pain in CRPS, but upon closer examination there are several similarities. Some of the autonomic symptoms used to diagnose CRPS may not be applicable to Chronic Pelvic Pain (CPP): CRPS – asymmetry of blood flow and temperature between left and right extremity, CPP – Pelvis is in the middle; difference in sweat production between left and right extremity in CRPS can not be used in CPP. On the other hand similarities include: Increased response to pain in patients with CPP (ovulation may bring the patient to the ER and initiate new cycle of exacerbated pain). Relatively minor stimuli will maintain the pain: minimal endometriosis, adhesions, occult hernias are most likely triggers rather than the sole cause of the pain. Patients with CPP complain that the pain is worse while standing, walking and prolonged sitting, or in other words, when the pelvis is in a dependent position. Laparoscopic findings include: hyperalgesia in the pelvis during pain mapping under conscious sedation[8], congestion of the vessels in the pelvis, and more than 50% improvement of pain after transection of superior hypogastric plexus (part of autonomic nervous system)[11].
It is not about anatomy, it is about function. The autonomic nervous system is the operating system of our body. A good analogy would be a computer, where autonomic system is motherboard (hardware) and Windows operating system (software) combined. It runs in the background without making us aware of its function, it keeps us alive. It runs programs (routines), it has predetermined program for every function of our body [12]. It has programs to maintain our blood pressure, breathing, bowel movement, hormone production, inflammatory response, erection, temperature control, etc. These programs allow us to function and survive in our changing environment (within certain limits). There are limitations however; our autonomic nervous system does not have a program to supply us with oxygen under water. If we are drowning consciously we will be able to override the urge (program) to take the breath, but at some point we will be forced to take a breath to fill the lungs, unfortunately we lack the program to extract oxygen from water (for our autonomic nervous system underwater environment does not exist). Our autonomic system is not very smart, but it is adaptive. Given sufficient amount of time and data our autonomic nervous system can develop new routines (occasionally quite useless), like in the case of Pavlov’s dog. The possibility exists that in the case of RSD, the autonomic nervous system has developed a maladaptive routine, which has pain as its integral part, Sympathetically Maintained Pain (SMP).
The role of acute pain is quite straightforward; the pain is there to inform us about an injury to our body (treat to homeostatic integrity of the tissue). At this stage nociceptors (free nerve endings) within the tissue are activated by painful stimuli. Afferent nerve fibers transmit the message to the dorsal horn of the spinal cord. In the spinal cord the pain message undergoes initial processing, causing the signal to be increased or diminished before it is transmitted to the brain structures, where it is recognized as pain. In the case of the acute pain, autonomic nervous system is usually involved only marginally. It increases blood flow through the injured area, or runs routines to respond to an invading infection. It may also run other predetermined routines that we are unable to detect due to its seamless operation.
Chronic pain is quite a different condition. First, the definition of chronic pain is not very clear, “If pain persists beyond usual course of an acute injury or disease, or recurs every few months or years, it is regarded as chronic”. Chronic pain does not serve the same purpose as acute, because it may happen without any apparent tissue injury or even after removal of the tissue (phantom leg after amputation). In chronic pain, spinal modulation is usually geared toward the hypersensitization of nerve cells through a phenomenon called “windup”[13],[14], when an environment is created in which even small impulses are registered and amplified, leading to the perception, that physiologic conditions like distention of the bowels or bladder, or ovulation are painful. The role of the autonomic nervous system in the chronic pain appears to be much greater.
Sympathetically Maintained Pain (SMP)[15] occurs in a number of chronic pain conditions within CRPS system. In testing involving patients with CRPS II spontaneous pain and hypersensitivity to cold and touch in the affected hand can be alleviated by thoracic sympathectomy, or by the block of the stellate ganglion and than rekindled by subcutaneous injection of epinephrine, indicating sympathetic contribution to the pain.
The role of the autonomic nervous system is to maintain and to adapt our body to the environment. If the new stimulus (including pain stimulus) is maintained for a sufficiently long time it becomes part of the environment within which the autonomic nervous system functions. For the autonomic nervous system this stimulus (pain) is neither negative or positive, it is just a part of the environment. The autonomic nervous system does not make judgments, it just runs routines, the judgments are made by central controls. If the central controls are constantly distracted by other issues, such as dealing with stress, significant past emotional or physical traumas like in post traumatic stress disorder, the central controls will not prevent pain from being incorporated into new maladaptive programs. After this point removal of the initial source of pain may not alleviate the pain permanently, as the system will look for new sources of pain to plug it into this program, creating Sympathetically Maintained Pain.
We assessed function of the autonomic nervous system in patients with chronic pelvic pain and healthy controls without a history of pelvic pain, we found significant differences in function of autonomic nervous system between the study and the control group.
Our data suggests that at least some of the patients with chronic pelvic pain suffer from complex neurological condition, which involves a dysfunction of the autonomic nervous system. One would also include in this spectrum of chronic pelvic pain, interstitial cystitis, and irritable bowel syndrome (mostly constipation predominant).
The fact that autonomic nervous system serves as the vast network of bridges between the central nervous system (including cognition and emotions), external environment and the rest of our body [18-23], makes comprehensive treatment including stress management and psychotherapy essential.
Several animal studies of fear processing suggest that there is a possibility of central nervous system processing that does not involve neocortex (conscious thinking part of the brain) and than, the processing is done at the thalamus [24-25] (mid brain) activating fight/flight/freeze reaction without conscious control. Thus the patients who suffered severe emotional trauma as children or adults (i.e. Posttraumatic Stress Disorder) and try to describe past traumatic events, find themselves unable to talk about them, “they have no words to describe them”. At the time of their initial traumatic experience (they were “scared to death”) the processing in the brain skipped the conscious part and the experience was imprinted as a visceral fear. This kind of processing route can possibly imprint itself as a preferred way of managing stressful events in the future and cause continuous hyper activation of the autonomic nervous system. For that reason, psychotherapy is used to address stress management, develop new coping skills and promote new stress processing routes in the brain is essential part of the treatment of the patients with chronic pelvic pain.
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