Is Chronic Pelvic Pain (CPP) a form of CRPS?

Chronic pelvic pain (CPP) is persistent and often disabling pain experienced by women (men are rarely affected) below the level of the belly button and between the hips. The condition is common, thought to affect as many as one in six women in the UK.

Causes of Pelvic Pain

Pelvic pain often comes on suddenly. There are numerous causes, including, but not limited to:

• an ovarian cyst;
• acute pelvic inflammatory disease;
• peritonitis;
• a urinary tract infection;
• chlamydia;
• appendicitis;
• endometriosis;
• constipation;
• irritable bowel syndrome (IBS).

When it first develops, pelvic pain is referred to as acute, but if it lasts for more than six months, whether continuously or intermittently, it is known as chronic pelvic pain.

For many years there has been a belief in some quarters that CPP may be a form of complex regional pain syndrome (CRPS). Once the initial cause of the pain has resolved or been treated, patients suffering from CPP report allodynia and hyperaesthesia. But the inability of CPP sufferers to otherwise satisfy the Budapest Criteria has proved a significant hurdle for broader acceptance of this theory among the medical community.

Now, however, two pain physicians in the US have published a paper, based upon their clinical experience, in which they put forward a case for treating CPP in a similar manner to CRPS.

The authors argue that as the pelvic region has a very different anatomy to the extremities, particularly concerning the sympathetic nervous system, it cannot be expected that CPP will present in the same manner. As such, rather than focusing upon the Budapest Criteria, they say “clinicians should be drawing upon physiologic similarities where the pelvic region is responding in a parallel fashion. There are many parallels between the characterizations and symptoms of chronic pelvic pain (CPP) and complex regional pain syndrome (CRPS), as well as the response to treatment.”

Parallel Symptoms

Allodynia

Although the stimuli encountered by our extremities are different from those of the pelvic region, people suffering CPP and CRPS both present with allodynia. In CRPS, often extreme pain is triggered by what would usually be considered an innocuous stimulus, such as gently touching the skin. In CPP, painful stimuli that should not otherwise provoke pain include such things as sitting, wearing underwear, urinating, and defecating.

The cause of allodynia is thought to be peripheral and central sensitisation resulting from nerve damage to the peripheral nervous system. This nerve damage is caused by trauma, surgery or infection and people diagnosed with CPP or CRPS typically report such an event shortly prior to the onset of pain.

Spread

CPRS is known to spread to affect more of the same limb, a different limb, and even other areas of the body. The authors argue that in CPP “there is significant evidence that symptom involvement is not limited to the initial end organ; painful symptoms may occur in nearby organs as well.”

Changes in Blood Flow

Classic signs of CRPS are changes in skin temperature and colour, as well as swelling, due to changes in local blood flow. In their paper, the authors say that “pelvic inflammation is not as readily visible as say, an ankle or hand; however, the changes in blood flow do occur, manifesting in a different form.” They point specifically to the large percentage of patients with CPP diagnosed with pelvic congestion syndrome (PCS) – an increase of blood flow to the pelvic region.

Nerve blocks

For both CPP and CRPS, the authors also highlight the use of, and response to, nerve blocks, although the targets in each case necessarily differ.

Conclusion

Their paper concludes by drawing attention to the greater awareness and recognition of CRPS in recent years, which has served to improve the diagnosis, treatment, and management of the condition. Conversely, despite its many similarities, people with CPP fair far less well, often remaining undiagnosed and without appropriate treatment. They say:

“Both CRPS and CPP are devastating conditions for men and women alike. For decades, those with CRPS were left to suffer agony, largely due to the medical community’s lack of understanding of the condition and inability to recognize it as a legitimate pathology. In recent years, CRPS has gained widespread recognition and may be identified with greater ease. Unfortunately, since CPP is something that cannot be seen with the naked eye or diagnosed during a physical exam, those afflicted may not be afforded the same benefits as those with CRPS in terms of being identified as a pain syndrome that requires the attention of a pain specialist. Patients with CPP may endure their pain for years before finally finding their way to a pain doctor, often being wrongly treated for a urinary tract infection with countless rounds of antibiotics. Worse still is the failure of many pain doctors to pick up on the similarities that exist between CPP and CRPS and to subsequently treat them with the same level of respect and diligence. It may only be in the hands of a pain doctor who specializes in pelvic pain that these patients ultimately find appropriate treatment.”