Pelvic Pain and Complex Regional Pain Syndrome
By Robert D. Gerwin, MD
Department of Neurology, Johns Hopkins University, Baltimore,
MD
Pain and Rehabilitation Medicine, Bethesda, MD
Pelvic pain and Complex Regional Pain Syndrome (CRPS) are
both complex issues. The causes of each may be difficult to
ascertain, and their treatment may likewise be difficult.
The question of whether CRPS of the pelvic region exists
is likewise difficult. A review of the medical literature
through PUBMED, the literature research tool of the National
Library of Medicine, failed to find any article in the last
10 years linking or CRPS
to chronic pain in the pelvis. Nevertheless, the issue bears
examination.
Causes of Pelvic Pain
Pelvic pain arises from four separate sources:
1. visceral organs (e.g., bladder, uterus, prostate)
2. pelvic floor muscles (e.g. obturator internus, levator
ani, piriformis)
3. bones and joints
4. nerves (e.g. pudendal nerve)
In practice, it is not always easy to sort these out clinically.
Frequently, if not most often, there are multiple sources
of pain, e.g., a visceral organ, such as the bladder or the
colon, and pelvic floor muscles. Causes of pelvic pain in
women with endometriosis can also be occult, arising from
abdominal muscles with pain referred to intra-abdominal and
intra-pelvic regions.
The cause of CRPS is still poorly understood. (1) Mechanisms
include:
1. central nervous system neuroplastic changes resulting in
hypersensitivity (increased sensitivity to painful stimulation)
and hypoesthesia (loss of feeling)
2. sympathetic nervous system dysregulation
3. nerve injury
4. psychological abnormalities
5. exaggerated regional inflammatory responses leading to
increased pain.
Pelvic CRPS Considerations
The issue of pelvic CRPS arises when pelvic region pain seems
to be out of proportion to identifiable causes of pain. Thus,
extreme or apparently exaggerated pain without an adequate
cause leads one to consider central nervous system changes
that produce allodynia or hyperpathia. One might question
calling such pain CRPS in the absence of skin color or temperature
changes, abnormal sweating, or easily identifiable painful
responses to normal mechanical stimulation such as stroking.
However, there is no question that chronic pelvic hyperpathia
exists. As in other chronic hyperpathic states, this is considered
to represent central nervous system sensitization. Severe
pain, with non-painful or mildly painful responses to stimulation,
by itself does not mean that a person has CRPS. Nevertheless,
when the pain is extreme and there is no other explanation,
the question is legitimate, even if difficult to answer.
Causes of Pelvic Pain
Another way to look at the problem of pelvic pain and CRPS
is to consider the causes of chronic pelvic pain, rather than
to look at the central nervous system changes. Pelvic pain
has often been thought to be a woman's problem, but in fact
it is a problem of both sexes. Chronic prostatitis affects
adult men in all age groups.
The impact of chronic prostatitis with severe symptoms on
the quality of life is as great as that of ischemic heart
disease. (2) Inflammatory chronic pelvic pain has usually
not been found to have an infectious etiology. Hollow organ
distention (of the bladder or the colon) will cause distress
and can become a chronic source of pain. Other common causes
of chronic pelvic pain include non-bacterial prostatitis in
men, interstitial cystitis in men and women, irritable bowel
syndrome in both sexes, so-called pelvic floor tension myalgia
(which is really myofascial pain syndrome of the pelvic region,
and endometriosis. Pudendal nerve entrapment should also be
considered as a cause of pelvic floor pain, manifest by vulvodynia,
proctalgia, painful intercourse, perineal numbness, or general
pelvic pain. Diagnosis is a major issue in chronic pelvic
pain. The relationship between the pelvic organs (viscera)
and the body wall (somatic tissue) must be understood in order
to make a complete diagnosis. Pain in the viscera or internal
organs can be felt in the body wall (viscero-somatic referral).
Pain in the muscles of the lower abdomen and the pelvic/hip
region can be experienced as internal pelvic organ pain (somatic-visceral
referral). These pain relationships occur through connections
in the spinal cord. They are important to understand, because
myofascial trigger points in the lower abdominal muscles,
in the pelvic/hip region muscles, and in the upper leg muscles,
can all be felt as deep, somewhat non-specific, poorly localized
internal pelvic pain.
Moreover, internal pelvic organ pain, such as that caused
by interstitial cystitis, vulvodynia, or irritable bowel,
can cause myofascial trigger points to occur in the muscular
wall of the pelvis and related regions. Elimination of abdominal
trigger points can eliminate the pain in types of chronic
pelvic pain. Myofascial trigger points are very common, if
not universal, in persons with chronic pelvic pain that is
severe. The levator ani muscles, the obturator internus, the
piriformis muscle, the adductor magnus muscle, and the lower
abdominal muscles are commonly involved in pelvic floor pain
associated with visceral organ dysfunction. The pain of pelvic
floor myofascial pain syndrome can be every bit as severe
as CRPS, and may suggest CRPS as a diagnosis. However, treatment
is simpler, as it involves inactivation of muscle trigger
points to avoid their return.
Treatment Issues
The treatment of CRPS involving an extremity combines sympathetic
blocks, if needed to control pain, and physical therapy. Pain
control with medication and behavioral modification techniques
like biofeedback is essential. Desensitization of the hypersensitive
limb is also important. It is also essential to keep the affected
limb functional and moving. Treatment in the early stages
before the onset of atrophy is important. Treatment in later
stages, after atrophy has set in, is more difficult. Myofascial
trigger points, when found, should be inactivated either manually,
with dry needling or by injection with 0.25% lidocaine, or
with botulinum toxin. Trigger points aggravate the symptoms
of CRPS, and CRPS is likewise a factor that perpetuates trigger
points, aggravating muscle pain. Not all of these principles
of treatment can be applied to pelvic pain.
In the first place, not all of the clinical diagnostic features
of CRPS can be ascertained in chronic pelvic pain. The role
of myofascial trigger points in pelvic pain is important,
however. Myofascial trigger points create chronic pain that
makes local CRPS worse and local visceral pain worse. Until
myofascial trigger points are reduced or eliminated, it may
difficult to clear or reduce the symptoms of CRPS. Examination
of pelvic floor muscles, especially the levator ani in both
posterior pelvic pain problems like coccydynia and anterior
pelvic pain problems like interstitial cystitis and non-bacterial
prostatitis, can lead to effective treatment strategies that
include inactivation of levator ani and other pelvic floor
muscle trigger points. Inactivation of trigger points in these
muscles can lead to reduced visceral pain.
Summary
The diagnosis of CRPS in chronic pelvic pain is not made with
great certainty and is a questionable diagnosis. Extremely
painful chronic pelvic conditions do occur, and are frequently
consistent with states of central nervous system sensitization
that produce sensory hypersensitivity or allodynia. The treatment
concerns for both CRPS and pelvic pain are the same in many
respects: reduce pain and increase function. Restoration of
function is a goal of treatment in both of these conditions,
using trigger point inactivation and related physical therapy
modalities for this purpose. Thus, even if the diagnosis of
CRPS cannot be made with certainty in pelvic region pain,
symptomatic treatment, including the elimination of painful
myofascial trigger points, can be effective in restoring function.
In the final analysis, a comprehensive evaluation for diagnosis
and treatment by physicians and physical therapists skilled
in pelvic pain management can have very fruitful outcomes.
References
1. van der Laan L, Goris RJA. The role of an exaggerated regional
inflammatory response in the pathophysiology of CRPS. Complex
Regional Pain Syndrome, Progress in Pain Research and Management.
2001;22:183-191.
2. Luzzi G. Chronic pelvic pain syndrome. BMJ. 1999;318(7193):1227-1228.
RSDSA Review. Winter 2006
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