Pain Management
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Complex regional pain syndrome (CRPS)
Complex regional pain syndrome (CRPS) is a chronic progressive disease characterized by severe pain, swelling and changes in the skin.  The International Association for the Study of Pain has divided CRPS into two types based on the presence of nerve lesion following the injury.
Type I, formerly known as reflex sympathetic dystrophy (RSD), Sudeck's atrophy, reflex neurovascular dystrophy (RND) or algoneurodystrophy, does not have demonstrable nerve lesions.
Type II, formerly known as causalgia, has evidence of obvious nerve damage.
The cause of this syndrome is currently unknown. Precipitating factors include injury and surgery, although there are documented cases that have no demonstrable injury to the original site.
CRPS of Right Arm
The pathophysiology of CRPS is not fully understood. “Physiological wind-up” and central nervous system (CNS) sensitization, are key neurologic processes that appear to be involved in the induction and maintenance of CRPS. There is compelling evidence that the N-methyl-D-aspartate (NMDA) receptor has significant involvement in the CNS sensitization process. It is also hypothesized that elevated CNS glutamate levels promote "physiological wind-up" and CNS sensitization.In addition, there is experimental evidence that demonstrates NMDA receptors in peripheral nerves.Because immunological functions can modulate CNS physiology, it has also been hypothesized that a variety of immune processes may contribute to the initial development and maintenance of peripheral and central sensitization.Furthermore, trauma related cytokine release, exaggerated neurogenic inflammation, sympathetic afferent coupling, adrenoreceptor pathology, glial cell activation, cortical reorganisation, and damage (e.g. by free radicals) are all concepts that have been implicated in the pathophysiology of CRPS.
The symptoms of CRPS usually manifest near the site of an injury, either major or minor. The most common symptoms overall are burning and electrical sensations, described to be like "shooting pain." The patient may also experience muscle spasms, local swelling, abnormally increased sweating, changes in skin temperature and color, softening and thinning of bones, joint tenderness or stiffness, restricted or painful movement.
The pain of CRPS is continuous and may be heightened by emotional or physical stress. Moving or touching the limb is often intolerable. The symptoms of CRPS vary in severity and duration. There are three variants of CRPS, previously thought of as stages. It is now believed that patients with CRPS do not progress through these stages sequentially. These stages may not be time-constrained, and could possibly event-related, such as ground-level falls or re-injuries in previous areas. Instead, patients are likely to have one of the three following types of disease progression:
Type one is characterized by severe, burning pain at the site of the injury. Muscle spasm, joint stiffness, restricted mobility, rapid hair and nail growth, and vasospasm (a constriction of the blood vessels) that affects color and temperature of the skin can also occur.
Type two is characterized by more intense pain. Swelling spreads, hair growth diminishes, nails become cracked, brittle, grooved, and spotty, osteoporosis becomes severe and diffuse, joints thicken, and muscles atrophy.
Type three is characterized by irreversible changes in the skin and bones, while the pain becomes unyielding and may involve the entire limb. There is marked muscle atrophy, severely limited mobility of the affected area, and flexor tendon contractions (contractions of the muscles and tendons that flex the joints). Occasionally the limb is displaced from its normal position, and marked bone softening and thinning is more dispersed.
CRPS types I and II share the common diagnostic criteria shown below. Spontaneous pain or allodynia is not limited to the territory of a single peripheral nerve, and is disproportionate to the inciting event.
There is a history of edema, skin blood flow abnormality, or abnormal sweating in the region of the pain since the inciting event.
No other conditions can account for the degree of pain and dysfunction.
The two types differ only in the nature of the inciting event. Type I CRPS develops following an initiating noxious event that may or may not have been traumatic, while type II CRPS develops after a nerve injury.
No specific test is available for CRPS, which is diagnosed primarily through observation of the symptoms. However, thermography, sweat testing, x-rays, electrodiagnostics, and sympathetic blocks can be used to build up a picture of the . A delay in diagnosis and/or treatment for this syndrome can result in severe physical and psychological problems. Early recognition and prompt treatment provide the greatest opportunity for recovery.
The International Association for the Study of Pain (IASP) lists the diagnostic criteria for complex regional pain syndrome I (CRPS I) (RSDS) as follows:
The presence of an initiating noxious event or a cause of immobilization
Continuing pain, allodynia (perception of pain from a nonpainful stimulus), or hyperalgesia disproportionate to the inciting event
Evidence at some time of edema, changes in skin blood flow, or abnormal sudomotor activity in the area of pain
The diagnosis is excluded by the existence of any condition that would otherwise account for the degree of pain and dysfunction.
According to the IASP, CRPS II (causalgia) is diagnosed as follows:
The presence of continuing pain, allodynia, or hyperalgesia after a nerve injury, not necessarily limited to the distribution of the injured nerve
Evidence at some time of edema, changes in skin blood flow, or abnormal sudomotor activity in the region of pain
The diagnosis is excluded by the existence of any condition that would otherwise account for the degree of pain and dysfunction.
The IASP criteria for CRPS I diagnosis has shown a sensitivity ranging from 98-100% and a specificity ranging from 36%-55%. Per the IASP guidelines, interobserver reliability for CRPS I diagnosis is poor. Two other criteria used for CRPS I diagnosis are Bruehl's criteria and Veldman's criteria which have moderate to good interobserver reliability. In the absence of clear evidence supporting 1 set of criteria over the others, clinicians may use IASP, Bruehl’s, or Veldman’s clinical criteria for diagnosis. While the IASP criteria are nonspecific and possibly not as reproducible as Bruehl’s or Veldman’s criteria, they are cited more widely the literature including treatment trials.
Thermography is a diagnostic technique for measuring blood flow by determining the variations in heat emitted from the body. A color-coded "thermogram" of a person in pain often shows an altered blood supply to the painful area, appearing as a different shade (abnormally pale or violet) than the surrounding areas of the corresponding part on the other side of the body. A difference of 1.0°C between two symmetrical body parts is considered significant
Patchy osteoporosis, which may be due to disuse of the affected extremity, can be detected through X-ray imagery as early as two weeks after the onset of CRPS.
Electrodiagnostic testing
The nerve injury that characterizes type II CRPS can be detected by electromyography. In contrast to peripheral mononeuropathy, the symptoms of type 2 CRPS extend beyond the distribution of the affected peripheral nerve.
The general strategy in CRPS treatment is often multi-disciplinary, with the use of different types of medications combined with distinct physical therapies.
Physicians use a variety of drugs to treat CRPS, including antidepressants, anti-inflammatories such as corticosteroids and COX-inhibitors such as piroxicam, bisphosphonates, vasodilators, GABA analogs such gabapentin and pregabalin, and alpha- or beta-adrenergic-blocking compounds, and the entire pharmacy of opioids. Although many different drugs are used, there is not much supportive evidence for most of them. This doesn't necessarily reflect evidence that they don't work, just a lack of evidence that they do.
Physical and occupational therapy
Physical and occupational therapy are important components of the management of CRPS primarily by desensitizing the affected body part, restoring motion, and improving function. some people at certain stages of the disease are incapable of participating in physical therapy due to touch intolerance. This may be where Graded Motor Imagery and Mirror Therapy (see below) are particularly helpful. People with CRPS often develop guarding behaviors where they avoid using or touching the affected limb. This inactivity exacerbates the disease and perpetuates the pain cycle. Therefore optimizing the multimodal treatment is paramount to allow for use of the involved body part.
Mirror therapy
Recent research has utilized mirror therapy to significantly reduce pain levels in CRPS patients, where the affected limb is placed within a mirror box, such that the unaffected limb is reflected in a way as to make the patient think they are looking at the affected limb. Movement of this reflected normal limb is then performed such that it looks to the patient as though they are performing movement with the affected limb (although it will be pain free due to the fact it is a normal limb being reflected). Following this movement of the normal limb, when the affected limb is moved, levels of pain are reduced and over a longer period significant changes between controls and intervention groups have been shown. Concepts of neural plasticity within the brain have been hypothesized as to why this effect occurs, and similar mirror therapy has been used successfully to treat phantom limb pain
Graded motor imagery
Because many studies have shown problems with the central nervous system and brain in people with CRPS, recently, treatments have been developed that target these problems. One treatment, (graded motor imagery) has now been tested in three randomised controlled trials and has shown to be effective at reducing pain and disability in people with chronic CRPS, or phantom limb pain after amputation or avulsion injury of the brachial plexus. The number needed to treat for a 50% reduction in pain was about 3.
 Graded exposure to fearful activities
Preliminary evidence from a replicated case series suggests that graded exposure to fearful activities is helpful for CRPS patients with a high fear of activity.[35] A randomised controlled trial is currently underway.
Local anaesthetic blocks/injections
Injection of a local anesthetic such as lidocaine is often the first step in treatment. Injections are repeated as needed. However, early intervention with non-invasive management may be preferred to repeated nerve blockade.
Spinal cord stimulators
Neurostimulation (spinal cord stimulator) may also be surgically implanted to reduce the pain by directly stimulating the spinal cord. These devices place electrodes either in the epidural space (space above the spinal cord) or directly over nerves located outside the central nervous system. Implantable drug pumps may also be used to deliver pain medication directly to the cerebrospinal fluid which allows powerful opioids to be used in a much smaller dose than when taken orally. A recent review of CRPS treatment concluded: "Some common treatments (e.g., local anesthetic blockade of sympathetic ganglia) are not supported by the aggregate of published studies and should be used less frequently. Other treatments with encouraging published results (e.g., neural stimulators) are not used often enough.
Surgical, chemical, or radiofrequency sympathectomy — interruption of the affected portion of the sympathetic nervous system — can be used as a last resort in patients with impending tissue loss, edema, recurrent infection, or ischemic necrosis. However, there is little evidence that these permanent interventions alter the pain symptoms of the affected patients.
Ketamine, a potent anesthetic, is being used as an experimental and controversial treatment for Complex Regional Pain Syndrome.  The hypothesis is that ketamine  manipulates NMDA receptors which might reboot aberrant brain activity.
 prolonged painful stimulus causes an extraordinary release of glutamate from peripheral nociceptive afferents onto dorsal horn neurons within the spinal cord. The glutamate released, in turn, stimulates NMDA receptors on second-order neurons that produce the phenomena of windup and central sensitization. It is reasonable to consider that, by blocking NMDA receptors, one might also be able to block cellular mechanisms supporting windup and central sensitization [4–7,15]. Ketamine is the only potent NMDA-blocking drug currently available for clinical use
Similar Disorders
CRPS has characteristics similar to those of other disorders, such as shoulder-hand syndrome, which sometimes occurs after a heart attack and is marked by pain and stiffness in the arm and shoulder; Sudeck syndrome, which is prevalent in older people and women and is characterized by bone changes and muscular atrophy, but is not always associated with trauma; and Steinbrocker syndrome, which includes symptoms such as gradual stiffness, discomfort, and weakness in the shoulder and hand. Erythromelalgia also shares many components of CRPS (burning pain, redness, temperature hypersensitivity, autonomic dysfunction, vasospasm), they both involve small fiber sensory neurosympathetic components. Erythromelalgia involves a lack of sweating, whereas CRPS often involves increased sweating. Subvariations of both exist. New information lends credibility to previous positions that this is an autoimmune response disease that can be caused by injury, non injury, and can progress from the injured location throughout the entire body, to include optic nerves, ear nerves, and other facial nerves. Regarding the facial nerves, the eyes seem to be most vulnerable, with no specific pattern as to one or both. It also has the ability to affect sexual function in both the male and female anatomy, though the ability to engage in sexual activity is limited by the disease itself. There is further information that some cases may have a genetic predisposition for the disease, as with other autoimmune diseases. Myasthenia Gravis is another disease that mirrors many of the symptoms of CRPS.