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Complex Regional Pain Syndrome

Changes in skin color, texture and temperature, accompanied by intense pain, usually in the arms and legs can be a sign of Complex Regional Pain Syndrome (CRPS). CRPS can make a normal everyday stimulus, like the touch of a loved one or a soft breeze across the skin painful, and a normally painful stimulus excruciating. Swelling, changes in hair growth, difficulty moving, have all been reported in conjunction with CRPS.

CRPS also goes by the name Reflex Sympathetic Dystrophy (RSD) – an older name for the SAME condition.

What causes CRPS is not fully understood, although several different mechanisms seem to be at play. The consensus among clinicians is that an injury, minor or traumatic, leads to a dysfunction in the central and/or peripheral nervous systems. At this time, CRPS is a perplexing condition and there is no one test that can render a diagnosis unequivocally.

Complex Regional Pain Syndrome is a difficult diagnosis of exclusion and many criteria must be satisfied across several categories for it to be determined in the clinical sense. Fortunately, the physicians at the Ainsworth Institute of Pain Management are experts in navigating the intricacies of CRPS and can offer you unique and effective treatment options.

What is Complex Regional Pain Syndrome?

CRPS was originally known as Reflex Sympathetic Dystrophy or RSD. RSD was seen as a significant problem for years and was renamed Complex Regional Pain Syndrome in 1994 by the International Association for the Study of Pain (IASP). The condition is exactly the same but is was thought the new designation more effectively represented the characteristics of its debilitating nature.

A succinct, technical definition of CRPS:
CRPS describes an array of painful conditions that are characterized by a continuing (spontaneous and/or evoked) pain that is seemingly disproportionate in time or degree to the usual course of any known trauma or other lesion. The pain is regional (not in a specific nerve territory or dermatome) and usually has a distal predominance of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings. The syndrome shows variable progression over time.[2]

Although CRPS can occur at any age, the average age of diagnosis is 42. It is three times more likely to effect women and is most commonly felt in the upper and lower extremities. Incidences of CRPS among children and adolescents is on the rise.  Other syndromes such as Chronic Pelvic Pain [1] share many of the characteristics of CRPS and have significant similarities.

Learn More About Our FDA-Approved Clinical Trial on CRPS

The Two Types of CRPS

There are two classifications of Complex Regional Pain Syndrome, Types I and II. The main difference is the presence of an identifiably nerve injury (Type II); otherwise the signs and symptoms of both conditions are clinically indistinguishable.

CRPS I (Reflex Sympathetic Dystrophy)
1. The presence of initiating noxious event or a cause of immobilization.
2. Continuing pain, allodynia, or hyperalgesia with which the pain is disproportionate to any inciting event.
3. Evidence at some time of edema, changes in skin blood flow, or abnormal sudomotor activity in the region of the pain.
4. This diagnosis is excluded by existence of conditions that would otherwise account for the degree of pain and dysfunction.

CRPS II (Causalgia)
1. The presence of continuing pain, allodynia, or hyperalgesia after a neve injury, not necessarily limited to the distribution of the injured nerve.
2. Evidence at some time of edema, changes in skin blood flow, or abnormal sudomotor in the region of the pain.
3. The diagnosis is excluded by the existence of conditions that would otherwise account for the degree of pain and dysfunction.

Source: Stanton-Hicks M: Complex regional pain syndrome. Anesthesiol Clin North Am 21:733–744, 2003.

What are the Symptoms?

Complex Regional Pain Syndrome CRPSPain

The symptoms of CRPS usually manifest around the area of an injury, typically minor. Intense pain is the hallmark symptom. As mentioned above, moving or touching the afflicted area (usually a limb) can be excruciating and intolerable. The pain associated with CRPS can be further classified:

Allodynia the perception of pain to a stimulus that does not normally cause pain (i.e. gust of wind across the skin)

Hyperalgesia a condition whereby a normally painful stimulus is abnormally painful; an abnormal increase in sensitivity to a sensory stimulus

In addition to pain, other symptoms typically related to CRPS are:

 Inflammation, swelling
 Joint stiffness
 Skin hypersensitivity
 Skin color changes; pale, red, purple, blotchy
 Skin texture changes; sweaty, thin, shiny
 Skin temperature changes; warm, hot, cool, cold
 Difficulty moving the body area (e.g., hand, arm, leg, foot)
 Hair growth changes
 Growth changes of finger and toe nails
 Muscle atrophy
 Decreased range of motion of joints in the area of the pain

The Stages of CRPS

There a generally considered to be 3 phases or stages for CRPS. It is important to remember these stages are more based on the presence, absence or evolution of the signs and symptoms, rather than the length of time.

Acute Stage (Stage 1): 1-3 months after onsetStages of Complex Regional Pain Syndrome CRPS

Burning pain
Increased sensitive to touch
Increased pain
Accelerated hair/nail growth
Tenderness or stiffness in the joint

Dystrophic Stage (Stage 2): 3-6 months after onset
Pain is constant, throbbing, burning, aching, crushing and exacerbated by any stimuli (allodynia)

Limb is still swollen/edematous
Cold and discolored with a mottled appearance
Brittle and rigid nails

Atrophic Stage (Stage 3): no time line, can be indefinite
Pain may now spread

Tissue damage may be irreversible
Skin is cool, thin and shiny
Joint contracture and muscle atrophy

What are the Causes?

shutterstock_84331045It is not known exactly what causes CRPS. Although nerve damage as a result of injury appears to play a big part, it is not known what kind of injuries or mechanisms of trauma will lead to the condition. In other words, two people can suffer the exact same injury and only one ends up with CRPS. What’s more, the injury can be as innocuous as a kick in the shin while playing soccer or as extreme as a crush injury from a motor vehicle accident.

The general consensus amongst scientists and treating physicians is there is no one cause or factor involved in the development of CRPS, rather multiple mechanisms involved. Below is a list of possibilities:

Altered Cutaneous Innervation Following Injury: Since some degree of nerve injury is needed to initiate the cascade of events leading up to CRPS [3],[4], much attention has been paid to the characteristics of nerves in the affected limbs. In a study by Albrecht et al, a reduction in C- and A-delta fiber density (nerve fibers involved in transmitting pain) in CRPS-affected limbs as compared to the non-affected sites on the same limb.[5]

Peripheral Sensitization: After an injury, the nerve fibers involved in sending sensations away from the injury toward the Central Nervous System (CNS) are traumatized and release neuropeptides (i.e. Bradykinin and Substance P). This in turn causes an increase in firing pain fibers and receptors to noxious stimuli and reduced firing threshold to mechanical and thermal stimuli.[2] This is theorized to account for the hyperalgiesia and allodynia that has become synonymous with CRPS.[6]

Central Sensitization: The process for central sensitization is similar to peripheral sensitization. Persistent pain input associated with a nerve injury from localized tissue trauma leads to increased activity from nociceptive neurons in the spinal cord.[7] The central sensitization is mediated by the release of neuropeptides and glutamate acting at N-methyl-D-aspartic (NMDA) receptors of the spinal cord.[8] This activity leads to an enhanced/increased response to non-noxious stimuli (allodynia) and noxious stimuli (hyperalgesia).

Sympathetically Mediated Pain: Much attention has been paid to the contribution of the Sympathetic Nervous System (SNS) to the initiation and maintenance of CRPS. In patients with CRPS whose pain had been previously relieved by a Sympathetic Block, an intradermal injection of epinephrine results in an immediate return of spontaneous pain and allodynia.[9]

Inflammatory Mediators: Evidence has suggested there may be an exaggerated inflammatory process involved in CRPS, more specifically, the acute phase. This may occur through the release of pro-inflammatory cytokines and neuropeptides from white blood cells. These mediators can increase tissue permeability causing vasodilation, leading to the warmth and swelling noted in the early stages of CRPS.

Cortical Reorganization: With the advent of more complex imaging (i.e. functional MRI or fMRI and single photon emission CT or SPECT), changes in the CNS in those suffering from CRPS can now be studied. Of note, the areas of the brain corresponding to the affected limb or body part with CRPS show an increase in representation in the brain. In a study by Maihofner et al, there was an observed increase in representation in the brain for the hand affected with CRPS as compared to the unaffected.[10]

How is a Diagnosis of CRPS Determined?

There is no diagnostic test considered to be the “gold standard” for diagnosing CRPS, but there are several tests that may have some clinical utility although a negative result may not necessarily rule out the condition. Temperature measurement (either through infrared thermometry or surface measurement) has been of some use and most notably, Triple-Phase Bone Scan/Scintigraphy has been suggested by many to be great value in diagnosing CRPS.

Diagnosing CRPS, therefore, becomes a complicated and multifaceted process. Many criteria must be met and other conditions excluded before a determination is made in the clinical sense. For a clinical diagnosis of CRPS, the patient must satisfy the following four benchmarks:

1. Continuing pain, which is disproportionate to any inciting event

2. Must report at least one symptom in 3 out of the 4 following categories:

SENSORY: Reports hyperesthesia (abnormal increase in sensitivity to a stimulus) and/or allodynia (pain from a stimulus that would not normally provoke pain)
VASOMOTOR: Reports of temperature asymmetry and/or sweating changes and/or cold asymmetry
SUDOMOTOR/EDMA: Evidence of edema and/or sweating changes and/or sweating asymmetry
MOTOR/TROPHIC: Reports of decreased range of motion and/or motor dysfunction [weakness, tremor, dystonia (sustained muscle contractions)] and/or trophic changes (hair, nail, skin)

3. Must display at least one sign at time of evaluation in 2 or more of the following categories:

SENSORY: Evidence of hyperalgesia (to pinprick) and/or allodynia (to light touch and/or temperature sensation and/or deep somatic pressure and/or joint movement)
VASOMOTOR: Evidence of temperature asymmetry (
SUDOMOTOR/EDMA: Evidence of edema and/or sweating changes and/or sweating asymmetry
MOTOR/TROPHIC: Evidence of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)

4. There is no other diagnosis that better explains the signs and symptoms

What are my Treatment Options?

Diagnosing Complex Regional Pain Syndrome CRPSIf you believe you are suffering from CRPS, it is imperative you contact a pain management doctor with experience diagnosing and treating the condition. Since a diagnosis of CRPS is based on clinical presentation and the patient’s signs and symptoms, the physician will need to first obtain a complete history and conduct a comprehensive physical exam.

At the Ainsworth Institute of Pain Management, our physicians can offer treatments for CRPS that are not available anywhere else in New York City. Our treatment philosophy for CRPS is centered on a multimodal pharmacologic therapy and multidisciplinary team approach, with effective pain control, functional restoration, and enhancement of psychological well-being as the key elements.[2]

Interventional Pain Management Treatments

Sympathetic Nerve Blocks – These injections have been utilized as both a diagnostic and therapeutic tool. Your physician will insert a thin needle under radiographic guidance, through the skin, targeting the SNS. The nerves of the SNS are then “blocked” with small amount of local anesthetic. The pain relief from these injections can be dramatic. Procedures that focus on facial pain and upper extremity CRPS include the Stellate Ganglion Block. Lumbar Sympathetic Blocks are typically performed for lower extremity CRPS.

IV Infusion Therapy – A simple procedure commonly performed in the office. Your doctor will place a small IV catheter and then infuse special medications intravenously in an attempt to halt the pain process.

Spinal Cord Stimulation – A procedure that utilizes technology similar to that of cardiac pacemakers. This method involves placing small electrodes into the epidural space near the spinal cord. These electrodes produce a small electrical current over the spinal cord that your brain will interpret as a gentle massage or a feeling of “champagne bubbles.” This will inhibit pain transmission and provide relief to the CRPS-affected limbs. Studies have even shown that color and appearance can be restored to the affected area.

DRG Stimulation – DRG Stimulation (aka Dorsal Root Ganglion Stimulation) is THE most powerful and effective treatment for CRPS  available in the United States.  The clinical trial (ACCURATE Study) recorded unprecedented improvements in pain and overall successes that have never before been seen for CRPS.  The procedure is almost identical to traditional Spinal Cord Stimulation, except a special system called Axium™ (available exclusively through St. Jude Medical™) provides isolated stimulation to only the DRG.  Even if you have failed traditional Spinal Cord Stimulation in the past, statistics suggest DRG Stimulation will still work! [12] 

Peripheral Nerve Stimulation – This is very similar to spinal cord stimulation, except the electrodes are placed adjacent to the affected nerves in the extremity.

Intrathecal Pumps – This is a method whereby a small catheter is placed in the subarachnoid space and minuscule amounts of medication are delivered directly to the spinal cord and the rest of the CNS. This enables your physician to provide the same medications but at a fraction dose due to the proximity to the spinal cord.

Other Treatment Options

Medication management & Pharmacologic Therapy – There are a wide-variety of medications found to be effective in treating CRPS – these include non-steroidal anti-inflammatories, membrane stabilizers, antidepressants, anticonvulsants and opioids.

Physical Therapy – Functional restoration is the hallmark of success in CRPS. Working with Physical and Occupational Therapists, treatments targeting desensitization, muscle strength, flexibility, range of motion and gait training will be employed to allow you to regain function.

Psychotherapy and Biofeedback – This is considered part of a multidisciplinary approach to treating CRPS whereby patients are trained to have a better awareness of their body. This will allow you to relax and obtain better pain relief.

The Ainsworth Institute is Here to Help

Our doctors at the Ainsworth Institute of Pain Management can help you manage the painful effects of CRPS. Dramatic improvements and even remission of CRPS are possible with the right treatment. The sooner treatment is started, the better the chances of success. Call and schedule an appointment now with one of our board-certified pain management experts.


[1] Hunter C, Davé N, Diwan S, Deer T. Neuromodulation of Pelvic Visceral Pain: A Review of the Literature and Case Series of Potential Novel Targets for Treatment. Pain Practice 2013;13(1):3-17.

[2] Benzon, Honorio. Essentials of Pain Medicine. Philadelphia: Saunders Elsevier, 2011. Print

[3] Birklein F, Schmelz M: Neuropeptides, neurogenic inflammation and complex regional pain syndrome (CRPS). Neurosci Lett. 2008; 437:199-202.

[4] Oaklander AL, Rissmiller JG, Gelman LB, et al.: Evidence of focal small-fiber axonal degeneration in complex regional pain syndrome-I (reflex sympathetic dystrophy). Pain. 2006; 120:235-243.

[5] Albrecht PJ, Hines S, Eisenberg E, Pud D, Finlay DR, Connolly MK, Par M, Davar G, Rice FL: Pathologic alterations of cutaneous innervation and vasculature in affected limbs from patients with complex regional pain syndrome. Pain. 2006; 120:244-266.

[6] Couture R, Harrisson M, Vianna RM, Cloutier F: Kinin receptors in pain and inflammation. Eur J Pharmacol. 2001; 429:161-176.

[7] Ji RR, Woolf CJ: Neuronal plasticity and signal transduction in nociceptive neurons. implications for the initiation and maintenance of pathological pain Neurobiol Dis. 2001; 8:1-10.

[8] Wang H, Kohno T, Amaya F, et al.: Bradykinin produces pain hypersensitivity by potentiating spinal cord glutamatergic synaptic transmission. J Neurosci. 2005; 25:7986-7992.

[9] Torebork E, Wahren L, Wallin G, et al.: Noradrenaline-evoked pain in neuralgia. Pain. 1995; 63:11-20.

[10] Maihofner CM, Handwerker HOM, Neundorfer BM, et al.: Patterns of cortical reorganization in complex regional pain syndrome. Neurology. 2003; 61:1707-1715.

[11] Stanton-Hicks M: Complex regional pain syndrome. Anesthesiol Clin North Am. 2003; 21:733-744.

[12] Liem L, Russo M, Huygen FJPM, Van Buyten J, et al. One-year outcomes of spinal cord stimulation of the dorsal root ganglion in the treatment of chronic neuropathic pain. Neuromodulation 2015;18:41–49.

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