The hallmark of CRPS is pain and mobility problems out of proportion to those expected from the initial injury.
“Of all the chronic neuropathic pain syndromes, none has perplexed patient, clinician, and scientist more than the complex regional pain syndromes (CRPS), heretofore known as reflex sympathetic dystrophy (RSD) and causalgia.”
- Galer BS CRPS In Loeser J (ed) Bonica’s Management of Pain 3rd Ed. Lippincott Williams & Wilkins 2001 p 388
Complex Regional Pain Syndrome is the new term for what we used to call RSD or causalgia. Symptoms can develop into CRPS from a major nerve injury (CRPS Type II) or from minimal or no trauma (CRPS Type I).
The first stage typically lasts about 3 months and starts with severe, burning localized pain, hyperesthesia, localized edema, stiffness and vasospasm (warm, red and dry at first, then changes to cyanotic, cold and sweaty).
The second stage (which lasts 3-6 months), pain becomes more severe and diffuse. Edema spreads, hair becomes scant, and nails become brittle, cracked and grooved. Osteoporosis appears and spreads while muscles waste.
The third stage Pain may spread to the entire limb in stage 3, with marked muscle atrophy, extreme joint weakness and limited mobility. Bone deossification becomes diffuse. Contractures are often seen, with near mummification of the extremities.
Pain from CRPS:
The hallmark of CRPS is pain and mobility problems out of proportion to those expected from the initial injury. The first and primary complaint occurring in one or more extremities is described as severe, constant, burning and/or deep aching pain. All tactile stimulation of the skin (e.g. wearing clothing, a light breeze) may be perceived as painful (allodynia). Repetitive tactile stimulation (e.g. tapping on the skin) may cause increasing pain with each tap and when the repetitive stimulation stops, there may be a prolonged after-sensation of pain (hyperpathia). There may be diffuse tenderness or point-tender spots in the muscles of the affected region due to small muscle spasms called muscle trigger points (myofascial pain syndrome). There may be spontaneous sharp jabs of pain in the affected region that seem to come from nowhere (paroxysmal dysesthesias and lancinating pains).
Skin changes in CRPS:
The skin may appear shiny (dystrophy-atrophy), dry or scaly. Hair may initially grow coarse and then thin. Nails in the affected extremity may be more brittle, grow faster and then slower. Faster growing nails is almost proof that the patient has CRPS.
CRPS is associated with a variety of skin disorders including rashes, ulcers and pustules. Although extremely rare, some patients have required amputation of an extremity due to life-threatening recurring infections of the skin. Abnormal sympathetic (vasomotor changes) activity may be associated with skin that is either warm or cold to touch. The patient may perceive sensations of warmth or coolness in the affected limb without even touching it (vasomotor changes). The skin may show increased sweating (sudomotor changes) or increased chilling of the skin with goose flesh (pilomotor changes). Changes in skin color can range from a white mottled appearance to a red or blue appearance. Changes in skin color (and pain) can be triggered by changes in the room temperature, especially cold environments. However, many of these changes occur without any apparent provocation.
Reflex sympathetic dystrophy (RSD) or Complex Regional Pain Syndrome (CRPS) is a malignant pain syndrome most often seen in the distal upper or lower extremities, but in variant forms also affects more proximal structures. It is characterized by:
- extremity pain, often severe (often seen in a stocking or glove pattern)
- most commonly, involvement of the hand or foot, following injury to that structure or to a proximal limb structure;
- allodynia (pain to non-painful touch) and hyperpathia;
- peripheral thermal abnormalities;
- other symptoms and signs of local autonomic nervous system dysfunction may be present, including locally increased or decreased sweating and edema;
- local trophic changes;
- progressive osteoporosis of the affected extremity
- flexion contracture with significant atrophy
CRPS usually remains restricted to one limb, but it can spread to other body parts. Processes in the spinal cord as well as supraspinal changes are responsible for spontaneous spread in CRPS to other extremities.
Diagnosis is made largely on the basis of history and clinical examination. A dynamic phase bone scan may help to document perfusion abnormality and is the most sensitive and specific study applicable in diagnosis. Local sympathetic anesthetic block, performed for treatment, typically results in pain relief outlasting the transient anesthetic effect, which is supportive of the diagnosis.
Evaporative skin testing with loss of temperature discrimination and development of allodynia upon evaporation is a useful screening tool.
Electrodiagnostic testing to exclude nerve entrapment as well as Neurodiagnostic imaging may be necessary to exclude a neuraxial pathology, such as a bulging disc.
Patients with ischemic rest pain (pain from insufficient blood supply due to advanced CRPS):
- Frequently are sleep deprived
- Are limited in mobility and activities of daily living
- Often will consent to amputation for pain relief
- Often are unable to obtain adequate pain relief from narcotic medication
- Rarely improve spontaneously, unless the blood perfusion to the affected area can be improved
- Have a high incidence of major depression disorder and are high risk of suicide
Early diagnosis in the first six months to maximal two years is the key to successful treatment. Surgical sympathectomy procedures (removal of a part of the chain of sympathetic ganglia on the side of the spine) have limited application for the treatment of RSD.
Management options include sympathetic blocks utilizing regional anesthetic techniques and radiofrequency thermoneurolysis or neuromodulation with spinal cord stimulation or peripheral nerve stimulation. Radiofrequency neurolysis is an extension of a continuous regional sympathetic block or neurolytic block providing long-term relief with added safety.
Consideration of sympathetic blocks is to facilitate management of CRPS with analgesia commensurate with a program of functional restoration and sympatholysis to provide unequivocal evidence of sympathetically maintained pain. Once it is established that sympatholysis is effective in relieving not only the burning dysesthesia but also allodynia or hyperalgesia, it is important to repeat the procedure to determine whether an increasing duration of effect can be expected in any particular patient. If this is the case, these individual blocks may be all that are necessary to enable a patient to regain function. When sympatholysis completely relieves the symptoms and facilitates exercise therapy but is limited to its duration of effect, it is appropriate to consider a prolonged block using radiofrequency neurolysis.
Radiofrequency has been described for lesioning of the cervical sympathetic chain, thoracic sympathetic chain, and lumbar sympathetic chain, in cases of CRPS I and II, as well as for neuropathic pain.