Complex Regional Pain Syndrome

synonyms:CRPS, Reflex Sympathetic Dystrophy (RSD), causalgia, minor causalgia, major causalgia, mimocausalgia, pseudocausalgia, algodystrophy, algoneurodystrophy, posttraumatic dystrophy, Sudeckís atrophy, and sympathetically maintained pain syndrome.

CRPS ICD-9

CRPS Etiology / Epidemiology / Natural History

• an exaggerated response to injury of an extremity manifested by: 1) intense or unduly prolonged pain, 2) vasomotor disturbances, 3) delayed functional recovery, and 4) various associated trophic changes. 
• Pathophysiology: unknown. sympathetic nerve disorder vs hypersensitivity to catecholamines vs local inflammation vs neural injury.
• Upper Extremity:
• Lower Extremity: symptoms in the lower extremity are more refractory to intervention than those in the upper extremity.
• Knee: the most common inciting incident is injury or operation to the patella(64%).  Patellar osteoporosis is the most common x-ray change and is typically seen within 2-4 weeks. 

CRPS Anatomy

CRPS Clinical Evaluation

• Pain or allydynia/hyperalgesia not limited to the territory of a single peripheral nerve and disproportionate to inciting event.
• Edmea, changes in skin blood flow.
• Skin temperature changes.

CRPS Xray / Diagnositc Tests

• Xray indicated to rule out other causes. Generally normal initially. Advanced stages may show subchondral osteopenia / bone demineralization.
• Bone scans: Generally show increased periarticular uptake in each phase, decreased flow has been reported in the acute setting. Specificity of 75% to 98% and a sensitivity of only 50% . (Teasdall RD, Foot Ankle Clin 1998;3:485).
• MRI: no proven diagnostic value.
• Phentolamine (total dose 25-35 mg), an alpha1-adrenergic sympathetic blocking agent with a very short duration of action has been proposed as a diagnostic test for CRPS. (Raja SN, Anesthesiology 1991;74:691)
• EMG/NCV: Generally normal. Consider to evaluate for associated nerve lesion. EMG is painful, especially in CRPS patients and may worsen their condition.

CRPS Classification / Treatment

• Acute: <3 months. Warm, red, edematous extremity; aching, burning pain; intolerance have to cold; altered sweat pattern; joint stiffness without any significant effusion; hyperesthetic skin; no fixed joint contractures. Xray: normal, +/- abnormal uptake on bone scan.
• Dystrophic: 3-6 months. Cool, cyanotic, edematous extremity; shiny, hyperesthetic skin; fixed contractures; fibrotic changes occur in the synovium. Xray: subchondral osteopenia; +/- abnormal uptake on bone scan.
• Atrophic: >6months. Loss of hair, nails, skin folds; fixed contractures; muscle wasting. Xray: bone demineralization.
• Type I= formerly termed "reflex sympathetic dystrophy", occurs with no definable nerve lesion. TypeII=formerly termed "causalgia", cases with a defialbe nerve lesion.
• No proven treatment algorithm.
• Best managed with multidisciplinary team: orthopaedic surgeon, anesthesiologist, physiatrist, physical therapist, occupational therapist, and psychiatrist.
• Physical therapy: control edema, prevent joint contracture; beneficial in all stages of CRPS.
• Bretylium intravenous regional sympathetic block: affected extremity is exsanguinated and placed under 300-mm Hg tourniquet control for 20 min. 0.5% lidocaine and bretylium 1.5 mg/kg is infused into a vein. (Hord AH, Anesth Analg 1992;74:818)
• Sympathetic local anesthetic blockade. Generally lidocaine or bupivacaine introduced via a needle into the paravertebral sympathetic ganglia. (O'Brien SJ, AJSM 1995 23: 655)
• Continuous epidural anesthesia. Epidural block anesthesia instituted with an indwelling catheter with continuous passive motion, manipulation (as necessary), stimulation of muscles, and alternating hot and cold soaks over @ 4 days. (Cooper DE, JBJS 1989;71A;365)
• Alpha-adrenergic blocking agents: Phenoxybenzamine and prazosin (Muizelaar JP, Clin Neurol Neurosurg 1997;99:26)
• Calcium channel blockers: Nifedipine (Muizelaar JP, Clin Neurol Neurosurg 1997;99:26)
• Bisphosphonates: consider for long-standing CRPS with osteopenia. (Adami S, Ann Rheum Dis. 1997;56:201)
• Also consider: anticonvulsant (gabapentin), oral beta blocker (propranolol), antiarrhythmic (mexiletine).
• Narcotic: little restorative value. Can result in drug dependence without improving function.
• Beware of social issues (liability, workers compensation, disability) that may provide a financial disincentive for patients to report improvement.

CRPS Associated Injuries / Differential Diagnosis

• Soft-tissue Infection
• Osteitis
• Nonunion
• Rheumatoid arthritis
• Polyneuropathy / neuritis
• Tumor

CRPS Complications

CRPS Follow-up Care

CRPS Review References

• Cooper DE, DeLee JC: Reflex sympathetic dystrophy of the knee.  J Am Acad Orthop Surg 1994;2:79-86.
• Hogan CJ, JAAOS 2002;10:281

°