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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, shoulder-hand syndrome.

CRPS ICD-9

  • 337.21 (reflex sympathetic dystrophy of the upper limb)
  • 337.22 (reflex sympathetic dystrophy of the lower limb)

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: associated with distal radius fractures.
  • 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. 
  • Women/men = 3-4/1
  • Risk Factors: women, smoking, age 30-50.
  • Outcomes are better the sooner CRPS is diagnosed and treated.

CRPS Anatomy

CRPS Clinical Evaluation

  • Pain or allodynia/hyperalgesia not limited to the territory of a single peripheral nerve and disproportionate to inciting event. Pain may be described as burning, searing, throbbing, tearing.
  • Edmea, changes in skin blood flow.
  • Skin temperature changes.
  • May progress from painful/hot/swollen to painful/cold/atrophic to stiff/atrophic.
  • Allodynia = pain caused by a normally nonpainful stimulus
  • Hyperpathia = perception of pain that is delayed and extends beyond the normal nerve distribution.

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.
  • Sympatholytic Drug Administration: patients can be given injectable or oral sympatholytic drugs (IV phentolamine) to determine if they have sympathetically maintained pain (SMP) or sympathetically independent pain (SIP).

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, passive and active ROM, contrast baths, TENS, iontophoresis; beneficial in all stages of CRPS.
  • Effective Medications: prednisone, amitryptyline, gabapentin, phenytoin, amlodipine besylate, clonidine, calcitonin.
  • 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

  • Factitious Syndromes: SHAFT(sad, hostile, anxious, factitious, tenacious), Munchausen)
  • Soft-tissue Infection
  • Osteitis
  • Nonunion
  • Rheumatoid arthritis
  • Polyneuropathy / neuritis
  • Tumor

CRPS Complications

  • Chronic pain
  • Joint contractures / stiffness
  • Muscle atrophy
  • Osteopenia

CRPS Follow-up Care

  • 80% will show significant improvement if diagnosed within one year. 50% will have long-term morbidity if diagnoses after 1 year.

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
  • Griffin LY, Essentials of Musculoskeletal Care 3rd edition, AAOS, 2005

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