Background
- CRPS is a localized pain disorder that develops within 4-6 weeks following trauma to or surgery performed on an extremity.
- Its incidence is 5.5-26.2 per 100,000 per year.
- Females are affected twice as frequently; increased risk also comes from having an upper extremity injury or suffering high-energy trauma.
- As the traumatized area heals, neuropathic pain develops with associated signs and symptoms of sympathetic nervous system (SNS) dysfunction (edema, erythema or bluish discoloration, temperature asymmetry when compared with the contralateral limb).
- Coupling between adrenergic and nociceptive neurons occurs, leading to increased pain after sympathetic stimulation.
- The characteristic symptom initially is strong, burning pain, usually out of proportion to the inciting event. This begins at the site of the initial trauma, then spreads regionally with no dermatomal distribution. Hyperalgesia/allodynia are often prominent.
- There are two subgroups based on the absence of distinct nerve lesions (CRPS Type 1, which accounts for the majority of cases (88% vs. 12%)) or presence of distinct nerve lesions (CRPS Type 2).
- Budapest Clinical Diagnostic Criteria for CRPS has a sensitivity of 0.99 and specificity of 0.79 (see reference by Harden for full criteria).
Clinical Challenges
- CRPS can lead to long-term, severe, persistent pain, as well as loss of function of the painful extremity.
- There is no definitive confirmatory test, which makes diagnosis difficult.
- Awareness about differential diagnosis is advised in spontaneously developing CRPS (no trauma in about 5% of cases), when the involvement is a proximal part of the limb, such as the shoulder, or when there is primary involvement of more than one limb.
- Treatment is still driven by provider experience, as evidence-based recommendations are lacking.
Special Considerations
- Patients with PTSD have a significantly increased incidence of CRPS when compared to controls.
- Patients with higher levels of anxiety, perception of disability, and pain-related fear have been shown to have a worsened disease course. This is likely due to an increase in anxiety-associated catecholamine release.
Clinical Recommendations
- Early treatment may prevent the transition to chronic CRPS.
- First-line management should focus on maintenance and restoration of function through aggressive PT/OT (e.g. mobilization exercises, desensitization, and isometric strengthening).
- A short course of corticosteroids could be beneficial for patients in early CRPS with a prominent inflammatory component
- Patients often fear the transient increase in pain with use of the extremity; reassurance and pain reduction can facilitate functional restoration.
- Pain is reduced with bisphosphonates administered both in early (first 6 to 9 months) and established CRPS.
- Sympathetic nerve blocks can dramatically reduce pain and facilitate PT, but they are rarely useful for long-term management. A successful block is typically monitored with an increase in temperature of the affected extremity.
- Spinal cord stimulation is a more effective long-term management modality. A systematic review of 19 studies showed high-level evidence of improvements in perceived pain relief, pain score, and quality of life, as well as satisfaction with SCS.
- Multidisciplinary management including PT and psychology appears to be the most effective means to help these patients.
References:
Bussa M, Mascaro A, Cuffaro L, Rinaldi S. Adult complex regional pain syndrome type I: A narrative review. PM R. 2017;9(7):707-719.
Goebel A, Barker C, Birklein F, et al. Standards for the diagnosis and management of complex regional pain syndrome: Results of a European Pain Federation task force. Eur J Pain. 2019;23(4):641-651.
Harden NR, Bruehl S, Perez RSGM, et al. Validation of proposed diagnostic criteria (the “Budapest Criteria”) for Complex Regional Pain Syndrome. Pain. 2010;150(2):268-274.
Pardo M, Miller RD. Basics of Anesthesia. 7th ed. Elsevier - Health Sciences Division; 2017.
Shim H, Rose J, Halle S, Shekane P. Complex regional pain syndrome: a narrative review for the practising clinician. Br J Anaesth. 2019;123(2):e424-e433.