Complex regional pain syndrome

Background

Abbreviation

• CRPS

Other Names

• Reflex sympathetic dystrophy (RSD)
• Causalgia
• Reflex neurovascular dystrophy (RND)
• Amplified musculoskeletal pain syndrome (AMPS)

Definition

• Disorder of the extremities characterized by regional pain that is disproportionate in time or degree to the usual course of any known trauma or other lesion
• Pain is not in a specific nerve territory or dermatome
• Pain usually has a distal predominance of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings
• CRPS often worsens over time
• 35% of pts report symptoms throughout their whole body.

Sub-Types

• Type I
  • NO evidence of peripheral nerve injury (edema, erythema, numbness), 90% of clinical presentations
• Type II
  • YES evidence of peripheral nerve injury, considered more serve type

Causes

• Generally unknown
• Inciting event
  • Found in about 90% of cases - usually begin 4-6wks after fxs, crush injuries, sprains, and surgery.
• Proposed mechanisms
  • Classic inflammation, neurogenic inflammation, and maladaptive changes in pain perception at the level of the central nervous system

Clinical Features

• Pain — burning, stinging, or tearing sensation that is felt deep inside the limb, usually continuous but can be paroxysmal.
• Sensory — hyperalgesia, allodynia, or hypesthesia
• Motor — weakness, occasional tremor, myoclonus, or dystonic postures
• Skin — warmth, skin color changes, sweating, or edema, other skin/hair/nail changes

Physical exams findings possible in Type II CRPS

Differential Diagnosis

• Cellulitis
• DVT
• Infection
• Compartment syndrome
• Peripheral Vascular Disease
• Peripheral neuropathy
• Thoracic outlet syndrome
• Rheumatoid arthritis
• Chronic inflammatory autoimmune disease
• Raynaud phenomenon
• Erythromelalgia
• Conversion disorder
• Factitious disorder

Evaluation

Clinical: Budapest consensus criteria:

• At least 1 symptom in three of the following four categories:

1. Sensory - allodynia, hyperalgesia
2. Vasomotor: temperature asymmetry, skin color changes, skin color asymmetry
3. Sudomotor/edema: edema, sweating
4. Motor/trophic: decreased ROM, weakness, tremor, dystonia, trophic changes (hair, nail, skin)

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

R/o Emergent Etiologies

• XR
• CBC
• Ultrasound

Other Imaging

• CT/MRI/XR are all NOT diagnostic for CRPS

Management

Ketamine for Flare-Ups

• Ketamine initial bolus - 0.2–0.3 mg/kg of infused over 10mins.
  • Avoid IV push - could cause dissociative side effects.
  • Diagnostic- pain should resolve by the end of the 10min bolus and if so, continue ketamine.
• Ketamine infusion - 0.2 mg/kg/hr over 4-6hrs.

No discharge prescription usually required. If needed:

• Ibuprofen - 400-800 mg TID or naproxen 250-500 mg BID
• Amitriptyline or nortriptyline - 10-25 mg at bedtime as initial dose for both
• Gabapentin - 100 mg-300 mg at bed time
• Topical lidocaine cream - 2-5% or topical capsaicin cream 0.075%

Opioids should NOT be used for chronic or acute CRPS. Pt education on this is important.

Disposition

• Outpatient f/u with pain management
• Referral for PT/OT - important for all CRPS pts
• Consider psychiatric referral if warranted

See Also

Acute pain management

External Links

ACEP - Tips for Managing CRPS

NIH - Validation of Budapest Criteria for CRPS