Pain Management: Complex Regional Pain Syndrome

Abstract

Complex regional pain syndrome (CRPS) is a regional neuropathic pain syndrome that usually develops within a few weeks after limb trauma or surgery. CRPS presents with symptoms and exam findings that can be categorized as follows: sensory, vasomotor, sudomotor, and motor/trophic changes. CRPS is diagnosed clinically using the Budapest criteria. No specific test or imaging study can rule in or rule out CRPS; however, MRI and triple-phase bone scan may show findings suggestive of CRPS. Two subtypes of CRPS are currently accepted: CRPS type I occurs without peripheral nerve injury; CRPS type II occurs with peripheral nerve injury. Effective treatment is often difficult, and therefore requires a multidisciplinary approach, individualized to the patient. The goal of all therapies is to improve function and relieve pain. Evidence suggests vitamin C supplementation after distal limb fracture or surgery may reduce the risk of developing CRPS. Conservative therapy should be started first, and may include various oral medications (e.g., NSAIDs, gabapentin, clonidine), corticosteroid injections, and physical therapy, and psychotherapy. More advanced therapies are relatively new, have little supporting evidence, and should be pursued with appropriate specialty consultation. These include regional sympathetic blockade, ketamine infusion, neuromodulation, and surgical sympathectomy. Prognosis is variable, but most cases resolve within a few months to a year with appropriate treatment. Delayed diagnosis and inadequate therapy are associated with prolonged recovery. Approximately 10-20% of cases become chronic and refractory to any therapy.

Keywords

complex regional pain syndrome, neuropathic pain, Budapest criteria, vasomotor, sudomotor, regional sympathetic dystrophy, causalgia

ICD-10-CM Codes

G90. 511	CRPS type I upper limb, right
G90.512	CRPS type I upper limb, left
G90.521	CRPS type I lower limb, right
G90.5322	CRPS type I lower limb, left
G56.41	Causalgia (CRPS type II) upper limb, right
G56.42	Causalgia (CRPS type II) upper limb, left
G57.71	Causalgia (CRPS type II) lower limb, right
G57.72	Causalgia (CRPS type II) lower limb, left

Key Concepts

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Complex regional pain syndrome (CRPS) is a regional neuropathic pain that does not follow the usual distribution of a dermatome or nerve territory.
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Associated with abnormal sensory, autonomic, motor, and/or trophic changes
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Most commonly develops after distal limb trauma or surgery
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CRPS diagnosed clinically using the Budapest criteria, which was approved by International Association for the Study of Pain (IASP) in 2012

History

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Usually occurs 4 to 6 weeks after inciting event
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Risk factors: female, postmenopausal, recent distal radius fracture, ankle dislocation and/or intra-articular fracture, immobilization, high levels of reported pain after trauma
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Pain is commonly felt deep within the limb and is described as burning, searing, or shooting; worsens with movement, contact, temperature variation, and stress.

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Four symptom categories: sensory, vasomotor, sudomotor/edema, motor/trophic ( Table 23.1 )

TABLE 23.1

Budapest Clinical Diagnostic Criteria for Complex Regional Pain Syndrome

	Criteria	Clinical Categories of Signs and Symptoms
1	Continuing pain, which is disproportionate to any inciting event	Sensory—hyperalgesia, hypoesthesia, allodynia Vasomotor—skin color or temperature changes/asymmetry Sudomotor/edema—edema and/or sweating changes and/or sweating asymmetry Motor/trophic—decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)
2	Must report at least one symptom in three of the four clinical categories
3	Must display at least one sign at the time of assessment in two or more of the four clinical categories
4	There is no other diagnosis that better explains the signs and symptoms

Physical Examination

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Inspect area carefully and compare findings with contralateral limb (see Table 23.1 ).
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Observe gait and posture for any compensatory movements and guarding.
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Inspect extremity for edema, changes in hair/nail growth, and skin color/appearance.
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Assessment of skin temperature, tone, and texture.
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Evaluate range of motion, strength, and reflexes.
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Neurologic: pinprick, light touch, temperature, deep somatic pressure.