# Complex Regional Pain Syndrome

Diagnose CRPS clinically with Budapest criteria while actively excluding focal nerve injury, infection, vascular disease, fracture complications, and inflammatory arthropathy. Prioritize early functional restoration; reserve medications, blocks, and neuromodulation for barriers to rehabilitation or persistent disabling pain.

**Clinical question:** How should clinicians confirm CRPS, exclude competing diagnoses, and sequence rehabilitation, pharmacotherapy, and neuromodulation?

Updated: 2026-08-24T17:52:43.645367+00:00

## What matters in practice
- CRPS is a clinical diagnosis: apply Budapest clinical criteria and require that no alternative diagnosis better explains the presentation. [1][8][13]
- Examine and document both limbs during the same visit; Budapest criteria require symptoms in at least three of four domains and signs in at least two domains. [8][21]
- A distribution confined to a named peripheral nerve, particularly with electrophysiologic evidence of nerve injury, favors peripheral nerve injury over CRPS; CRPS findings are typically regionally distributed and distal. [24]
- Begin physical or occupational therapy directed at range of motion and functional use early; graded motor imagery and mirror therapy are reasonable components of a rehabilitation plan. [1][13]
- No FDA-approved pharmacologic treatment exists for CRPS; use drug and procedural interventions as adjuncts to restore function rather than as stand-alone care. [14]
- For refractory disabling CRPS despite rehabilitation-centered multimodal care, spinal cord stimulation with physical therapy has randomized-trial evidence of pain relief from 6 months through 2 years. [18]

## Confirm CRPS with Budapest clinical criteria

Do not use imaging, thermography, or laboratory testing as a substitute for a documented clinical examination.

Establish CRPS only when there is continuing pain disproportionate to any inciting event; the patient reports at least one symptom in three of four domains; the examiner identifies at least one sign in two or more domains; and no competing diagnosis better accounts for the findings. The four domains are sensory, vasomotor, sudomotor/edema, and motor/trophic. [8][13]

Elicit symptoms separately from observed signs. Sensory symptoms are hyperesthesia or allodynia; vasomotor symptoms are temperature asymmetry or skin-color change/asymmetry; sudomotor/edema symptoms are edema, sweating change, or sweating asymmetry; motor/trophic symptoms are reduced range of motion, motor dysfunction, or trophic skin, hair, or nail change. At examination, document corresponding objective asymmetry in the affected and contralateral limbs. [8][21]

Use the clinical rather than research Budapest criteria for routine care. Reported validation estimates for the clinical criteria are sensitivity 0.99 and specificity 0.68; therefore, a positive assessment should trigger a deliberate search for mimics rather than automatic diagnostic closure. [3][21]
- Record the inciting event, limb involved, pain distribution, laterality, temperature/color comparison, edema, sweating asymmetry, active range of motion, motor performance, and trophic findings at baseline. [8][21]
- Classify CRPS type II only when there is a documented peripheral nerve injury; otherwise use type I. A nerve-territory sensory deficit with accessible-nerve electrophysiologic confirmation supports peripheral nerve injury. [24]
- Do not diagnose CRPS solely from disproportionate pain after fracture, surgery, or sprain; these are common triggers but do not satisfy the complete clinical criteria. [1][8][14]

*Budapest clinical criteria require the elements shown; signs must be present on physician examination. [8][21]*

| Required element | Clinical action | Qualifying findings |
| --- | --- | --- |
| Pain requirement | Confirm continuing regional pain disproportionate to the inciting event. | Persistent pain out of proportion to the injury. [8] |
| Patient-reported symptoms | Document at least one symptom in at least 3 of 4 domains. | Sensory; vasomotor; sudomotor/edema; motor/trophic symptoms. [8] |
| Observed signs | Elicit and document at least one sign in at least 2 of 4 domains at the evaluation. | Hyperalgesia/allodynia; temperature or color asymmetry; edema or sweating asymmetry; reduced motion, motor dysfunction, or trophic change. [8][21] |
| Diagnostic exclusion | Pursue an alternate diagnosis when it better explains pain or objective findings. | CRPS remains a clinical diagnosis after excluding alternative causes. [13] |

## Exclude conditions that change immediate treatment

Testing is indication-driven: choose studies to identify an alternative structural, neurologic, vascular, or inflammatory explanation.

Start with a focused history and examination for fracture complications, postoperative infection, focal peripheral nerve injury, vascular pathology, inflammatory joint disease, and severe or progressive neurologic deficits. Imaging or other diagnostic testing should be obtained when examination or history suggests a serious underlying condition or progressive neurologic deficit, not to confirm CRPS in isolation. [15]

Differentiate focal peripheral nerve injury from CRPS before labeling type II disease. Peripheral nerve injury is supported by a lesion history, somatosensory abnormalities within the injured nerve territory, and—when the nerve is accessible—electrophysiologic evidence of nerve damage. In contrast, CRPS commonly has generalized distal, regional findings that extend beyond a single named nerve territory. [24]

The clinical phenotype may evolve. Early "warm" CRPS is described as inflammation-predominant, whereas chronic "cold" CRPS is more autonomic-feature predominant; this pattern can help frame serial examinations but does not replace Budapest criteria or exclusion of mimics. [1]
- Obtain plain radiography or other structural imaging when recurrent trauma, fracture nonunion, hardware complication, or another osseous/soft-tissue cause is clinically suspected; do not order imaging routinely for a typical Budapest-positive presentation. [15]
- Order electrodiagnostic testing when symptoms and sensory deficits are anatomically concordant with a potentially injured peripheral nerve and the result would alter classification or management. [24]
- Use quantitative sensory testing, autonomic tests, thermography, or bone scintigraphy only as adjunctive assessments when the clinical question remains unresolved; CRPS diagnosis is clinical. [1][13][21][22]

### When to escalate diagnostic evaluation

Escalate promptly when the pain pattern is focal rather than regional, objective findings are absent or nonreproducible, neurologic deficits are severe or progressive, or a structural or systemic disease better accounts for the syndrome. In complex pain syndromes, pain-specialist consultation can assist with diagnostic confirmation and management planning. [15]

*Clinical patterns that redirect the differential and next test. [15][24]*

| Pattern | Most consequential alternative | Next action |
| --- | --- | --- |
| Symptoms and sensory loss map to one named nerve territory | Peripheral nerve injury | Review injury mechanism and obtain electrodiagnostic testing when the nerve is accessible and the result will change management. [24] |
| Regional distal limb abnormalities across sensory, autonomic, edema, motor, or trophic domains | CRPS | Apply Budapest criteria and document contralateral comparison; exclude a better explanation. [8][21] |
| Severe or progressive neurologic deficits or concern for serious underlying disease | Structural or neurologic pathology | Obtain targeted imaging or diagnostic testing based on the suspected disorder. [15] |
| Post-traumatic pain without required signs and symptoms | Injury-related pain or another local complication | Reassess the injury and competing diagnosis rather than assigning CRPS. [1][8] |

## Make functional restoration the treatment anchor

Initiate rehabilitation early once urgent alternative pathology has been addressed.

Refer for physical therapy and, when upper-extremity activities or self-care are impaired, occupational therapy with explicit goals for active range of motion, limb use, and progressive function. Manual therapy and exercise are associated with improved range of motion and function and reduced disability; therapy should be integrated with pain management rather than deferred until pain resolves. [13]

Include graded motor imagery or mirror therapy when pain, allodynia, movement avoidance, or body-perception disturbance limits limb engagement. These approaches are among nonpharmacologic interventions used within CRPS rehabilitation, and randomized-trial reviews cited in a state-of-the-art review support physical/occupational therapy including graded motor imagery and mirror therapy. [1][13]

Assess function, work demands, sleep, psychosocial stressors, and behavioral factors at each treatment decision because these factors affect pain-treatment selection and rehabilitation participation. Psychological support should be incorporated when distress, fear, or other behavioral barriers interfere with recovery; it is not evidence that symptoms are psychogenic. [13][15]
- Set a measurable therapy target at each visit, such as active motion, tolerated loading, use of the limb in a defined activity, or return to a specific work/self-care task. [13][15]
- Use adjunctive modalities—including transcutaneous electrical nerve stimulation, ultrasound, laser therapy, pain education, mirror therapy, and graded motor imagery—only in a plan that maintains active functional progression. [13]
- Reassess for an alternative diagnosis if function deteriorates despite an apparently concordant rehabilitation plan or if new focal neurologic findings emerge. [15][24]

*Rehabilitation-centered care components and their practical role. [1][13][15]*

| Intervention | Use when | Operational goal |
| --- | --- | --- |
| Physical therapy | Range of motion, gait, loading, or generalized limb function is impaired. | Progress active movement and functional use. [13] |
| Occupational therapy | Upper-extremity function, activities of daily living, or work tasks are limited. | Restore task-specific limb use and independence. [1][13] |
| Graded motor imagery or mirror therapy | Pain or allodynia limits engagement with the affected limb. | Support progressive functional participation as part of therapy. [1][13] |
| Psychological support | Psychosocial stressors, sleep disturbance, or behavioral barriers compromise pain care or rehabilitation. | Address modifiable barriers while maintaining rehabilitation goals. [13][15] |

## Select medications and procedures to remove barriers to rehabilitation

No pharmacologic treatment is FDA-approved specifically for CRPS.

Drug selection should be individualized to the dominant barrier—such as inflammatory features, neuropathic pain, sleep disruption, or inability to participate in therapy—and reviewed against functional benefit rather than pain score alone. Agents used in CRPS care include nonsteroidal anti-inflammatory drugs, anticonvulsants, and corticosteroids, but the evidence base is limited and there are no FDA-approved pharmacologic treatments for CRPS. [13][14]

In early inflammation-predominant disease, oral corticosteroids have supportive randomized-trial review evidence, but the provided literature does not establish a regimen. Prescribe only after weighing infection, glycemic, psychiatric, bone, and other patient-specific corticosteroid risks, and define a short-interval reassessment of function and adverse effects. [1][11]

Bisphosphonates, calcitonin, subanesthetic intravenous ketamine, and free-radical scavengers have been reported as potentially effective in randomized-trial reviews, but treatment selection should be made by clinicians experienced with CRPS and the agent-specific safety profile. Do not infer an FDA indication, standardized dose, or universal sequencing from these data. [1][14]
- Consider a sympathetic block only for selected patients when conservative management is insufficient and a time-limited reduction in pain is expected to facilitate rehabilitation; reassess function after the procedure before repeating it. [13]
- Avoid treating long-term opioid therapy as the core CRPS strategy. If opioids are considered for pain, follow patient-specific assessment principles and integrate them into a comprehensive plan with nonpharmacologic treatment. [15]
- Low-dose naltrexone remains investigational for CRPS; its presence in an active clinical trial is not evidence for routine clinical use. [16]

### When to refer for interventional care

Refer to an interventional pain specialist when disabling pain persists despite a rehabilitation-centered multimodal plan, when a block is being considered to enable therapy, or when neuromodulation is under consideration. Interventional pain specialists can provide neurostimulation and other procedures, although procedure-specific evidence and risk vary. [15]

*Adjunctive options should be selected for a functional purpose rather than used in place of rehabilitation. [1][13][14][15]*

| Option | Potential role | Key limitation or decision rule |
| --- | --- | --- |
| NSAIDs, anticonvulsants, corticosteroids | Medication adjuncts in multimodal care. [13] | No FDA-approved pharmacologic therapy exists for CRPS; reassess for functional benefit. [14] |
| Bisphosphonates, calcitonin, IV ketamine, free-radical scavengers | Potential options in selected patients based on limited trial evidence. [1] | Use specialist-led, patient-specific risk-benefit assessment; no standardized regimen is established here. [1][14] |
| Sympathetic block | Selected patients whose pain prevents rehabilitation. [13] | Use the post-procedure ability to advance function as the continuation criterion. [13] |
| Opioids | May be part of an individualized analgesic regimen. [14][15] | Do not use as a substitute for diagnosis, functional restoration, and comprehensive pain care. [15] |

## Consider neuromodulation for persistent disabling CRPS

Escalate after reassessing diagnosis, rehabilitation barriers, and the patient’s functional goals.

For persistent disabling CRPS after conservative multidisciplinary care, discuss spinal cord stimulation as an adjunct to—not a replacement for—physical therapy. An ASA/ASRA guideline cites one randomized controlled trial in which spinal cord stimulation plus physical therapy provided effective pain relief compared with physical therapy alone from 6 months through 2 years. [18]

Dorsal root ganglion stimulation is another neuromodulation approach for CRPS and causalgia. Comparative evidence summarized in a 2024 report found higher treatment success with dorsal root ganglion stimulation at 3 and 12 months; selection should account for pain distribution, procedural candidacy, patient goals, and local expertise. [2]

Continue to measure disability and function after implantation rather than defining success only by analgesia. Neuromodulation is reasonable only when the expected improvement justifies device-related procedural burden and the patient can continue active rehabilitation. [15][18]
- Before neuromodulation referral, reconfirm the clinical diagnosis and exclude a focal nerve lesion or other treatable structural diagnosis. [13][15][24]
- Use a pain specialist for selection among neuromodulation, blocks, and other invasive options because benefits and risks differ by procedure. [15]
- Do not extrapolate benefit from spinal cord stimulation to routine early CRPS or to patients who have not received rehabilitation-centered care. [18]

*Escalation options for refractory CRPS. [2][15][18]*

| Intervention | Appropriate setting | Evidence signal |
| --- | --- | --- |
| Spinal cord stimulation plus physical therapy | Persistent disabling CRPS after conservative rehabilitation-centered care. | One randomized controlled trial reported effective pain relief at 6 months through 2 years versus physical therapy alone. [18] |
| Dorsal root ganglion stimulation | Selected CRPS or causalgia patients being evaluated for neuromodulation. | Higher treatment success at 3 and 12 months in comparative evidence summarized in 2024. [2] |
| Sympathetic block | Selected patients when conservative care is insufficient and pain limits rehabilitation. | May benefit selected individuals; evaluate whether it enables functional progression. [13] |

## Track function and reassess the diagnosis when trajectory is discordant

Use serial exams to detect changing phenotype, emerging mimics, and rehabilitation response.

At follow-up, repeat the bilateral assessment of pain distribution, allodynia or hyperalgesia, temperature and color asymmetry, edema or sweating asymmetry, range of motion, motor performance, and trophic change. A transition from warm inflammatory features to cold autonomic features has been described as CRPS becomes chronic, but new focal deficits should prompt renewed evaluation for peripheral nerve or structural disease. [1][24]

Counsel that outcomes are heterogeneous: many cases resolve within the first year, while a smaller subgroup progresses to chronic CRPS with persistent pain and disability. Early diagnosis and treatment are associated with improved outcomes, supporting prompt rehabilitation rather than prolonged observation while awaiting a confirmatory test. [1][13]

Document treatment response using functional endpoints: limb use, active range of motion, activity tolerance, work demands, sleep, and ability to participate in prescribed therapy. If these measures do not improve, revisit the diagnosis, treatment adherence, psychosocial barriers, and whether an interventional strategy could meaningfully enable rehabilitation. [15]
- Reassess sooner when there is worsening pain with new neurologic deficit, a change from regional to focal anatomic distribution, or concern for an alternative serious condition. [15][24]
- Use persistent inability to progress in therapy—not pain intensity alone—as a trigger to reconsider medication, block, or neuromodulation referral. [13][15][18]
- Maintain multidisciplinary care for chronic disability because effective management of chronic CRPS is often challenging and trial evidence for commonly used interventions is limited. [1]

*Follow-up domains that should drive treatment modification. [1][15][24]*

| Domain | What to document | Action if discordant |
| --- | --- | --- |
| Clinical signs | Bilateral sensory, vasomotor, sudomotor/edema, and motor/trophic findings. [8] | New focal or progressive neurologic findings warrant targeted reevaluation. [15][24] |
| Function | Range of motion, limb use, activity tolerance, work and self-care capacity. [13][15] | If function stalls, identify barriers and revise the rehabilitation-centered plan. [13][15] |
| Pain phenotype | Inflammatory-predominant warm versus autonomic-predominant cold features. [1] | Use phenotype to guide reassessment, not as a replacement for diagnostic criteria. [1][8] |
| Treatment burden | Adverse effects, procedural burden, and ability to continue therapy. [15] | Stop or modify adjuncts that do not enable meaningful functional gain. [15] |

## References
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## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.