High-yield overview
The Suicide Disease
Vit CPrevention
PainDisproportionate
MoveTherapy
BlockDiagnostic
Types
CRPS Type I
PatternNo identifiable nerve injury (Reflex Sympathetic Dystrophy).
Treatment
CRPS Type II
PatternIdentifiable nerve injury (Causalgia).
Treatment
Warm vs Cold
PatternEarly (Warm) vs Late (Cold/Atrophic).
Treatment
Critical Must-Knows
- Diagnosis is CLINICAL, based on the Budapest Criteria.
- Pain is disproportionate to the inciting event.
- Vitamin C (500mg daily for 50 days) prevents CRPS after distal radius fractures.
- Surgery is CONTRAINDICATED in the active phase.
Clinical Pearls
- "Triple Phase Bone Scan shows diffuse uptake in late phase.
- "Stellate Ganglion Block is both diagnostic and therapeutic.
- "Early mobilization is the cornerstone of treatment.
Clinical Imaging
Imaging Gallery
Do Not Operate
Surgical Trap
Active CRPS is a "No Fly Zone" Performing elective surgery (e.g. carpal tunnel release, trigger finger) on a hand with active CRPS will cause a massive flare-up. Delay all surgery until the CRPS is "quiescent" (usually greater than 12 months).
Tourniquet Risk
Reperfusion Injury Prolonged tourniquet time increases ischemia-reperfusion injury and free radical release, which drives CRPS. Minimize tourniquet time and use Vitamin C.
| Feature | CRPS Type I | CRPS Type II |
|---|---|---|
| Old Name | Reflex Sympathetic Dystrophy (RSD) | Causalgia |
| Nerve Injury | Absent (or minor) | Present (Major nerve) |
| Inciting Event | Fracture, Crush, Sprain | Nerve Transection/Injection |
| Symptoms | Identical | Identical |
Mnemonic
STAMPBudapest Clinical Categories
| S | Sensory Hyperalgesia, Allodynia. |
| T | Trophic/Motor Weakness, Tremor, Hair/Nail changes. |
| A | Autonomic Sweating (Sudomotor), Color (Vasomotor). |
| M | Motor Reduced range of motion. |
| P | Pain Disproportionate pain. |
| S | Sensory Hyperalgesia, Allodynia. | M | Motor Reduced range of motion. |
| T | Trophic/Motor Weakness, Tremor, Hair/Nail changes. | P | Pain Disproportionate pain. |
| A | Autonomic Sweating (Sudomotor), Color (Vasomotor). |
Hook:STAMP out CRPS.
Mnemonic
VPT-SIMTreatment Ladder
| V | Vitamin C Prevention. |
| P | Physical Therapy Desensitization, Stress Loading. |
| T | Topical DMSO, Capsaicin. |
| S | Sympathetic Blocks. |
| I | Implant Spinal Cord Stimulator. |
| M | Meds Gabapentin, Bisphosphonates. |
| V | Vitamin C Prevention. | T | Topical DMSO, Capsaicin. | I | Implant Spinal Cord Stimulator. |
| P | Physical Therapy Desensitization, Stress Loading. | S | Sympathetic Blocks. | M | Meds Gabapentin, Bisphosphonates. |
Hook:Very Painful Treatment SIMulation.
Mnemonic
FEMALERisk Factors
| F | Female 3:1 ratio. |
| E | Event Fracture or Trauma. |
| M | Middle age 50-70 years. |
| A | Anxious Psychological predisposition. |
| L | Limb Upper limb more than lower limb. |
| E | External Tight casts. |
| F | Female 3:1 ratio. | M | Middle age 50-70 years. | L | Limb Upper limb more than lower limb. |
| E | Event Fracture or Trauma. | A | Anxious Psychological predisposition. | E | External Tight casts. |
Hook:Female predispositon.
Overview
Definition
Complex Regional Pain Syndrome (CRPS): A chronic pain condition characterized by spontaneous or evoked pain that is disproportionate in time or degree to the usual course of any known trauma.
It typically affects one limb (usually upper) after an injury. The exact mechanism involves peripheral inflammation, sympathetic coupling, and central sensitization (neuroplasticity).
Pathophysiology
Peripheral Mechanisms
- Neurogenic Inflammation: Release of CGRP and Substance P leads to vasodilation ("Warm Phase") and plasma extravasation (Edema).
- Sympathetic Coupling: Alpha-adrenergic receptors are expressed on nociceptors. Circulating catecholamines (stress) trigger pain.
This explains why stress exacerbates the condition.
Classification
IASP Classification
- Type I (RSD): Developing after an initiating noxious event that is NOT limited to the distribution of a single peripheral nerve.
- Type II (Causalgia): Developing after a nerve injury.
- NOS (Not Otherwise Specified): Partially meets criteria.
This catch-all category allows for treatment without full diagnostic certainty.
Clinical Assessment
To diagnose CRPS, the patient must meet ALL of the following Budapest Criteria:
1. Continuing Pain: Disproportionate to inciting event. 2. Symptom Report: Must report at least ONE symptom in THREE of the four categories:
- Sensory: Hyperesthesia, Allodynia.
- Vasomotor: Temperature asymmetry, Skin color changes.
- Sudomotor/Edema: Sweating changes, Edema.
- Motor/Trophic: Decreased ROM, Weakness, Hair/Nail/Skin changes. 3. Examination Sign: Must display at least ONE sign in TWO of the four categories at time of evaluation. 4. Exclusion: No other diagnosis better explains the signs and symptoms.
Note: The Budapest clinical criteria are sensitive (0.99) with markedly improved specificity (0.68) over the older IASP criteria (0.41); the stricter Budapest research criteria reach specificity 0.79 (Harden et al., Pain 2010).
Algorithm
Differential Diagnosis
CRPS is a diagnosis of exclusion (Budapest criterion 4). Actively rule out the following before committing to the label:
| Condition | Distinguishing Features | Discriminating Test |
|---|---|---|
| Deep vein thrombosis | Unilateral swelling, calf/forearm tenderness, no allodynia | Doppler ultrasound, D-dimer |
| Cellulitis / infection | Fever, raised inflammatory markers, well-demarcated erythema | Bloods (CRP/WCC), aspirate if effusion |
| Compartment syndrome | Pain on passive stretch, tense compartment, acute post-injury | Compartment pressures - surgical emergency |
| Peripheral neuropathy / nerve entrapment | Pain in defined nerve territory, motor/sensory deficit fits a nerve | Nerve conduction studies / EMG |
| Inflammatory arthritis | Symmetrical joint involvement, synovitis, serology positive | RF/anti-CCP, ESR, joint exam |
| Vascular disease / Raynaud | Episodic colour change, ischaemic features, pulse changes | Vascular studies, angiography |
| Factitious / self-harm | Sharp demarcation lines, inconsistent history | Diagnosis of exclusion, observation |
Investigations
Triple Phase Bone Scan (Technetium-99)
- Phase 1 (Flow): Asymmetric blood flow (increased).
- Phase 2 (Pool): Soft tissue uptake.
- Phase 3 (Delayed): Diffuse peri-articular uptake in all joints of the hand/wrist.
- Sensitivity: High (greater than 90%) in Stage 1/2.
This is the gold standard for early diagnosis.
Management
Algorithm
1. Prevention (The Best Cure)
- Vitamin C: 500mg daily for 50 days (Zollinger et al.) for all distal radius fractures.
- Pain Control: Aggressive acute pain management reduces central sensitization.
- No Tight Casts: Avoid constriction.
Every wrist fracture patient gets a verbal and written instruction for Vitamin C.
Surgical Interventions
Surgery is rarely indicated and often harmful.
Indications for Surgery
- Identifyable Nerve Lesion: E.g., neuroma or compression that is driving the CRPS (Type II).
- Contractures: Only in "Cold/Burned Out" phase (Stage 3).
A 'painful nerve' is different from 'CRPS'. Fixing the nerve may fix the CRPS.
Therapy Details
Stress Loading (Watson):
- Scrubbing: Patient moves a scrub brush back and forth on a table with weight bearing.
- Carrying: Patient carries a weighted bag in the hand throughout the day.
- Mechanism: Provides proprioceptive input without painful joint motion.
Mirror Therapy (Ramachandran):
- Place unaffected hand in front of mirror.
- Hide affected hand behind mirror.
- Move unaffected hand and watch reflection ("Tricks brain" into thinking the bad hand is moving pain-free).
Complications
Musculoskeletal Complications
| Complication | Frequency | Mechanism | Management |
|---|---|---|---|
| Joint Contractures | Very common | Disuse, fibrosis | Aggressive hand therapy, serial splinting |
| Finger Stiffness | 40-60% | Capsular fibrosis | ROM exercises, dynamic splinting |
| Wrist Ankylosis | 10-20% severe cases | Spontaneous fusion | May require salvage procedures |
| Osteoporosis | Nearly universal | Disuse atrophy | Weight bearing, bisphosphonates |
| Muscle Atrophy | Common | Disuse, neurogenic | Strengthening when pain controlled |
Trophic Changes
| Change | Features | Reversibility |
|---|---|---|
| Skin | Shiny, thin, atrophic | Partially reversible |
| Hair | Increased then decreased growth | Variable |
| Nails | Brittle, ridged, dystrophic | Usually improves |
| Subcutaneous Tissue | Oedema then atrophy | Often permanent changes |
Psychological Complications
- Depression: Affects 40-50% of CRPS patients. Screen and treat early.
- Anxiety: Very common with chronic pain. CBT beneficial.
- Sleep Disturbance: Pain disrupts sleep, worsening symptoms.
- Suicide Risk: CRPS called "The Suicide Disease" - actively assess and refer.
- Catastrophizing: Worsens outcomes. Address with psychological therapy.
Functional Disability
- Work Disability: 30-50% unable to return to previous work
- ADL Impairment: May affect dressing, eating, grooming
- Social Isolation: Pain and dysfunction lead to withdrawal
- Quality of Life: Significantly reduced without treatment
Postoperative Care
Acute Phase Management
- Pain Control: Multimodal analgesia, avoid opioid dependence
- Oedema Control: Elevation, compression, contrast baths
- Protected Motion: Early active ROM within pain tolerance
- Vitamin C: 500-1000mg daily for 50 days post any procedure
Rehabilitation Phases
Phase 1
- Identify and document triggers
- Desensitization techniques (textures, temperatures)
- Start Vitamin C immediately
- Refer to specialised Hand Therapy
- Mirror therapy initiation
Phase 2
- If pain controlled, aggressive active ROM
- Avoid passive stretching (provokes pain flares)
- Progressive loading and strengthening
- Stress loading program (scrub and carry)
- Continue mirror therapy
Phase 3
- Functional task training
- Work simulation activities
- Graded exposure to avoided tasks
- Vocational rehabilitation assessment
Long Term
- Life-long tendency for recurrence with new injuries
- Prophylactic Vitamin C for any future surgeries
- Self-management strategies
- Flare management plan
Red Flags Requiring Reassessment
- Increasing Pain Despite Treatment: Consider alternative diagnosis
- New Neurological Symptoms: May indicate central sensitisation
- Psychiatric Deterioration: Urgent mental health referral
- Spread of Symptoms: May indicate generalised CRPS
Prognosis
Prognostic Factors
| Factor | Better Prognosis | Worse Prognosis |
|---|---|---|
| Age | Children, young adults | Elderly |
| Duration at Treatment | Less than 3 months | Greater than 1 year |
| CRPS Type | Warm CRPS (early) | Cold CRPS (established) |
| Extent | Localised | Spreading to multiple limbs |
| Psychological Status | Minimal catastrophising | Depression, PTSD, anxiety |
| Treatment Response | Early response to therapy | Refractory to interventions |
Expected Outcomes
- Full Recovery: 10-30% (more in children)
- Significant Improvement: 40-60%
- Chronic Symptoms: 30-40%
- Severe Disability: 10-15%
Key Points for Outcome
- Early Diagnosis and Treatment: Single most important prognostic factor
- Children: Better prognosis than adults, higher recovery rates
- Warm CRPS: Better response to sympatholytics and early intervention
- Delayed Treatment: Poor prognosis - treatment started within 3 months has significantly better outcomes
- Multidisciplinary Approach: Improves outcomes across all patient groups
- Recurrence: Can recur in same or opposite limb.
Controversies & Areas of Uncertainty
Vitamin C - how strong?
The Zollinger RCTs support 500mg for 50 days after wrist fracture, but later trials and meta-analyses have been heterogeneous. It remains cheap and low-risk, so many units still prescribe it while UK guidance treats it as optional rather than mandatory.
Sympathetic blocks
A diagnostic stellate block can separate sympathetically maintained from independent pain, but high-quality evidence for durable therapeutic benefit is limited and inconsistent. Response does not reliably predict long-term outcome.
Does early surgery cause CRPS?
Active CRPS is a relative contraindication to elective hand surgery, yet a genuine surgically treatable driver (e.g. nerve compression in Type II) can warrant intervention. Distinguishing "painful nerve" from "CRPS" is the crux.
Staging model
The classic three-stage (warm/dystrophic/atrophic) sequence is historically useful but not validated as a fixed temporal progression; many patients do not follow it. Warm versus cold phenotype is more clinically useful than rigid staging.
Evidence Base
Budapest Criteria Validation
Harden et al. • Pain (2010)
Key Findings:
- Validation study in 113 CRPS-I and 47 non-CRPS neuropathic pain patients
- Budapest clinical criteria: sensitivity 0.99, specificity 0.68 (vs IASP specificity 0.41)
- Budapest research criteria gave the highest specificity (0.79)
Clinical Implication: The Budapest Criteria are the validated clinical diagnostic standard for CRPS.
Vitamin C Prophylaxis (Index RCT)
Zollinger et al. • Lancet (1999)
Key Findings:
- Double-blind RCT, 123 adults with 127 conservatively treated wrist fractures
- 500mg vitamin C daily for 50 days reduced RSD/CRPS from 22 percent (placebo) to 7 percent
- Proposed mechanism: antioxidant scavenging of toxic oxygen free radicals
Clinical Implication: First randomised evidence supporting vitamin C prophylaxis after wrist fracture.
Vitamin C Dose-Response Trial
Zollinger et al. • J Bone Joint Surg Am (2007)
Key Findings:
- Multicentre double-blind RCT, 416 patients with 427 wrist fractures (placebo vs 200/500/1500mg)
- CRPS prevalence 2.4 percent with vitamin C vs 10.1 percent with placebo
- 500mg and 1500mg equally effective (relative risk 0.17); 500mg for 50 days recommended
Clinical Implication: Confirms 500mg daily for 50 days as the optimal prophylactic dose.
Bisphosphonate (Neridronate) RCT
Varenna et al. • Rheumatology (Oxford) (2013)
Key Findings:
- Multicentre double-blind placebo-controlled RCT, 82 patients with acute CRPS-I
- Four IV neridronate 100mg infusions over 10 days gave significant, persistent VAS reduction
- Authors conclude bisphosphonates are a treatment of choice in early CRPS-I
Clinical Implication: Strongest evidence base for bisphosphonates in acute CRPS with high bone-scan uptake.
Mirror Visual Feedback
McCabe et al. • Rheumatology (Oxford) (2003)
Key Findings:
- Controlled pilot study, 8 subjects with CRPS Type 1
- Mirror visual feedback gave analgesia in early CRPS (under 8 weeks) but no benefit in chronic disease
- Supports the motor-sensory incongruence model of CRPS pain
Clinical Implication: Low-risk early intervention; diminishing benefit once disease is chronic.
Graded Motor Imagery RCT
Moseley • Neurology (2006)
Key Findings:
- RCT of 51 patients with CRPS-I or phantom limb pain
- Graded motor imagery (laterality recognition to imagined movement to mirror therapy) reduced VAS by 23mm vs 10mm control
- Functional gains maintained at 6-month follow-up
Clinical Implication: Structured graded motor imagery outperforms standard care and avoids painful limb movement.
Spinal Cord Stimulation RCT
Kemler et al. • N Engl J Med (2000)
Key Findings:
- RCT of 54 patients with chronic RSD/CRPS (36 SCS plus physiotherapy vs 18 physiotherapy alone)
- Mean pain reduction 2.4cm vs 0.2cm increase at 6 months (less than 0.001)
- No improvement in functional status; 6 of 24 implanted patients had complications
Clinical Implication: Landmark RCT supporting SCS for refractory CRPS - pain relief without functional gain.
Ketamine Infusions
Schwartzman et al. • Pain (2009)
Key Findings:
- Double-blind placebo-controlled RCT of outpatient IV ketamine over 10 days
- Statistically significant reduction across multiple pain parameters versus placebo
- NMDA-receptor antagonist mechanism; warrants larger higher-dose trials
Clinical Implication: Option for refractory CRPS in specialist pain settings.
Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
CLINICAL SCENARIOStandard
Scenario 1: The Swollen Hand
CLINICAL PROMPT
"A 50-year-old female presents 6 weeks after a distal radius fracture (treated in a cast). She complains the cast was 'too tight'. The cast is off. Her hand is swollen, red, sweating, and she cannot make a fist due to pain."
PRACTICAL APPROACH
This is classic CRPS Type 1 (Acute/Warm phase). My assessment would follow the Budapest Criteria (Sensory, Vasomotor, Sudomotor, Motor signs). I would rule out infection or unrecognized tendon rupture. Treatment is multidisciplinary: 1. Prevention (start Vit C 500mg). 2. Therapy (Desensitization, Edema control, Stress loading). 3. Pharmacotherapy (Gabapentin, NSAIDs, Prednisolone boost). 4. Referral to Pain Specialist for consideration of Stellate Ganglion Block. I would NOT operate.
KEY CLINICAL POINTS
Recognize Acute CRPS
Budapest Criteria
Multimodal treatment
Avoid Surgery
COMMON PITFALLS
Operating (e.g. releasing a 'tight' carpal tunnel) - will manifest disaster
Dismissing as 'low pain threshold'
FURTHER QUESTIONS
"What is the role of Bone Scan?"
"It supports the diagnosis. Phase 3 shows diffuse peri-articular uptake. Sensitivity greater than 90% in this stage."
CLINICAL SCENARIOStandard
Scenario 2: Chronic Neuropathic Pain
CLINICAL PROMPT
"A patient with old nerve injury has a cold, stiff, blue hand with severe pain. It has been 2 years."
PRACTICAL APPROACH
This represents Chronic/Cold phase CRPS (Stage 3). The prognosis is poorer. Treatment focuses on function and pain management rather than 'cure'. I would involve the chronic pain team for spinal cord stimulation or ketamine infusions. Therapy focuses on maintaining remaining ROM. Joint contractures may require release but only if the active CRPS is burned out, which is risky.
KEY CLINICAL POINTS
Stage 3 identification
Poorer prognosis
Spinal Cord Stimulation
COMMON PITFALLS
Promising cure
Aggressive surgery
FURTHER QUESTIONS
"Are Sympathectomies useful here?"
"Rarely. In the cold phase, the pain is often Sympathetically Independent (Centralized)."
CLINICAL SCENARIOStandard
Scenario 3: Prevention
CLINICAL PROMPT
"You are fixing a distal radius fracture. The patient asks how to prevent 'that horrible pain syndrome'."
PRACTICAL APPROACH
I would counsel her on three things: 1. Vitamin C (500mg daily for 50 days) - Level 1 evidence. 2. Early mobilization of fingers - 'Move it or lose it'. 3. Adequate pain control post-op to prevent central wind-up. I typically use a regional block (Axillary) which provides a 'pain holiday' and may reduce sympathetic drive acutely.
KEY CLINICAL POINTS
Vitamin C protocol
Early motion
Regional Anesthesia
COMMON PITFALLS
Forgetting Vitamin C dose (500mg)
FURTHER QUESTIONS
"Does the block prevent CRPS?"
"Evidence is mixed, but it facilitates early pain-free movement, which prevents CRPS."
MCQ Practice Points
Diagnosis
Q: What is the most sensitive imaging modality for early CRPS? A: Triple Phase Bone Scan (Phase 3 diffuse uptake).
Phases
Q: Is the hand warm or cold in acute CRPS? A: Warm (Vasodilation due to neurogenic inflammation). It becomes cold later.
Prevention
Q: What is the recommended dose of Vitamin C for prophylaxis? A: 500mg daily for 50 days.
Treatment
Q: What is the role of Stellate Ganglion Block in CRPS? A: Both diagnostic (confirms Sympathetically Maintained Pain if pain relieved) and therapeutic (series of 3-5 blocks may provide lasting relief).
Classification
Q: What is the difference between CRPS Type I and Type II? A: Type I (RSD) has no identifiable nerve injury. Type II (Causalgia) has an identifiable nerve injury.
Red Flag
Q: When is surgery contraindicated in CRPS? A: During the active phase - surgery will cause a massive flare-up. Wait until quiescent (usually over 12 months).
Guidelines, Registries & Global Practice
Global Epidemiology
- Incidence: Population-based estimates range from approximately 5 to 26 per 100,000 person-years, with the upper end from a Dutch cohort and the lower end from a US (Olmsted County) cohort.
- Demographics: Female predominance (roughly 3 to 4:1); peak onset in the post-menopausal range (around 50 to 70 years). Upper limb is affected more often than lower limb.
- Commonest trigger: Distal radius fracture is the single most frequent inciting event; CRPS may also follow crush, sprain, surgery or immobilisation.
Side-by-Side Guidance
| Body (Region) | Diagnostic Standard | Key Treatment Emphasis |
|---|---|---|
| IASP / Budapest (International) | Budapest clinical criteria for diagnosis | Clinical diagnosis; exclude mimics |
| Royal College of Physicians / BOA (UK) | Budapest criteria; "four pillars" model | Early, function-focused multidisciplinary rehab; vitamin C debated, not mandated |
| Dutch (CBO) Guideline | Budapest criteria | Free-radical scavengers (DMSO, NAC); physiotherapy; pain pathway |
| ANZCA / Faculty of Pain Medicine (Aust/NZ) | Budapest criteria | Multidisciplinary, early mobilisation, psychological input |
Areas of Genuine Difference
- Vitamin C prophylaxis: Endorsed by several orthopaedic/trauma groups after distal radius fracture (Zollinger RCTs), but UK guidance treats it as optional given heterogeneous later evidence.
- Bisphosphonates: Increasingly recommended in early CRPS-I in European rheumatology practice (neridronate RCTs); used more selectively elsewhere.
- Spinal cord stimulation: Reserved for refractory disease; the Kemler RCT showed pain relief without functional gain, tempering enthusiasm.
High- vs Limited-Resource Practice
- Well-resourced settings: Access to specialist multidisciplinary pain teams, triple-phase bone scan, MRI, sympathetic blocks, neuromodulation and ketamine infusion.
- Limited-resource settings: Diagnosis remains clinical (Budapest criteria need no imaging), and the highest-yield, lowest-cost interventions - early mobilisation, desensitisation, mirror therapy, graded motor imagery, simple analgesia and vitamin C - are widely deliverable and remain the backbone of care.
Clinical summary
Diagnostic Criteria (Budapest)
- •Continuing pain disproportionate to event
- •Sensory: Hyperalgesia/Allodynia
- •Vasomotor: Temp/Color asymmetry
- •Sudomotor/Edema: Sweating/Swelling
- •Motor/Trophic: Weakness/Nail changes
Management Hierarchy
- •1. Vitamin C & Physiotherapy (Stress Loading)
- •2. Pharmacotherapy (Gabapentin/Bisphosphonates)
- •3. Sympathetic Block (Stellate)
- •4. Neuromodulation (SCS)
Don't Forget
- •Vit C 500mg x 50 days (Prevention)
- •NO elective surgery during active CRPS
- •Bone Scan = Diffuse peri-articular uptake
- •Mirror Therapy for central desensitization
- •Horner's confirms stellate block worked