CRPS — Budapest Criteria

Complex Regional Pain Syndrome (CRPS) is a chronic pain condition characterised by severe, disproportionate pain accompanied by sensory, vasomotor, sudomotor, and trophic abnormalities in a limb, typically following an injury or surgical procedure. It is one of the most challenging conditions encountered by the orthopaedic surgeon, both in diagnosis — which is purely clinical — and in management. The Budapest Criteria (2003, revised 2007) provide the internationally accepted diagnostic framework.

• CRPS Type I (reflex sympathetic dystrophy, RSD): no demonstrable nerve lesion; most common (accounts for approximately 90%); typically follows minor trauma, fracture, or surgery; the initiating injury may appear trivial
• CRPS Type II (causalgia): associated with a defined peripheral nerve injury; pain distribution may extend beyond the nerve territory; same clinical features as Type I but with identifiable neural injury
• Incidence: approximately 5–26 per 100,000 population per year; female:male ratio approximately 3–4:1; most commonly affects the distal upper limb (wrist and hand — most common) and distal lower limb; peak incidence 40–70 years; triggered by fracture (most common precipitant), surgery, crush injury, sprain, or immobilisation; Colles fracture is the most commonly associated injury
• Pathophysiology: incompletely understood; proposed mechanisms include: peripheral and central sensitisation of nociceptors; dysregulation of the sympathetic nervous system; neurogenic inflammation (substance P, CGRP); cortical reorganisation; inflammatory cytokine upregulation; no single mechanism explains all features

The Budapest Criteria require all of the following:

• 1. Continuing pain disproportionate to any inciting event
• 2. The patient must report at least one symptom in three of the four following categories
• 3. The clinician must identify at least one sign (on physical examination) in two or more of the four categories
• 4. No other diagnosis better explains the signs and symptoms

• Memory aid for Budapest symptom categories: SVMT — Sensory, Vasomotor, sudoMotor/oedema, Motor/Trophic; symptoms in 3/4 categories + signs in 2/4 categories = Budapest positive CRPS

• Note: the three-phase description is useful conceptually but CRPS does not always progress linearly through these phases; many patients have a mixed or fluctuating presentation rather than a clear progression

• CRPS is a clinical diagnosis — no single investigation confirms or excludes it; investigations are used to support the clinical picture and exclude alternative diagnoses
• Triple-phase bone scintigraphy (technetium-99m MDP): the most useful investigation in CRPS; in the acute phase shows increased periarticular uptake in the affected limb (increased blood flow and bone turnover); sensitivity approximately 50–80%, specificity approximately 85%; most useful in the acute/dystrophic phase; may be normal in atrophic phase or mild early CRPS
• Plain radiographs: periarticular osteopaenia (Sudeck`s atrophy) — mottled or patchy bone loss around the joints; may appear within weeks; not sensitive or specific; late finding
• MRI: bone marrow oedema, soft tissue changes, and periarticular signal change support the diagnosis; useful to exclude other pathology (infection, tumour, inflammatory arthritis)
• Thermography: skin temperature asymmetry >1°C supports vasomotor dysfunction; available in specialist centres; not routinely required
• Bloods: ESR, CRP (usually normal or mildly elevated — elevated levels should prompt consideration of alternative diagnoses); blood cultures if infection suspected
• EMG/NCS: for CRPS Type II — identifies and characterises the peripheral nerve injury; normal in CRPS Type I

CRPS management is multidisciplinary and multimodal. Early recognition and treatment improve outcomes. The three pillars are: pain management, physical and occupational rehabilitation, and psychological support.

• Physiotherapy: the cornerstone of CRPS management; graded motor imagery (GMI) — a three-stage process involving limb laterality recognition, motor imagery, and mirror box therapy; desensitisation techniques (TENS, graded texture contact); functional restoration with graded exposure; aerobic exercise; evidence supports GMI and mirror therapy as effective treatments
• Mirror box therapy: the affected limb is hidden behind a mirror; the patient views the reflection of the unaffected limb moving — the brain perceives this as the affected limb moving; disrupts cortical reorganisation; reduces pain and motor dysfunction; evidence for benefit particularly in CRPS of the hand; introduced by Ramachandran; widely used in CRPS rehabilitation
• Pharmacological management: analgesia (paracetamol, NSAIDs — limited evidence); neuropathic agents (amitriptyline, gabapentin, pregabalin — first-line for neuropathic component); bisphosphonates (alendronate, pamidronate IV) — evidence for significant pain reduction and functional improvement; calcitonin — some evidence; corticosteroids — short course for acute inflammatory phase; ketamine infusions — for refractory severe CRPS in specialist centres
• Bisphosphonates in CRPS: intravenous pamidronate (60 mg single infusion) or alendronate orally have good evidence for pain reduction in CRPS; mechanism — reduction of osteoclast-mediated bone resorption and possibly anti-inflammatory effects; particularly effective in the acute/dystrophic phase when bone scintigraphy shows active uptake; consider in all patients with CRPS with evidence of bone involvement
• Interventional procedures: sympathetic nerve blocks (stellate ganglion block for upper limb; lumbar sympathetic block for lower limb) — short-term benefit in some patients; not predictive of spinal cord stimulator response; intravenous regional anaesthesia (Bier block with guanethidine — limited evidence)
• Spinal cord stimulation (SCS): the most effective interventional treatment for refractory CRPS; electrode placed in the epidural space; randomised controlled trial evidence (Kemler et al.) demonstrates significant reduction in VAS pain scores and improvement in quality of life; indicated after failure of conservative measures; patient must demonstrate response to trial stimulation before permanent implantation; most effective evidence-based procedural treatment for CRPS
• Psychological support: CBT (cognitive behavioural therapy); pain acceptance; management of catastrophising; psychological input is essential in all cases; depression and anxiety are common comorbidities in CRPS

• Prevention of CRPS: vitamin C supplementation (500 mg daily for 50 days) after distal radius fracture and ankle fractures has level 1 evidence for reducing the incidence of CRPS (Zollinger et al. RCT); mechanism — antioxidant reducing free radical-mediated neurogenic inflammation; simple, inexpensive, and should be routinely prescribed following wrist fractures; risk reduction approximately 50%
• Surgery in CRPS: elective surgery should generally be avoided in active CRPS — any further surgical stimulus can exacerbate the condition; if surgery is essential (e.g., for hardware removal or fracture malunion), it should only be performed when CRPS is in remission or well-controlled; aggressive pre-, intra-, and post-operative pain management and immediate physiotherapy are mandatory; a regional anaesthetic technique (nerve block) may reduce perioperative sensitisation
• Distinguishing CRPS from factitious disorder / malingering: CRPS features objective signs (temperature asymmetry measurable by thermography, bone scintigraphy changes, radiological osteopaenia) — these objective findings support an organic diagnosis; however, functional overlay and psychological amplification are common in CRPS; comprehensive psychology assessment is appropriate but CRPS should not be dismissed as psychosomatic; multidisciplinary pain team assessment is the optimal approach
• Graded motor imagery (GMI) programme: three stages — (1) limb laterality recognition (patients view images and identify which limb is depicted; trains cortical representation); (2) explicit motor imagery (imagined movements without actual motion); (3) mirror box therapy (uses visual feedback of the unaffected limb to "train" the affected limb); the programme takes 6–12 weeks; evidence of benefit from randomised trials (Moseley 2004); superior to physiotherapy alone for CRPS of the hand

• Budapest Criteria: disproportionate pain + symptoms in 3/4 categories + signs in 2/4 categories + no other diagnosis; SVMT — Sensory, Vasomotor, sudoMotor/oedema, Motor/Trophic
• Type I: no nerve injury (RSD); Type II: defined nerve injury (causalgia); same clinical features
• Most common precipitant: Colles fracture; most common site: distal upper limb (wrist and hand)
• Triple-phase bone scintigraphy: most useful investigation; periarticular uptake in acute phase; sensitivity 50–80%
• Vitamin C 500 mg daily × 50 days after wrist fracture: prevents CRPS; level 1 evidence (Zollinger RCT); ~50% risk reduction; prescribe routinely
• Bisphosphonates: IV pamidronate or oral alendronate; evidence for pain reduction in CRPS; most effective in acute/dystrophic phase
• Mirror box therapy: reflection of unaffected limb perceived as affected limb moving; disrupts cortical reorganisation; evidence for benefit in hand CRPS
• Spinal cord stimulation: most effective interventional treatment; RCT evidence (Kemler et al.); after failure of conservative measures; trial stimulation first
• Surgery in CRPS: avoid in active disease; only when remission; aggressive peri-op analgesia and immediate physiotherapy
• Acute phase: warm, red, oedematous; dystrophic: cool, cyanotic, stiff; atrophic: pale, cold, contractures, severe osteoporosis