Complex regional pain syndrome (CRPS): the AU general practice approach

Complex regional pain syndrome (CRPS) is a chronic, persistent regional pain condition characterised by pain that is disproportionate in both intensity and duration to the usual course of any known trauma or lesion. It is accompanied by a characteristic cluster of changes across four domains: sensory (allodynia, hyperalgesia), vasomotor (temperature asymmetry, skin colour change), sudomotor or oedema (swelling, sweating asymmetry), and motor or trophic (weakness, tremor, dystonia, changes to hair, nails, and skin).

Two types are recognised. Type I (~90%) — formerly reflex sympathetic dystrophy (RSD) — develops after fracture, soft-tissue injury, surgery, or immobilisation without identifiable major nerve injury. Type II (~10%) — formerly causalgia — involves a definable nerve injury with pain extending beyond the nerve territory. Both types share the same clinical framework and multidisciplinary management approach.

CRPS incidence is approximately 5–25 per 100,000 person-years; women are affected approximately three times more often than men, with a peak in the perimenopausal period. The most common precipitants in Australian general practice are distal radius (wrist) fractures, ankle fractures, and hand or foot surgery. The International Association for the Study of Pain (IASP) Budapest criteria are the validated diagnostic standard — diagnosis is clinical, not laboratory-based. Early diagnosis and multidisciplinary treatment produce the best outcomes and should be initiated in general practice before waiting for specialist confirmation.

A. Core clinical — the AU general practice framework

Budapest diagnostic criteria (Harden 2010; IASP adopted 2012)

The Budapest criteria — validated by Harden et al. (Pain 2010) — provide a practical clinical framework:

A. Continuing pain disproportionate to any inciting event.

B. Patient reports at least one symptom in three of four categories:

1. Sensory — hyperaesthesia and/or allodynia.
2. Vasomotor — temperature asymmetry, skin colour changes, skin colour asymmetry.
3. Sudomotor/Oedema — oedema, sweating changes, sweating asymmetry.
4. Motor/Trophic — reduced range of motion, motor dysfunction (weakness, tremor, dystonia), trophic changes (hair, nail, skin).

C. At least one sign present on examination in two of four categories (same categories as B).

D. No other diagnosis better explains the signs and symptoms.

Note: the clinical version of the criteria (used in practice) requires symptoms in 3 of 4 categories; the research version uses 2 of 4, which improves specificity at the cost of sensitivity.

History

• Pain character — burning, throbbing, or shooting quality; constant or paroxysmal; out of proportion to the precipitating event; allodynia (pain from light touch, clothing) and hyperalgesia (exaggerated response to pinprick).
• Precipitant — fracture (especially distal radius), surgery, soft-tissue injury, even minor trauma; occasionally no identifiable trigger.
• Symptom timeline — acute “warm” phase (warm, red, swollen limb) versus chronic “cold” phase (cool, mottled, atrophic) — important for both diagnosis and management planning.
• Motor changes — weakness, difficulty using the limb, tremor, or involuntary posturing.
• Skin and nail changes — shiny or atrophic skin, increased or decreased sweating, brittle or ridged nails, altered hair growth.
• Functional impact — capacity for work, self-care, activities of daily living; workers’ compensation status.
• Psychological comorbidities — depression, anxiety, pain catastrophising, PTSD — important not as causes of CRPS but as significant modifiers of outcome.

Examination

• Temperature asymmetry — compare affected vs unaffected limb; >1°C asymmetry is significant (infrared thermometer or back of hand comparison is clinically useful).
• Skin colour — erythema or cyanosis early; mottled or dusky later.
• Oedema — compare limb circumference.
• Allodynia testing — light touch with a soft brush or cotton wool.
• Range of motion — active and passive; compare bilateral.
• Trophic changes — skin texture (shiny, atrophic), nail condition, hair growth.
• Motor findings — weakness, tremor at rest or with intention, fixed dystonic posture in chronic cases.

Investigations

No single test diagnoses CRPS — investigations support clinical assessment and exclude differentials.

• Plain X-ray — patchy demineralisation (Sudeck’s atrophy) after three or more months; excludes non-united fracture, bony lesion.
• MRI — bone marrow oedema (early/acute); soft-tissue changes; excludes infection, avascular necrosis, occult fracture.
• Three-phase bone scan — periarticular uptake pattern supports early CRPS; sensitivity declines with chronicity.
• Nerve conduction studies (NCS) and EMG — important to identify nerve injury (Type II) versus Type I; exclude alternative peripheral neuropathy.
• Bloods — FBC, ESR/CRP, urate, rheumatoid factor, anti-CCP — exclude septic arthritis, gout, inflammatory arthritis.
• Skin temperature measurement (infrared thermometry) — quantify asymmetry; useful for monitoring.

Differential diagnosis

Important differentials include: peripheral nerve injury (nerve conduction studies), cellulitis or septic arthritis (fever, localising signs, bloods), deep vein thrombosis or lymphoedema, inflammatory arthritis (rheumatoid, reactive, psoriatic), undetected non-union fracture, erythromelalgia (episodic burning with erythema, worse with heat), Raynaud’s phenomenon, peripheral neuropathy (polyneuropathy pattern, NCS findings), and rare entities including thalamic pain post-stroke.

B. Multidisciplinary treatment evidence

Physiotherapy and occupational therapy — foundational. Treatment is built around restoration of function and graded normalisation of sensory input. The physiotherapy approach for CRPS is distinctive:

• Graded Motor Imagery (GMI) — a three-stage AU-developed programme from Professor Lorimer Moseley’s group: left/right limb discrimination training, mental imagery of movement without moving the limb, then mirror therapy. The Moseley Lancet 2004 and follow-up randomised controlled trials showed significant reduction in pain and disability versus physiotherapy alone. This addresses cortical reorganisation — the central mechanisms contributing to maintained CRPS.
• Mirror therapy — visual illusion where the unaffected limb’s reflection appears as the affected limb; supports cortical remapping; evidence-based adjunct particularly effective in the earlier stages.
• Desensitisation — graded exposure to different textures and temperatures to progressively reduce allodynia.
• Graded active exercise — progressive tolerated movement starting from what the patient can achieve without inducing severe flare; avoids immobilisation, which worsens CRPS.
• Pain-Exposure Physical Therapy (PEPT) — Dutch protocol that deliberately uses pain-contingent activity (activity despite pain, rather than pain-avoiding); RCT evidence supports it for functional outcomes in motivated patients.
• Compression, lymphatic drainage, hydrotherapy — useful for oedema management and tolerated movement in water.

Psychological — adjunctive but important. Psychology is a core component of multidisciplinary pain management, not an add-on.

• Pain neuroscience education (“Explain Pain” — Moseley) — helping patients understand central sensitisation mechanisms reduces fear, catastrophising, and avoidance behaviours.
• CBT for chronic pain — evidence-based (multiple RCTs and systematic reviews) for improving function, mood, and coping; reduces pain catastrophising.
• ACT (Acceptance and Commitment Therapy) — values-based engagement with life despite persistent pain; growing evidence base.
• Treat depression and anxiety — SSRIs and SNRIs for comorbid mood disorders (some SNRIs also have modest neuropathic pain benefit — duloxetine).

Prevention — vitamin C. Zollinger et al. and multiple subsequent RCTs show that vitamin C supplementation after distal radius or wrist fracture reduces CRPS incidence — NNT approximately 17. This is recommended in Australian and international fracture management guidelines. The supplementation regimen used in trials is detailed in the FAQ above and is widely available over the counter at low cost.

Preventive measure	Evidence	Notes
Vitamin C supplementation post-distal radius / wrist fracture	RCTs (Zollinger; multiple confirmatory) — NNT ~17	AU and international fracture guidelines; OTC; no established role once CRPS present
Early mobilisation post-fracture / surgery	Observational + expert consensus	Avoids disuse-related contribution
Adequate post-operative analgesia	Consensus — undertreated acute pain may predispose	Multimodal preferred

C. Pharmacotherapy and interventional options

Neuropathic pain pharmacotherapy per eTG and AMH:

• Pregabalin / gabapentin — modest evidence in CRPS specifically; widely used as standard neuropathic pain agents. PBS Authority Required for pregabalin — the requirement for documented failure of two first-line agents (or contraindication) can be a barrier. Private prescription is an option.
• TCAs (amitriptyline, nortriptyline 10–75 mg nocte) — PBS general; common first-line adjunct; useful when sleep disturbance accompanies pain.
• SNRIs (duloxetine 30–60 mg daily) — PBS general for major depression; evidence for neuropathic pain (particularly diabetic peripheral neuropathy); used off-label in CRPS with comorbid depression.

Bisphosphonates — most evidence for early CRPS with documented bone marrow oedema on MRI:

• Pamidronate IV — multiple RCTs demonstrating pain reduction and functional improvement in early CRPS; specialist administration in hospital or infusion setting.
• PBS listing for pamidronate is for hypercalcaemia of malignancy and Paget’s disease — use in CRPS is off-label; patient may bear out-of-pocket cost.

Corticosteroids — brief course in acute/early phase (prednisolone 30–40 mg/day for two to three weeks, then taper) when clearly inflammatory features are present; small RCTs support early use. Not appropriate for chronic-phase CRPS.

Ketamine IV infusion — RCTs show short-term pain reduction; delivered in specialist pain medicine clinic settings; psychotomimetic side effects, tolerance, and cost limit use to refractory cases.

Opioids — generally avoided in CRPS. Long-term opioids are associated with worse functional outcomes in chronic pain, and CRPS specifically responds poorly. Opioid-induced hyperalgesia is a risk. Short-term use for perioperative acute pain management is a different situation.

Interventional options (specialist pain medicine):

• Sympathetic nerve blocks (stellate ganglion for upper limb, lumbar sympathetic for lower limb) — modest and variable evidence; appropriate in sympathetically maintained pain; Cochrane review found uncertain benefit overall.
• Spinal cord stimulator (SCS) — Kemler et al. demonstrated long-term benefit in refractory CRPS; MBS item 39134/39135 for device implantation. Selection and trial period with external stimulator precede permanent implantation.
• Dorsal root ganglion stimulation — emerging; ACCURATE RCT showed advantages for lower limb and focal CRPS.
• Intrathecal baclofen — for refractory CRPS with fixed dystonia; specialist neurosurgery referral.

D. Australian operations

Medicare — GP coordination and allied health access:

Item	Use
721	GP Management Plan — chronic CRPS qualifies
723	Team Care Arrangement — enables allied health referrals
10960	Physiotherapy under TCA (5 sessions/year combined)
10958	Occupational therapy under TCA
10968	Psychology under TCA
2715/2717	Mental Health Treatment Plan — 10 psychology sessions/year via Better Access
39134/39135	Spinal cord stimulator implantation

PBS barriers. Pregabalin requires Authority — failure of or contraindication to two first-line neuropathic agents before Authority is granted. If PBS Authority is not immediately achievable, amitriptyline (PBS general) is an appropriate first-line agent. Pamidronate for CRPS is off-label.

Workers’ compensation pathways. CRPS commonly arises from workplace fractures and post-surgical complications — wrist, hand, and ankle injuries are most frequent. State workers’ compensation schemes (WorkCover Victoria, icare NSW, WorkCover Queensland, WorkCover WA, ReturnToWorkSA, WorkSafe ACT, WorkCover Tasmania) fund physiotherapy, occupational therapy, psychology, and specialist care via approved-provider pathways. Documentation requirements are high — Budapest criteria documentation in the clinical record, a clear treatment trial history, and work capacity certification are standard requirements. Insurer-funded multidisciplinary rehabilitation programmes are a common management pathway. Avoid early prognosis statements labelling CRPS “permanent” or “untreatable” — these worsen functional outcomes via expectation effects.

Pain medicine specialist referral. Refer to a pain medicine specialist (Fellow of the Faculty of Pain Medicine, ANZCA — FFPMANZCA) for: complex diagnostic uncertainty, refractory CRPS after initial multidisciplinary trial, consideration of interventional procedures (sympathetic blocks, ketamine infusion, SCS), and major workers’ compensation or medico-legal contexts. Major Australian multidisciplinary pain services include: Royal North Shore Hospital (Sydney), Royal Melbourne Hospital, Royal Brisbane and Women’s Hospital, Royal Adelaide Hospital, Royal Perth Hospital. Telehealth pain specialist consultation reduces access barriers for rural and remote patients.

Painaustralia provides a National Pain Strategy, consumer resources, and a service directory. Faculty of Pain Medicine ANZCA provides clinical statements and pain medicine specialist verification.

E. Special populations

Children and adolescents. Paediatric CRPS has a distinct phenotype — cooler and less red than the adult warm phase; lower-limb (especially knee and ankle) more common than upper limb; often follows minor injury or sporting trauma. Prognosis is generally better than in adults, with aggressive multidisciplinary physiotherapy and psychology providing good outcomes in most. Opioids and invasive interventions are rarely appropriate. Specialist paediatric pain units (Children’s Hospital Westmead, Royal Children’s Hospital Melbourne, Queensland Children’s Hospital) are the appropriate referral for complex cases.

Pregnancy. Limited data exist for CRPS management in pregnancy. Non-pharmacological approaches — physiotherapy, mirror therapy, psychology, graded motor imagery — are prioritised. Avoid pregabalin, gabapentin, most SNRIs, bisphosphonates, and opioids. Paracetamol and carefully considered low-dose TCA under obstetric guidance may be appropriate. Specialist pain medicine and obstetric co-management is recommended for significant CRPS in pregnancy.

Older adults. Polypharmacy, falls risk, and cognitive effects of neuropathic agents (particularly pregabalin and gabapentin in the elderly — significant sedation and falls risk) require careful prescribing. Start low, titrate slowly. Physiotherapy-led rehabilitation and psychology remain the foundation. TCA use in older adults carries anticholinergic burden — nortriptyline is preferred over amitriptyline. Falls assessment and environmental review are standard components of management.

When to escalate

Refer to pain medicine specialist for:

• Diagnostic uncertainty after clinical assessment and initial investigations.
• Refractory CRPS — failure to improve after six to eight weeks of supervised multidisciplinary physiotherapy and psychology.
• Consideration of interventional procedures — sympathetic nerve block, ketamine infusion, SCS trial.
• Complex workers’ compensation or medico-legal context.
• Fixed dystonia or major motor disability unresponsive to physiotherapy.

Refer to emergency for:

• Acute compartment syndrome — a separate emergency mimicking CRPS acutely; severe pain, hard compartment, pallor, paraesthesia, paralysis — requires urgent surgical review.
• Septic arthritis or osteomyelitis presenting with limb pain and fever — requires urgent assessment and intravenous antibiotics.
• Serious suicidality in the context of chronic pain and psychological comorbidity — Lifeline 13 11 14, Beyond Blue 1300 22 4636.

What this article is and is not

This is general health information drawn from Australian pain management and general practice guidelines — eTG, AMH, RACGP persistent pain resources, Australian Pain Society, Faculty of Pain Medicine ANZCA, Painaustralia, and key international trials (Moseley, Harden Budapest criteria, Kemler SCS, Zollinger vitamin C). It is not personal medical advice and does not create a doctor–patient relationship. Decisions about treatment — particularly pharmacotherapy, interventional procedures, and workers’ compensation management — require individual clinical assessment.

For Australian consumer information: HealthDirect — CRPS, Better Health Channel — CRPS, Painaustralia. For crisis support: Lifeline 13 11 14.

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Sources cited

1. Therapeutic Guidelines (eTG) — Pain: CRPS
2. RACGP — Persistent pain management
3. Australian Pain Society (APS)
4. Faculty of Pain Medicine ANZCA
5. Painaustralia — National Pain Strategy
6. Australian Medicines Handbook (AMH)
7. PBS Schedule
8. HealthDirect — CRPS
9. Better Health Channel — CRPS
10. Harden RN et al. Budapest Criteria validation. Pain 2010;150:268
11. Moseley GL. GMI for CRPS. Lancet 2004;364:396
12. Bruehl S. CRPS. BMJ 2015;351:h2730
13. Zollinger PE et al. Vitamin C for CRPS prevention after wrist fracture
14. International Association for the Study of Pain — Budapest criteria
15. Royal College of Physicians UK — CRPS management 2018