Complex Regional Pain Syndrome
Complex regional pain syndrome (CRPS) is a chronic pain condition where pain after an injury becomes severe, long‑lasting, and out of proportion to what would normally be expected, often affecting a hand, arm, foot, or leg. CRPS involves changes in sensation, movement, circulation, and the immune and nervous systems, so early recognition and multidisciplinary treatment are important for preserving function and improving quality of life.[1][2][3]
WHAT IS COMPLEX REGIONAL PAIN SYNDROME?
CRPS usually develops after a fracture, sprain, surgery, or other trauma, but the injury itself is often relatively minor compared with the intensity and duration of symptoms.
The pain is regional (involving part or all of a limb), not limited to a single nerve or joint, and is typically burning, deep, or throbbing, with marked sensitivity to touch and movement.[2][3][1]
Two main types are recognised:
CRPS I: No confirmed major nerve injury (previously “reflex sympathetic dystrophy”).[3]
CRPS II: A clear nerve injury is present (previously “causalgia”).[3]Both types share similar clinical features and are managed in similar ways.[1][3]
KEY SYMPTOMS AND SIGNS
The diagnosis of CRPS is clinical and based on the Budapest Criteria, which require ongoing pain plus a combination of sensory, autonomic, and motor changes in the affected area.[2][1]
Common features include:
Sensory changes: Severe pain disproportionate to the injury, allodynia (pain from light touch or clothing), and hyperalgesia (exaggerated response to painful stimuli).[1][2]
Autonomic and vasomotor changes: Temperature differences between limbs, colour changes (red, purple, pale), swelling, abnormal sweating, and shiny or thin skin.[4][2][1]
Motor and trophic changes: Stiffness, tremor, weakness, reduced range of motion, and changes in hair, nails, or bone density.[5][2][1]
Symptoms often fluctuate and can spread beyond the original injury site. In some people, pain and sensitivity become more widespread, suggesting central sensitisation.[6]
WHAT CAUSES CRPS? CURRENT UNDERSTANDING
CRPS is now considered a multifactorial neuro‑immune disorder involving peripheral nerves, the spinal cord, brain, and autonomic and immune systems.[4][1]
Key mechanisms include:
Peripheral and central sensitisation: Injured or inflamed nerves release neuropeptides (substance P, CGRP) and glutamate, which increase excitability in the spinal cord and brain, leading to ongoing pain amplification.[7][6]
Autonomic dysfunction: Abnormal coupling between sympathetic nerves and pain fibres causes changes in blood flow, temperature, sweating, and colour, as well as “sympathetically maintained pain.”[2][1]
Neuroinflammation and immune involvement: Increased inflammatory cytokines (IL‑1β, IL‑6, TNF‑α) and autoantibodies have been found in affected tissues and blood, suggesting both autoinflammatory and autoimmune contributions.[4][1]
Cortical reorganisation and body perception changes: Brain imaging shows altered representation of the affected limb in the cortex, associated with disturbed body perception and neglect‑like symptoms in some patients.[6][1]
Psychological distress does not cause CRPS, but mood, anxiety, trauma history, and pain catastrophising can influence severity, coping, and recovery.[3][1]
HOW IS CRPS DIAGNOSED?
There is no single blood test or scan for CRPS; diagnosis is based on clinical features and exclusion of other causes.[1][2]
The Budapest Criteria require:
Continuing pain disproportionate to any inciting event.
At least one symptom in three of four categories (sensory, vasomotor, sudomotor/oedema, motor/trophic).
At least one sign in two or more categories on examination.
No better diagnosis to explain the presentation.[2][1]
Bone scans, X‑rays, or MRI may show supportive findings such as patchy bone density changes or oedema, but these are not specific and are mainly used to rule out other conditions (e.g. infection, fracture, deep vein thrombosis).[8][1]
WHY EARLY TREATMENT MATTERS
Outcomes in CRPS are variable: some people improve substantially, especially with early intervention, while others develop chronic, disabling pain and stiffness.
Observational data suggest that earlier diagnosis, active mobilisation, and multidisciplinary management are associated with better pain control, limb function, and return to daily activities.[9][3][1][2]
TREATMENT: A MULTIDISCIPLINARY APPROACH
Because CRPS involves sensory, motor, autonomic, and psychological processes, guidelines recommend an integrated, multidisciplinary approach rather than relying on any single medication or procedure.[5][9][1]
PHYSICAL AND OCCUPATIONAL THERAPY
Movement is central to CRPS treatment, even when it is uncomfortable.
Early, gentle mobilisation with physiotherapy and occupational therapy helps maintain range of motion, prevent contractures, and reduce swelling.[8][5][1]
Techniques include desensitisation (graded exposure to touch), oedema management, functional use of the limb, hydrotherapy, and graded strengthening or gait training.[5][1]
Graded motor imagery and mirror therapy use visual and mental exercises to retrain cortical representation of the limb and reduce pain, with several trials showing benefit in CRPS.[9][8][1]
Regular practice is important; the aim is to stay within tolerable limits while slowly expanding what the limb can do.
MEDICATIONS
Medications target different components of CRPS and are usually used as part of a broader plan.
Anti‑inflammatory and immune‑modulating agents: Short courses of oral corticosteroids (e.g. prednisone) may reduce swelling and pain in early CRPS. Bisphosphonates and calcitonin have shown pain relief and functional gains in some trials, particularly in early disease.[8][5][3][1]
Neuropathic pain medicines: Gabapentinoids (gabapentin, pregabalin) and certain antidepressants (e.g. SNRIs or tricyclics) help some patients by dampening nerve hyperexcitability and improving sleep and mood.[3][1]
Topical and infusion therapies: Lidocaine patches, compounded off-label topical creams/ointments, and intravenous ketamine infusions may reduce severe pain in selected cases, though ketamine requires specialist supervision and monitoring.[9][1][3]
Analgesics and opioids: Simple analgesics and, in some cases, carefully managed opioids can be used for severe pain, but long‑term opioids alone rarely normalise function and must be weighed against tolerance and side‑effects.[5][3]
No single drug works for everyone; treatment is often a process of cautious trial, monitoring, and adjustment.
PSYCHOLOGICAL SUPPORT
Living with CRPS can be frightening and overwhelming. Psychological support does not imply the pain is “in your head”; rather, it helps manage the emotional and cognitive load of a complex physical condition.
Cognitive‑behavioural therapy (CBT) and related approaches address catastrophising, fear of movement, sleep problems, and mood, which are known to influence pain and disability in CRPS.[1][5]
Trauma‑informed care is important if CRPS follows a distressing accident or surgery, or if there is pre‑existing PTSD or developmental trauma.[4][1]
Psychological input is most effective when integrated with physical and medical
treatment.
INTERVENTIONAL AND NEUROMODULATION PROCEDURES
For some people, interventional pain procedures can provide important additional relief when conservative measures are insufficient.
Sympathetic nerve blocks (e.g. stellate ganglion block for upper limb CRPS, lumbar sympathetic block for lower limb) can reduce sympathetically maintained pain and reverse vasomotor changes in a subset of patients, sometimes enabling more active physiotherapy.[8][2]
Spinal cord stimulation (SCS): Randomised trials suggest that SCS combined with comprehensive pain management can provide clinically meaningful pain relief and improved quality of life for carefully selected patients with chronic CRPS, particularly when conservative treatments have failed. Benefit may diminish over years, and device implantation carries risks, but for some it remains a valuable option.[3][1]
Other neuromodulation approaches (e.g. dorsal root ganglion stimulation) are emerging and may offer targeted benefit, though long‑term data are still developing.[9][1]
Interventional options are usually considered after detailed specialist assessment, with clear goals and an understanding that responses are variable and often partial.
PROGNOSIS AND LIVING WELL WITH CRPS
Long‑term outcome varies: some people experience substantial improvement or remission, while others have persistent symptoms but can still achieve better function and quality of life with appropriate support.[2][3]
Factors associated with better outcomes include:
Early diagnosis and early, active rehabilitation.[9][1]
Strong engagement in physiotherapy and self‑management strategies.
Addressing mood, sleep, and stress, and maintaining social and work roles as much as possible.[5][1]
Even when CRPS becomes chronic, targeted treatments, pacing, and psychological strategies can reduce pain intensity and interference, helping people reconnect with valued activities and roles.[8][5]
KEY MESSAGES FOR PATIENTS AND FAMILIES
CRPS is a real, biologically complex condition involving pain, nerves, blood flow, and the immune system—not a sign of weakness or exaggeration.[4][1]
Early recognition and multidisciplinary care—combining physical and occupational therapy, medications, psychological support, and, when appropriate, interventional procedures—offer the best chance of improvement.[1][5][9]
Recovery is often gradual and non‑linear, but with persistence, specialist support, and a tailored plan, many people with CRPS can reduce pain, regain function, and rebuild a meaningful life.[5][8]
