Definition and epidemiology
Complex regional pain syndrome (CRPS) is a chronic regional pain disorder in which pain is disproportionate in magnitude and duration to the inciting event, accompanied by sensory, vasomotor, sudomotor/oedema and motor/trophic disturbances. It is subdivided into CRPS type I (no identifiable nerve lesion, formerly reflex sympathetic dystrophy) and type II (associated with a defined nerve injury, formerly causalgia). The Budapest criteria are the validated clinical standard, improving specificity over the older IASP definition.
In children CRPS is predominantly type I, with a striking female and lower-limb predominance and a typical onset in late childhood/adolescence. A preceding trauma — often minor, sometimes a sprain or fracture with immobilisation — is common but not universal. Pediatric CRPS generally carries a better prognosis than adult disease but is frequently diagnosed late after extensive negative investigation.
Clinical features
The cardinal feature is continuing pain disproportionate to any inciting event, often burning, with allodynia (pain to light touch) and hyperalgesia. The affected limb shows autonomic and trophic changes: temperature and colour asymmetry, swelling, altered sweating, and over time changes in hair, nail and skin growth, plus reduced range of motion, weakness, tremor or dystonia. Children may hold the limb rigid, refuse weight-bearing, and develop marked functional disability and school absence. Psychological distress is common and bidirectional — assess it without implying the pain is “not real.”
Diagnosis
CRPS is a clinical diagnosis of exclusion; there is no confirmatory test. The Budapest clinical criteria require all of:
- Continuing pain disproportionate to any inciting event.
- At least one symptom (by patient report) in three of four categories: sensory (hyperaesthesia/allodynia); vasomotor (temperature or skin-colour asymmetry/change); sudomotor/oedema (oedema, sweating change/asymmetry); motor/trophic (decreased range of motion, weakness/tremor/dystonia, or trophic changes).
- At least one sign (on examination) in two or more of those categories.
- No other diagnosis better explains the findings.
(The stricter research version requires a symptom in all four categories.) Investigations — radiographs, MRI, bone scintigraphy, nerve conduction — serve to exclude mimics (occult fracture, infection, tumour, inflammatory arthritis, nerve entrapment), not to confirm CRPS.
See the full criteria: Complex Regional Pain Syndrome (CRPS)
Red flags
- Fever, systemic illness, or raised inflammatory markers — exclude infection/inflammatory arthritis
- Night pain, weight loss, or a palpable mass — exclude malignancy
- Focal neurological deficit beyond the affected region
- Progressive deformity or a rapidly worsening, fixed dystonia
- Diagnostic uncertainty — reconsider the exclusion criterion before committing to CRPS
Management overview
Pediatric CRPS is best managed by an early, multidisciplinary, function-first programme rather than by drugs alone. The cornerstone is intensive physical and occupational therapy — graded mobilisation, desensitisation and restoration of function — supported by psychological therapy (cognitive-behavioural therapy, pain coping, and family work). Pharmacotherapy is adjunctive and aimed at enabling rehabilitation; drug classes used in selected cases include neuropathic-pain agents (gabapentinoids, certain antidepressants), simple analgesics, and topical agents, with bisphosphonates and short steroid courses considered in specific situations by specialists. Opioids have a limited role. Interventional procedures (sympathetic blocks) are reserved for refractory disease in specialist hands. Early diagnosis and prompt restoration of movement give the best outcomes; prolonged immobilisation worsens the syndrome. Refer to a pediatric pain or rheumatology service early.
References
- Harden RN, et al. Validation of the Budapest Criteria. Pain. 2010;150:268–274.
- Harden RN, et al. CRPS Diagnostic and Treatment Guidelines, 5th ed. Pain Med. 2022;23(S1):S1–S53.
- Weissmann R, Uziel Y. Pediatric CRPS: a review. Pediatr Rheumatol. 2016;14:29.
Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.