Etiopathophysiology

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Budapest diagnostic criteria for CRPS: https://doi.org/10.1016/j.pain.2010.04.030

Continuing pain, which is disproportionate to any inciting event
Must report at least one symptom in three (clinical diagnostic criteria) or four (research diagnostic criteria) of the following categories:
- Sensory: hyperesthesia or allodynia
- Vasomotor: temperature asymmetry, skin colour changes, or skin colour asymmetry
- Sudomotor or oedema: oedema, sweating changes, or sweating asymmetry
- Motor or trophic: decreased range of motion, motor dysfunction (weakness, tremor, or dystonia), or trophic changes (hair, nails, or skin)
Must display at least one sign at time of diagnosis in two or more of the following categories:
- Sensory: hyperalgesia (to pinprick) or allodynia (to light touch, deep somatic pressure, or joint movement)
- Vasomotor: temperature asymmetry, skin colour changes or asymmetry
- Sudomotor or oedema: oedema, sweating changes, or sweating asymmetry
- Motor or trophic: decreased range of motion, or motor dysfunction (weakness, tremor, or dystonia), or trophic changes (hair, nails, or skin)
No other diagnosis better explains the signs and symptoms </aside>

![(A) Acute CRPS with hyperaemia, swelling, and glossy skin. (B) Chronic, cold-type CRPS with blue discoloration of the fingers, glossy skin, and increased hair and nail growth. (C) CRPS-related dystonia of the left ankle and foot with plantar flexion and inversion of the ankle, and flexion of the toes; oedema and increased hair growth are also visible. CRPS=complex regional pain syndrome.

Marinus J, Moseley GL, Birklein F, et al. Clinical features and pathophysiology of complex regional pain syndrome. The Lancet Neurology. 2011;10(7):637-648. doi:https://doi.org/10.1016/s1474-4422(11)70106-5](attachment:ee7eb1f5-5c4d-41e2-95b8-46c6b8bc0089:gr1_lrg_(1).jpg)

(A) Acute CRPS with hyperaemia, swelling, and glossy skin. (B) Chronic, cold-type CRPS with blue discoloration of the fingers, glossy skin, and increased hair and nail growth. (C) CRPS-related dystonia of the left ankle and foot with plantar flexion and inversion of the ankle, and flexion of the toes; oedema and increased hair growth are also visible. CRPS=complex regional pain syndrome.

Radiology

Radiographic findings: Courtesy of Dr Nabarun Das, MD

Inhomogenous (juxtaarticular) rarefaction of the bone with prominent trabeculations around the region of trauma

HO of wrist pain following trauma: Focal area of medullary lucencies in the wrist joint involving the carpals and the distal radioulnar bones without any cortical breach or dilocations. Diffusely atherosclerotic vessels notes, secondary to possible renal osteodytrophy.
Case courtesy, Dr Nabarun Das, MD
#SMCHCase

Spotty areas of rarefaction with trabeculations noted in a non-homogeneous pattern involving the carpels, metacarpels & phalanges and distal parts of visualized radioulna. This patient also had a history of fall one week back.
Case courtesy, Dr Nabarun Das, MD
#SMCHCase

Management

Proposed algorithm for the management of complex regional pain syndrome: https://doi.org/10.1016/S1474-4422(24)00076-0

![Adapted from recommendations in the UK Royal College of Physicians guidelines.64 First-line treatments are usually administered in non-specialist settings and, in most cases, irrespective of symptom duration. First-line treatments should be done together and have equal importance. Second-line treatments might be delivered individually or together within a multidisciplinary pain management programme. Referral to a multidisciplinary programme is usually appropriate after no response to 6 months of treatment but might be fast-tracked as determined by specialists with specific CRPS experience. The patient's partner or family should be involved in the treatment planning process when possible. CRPS=complex regional pain syndrome. NSAID=non-steroidal anti-inflammatory drug. TCA=tricyclic antidepressant. SNRI=serotonin–noradrenaline reuptake inhibitor. *For people with excessive fear that activity will cause pain, movement should be progressed using load or time contingencies within tolerance. † A single intravenous infusion of 60 mg pamidronate (or equivalent) could be given as a one-off treatment for CRPS of less than 4 months in duration, considering evidence available since publication of the RCP guideline. ‡Delivered by specialist physiotherapists or occupational therapists if possible. §Titrated to therapeutic levels. Where pain reduction is insufficient or tolerance develops, drug reduction or cessation is advised. ¶Only considered when symptoms are refractory and the patient has received intensive integrated multidisciplinary management. Preimplantation screening should entail a thorough psychosocial evaluation, and patients should be informed of risks and advised that benefit is likely to decline over time. Rarely appropriate for patients with symptom duration less than 18–24 months.

Ferraro MC, O’Connell NE, Sommer C, et al. Complex regional pain syndrome: advances in epidemiology, pathophysiology, diagnosis, and treatment. The Lancet Neurology. 2024;23(5):522-533. doi:https://doi.org/10.1016/s1474-4422(24)00076-0](attachment:fa7b7613-1e1e-4997-9656-f001a896d862:gr2.jpg)

Adapted from recommendations in the UK Royal College of Physicians guidelines.64 First-line treatments are usually administered in non-specialist settings and, in most cases, irrespective of symptom duration. First-line treatments should be done together and have equal importance. Second-line treatments might be delivered individually or together within a multidisciplinary pain management programme. Referral to a multidisciplinary programme is usually appropriate after no response to 6 months of treatment but might be fast-tracked as determined by specialists with specific CRPS experience. The patient's partner or family should be involved in the treatment planning process when possible. CRPS=complex regional pain syndrome. NSAID=non-steroidal anti-inflammatory drug. TCA=tricyclic antidepressant. SNRI=serotonin–noradrenaline reuptake inhibitor. *For people with excessive fear that activity will cause pain, movement should be progressed using load or time contingencies within tolerance. † A single intravenous infusion of 60 mg pamidronate (or equivalent) could be given as a one-off treatment for CRPS of less than 4 months in duration, considering evidence available since publication of the RCP guideline. ‡Delivered by specialist physiotherapists or occupational therapists if possible. §Titrated to therapeutic levels. Where pain reduction is insufficient or tolerance develops, drug reduction or cessation is advised. ¶Only considered when symptoms are refractory and the patient has received intensive integrated multidisciplinary management. Preimplantation screening should entail a thorough psychosocial evaluation, and patients should be informed of risks and advised that benefit is likely to decline over time. Rarely appropriate for patients with symptom duration less than 18–24 months.