Complex regional pain syndrome (CRPS) is a severe disabling chronic pain condition characterised by chronic regional pain with extreme tactile allodynia, plus a combination of other symptoms including vasomotor, sudomotor, and motor changes. The changes are disproportionate to the inciting event. It is a heterogenous disease with inflammatory, autoimmune, sympathetic, and neuropathic features that change over time.
The IASP defines CRPS as a “syndrome characterized by a continuing (spontaneous and/or evoked) regional pain that is seemingly disproportionate in time or degree to the usual course of pain after trauma or other lesion. The pain is regional (not in a specific nerve territory or dermatome) and usually has a distal predominance of abnormal sensory, motor, sudomotor, vasomotor edema, and/or trophic findings. The syndrome shows variable progression over time.”
There are two subtypes of CRPS.
CRPS I (Reflex Sympathetic Dystrophy)
This was previously known as reflex sympathetic dystrophy. There is no precipitating nerve injury. In two thirds of cases the precipitating event is trauma to a distal part of an extremity, particularly fractures, post-surgical states, and sprains. Less common precipitating events are spinal cord injuries, CVAs, head injuries, abdominal disease, and myocardial infarction. Idiopathic cases can occur where it arises following minor trauma that isn't remembered by the patient.
There is asymmetric distal extremity pain and swelling with no demonstrable peripheral nerve injury. Patients often describe spontaneous burning pain in the affected region. The pain is severe and disproportionate to the severity of the inciting event. The pain tends to increase in dependent positions.
As well as spontaneous pain, there is also severe stimulus-evoked pain that often appears early. This includes mechanical and thermal allodynia and/or hyperalgesia. Deep somatic allodynia can occur which is pain with movement and pressure on the joints.
There may be autonomic changes with swelling and alterations in sweating and blood flow to the skin. Acutely the affected region tends to be warmer than the contralateral unaffected region. Sweating abnormalities are almost universal being generally hyperhidrosis, but hypohidrosis can also occur.
Trophic changes include abnormal nail growth, increased or decreased hair growth, fibrosis, thin glossy skin. In chronic stages osteoporosis can occur. Passive joint restriction can occur due to functional motor changes and trophic joint and tendon changes. Weakness is often present, and fine motor skills are particularly impaired. Dystonia occurs in about 10% of cases.
CRPS II (Causalgia)
This was previously known as causalgia. There is a history of injury to a major peripheral nerve. The clinical features are similar to CRPS I. The key difference is that there is evidence of injury to a major peripheral nerve. However the symptoms and signs can (but not always) spread beyond the innervation of the peripheral nerve.
Ott and colleagues published the prevalence of various clinical features of 1043 CRPS patients. An older smaller series of 145 cases was published by Birklein and colleagues. CRPS is found in the arm two thirds of the time and the leg one third of the time. It involves the trunk 0.3% of the time, and is seen in more than one location in 0.7%. 3% are unable to localise the pain
Allodynia (mechanical and/or thermal) and/or Hyperalgesia (punctate)
Pain is the most important sensory symptom!
Spontaneous pain: burning, stabbing/penetrating, dragging. Seen in 75%. The average NRS is 5.12 +/- 2.26. Deep pain in 81%, superficial pain in 31%. Spontaneous dysaesthesia in 38%
Dynamic pain: stabbing/penetrating, burning, dragging, pressuring, throbbing, constricting. The average NRS is NRS 6.34 +/- 2.37. Present on movement in 59%
Augmentation: seen in in 92%. Non painful touch in 58%, physical effort in 55%, orthostasis in 52%, night in 45%, heart in 25%, cold in 31%, agitation in 16%.
Sensory findings are elicited through the Sensory Examination
- Light touch: Hyper-aesthesia in 19%, hypo-aesthesia in 48%, no side to side difference in in 33%.
- Punctate stimulus: Hyper-algesia in 50%, hypo-algesia in 34%, indifferent in 19%.
- Cold stimulus: Increased in 23%, decreased in 23%, indifferent in 55%
- Dynamic mechanical allodynia: in 34%
Temperature asymmetry and/or skin colour changes/asymmetry
There is no correlation between autonomic disturbance and pain.
- Side to side differences in skin temperature
- Warmer CRPS in acute stages and colder CRPS in chronic stages
- Nearly Gaussian distribution around ΔT = .0° (range -8.0 ° to +7.26 °, mean +0.08 ° +/- 1.65 °)
- ≥1°C difference in 48%
- Skin colour variations
- Cyanotic (33%), pallor (9%), or hyperaemic (38%), no difference (26%)
- Pallor and hyperaemic more common in acute CRPS
- Cyanotic more common in chronic CRPS.
- No difference in 26%.
Oedema and/or sweating changes changes/asymmetry
Oedema in 70%. More common in acute CRPS.
Sweating increased in 40%, decreased in 3%, no change in 57%
If call autonomic disturbance as vasomotor (temperature change, skin colour change) and/or sudomotor (sweating, oedema) then 98% have autonomic disturbance.
ROM reduction and/or motor dysfunction and/or trophic change
- Motor symptoms in 97%,
- Difficulty initiating movement in 48%
- Reduced Power
- Reduced active movement in 61%, normal strength in 39%
- Complex strength reduction (handgrip and tip-toe) in 75%
- Reduced ROM in 87%. More pronounced in early stages and in CRPS I, not influenced by oedema
- Reflexes increased in bilateral comparison in 9%, decreased in 19%.
- Tremor in 31% on affected side (can be resting, posture, or mixed)
- Focal myoclonic dystonia in 71%
- Trophic changes of skin, hair, and nails: growth increased in 39%, reduced in 9%, 53% no change.
|Budapest Criteria for Complex Regional Pain Syndrome|
|A-D must apply for a confirmed diagnosis of CRPS||Y/N|
|A||Continuing pain, which is disproportionate to any inciting event|
|B||The patient must report at least one symptom in three of the four following categories:|
|Sensory||Reports of hyperesthesia and/or allodynia|
|Vasomotor||Reports of temperature asymmetry and/or skin colour changes and/or skin colour asymmetry|
|Reports of oedema and/or sweating changes and/or sweating asymmetry|
|Reports of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)|
|C||The clinician must observe at least one sign † at the time of the evaluation in two or more of the following categories:|
|Sensory||Evidence of hyperalgesia (to pinprick) and/or allodynia (to light touch and/or deep somatic pressure and/or joint movement)|
|Vasomotor||Evidence of temperature asymmetry and/or skin colour changes and/or skin colour asymmetry|
|Evidence of oedema and/or sweating changes and/or sweating asymmetry|
|Evidence of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)|
|D||There is no other diagnosis that better explains the signs or symptoms|
|† A sign is counted only if it is observed at time of diagnosis|
|For research diagnostic criteria the patient must report at least one symptom in each of the 4 categories in part B|
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The four pillars of management :
- Patient information and education to support self-management.
- Pain relief (medication and procedures).
- Psychosocial and behavioural management.
- Physical and vocational rehabilitation ( and activities of daily living and societal participation) .
A coordinated Multidisciplinary Program should therefore involve:
- Physiotherapy and OT
- Psychological and Behavioural
- Societal and Vocational
Vocational and litigation support may be provided by specialist rehabilitation teams and, in other cases, these services are integrated into the regional pain management programme
- Active engagement of the patient/family in goal setting, goal review
- the patient remains responsible for their own rate of progress.
- Understanding and insight:
- how emotional stress, muscle tension and de-conditioning can increase pain experience.
- how their own behaviours may serve to exacerbate pain experience.
- self-management approach, including goal setting and pacing.
- the right balance between doing too much and too little.
- relaxation techniques, breathing exercises etc to reverse sympathetic arousal.
- Empowering the family:
- encouraging individual to keep active
Investigation and confirmation of diagnosis:
- Pharmacological intervention (in conjunction with pain team wherever appropriate) to provide a window of pain relief.
- Reassurance that physical and occupational therapy are safe and appropriate.
- Provide medical follow-up to prevent iatrogenic damage through inappropriate referral.
- Support any litigation/compensation claim to its resolution and conclusion.(if desired and appropriate).
- Identify any psychological factors contributing to pain and disability.
- Treat anxiety and depression.
- Identify, explore and proactively address any internal factors (eg counter-productive behaviour patterns)or external influences (eg. perverse incentives, family dynamics etc) which may perpetuate disability/dependency.
- Consider needs of family/carers – provide psychological intervention/counselling where appropriate.
- Provide a practical problem-solving, goal-orientated approach (involving both the patient and their family) to reduce barriers and promote healthy functioning.
Retrain normal body posture.
- Desensitisation – handling the affected part followed by passive stretching/isometric exercise.
- Progression to active isotonic exercise and then strength training.
- General body re-conditioning – cardiovascular fitness.
- Encourage recreational physical exercise and functional goals.
- Techniques to address altered perception and awareness of the limb, eg. mirror visual feedback training or graded motor imagery.
Activities of daily living and societal participation
- Support graded return to independence in activities of daily living with clear functional goals.
- Assessment and provision of appropriate specialist equipment/adaptations to support independence.
- Removal of inappropriate/unnecessary equipment.
- Adaptation of environment.
- Extend social and recreational activities in and outside the home.
- Workplace assessment/vocational re-training.
- ↑ Ott S, Maihöfner C. Signs and Symptoms in 1,043 Patients with Complex Regional Pain Syndrome. J Pain. 2018 Jun;19(6):599-611. doi: 10.1016/j.jpain.2018.01.004. Epub 2018 Feb 2. PMID: 29409933.
- ↑ 145 cases. :Birklein F, Riedl B, Sieweke N, Weber M, Neundörfer B. Neurological findings in complex regional pain syndromes--analysis of 145 cases. Acta Neurol Scand. 2000 Apr;101(4):262-9. doi: 10.1034/j.1600-0404.2000.101004262x./. PMID: 10770524.
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