Complex Regional Pain Syndrome (CRPS) - A Medicolegal Perspective

1. Complex Regional Pain Syndrome (CRPS) -A Medicolegal Perspective Dr. Jon Valentine Consultant in Pain Medicine

2. What is CRPS? • Rare (uncommon) neurological condition most typically affecting the distal aspect of the arm or leg.

3. What is CRPS? • Characterised by features including: • Severe pain. • Hypersensitivity. • Swelling. • Discoloration. • Temperature change. • Abnormal sweating.

4. Terms used for CRPS: • Complex regional pain syndrome types I and II • Reflex sympathetic dystrophy (RSD). • Sudeck’satophy. • Algodystrophy. • Causalgia. • Chronic regional pain syndrome – Incorrect term for CRPS. • CRPS is one type of “chronic pain syndrome”.

5. What CRPS is not: • A ‘diagnosis’ for medically unexplained chronic pain affecting a limb after an injury. • A diagnosis wholly based on the claimant’s testimony and subjective clinical signs.

6. What triggers the onset of CRPS? • Trauma. • Crush injuries. • Soft tissue injuries, sprains & strains. • Fractures. • Cervical spine and shoulder injuries. • Surgery. • Immobilisationin a cast. • Peripheral nerve injuries. • Medical use of needles. • Chemical & electrical injuries. • Unknown / idiopathic.

7. CRPS – Risk / predisposing factors? • None firmly established – definitely nothing that predicts the onset of CRPS – except perhaps previous CRPS. • Psychological factors – nothing definite – stressful life events? • Autoimmune links – Autoimmunity against the β2-adrenergic receptor and muscarinic-2 receptor – (PAIN 2011). • HLA B62 & HLA DQ8 (CRPS with fixed dystonia – PAIN 2009). • Links to asthma and migraine – proposed neurogenic inflammation. Mast cell mediated neural-immune connections?? • Smoking??

8. IASP diagnostic criteria for CRPS Type I (1994): • The presence of an initiating noxious event or cause of immobilisation – optional (!). • Continuing pain, allodynia or hyperalgesia with which the pain is disproportionate to any inciting event. • Evidence at sometime of oedema, changes in skin blood flow or abnormal sudomotor activity in the region of pain. • The diagnosis is excluded by the existence of conditions that would otherwise account for the degree of pain and dysfunction. • CRPS Type II – follows a named nerve injury.

9. Criticism of IASP criteria • Criteria based on consensus of a panel of experts in 1994. • Not clinically validated. • Utilisation of these criteria in the medical literature has been ‘sporadic at best’. • Considered to be adequately sensitive, but with poor specificity leading to over diagnosis of CRPS. • Important medicolegal consequences (USA).

10. CRPS – diagnosisInternational consensus group Budapest 2003: • A “closed” workshop (by invitation only) was held in Budapest in the fall of 2003. Revised clinical and research diagnostic criteria for CRPS were proposed (Pain Medicine – 2007): • Continuing pain that is disproportionate to any inciting event • Patient must report at least one symptom in 3 of the 4 categories: • Sensory: Reports of hyperaesthesia and / or allodynia. • Vasomotor: Reports of temperature asymmetry and / or skin colour changes and / or skin colour asymmetry. • Sudomotor / oedema: Reports of oedema and / or sweating changes and / or sweating asymmetry. • Motor / trophic: Reports of decreased range of motion and / or motor dysfunction (weakness, tremor, dystonia and / or trophic change (hair, nail, skin).

11. CRPS – diagnosisInternational consensus group Budapest 2003: • Must display at least one sign at time of evaluation in 2 or more of the 4 categories (N.B. research criteria = 3 or more): • Sensory: Evidence of of hyperaesthesia (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. • Sudomotor / oedema: Evidence of oedema and / or sweating changes and / or sweating asymmetry. • Motor / trophic: Evidence of decreased range of motion and / or motor dysfunction (weakness, tremor, dystonia and / or trophic change (hair, nail, skin). • There is no other diagnosis that better explains the signs and symptoms.

12. CRPS – diagnosisInternational consensus group Budapest 2003: • “IASP criteria” show high diagnostic sensitivity (1.00), but poor specificity (0.41). • Budapest “clinical criteria” retain the exceptional sensitivity of the IASP criteria (0.99), but greatly improve on the specificity (0.68). • The Budapest “research criteria” result in the highest specificity (0.79). [Validation of proposed diagnostic criteria (the "Budapest Criteria") for Complex Regional Pain Syndrome - PAIN 2010]

13. Fulfilled diagnostic criteria for CRPS?

14. Early features of CRPS: • Disproportionately severe pain in the extremity (initially limited to site of injury). • Movement is painful so there is a tendency for immobilisation. • Localized swelling of the extremity. • Skin changes in extremity (red warm sweaty / blue cold dry). • Mild forms probably not uncommon in Orthopaedic clinics.

15. Medium term features of CRPS: • Persistent pain and hypersensitivity becomes more severe & more diffuse: • Allodynia • Hyperaesthesia • Hyperalgesia / hyperpathia • Swelling spreads away from the site of injury & changes to hard oedema. • Soft tissue and muscle atrophy.

16. Medium term features of CRPS: • Hair becomes coarse & nails grow faster. • Abnormal sweating. • Extremity becomes cold. • Neglect of affected limb. • Patchy bone thinning on x-ray (osteopaenia).

17. Late features of CRPS: • Pain remains constant (can diminish). • Swelling changes to peri-articular thickening. • Skin becomes atrophic, smooth, glossy, tight with scanty hair. Nails become brittle with slow growth. • Stiff joints & muscle atrophy. • Neuromuscular features - spasms, dystonia, tremors, involuntary movements and paresis. • Osteoporosis becomes established.

18. Patterns of spread of CRPS: • Contiguous spread (commonest): Enlargement of initial area from distal to proximal. • Independent spread (IS): To a non-contiguous distant site (6.4%). • Bilateral or mirror image spread: Symmetrical, less (patchy) signs & symptoms on opposite side. • Generalized CRPS [Small % of patients]: affecting the entire body • MalekiJ et al - Patterns of spread in complex regional pain syndrome, type I. Pain 2000 Dec 1;88(3):259-66.

19. Impact of CRPS and other chronic pain syndromes

20. Disability & impact on life: • Poor sleep – pain & hypersensitivity. • Reduced mobility / problems with stairs – need for crutches / wheelchair. • Reduced ability to stand / sit. • Impact on upper limb function – limb neglect & disuse. • Impact on ability to drive & travel etc. • Impact on ability to work / perform domestic duties. • Impact on close relationships / changing role – partner to carer etc.. • Social withdrawal / impact on leisure activities & holidays. • Impact on concentration - medications / severe pain.

21. The psychosocial factors: • Recognised to be important predictors of presentation with chronic pain and pain-related disability. Can be pre-existing, accident and litigation related, or unrelated to the accident and litigation. • Psychological factors include: • Individual beliefs about pain. • Catastrophisation. • Somatisation. • Fear avoidance. • Low mood and depression. • Anxiety. • PTSD. • Stresses – Domestic, litigation, work.

22. Investigation of CRPS

23. Investigations in CRPS • Can assist in securing a diagnosis of CRPS, but: • Negative results do not exclude the diagnosis. • Unlikely to influence clinical management.

24. Plain radiography (x-ray): • Mid to late stages of CRPS • Patchy osteopaenia / osteoporosis (thinning of the bones). • Spotty & localised bone demineralisation. • Established osteoporosis.

25. Infrared thermography:

26. Three-phase isotope bone scan: • Markedly increased blood flow to the right hand compared to the left. • Blood pool images (Image B) and delayed images (Image C) show increased uptake of tracer throughout the right arm. • Can exclude other causes during the sub-acute period (up to 1 year).

27. Future investigations in CRPS?? Functional MRI (f-MRI) The MR signal of blood is slightly different depending on the level of oxygenation. These differential signals can be detected using an appropriate MR pulse sequence as blood-oxygen-level-dependent (BOLD) contrast.

28. Clinical Management of CRPS:

29. Early medical management: • Primary goal is restoration of function: • Pain relief – variable efficacy - pain has both nociceptive & neuropathic features: • Amitriptyline (antidepressant). • Gabapentin / Pregabalin (anticonvulsants). • Ketamine (anaesthetic agent). • Opioids (Morphine / Fentanyl / Oxycodone / Buprenorphine). • Pamidronate (bisphosphonate infusion). • Physiotherapy, mirror-box therapy & home exercises. • Avoid surgery. • Vitamin C ???

30. Side effects of medication: • Analgesic drug-related side effects are common: • Tiredness / fatigue. • Dizziness. • Memory / concentration disturbance. • Bowel disturbance. • Sexual dysfunction. • Weight gain (Antidepressants/Gabapentin/Pregabalin). • Ankle swelling. • Possible significant impact – ability to work / drive etc..

31. Local Anaesthetic Sympathetic Blocks: • Without a good evidence base. • Theoretically appropriate if performed earlyfor sympathetic component of CRPS. • Clear progress needs to be evident to justify repeat procedures. • Estimated cost in private sector - approximately £2000. • Unlikely to be appropriate by the time of pain management medicolegal assessment.

32. Permanent Sympathetic Blocks: • Performed with neurolytics drugs (e.g. Phenol) or radiofrequency lesioning (RF). • Without an good evidence base. • Possibly appropriate in limb viability issues i.e. viability severely threatened by cold & ischaemia. • Estimated cost in private sector- £2000 - £2500.

33. Spinal cord stimulation: • CRPS a recognised indication for SCS on the NHS (NICE). Increasingly used in UK. • High initial cost (£20-25k) • High maintenance cost (£20k+ / 10 yrs): • Need for (multiple) revision procedures. • Replacement impulse generators. • Variable functional improvement, but can be very successful. • Long-term efficacy???

34. What is SCS? The use of an implanted epidural lead electrode to stimulate the spinal cord.

35. Pain Management Programmes: • Aim to optimise physical function and the self-management of chronic pain. • Entirely appropriate for genuine, well motivated patients / claimants who are ready to change. Cost £7k to £12k+. • Unresolved secondary gains (litigation) can have a negative impact on outcome. Best left until after the‘stresses of litigation’ have been removed??? • In many claimants, good evidence of the measured‘improvement’ difficult to identify. • Bath Centre for Pain Services – Young person’s PMP & dedicated CRPS PMP.

36. Surgery? • Surgery might need to be considered if there is an underlying or co-existing Orthopaedic problem, but typically makes CRPS worse. • Surgery can be performed (if essential), but specialist Pain Management / senior Anaesthetist involvement is very important. • Amputation is not recommended in CRPS unless the limb is becoming non-viable, which is rare. • Chronic pain after amputation of CRPS affected limbs is a problem: • Recurrence of CRPS in stump. • Stump pain problems. • Phantom pains.

37. Prognosis • Variable and individual. • Severe CRPS very likely to be permanent. • Less severe forms with minimal objective physical signs can improve significantly with the passage of time, treatment, reduction in psychosocial stressors and motivation.

38. Chronic Pain and CRPS in the medicolegal context

39. Time zero - The accident

40. Time zero + 60 minutes

41. !

42. Medicolegal issues • Causation. • Diagnosis. • Objectivity. • Chronic pain syndrome. • Exaggeration.

43. Causation • Any form of trauma or cause of immobilisation. • STI / bony injury etc. to limb – trauma. • Neck /shoulder injury – cause of immobilisation. • Surgery: • Clinical negligence issues can arise. • Need good reason for operating if CRPS is present. • Standard of care important – specialist Pain Management / Anaesthetic involvement.

44. The importance of diagnosis: • Clinical medicine: • Patients want a diagnosis. Doctors like to provide one. • Diagnosis of CRPS can influence treatment pathway. • Diagnosis of ‘chronic pain syndrome’ is close to irrelevant (in Pain Medicine). • Medicolegal practice: • The diagnosis (especially of of an organic condition) strengthens the claim and assists the Court in understanding the problem. • Monetary value is attached to the diagnosis of CRPS / chronic pain syndrome.

45. Features of CRPS at time of medicolegal assessment: • Severe diffuse pain (deep / burning). • Hypersensitivity (with protection of limb). • Excessive sweating. • Temperature changes (cold). • Tissue swelling (oedema). OBJECTIVE FEATURES • Discolouration - red / blue /purple often ‘blotchy. • Nails growth changes. • Hair growth – abnormal. • Localised muscle spasm / tremor / dystonia etc. • Muscle wasting. OBJECTIVE FEATURES

46. Features of a ‘chronic pain syndrome’ at time of medicolegal assessment: • Disproportionately severe pain. • High levels of pain-related distress. • Disproportionately high disability. • Pain behaviour / apparent overemphasis of pain, sufferance, and disability. • Inappropriate / non-organic clinical signs. • No objective clinical features.

47. Chronic pain, not CRPS • Most claimants reporting chronic pain in an extremity do NOT have CRPS. • The absence of objective clinical signs including the features of CRPS does not exclude medically and ‘medicolegally’ significant chronic pain. • Pain is subjective in nature. Commonly no objective clinical signs. Psychosocial factors are very important (Biopsychosocial model).

48. Chronic pain, not CRPS • In many instances, there is no diagnostic label to adequately describe the claimant’s presentation. • It is often appropriate to describe the claimant as suffering from‘chronic (xx) pain’ (i.e. provide no formal diagnosis). • The term ‘chronic pain syndrome’ is often used in a medicolegal context– provides a diagnosis.

49. Chronic Pain Syndrome • Has no formal definition and provides more of a label for a clinical presentation rather than a true medical “diagnosis”. • There are no established diagnostic criteria. There are no clinical tests to confirm or refute the proposed diagnosis. • Validity is dependent on the reliability of the claimant’s testimony and the genuineness of their presentation at the time of medical assessment. • The term is most often used to provide a ‘diagnosis’ for patients (commonly claimants) reporting chronic pain and disability that is grossly disproportionate to the objective findings of physical examination and clinical investigations.

50. Chronic Pain Syndrome • The International Classification of Diseases. • Chronic pain syndrome - ICD-10-CM Diagnosis Code G89.4 • G89.4 is a specific ICD-10-CM diagnosis code that can be used to specify a diagnosis. • Applicable to: “Chronic pain associated with significant psychosocial dysfunction”. ICD-9-CM will be replaced by ICD-10-CM beginning 1st October 2013, therefore, G89.4 and all other ICD-10-CM diagnosis codes should only be used for training or planning purposes until then.