Complex Regional Pain Syndrome

The records after an index accident may give clues as to when CRPS started, or whether it was present at all. The symptoms (what the patient states in their  history of complaints) of CRPS are variable, and lie on a spectrum of severity in different patients.

The pain is normally described in ‘neuropathic’ terms, including burning, stabbing, electrical and pins and needles. The patient may also experience swelling, changes in sweating, and skin temperature, either hot or cold. The skin can undergo colour changes such as bluish mottling or redness. Other changes include skin texture, nails and hair growth, spasms, tremors and dystonia.

The diagnosis of CRPS is clinical, and no laboratory or radiological test can definitively exclude or diagnose the condition. This relies on the symptoms described above, and on establishing corresponding signs (what the medical professional finds on examination). The original diagnostic criteria for CRPS adopted by the International Association for the Study of Pain (IASP) in 1994 have now been superseded in both clinical practice and research by the ‘Budapest Criteria’, which were created in 2003. These new criteria are more specific (that is to say, they yield less overdiagnosis). The stricter ‘rules’ reflect in themselves the diagnostic problems of CRPS encountered in the past. The implication here is that CRPS is too often diagnosed when not present.

Physical therapy and increased mobility / movements in the affected limb as early as possible are regarded as vital treatments if CRPS is diagnosed. This would
involve early referral to hand physiotherapy for example, and compliance with exercise is emphasised. Education regarding the disease and early referral to pain management is important.

Many treatment modalities are used for CRPS, and their efficacies can be considered medium / low in general, although some patients do respond to certain treatments with good results. Anti-neuropathic medications are employed, such as pregabalin, amitriptyline and duloxetine.  Topical agents such as lidocaine patches and Capsaicin 8% have also been used. Other options include bisphosphonates, calcitonin, ketamine, and Botox; but these also have low / moderate evidence of efficacy in CRPS. In terms of pain interventions, day case injections called ‘sympathectomies’ can be performed both for upper or lower limbs. These can be followed on by radiofrequency treatments if the former are successful (electrical induced lesioning / modulating of the nerves perpetuating pain). The responses are not guaranteed, but if successful, can assist in rehabilitation. Patient selection is important for success, and is guided by variables such as pain severity and psychological factors.

Spinal cord stimulators (SCS) are electrodes implanted around the spinal cord or nerves, stimulating these structures to produce pain control. They feature in the NICE guidelines as a recommended treatment for CRPS.

Prognosis

Cowell et al (Ref 3) observe that from an orthopaedic perspective (Ref 3), transient CRPS has been reported as a relatively common occurrence early after wrist fractures (up to a third of cases). CRPS can occur within a few months of any limb injury or surgery, but the article points to overdiagnosis if diagnostic criteria were not followed.

It further states that about 80% of patients with CRPS will improve significantly within the first year after trauma, and about a third of patients consider themselves fully recovered at six years. However, up to 20% of patients will have persistent symptoms, and never fully recover. There are also descriptions of CRPS spreading to other limbs, and the course being one of remission and relapse over time. In the medicolegal context, the evolving situation of the disease can influence outcomes: the patient can improve or deteriorate over a period of time before settlement.