Complex regional pain syndrome (CRPS) is a debilitating condition, characterised by pain in a limb, in association with sensory, vasomotor, sudomotor, motor and dystrophic changes. It commonly arises after an injury to that limb. Pain is typically the leading symptom of CRPS but is often associated with limb dysfunction and psychological distress. Patients frequently report neglect-like symptoms or a feeling that the limb is ‘alien’.
CRPS can be divided into two types based on the absence (type 1, much more common) or presence (type 2) of a lesion to a major nerve. The subtype of CRPS has no consequences for the general approach to management, but the cause of nerve damage in CRPS 2 should always be clarified – urgently in acute cases.
Complex regional pain syndrome (CRPS) is a debilitating, painful condition in a limb associated with sensory, motor, autonomic, skin and bone abnormalities. Pain is typically the leading symptom but is often associated with limb dysfunction and psychological distress. Prompt diagnosis and early treatment are required to avoid secondary physical problems related to disuse of the affected limb and the psychological consequences of living with undiagnosed chronic pain.
Historically, among the many names that CRPS has been called, RSD and causalgia are the best known and still are commonly used. The existence of this confusing taxonomy for CRPS stems, in part, from the many nonstandardized, idiosyncratic, diagnostic schemes used throughout the past century and a half . In 1851, Claude Bernard (1813–1878) was the first to mention a pain syndrome that was linked to sympathetic nervous system dysfunction. Later, a student of Bernard, Silas Weir-Mitchell (1829–1914), employed the term “causalgia” to describe the pain he diagnosed in post-bellum union veterans. (Greek: kausos = heat, algos = pain). Evans first coined the term “reflex sympathetic dystrophy”. Although “RSD” became the most common name to describe this medical condition in the latter 20th century, this name is
Evans first coined the term “reflex sympathetic dystrophy”. Although “RSD” became the most common name to describe this medical condition in the latter 20th century, this name is problematic for several reasons: if a true “reflex” is indeed involved, it is complicated/multisynaptic and not fully characterized; it has since been shown that the assumed “sympathetic”/autonomic changes may not be a constant or causative pain component and furthermore may not be physiologically involved throughout the entire course of the condition in every patient, and actual “dystrophy” is present in perhaps only 15% of cases. The historical lack of agreement regarding standardized nosology and diagnostic criteria for CRPS/RSD has hindered medical and scientific progress in many ways, including lack of comparative studies of treatment of the disorder, and thus has delayed progress in identifying optimal treatments and treatment sequences for its sufferers.
The International Association for the Study of Pain (IASP) has approved the Budapest criteria as the current diagnostic criteria for CRPS. The Budapest criteria now supersede the diagnostic criteria published by the IASP in 1994. It appears that the Budapest criteria are more restrictive than the Orlando criteria.
3. Must display at least one sign* at time of evaluation in two or more of the following categories
4. There is no other diagnosis that better explains the signs and symptoms
To categorise CRPS as ‘mild’, a patient would have few signs of significant pain-related disability or distress, and either conventional or neuropathic drugs would manage pain intensity adequately. Patients who exhibit high levels of pain, disability or distress should be referred to a multidisciplinary pain. Treatment should be initiated as early as possible. If at any stage during treatment the therapist is unsure whether to continue with single-handed therapy or to refer for multidisciplinary rehabilitation, further advice should be sought from an experienced colleague.
If one or more of the following features that indicate moderate or severe disease and/or poor recovery are present, an early referral to a multidisciplinary pain clinic or specialist unit is recommended:
In addition to providing CRPS-specific rehabilitation techniques, specialist units may treat patients with advanced drug and interventional techniques, including spinal cord stimulation. Some regions have direct therapy referral agreements with the local multidisciplinary pain clinic.
Recognition of psychosocial risk factors, referred to as yellow flags can support therapists in understanding contributing causes for suboptimal treatment response. The presence of these factors has been used in other pain conditions to predict chronicity. Yellow flags may be present at initial assessment or may develop and become apparent during treatment. Recognition of these flags may guide referral to multidisciplinary pain clinics and psychology-led PMPs.
Yellow flags include:
(Adapted from Main and Williams 2002)
It is important to consider other possible pathologies (differential diagnoses) during diagnostic assessment:
The four ‘pillars’ of care (education, pain relief, physical rehabilitation and psychological intervention, which address these aims have equal importance. However, full recovery can be difficult to achieve in some, even with early appropriate treatment. Practitioners can support patients by providing a clear diagnosis, information and education about the disease, helping to set realistic goals and, where possible, involving the patient’s partner and/or other family members.
No drugs are licensed to treat CRPS in the UK.
Drugs with efficacy in neuropathic pain should be used according to the National Institute for Health and Clinical Excellence (NICE) guidelines for neuropathic pain and the recommendations of the Neuropathic Pain Special Interest Group of the International Association for the Study of Pain (IASP).
Pamidronate (single 60 mg intravenous dose) should be considered for suitable patients with CRPS less than 6 months in duration as a one-off treatment.
Intravenous regional sympathetic blocks (IVRSB) with guanethidine should not be used routinely in the treatment of CRPS, as four randomised controlled trials have not demonstrated any benefit.
A Dahlem type (think tank) conference was held in Malibu, California, in 1997 to generate consensus as to treatment guidelines for CRPS. All treatments were focused primarily on functional restoration; the use of drugs, blocks, and psychotherapy was reserved for patients failing to progress in the functional algorithm. Interdisciplinary pain management techniques emphasizing functional restoration are thought to be the most effective therapy perhaps by resetting altered central processing and/or normalizing the distal environment.The principle of functional restoration is based on a gradual and steady progression from activation of
The principle of functional restoration is based on a gradual and steady progression from activation of presensorimotor cortices (i.e., motor imagery and visual-tactile discrimination) to very gentle active movements such as progressing from active range of motion (ROM), to weight bearing such as carrying light bags with the upper extremity or putting partial weight on the lower extremity in gait training. This progresses to movements that involve more active load bearing such as the scrub and carry techniques of Carlson. Gradual desensitization to increasing sensory stimulus goes along with increased function. This could include such strategies as progressive stimulation with silk, progressing to other textures of cloth such as towel, or contrast baths that progressively broaden the temperature difference between the two baths. It is thought that perhaps this gradual increase in normalized sensation tends to reset the “altered central processing” in the nervous system. It is important to manage edema in order to optimize ROM and encourage general aerobic activity throughout.
Another basic principle of these functional restoration guidelines is that if patients do not progress through the steps in “a reasonable time,” then other interventions will be progressively added to give the patient greater comfort or confidence so that they may proceed to the next level. For instance, if the allodynic pain is too great, a sympathetic and/or somatic block may give the patient a comfort window of opportunity to begin to entertain more aggressive therapy, or if a patient has kinesiophobia, cognitive behavioral techniques could be undertaken to demonstrate to the patient that movement does not necessarily lead to negative consequences. Blocks, psychotherapy, and drugs should be used mainly in situations of failure to progress; however, if a patient presents with significant concomitant problems (e.g., depression), then certain drugs, blocks, or psychotherapies are recommended from the outset.