The challenges of diagnosing Complex Regional Pain Syndrome (CRPS)
Dr Ivan Ramos-Galvez LMS, FRCA, FFPMRCA is a Consultant in Pain Medicine and leading expert witness with a speciality in CRPS. In the second of his series of articles he discusses the challenges CRPS can present in both diagnosing and proving a medico legal claim.
Complex regional pain syndrome (CRPS) usually presents as chronic pain, which can be extremely debilitating, in a single limb. In addition, the affected limb may show differences in skin appearance and temperature, swelling and sweating. Although the condition nearly always follows on from trauma, such as injury or minor surgery, there is no correlation between the severity of the trauma and the level of symptoms experienced, and the amount of pain a patient reports can be totally disproportionate to the original injury. An important feature of the syndrome is allodynia, where even the slightest stimulation can cause significant pain.
A diagnosis of CRPS is primarily one of exclusion of other causes and is usually made by using the new IASP, or Budapest, Criteria. In order to receive a diagnosis, the patient must have:
- Continuing pain which is disproportionate to any inciting event;
- At least one sign (objective; can be seen by another person, in this case a doctor) in two or more of the categories below;
- At least one symptom (subjective; as reported by the patient) in three or more of the categories;
- No other diagnosis that can explain the signs and symptoms.
The categories are sensory, vasomotor, sudomotor/oedema and motor/trophic. The condition is further split, into Types I and II, depending on the absence or presence, respectively, of obvious nerve damage. Patients who do not fit the criteria may still receive a diagnosis of a pain-related condition and this is sometimes classified as Type III CRPS, or CRPS – not otherwise specified (NOS). Patients who used to fit the Budapest Criteria but who no longer do so may also be referred to as CRPS – NOS. One major criticism of these criteria is that they rely heavily on patient-reported symptoms and it is not always clear whether a diagnosis based on them will stand up to scrutiny in a court.
As the condition progresses, symptoms in the limb itself often improve but this is not necessarily true for the level of pain. Patients may experience flare-ups in pain, particularly during physiotherapy treatment, although these normally subside relatively quickly. In addition, the pain may be worse at certain times of day. CRPS is almost always unilateral, and although the pain may spread to another limb as the condition progresses, this is rare and occurs in fewer than 10% of cases. However, transient pain in additional limbs is thought to be much more common. These temporal changes complicate litigation, as it may be several years before the patient’s condition stabilises and the amount of residual pain and/or disability can be properly assessed. Alternatively, legal proceedings may take place when the patient is experiencing a relatively low level of pain, and may not take account of the fact that recurrence is likely.
Clearly, in any situation where there is the possibility of significant financial gain, some patients may be tempted to exaggerate existing symptoms, or fabricate them completely. It can be very difficult for health professionals to accurately identify such patients and very distressing for a genuine sufferer to be labelled as a malingerer. In situations like these, doctors need to take a complete medical history which should be carefully checked for inconsistencies, and make a particularly thorough clinical examination. It may also be helpful to use a measure, such as the Pain Catastrophizing Scale, to assess the validity of the symptoms reported where malingering is suspected.
Presently, there is no cure for CRPS, and although around 80% of patients do see an improvement in their symptoms, many sufferers report significant pain and disability for years after the triggering event. There is some evidence that early diagnosis and treatment greatly increase the chance of a positive outcome for the patient and may even bring about a complete recovery. However, diagnosis is delayed in many patients, due either to a lack of awareness of the condition in the medical profession, or the similarity of the symptoms to numerous other pain-related conditions, which need to be ruled out.
CRPS most closely resembles fibromyalgia and regional pain syndrome and these three conditions are sometimes viewed as a different manifestation of the same underlying process. The essential characteristic of fibromyalgia is pain, but unlike in CRPS where the pain is regional, it usually occurs in numerous areas of the body. Other typical features include sleep disturbance, fatigue, headache, abdominal pain, cognitive dysfunction and depression. Regional pain syndrome usually presents next to or near the spine and is characterised by pain and allodynia, often accompanied by muscular tightness and abnormal skin sensations. It includes conditions such as whiplash and repetitive strain injury. In each of these conditions, there is often increased sensitivity to stimuli such as light and noise, implying that the changes which trigger the conditions are not limited to pain-related neural mechanisms.
CRPS is a syndrome, not a disease, and the signs and symptoms associated with it cover a fairly broad spectrum, which will vary from case to case. Although current guidelines are helpful, in the absence of specific laboratory procedures that conclusively identify the condition, the diagnosis of CRPS will remain controversial.
Dr Ivan Ramos-Galvez is a well-established pain expert, specialising in the diagnosis and treatment of complex pain conditions. He is well regarded as an expert witness in cases involving CRPS, fibromyalgia and other pain conditions.
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Goebel A, Barker C, Turner-Stokes L, et al. Complex regional pain syndrome in adults: UK guidelines for diagnosis, referral and management in primary and secondary care. London: RCP; 2018.
Littlejohn GO, Guymer E. Chronic pain syndromes: overlapping phenotypes with common mechanisms. F1000Research. 2019;8.
Link to first article in the series: An introduction to CRPS