Opinion
Complex regional pain syndrome: a diagnostic challenge for clinicians
2nd Mar 2017
Read the first article in the series here.
Complex Regional Pain Syndrome (CRPS) is a condition that is frequently disputed in personal injury compensation claims. Even for clinicians who regularly see cases of CRPS it can represent diagnostic difficulties. For other clinicians who see cases of CRPS less frequently, it maybe wrongly referred to as Chronic Regional Pain Syndrome or Chronic Pain Syndrome.
Clinical presentation
CRPS is a disorder of the nervous system in which pain is accompanied by disturbances in the motor nervous system and the regulatory nervous system, producing a variable clinical picture characterised by one or more of the following features.
Sensory Nerve disturbances |
Movement Abnormalities |
Regulatory Changes |
Hypersensitivity (increased sensation to a normally painful stimulus eg heat or pin prick) |
Weakness |
Temperature abnormalities |
Allodynia (pain in response to a normally non-painful stimulus eg light touch) |
Stiffness |
Perspiration (pseudo motor) changes |
Hyperpathia (pain in response to a repeated stimulus eg vibration) |
Muscle wasting |
Changes in skin, hair and nail growth |
|
Tremor |
Blood flow changes (pale or mottled skin) |
|
|
Swelling |
The features of CRPS are not constant and may be present only intermittently or only in response to a provoking activity. Temporal changes are also seen following injury as the condition either improves or alters from an acute (inflammatory) phase of CRPS characterised by redness, swelling and warmth, into a chronic phase characterised by muscle atrophy, contracture, coldness and pallor.
While CRPS is usually confined to one of the limbs, it is also (less commonly) seen in non-extremities such as the breast or the knee. CRPS can also spread from one side of the body to the opposite side and may ‘skip’ from an injured or immobilised part of the body to a remote and uninjured part of the body.
Mechanism of CRPS
While the exact mechanism of CRPS in humans is uncertain, research underpinned by functional Magnetic Resonance Imaging (fMRI) suggests that CRPS is the result of nervous system re-wiring in response to injury or immobilisation. An analogy that may be usefully employed to explain this condition to patients is that in CRPS the nervous system is like an old-fashioned hardwired telephone exchange in which many thousands of its cables become wrongly connected to each other.
Treatment and recovery
Recovery from CRPS is highly variable. There are cases reported in which symptoms of CRPS have lasted for only a few days before complete resolution of symptoms, and others where no discernible recovery ever occurs. While it is difficult to assign an individual case of CRPS an accurate prognosis, early interventions aimed at restoring normal use of the affected body part are generally associated with earlier and more complete recovery.
Treatments for Complex Regional Pain Syndrome |
Corticosteroid medication |
Vitamin C |
Antineuropathic pain medications |
Nerve blocks |
Neuromodulation |
Mirror box therapy |
Graded motor imagery |
Because of the wide range of treatments that may be usefully employed, an individual with CRPS is optimally managed within the setting of an inter-disciplinary team of healthcare professionals.
Diagnostic difficulties
Diagnostic difficulties arise because there is no single test or investigation specific for CRPS and diagnosis is reliant upon the presence or absence of various combinations of symptoms and signs. Historically, clinicians have changed their consensus opinion as to what combination of clinical signs and symptoms are necessary to diagnose this condition and whether such clinical signs and symptoms have to be present at the time of examination or can have been recorded as present at any time since the injury or immobilisation occurred.
Expert reports can be requested months or years after symptoms of CRPS are first noticed. This presents additional difficulties, because an individual who initially displayed sufficient signs and symptoms to diagnose CRPS, may, at the time they present for independent medical examination, have begun to recover and no longer display the same signs and symptoms as they did earlier.
AMA Guides to Evaluation of Permanent Impairment 5th Edition criteria to diagnose CRPS |
Budapest Consensus Criteria for the diagnosis of CRPS |
AMA Guides to Evaluation of Permanent Impairment 6th Edition criteria to diagnose CRPS |
< 8 of the above signs present at time of examination = no CRPS; > 8 of the above signs present at time of examination = CRPS probable. |
1. Continuing pain which is disproportionate to any inciting event. 2. Must report at least one symptom in 3 of the 4 following categories
3. Must display at least one sign at the time of examination in 2 or more of the following categories
4. There is no other diagnosis that better explains the signs and symptoms. |
1. Must report at least one symptom in 3 or 4 of the following categories:
2. Must display at least one sign at time of evaluation in 2 or more of the following categories:
3. There is no other diagnosis that better explains the signs and symptoms. |
Table 1 Comparison of the different diagnostic criteria currently used to diagnose CRPS
Chronic Regional Pain Syndrome and Chronic Pain Syndrome
Historically, CRPS has been referred to as Reflex Sympathetic Dystrophy (RSD), Sympathetic Dystrophy or Pseudecks atrophy. Today, CRPS may be mistakenly referred to as ‘Chronic Regional Pain Syndrome’ or ‘Chronic Pain Syndrome’.
While the International Taxonomy of Painful Conditions (an official publication of the International Association for the Study of Pain) does not recognise either ‘Chronic Regional Pain Syndrome’ or ‘Chronic Pain Syndrome’ as official diagnoses, the AMA Guides to Evaluation of Permanent Impairment, 5th ed, refers to ‘Chronic Pain Syndrome’ as a ‘term frequently used to described a painful condition with substantial psychological overlay’. ‘Chronic Pain Syndrome’ is essentially a fall-back position masquerading as a diagnosis which appears more acceptable than stating that the clinician is unable to find or explain a cause for pain.
Considerations for independent medical examinations
Several points need to be considered when pursuing a claim resulting in CRPS. The most important is to instruct an appropriately qualified and experienced expert who regularly treats this condition. Secondly, consider alternate diagnoses that may be similar to and share treatments with CRPS yet may have less stringent diagnostic criteria such as neuropathic pain conditions. Thirdly, instruct your expert to consider the presence of CRPS symptoms and signs at any time following injury rather than relying upon the occasion of examination to arrive at their diagnosis.
Dr Marc Walden is a registered pain medicine physician, specialist anaesthetist, independent medical examiner and the principal of Greenslopes Medicolegal.
This is the second article in a series of three. His next article will discuss psychological pain syndromes.
The views and opinions expressed in these articles are the authors' and do not necessarily represent the views and opinions of the Australian Lawyers Alliance (ALA).
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