Complex regional pain syndrome underdiagnosed: CRPS type 1 is an under-recognized problem in limbs recovering from fracture or immobilized post-stroke

Journal of Family Practice, June, 2005 by Anna Quisel, James M. Gill, Peter Witherell

Practice recommendations

* Complex regional pain syndrome (CRPS) type 1 may be diagnosed by history and physical exam with no further testing (B). Several different diagnostic criteria have undergone validity testing: the 1993 IASP criteria, Bruehl's criteria, and Veldman's criteria; there is no compelling reason to recommend 1 set of criteria over the others (C).

* Some cases of CRPS type 1 may be preventable. Some cases of CRPS type 1 in post-stroke upper extremity hemiplegia (also known as shoulder-hand syndrome) may be prevented by early inpatient rehabilitation (C) and avoidance of shoulder trauma to the affected arm (B). Some cases of post-fracture CRPS type 1 may be prevented with 500 mg vitamin C daily started upon diagnosis of fracture and continued through healing (B).

Do you have a patient recovering from a limb fracture who is complaining of pain and tenderness long after most patients with a similar injury would be symptom free? The problem may be an under-recognized one--complex regional pain syndrome (CRPS) type 1, also known as reflex sympathetic dystrophy. The problem is also encountered in immobilized limbs of post-stroke patients.

Persons with persistent post-traumatic pain eventually diagnosed with CRPS type 1 often undergo unnecessary testing resulting in inappropriate or delayed treatment. (1)

Signs and symptoms typical of CRPS type 1 can also occur transiently with a normally recovering immobilized limb, (2,3) so diagnosis of CRPS type 1 is based on increasing severity and duration of signs and symptoms (level of evidence [LOE]: 3; consensus guidelines) (4):

* pain

* hyperalgesia/allodynia (pain or exaggerated response resulting from a normally painless or only slightly painful stimulus)

* joint stiffness

* swelling

* autonomic abnormalities (often sweating and temperature differences compared with the unaffected limb).

* Diagnosis: Watch recovery course over first 9 weeks

Clinicians face a number of challenges in diagnosing CRPS type 1. No psychological or personality traits appear to predispose to CRPS type 1 (LOE: 2, lower-quality literature review). (5) Fracture types and severity of injury among persons who develop CRPS type 1 are not significantly different from persons who recover normally (LOE: 2, case control studies). (6,7) The key is to remain alert to deviation from the normal course of recovery.

Studies have shown that 9 weeks post-injury, persons with persistent pain, tenderness, swelling, joint stiffness (fingers and wrist), and sweating or temperature changes in the injured limb may have CRPS type 1 (LOE: 2, case series and case control studies). (6,8) In a prospective case series (n=109), no new cases of CRPS type 1 developed beyond 9 weeks (LOE: 2, case series). (8)

Diagnostic criteria: No consensus

No one test identifies all persons with CRPS type 1. There is no objective gold standard for diagnosis. (9) Instead, researchers and clinicians must rely on clinically derived diagnostic criteria. Unfortunately, despite the development of diagnostic criteria by the IASP in 1994 (TABLE 1), (4) experts have not reached consensus on the best method of diagnosis, and several different sets of diagnostic criteria are used. (7,10)

Initial IASP criteria. Of these, the 1994 IASP consensus-based diagnostic criteria appear to be most widely used in the literature. These criteria were intended as a starting point, requiring validation through future clinical research. (4,11) In further studies using controls with neuropathic conditions, IASP criteria have demonstrated low specificity (TABLE 2). (11,12)

Criteria refinements. Derived from 1 of these studies, Bruehl's criteria were subsequently developed to improve the IASP criteria (TABLE 1). (11) Several other sets of diagnostic criteria exist, but only Veldman's criteria (TABLE 1), (13) which have been adopted as the standard in the Netherlands, have undergone further study. (14) Studies of Bruehl's and IASP criteria have measured specificity and sensitivity, and along with Veldman's criteria, interobserver reliability (TABLE 2). (11,12,14,15) However, these numbers must be interpreted with care due to the absence of an objective and independent gold standard.

The absence of an objective gold standard does not mean CRPS type 1 is not a "real" disorder. (12) In developing diagnostic criteria for CRPS, the IASP turned to models developed for other conditions without objectively measurable findings: the International Headache Society (IHS) classification and the Diagnostic and Statistical Manual of Mental Disorders (DSM). These descriptive systems are based largely on history and self-reported symptoms rather than on clinical signs and laboratory tests. The accuracy of these types of diagnostic criteria is refined over time, through repeated, controlled validation studies using the best means available. (11)

Specificity of criteria. Specificity has been tested using controls with neuropathic conditions. (11,12) In these studies, nonblinded clinicians applied CRPS type 1 diagnostic criteria, except the exclusion criterion, to patients who had either CRPS type 1 or neuropathic pain from other causes. Many persons with peripheral neuropathy met criteria for CRPS type 1. However, as stated in the IASP criteria, the diagnosis of CRPS type 1 is not considered until common causes of neuropathic pain and post-traumatic limb pain have been excluded. (4) As long as the primary care provider considers and rules out other causes of pain, the clinically relevant specificity of these criteria is likely much higher.