Definitions

Complex regional pain syndrome is a clinical entity—without a pathognomonic diagnostic test or marker—defined by regional pain, autonomic dysfunction, vasomotor changes or instability, atrophy (trophic), and functional impairment.

Synonyms for this syndrome include reflex sympathetic dystrophy, causalgia, and algodystrophy. CRPS type I includes pain, functional impairment, autonomic dysfunction, and dystrophic changes in the absence of an identifiable peripheral nerve lesion, injury, or irritation (traditionally reflex sympathetic dystrophy); CRPS type II is identical in the presence of an identifiable nerve lesion (traditionally causalgia).^1,2 CRPS type III expands the concept to include all extremity pain dysfunction and is not discussed (Table 24-1). CRPS type I or II may be sympathetically maintained (SMP) or sympathetically independent (SIP) based on relief or persistence of pain after sympatholytic intervention.^3,4 The SMP type may become SIP over time; this distinction recognizes the dynamic nature of dystrophic responses. In general, the SMP type has a better prognosis and different treatment approach.

TABLE 24-1 Classification of Complex Regional Pain Syndrome

Reproduced with permission from Koman LA, ed: Bowman Gray Orthopaedic Manual. Winston-Salem, NC: Orthopaedic Press, 2007.

Incidence and Prognosis

Fracture of the distal radius and ulna is one of the most common injuries producing CRPS.^5–10 Tight casts,⁸ the presence of a nociceptive event such as compression of the median nerve, injury of the median or ulnar nerves, overdistraction, instability of the distal radioulnar joint (DRUJ), or ulnar fracture may contribute to CRPS after fractures of the distal radius.^11,12

In prospective studies, CRPS type I or II is reported in 26% to 39% of patients,^5,8,10,13 whereas, in retrospective studies, incidences of less than 2% are reported.^14–20 This variation may be partly explained by the difference in study design, patient inclusion/exclusion criteria, and strictness of definition. CRPS after fracture of the distal radius is not linked statistically to patient age, sex, number of attempted fracture reductions, adequacy of reduction,⁵ side affected, or time from fracture to reduction and immobilization.¹³ Atkins and associates⁵ found no relationship to the severity of the fracture, whereas Bickerstaff and Kanis found CRPS was more likely to occur in patients who have sustained severe fractures.¹³

The importance of early recognition and management of CRPS cannot be overemphasized; this is the single most important predictor of functional recovery and pain relief.^9,21 However, delay in diagnosis of 6 to 26 weeks is common.²² In general, for patients diagnosed within 1 year of onset, the overall prognosis is favorable in 80% of cases, whereas there is significant morbidity in 50% of patients for whom treatment is delayed for more than 1 year.²³ Unfortunately, the prognosis of CRPS occurring after fracture of the distal radius varies from other entities and good outcomes are less common, with stiffness at 12 weeks correlating with residual CRPS at 10 years.²⁴

Diagnosis and Evaluation

There is significant variation in the presentation of CRPS. The classic dystrophic progression from the acute phase (<3 months) to the dystrophic phase (3 to 6 months) to the chronic phase (>6 months) occurs infrequently; therefore, staging CRPS by the number of months is often inappropriate.²³ In this chapter we discuss the use of objective instruments and tests that serve to stage CRPS physiologically and functionally.

Symptoms and Signs

Pain

CRPS does not exist in the absence of pain; however, different patients may have variable perceptions of pain, including allodynia, hyperalgesia, hyperesthesia or hypoesthesia, and hyperpathia. Pain descriptions also vary (“burning,” “throbbing,” “pressing,” “cutting,” “searing,” “shooting,” or “aching”). If present, nociceptive foci, including peripheral nerve lesions and mechanical derangements, must be identified. The nociceptive trigger may not be identified until the SMP is managed and the dystrophic manifestations are treated. An objective and reproducible analysis of pain symptoms is accomplished by the use of standardized and/or validated instruments,²⁵ including the visual analog scale (VAS),^26,27 the pain portion of the Rand Corporation Short Form 36 (SF-36),²⁸ the McGill Short Form Pain Questionnaire,²⁹ and/or self-administered questionnaires designed to assess upper extremity symptoms/function.^30,31 Cold intolerance, or pain on exposure to cold, may be analyzed by using the McCabe Cold Sensitivity Severity Scale.³²

Trophic Changes

Upper extremity signs of CRPS include muscle and joint stiffness, edema, osteopenia, atrophy of the hair and nails, hypertrophy of skin, difficulty in fine finger manipulation, fixed posturing, and arthrofibrosis (Fig. 24-2). In 30% of cases, skin, hair, and/or nail changes may be apparent within 10 days of onset.³³ Osteopenia is common and involves both cortical and cancellous bone (Fig. 24-3).⁶

FIGURE 24-2 Hand of a CRPS patient with autonomic dysfunction and trophic changes. Note the metacarpophalangeal joints are extended or slightly flexed as are the proximal interphalangeal joints.

Rights were not granted to include this figure in electronic media. Please refer to the printed book.

(From Koman LA, ed: Bowman Gray Orthopaedic Manual. Winston-Salem, NC: Orthopaedic Press, 1996.)

FIGURE 24-3 Plain radiograph showing diffuse osteopenia in a patient with CRPS after fracture of the distal radius and ulna (fracture line visible). Also note the juxtacortical demineralization, subchondral erosions, and cysts.

Rights were not granted to include this figure in electronic media. Please refer to the printed book.

(From Koman LA, ed: Bowman Gray Orthopaedic Manual. Winston-Salem, NC: Orthopaedic Press, 1996.)

Autonomic Dysfunction

Eighty percent of CRPS patients report a medical history of symptoms of autonomic dysfunction.³⁴ Affected extremities may either be “hot” or “cold.” Sweating abnormalities (excessive or anhidrosis), vasomotor changes (redness or bluish discoloration of the extremity), and temperature (heat or cold) sensitivity/intolerance are the most common manifestations of autonomic dysfunction. During the painful stages of CRPS, autonomic dysfunction may be reported in up to 98% of patients.^25,35,36

Diagnostic Testing

Evaluation of Pain

Although algometers,³⁷ dolorimeters,³⁸ computer-assisted stimuli,³⁹ or thermal pain thresholds may be used to quantify pain,⁴⁰ mechanical testing using Von Frey or Semmes-Weinstein monofilaments provides objective assessment of the quantity of pain and is a practical office procedure.²³

Plain Radiographs

In approximately 80% of patients, regional osteopenia is evident on plain radiographs.^5,38 These changes are visible only if there is significant demineralization, which may not be apparent until after a long period from onset of symptoms.⁴¹ The features of classic Sudeck’s atrophy include diffuse osteopenia with juxtacortical demineralization and subchondral erosions or cysts (see Fig. 24-3).²³

Bone Scintigraphy

Three-phase technetium-99m bone scintigraphy (TPBS) (Fig. 24-4) has a significant role in the diagnosis of CRPS.^36,42–45 The diagnostic accuracy of phase III of TPBS may equal that of the three-phase scan.⁴³ TPBS has a high specificity but poor sensitivity.^29,36,42,46 It provides objective support for the clinical diagnosis of CRPS, in combination with the other tests, but has no prognostic significance²⁵ or any value in determining the appropriate management approach.^21,36,47,48 The classic positive TPBS demonstrates increased periarticular uptake throughout the distal extremity.

FIGURE 24-4 Abnormal (phase III) bone scan demonstrating increased periarticular uptake. Increased metaphyseal-epiphyseal uptake in the radius is secondary to a fracture.

(Reproduced from Koman LA, ed: Wake Forest University School of Medicine Orthopaedic Manual. Winston-Salem, NC: Orthopaedic Press, 2001, with permission.)

Evaluation of Autonomic Control

Total digital blood flow equals the sum of the thermoregulatory flow (normally, 80% to 95%), and nutritional flow (normally, 5% to 20%).²³ In CRPS, inappropriate control of arteriovenous shunting leads to ischemia and deprivation of nutritional flow,^25,35,49,50 which is the common denominator in either a “warm, swollen” hand with high total flow or a “cold, stiff” hand with low total flow (Fig. 24-5). These components may be assessed by measurements of the digital temperatures, laser Doppler fluxmetry (LDF), vital capillaroscopy, laser Doppler perfusion imaging (LDPI), and isolated cold stress testing (ICST).^{25,36,49,51–58} These measurements provide objective reproducible data, measure the effect of intervention, and guide treatment.^25,59–61 Sweat function may be evaluated quantitatively, and combined with the measurements of ICST, provides objective evidence of autonomic function.^9,25,62 Relief after sympatholytic intervention defines SMP.^3,4 SMP may be diagnosed by nerve blocks of the stellate ganglion (most common), epidural space, brachial plexus, or peripheral nerves using short-acting or intermediate-acting local anesthetics.⁹ Stellate blocks are effective in only 70% to 75% of cases²; therefore, it is essential to confirm the sympatholysis by obtaining indirect evidence (i.e., Horner’s syndrome, nasal congestion, and/or facial anhidrosis) or by direct evidence (i.e., increase in temperature (3°C), venous engorgement of the hand veins, dry skin, changes in skin color, and characteristic laser Doppler changes).^2,29,63 Thermography provides a large quantity of data and allows comparison with the contralateral extremity⁶⁴; repeated measurements associated with stress over time are reproducible and correlate with symptoms.⁶⁵ However, higher temperatures measured by thermography do not correlate with skin surface flow in CRPS.⁵⁰ The use of a physiological stressor increases the predictive and diagnostic value of thermography.^29,66

FIGURE 24-5 The common underlying mechanism of CRPS is deprivation of nutritional flow and resulting pain via abnormal arteriovenous (AV) control through arteriovenous anastomoses (AVA). This is true in either a warm, swollen hand with increased total flow or a cold, stiff hand with decreased total flow.

Rights were not granted to include this figure in electronic media. Please refer to the printed book.

(From Koman LA, ed: Bowman Gray Orthopaedic Manual. Winston-Salem, NC: Orthopaedic Press, 1996.)

Management