Complex regional pain syndrome (CRPS), also known as Sudeck atrophy, is a condition which can affect the extremities in a wide clinical spectrum. CRPS is principally a clinical diagnosis - no one imaging study is sensitive or specific to rule in or rule out the syndrome.
Two types of CRPS have been described 8:
- type 1: no underlying single nerve lesion (formerly known as reflex sympathetic dystrophy)
- type 2: underlying nerve lesion identified (formerly known as causalgia)
Patients present after an initiating event (see causes below) with symptoms such as edema, changes in skin blood flow, abnormal motor activity, allodynia or hyperalgesia. Symptoms are often out of proportion to the initiating event and not limited to a single peripheral nerve 8.
- trauma: often minor
- idiopathic: immobilization
- unknown in many cases
- CNS disorders
- myocardial infarction
Occurs in hands and feet distal to the injury.
- severe patchy osteopenia, particularly in the periarticular region
- soft tissue swelling, with eventual soft tissue atrophy
- subperiosteal bone resorption
- preservation of joint space
It is important to differentiate this from disuse osteopenia, since the clinician could initiate aggressive physical therapy for the latter.
- patchy bone marrow edema signal (particularly subcortical), although bone marrow signal may be normal in some cases
- soft tissue edema and enhancement
- skin thickening
- joint effusion
- synovial hypertrophy
- muscle atrophy in later stages
- increased uptake on all three phases
- diffusely increased juxta-articular activity around all joints of a hand or foot on delayed images is the most sensitive indicator
Treatment and prognosis
In most cases, a multidisciplinary approach is required whereby a combination of various treatments may be employed, such as physical therapy, systemic or regional medications, sympathectomy or spinal cord stimulation, and psychotherapy. Interventional radiology can offer pain relief by peripheral nerve block procedures.
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