The complex regional pain syndromes (CRPS I and CRPS II), also known as reflex sympathetic dystrophy and causalgia, have been recognized for the past 2,500 years. Despite its long history, the diagnosis and treatment of CRPS are still challenging. These syndromes can be characterized by discrete sensory, motor, and autonomic findings, but many patients with CRPS continue to suffer for years without the diagnosis. Although much progress has been made in the understanding of CRPS, many questions still remain unanswered. CRPS is probably a disease of the central nervous system. Yet, peripheral inflammatory processes, abnormal sympathetic- afferent coupling, and adrenoreceptor pathology may also be part of the picture. A close multidisciplinary approach amongst the pain medicine consultants, psychologist, physical and occupational therapists, and neurologist is necessary to achieve the maximum treatment outcomes. If conventional treatment (e.g. pharmacotherapy) fails to show a significant response within 12 weeks, an interventional technique such as spinal cord stimulation (SCS) needs to be tried. The current concepts of CRPS could be replaced by a new mechanism-based term or group of terms in the near future leading to improved clinical guidelines. This article reviews the different aspects of CRPS including its definition, classification, epidemiology and natural history, clinical presentation, pathophysiology and management.
Causalgia ; Central Nervous System ; Classification ; Complex Regional Pain Syndromes ; Consultants ; Diagnosis* ; Epidemiology ; Humans ; Natural History ; Pathology ; Psychology ; Reflex Sympathetic Dystrophy ; Spinal Cord Stimulation

Reflex sympathetic dystrophy (RSD) is a common rheumatic disorder manifesting painful swelling, discoloration, stiffening and atrophy of the skin. Radiographic alterations include small, spotty subperiosteal bone resorption (SBR) and diffuse porosis, and MR imaging shows bone and soft-tissue edema. The purposes of current investigation were to assess 99mTc HDP pinhole SPECT (pSPECT) findings of RSD, to correlate them with those of radiography and MRI and to speculate about causative mechanism of SBR which characterizes RSD. pSPECT was performed in five patients with RSD of the foot. pSPECT showed small, discrete, spotty hot areas in the subperiosteal zones of ankle bones in all five patients. Diffusely increased tracer uptake was seen in the retrocalcaneal surface where the calcaneal tendon inserts in two patients with atrophic RSD. pSPECT and radiographic correlation showed spotty hot areas, that reflect focally activated bone turnover, to closely match with SBR. Further correlation with MRI showed both spotty hot areas and SBR to coincide in location with the insertions of ligaments and tendons, onto which pulling strain is constantly exerted. In contrast, the disuse osteoporosis in unstrained bones did not show any more significantly increased tracer uptake than normal cancellous bones.
Adult ; *Bone Resorption ; Bone and Bones/pathology ; Edema ; Female ; Foot Bones/pathology ; Foot Diseases/pathology ; Human ; Image Processing, Computer-Assisted ; Magnetic Resonance Imaging/*methods ; Male ; Middle Aged ; Osteoporosis/pathology ; Reflex Sympathetic Dystrophy/*pathology ; Technetium/*pharmacology ; Tomography, Emission-Computed, Single-Photon/*methods