Radiology_Aug04 Abstract Complex regional pain syndrome (CPRS), type 1 is a pain disorder that develops unpredictably and can fol- low a minor injury. A 12-year-old boy presented with severe pain in the feet and could not walk or stand weight bearing. Normal X-rays showed osteopenic changes and radiolucent lines, which appeared to be stress frac- tures. Three-phase bone scintigraphy showed no uptake in the left lower leg on the blood pool phase or on the immediate or delayed images. This indicated typical CPRS type 1 in chil- dren. The uptake in the right foot was increased and the stress fracture and other illness could not be differentiat- ed. Computed tomography was done to exclude stress fractures. Only osteopenic changes in both calcaneus bones were found and there was no evidence of cortical stress fractures. Magnetic resonance images revealed oedema in the calcaneus and talus bones of both feet. The patient received epidural narcotic infusion with sympathetic blockage for 1 week combined with extensive physiothera- py. The blood pool phase of the bone scan became normal within 2 weeks, and increased uptake in both feet was noticed. The patient was followed up with MRI every 3 months and the bone marrow oedema disappeared after 6 months. Introduction Reflex sympathetic dystrophy (RSD) or the newer synonym, com- plex regional pain syndrome (CPRS), type 1 is a pain disorder that develops unpredictably and can follow a minor injury.1,2 CRPS type 1 is not limited to a single peripheral nerve distribution, and is associated with oedema, changes in skin blood flow, abnormal sudomotor activity in the region of the pain, and allodynia or hyperalge- sia. In CRPS type 2 or causalgia there is history of a peripheral nerve injury, thus the pain and autonomic distur- bance can be identical to CRPS type 1 but has a nerve-specific distribution.2 Case report A 12-year-old boy presented with severe pain in the feet, worse in the left foot, which increased over a period of 2 weeks to such an extent that he could not walk or stand weight bear- ing. Although he was active in a num- ber of sports no incident of injury was reported. On examination both feet were cold, pale and mildly swollen and he experienced paraesthesiae (pins and needles), hyperalgesia (extreme pain response to a minimally painful stim- ulus) and allodynia (unpleasant painful sensation induced by non- painful stimulus such as light touch on the affected area). Normal X-rays were taken of both feet. These showed marked osteo- penic changes and radiolucent lines which appeared to be stress fractures, especially in the left calcaneus (Figs 1a and 1b and Figs 2a and 2b). Three-phase bone scintigraphy was done, which showed no uptake in the left lower leg on the blood pool CASE REPORTS 38 SA JOURNAL OF RADIOLOGY • August 2004 Reflex sympathetic dystrophy/complex regional pain syndrome, type 1 S H Botha MB ChB, MFamMed Department of Diagnostic Radiology University of the Free State Bloemfontein Fig. 1a. Lateral X-ray of right foot showing radiolu- cent lines and osteopenia. Fig.1b. Lateral X-ray of left foot showing radio- lucent lines and osteopenia. Fig. 2a. Oblique X-rays of right foot showing pos- sible stress fractures of calcaneus bones. phase or on the immediate or delayed images (Fig. 3). This indicated typical RSD in children. In contrast, adult uptake is usually increased. When the intensity was increased, the delayed images in the left calcaneus showed a slight increase in uptake. The uptake in the right foot was increased and the stress fracture and other illness could not be differentiated (Fig. 4). Computed tomography (CT) was done to exclude stress fractures. Only osteopenic changes in both calcaneus bones were found and there was no evidence of cortical stress fractures (Fig. 5). Magnetic resonance images (MRIs) were taken of both feet and revealed marked oedema in the calca- neus and talus bones of both feet. Some soft-tissue oedema especially over the left ankle was also present (Fig. 6 and Figs 7a and 7b). There was contradiction between the two diagnoses of stress fractures and CPRS type 1. As CPRS type 1 is a clinical diagnosis the boy was treated as such. He was admitted into hospital and received epidural narcotic infusion with sympathetic blockage for a period of 1 week combined with extensive physiotherapy (3 times a day). Fortunately he recovered remarkably. If he had had stress fractures his condi- tion would have worsened. The blood pool phase of the bone scan became normal within 2 weeks, and increased uptake in both feet was noticed. He was followed up with MRI every 3 months and the bone marrow oedema disap- peared after 6 months. Discussion The physiology, diagnosis and management of CPRS type 1 is dis- cussed below. 39 SA JOURNAL OF RADIOLOGY • August 2004 CASE REPORTS Fig. 2b. Oblique X-rays of left foot showing possi- ble stress fractures of calcaneus bones. Fig. 3. Blood flow phase showing cut-off sign in the left lower leg. Fig. 4. Blood pool phase showing still no uptake in the left leg with increased uptake in the right foot. Fig. 5. Axial CT image of both feet showing osteopenic changes. Fig. 6. Sagittal STIR image of the left foot showing soft-tissue oedema and bone marrow oedema in calcaneus and talus bones. Fig. 7a. Axial STIR MR images of both feet show- ing oedema of soft tissue and bone marrow. Fig. 7b. Coronal STIR MR images of both feet showing oedema of soft tissue and bone marrow. Pathophysiology In patients with sympathetically maintained pain it is likely that the major site of abnormality is in the wide-dynamic-range neurons in the spinal cord. The hypothesis is that an initiating trauma event sensitises these neurons with associated proliferation of alpha-receptors on low threshold mechanoreceptors and in the sur- rounding tissues. A normal mechanical stimulus results then in excessive firing of wide-dynamic-range neurons, caus- ing abnormal pain sensation. The pro- liferation of alpha-receptors in the sur- rounding tissues, including the blood vessels and other end organs explains the clinical features of autonomic acti- vation seen in the disorder.3 Clinical features Pain is the main clinical manifesta- tion of CRPS type 1 and is dispropor- tionate to that expected of the severity of the underlying injury. The pain combines with autonomic disturbance such as skin colour, skin temperature, sudomotor activity and swelling changes.1,3 Precipitating factors The initiating cause in CRPS type 1 may be either trauma of external origin or iatrogenic, post surgery. In some patients particularly children, no defi- nite injury can be identified.1,4 Diagnosis The diagnosis of CRPS type 1 is essentially clinical and is made on the basis of the combination of excessive pain together with autonomic distur- bance in the area of the pain. Specific investigations Plain X-ray: Routine radiography was first used to confirm the presence of CRPS type 1. However, the soft tis- sue swelling and demineralisation are nonspecific and a late manifestation of the illness.5 Bone scan: Bone scintigraphy pro- vides a non-invasive method of diag- nosis. In adults it demonstrates increased uptake on both blood pool and delayed images, and in children a decreased uptake in all the phases. This is, however, only 60% sensitive.5,6 Magnetic resonance imaging: MRI can provide supportive evidence for CRPS type 1. Soft-tissue changes and bone marrow oedema are early changes and muscle atrophy is present in the disorder’s later stages. MRI may also be helpful in patient follow-up.5 Management The treatment of CRPS type 1 includes physiotherapy, drugs (analge- sia, antidepressants, anticonvulsants) and sympathetic blockade.1,3 Conclusion Although CPRS type 1 is a clinical diagnosis, imaging methods such as bone scintigraphy and MRI are helpful in the differential diagnosis and in fol- low-up of these patients. References 1. Blombery PA. A review of reflex sympathetic dystrophy. Aust Fam Physician 1995; 24: 1651- 1655. 2. Walker SM, Cousins MJ. Complex regional pain syndromes: including ‘reflex sympathetic dystro- phy’ and ‘causalgia’. Anaesth Intensive Care 1997; 25: 113-125. 3. Phelps GR, Wilentz S. Reflex sympathetic dystro- phy. Int J Dermatol 2000; 39: 481-486. 4. Murray CS, Cohen A, Perkins T, Davidson JE, Sills JA. Morbidity in reflex sympathetic dystro- phy. Arch Dis Child 2000; 82: 231-233. 5. Schweitzer ME, Mandel S, Schwartzman RJ, Knobler RL, Tahmoush AJ. Reflex sympathetic dystrophy revisited: MR imaging findings before and after infusion of contrast material. Radiology 1995; 195(1):211-214. 6. Zyluk A, Birkenfeld B. Quantitative evaluation of three-phase bone scintigraphy before and after the treatment of post-traumatic reflex sympa- thetic dystrophy. Nucl Med Commun 1999; 20: 327-333. CASE REPORTS 40 SA JOURNAL OF RADIOLOGY • August 2004