Sudeck's disease stage 1, or diabetic Charcot's foot stage 0? Case report and assessment of the diagnostic value of MRI

BACKGROUND The diagnosis of Sudeck's syndrome stage 1 (nowadays termed complex regional pain syndrome I, abbreviated CRPS I) is based on clinical features, namely swelling and pain in a limb. Plain X-ray may be normal. In the absence of pain sensitivity, e.g. in diabetic neuropathy, CRPS I of the foot can be mistaken for Charcot's foot stage 0 (so-called neuro-osteoarthropathy). CASE PRESENTATION The case of a type-1 diabetic woman is reported, in whom CRPS I following a calcaneal fracture was mistaken for Charcot's osteoarthropathy (because of bone marrow edema displayed by conventional MR imaging). In addition, a review is presented on 6 consecutive cases with CRPS I of the foot, and on 20 cases with Charcot's foot stage 0, with particular emphasis on MR imaging findings. The number of bones per foot affected with marrow edema was similar in either condition, with a tendency towards a more patchy, diffuse distribution of bone marrow edema in CRPS I. Bone marrow edema apparently regressed more promptly in response to treatment in Charcot's foot stage 0. CONCLUSION Differentiation of CRPS I from Charcot's foot stage 0 remains a diagnostic dilemma in patients with pain insensitivity. Conventional MRI may be helpful, when repeated for monitoring the treatment response.