Skeletal Muscle MRI in Complex Regional Pain Syndrome

Abstract

Conventional magnetic resonance imaging (MRI) sequences of patients with complex regional pain syndrome (CRPS) have shown abnormal signals in skin, soft tissue, joints, bone, and bone marrow, but not yet in skeletal muscles, during the acute phase. The aim of this study was to clarify whether or not the affected muscles in CRPS patients show abnormal MRI signal intensities or signal enhancement by gadolinium dimeglumine during the acute phase. MRI studies of skeletal muscles were performed on three patients of CRPS. Out of three patients, MRI was performed on three at stage 1, one in improving phase, two in remission phase, and one at stage 3. MRI was performed in the transaxial plane with both T2-weighted imaging (T2WI) and fat-suppressed T1-weighted imaging (T1WI) with or without gadolinium dimeglumine enhancement. All patients at stage 1 showed hyperintense muscle signals on T2WI and gadolinium dimeglumine enhancement on T1WI. Following clinical improvement, the hyperintense lesions reverted to near normal. Muscles in the chronic phase showed high signals on both T2WI and T1WI without gadolinium dimeglumine enhancement. MRI abnormalities in the acute phase are consistent with muscular edema, interstitial edema, and vascular hyperpermeability. These MRI findings suggest the presence of hemodynamic abnormalities caused by microangiopathy, sympathetic abnormalities, or both, which may lead to ischemia of affected muscles. Chronic phase abnormalities indicated the presence of muscle atrophy and fibrosis or fatty infiltration of the affected muscle.