Reduction of abnormal blood flow in frozen shoulder after shoulder manipulation under ultrasound-guided cervical nerve root block: semiquantitative analysis using dynamic magnetic resonance imaging

Background: We previously reported a characteristic dynamic magnetic resonance imaging (MRI) change in patients with frozen shoulder (FS) and named this abnormal blood flow pattern the “burning sign”. In this study, a semiquantitative method was used to evaluate changes in this abnormal blood flow pattern on dynamic MRI after shoulder manipulation under ultrasound-guided cervical nerve root block (MUC) in patients with FS. Methods: Nineteen patients with FS underwent MUC, with dynamic MRI performed before and after. We used dynamic MRI to semiquantitatively assess changes in the burning sign at the axillary pouch (AP) and rotator interval (RI) by examining the enhancement rate in the signal intensity and the enhancement velocity. Functional assessments included a numeric rating scale score, the range of shoulder motion, the American Shoulder and Elbow Surgeons score, and the Constant score. Results: The burning sign in the AP and RI was observed with dynamic MRI in all patients before MUC. The average interval from MUC until dynamic MRI was 8.2 months (range, 6-12). Clinical results for all patients improved after MUC. The before and after MUC enhancement rates (%) were 217 ± 51 and 85 ± 36 in the AP and 233 ± 61 and 73 ± 40 in the RI, respectively (both P