Ultrasound-guided short- and long-axis injection (Figure 1)
An independent physician with 7 years of experience performed ultrasound-guided injections with a 10–18-MHz liner-array transducer (MyLab™25Gold, Esaote, Genova, Italy).6 A 25-gauge, 2-inch needle was used, without the administration of a local anesthetic throughout the procedure. At the scaphoid-pisiform level, the MN was observed at the inlet of the carpal tunnel. In the short-axis group, we used 2 mL NS to hydrodissect the MN from the SSCT with an in-plane ulnar approach. A residual 3 mL NS was delivered to detach the MN from the FR (Figure 1a to c). In the long-axis group, a total of 5 mL NS was delivered into the intracarpal canal with an in-plane approach to detach the MN from the FR advancing from the wrist crease to the palm (Figure 1d to f).