Hemidiaphragmatic Paresis Following Interscalene Brachial Plexus Block With 2-Point Injection Technique.

Background: An interscalene brachial plexus block is a commonly conducted nerve block for anesthesia and analgesia in shoulder surgery. Due to its proximity to the targeted nerve, the phrenic nerve, which innervates the diaphragm, is typically inadvertently blocked by ventral spread of the local anesthetic. Although hemidiaphragmatic paresis is tolerable in healthy patients, it would be an irreversible risk to patients with compromised lung reserve.

Retrospective lumbosacral CT analysis and prospective observational study of the ipsilateral tunnel view technique for fluoroscopy-guided selective S1 transforaminal epidural injection.

Background: The purpose of this study was to retrospectively observe the anatomic relationship between dorsal S1 foramen (DS1F) and ventral S1 foramen (VS1F) through computed tomography (CT) analysis and to prospectively determine the optimal angle of ipsilateral tunnel view technique for performing S1 transforaminal epidural steroid injection (S1-TFESI).

Methods: The axial lumbosacral CTs taken between in 208 consecutive patients and the following measurements were obtained on both sides: (1) the α-angle was defined as an angle between a sagittal line passing through the center of the sacrum and an imaginary line passing through the center of DS1F, (2) the largest diameter of DS1F and VS1F. The fluoroscopy was adjusted to show the largest L5/S1 intervertebral disc space, which was defined as the cephalad angle, and tilted to the ipsilateral oblique side until the entrance of DS1F had a well-defined, round shape, which defined as the β-angle in 40 humans.