Objective. The purpose of this study was to perform a comparative analysis of the contralateral oblique (CLO) view and the lateral view for lumbar interlaminar epidural access.
Design. After the epidural space was accessed, fluoroscopic images at eight different angles (antero-posterior view, multiple CLO, and lateral view) were prospectively obtained. Visualization and location of needle tip relative to bony landmarks were analyzed. The epidural location of the needle was subsequently confirmed by contrast injection and analysis in multiple views.
Results. Visualization of the needle tip and the relevant radiologic landmarks was superior in the CLO view. The needle tip location in the epidural space was most consistent at a CLO angle of 45°.
Conclusion. This study shows that the CLO view for lumbar interlaminar epidural access offers clear advantages over the lateral view on many clinically important grounds: the needle tip visualization is better, the important radiological landmarks are better visualized, and the needle tip when placed in the epidural space presents a more precise relationship to these landmarks. All of these differences were highly significant. Thus, when using this view, the needle may be directly placed in very close vicinity to the epidural space and true loss of resistance expected soon thereafter. In addition, this view provides the ability to plot the cranio-caudad needle trajectory. The combination of these factors is likely to improve the ease and efficiency of epidural access. The crisp visualization of the final moments of epidural access could also translate to improved safety and accuracy. In light of this, it is suggested that a CLO view at 45° be considered the preferred view for gauging needle depth during interlaminar lumbar epidural access.