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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 (anteroposterior 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. [ABSTRACT FROM AUTHOR]

Objective The purpose of this study was to compare the reliability of the lateral fluoroscopic view and several contralateral oblique ( CLO) views at different angles in visualizing and accurately predicting the position of the needle tip at the point of access in the posterior cervical and cervicothoracic epidural space. Design After the epidural space was accessed but before confirmation with contrast fluoroscopy, we prospectively obtained fluoroscopic images at eight different angles. Subsequent contrast injection confirmed epidural spread. Needle tip visualization and location of needle relative to bony landmarks were analyzed. Results The needle tip was clearly visualized in all CLO projections in all 24 subjects. CLO view at 50 degrees and at obliquity measured on magnetic resonance imaging ( MRI) images provided the most consistent needle tip location. In these views, the epidural space was accessed at or just beyond the ventral laminar margin at the ventral interlaminar line or within the proximal half of the predefined CLO area in all patients. The needle tip was poorly visualized in the lateral view and the location of the needle tip was less well defined and independent of the needle location in the anteroposterior ( AP) view. Conclusions This study provides evidence that during cervical and cervicothoracic epidural access, the CLO view at 50 degrees and at MRI-measured obliquity is superior to the lateral view for the purpose of needle tip visualization and in providing a consistent landmark for accessing the epidural space. This article also introduces the concept of zones to describe needle position in the cervical and cervicothoracic spine in AP, lateral, and oblique views. [ABSTRACT FROM AUTHOR]