NEEDLE TIP DEPTH ASSESSMENT ON FORAMINAL OBLIQUE FLUOROSCOPIC VIEWS DURING CERVICAL RADIOFREQUENCY NEUROTOMY. A TECHNICAL NOTE

Abstract

Background: Precise needle tip visualization using fluoroscopy is critical to avoid injury to nearby neurovascular structures during cervical radiofrequency neurotomy (RFN). The contralateral oblique (CLO) view has been shown to be superior to the lateral view for needle tip visualization during cervical interlaminar epidural injection (CESI). It has been demonstrated that increasing the angle of obliquity during CESI causes the needle tip to appear to move dorsal and superficial on contralateral oblique views. Needle tip visualization for cervical RFN has been described using a foraminal oblique (FO) view, but the technique and effect of angle on needle tip depth have not been studied. Objective: To analyze how the needle tip depth changes with varying oblique angles of FO views during cervical RFN. Methods: Fluoroscopic views during cervical RFN between lateral and 50 degrees FO in a single subject were analyzed. Results: The needle tip appears to move ventral and deeper with increasing angle of obliquity with respect to the lamina. Conclusion: Contrary to the phenomenon noticed with contralateral oblique views in CESI, in this case the needle tip appears to move ventral and deeper with increasing angle of obliquity on foraminal oblique views during cervical RFN. It becomes crucial for practitioners to understand that during cervical RFN, with inadequate foraminal oblique angle, needle tip looks artificially superficial, which in turn may cause one to advance the needle to a dangerous depth. Limitation: This is an observational study in a single subject; hence further larger studies are needed to confirm the findings in this technical report. Key words: contralateral oblique, needle depth assessment, cervical radiofrequency neurotomy, cervical radiofrequency ablation, foraminal oblique, fluoroscopy views, fluoroscopy angles