Contrast Spread Technique: Evolution

The recognition of needle entry into an epidural space is a pivotal moment in cervical, thoracic, or lumbar epidural injections. Its significance cannot be overestimated. Regardless of how experienced you are, realizing that you are approaching an epidural space makes your heart beat faster. The safety of the procedure and its success rate depends upon proper and reliable identification of the needle entering into the epidural space. Recent advances in our understanding of fluoroscopic guidance allow pain practitioners to safely place the needle close to the ventral interlaminar line (VILL) [1–4]. However, recognition of the needle exiting the ligamentum flavum and entering into the epidural space was until now performed with the art of the loss of resistance technique (LORT). To rely upon LORT, a practitioner has to master his tactile sensation of change in resistance to the level of an expert. The contrast spread technique (CST) [5], on the contrary, depends upon the knowledge and ability to utilize fluoroscopy to recognize needle depth. We use various fluoroscopic views, and our understanding of clinical anatomy, to create a three-dimensional visualization of the needle tip inside the human body, and to answer the following questions: how close is the needle tip to the epidural space, and how far is it from the midline?