#534 Endoscopically Guided Dorsal Rhizotomy Is More Effective Than Pulsed Radiofrequency Lesioning for Non-discogenic Axial Back Pain
MIS Techniques and Outcomes
Poster Presented by: A. Yeung
A.T. Yeung (1)
Y. Zheng (1)
(1) Desert Institute for Spine Care, Phoenix, AZ, USA
Introduction: A more effective endoscopically visualized guided technique for dorsal rhizotomy is for axial back pain.
Method: A prospective non-randomized pilot feasibility study of 50 patients, initiated in 2006 demonstrated superiority over pulsed radio frequency. Patients with lumbar spondylosis and facet arthrosis on MRI presenting with predominant axial back pain who had at least 50% pain relief by medial branch blocks met the inclusion criteria. The initial study was expanded each year, now totaling over 400 patients. Minor modifications of the original 2006 surgical technique evolved, due to the ability to surgically explore the dorsal column for patho-anatomy. Endoscopic exploration of the vicinity of the dorsal ramus the facet wall was possible. The surgical technique was guided by findings in our cadaver dissections identifying variable location and anatomy of the branches of dorsal ramus and it's branches. In some cases, the dorsal ramus is encountered.
Results: A 90% Excellent/Good result was obtained, providing pain relief equal or greater than the injection. No patient was worse. At one year follow-up, Pre-op vs post scores averaged: VAS 6.2-2.5, and ODI 48-28. These indices remained relatively constant even when additional surgical cases were added to the database. The patient's degree of pain was consistently equal or greater than the relief obtained with the medial branch blocks. Most patients had greater relief after rhizoztomy. The Patients requesting repeat endoscopic lesioning in the 1-6 year follow-up period were also helped. No patient was worse. There were no permanent complications, although a few patients experienced mild temporary dysesthesia. With yearly follow-up, less than10 percent experienced partial return of their back pain, but most were still satisfied with use of medication and activity modification. Patients requesting repeat rhizotomy still experienced similar, but lesser improvement from the index procedure. Rhizotomy of the upper lumbar facets were also beneficial, but not as consistent nor better than relief received from medial branch blocks at the lower lumbar spine from L3-S1.
Discussion: The cadaver studies demonstrated considerable variability in the location of the branches in each cadaver specimen. The cadaver studies gave further appreciation of the role of the dorsal ramus ventral to the intertransverse ligament. Neuromas of the dorsal ramus has been identified endoscopically. In the upper lumbar spine, the standard anatomic relationships illustrated in peer reviewed publications did not hold up. We were not able to find the medial branch to the facet as consistently as explained in the spine literature. The nerve to the facet joint, because it is more cephalad to the transverse process, did not traverse the transverse process. Nerve Ablation at these two levels may require lesioning of the dorsal ramus or targeting the medial branch on the facet capsule. The side firing laser was helpful in ablation of the lateral facet capsule. A bi-tip bipolar probe for facilitated soft tissue ablation. Laser allowed for more through ablation of the facet wall.
Conclusion: Endoscopically guided rhizotomy provides more effective and consistent results than pulsed radiofrequency. It provides better, and longer lasting results. The variations in the location of facet innervation as demonstrated in cadaver dissections dictates a need for visually guided endoscopic MIS surgery.