Dorsal Endoscopic Rhizotomy for Chronic Nondiscogenic Axial Low Back Pain

Published on 11/04/2015 by admin

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65 Dorsal Endoscopic Rhizotomy for Chronic Nondiscogenic Axial Low Back Pain

Introduction

Traditional treatment of low back pain from an aging spine encompasses many techniques. When surgery is contemplated, diskectomy, laminectomy, and fusion are the most common surgical procedures utilized. Diskectomy, the most common surgical procedure for sciatica and back pain, may exacerbate the back pain, especially when there is concomitant spinal instability. Chronic back pain may therefore be a consequence following surgical diskectomy. Natural progression of the degenerative process also results in lumbar spondylosis, facet arthrosis, spinal stenosis, and spondylolisthesis in the time line of an aging spine, which may also be the source of pain generation. The costs of surgical procedures to correct these conditions vary widely, depending on the surgical procedures chosen and implemented by the surgeon. Fusion, the traditional procedure for back pain, is usually recommended with caution because of its surgical morbidity and high cost. Failed back surgery syndrome (FBSS), with a paucity of effective salvage procedures, then result when surgical treatment fails. One recent study by Katz1 estimated that the annual costs associated with all treatments of back pain in the United States are over $100 billion. This cost estimate does not even consider the difficult-to-calculate economic loss due to loss of productivity from disabling low back pain. Back surgeries to relieve back pain, however, continue to steadily increase in the United States, partly because of expansion of surgical techniques and implants used to facilitate fusion. Hazard2 documented an increase in these numbers from 300,413 in 1994 to 392,948 in 2000. Though the majority of these surgeries are successful in relieving back pain, a significant percentage is not. Some studies estimate that, at best, only 60% of these surgeries are successful.3,4 These data, along with the data reported in the Spine Outcomes Research Trial (SPORT),5 demonstrate that although most spine surgeries are cost-effective, even the 2-year results for degenerative spondylolisthesis, the premier indication for one-level fusion, is questioned. With good patient selection, accurate diagnostic criteria, and a low cost, a minimally invasive surgical option, addressing just the innervation of the facet-mediated pain generator, may be a viable minimally invasive procedure to be considered before the definitive surgical fusion or joint replacement option is considered.

The Yeung Endoscopic Spine Surgery (YESS) decompressive approach, described in Chapter 64, details a transforaminal endoscopic approach that utilizes a minimally invasive surgical technique enabling disc and foraminal decompression as well as ablation of painful nerves and removal of chemical mediators in the disc, annulus, and foramen. Presumed primary sensory nerves innervating the disc and facet can be ablated, and pathologic conditions causing inflammation (and, therefore, pain) are addressed. The technique, expanded to target denervation of the branches of the dorsal ramus responsible for facet mediated pain, is the subject of this chapter.

Lumbar spondylolysis, facet arthrosis, spondylolisthesis, both isthmic and degenerative, that may also be associated with spinal stenosis, are traditionally treated with open decompression, dynamic stabilization, or fusion. A recent article by Weinstein et al,5 examining the data from the SPORT trial, concluded that degenerative spondylolisthesis surgery (decompression and fusion) is not a cost-effective procedure when examined over a 2-year period. These data highlight the need to better evaluate back pain patients with more specific diagnostic procedures, such as evocative diskography, selective nerve root blocks, foraminal epidural steroids, and facet and medial branch blocks. The information obtained from these procedures in experienced hands allows the surgeon to more selectively choose who might benefit from surgical intervention. Many of the pain generators can also be addressed earlier in the disease process if surgery does not cause significant paradoxical effect on the aging spine. In this chapter we outline a technique for performing endoscopic medial, intermediate, and lateral branch rhizotomy arising from the dorsal ramus, a sensory branch from the origin of the main spinal nerve, that we have termed, dorsal endoscopic rhizotomy.

The endoscopic applications outlined in this chapter are therefore applicable to all painful conditions arising from the facet joint complex.

Indications and Contraindications

Endoscopic rhizotomy has been performed successfully, and remains effective at over 3-year follow-up in most patients in our pilot study. It is appropriate for the following conditions causing axial back pain.

Relative Indications

Patients in the following categories should expect only partial relief of axial back pain from dorsal ramus rhizotomy:

Patients with Poor Indications for Dorsal Ramus Rhizotomy

Patients with lumbosacral radiculopathy whose debilitating leg pain is greater than back pain:

Patients initially benefiting from dorsal endoscopic rhizotomy, who have recrudescence of some of their back pain, may have pain from progression of vertical load forces shifting to the facets, such as progressive degenerative scoliosis. These patients will have relief for 2 to 3 years before the effect of rhizotomy fails. Spinal pain, however, may also come from multiple causes and multiple anatomic structures in the spine. Certain conditions such as anomalous nerves in the foramen may not be detectable using currently available technology, but may be visualized endoscopically. For a structure to be implicated, it needs to be shown to be a source of pain from reliable diagnostic techniques. Endoscopic examination of the foramen during foraminal surgery, discussed in Chapter 64 on foraminal surgery for painful conditions of the lumbar spine, identifies some of these nerve structures and anomalies. The known structures responsible for pain in the spine include, but are not limited to, the vertebral bodies, intervertebral discs, nerve roots, facet joints, ligaments, muscles, and sacroiliac joints. Postlaminectomy syndrome (FBSS) following operative procedures may affect these structures, and, except for recurrent disc herniation or lateral recess stenosis, may not be surgically correctable. Contraindications for facet rhizotomy are pain syndromes not involving the facet joint in some way. Neural blockade or nerve block therapy, however, is a validated procedure that, when performed properly, can implicate the facet joint as responsible for spinal pain in up to 40% of patients with low back pain.7

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