Lumbar Discography and Intradiscal Treatment Techniques



Lumbar Discography and Intradiscal Treatment Techniques





Overview

Discography is a diagnostic test in which radiographic contrast is injected into the nucleus pulposus of the intervertebral disc. Although originally developed for the study of disc herniation, discography is now used most commonly to identify symptomatic disc degeneration. There are two components of discography: (a) the anatomic appearance of contrast spread within the disc (using plain radiographs and/or computed tomography [CT]) and (b) the presence or absence of typical pain during contrast injection within the disc (pain provocation). The usefulness of discography remains controversial, and the last several years have seen an increase in the level of this controversy. Some clinicians continue to routinely use discography to identify symptomatic discs prior to surgical fusion, while others believe the test is of unproven benefit in identifying symptomatic discs. Discography remains the only test available that attempts to correlate pain response from the patient during provocation with abnormal discs discovered on imaging studies. Improved surgical outcomes following lumbar fusion have been reported when guided by the use of discography. However, a recent 10-year retrospective case-control study suggested that patients who underwent diagnostic discography had accelerated disc degeneration, disc herniation, loss of disc height and signal, and the development of reactive endplate changes compared to match-controls involving the control (normal) disc involved in the diagnostic discography procedure. Intradiscal electrothermal therapy (IDET) is a minimally invasive procedure that offers an alternative treatment to a subset of those patients with discogenic low back pain. Much like its use prior to fusion, discography is used to identify symptomatic intervertebral discs prior to IDET. During the past few years, close examination of the existing evidence has produced conflicting results, as the available controlled trials of IDET have produced conflicting results. The use of IDET in the treatment of symptomatic degenerative disc disease has declined dramatically in recent years. A description of IDET has been retained in this edition, as the technique remains available for clinical use. Several other intradiscal techniques have emerged, but the available evidence remains inconclusive. Among these techniques is plasma disc decompression (PDD), a technique that uses radiofrequency technology to reduce intradiscal pressure and treat patients with persistent radicular pain associated with small, contained disc herniations and disc bulges. One controlled trial is now available for this treatment technique and it is described in this chapter. Symptomatic degenerative disc disease remains common and the available treatments are unsatisfactory; undoubtedly, new intradiscal techniques will be developed in the near future.


Anatomy

The intervertebral discs are comprised of glucosaminoglycans with a relatively fluid inner nucleus pulposus surrounded by a stiff, lamellar outer annulus fibrosis. With aging, the hydration of the intervertebral discs declines, leading to loss of disc height and fissure formation in the annulus fibrosis. These fissures begin centrally near the border between the nucleus pulposus and the annulus fibrosis and can extend to the periphery of the disc space. This process of degradation is called internal disc disruption and is believed to be responsible for producing discogenic pain. These same radial fissures within the annulus represent paths through which nuclear material can pass and extrude as a herniation of nucleus pulposus. When this extruded material is adjacent to an exiting spinal nerve, it can lead to intense inflammation, spinal nerve compression, and radicular pain with or without radiculopathy (spinal nerve dysfunction in the form of numbness, weakness, and/or loss of deep tendon reflexes).


The lowest three lumbar intervertebral discs (L3/L4, L4/L5, and L5/S1) are most commonly associated with discogenic pain. The disc spaces at these levels can be entered safely using an oblique approach by placing a needle that passes near the junction of the transverse process and the superior articular process of the vertebra bordering the inferior aspect of the disc space to be studied. The needle then passes medially and inferior to the exiting spinal nerve to penetrate the posterolateral aspect of the annulus en route to the center of the disc space (Fig. 9-1). The L3/L4 disc space lies close to the axial plane, whereas the plane of the L4/L5 and L5/S1 discs follows the lumbar lordosis and is angled progressively in a cephalad-caudal direction. A clear grasp of the plane in which each disc is typically found and accurate alignment of the C-arm are essential to carrying out discography safely and successfully.






Figure 9-1. Anatomy of the lumbar intervertebral discs (lateral view) during lumber discography. In general, the L3/L4 disc lies close to the axial plane, the L4/L5 disc is angled caudally 0 to 15 degrees, and the L5/S1 disc is angled caudally 25 to 35 degrees. Needles can be safely inserted into each disc through the posterolateral aspect of the annulus fibrosis, just caudal and medial to the spinal nerve, which traverses from just inferior to the pedicle within the intervertebral foramen in an anterior, lateral, and inferior direction.


Patient Selection

The patient with low back or neck pain originating from the vertebral disc often presents with deep, aching, axial midline pain. Pain can be referred to the buttocks and posterior thigh from lumber discs but does not extend to the distal extremities. Patients with discogenic pain are often young and otherwise healthy; discogenic pain is common in those with jobs that require repetitive motion of the affected spine segment (e.g., package handlers) or that expose the spine to excessive vibration (e.g., longdistance truck drivers, helicopter pilots, jackhammer operators). Onset of symptoms is usually gradual. Pain is experienced with prolonged sitting (sitting intolerance), standing, and bending forward. The referred pain usually remains in the proximal part of the extremity. Results of physical examination are nonspecific, with limited range
of motion at the affected segment or pain with movement, particularly on flexion. Magnetic resonance imaging (MRI) and CT reveal only nonspecific findings, such as loss of disc height and/or hydration; these findings are often present without pain. The presence of a highintensity zone on MRI at the posterior aspect of the disc indicates that a radial tear or fissure may be present in the annulus fibrosis, a nonspecific finding commonly found in those without back pain. Treatment for discogenic pain starts with conservative therapy, including physical therapy and oral nonsteroidal anti-inflammatory drugs (NSAIDs). In those with prolonged or disabling pain that is suspected to be of discogenic origin, provocative discography can help identify the affected level and guide targeted therapy. Patient selection for IDET and PDD is critical to assuring any benefit, as both procedures have shown modest benefits but only in highly selected patients. The selection criteria for these two intradiscal treatment techniques are discussed in the sections describing the techniques below.


Level of Evidence































Quality of Evidence and Grading of Recommendation


Grade of Recommendation/Description


Benefit vs. Risk and Burdens


Methodological Quality of Supporting Evidence


Implications


RECOMMENDATION: Diagnostic discography: Provocative discography may be considered for the evaluation of selected patients with suspected discogenic pain; it should not be used for routine evaluation of a patient with chronic nonspecific back pain.


2C/weak recommendation, low-quality or very lowquality evidence


Uncertainty in the estimates of benefits, risks, and burden; benefits, risk, and burden may be closely balanced


II-2: Observational studies or case series


Very weak recommendations; other alternatives may be equally reasonable


RECOMMENDATION: Intradiscal Electothermal Therapy (IDET): IDET may be considered for young active patients with early single-level degenerative disc disease with well-maintained disc height.


2C/weak recommendation, low-quality or very lowquality evidence


Uncertainty in the estimates of benefits, risks, and burden; benefits, risk, and burden may be closely balanced


I: Randomized controlled trials (RCTs) with important limitations (inconsistent results, methodological flaws, indirect, or imprecise) and strong evidence from observational studies


Very weak recommendations; other alternatives may be equally reasonable


RECOMMENDATION: Percutaneous Disc Decompression (PDD): PDD may be considered for patients with small (<3 mm) contained disc herniations and persistent radicular pain.


2B/weak recommendation, moderate-quality evidence


Benefits closely balanced with risks and burden balanced


I: Randomized controlled trials (RCTs) with important limitations (inconsistent results, methodological flaws, indirect, or imprecise) and strong evidence from observational studies


Weak recommendation, best action may differ depending on circumstances or patients’ or societal values


The use of diagnostic discography has evolved rapidly in recent years. The addition of pressure monitoring during injection has become widespread and undergone careful scientific validation, and a number of more recent clinical trials have incorporated discography into patient selection criteria for treatment. Yet, the usefulness of this diagnostic test remains in question: advocates point to the fact that pain on provocation is highly suggestive as the disc as a source of pain and critics emphasize the subjective nature of the test and lack of a gold standard for validation. Emerging evidence from retrospective study suggests that there is accelerated disc degeneration within the disc that was previously normal (the control disc) over the decade following diagnostic discography. There are no definitive answers, but the controversy has led to a decline in the use of discography as a diagnostic test. Nonetheless, many practitioners and clinical investigators still rely on discography as the best available means to select patients with symptomatic degenerative disc disease for targeted treatment.

In no area of interventional pain is disagreement more apparent than when discussing expert recommendations regarding use of diagnostic discography. The American Pain Society (APS) Low Back Pain Guideline Panel published a report in 2009, concluding, “In patients with chronic nonradicular low back pain, provocative discography is not recommended as a procedure for diagnosing discogenic low back pain (strong recommendation, moderate-quality evidence).” Subsequently, the American Society of Anesthesiologists (ASA) Task Force on Chronic Pain Management published A 2010 Practice Guideline, offering the following recommendation: “Provocative discography may be considered for the evaluation of selected patients with suspected discogenic pain; it should not be used for routine evaluation
of a patient with chronic nonspecific back pain.” Both guideline panels considered the same body of scientific evidence. The APS group cited the lack of any available gold standard against which to validate discography and the significant complications associated with the test, while the ASA group focused on the small number of uncontrolled trials suggesting that discography allows for improved patient selection for invasive treatments, including surgical lumbar fusion.

IDET has also been the subject of much debate. Two moderate-sized RCTs appeared during this decade, one demonstrating modest long-term reduction in back pain in a subset of patients and a second showing no benefit when compared to sham treatment; both trials were limited to patients with early degenerative disc disease at a single disc who reported concordant symptoms during discography. Several observational trials do suggest modest reduction in pain after treatment with IDET. The 2009 APS Low Back Pain Guideline Panel concluded, “IDET may be considered for young active patients with early single-level degenerative disc disease with well maintained disc height.” The 2010 ASA Task Force on Chronic Pain Management made the following recommendation: “There is insufficient evidence to adequately evaluate benefits of … intradiscal electrothermal therapy (IDET) … for nonradicular low back pain.” Despite the suggestive evidence that IDET may provide some pain reduction in young, active patients with early degenerative disc disease, many third party payers in the United States have eliminated reimbursement for this treatment and there has been a sharp decline in its use.

There are a number of emerging treatments for discogenic pain including the application of thermal energy to the annulus, injection of growth factors within the nucleus pulposus, or the injection of fibrin “glue” within the central disc: All await clinical validation. While no recommendations can be made about these treatments today, it seems more likely than not that some form of therapy requiring percutaneous access to the intervertebral discs will emerge from current scientific development efforts. Thus, the skills needed to place a needle within the intervertebral disc that are described in this chapter are likely to remain a core part of the skill set of interventional pain specialists.

Among intradiscal treatments that have undergone direct clinical validation, PDD is among the few, and thus it has been included in this discussion of intradiscal treatments. A single multicenter trial comparing the efficacy of PDD with transforaminal injection of steroids was conducted in patients with small, contained disc herniations and persistent radicular pain. The trial showed sustained reductions in leg pain and improvements in physical function during the 2-year follow-up period that were superior in those treated with PDD when compared to those receiving transforaminal steroid injections. It is important to emphasize that the group treated was highly selected: patients with small (<3 mm) disc protrusions and predominance of ongoing leg pain. Most patients with such small disc herniations are asymptomatic, and this group represents just 5% to 10% of patients with radicular symptoms. It is also important to emphasize that PDD is not meant to be used for the treatment of discogenic pain.


Diagnostic Lumbar Discography


Positioning

Lumbar discography is a painful procedure, even when performed by the most skilled practitioners. Intravenous sedation can facilitate the procedure; however, caution must be used to avoid oversedation, which could impede ongoing communication with the patient. The patient must be able to report paresthesiae before neural injury occurs. Discography also relies on the patient to report the location and severity of symptoms during provocation; thus, excessive sedation can make interpretation of the results difficult. The patient lies prone, with the head turned to one side (Fig. 9-2). A pillow is placed under the lower abdomen, above the iliac crest, in an effort to reduce the lumbar lordosis. Asking the patient to rotate the inferior aspect of the pelvis anteriorly toward the table will tip the iliac crests posteriorly and is often key to successfully performing discography at the L5/S1 level. The C-arm is rotated 25 to 35 degrees obliquely and centered on the disc space to be studied. The C-arm is then angled in a cephalad direction, the degree of which will vary from patient to patient, depending on the disc to be studied and each patient’s degree of lumbar lordosis (see Fig. 9-2). In general, the L3/L4 disc lies close to the axial plane and requires no cephalad angulation to align the vertebral endplates (Fig. 9-3), the L4/L5 disc requires 0 to 15 degrees of cephalad angulation, and the L5/S1 disc requires 25 to 35 degrees of cephalad angulation (Fig. 9-4). Proper alignment of the C-arm is critical to the safety and success of discography.


Block Technique

The skin and subcutaneous tissues overlying the disc space where discography is to be carried out are anesthetized with 1 to 2 mL of 1% lidocaine, and additional local anesthetic is instilled liberally as the needle is advanced. A 22-gauge, 5-inch spinal needle is placed through the skin and advanced until it is seated in the tissues in a plane that is coaxial with the axis of the x-ray path (Figs. 9-3, 9-4 and 9-5). A 7- or 8-inch spinal needle is often required in obese patients and is often needed at the L5/S1 level due to the long and oblique trajectory to the disc space. Without careful use of a coaxial technique throughout the entire course of needle advancement, discography will require redirecting the needle multiple times, if it can be done successfully at all. The direction of the needle should be rechecked after every 1 to 1.5 cm of needle advancement and adjusted to remain coaxial. The position of the exiting spinal nerve beneath the pedicle should be kept in mind at all times, and efforts to
ensure the needle does not stray cephalad or lateral to the intended point over the middle of the disc will reduce the likelihood of striking the spinal nerve en route to the disc (Figs. 9-6 and 9-7). Once the needle is in contact with the surface of the disc, there will be a notable increase in resistance to needle placement. At this point, the C-arm should be rotated to a lateral position, and the needles should be advanced halfway from the anterior to the posterior margin of the disc (Fig. 9-8). Proper final placement is then checked in the anterior-posterior (AP) plane, where again the needle should be in the midportion of the disc space (Fig. 9-9). The nucleus pulposus occupies the central onethird of the disc space, and placement of the needle tip anywhere within the nucleus should suffice. The final needle path lies inferior to the exiting spinal nerve, and in many patients, it is difficult or impossible to position the needle exactly in the center of the disc (see Figs. 9-6 and 9-7).






Figure 9-2. Position for lumbar discography. The patient is placed prone with the head turned to one side. The C-arm is rotated 25 to 35 degrees obliquely and centered on the disc space to be studied. The C-arm is then angled in a cephalad direction that will vary from patient to patient, depending on the disc to be studied and each patient’s degree of lumbar lordosis. In general, the L3/L4 disc lies close to the axial plane and requires no angulation to align the vertebral endplates, the L4/L5 disc requires 0 to 15 degrees of cephalad angulation, and the L5/S1 disc requires 25 to 35 degrees of cephalad angulation.

Once the needles are in final position at all levels to be tested, provocative testing is conducted. A small volume of radiographic contrast containing antibiotic is placed at each level (<1.5 mL of iohexol 180 mg per mL containing 1 mg per mL of cefazolin). The contrast material is injected under live fluoroscopy to observe the pattern of contrast spread within the disc (Fig. 9-10

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May 26, 2016 | Posted by in ANESTHESIA | Comments Off on Lumbar Discography and Intradiscal Treatment Techniques
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