Lumbar discography

Abstract

Study design: A comprehensive review of the literature dealing with lumbar discography was conducted.

Objective: The purpose of the review is to update the North American Spine Society position statement published in 1994 that addressed criticisms of lumbar discography, to identify indications for Summary of background data: Lumbar discography remains a controversial diagnostic procedure. There are concerns about its safety and clinical value, although many support its use in specific applications.

Methods: Articles dealing with lumbar discography were reviewed and are summarized in this report.

Results: Most of the recent literature supports the use of discography in selected patients. Although not to be taken lightly, many of the serious complications and high complication rates reported before 1970 have decreased since then because of improvement in injection technique, imaging and contrast materials.

Conclusions: Most of the current literature supports the use of discography in select situations. Indications for discography include, but are not limited to:

1. Further evaluation of demonstrably abnormal discs to help assess the extent of abnormality or correlation of the abnormality with the clinical symptoms. Such symptoms may include recurrent pain from a previously operated disc and lateral disc herniation.

2. Patients with persistent, severe symptoms in whom other diagnostic tests have failed to reveal clear confirmation of a suspected disc as the source of pain.

3. Assessment of patients who have failed to respond to surgical intervention to determine if there is painful pseudarthrosis or a symptomatic disc in a posteriorly fused segment and to help evaluate possible recurrent disc herniation.

4. Assessment of discs before fusion to determine if the discs within the proposed fusion segment are symptomatic and to determine if discs adjacent to this segment are normal.

5. Assessment of candidates for minimally invasive surgical intervention to confirm a contained disc herniation or to investigate dye distribution pattern before chemonucleolysis or percutaneous procedures.

Lumbar discography should be performed by those well experienced with the procedure and in sterile conditions with a double-needle technique and fluoroscopic imaging for proper needle placement. Information assessed and recorded should include the volume of contrast injected, pain response, with particular emphasis on its locations and similarity to clinical symptoms, and the pattern of dye distribution. Frequently, discography is followed by axial computed tomography scanning to obtain more information about the condition of the disc.

Introduction

Discography involves the injection of radiographic contrast into the nucleus of an intervertebral disc. During the injection, the physician performing the procedure asks the patient if the injection generates pain similar to his/her “usual pain.” Discographic images are generated from plain radiographs and computed tomography (CT) scanning in the axial plane. In 1988, the Executive Committee of the North American Spine Society (NASS) published a position statement on discography [1], which later was criticized in an editorial in Spine [2]. The criticism centered on the invasiveness of the procedure and whether the information gained justified associated risks. Proponents of discography contend that pain provocation by disc injection is sometimes the only method that can differentiate which disc is responsible for the patient's symptoms and that the discographic image can demonstrate lesions not revealed by other methods. As in the previous Contemporary Concepts paper on discography [3], in this article we analyze the literature related to discography to determine current, appropriate indications and to evaluate previously published criticisms. In doing so, we note that the procedure currently performed is very different from that performed years ago.

Pain at the time of injection is evaluated in terms of location and similarity to clinical symptoms. One method of pain classification is as follows: no pain or pressure only, pain dissimilar to clinical symptoms, pain similar to clinical symptoms or exact reproduction of symptoms [4].

Pain intensity may be recorded on a scale of 1 to 10 points. Unfortunately, some studies have failed to report on the pain provocation entirely or restricted the information to whether pain was provoked or not, without comparison to clinical symptoms.

In a normal disc, dye remains in the nucleus and appears as a “cotton ball.” In a herniated disc, dye outlines the fissure to or through the outer annulus. Contrast spreads throughout a diffusely degenerated disc, and the disc space may appear narrow on the lateral radiograph. Published studies differ in the definition of an “abnormal” discogram so that in reviewing articles, one must carefully assess technique and the basis of the interpretation. The current standard for a discogram to be considered “positive” (that is, abnormal) is pain that is similar or exactly like the patient's clinical pain that is provoked with the injection, and the radiographic image of the disc must be abnormal.

If a large volume of contrast can be injected, the disc is degenerated or a fissure extends through the outer annular wall. Injection pressure or resistance to the injection should be noted. An experienced discographer can determine a relative resistance to the injection. Low resistance is generally associated with a tear through the outer annulus. Newer techniques, such as discomanometry, seek to standardize the pressurization.