Residency · Residency · Chronic Pain Management
Lumbar Discography: Technique and Controversy
Introduction
Provocation discography is a diagnostic procedure designed to identify a specific intervertebral disc as the source of a patient's pain. Unlike imaging studies that reveal only morphologic abnormalities, discography aims to establish a physiologic correlation between disc pathology and clinical symptoms by reproducing the patient's concordant pain upon pressurization. Despite decades of use, discography remains one of the most controversial procedures in interventional pain medicine.
Indications
Discography is considered in patients with persistent axial low back pain unresponsive to conservative therapy when surgical intervention (fusion, disc replacement) is being considered. It is used to identify the symptomatic disc level in patients with multilevel degenerative disc disease on MRI, to assess discs adjacent to a planned fusion to determine whether they are asymptomatic, and to evaluate recurrent pain after prior spine surgery to differentiate between disc-related and non-disc pain generators. Discography is not a first-line diagnostic test and should only be considered after exhaustive noninvasive evaluation.
Technique
Patient Preparation
Intravenous antibiotic prophylaxis (typically cefazolin 1 g) is administered before the procedure to reduce the risk of discitis. Intradiscal antibiotics (such as cefazolin mixed with contrast) are also routinely used. Light sedation may be employed, but heavy sedation must be avoided to preserve the patient's ability to report pain characteristics accurately. The patient is positioned prone on a fluoroscopy table.
Needle Placement
A double-needle technique is preferred: an introducer needle (18-20 gauge) is advanced to the annular surface, followed by a smaller gauge needle (22-25 gauge) into the nucleus pulposus. The approach is typically posterolateral (extrapedicular) under fluoroscopic guidance. On AP fluoroscopy, the needle tip should be at or just past the midline of the disc. On lateral fluoroscopy, the tip should be centered within the nucleus pulposus.
Pressurization and Provocation
Non-ionic contrast medium is slowly injected under manometric control using a pressure-monitored syringe. The injection pressure, volume accepted, and pain response are recorded at each disc level. Opening pressure, provocation pressure, and maximum pressure are all documented. A control disc (a morphologically normal adjacent level) must be tested and should be painless to validate the test.
<image>Step-by-step fluoroscopic illustration of lumbar discography technique showing: (1) AP view with needle trajectory approaching the disc via posterolateral extrapedicular approach, needle tip at midline; (2) lateral view confirming needle tip centered in the nucleus pulposus; (3) post-injection AP and lateral views showing contrast spread patterns within the disc corresponding to different Dallas Discogram Scale grades (grade 0 through grade 5). Each grade is illustrated with its characteristic annular disruption pattern.</image>
Interpretation Criteria
Concordant Pain
A disc is considered positive if pressurization produces pain that the patient identifies as concordant -- meaning it reproduces their typical clinical pain pattern. The pain must be provoked at pressures below 50 psi above opening pressure (per ISIS/SIS guidelines) or at low volumes (less than 3.5 mL). The pain intensity during provocation should reach at least 6/10 on the numeric rating scale. At least one adjacent control disc must be negative (no pain or discordant pain on pressurization) to validate the result.
Dallas Discogram Scale (Modified)
The morphologic component of discography is graded on the Dallas Discogram Scale.
| Dallas Grade | Contrast Extension | Interpretation |
|---|---|---|
| 0 | Confined to nucleus pulposus | Normal |
| 1 | Inner one-third of annulus | Mild annular disruption |
| 2 | Middle one-third of annulus | Moderate annular disruption |
| 3 | Outer one-third of annulus | Significant tear (clinically relevant with concordant pain) |
| 4 | Full-thickness radial tear, beyond outer annulus | Complete annular disruption |
| 5 | Circumferential spread or beyond disc margin | Extensive disruption |
Grade 0 indicates contrast confined to the nucleus pulposus (normal). Grade 1 shows extension into the inner one-third of the annulus fibrosus. Grade 2 shows extension into the middle one-third. Grade 3 reaches the outer one-third. Grade 4 indicates a full-thickness radial tear with contrast extending beyond the outer annulus. Grade 5 shows circumferential spread or extension beyond the disc margin. Concordant pain accompanied by a grade 3 or higher tear is the most clinically significant finding.
Modified Walsh Criteria
A positive discogram under the modified Walsh criteria requires concordant pain provoked at low pressure, with at least one negative control level and an annular tear (grade 3 or higher) on post-discography CT.
False-Positive Rates
The false-positive rate of discography has been a central point of debate. Holt (1968) reported a high false-positive rate in asymptomatic prisoners, though this study has been widely criticized for methodological flaws including the use of ionic contrast and lack of manometric control. Walsh et al. (1990) demonstrated a 0% false-positive rate in asymptomatic volunteers using strict interpretation criteria and modern technique. Carragee et al. (2006) reported 0% false-positive rates in truly asymptomatic individuals but rates as high as 75% in patients with chronic pain, somatization, or prior discectomy.
The core debate is whether pain provocation in a sensitized patient reflects true disc pathology or nonspecific central pain processing. Psychological factors, central sensitization, and prior surgery all significantly increase the likelihood of a false-positive result.
<image>Axial CT discogram illustration showing three discs at different levels: (1) a normal disc with contrast contained within the nucleus pulposus (Grade 0); (2) a disc with a posterior radial annular tear extending to the outer annulus with contrast tracking along the tear (Grade 3); and (3) a disc with circumferential tear and contrast extending beyond the outer annulus (Grade 5). Each image is labeled with the corresponding Dallas Discogram Scale grade and clinical interpretation.</image>
The Controversy
Arguments Supporting Discography
Discography is the only test that directly correlates disc morphology with pain reproduction. MRI findings alone have poor specificity, as asymptomatic individuals frequently demonstrate disc degeneration and high-intensity zone (HIZ) lesions. When performed with strict criteria -- manometric control, concordant pain, and a negative control level -- specificity is high. Surgical outcomes for fusion have been shown to improve when discography confirms the pain source.
Arguments Against Discography
Carragee et al. (2009) published a prospective 10-year study suggesting that discography may accelerate disc degeneration and herniation at punctured levels. The procedure is operator-dependent, and results vary with technique, sedation level, and interpretation criteria. No sham-controlled randomized controlled trial has demonstrated that surgical outcomes guided by discography are superior to those guided by MRI alone. The psychological state of the patient profoundly influences results, making standardization difficult. Discitis, though rare (0.1-0.25% per disc level even with antibiotic prophylaxis), remains a risk.
Post-Discography CT
A CT scan is obtained within 4 hours of discography to delineate annular morphology. It provides detailed assessment of radial tears, annular fissures, and disc contour that may not be visible on MRI. The combination of provocation data and CT morphology provides the most complete diagnostic picture.
Clinical Pearls
Discography should never be performed without manometric pressure monitoring, as uncontrolled injection invalidates the results. At least one morphologically normal control disc must be included and must be painless to confirm test validity. Patients should be screened for psychological comorbidities (depression, somatization, secondary gain) before discography, since these significantly increase false-positive rates. Discography should be viewed as a pre-surgical test rather than a standalone diagnostic tool, and results must be integrated with the full clinical picture. The decision to proceed with discography should involve a shared decision-making discussion about the controversy and limitations of the test.
References
- Walsh TR, Weinstein JN, Spratt KF, et al. Lumbar discography in normal subjects: a controlled, prospective study. J Bone Joint Surg Am. 1990;72(7):1081-1088.
- Carragee EJ, Don AS, Hurwitz EL, et al. 2009 ISSLS Prize Winner: Does discography cause accelerated progression of degeneration changes in the lumbar disc? Spine. 2009;34(21):2338-2345.
- Wolfer LR, Derby R, Lee JE, Lee SH. Systematic review of lumbar provocation discography in asymptomatic subjects with a meta-analysis of false-positive rates. Pain Physician. 2008;11(4):513-538.
- Manchikanti L, Benyamin RM, Singh V, et al. An update of the systematic appraisal of the accuracy and utility of lumbar discography in chronic low back pain. Pain Physician. 2013;16(2 Suppl):SE55-95.
