2009 ISSLS Prize Winner: Does Discography Cause Accelerated Progression of Degeneration Changes in the Lumbar Disc: A Ten-year Matched Cohort Study

Eugene J. Carragee, MD; Angus S. Don, FRACS; Eric L. Hurwitz, DC, PhD; Jason M. Cuellar, MD, PhD; John Carrino, MD; Richard Herzog, MD

Disclosures

Spine. 2009;34(21):2338-2345. 

In This Article

Abstract and Introduction

Abstract

Study Design: Prospective, match-cohort study of disc degeneration progression over 10 years with and without baseline discography.
Objectives: To compare progression of common degenerative findings between lumbar discs injected 10 years earlier with those same disc levels in matched subjects not exposed to discography.
Summary of Background Data: Experimental disc puncture in animal and in vivo studies have demonstrated accelerated disc degeneration. Whether intradiscal diagnostic or treatment procedures used in clinical practice causes any damage to the punctured discs over time is currently unknown.
Methods: Seventy-five subjects without serious low back pain illness underwent a protocol MRI and an L3/4, L4/5, and L5/S1 discography examination in 1997. A matched group was enrolled at the same time and underwent the same protocol MRI examination. Subjects were followed for 10 years. At 7 to 10 years after baseline assessment, eligible discography and controlled subjects underwent another protocol MRI examination. MRI graders, blind to group designation, scored both groups for qualitative findings (Pfirrmann grade, herniations, endplate changes, and high intensity zone). Loss of disc height and loss of disc signal were measured by quantitative methods.
Results: Well matched cohorts, including 50 discography subjects and 52 control subjects, were contacted and met eligibility criteria for follow-up evaluation. In all graded or measured parameters, discs that had been exposed to puncture and injection had greater progression of degenerative findings compared to control (noninjected) discs: progression of disc degeneration, 54 discs (35%) in the discography group compared to 21 (14%) in the control group (P = 0.03); 55 new disc herniations in the discography group compared to 22 in the control group (P = 0.0003). New disc herniations were disproportionately found on the side of the anular puncture (P = 0.0006). The quantitative measures of disc height and disc signal also showed significantly greater loss of disc height (P = 0.05) and signal intensity (P = 0.001) in the discography disc compared to the control disc.
Conclusion: Modern discography techniques using small gauge needle and limited pressurization resulted in accelerated disc degeneration, disc herniation, loss of disc height and signal and the development of reactive endplate changes compared to match-controls. Careful consideration of risk and benefit should be used in recommending procedures involving disc injection.

Introduction

The iatrogenic causes of progressive disc degeneration include direct surgical trauma, iatrogenic disc infection, degeneration next to a long segment fusion, etc. For many years a model of disc degeneration has been used in animals studies, which included the anular puncture of the disc.[1,2,3,4] In some large animal models, small needle gauge puncture has not shown short-term changes,[5] whereas other have.[6] Nonetheless, small needle anular punctures, such as those preformed in discography or intradiscal treatment procedures, are common and controversial procedures.

Whether these intradiscal diagnostic or treatment procedures cause any observable damage to the punctured discs over time is currently unknown. Most practitioners of these techniques estimate the risk of secondary degenerative change to be extremely remote.[7,8,9]

Patients exposed to discography have been followed with plain radiographs without apparent morphologic changes,[10] but no MR images of a similar cohort have been followed. Experimental discography, in volunteer subjects without serious axial pain syndromes have been performed by Holt,[11] Walsh et al,[12] Wood et al,[13] Carragee et al,[14,15,16,17] and Derby et al,[18] among others. Early analysis of some of these subjects has detected increased back pain reported after discography, which attenuates to apparent background levels over 1 or 2 years.[15,19] This effect was primarily seen in subjects with psychological distress at the time of the injection. However, no long-term controlled, clinical, and imaging follow-up of discs exposed to anular puncture and injection has been reported thus far.

The present matched cohort study was performed to provide a definitive evaluation of the risk of progressive disc degeneration and associated findings in subjects exposed to a modern technique, 3-level discography procedure using limited pressurization. This discography group was tested at baseline and compared up to 10-years later, using a standard lumbar MRI grading protocol and experienced readers. By documenting MR changes over time in this group compared to a closely-matched control group exposed to the same baseline MR and follow-up evaluations (excepting the discography injections), the structural effects, if any, associated with the injection could be investigated. We intended to analyze these data to determine if there were clear differences in progression of common degenerative findings between those discs injected 10-years earlier compared to those same level discs in matched subjects not exposed to discography.

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