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Discography’s role in low back pain management
Practice Points
Ryan S Reeves1 & Michael B Furman* Lumbar provocation discography is an ideal clinical test to evaluate and confirm whether or not a
patient’s discs are a source of their axial (nonradicular) pain. Lumbar provocation discography interpretation should include a description of pain response
concordance, manometric pressure data and imaging correlation with fluoroscopic nucleograms and postdiscography computed tomography. Lumbar provocation discography results must be interpreted within the context of a patient’s clinical
scenario and should be utilized after other conservative measures have failed to produce functional benefits. Lumbar provocation discography should be utilized to confirm and circumscribe the lumbar disc as the
axial (nonradicular) pain source before treating with percutaneous or open surgical procedures and/or inclusion in ongoing research protocols. When lumbar provocation discography results are negative, multilevel or unclear for defining the axial
(nonradicular) pain source, percutaneous or open surgical procedures, or inclusion in ongoing research protocols should not be considered.
SUMMARY
Lumbar provocation discography is a commonly used diagnostic procedure utilized to determine the presence or absence of discogenic pain at a specific spinal segment. Although multidisciplinary societies have recognized discography as the primary criterion for identifying discogenic pain, the test remains controversial. Skeptics argue against its sensitivity and specificity, and suggest that it’s risks outweigh any potential benefits. However, when properly performed and interpreted, discography is an invaluable tool. Together with a patient’s history, physical examination and radiological studies, discography will safely identify both symptomatic and asymptomatic discs to provide confirmatory evidence that a particular disc is the source of the patient’s pain. Since information from this study may be used to plan for percutaneous or open surgical procedures, accurate and precise interpretation of the results is vital. Chronic axial low back pain, defined as pain limited to the back without nerve root involvement, is often functionally limiting. For those patients
with chronic axial low back pain who have failed conservative care, it is appropriate to determine whether there is a structural, treatable cause for
Spine Team Texas, Southlake, TX, USA *Author for correspondence: Orthopaedic & Spine Specialists, York, PA, USA; [email protected] 1
10.2217/PMT.11.87 © 2012 Future Medicine Ltd
Pain Manage. (2012) 2(2), 151–157
part of
ISSN 1758-1869
151
Review Reeves & Furman
Figure 1. T2-weighted MRI demonstrating disc dessication and increased signal intensity in the posterior anulus at L5–S1, suggesting that this disc could be a potential pain source.
their pain. Potential sources of chronic axial low back pain include the lumbar discs, zygapophyseal joints, sacroiliac joints and vertebral body compression fractures, amongst others [1] . These should be ruled out as appropriate [2,3] . When
diagnostic tests rule out facet or sacroiliac disease, and history, exam and imaging suggest that one or more lumbar discs are the potential pain generator, discography is clinically warranted, especially after diagnostic tests and procedures have ruled out facet or sacroiliac pathology. This article addresses discography use to assess axial low back pain. For ‘back’ pain which involves a significant component of appendicular or radicular pain into the lower limbs, other diagnostic tools should be considered and are beyond this article’s scope. Discography is usually performed in patients who are considering more invasive treatments such as percutaneous intradiscal or open discal procedures. The procedure is used to identify concordantly painful disc(s) and to verify that adjacent discs are negative for concordant pain prior to a therapeutic interventional procedure or surgery. This provocative test mimics physiologic loads, evoking pain by stimulating nociceptors or pathological innervated annular rents [4] . Pre-procedural diagnostics (Figure 1) , concordant pain provocation during disk pressurization, along with intra- and post-procedural imaging (Figures 2 & 3) , are all used to confirm or refute one’s clinical impression that a specific disc is a pain source. Those with equivocal results or with three or more positive discs are not candidates for further aggressive treatments. Discography controversies False positives or true positives?
Figure 2. Lateral fluoroscopic image of lumbar discography at two levels. Note that the L5–S1 level was positive for concordant pain.
152
Pain Manage. (2012) 2(2)
There is much controversy regarding the utilization of lumbar discography. Lumbar provocation discography has been a commonly used diagnostic procedure utilized to determine the presence or absence of discogenic pain at a specific spinal segment. At one point in time, the simple finding of a concordant disc correlated with desiccation on MRI was enough clinical support to justify the utility of lumbar fusion at one or more levels. In 1990, Walsh et al. published the first standardizations for validating discography that defined pain threshold [5] . Carragee and coworkers’ 1999 paper on false positive findings in lumbar discography began a resurgence on the rebuking of lumbar discography [6] . Skeptics argue against its sensitivity, specificity and positive predictive value. Many believe that modern diagnostics such as MRI make discography obsolete, while others argue the test should be abandoned altogether given its proposed progressive degeneration and disc displacement effects.
future science group
Discography’s role in low back pain management
Review
Does manometry improve reliability?
What wasn’t recognized at the time of either publication was the effect of unpredictable pressurization on the production of pain and the outcome of the test. Derby et al. published the first study illustrating the relationship between the standardization of disc pressure (manometry) and its ability to predict surgical and nonsurgical outcomes [7] . These studies led to the development of the modern interventional practice guidelines for lumbar discography, outlined in Box 1, which include manometry [7] . Failure to adhere to these variables directly impacts on the reliability of the test and has direct implications on the test’s sensitivity and specificity. International Spine Intervention Society
standards
In an attempt to provide more standardized results of lumbar disc stimulation, the International Spine Intervention Society (ISIS) developed a scoring system to aid in its interpretation (Figure 4) . Positive discs are defined by >70 points, discs with scores of 40–60 points are considered indeterminate, while scores below 40 are negative [8] . These benchmarks are designed to minimize borderline or equivocal responses. In order to be accountable to international standards of evidence, uniform discography technique and analysis is strongly encouraged. This includes recording pain at 7/10 and identifying a control disc with a slow injection rate to prevent peak in pressure exceeding 50 psi above opening pressure (AOP) [8] . Injection of contrast at low volume and pressure is unlikely to provoke pain in asymptomatic annular tears [7–10] . Increasing volume and pressure will eventually stimulate nociceptors in asymptomatic discs. This enhances the reliability and validity of the test itself [8] . Of course, the concordant pain should be correlated with discography imaging (Figures 2 & 3) with grade III or greater annular tears. A recent meta-analysis by Wolfer et al. was performed in order to accurately evaluate and portray the false positive rate of lumbar provocative disc stimulation and evaluate its clinical merit [9] . Data from previous publications presents false positive rates of 10% in asymptomatic individuals and 40% in patients with chronic pain without a history of low back pain [6] . In order to apply this data to the general population, CIs can be calculated to evaluate the statistical merit of the data. This demonstrates ranges so broad that drawing meaningful conclusions
future science group
Figure 3. Axial postdiscography CT imaging of lumbar discography on the same patient as in Figure 2. Note that the L5–S1 level was positive for concordant pain.
for standards of care (i.e., disc stimulation contains an unacceptably high false positive rate) is unsupportable. By pooling data, they calculated that the cumulative false positive probability of discography is less than 10% when ISIS standards are utilized. This places the sensitivity within an acceptable range for clinical false positives [9,10] . This meta-analysis further corroborates the accuracy of the ISIS scoring system that was published 4 years prior (Figure 4) . Lowpressure pain provocation (pain at up to 15 psi AOP) as a whole provides a minimal chance of Box 1. International Spine Intervention Society–International Association for the Study of Pain Guidelines for the interpretation of a positive disc. Pain ≥7/10 Concordant pain Grade III/V annular tear Concordant pain produced
Discography’s role in low back pain management
Practice Points
Ryan S Reeves1 & Michael B Furman* Lumbar provocation discography is an ideal clinical test to evaluate and confirm whether or not a
patient’s discs are a source of their axial (nonradicular) pain. Lumbar provocation discography interpretation should include a description of pain response
concordance, manometric pressure data and imaging correlation with fluoroscopic nucleograms and postdiscography computed tomography. Lumbar provocation discography results must be interpreted within the context of a patient’s clinical
scenario and should be utilized after other conservative measures have failed to produce functional benefits. Lumbar provocation discography should be utilized to confirm and circumscribe the lumbar disc as the
axial (nonradicular) pain source before treating with percutaneous or open surgical procedures and/or inclusion in ongoing research protocols. When lumbar provocation discography results are negative, multilevel or unclear for defining the axial
(nonradicular) pain source, percutaneous or open surgical procedures, or inclusion in ongoing research protocols should not be considered.
SUMMARY
Lumbar provocation discography is a commonly used diagnostic procedure utilized to determine the presence or absence of discogenic pain at a specific spinal segment. Although multidisciplinary societies have recognized discography as the primary criterion for identifying discogenic pain, the test remains controversial. Skeptics argue against its sensitivity and specificity, and suggest that it’s risks outweigh any potential benefits. However, when properly performed and interpreted, discography is an invaluable tool. Together with a patient’s history, physical examination and radiological studies, discography will safely identify both symptomatic and asymptomatic discs to provide confirmatory evidence that a particular disc is the source of the patient’s pain. Since information from this study may be used to plan for percutaneous or open surgical procedures, accurate and precise interpretation of the results is vital. Chronic axial low back pain, defined as pain limited to the back without nerve root involvement, is often functionally limiting. For those patients
with chronic axial low back pain who have failed conservative care, it is appropriate to determine whether there is a structural, treatable cause for
Spine Team Texas, Southlake, TX, USA *Author for correspondence: Orthopaedic & Spine Specialists, York, PA, USA; [email protected] 1
10.2217/PMT.11.87 © 2012 Future Medicine Ltd
Pain Manage. (2012) 2(2), 151–157
part of
ISSN 1758-1869
151
Review Reeves & Furman
Figure 1. T2-weighted MRI demonstrating disc dessication and increased signal intensity in the posterior anulus at L5–S1, suggesting that this disc could be a potential pain source.
their pain. Potential sources of chronic axial low back pain include the lumbar discs, zygapophyseal joints, sacroiliac joints and vertebral body compression fractures, amongst others [1] . These should be ruled out as appropriate [2,3] . When
diagnostic tests rule out facet or sacroiliac disease, and history, exam and imaging suggest that one or more lumbar discs are the potential pain generator, discography is clinically warranted, especially after diagnostic tests and procedures have ruled out facet or sacroiliac pathology. This article addresses discography use to assess axial low back pain. For ‘back’ pain which involves a significant component of appendicular or radicular pain into the lower limbs, other diagnostic tools should be considered and are beyond this article’s scope. Discography is usually performed in patients who are considering more invasive treatments such as percutaneous intradiscal or open discal procedures. The procedure is used to identify concordantly painful disc(s) and to verify that adjacent discs are negative for concordant pain prior to a therapeutic interventional procedure or surgery. This provocative test mimics physiologic loads, evoking pain by stimulating nociceptors or pathological innervated annular rents [4] . Pre-procedural diagnostics (Figure 1) , concordant pain provocation during disk pressurization, along with intra- and post-procedural imaging (Figures 2 & 3) , are all used to confirm or refute one’s clinical impression that a specific disc is a pain source. Those with equivocal results or with three or more positive discs are not candidates for further aggressive treatments. Discography controversies False positives or true positives?
Figure 2. Lateral fluoroscopic image of lumbar discography at two levels. Note that the L5–S1 level was positive for concordant pain.
152
Pain Manage. (2012) 2(2)
There is much controversy regarding the utilization of lumbar discography. Lumbar provocation discography has been a commonly used diagnostic procedure utilized to determine the presence or absence of discogenic pain at a specific spinal segment. At one point in time, the simple finding of a concordant disc correlated with desiccation on MRI was enough clinical support to justify the utility of lumbar fusion at one or more levels. In 1990, Walsh et al. published the first standardizations for validating discography that defined pain threshold [5] . Carragee and coworkers’ 1999 paper on false positive findings in lumbar discography began a resurgence on the rebuking of lumbar discography [6] . Skeptics argue against its sensitivity, specificity and positive predictive value. Many believe that modern diagnostics such as MRI make discography obsolete, while others argue the test should be abandoned altogether given its proposed progressive degeneration and disc displacement effects.
future science group
Discography’s role in low back pain management
Review
Does manometry improve reliability?
What wasn’t recognized at the time of either publication was the effect of unpredictable pressurization on the production of pain and the outcome of the test. Derby et al. published the first study illustrating the relationship between the standardization of disc pressure (manometry) and its ability to predict surgical and nonsurgical outcomes [7] . These studies led to the development of the modern interventional practice guidelines for lumbar discography, outlined in Box 1, which include manometry [7] . Failure to adhere to these variables directly impacts on the reliability of the test and has direct implications on the test’s sensitivity and specificity. International Spine Intervention Society
standards
In an attempt to provide more standardized results of lumbar disc stimulation, the International Spine Intervention Society (ISIS) developed a scoring system to aid in its interpretation (Figure 4) . Positive discs are defined by >70 points, discs with scores of 40–60 points are considered indeterminate, while scores below 40 are negative [8] . These benchmarks are designed to minimize borderline or equivocal responses. In order to be accountable to international standards of evidence, uniform discography technique and analysis is strongly encouraged. This includes recording pain at 7/10 and identifying a control disc with a slow injection rate to prevent peak in pressure exceeding 50 psi above opening pressure (AOP) [8] . Injection of contrast at low volume and pressure is unlikely to provoke pain in asymptomatic annular tears [7–10] . Increasing volume and pressure will eventually stimulate nociceptors in asymptomatic discs. This enhances the reliability and validity of the test itself [8] . Of course, the concordant pain should be correlated with discography imaging (Figures 2 & 3) with grade III or greater annular tears. A recent meta-analysis by Wolfer et al. was performed in order to accurately evaluate and portray the false positive rate of lumbar provocative disc stimulation and evaluate its clinical merit [9] . Data from previous publications presents false positive rates of 10% in asymptomatic individuals and 40% in patients with chronic pain without a history of low back pain [6] . In order to apply this data to the general population, CIs can be calculated to evaluate the statistical merit of the data. This demonstrates ranges so broad that drawing meaningful conclusions
future science group
Figure 3. Axial postdiscography CT imaging of lumbar discography on the same patient as in Figure 2. Note that the L5–S1 level was positive for concordant pain.
for standards of care (i.e., disc stimulation contains an unacceptably high false positive rate) is unsupportable. By pooling data, they calculated that the cumulative false positive probability of discography is less than 10% when ISIS standards are utilized. This places the sensitivity within an acceptable range for clinical false positives [9,10] . This meta-analysis further corroborates the accuracy of the ISIS scoring system that was published 4 years prior (Figure 4) . Lowpressure pain provocation (pain at up to 15 psi AOP) as a whole provides a minimal chance of Box 1. International Spine Intervention Society–International Association for the Study of Pain Guidelines for the interpretation of a positive disc. Pain ≥7/10 Concordant pain Grade III/V annular tear Concordant pain produced
