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January 2008 AADEP San Antonio Discography and the Evaluation of LBP Eugene J Carragee, MD Stanford University.

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Presentation on theme: "January 2008 AADEP San Antonio Discography and the Evaluation of LBP Eugene J Carragee, MD Stanford University."— Presentation transcript:

1 January 2008 AADEP San Antonio Discography and the Evaluation of LBP Eugene J Carragee, MD Stanford University

2 LBP Evaluation in Context Primary Diagnostic Evaluation(<50% ?) –LBP short duration (days - weeks) –Hx, PE, “rule out “red flags” of serious pathology Secondary Diagnostic Evaluation (<5%) –LBP not improving (weeks to1-2 months) –Add ESR, CRP, MRI, motion study X-Rays –Rule out “Yellow Flags”, psychosocial/neurophysiologic factors that inhibit recovery OR coping. Teritiary Diagnostic Evaluation (<1%) –Persistent pain, considering specific rx (months to 1 year) –Only common degenerative findings on imaging so far –Consider discography to identify disc as “pain generator”

3 Common MRI Findings and Pain DDD –Poor correlation with sx (Jensen, Boden) Anular Disruption and HIZ –Poor PPV or NPV (Jensen, Boden, Carragee, etc) –Relative > in CLBP vs Asx (50% vs %) Disc Protrusion and Stenosis –Extrusion (large) rarely seen in Asx (< 5%) –SS neural compression less common in Asx (15%) –Sx -> radicular; not a good LBP predictor Endplate Changes -- latest flavor

4 Common MRI Findings and Pain Modic I - II changes (mod - sev) –10% Asx subjects (Weishaupt Rad 98) –100% PPV at disocgraphy in sx (Weishaupt Radiology 2000) Prediction of future LBP –Best but very modest correlation of future LBP Boos Spine (2000) Carragee Spine J (2004) –Much worse than: DRAM, FABQ, Work Comp, Chronic Pain, Smoking

5 Imaging Findings If MRI, CT and Bone Scan are not specific for LBP illness Then, how do we finds the “pain generator”

6 But first - Defining a Clinically Relevant Pain Generator The “Pain Generator” in LBP illness –as an isolated local pathoanatomic structure Not a physiologic process or psychogenic complaint –independent of co-morbid factors (chronic pain states, depression, somatic distress, litigation, secondary gain, etc) –Reasonable accounts for the chronic LBP illness of the patient When do “Positive” disc injections identify the true “pain generator”?

7 Discography Goal To be a reliable, objective test that can identify a disc as the primary pathology in patients suffering from significant LBP illness. How reliably does discography “identify the pathological feature causing Low Back Pain Illness?” -- [specificity] Or “rule out” a disc as a significant pain source? -- [Sensitivity]

8 The Good Discogram of San Francisco 54 yo master chef. 3 years severe LBP, radiates to gluteals only. No medical problems (really!). Barely able to work. VAS 7-9, Oswestry 45, Daily NSAIDS, occ narcs. Psychometric: normal psychometrics, pain drawing. No WC, litigation, high prestige job, stable marriage X-Ray, collapse and retrolisth L5/S1 MRI: nl L2/3, DDD L3/4, L4/5

9 The Good Discogram of San Francisco In this case…discography, may be key to treatment--> –Nl L2/3 –Anular Disruption L3/4, L4/5 No pain to 50 p.s.i., mild pain at 100. –L5/S1 not injected. ALIF L5/S Returned to work, 2 months p-op, full duty 4 months p-op. (regular 50# lift/carry) 2 yr f/u VAS 0-2, Oswestry 5, occ NSAIDS 5 yr f/u VAS 1-3, Oswestry 8, no meds Some further DDD at L4/5 (now 59 yo)

10 Reliability of Pain Reporting in Discography Note in this Case #1: 1.No concurrent or history of other chronic pain processes. 2.No litigation, WC or secondary gain issues. 3.Normal psychometric, no “reactive depression, anxiety, somatic distress…” 4.Ablation of the suspected “Pain Generator” give high-quality outcome which lasts.

11 Factors Affecting Reported Pain on Disc Injections Disc –Anular Disruption –Pressure Applied Local Pain Sensitivity –Regional chronic pain, previous injury/surgery Generalized Pain Sensitivity –Narcotics, Central Pain Syndromes, –Incentives (Financial, Social) –Disincentives (Financial Social)

12 Hypothetical Response to Pressurization of a Degenerative Disc Depending on “Pain Sensitivity” “Normal” Increasing Injection Pressure ----> Pain Hypersensitive Chronic Pain Syndrome Psychological Distress 2° Gain Issues Narcotic Habituation Reduced Social Imperatives Psychological Reserve Cultural Norms

13 Evidence for Validity and Usefulness of Discography Sackett and Hayes (Br. Med J: 324) Evidence -base criteria for Evaluation of Diagnostic Tests Four Phases - 1. Dx test results in completely normals / no sx / no co-morbidities. 2. Dx test results in subjects w/o the disease BUT w/ sx of disease 3. Dx test applied in subjects w/o the disease BUT epidemiologically likely to have disease (i.e. co- morbidies of the disease) 4. Does having the test result improve outcomes What is the evidence in discography?

14 Studies of Subjects w/o LBP Classic Study - Walsh et al 1990 Healthy young men, little DDD, no chronic pain states, nl psych (Phase 1) Derby, Chen, et al (2003), ISIS: Middle-age, nl psych, highly motivated (Spinal Injection Society Members) (Phase 1, 2) Stanford Group: (2000) (Phase 1 -> 3) Middle-aged, +DDD, no chronic pain, 80% nl psych. Middle-aged, +DDD, chronic pain, 40% nl psych Middle-aged, +DDD, chronic pain, + somatization.

15 Increasing Risk Factors

16 Subjects w/o LBP Summary Psychometric testing, chronic pain, litigation/contested and anular disruption strongly predict painful injections. Increasing Risk Factors

17 Hypothetical Response to Pressurization of a Degenerative Disc Depending on “Pain Sensitivity” “Normal” Increasing Injection Pressure ----> Pain Hypersensitive Chronic Pain Syndrome Psychological Distress 2° Gain Issues Narcotic Habituation Reduced Social Imperatives Psychological Reserve Cultural Norms

18 Do discography pts often have “Risk Factors”? Abn Psych Testing 80% Discography + (Stanford) 79% Discography + (Derby) 80% DDD fusions (Fritzell) Compensation Issues 76% (Schwarzer) 75% (Derby) 68% (Carragee) Chronic Pain 100% -- by definition CLBP 70% -- other chronic pain issues (IBS, TMJ, Migraine…) But don’t all chronic BP patients develop abnormal pain behavior, abnormal psych profiles etc?

19 Not Really… look at 3 groups with serious sx for months Discogenic pain –Positive discography (1-3 levels) –no other pathology known –Carragee et al (Spine 1999, 2000) Isthmic spondylolisthesis –CLBP + Sciatica –Scheduled for single level fusion –Carragee (JBJB 1997) Pyogenic Vertebral Osteomyeolitis –Delayed diagnosis –Dx unknown at time of data collection –Carragee (JBJS 1997)

20 VAS (mean)

21 Oswestry Scores Discogenic pain / PVO significantly worse than Spondy (0.01)

22 Psychometric Scores Disc pain most abnormal P =

23 21% nl 75-85% nl

24 Chronic LBP Patients with Non-specific findings = “Discogenic Pain”* Cairns et al 2003; Carragee et al 2001; Schwarzer 1995/96

25 Profiles in Other Spine Pts with Severe Chronic Pain Which one is not like the other? * * - non RA pain

26 Compare Other Chronic Pain without Clear Local Pathology Coincidence ?

27 How reliable is “Concordancy” Experimental LBP Model (Phase 3) Subjects scheduled for posterior ICBG –for non-lumbar problems (fracture non-union, tumor) Screened for LBP before ICBG –No current of life-time hx of LBP –LBP hx screening 3 x before study All with normal psychometric testing Discography done after ICGB –pain concordancy rated at discography to ICBG pain –Will disc stimulation pain reproduce ICBG pain Completing Study - 8 pts / 24 disc injections »Carragee et al Spine 1999

28 Concordancy Test Model 60% painful discs felt similar to / or exactly like ICBG pain. 50% subjects had + concordant discogram by all criteria. 25% subj. had at least 1 low pressure sensitive disc.

29 Schematic Approach to Back Pain Perception and Discography

30 Muscular Facet Bone L3/4 Disc L4/5 Disc L5/S1 Disc Similar Sclerotomal Afferents Perception DRG Cord Thalamus Cerebral Visceral Vascular Pelvic Concordancy and The LBP Pathway Pathway Modulation 1 Adjacent tissue injury Local Anaesthetic 2 Local Anaesthetic 3 Nearby tissue injury 4 Regional Chronic Pain Narcotic Analgesia 5 Narcotic Analgesia 6 Narcotic Habituation 7 Depression Social Imperitives 8 Social Imperitives 9 Social Disincentives

31 Muscular Facet Bone L3/4 Disc L4/5 Disc L5/S1 Disc Similar Sclerotomal Afferents That’s my Pain!!!! DRG Cord Thalamus Cerebral Visceral Pelvic Best Case Scenario One pain source And if you fix it, I’ll feel all better!

32 Muscular L3/4 Disc L4/5 Disc L5/S1 Disc Similar Sclerotomal Afferents That’s my Pain! ! ! DRG Cord Thalamus Cerebral Visceral Pelvic Two equal pain sources And if you fuse it I’ll be a somewhat better...

33 Facet Bone Muscular L3/4 Disc L4/5 Disc L5/S1 Disc Similar Sclerotomal Afferents That’s my Pain!!!! DRG Cord Thalamus Cerebral Visceral Vascular Pelvic 1° Non-discogenic pain source, minor disc pain Hyperalgesic Pain Pathway And if you fuse it I’ll be about the same...

34 Case 2 35 yo man, severe LBP x 7 mo. Unable to work x 3 month. VAS 9-10, Oswestry 50, Psych “At risk” Meds Daily Narcotics X-ray nl, MRI DDD + HIZ L5/S1 Discogram: 10/10 concordant pain L5/S1 Nl L4/5, L3/4, but CT sclerosis L4 pedicle.

35 Case 2 Bone Spec Scan, hot at L4 Excisional biopsy, “osteiod osteoma” Fusion L3-4, unilateral pedicle screws. RTW, 2 month post-op 3 year f/u –VAS 1-2, Oswestry 10, occ. NSAID –Stanford Score 8.8 (0-10) Why did the L5/S1 disc have a severe concordant pain with injection?

36 Facet Bone Muscular L3/4 Disc L4/5 Disc L5/S1 Disc Similar Sclerotomal Afferents That’s my Pain!!!! DRG Cord Thalamus Cerebral Visceral Vascular Pelvic Multiply Operated Back Hyperalgesic Pain Pathway Depression Somatization And if you fuse another level, I’ll be as miserable as ever...

37 Facet Bone Muscular L3/4 Disc L4/5 Disc L5/S1 Disc Similar Sclerotomal Afferents That’s my Pain!!!! DRG Cord Thalamus Cerebral Visceral Vascular Pelvic 1° Psychological pain source, common backache Hyperalgesic Pain Pathway Depression Somatization “fibromyalgia” “And if you fuse it, you should think of moving your practice…”

38 Case 3 49 yo woman, severe LBP, no WC BUT... Disabled for years, conserv. Rx makes worse. Injections give transient relief. Also CTS, migraines, pelvic pain, palpitations, irritable bowel syndrome. CTR, appy, chole (no help) in past In ER 1 week PTA “unable to move legs”. Sister says: “ She has a very high pain threshold…”

39 Case 3 Work up shows collapsing weakness and DDD in spine, MRI no tumor, infection, cord compression. Returns 6 weeks later with outside w/u: –Discography L4/5 and L5/S1 10/10 concordant and fissured, low pressure. –L3/4 mild DDD 2/10 discordant pain –Psych interview feels emotiomal sx due to chronic pain. A surgeon recommends fusion based on the “objective findings on discography…”

40 Case 3-- ”She’s Back” Returns 2 years later had surgery L4-S1 solid 360° fusion Still terrible pain but feels surgery “helped” for a few months…(would do it again). Recent Discogram shows 10/10 L3/4 pain. Negative L2/3 “control” Another surgeon now recommends to fuse L3/4 based on positive discogram. How did we get into this mess...

41 Do people with common backache have painful disc injections? Phase 2 discography protocol volunteers with persistent LBP –> 2 year, OSW < 15 –No work loss, No activity restriction –No meds, not seeking medical rx. –Nl psych –MRI Signal loss in at least 1 lumbar disc That is: People with “common backache.” –Carragee et al, The Spine Journal, 2002

42 Common Backache Study Protocol Full Walsh protocol for experimental discography. Question: –What kind of pain response? –Will it be concordant if present? –Can we differential using discography CLBP patients from Common Backache?

43 Bachache and Discography 36% “Backache group” had “bad” concordant pain Most are low pressure sensitive discs It is possible discography cannot tell common clinically-irrelevent BP from CLBP illness.

44 Facet Bone Muscular L3/4 Disc L4/5 Disc L5/S1 Disc Similar Sclerotomal Afferents That’s my Pain!!!! DRG Cord Thalamus Cerebral Visceral Vascular Pelvic Common backache Normal “amplified” Pain Pathway And so what…its not a problem?

45 Or is it a problem…Case 4 48 yo man, long hx LBP, occ. treatment MVA 1997, pt claims “different LBP” since accident and totally disabled. Seen after work-up, referred for discography. MRI shows DDD, L4/5, L5/1 HIZ at L4/5

46 Working the system…Case 4 Diffuse pain. Bizarre pain drawing. OSW = 62; VAS (mn) = 8; Daily Narc. DRAM - Distressed Despressed Pre-existing “Anxiety Disorder” Will discography clear up this picture?

47 Working the System Seen 8 months later at request of his attorney. Discography done in community: L3/4 minor fissuring; 8/10 concord. L4/5 and L5/S1 anular tear; 10/10 concord. L2/3 “neg control disc” Report reads “3 level symptomatic anular tears …caused by recent accident since [injection] only reproduces new pain since accident…causation in legal action clearly determined by discographic findings ”.

48 Facet Bone Muscular L3/4 Disc L4/5 Disc L5/S1 Disc Similar Sclerotomal Afferents That’s my Pain!!!! DRG Cord Thalamus Cerebral Visceral Vascular Pelvic Secondary Gain (litigation) + pre-existing backache Hyperalgesic Pain Pathway “And it never felt like this before that the postal truck hit my car at 3 mph”

49 Acid Test Does discography improve outcomes Mixed –Comparing fusion surgerys in different studies w/ and w/o discography –No differences (Cohen, et al 2003) British retrospective study with very different patient groups (Calhoun) –Modestly improved outcomes in discography group. New York Group(2003 J Spinal Dis) –Prospective –Historical control –No difference in discography group: using discography did not improve outcomes in this controlled study.

50 Outcome as Gold Standard Usually Outcome is considered poor diagnostic gold standard: –Failure related to patient selection –Failure related to operative morbidity Controlled “Pain Generator” Study –Single Level “Discography +” group versus –An ideal single segment “Pain Generator” Unstable spondylolisthesis (>4 mm / >11°) –Do identical operation ° fusion –No Comorbidites--

51 Outcome as Gold Standard Exclusions: –> 18 months of current episode –Not working prior to latest episode –Abnormal DRAM –More than 1 abnormal segment (adjacent segments are NORMAL discogram) –No work comp / no litigation –No other chronic pain history No alibi’s! Best case scenario…

52 Hypothesis IF -- both groups are correctly diagnosing a single segment pain generator AND -- both have equal patient selections and surgical risks/morbidity THEN -- the surgical outcomes should be the same. IF NOT -- the difference will = false positive rate.

53 Subjects 30 “discography +” DDD –5 years to recruit 32 unstable spondylolisthesis –Same time period No significant difference in baseline –VAS, ODI, work loss, smoking, DRAM, FABQ, sx duration, medication use.

54 Results False + = 40%

55 Summary –Phase 1 studies were encouraging with low risk of false positive in completely normal subjects. –Phase 2 and 3 studies show higher risk with increasing co-morbidities associated with CLBP illness ( %) –Phase 4 studies are inconclusive or non-supportive for discography validity at this point. –Still not answer to distinguishing severely painful from common DDD in spine…

56 Practical Usage Guide for Discography in 2008 Best case 1. Negative discogram (next to other pathology - spondy etc) 2. Positive, single level, nl psych, nl social (WC, Lit) - 50% PPV Unclear Utility 1. 2 level Positive, nl psych, nl social 2. Post-operative discs, nl psych, nl social 3. Intermediate (At Risk) psychometrics, single level. Poor Utility 1. Spine with multilevel pathology 2. Abnormal pain behavior or mutliple chronic pain processes, 3. Abnormal psychometric findings 4. Disputed compensation cases 5. As a forensic tool to establish “injury”

57 Thank you


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