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

January 2008AADEP San Antonio

Discography and the Evaluation of LBP

Eugene J Carragee, MDStanford University

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”

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 15 -25%)

• 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

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

Imaging Findings

• If MRI, CT and Bone Scan are not specific for LBP illness

• Then, how do we finds the “pain generator”

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”?

Discography GoalDiscography 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]

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

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/S1 -- 1998• 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)

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.

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)

Hypothetical Response to Pressurization of a Degenerative

Disc Depending on “Pain Sensitivity”

“Normal”

Increasing Injection Pressure ---->

Pain

HypersensitiveChronic Pain SyndromePsychological Distress2° Gain IssuesNarcotic Habituation

ReducedSocial ImperativesPsychological ReserveCultural Norms

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?

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.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Walsh (-DDD) Pain Free + DDD ISIS study Chronic Pain Somatization

Pain Intensity with Disc Injection in Asymptomatic Subjects

> 8/10

>6 - 8

> 4 - 6

>2 - 4

> 0 - 2

0

Increasing Risk Factors

0

20

40

60

80

Young MenOlder+DDD SpineSociety

Chronic PainPost-op DiscSomatization

low pressure +

medium pressure +

Subjects w/o LBP Summary

Psychometric testing, chronic pain, litigation/contested and anular disruption strongly predict painful injections.

Increasing Risk Factors

Hypothetical Response to Pressurization of a Degenerative

Disc Depending on “Pain Sensitivity”

“Normal”

Increasing Injection Pressure ---->

Pain

HypersensitiveChronic Pain SyndromePsychological Distress2° Gain IssuesNarcotic Habituation

ReducedSocial ImperativesPsychological ReserveCultural Norms

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?

Not Really… look at 3 groups with serious sx for 6 - 18

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)

VAS (mean)

5

5.5

6

6.5

7

Disc Spondy PVO

Oswestry Scores

0

10

20

30

40

50

Disc Spondy PVO

Discogenic pain / PVO significantly worse than Spondy (0.01)

Psychometric Scores

0

5

10

15

20

25

Disc Spondy PVO ASX

MSPQ ZungDisc pain most abnormalP = 0.0001

DRAM Catagories in Studies Groups and Controls

0%

20%

40%

60%

80%

100%

Discogram + Spondyl PVO Soldiers/CLBP Asx Control

Normal At Risk DD/DS

21% nl

75-85% nl

Chronic LBP Patients with Non-specific findings =

“Discogenic Pain”*

0

10

20

30

40

50

60

70

80

90

100

Discogenic Pain

Abnormal Psych

Narcotic dependency

History ofDrug/Alcohol

Compensationlitigation

Other Chronic Painsyndrome

• Cairns et al 2003; Carragee et al 2001; Schwarzer 1995/96

Profiles in Other Spine Pts with Severe Chronic Pain

0

10

20

30

40

50

60

70

80

90

100

Discogenic RA VertOsteo

Spondy AdultScoli

Abnormal Psych

Narcotic dependency

History of Drug/Alcohol

Compensation litigation

Other Chronic Pain syndrome

Which one is not like the other?

*

* - non RA pain

Compare Other Chronic Pain without Clear Local

Pathology

0

10

20

30

40

50

60

70

80

90

100

FibromyalgiaDiscogenic TMJ/Facial Chronic Fat.

Abnormal Psych

Narcotic dependency

History of Drug/Alcohol

Compensation litigation

Other Chronic Pain syndrome

Coincidence ?

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

Concordancy Test Model

0

2

4

6

8

10

No Pain Dissimilar Similar Exact

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

Schematic Approach to Back Pain

Perception and Discography

MuscularFacetBone

L3/4 Disc

L4/5 Disc

L5/S1 Disc

SimilarSclerotom

alAfferents

Perception

DRG

Cord

Thalamus

Cerebral

VisceralVascular

Pelvic

Concordancy and The LBP Pathway

Pathway Modulation1 Adjacent tissue injury2 Local AnaestheticLocal Anaesthetic3 Nearby tissue injury4 Regional Chronic Pain5 Narcotic AnalgesiaNarcotic Analgesia6 Narcotic Habituation7 Depression8 Social ImperitivesSocial Imperitives9 Social Disincentives

1

2

3

4

5 6

78 9

MuscularFacetBone

L3/4 Disc

L4/5 Disc

L5/S1 Disc

SimilarSclerotom

alAfferents

That’s my Pain!!!!

DRG

Cord

Thalamus

Cerebral

Visceral Pelvic

Best Case ScenarioOne pain source

And if you fix it, I’ll feel all better!

Muscular L3/4 Disc

L4/5 Disc

L5/S1 Disc

SimilarSclerotom

alAfferents

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...

FacetBoneMuscular

L3/4 Disc

L4/5 Disc

L5/S1 Disc

SimilarSclerotom

alAfferents

That’s my Pain!!!!

DRG

Cord

Thalamus

Cerebral

VisceralVascular

Pelvic

1° Non-discogenic pain source, minor disc pain

HyperalgesicPain Pathway

And if you fuse it I’ll be about the same...

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.

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?

FacetBoneMuscular

L3/4 Disc

L4/5 Disc

L5/S1 Disc

SimilarSclerotom

alAfferents

That’s my Pain!!!!

DRG

Cord

Thalamus

Cerebral

VisceralVascular

Pelvic

Multiply Operated Back

HyperalgesicPain Pathway

DepressionSomatization

And if you fuse another level, I’ll be as miserable as ever...

FacetBoneMuscular

L3/4 Disc

L4/5 Disc

L5/S1 Disc

SimilarSclerotom

alAfferents

That’s my Pain!!!!

DRG

Cord

Thalamus

Cerebral

VisceralVascular

Pelvic

1° Psychological pain source, common backache

HyperalgesicPain Pathway

DepressionSomatization“fibromyalgia”

“And if you fuse it, you should think of moving your practice…”

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…”

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…”

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...

Do people with common backache have painful disc

injections?• Phase 2 discography protocol...• 25 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

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?

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.

0

10

20

30

40

50

60

70

Negative Positive 2 or more + discs

FacetBoneMuscular

L3/4 Disc

L4/5 Disc

L5/S1 Disc

SimilarSclerotom

alAfferents

That’s my Pain!!!!

DRG

Cord

Thalamus

Cerebral

VisceralVascular

Pelvic

Common backache

Normal “amplified”Pain Pathway And so

what…its not a problem?

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

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?

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”.

FacetBoneMuscular

L3/4 Disc

L4/5 Disc

L5/S1 Disc

SimilarSclerotom

alAfferents

That’s my Pain!!!!

DRG

Cord

Thalamus

Cerebral

VisceralVascular

Pelvic

Secondary Gain (litigation) + pre-existing backache

HyperalgesicPain Pathway

“And it neverfelt like this before that the postal truck hit my car at 3 mph”

Acid TestDoes 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.

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 -- 360° fusion– No Comorbidites--

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…

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.

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.

Results

0

20

40

60

80

100

Cured Some relief

Spondy disco +

False + = 40%

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 (30 - 80%)

– 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…

Practical Usage Guide for Discography in 2008

• Best case1. 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 social2. Post-operative discs, nl psych, nl social3. Intermediate (At Risk) psychometrics, single level.

• Poor Utility1. Spine with multilevel pathology2. Abnormal pain behavior or mutliple chronic pain

processes, 3. Abnormal psychometric findings4. Disputed compensation cases5. As a forensic tool to establish “injury”

Thank you