Summary
Chronic low back pain (LBP) can be ‘progressive onset' or injury-related. This study compares the patient-reported cause of chronic LBP to features of disc internal derangement at painful concordant discs evaluated by provocation lumbar discography.
Concordant LBP was identified in 114 patients with chronic LBP studied by provocation discography. LBP cause, discogram pain response and discogram/post-discogram CT features of internal derangement were retrospectively reviewed.
‘Progressive-onset' LBP was reported in 32 (28%) patients, injury-related LBP in 75 (66%) with LBP equated to non-specific causes in seven.
Injury-related LBP was more commonly identified in men (52 of 63 [83%]) with women reporting near-equal frequency of ‘progressive-onset' (23 of 44 [52%]) and injury-related (21 of 44 [48%]) LBP (p=0.002).
In 172 concordant painful discs, near-equal frequency of severely degenerative (Dallas grade-3: 82 of 172 [47.3%]) and full-thickness radial fissure discs (Dallas grade-3: 90 of 172 [52.7%]) were identified.
Women with ‘progressive-onset' LBP demonstrated more frequent severely degenerative discs (24 of 37 [65%]); women with injury-related LBP demonstrated more frequent radial-defect discs (21 of 31 [68%]; p=0.01).
In men with injury-related LBP, severe degeneration-only (44 of 89 [49%]) and radial defect discs (45 of 89 [51%] were seen with equal frequency. In men with ‘progressive-onset' LBP, radial defects are more common (11 of 15 [73%]).
‘Progressive-onset' and injury-related chronic LBP subgroups are definable. Gender-related differences in incidence and internal derangement features at concordant discs are identified at discogram/post-discogram CT. These differences may have implications related to LBP origin/treatment-response.
Key words: lumbar spine, low back pain, discography, computed tomography, progressive disc degeneration
Introduction
Low back pain (LBP) is a common condition with an annual prevalence ranging from 15-45% and a lifetime prevalence of 60-80% 1-3. Structures associated with LBP include the facet joint, sacroiliac joint, inter-vertebral disc and muscles in spasm. Most acute-onset LBP recovers within 12 weeks but approximately 5% of patients develop chronic symptoms 4. Risk factors and clinical differences associated with chronic low back pain include: increasing age, gender, genetic predisposition, litigation, work characteristics, along with socioeconomic, psychological and lifestyle-related factors.
The intervertebral disc is a recognized anatomic structure associated with LBP but confirming discogenic origin of LBP is difficult. Discography, while controversial, remains the only physical examination tool that can actively challenge the disc (provocation) and relate the patient sensation, including concordant LBP if reproduced, with the morphologic features of the disc noted at imaging 5. Discography results can also have important clinical and treatment implications 6.
While patients with chronic LBP commonly relate the onset of their symptoms to a specific injury, Smedley et al recognizes a distinct subset of new-onset LBP patients that clearly describe gradual onset of symptoms without a specific inciting event 7. Most studies evaluating discography focus on the longstanding chronic duration of LBP when describing their patient cohort inclusion criteria. In one study comparing discography with myelography, Grubb et al. 8 notes that approximately one third of their patients had insidious onset of pain without distinct incident, similar to the observations of Smedley 7.
The purpose of this study is to compare the patient-reported ‘precipitating events' or ‘causes' of chronic LBP to the imaging features of disc internal derangement identified on post-discogram computed tomography (CT) at concordant painful disc levels in patients referred for provocation lumbar discography.
Materials and Methods
Over a 24-month period, provocation lumbar discography was performed in 150 patients who were referred for symptoms of chronic LBP without or with concomitant leg pain. Patients were referred by spine focused Orthopedic Surgeons or Neurosurgeons in evaluation for potential lumbar spine surgery. Non-concordant pain only was encountered at disc provocation in 14 patients, eight patients had prior spine fusion and 14 patients had a negative provocation discography study and these patients were therefore ultimately excluded.
Of the 150 patients, 114 had concordant pain provoked at one or more levels during provocation lumber discography. The clinical information, provocation discogram observations and post-discogram CT of these 114 patients with concordant pain involving at least one level were retrospectively reviewed and are the focus of this study. Institutional review board approval was obtained for this retrospective analysis.
The clinical cause of LBP as relayed by the patient was noted along with the discogram pain response at the studied levels. Patients were ultimately categorized into subgroups including 1) chronic LBP related to a specific event/injury, 2) insidious, ‘progressive-onset' of chronic LBP without a clear inciting event or 3) patients who related their chronic LBP to other more non-specific cause (i.e. prior spine surgery). Longstanding athletes with chronic LBP related to their participation in athletic endeavors were categorized in the injury subgroup as these patients typically described multiple painful events related to their sport activities. One patient was studied who experienced sudden severe onset of LBP without insidious progression or an inciting event.
The discogram and post-discogram CT were evaluated for the presence of features of internal derangement (radial defect [full-thickness radial annular fissure, annular gap] versus annular degenerative change) as described by Videman and classified by a modification of the standard Dallas classification system 9-11.
Lumbar discography technique
Discography was performed in a standard fashion after informed consent in all 150 patients. The patient's LBP history was clarified using the 0-10 Visual Analog Scale (VAS) including the most-severe LBP level and the patients immediate pre-procedural pain level. Limited intravenous conscious sedation (fentanyl, 0.05 mg; midazolam [Versed]), 1 mg) was given prior to the procedure with a dose of fentanyl typically administered at the end of the examination. Additional fentanyl was administered during the procedure only on rare occasions when disc provocation resulted in severe patient pain that was not responsive to intra-discal anesthetic. Level-of-consciousness was never affected. Supplemental conscious sedation during the discography was generally avoided. The lower lumbar region was cleansed, draped, and with C-arm fluoroscopy, local anesthetic was applied to the trajectory of the targeted discs (OEC Series 9800; GE Healthcare, Milwaukee, WI, USA). The discs were accessed with double-needle technique (20-gauge guiding spinal needle then a curved long 25-gauge spinal needle) directed into the center of the disc space. All needles were placed concordantly opposite the side of leg pain before individual disc injection. Anticipated normal/control disc level was typically studied first.
Disc spaces were studied under direct fluoroscopy by a moderate-to-rapid hand injection of 1.5- to 4.5-mL iohexol, 240 mg Iodine/mL. Injection volume was dependent on 1) disc-volume end point, 2) clearly established severe pain response, or 3) exaggerated capacity in degenerative discs. Patients were kept unaware of whether a level was being provoked or which level was being studied. Response to injection was observed by the operator, and with a positive pain response, the features of the pain were clarified, VAS level of pain was established, and these items were recorded in a manner similar to the technique of Walsh et al. 12. Concordant pain was recorded if the provoked pain was the patient's typical or familiar pain, and non-concordant pain was recorded if the provoked pain was not the typical pain. Fluoroscopic spot-films were obtained for each disc level in anterior-posterior and lateral projections during and following the injections.
During disc testing, the patient's immediate response to injection, response to injection end point (if present), and perception of provoked pain (concordant or discordant) were the primary focus of the discographer. Syringe-disc pressures were not recorded during injection.
If a significantly painful disc space (typically VAS ≥ 6-7, concordant or non-concordant) was encountered, preservative-free lidocaine (2% strength, 1- to 1.5-mL lidocaine (Xylocaine-MPF) was injected into the disc in an attempt to reduce the patient's provoked pain and to allow response clarity in subsequently studied lumbar levels.
Post-discogram CT and categorization by supplemented Dallas Discogram Scale
Postdiscogram CT (GE Healthcare, Milwaukee, WI) was obtained in all patients immediately following the discogram (bone/soft-tissue algorithms; direct axial 3-mm-section acquisition or spiral technique, 3-mm axial and sagittal reformatting, isotropic voxels).
Assessment of the post-discogram CT features generally followed the characteristics referred to in the modified Dallas discogram scale. Fundamental observations and subdivisions included the following: 1) radial annular defects (full-thickness radial annular fissures, annular gaps) and 2) degenerative disc features only.
Radial annular defects (RDs), including full-thickness radial annular fissures (RAFs; Dallas grade 3 radial annular clefts with opposable edges, 1-8 mm in size) and radial Annular Gaps (AGs; grade 3 radial annular clefts beyond simple expansion of a grade 3 radial tear related to an avulsed or macerated annular fragment), were commonly seen. All of the RDs (AGs and RAFs) were in the substance of the annulus and typically retained a portion of the peripheral annular margin with various thicknesses.
Annular degeneration was graded according to traditional Dallas criteria (grade 1, <10%; grade 2, <50%; grade 3, >50%). Features of advanced degenerative annular change Dallas Grade 3 were typically noted on post-discogram CT including: peripheral circumferential annular fissures; lamellar concentric annular fissures; bucket-handle fissures; attached annular fragments; and free annular fragments/macerated annular debris.
Statistical analysis
Statistical analysis was performed by Chi squared comparison between clinical subtype (progressive-onset, injury) and gender, clinical subtype and disc internal derangement features, gender and disc internal derangement features. SAS software (Version 9.2) was used for all analyses (SAS/STAT User's guide, 2008, SAS Institute, Cary, NC, USA). All statistical tests were two-tailed and statistical significance was set at p < .05.
Results
Of the 150 patients, 114 had concordant pain provoked at one or more levels during provocation lumber discography. Non-concordant pain only was encountered in 14 patients at disc provocation, eight patients had prior spine fusion and 14 patients had a negative provocation discography study and these 36 patients were therefore not further analyzed.
Sixty nine of the 114 patients (60.5%) were male and 45 female (39.5%) with an average age 42 years (range, 15-71 years). A single concordant level was identified in 55 patients (47%) and 59 patients (53%) had two or more concordant levels (two levels-47 patients; three levels-15 patients; four levels-six patients; five levels-one patient).
Insidious, ‘progressive-onset' of chronic LBP without an inciting event was reported in 32 of 114 patients (28%; general progression-29; progression after pregnancy-three) with 75 patients (66%) relating a prior injury as the primary cause (lifting injury-28; motor vehicle accident- 18; fall-nine; longstanding athlete-five; other injury-15).
Four of 114 patients equated their chronic LBP to prior spinal surgery (discectomy), one patient had transient non-reproducible concordant pain, one patient equated their pain to work only and one patient described sudden severe LBP without an inciting event. These seven patients were not analyzed statistically due to non-specific, less clear categorization of their clinical presentation. Final analysis was therefore performed on 107 patients.
The results comparing inciting event related to LBP, gender and imaging features of internal derangement in the 107 patients is summarized in Tables 1-6. In men, 52 of 63 (83%) equated their chronic LBP to a specific injury with ‘progressive-onset' identified in 11 of 63 (17%). In contrast, women noted a near equivalent incidence of ‘progressive-onset' (21 of 44 [48%]) and injury-related (23 of 44 [52%]) low back pain. Injury was therefore more commonly identified as the cause of chronic LBP in men as compared with women (Table 1) and this difference was statistically significant (p=0.002).
Table 1.
Comparison of progressive-onset vs. injury-related subgroups by gender.
| Subgroup | Gender | Total | |
|---|---|---|---|
| Female | Male (%) | ||
| Progressive-onset | 21 (48%) | 11 (17%) | 32 (30%) |
| Injury-related | 23 (52%) | 52 (83%) | 75 (70%) |
| Total | 44 (100%) | 63 (100%) | 107 (100%) |
Table 2.
Overall comparison of disc internal derangement in ‘progressive-onset' vs. injury-related subgroups
| Subgroup | Features of Disc Internal Derangement | Total # Disks (%) |
|
|---|---|---|---|
| Degenerative change only # Discs (%) |
Radial Defect # Discs (%) |
||
| Progressive-onset | 28 (53.8%) | 24 (46.2%) | 52 (100%) |
| Injury-related | 54 (46.4%) | 66 (53.6%) | 120 (100%) |
| Total | 82 (47.7%) | 90 (52.3%) | 172 (100%) |
Table 3.
Comparison of disc internal derangement in women: ‘progressive-onset' vs. injury-related subgroups
| Subgroup | Features of Disc Internal Derangement | Total # Disks (%) |
|
|---|---|---|---|
| Degenerative change only Discs (%) |
Radial Defect # Discs (%) |
||
| Progressive-onset | 24 (65%) | 13 (35%) | 37 (100%) |
| Injury-related | 10 (32%) | 21 (68%) | 31 (100%) |
| Total | 34 (50%) | 34 (50%) | 68 (100% |
Table 4.
Comparison of disc internal derangement in men: ‘progressive-onset' vs. injury-related subgroups
| Subgroup | Features of Disc Internal Derangement | Total # Disks (%) |
|
|---|---|---|---|
| Degenerative change only # Discs (%) |
Radial Defect # Discs (%) |
||
| Progressive-onset | 4 (27%) | 11 (73%) | 15 (100%) |
| Injury-related | 44 (49.5%) | 45 (50.1%) | 89 (100%) |
| Total | 48 (46%) | 56 (54%) | 104 (100%) |
Table 5.
Comparison of disc internal derangement in patients with ‘progressive-onset' low back pain
| Subgroup | Features of Disc Internal Derangement | Total # Disks (%) |
|
|---|---|---|---|
| Degenerative change only Discs (%) |
Radial Defect # Discs (%) |
||
| Progressive-onset (Female) | 24 (65%) | 13 (35%) | 37 (100%) |
| Progressive-onset (Male) | 4 (26%) | 11(74%) | 15 (100%) |
| Total | 28 (54%) | 24 (46%) | 52 (100%) |
Table 6.
Comparison of disc internal derangement in patients with injury-related low back pain
| Subgroup | Features of Disc Internal Derangement | Total # Disks (%) | |
|---|---|---|---|
| Degenerative change only #Discs (%) |
Radial Defect # Discs (%) |
||
| Injury-related (Female) | 10 (32%) | 21 (68%) | 31 (100%) |
| Injury-related (Male) | 44 (49.5%) | 45 (50.1%) |
89 (100%) |
| Total | 54 | 66 | 120 (100%) |
Features of internal derangement
One hundred seventy two (172) painful concordant disc levels in the 107 patients demonstrated features of disc internal derangement and the imaging results are summarized in Table 2. Two additional concordant levels had prior discectomy with 11 additional levels appearing normal at discography and post-discogram CT. The results of these 13 levels were not analyzed further.
Overall, the features of internal derangement were similar in the ‘progressive-onset' and ‘injury-related' subgroups with the ‘progressive-onset' group demonstrating severe Grade 3 degeneration-only slightly more commonly (28 of 52 [53.8%]) than discs with a Grade 3 radial annular defect (24 of 52 [46.2%]) and the ‘injury-related' group demonstrating Grade 3 radial defects slightly more frequently (66 of 120 [53.6%]) than severe degeneration-only discs. These trends were not statistically significant (p=0.37). Diminutive radial fissures in isolation (grades 1–2) were rarely observed.
More detailed analysis by gender is summarized in Tables 3-6. Women with ‘progressive-onset' LBP demonstrated severe degeneration-only in 24 of 37 (65%) painful concordant discs (Table 3; Figures 1A,B and 2) with Grade 3 radial defect identified in only 13 (35%). Women with injury-related pain demonstrated Grade 3 radial defects in 21 of 31 (68%) concordant discs (Table 3; Figures 1C,D and 3) with severe degeneration-only in only 10 of 31 (32%). These differences were statistically significant (p=0.01).
Figure 1.
Two women with LBP and single-level concordance at provocation discography. A,B) Patient is a 52-year-old woman with a 6 year history of progressive LBP. Concordant pain was encountered at L3-L4 with a VAS pain level of 8-9/10. Lateral discogram image (A) demonstrates internal disc derangement at L3-L4 (arrow). Post-discogram CT (B) demonstrates severe Dallas Grade 3 annular degeneration (arrows). C,D) Patient is a 53-year-old woman with severe LBP since a fall on the ice 4 years ago. Concordant LBP was encountered at L5-S1 with a VAS pain level of 8/10. Lateral discogram image (C) demonstrates internal disc derangement at L5-S1 (arrow). Post-discogram CT (D) demonstrates a right sided lateral radial tear (arrow) projecting into a peripheral annular tear (arrowheads).
Figure 2.
A,B) Patient is a 33-year-old woman with a long-standing history of progressive LBP without specific inciting event. Concordant LBP was encountered at L4-L5 (A) and L5-S1 (B) with VAS pain levels of 7/10. A) Lateral discogram image demonstrates disc internal derangement at L4-L5 (short arrow) and L5-S1 (long arrow). B) Post-discogram CT at L4-L5 demonstrates severe annular degeneration/fragmentation (arrows). C) Post-discogram CT at L5-S1 demonstrates severe annular degeneration/fragmentation (arrows).
Figure 3.
Patient is a 33-year-old gymnast with long-standing LBP since her athletic activities. Concordant LBP was encountered at L3-L4 (VAS 10/10), L4-L5 (VAS 8/10) and L5-S1 (VAS 10/10). Post-discogram CT demonstrated radial tears/fissures at all three levels. A) AP discogram image demonstrates disc internal derangement at L3-L4, L4-L5 and L5-S1. B) Post-discogram CT at L3-L4 demonstrates a left-sided Dallas Grade 3 radial tear (arrow) projecting into a peripheral annular tear (arrowhead). C) Post-discogram CT at L4-L5 demonstrates a Dallas Grade 3 left-sided radial tear (arrow) projecting into a focal peripheral annular tear (arrowhead). D) Post-discogram CT at L5-S1 demonstrates bilateral Dallas Grade 3 lateral radial tear (white arrow) with fragmentation of the residual intervening posterior annulus (black arrows) with peripheral annular tears and residual peripheral annular margin (white arrowheads).
By contrast, in men with ‘progressive-onset' LBP, 11 of 15 discs (73%) demonstrated radial defects (Table 4; Figure 4) with 4 of 15 discs (27%) demonstrating severe degeneration-only. Men with injury-related LBP demonstrated near-equal frequency of degenerative-change only and radial defect discs (Table 4; Figures 5-7). While the trend of the presence of radial defects in the men with ‘progressive-onset' LBP was apparent, the overall difference when compared with the injury-related group was not statistically significant (p=0.17), potentially related to small sample size in the progressive group.
Figure 4.
Patient is a 33-year-old man with a 3 year history of progressive LBP. Concordant LBP was encountered at L4-L5 (VAS 10/10). A,B) AP and lateral discogram images demonstrate disc internal derangement at L4-L5 (arrows) with radial tear and contrast leak into the canal. C) Post-discogram CT demonstrates a Dallas Grade 3 central radial tear/fissure (large black arrow) projecting into a peripheral annular tear (white arrowhead) with some degeneration of the adjacent attached residual annular components (small white arrows).
Figure 5.
Patient is a 52-year-old man with a 20 year history of LBP following a lifting/twisting injury with heavy weight. He had severe concordant LBP encountered at L3-L4 and non-concordant pain at L4-L5 and L5-S1. A,B) AP and lateral discogram images demonstrate significant internal disc derangement at L3-L4 (short arrows) and L4-L5 (long arrows). C) Post-discogram CT at L3-L4 demonstrates bilateral Dallas Grade 3 radial tears (white arrows) with fragmentation and lamellar separation of the residual intermediate annulus (black arrows). D) Post-discogram CT at the non-concordant L4-L5 level demonstrates severe Dallas Grade 3 annular degeneration (arrows).
Figure 6.
Patient is a 53-year-old man with severe LBP since a fall 3 years ago. Concordant LBP was encountered at L4-L5 and L5-S1. A,B) AP and lateral discogram images demonstrate severe disc internal derangement at L4-L5 (long arrows) and L5-S1 (short arrows). C) Post-discogram CT at L4-L5 demonstrates severe Dallas Grade 3 annular degeneration (arrows). D) Post-discogram CT at L5-S1 demonstrates severe Dallas Grade 3 annular degeneration (arrows).
Figure 7.
Patient is a 49-year-old man with severe LBP since a lifting injury 5 years ago. Concordant pain was encountered at L4-L5 with mild concordant pain provoked at L5-S1. A,B) AP and lateral discogram images demonstrate internal derangement at L4-L5 (long arrows) and L5-S1 (short arrows). C) Post-discogram CT at L4-L5 demonstrates a lateral tear (white arrow) projecting into a focal protruding peripheral annular tear (black arrowheads). D) Post-discogram CT at L5-S1 demonstrates severe Dallas Grade 3 annular degeneration and fragmentation (arrows).
The features of disc internal derangement in men and women with progressive-onset LBP are presented in Table 5. Women with ‘progressive-onset' pain demonstrated more severe degeneration-only discs (24 of 37 [65%]) than discs with radial defect while men with ‘progressive-onset' LBP demonstrated more radial defects (11 of 15 [74%]) and this was statistically significant (p=0.03).
The features of disc internal derangement in men and women with injury-related onset LBP are presented in Table 6. Men with injury-related LBP demonstrated no significant difference in the features of disc internal derangement while women demonstrated more frequently observed discs with radial defects (21 of 31 [68%]) but this was not statistically significant (p=0.15).
Discussion
Age-related biochemical changes, morphologic changes and degeneration are known to occur in the intervertebral disc and these alterations increase in frequency with advancing age. The inter-vertebral disc progressively loses proteoglycan (aggrecan) content resulting in reduced disc water binding capacity, reduced disc hydration and subsequently disc desiccation 13. In addition, radial and concentric annular fissures develop with age and reduce the ability of the disc to maintain structural integrity and stability 14-16. The consequences of age-related biochemical and degenerative change can be observed in patients.
Clinical, autopsy and imaging studies demonstrate evidence of disc degeneration in children both without and with LBP and its prevalence increases with age into adulthood. In large cohort studies, LBP was found to be low in young children (seven-year-olds: 1%), increase in adolescents (12-year-old: 7%; 14-16-year-old: 18%) reaching 50% in 18-20-year-old young adults 17-19. Degenerative disc changes were identified by MR imaging in 30% of 13-year-old children 20. MR imaging evidence of disc degeneration was present in 26% of control 15-year olds but 38% with LBP 21 and disc degeneration was also lower in asymptomatic 14-year-olds (19%) as compared to 14-year-olds with LBP (42%), increasing in frequency in both groups on follow-up imaging (26% and 58% respectively) 22. Disc degeneration appears more common in elite athletes as compared with control population 23 and symptomatic disc herniation requiring operative treatment is more common in teenagers as compared with younger children in particular in those teenagers with a history of sport-related activity or trauma.
Autopsy studies have confirmed an age-related increase in disc internal derangement. In cadaveric studies by Videman et al, disc internal derangement features parallel our observations at discography with degenerative-change-only discs and discs with radial annular defects identified 11. Imaging evidence of disc degeneration also increases with age on radiographs (osteophytes, disc narrowing) 28. Degenerative disc changes are common on MR imaging studies in young adults being identified in 54% of men and 42% of women 20-22 years of age 29.
Numerous studies have documented evidence of disc degenerative change in asymptomatic as well as symptomatic middle-aged population including common observation of disc bulging, focal disc protrusion, annular fissures and disc extrusion 30-32. Disc degeneration as defined by MR imaging has been found to be equal in frequency when comparing patients with discogenic LBP confirmed by discography with a matched asymptomatic cohort 33.
LBP commonly occurs in the setting of injury or trauma, but a subset of patients is recognized that appears to develop LBP gradually or insidiously without a specific inciting event. Smedley et al evaluated 1366 hospital-based nurses over a two-year period with new-onset LBP was reported in 514 (38%) of subjects 7. Gradual-onset LBP was common, noted in 302 (59%) subjects, and was distinct from sudden-onset LBP (work-related (14%) or spontaneous (28%)) 7. Grubb et al. in their study of chronic LBP patients comparing discography with myelography and routine roentgenograms, notes that insidious onset of LBP was reported in 33% of their patients with the remainder related to accident or work-related incident 8.
Our data parallels the observations of Grubb et al. 8 with gradual-onset LBP specifically reported in 28% of our chronic LBP patients. Absence of an injury history in these patients suggests that progressive age-related changes or degeneration is responsible for their chronic discography positive LBP. This distinct group may represent a unique and important subset of patients with LBP.
In our study population, women report near-equal frequency of ‘progressive-onset' and ‘injury-related' LBP. Men report ‘injury-related' LBP more commonly than ‘progressive-onset' LBP. In spite of this observation, no significant difference was identified between the stated cause of LBP (progressive-onset; injury) and the features of internal derangement in concordant discs in the overall study population.
When further analyzed by gender, several interesting differences were apparent. Women with ‘progressive-onset' LBP demonstrated more degenerative-change-only concordant discs (65%). In contrast, men with ‘progressive-onset' LBP demonstrated more concordant discs with radial defects (74%). Separately, women with ‘progressive-onset' LBP demonstrated more degenerative concordant discs while women with injury demonstrated more common radial defect concordant discs. Men did not demonstrate this effect, with a similar frequency of severe degeneration-only discs and radial-defect discs in ‘progressive-onset' and injury subgroups. This last observation parallels a recent report where non-injured and injured male twins demonstrated a similar incidence of disc degeneration 34.
Several factors could account for these differences. Patients with progressive-onset chronic LBP may represent a subset that have developed advanced forms of age-related disc changes or degeneration during the course of ‘routine life activity' in the absence of a specific injury or incident. These patients with gradual-onset discogenic LBP may represent a unique sub-group with more rapidly advancing disc degeneration due to genetic predisposition or potential secondary effects (i.e. smoking) similar to what is observed in the general population. In addition, while psychological factors might still be present in this cohort, other known secondary issues (litigation, workman's compensation) are not present as confounding factors. The absence of these confounding issues could be important including how this affects the patient cohort's response to LBP treatment.
Gender-related tissue differences might be present leading to simple disc fissuring or fragmentation in women. Tissue strengthening, including disc strengthening, occurs in the setting of moderate disc pressurization and activity simulation 35. Long-standing physical activity such as involvement in sports could lead to several effects. In the absence of distinct injury, long-standing physical activity could cause overall disc strengthening with less common natural fragmentation. Alternatively, sport-related activity could also lead to increased spine and disc stresses resulting in a greater frequency of radial or concentric defects 35. The reason for these differences between men and women is as yet not clear.
Previous studies in patients with lumbar spine pain have also demonstrated gender differences. LBP is more common in women 36-38 and this difference remains an important independent risk factor even after multivariate analysis 36. Freburger et al. in a study of North Carolina households reported a prevalence of chronic LBP in 12.2% of females and 8.0% of males 38. Through epidemiologic surveys of patients in Germany, Chenot et al. showed that women are more commonly and more severely affected by LBP 37. Based on a ten-year cohort study in the Netherlands by van Oostrom et al., new episodes of chronic LBP were relatively frequent and more common in women 39. On radiographs, De Schepper demonstrates greater osteophyte formation in men but more disc height loss in women 28. Disc degeneration was more common in men in both the autopsy study of Miller et al. 27 and MR imaging study of young adults (ages 20-22y) by Tahatalo et al. 29.
Our data suggests that additional clinical and pathologic differences may be present between men and women with chronic discogenic LBP. The reason for this gender difference is not clear. Physical activity or genetic factors could play a role in tissue and disc strength leading to different injury thresholds between men and women. Differences were noted in autopsy studies with less disc abnormality identified in discs of patients who had moderate activity in life and more LBP in patients who were more sedentary 40. Alternatively, pre-existent age-related changes or degeneration might be present leading to an altered injury threshold.
Limitations
Several limitations are present in our study. By its retrospective structure, more detailed information of specific litigation or workman's compensation status of the patients that have experienced injury are not available. In addition, other risk factor data that could be revealing were not systematically recorded including patient smoking habits. These associated clinical issues could be important and shed further light on factors of co-morbidity.
Conclusion
‘Progressive-onset' chronic LBP appears to be a definable subset of patients presenting for lumbar provocation discography. In our patients, ‘progressive-onset' chronic LBP was more commonly reported in women with ‘injury-associated' chronic LBP more commonly reported in men.
In the overall population, there was no significant difference in the features of disc internal derangement in concordant painful discs. Severe degeneration-only discs were found as often as discs with Grade 3 radial defects in the progressive-onset and injury-related subgroups. Gender differences however were present.
Women with ‘progressive-onset' of symptoms more often demonstrate degenerative disc changes while those with prior injury more often demonstrate radial defects. In men, no definite difference in the features of disc internal derangement between the ‘progressive-onset' and injury subgroups was seen.
References
- 1.Deyo RA, Tsui-Wu YJ. Descriptive epidemiology of low-back pain and its related medical care in the United States. Spine (Phila Pa 1976) 1987;12:264–268. doi: 10.1097/00007632-198704000-00013. [DOI] [PubMed] [Google Scholar]
- 2.Frymoyer JW. Back pain and sciatica. N Engl J Med. 1988;318:291–300. doi: 10.1056/NEJM198802043180506. [DOI] [PubMed] [Google Scholar]
- 3.Deyo RA, Rainville J, Kent DL. What can the history and physical examination tell us about low back pain? Jama. 1992;268:760–765. [PubMed] [Google Scholar]
- 4.Andersson GB, Svensson HO, Oden A. The intensity of work recovery in low back pain. Spine (Phila Pa 1976) 1983;8:880–884. doi: 10.1097/00007632-198311000-00011. [DOI] [PubMed] [Google Scholar]
- 5.Guyer RD, Ohnmeiss DD. Lumbar discography. Position statement from the North American Spine Society Diagnostic and Therapeutic Committee. Spine. 1995;20:2048–2059. [PubMed] [Google Scholar]
- 6.Fabris G, Lavaroni A, Biasizzo E, et al. Discography: the decisive factor in the choice of percutaneous or surgical treatment of the herniated lumbar disc. In: Du Boulay G, Molyneux A, Mosley I, editors. Neuroradiology; Proceedings of the XIV Symposium Neuroradiologicum; Berlin: Springer-Verlag; 1991. pp. 470–471. [Google Scholar]
- 7.Smedley J, Inskip H, Buckle P, et al. Epidemiological differences between back pain of sudden and gradual onset. J Rheumatol. 2005;32:528–532. [PubMed] [Google Scholar]
- 8.Grubb SA, Lipscomb HJ, Guilford WB. The relative value of lumbar roentgenograms, metrizamide myelography, and discography in the assessment of patients with chronic lo, back syndrome. Spine. 1987;12:282–286. doi: 10.1097/00007632-198704000-00017. [DOI] [PubMed] [Google Scholar]
- 9.Sachs BL, Vanharanta H, Spivey MA, et al. Dallas discogram description. A new classification of CT/discography in low-back disorders. Spine. 1987;12:287–294. doi: 10.1097/00007632-198704000-00018. [DOI] [PubMed] [Google Scholar]
- 10.Bartynski WS, Rothfus WE, Kurs-Lasky M. Postdiscogram CT features of lidocaine-sensitive and lidocaine, insensitive severely painful disks at provocation lumbar discography. Am J Neuroradiol. 2008;29:1455–1460. doi: 10.3174/ajnr.A1151. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Videman T, Malmivaara A, Mooney V. The value of the axial view in assessing discograms. An experimental study with cadavers. Spine. 1987;12:299–304. doi: 10.1097/00007632-198704000-00020. [DOI] [PubMed] [Google Scholar]
- 12.Walsh TR, Weinstein JN, Spratt KF, et al. Lumbar discography in normal subjects. A controlled, prospective study. J Bone Joint Surg Am. 1990;72:1081–1088. [PubMed] [Google Scholar]
- 13.Urban JP, McMullin JF. Swelling pressure of the lumbar intervertebral discs: influence of age, spinal level, composition, and degeneration. Spine (Phila Pa 1976) 1988;13:179–187. doi: 10.1097/00007632-198802000-00009. [DOI] [PubMed] [Google Scholar]
- 14.Haefeli M, Kalberer F, Saegesser D, et al. The course of macroscopic degeneration in the human lumbar intervertebral disc. Spine. 2006;31:1522–1531. doi: 10.1097/01.brs.0000222032.52336.8e. [DOI] [PubMed] [Google Scholar]
- 15.Adams MA, Roughley PJ. What is intervertebral disc degeneration, and what causes it? Spine. 2006;31:2151–2161. doi: 10.1097/01.brs.0000231761.73859.2c. [DOI] [PubMed] [Google Scholar]
- 16.Botwin K, Natalicchio J, Brown LA. Epidurography contrast patterns with fluoroscopic guided lumbar transforaminal epidural injections: a prospective evaluation. Pain Physician. 2004;7:211–215. [PubMed] [Google Scholar]
- 17.Taimela S, Kujala UM, Salminen JJ, et al. The prevalence of low back pain among children and adolescents. A nationwide, cohort, based questionnaire survey in Finland. Spine. 1997;22:1132–1136. doi: 10.1097/00007632-199705150-00013. [DOI] [PubMed] [Google Scholar]
- 18.Leboeuf-Yde C, Kyvik KO. At what age does low back pain become a common problem? A study of 29,424 individuals aged 12-41 years. Spine. 1998;23:228–234. doi: 10.1097/00007632-199801150-00015. [DOI] [PubMed] [Google Scholar]
- 19.Rodriguez DP, Poussaint TY. Imaging of back pain in children. American J Neuroradiol. 2010;31:787–802. doi: 10.3174/ajnr.A1832. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Kjaer P, Leboeuf-Yde C, Sorensen JS, et al. An epidemiologic study of MRI and low back pain in 13-year-old children. Spine. 2005;30:798–806. doi: 10.1097/01.brs.0000157424.72598.ec. [DOI] [PubMed] [Google Scholar]
- 21.Tertti MO, Salminen JJ, Paajanen HE, et al. Low-back pain and disk degeneration in children: a case-control MR imaging study. Radiology. 1991;180:503–507. doi: 10.1148/radiology.180.2.1829844. [DOI] [PubMed] [Google Scholar]
- 22.Erkintalo MO, Salminen JJ, Alanen AM, et al. Development of degenerative changes in the lumbar intervertebral disk: results of a prospective MR imaging study in adolescents with and without low-back pain. Radiology. 1995;196:529–533. doi: 10.1148/radiology.196.2.7617872. [DOI] [PubMed] [Google Scholar]
- 23.Sward L, Hellstrom M, Jacobsson B, et al. Disc degeneration and associated abnormalities of the spine in élite gymnasts. A magnetic resonance imaging study. Spine (Phila Pa 1976) 1991;16:437–443. doi: 10.1097/00007632-199104000-00009. [DOI] [PubMed] [Google Scholar]
- 24.Giroux JC, Leclercq TA. Lumbar disc excision in the second decade. Spine (Phila Pa 1976) 1982;7:168–170. doi: 10.1097/00007632-198203000-00013. [DOI] [PubMed] [Google Scholar]
- 25.Ferrante L, Mastronardi L, Lunardi P, et al. Lumbar disc herniation in teenagers. Eur Spine J. 1992;1:25–28. doi: 10.1007/BF00302138. [DOI] [PubMed] [Google Scholar]
- 26.Kirkaldy-Willis WH, Wedge JH, Yong-Hing K, et al. Pathology and pathogenesis of lumbar spondylosis and stenosis. Spine. 1978;3:319–328. doi: 10.1097/00007632-197812000-00004. [DOI] [PubMed] [Google Scholar]
- 27.Miller JA, Schmatz C, Schultz AB. Lumbar disc degeneration: correlation with age, sex, and spine level in 600 autopsy specimens. Spine (Phila Pa 1976) 1988;13:173–178. [PubMed] [Google Scholar]
- 28.de Schepper EI, Damen J, van Meurs JB, et al. The association between lumbar disc degeneration and low back pain: the influence of age, gender, and individual radiographic features. Spine (Phila Pa 1976) 2010;35:531–536. doi: 10.1097/BRS.0b013e3181aa5b33. [DOI] [PubMed] [Google Scholar]
- 29.Takatalo J, Karppinen J, Niinimaki J, et al. Prevalence of degenerative imaging findings in lumbar magnetic resonance imaging among young adults. Spine (Phila Pa 1976) 2009;34:1716–1721. doi: 10.1097/BRS.0b013e3181ac5fec. [DOI] [PubMed] [Google Scholar]
- 30.Jensen MC, Brant-Zawadzki MN, Obuchowski N, et al. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med. 1994;331:69–73. doi: 10.1056/NEJM199407143310201. [DOI] [PubMed] [Google Scholar]
- 31.Stadnik TW, Lee RR, Coen HL, et al. Annular tears and disk herniation: prevalence and contrast enhancement on MR images in the absence of low back pain or sciatica. Radiology. 1998;206:49–55. doi: 10.1148/radiology.206.1.9423651. [DOI] [PubMed] [Google Scholar]
- 32.Weishaupt D, Zanetti M, Hodler J, et al. MR imaging of the lumbar spine: prevalence of intervertebral disk extrusion and sequestration, nerve root compression, end plate abnormalities, and osteoarthritis of the facet joints in asymptomatic volunteers. Radiology. 1998;209:661–666. doi: 10.1148/radiology.209.3.9844656. [DOI] [PubMed] [Google Scholar]
- 33.Buirski G, Silberstein M. The symptomatic lumbar disc in patients with low-back pain. Magnetic resonance imaging appearances in both a symptomatic and control population. Spine. 1993;18:1808–1811. doi: 10.1097/00007632-199310000-00016. [DOI] [PubMed] [Google Scholar]
- 34.Hancock MJ, Battie MC, Videman T, et al. The role of back injury or trauma in lumbar disc degeneration: an exposure discordant twin study. Spine. 2010;35:1925–1929. doi: 10.1097/BRS.0b013e3181d60598. [DOI] [PubMed] [Google Scholar]
- 35.Roughley PJ. Biology of intervertebral disc aging and degeneration: involvement of the extracellular matrix. Spine. 2004;29:2691–2699. doi: 10.1097/01.brs.0000146101.53784.b1. [DOI] [PubMed] [Google Scholar]
- 36.Schneider S, Randoll D, Buchner M. Why do women have back pain more than men? A representative prevalence study in the federal republic of Germany. Clin J Pain. 2006;22:738–747. doi: 10.1097/01.ajp.0000210920.03289.93. [DOI] [PubMed] [Google Scholar]
- 37.Chenot JF, Becker A, Leonhardt C, et al. Sex differences in presentation, course, and management of low back pain in primary care. Clin J Pain. 2008;24:578–584. doi: 10.1097/AJP.0b013e31816ed948. [DOI] [PubMed] [Google Scholar]
- 38.Freburger JK, Holmes GM, Agans RP, et al. The rising prevalence of chronic low back pain. Arch Intern Med. 2009;169:251–258. doi: 10.1001/archinternmed.2008.543. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 39.van Oostrom SH, Monique Verschuren WM, de Vet HC, et al. Ten year course of low back pain in an adult population-based cohort. The Doetinchem Cohort Study. Eur J Pain. 2011;15:993–998. doi: 10.1016/j.ejpain.2011.02.007. [DOI] [PubMed] [Google Scholar]
- 40.Videman T, Nurminen M, Troup JD. 1990 Volvo Award in clinical sciences. Lumbar spinal pathology in cadaveric material in relation to history of back pain, occupation, and physical loading. Spine (Phila Pa 1976) 1990;15:728–740. [PubMed] [Google Scholar]