Comparison between pain at discography and morphological disc changes at axial loaded MRI in patients with low back pain

Different Load-Induced Alterations in Intervertebral Discs Between Low Back Pain Patients and Controls: A T2-map Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

Investigate load-induced effects in lumbar intervertebral discs (IVDs) and differences between low back pain (LBP) patients and controls.

SUMMARY OF BACKGROUND DATA

T2-map values, obtained from quantitative MRI sequences, reflect IVD tissue composition and integrity. Feasibility studies with T2-mapping indicate different load-induced effects in entire IVDs and posterior IVD parts between LBP patients and controls. Larger studies are required to confirm these findings and increase the understanding of specific characteristics distinguishing IVD changes in LBP patients compared with controls.

MATERIALS AND METHODS

Lumbar IVDs of 178 patients (mean age: 43.8 yr; range: 20-60 yr) with >3 months of LBP and 74 controls (mean age: 40.3 yr; range: 20-60 yr) were imaged with T2-map sequence in a 3T scanner in supine position without axial load, immediately followed by a repeated examination, using the same sequence, with axial load. On both examinations, mean T2-map values were obtained from entire IVDs and from central/posterior IVD parts on the three midsagittal slices in 855 patient IVDs and 366 control IVDs. Load-induced effect was compared with Fold-change ratio and adjusted for IVD-degeneration grade.

RESULTS

Loading induced an increase in T2-map values in both patients and controls. Excluding most extreme values, the ranges varied between -15% and +35% in patients and -11% and +36% in controls (first to 99th percentile). Compared with controls, the T2-map value increase in patients was 2% smaller in entire IVDs (Fold-change: 0.98, P =0.031), and for central and posterior IVD parts 3% (Fold-change: 0.98, P =0.005), respectively, 2% (Fold-change: 0.9, P =0.015) smaller.

CONCLUSIONS

This quantitative study confirmed diverse load-induced behaviors between LBP patients and controls, suggesting deviant biomechanical characteristics between IVDs in patients and controls not only attributed to the global grade of degeneration. These findings are an important step in the continuous work of identifying specific IVD phenotypes for LBP patients.

LEVEL OF EVIDENCE

Level II.

High glucose enhances fibrosis in human annulus fibrosus cells by activating mTOR, PKCδ, and NF-κB signaling pathways

Low back pain stands as a significant factor in disability, largely resulting from intervertebral disc degeneration (IVDD). High glucose (HG) levels have been implicated in the pathogenesis of IVDD. However, the detailed mechanism of HG in IVDD is largely unknown. Our clinical results revealed that fibrosis markers such as CTGF, Col1a1, ATF4, and EIF2 are highly expressed in advanced-stage IVDD patients. Stimulation of human annulus fibrosus cells (HAFCs) with HG, but not mannitol, promotes fibrosis protein production. Ingenuity Pathway Analysis in the GSE database found that the mTOR, PKCδ, and NF-κB pathways were significantly changed during IVDD. The mTOR, PKCδ, and NF-κB inhibitors or siRNAs all abolished HG-induced fibrosis protein production. In addition, treatment of HAFCs with HG enhances the activation of mTOR, PKCδ, and NF-κB pathways. Thus, HG facilitates fibrosis in IVDD through mTOR, PKCδ, and NF-κB pathways. These results underscore the critical role of HG as a fibrotic factor in the progression of IVDD.

Frequency of use of discography findings for the diagnosis of low back pain of discogenic origin. Systematic review of the literature

INTRODUCTION

There are different techniques and interpretations of discography findings to determine it positive for the diagnosis of discogenic pain. This study aims to evaluate the frequency of use of discography findings for the diagnosis of low back pain of discogenic origin.

MATERIAL AND METHODS

A systematic review of the literature of the last 17 years was performed in MEDLINE and BIREME. A total of 625 articles were identified, 555 were excluded for duplicates, title and abstract. We obtained 70 full texts of which 36 were included in the analysis after excluding 34 for not meeting the inclusion criteria.

RESULTS

Among the criteria in discography to determine it as positive, 8 studies used only the pain response to the procedure, 28 studies used more than one criterion during discography to consider it as positive, the evaluation of at least one adjacent intervertebral disc with a negative result was necessary in 26 studies to consider a discography as positive. Five studies formally expressed the use of the technique described by SIS/IASP to determine a discography as positive.

CONCLUSIONS

Pain in response to contrast medium injection, assessed with the visual analog pain scale≥6, was the most used criterion in the studies included in this review. Although there are already criteria to determine a discography as positive, the use of different techniques and interpretations of discography findings to determine a positive discography for low back pain of discogenic origin persists.

[Translated article] Frequency of use of discography findings for the diagnosis of low back pain of discogenic origin. Systematic review of the literature

INTRODUCTION

There are different techniques and interpretations of discography findings to determine it positive for the diagnosis of discogenic pain. This study aims to evaluate the frequency of use of discography findings for the diagnosis of low back pain of discogenic origin.

MATERIAL AND METHODS

A systematic review of the literature of the last 17 years was performed in MEDLINE and BIREME. A total of 625 articles were identified, 555 were excluded for duplicates, title and abstract. We obtained 70 full texts of which 36 were included in the analysis after excluding 34 for not meeting the inclusion criteria.

RESULTS

Among the criteria in discography to determine it as positive, 8 studies used only the pain response to the procedure, 28 studies used more than one criterion during discography to consider it as positive, the evaluation of at least one adjacent intervertebral disc with a negative result was necessary in 26 studies to consider a discography as positive. Five studies formally expressed the use of the technique described by SIS/IASP to determine a discography as positive.

CONCLUSIONS

Pain in response to contrast medium injection, assessed with the visual analogue pain scale ≥6, was the most used criterion in the studies included in this review. Although there are already criteria to determine a discography as positive, the use of different techniques and interpretations of discography findings to determine a positive discography for low back pain of discogenic origin persists.

Comparison of Clinical and Radiographic Outcomes Between Transforaminal Endoscopic Lumbar Discectomy and Microdiscectomy: A Follow-up Exceeding 5 Years

OBJECTIVE

To compare the long-term clinical and radiographic outcomes of transforaminal endoscopic lumbar discectomy (TELD) versus microdiscectomy (MD).

METHODS

The data of 154 patients with lumbar disc herniation (LDH) who underwent TELD (n = 89) or MD (n = 65) were retrospectively analyzed. The patients' clinical outcomes were evaluated using visual analogue scales for leg and low back pain, the Japanese Orthopaedic Association (JOA) score, and the Oswestry Disability Index (ODI). The evolution of radiographic manifestations was observed during follow-up. Potential risk factors for a poor clinical outcome were investigated.

RESULTS

During a mean follow-up of 5.5 years (range, 5-7 years), the recurrence rate was 4.49% in the TELD group and 1.54% in the MD group. All scores significantly improved from preoperatively to postoperatively in both groups (p < 0.01). The improvement in the ODI and JOA scores was significantly greater in the TELD than MD group (p < 0.05). Forty-seven patients (52.8%) in the TELD group and 32 (49.2%) in the MD group had Modic changes before surgery, most of which showed no changes at the last follow-up. The degeneration grades of 292 discs (71.0%) were unchanged at the last follow-up, while 86 (20.9%) showed improvement, mostly at the upper adjacent segment. No significant difference was observed in the intervertebral height index or paraspinal muscle-disc ratio.

CONCLUSION

Both TELD and MD provide generally satisfactory long-term clinical outcomes for patients with LDH. TELD can be used as a reliable alternative to MD with less surgical trauma. Modic type II changes, decreased preoperative intervertebral height, and a high body mass index are predictors of a poor prognosis.

Are there any correlations among the number of discopathy levels and pain intensity or disability in patients with symptomatic low back pain?

INTRODUCTION

Low back pain (LBP) is considered a civilization disease that affects people in an increasing number. Discopathy (degeneration of intervertebral discs) is recognised as one of LBP causes. Still, the relationship between the number of discopathy levels and LBP remains unclear. The aim of this study was to evaluate the correlation between the number of discopathy levels with intensity of LBP, functional level and the degree of disability.

MATERIALS AND METHODS

The prospective, cohort study involved 200 patients aged 27 to 55 years (44.9 ± 9.2 years) with single- or multilevel lumbar discopathy confirmed by imaging examinations. Functional examination included NRSscale, goniometric measurements, Modified Laitinen Pain Questionnaire, Oswestry Disability Index and Back Pain Function Scale.

RESULTS

There were statistically significant positive correlations between the number of discopathy levels and the age of the subjects (r = 0.266; p = 0.000), BMI (r = 0.158; p = 0.029) and ODI (r = 0.157; p = 0.026). Positive correlation (r = 0.142; p = 0.044) was also observed between the results of Fingertip-to-floortest and the number of levels of discopathy.

CONCLUSIONS

The number of levels of discopathy was depended on the age and BMI of the patients. It had no effect on pain intensity, range of rotational motion of the lumbar spine and functional status of patients. As the number of levels of discopathy increased, a higher degree of everyday disability was observed.

Loading of the Spine in Low Back Pain Patients Does Not Induce MRI Changes in Modic Lesions: A Prospective Clinical Study

Modic changes (MCs) are gaining increased interest as potential generators of low back pain (LBP). The current aim was to investigate possible spinal loading effects on the MRI signal in MCs in patients with LBP. Supine lumbar MRIs were performed and immediately repeated with axial loading in 100 LBP patients. A total of 43 patients (23 male, mean age 45.7 years) had MCs. Each Modic was outlined on all sagittal T2-weighted images (>25% affected vertebrae). For reference, regions of interest were placed in both vertebrae without Modic and in Modic-free tissue in vertebrae with Modic. The Modic signal intensity, normalized to cerebrospinal fluid, and Modic volume were compared between MRIs with and without spinal loading. Of the 94 MCs, 36.2% (n = 34) were type I, 58.5% (n = 55) were type II, and 5.3% (n = 5) were type III. No differences in Modic volume (mean 0.046 cm3; p = 0.25) between the MRIs with and without spinal loading were found. In addition, no significant changes in Modic signal were induced by loading (mean 1.5% difference; p = 0.308). Loading increased the signal in the reference regions of interest in vertebrae both with Modic (mean 5.5%; p = 0.002) and without (mean 3.5%; SD 0.09; p = 0.02). To conclude, MRIs performed with and without spinal loading showed no change in either volume or signal of MCs, suggesting that most MCs are not instantaneously influenced by biomechanical load.

Interpretation of Morphological Details of Nondegenerated Lumbar Intervertebral Discs on Magnetic Resonance Imaging: Insights From a Comparison Between Computed Tomography Discograms and Magnetic Resonance Imaging

OBJECTIVE

To gain better insight into the magnetic resonance imaging (MRI) appearance of morphological intervertebral disc (IVD) details, such as annular and nucleus pulposus dimensions, by comparing contemporaneously obtained MRI and postdiscogram computed tomography (CT) scans of nondegenerated IVDs.

METHODS

Axial T2-weighted images and same-day postdiscography CTs, acquired after the MRI, of 26 normal-appearing lumbar IVDs (control IVDs at discography) were compared. The location and extent of central hyperintense zone on MRI and the extent of contrast distribution on CT relative to the IVD width (in anteroposterior [AP] and lateral planes) were assessed, with difference in measures between the modalities used to provide apparent inner annulus thickness and to estimate dimensions of also the outer annulus and location of nucleus pulposus.

RESULTS

The mean (SD) extent of contrast distribution on CT discograms (53.1% [6.6%] and 58.1% [8.7%] of AP and lateral IVD width) was smaller than (P < 0.001 for both), and correlated weakly (r = 0.31 and 0.32 for AP and lateral planes) with corresponding measurements (58.4% [5.3%] and 65.7% [5.9%], respectively) for central hyperintense zone at MRI. The center of contrast opacification on CT discograms was located posterior to that of central T2 hyperintense zone on MRI in AP (P < 0.01), without any difference in lateral direction (P = 0.60).

CONCLUSIONS

Normal-appearing lumbar IVDs are supported by outer annulus of larger relative thickness anteriorly, seen on both modalities. The shown discrepancy between the central T2 hyperintense zone and contrast distribution on CT discogram might reflect the inner annulus or structural changes within the borderzone nucleus and annulus. The exact nucleus size and inner annulus thickness could not be established due to a variable permeation of contrast across the central hyperintense zone on T2-weighted images.

Suggested Applications of Musculoskeletal Ultrasound to Identify the Etiologies of Low Back Pain

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Disc height discrepancy between supine and standing positions as a screening metric for discogenic back pain in patients with disc degeneration

BACKGROUND CONTEXT

The diagnosis of discogenic low back pain (LBP) from disc degeneration of the lumbar spine is often evaluated with discography. Noninvasive, simple screening methods other than invasive discography are useful, as evidence supporting clinical findings and magnetic resonance imaging (MRI) have come to the forefront.

PURPOSE

To investigate disc height (DH) discrepancy between supine and standing positions on simple radiography to clarify its clinical screening value in individuals with discogenic LBP.

STUDY DESIGN/SETTINGS

Retrospective matched cohort design.

PATIENT SAMPLE

Ninety-two patients with early to middle stage disc degeneration (Pfirrmann grade II, III, or IV).

OUTCOME MEASURES

Each subject underwent simple radiographs and MRI. Baseline characteristics, including demographic data and MRI findings, and radiological findings, including DH discrepancy, segmental angle, and sagittal balance, were analyzed. DH discrepancy ratio was calculated as (1 - [calibrated DH on standing radiography/calibrated DH on supine radiography]) × 100%.

METHODS

We matched LBP group of 46 patients with intractable discogenic pain (≥7 of visual analog scale scores) confirmed by discography with control group of 46 patients with similar stage disc degeneration with mild LBP (≤4 of visual analog scale scores). Binary regression analysis, receiver operating characteristic curve analysis, and cut-off value for diagnosis were used to evaluate and clarify diagnostic value of various factors.

RESULTS

There was no significant difference between the two groups in terms of baseline characteristics, including age, sex, body mass index, pathological level, and magnetic resonance findings such as disc degeneration, high intensity zone, and para-spinal muscle volume. Among the various radiological findings, the calibrated mean DH in the standing position (20.87±5.65 [LBP group] vs. 26.95±3.02 [control group], p<.001) and the DH discrepancy ratio (14.55±6.13% [LBP group] vs. 1.47±0.75% [control group], p=.007) were significantly different between the two groups. The cut-off value for DH discrepancy ratio to screen discogenic LBP was ≥6.04%. Additionally, as a compensation for pain, sagittal vertical axis (3.43±2.03 cm [LBP group] vs. -0.54±3.05 cm [control group], p=.002) and pelvic incidence (54.74±6.76° [LBP group] vs. 43.98±8.67° [control group]; p=.006) were different between the two groups.

CONCLUSIONS

The results suggest that DH discrepancy between the supine and standing positions could be a screening metric for discogenic LBP in early to middle stage disc degeneration of the lumbar spine.

Axial loading during MRI induces significant T2 value changes in vertebral endplates-a feasibility study on patients with low back pain

BACKGROUND

The function of the endplate (EP) is the most important factor influencing nutritional supply to the avascular intervertebral disc (IVD). It is desired to have a non-invasive method to assess functional EP characteristics in vivo. Assessment of functional EP characteristics is important in order to understand its relation to IVD degeneration, which in turn might deepen the understanding of the pathophysiology behind low back pain (LBP). It was hypothesized that, by comparing quantitative MRI of EPs performed with conventional supine MRI (unloaded MRI) with axial loading during MRI (alMRI), dynamical properties of the EP can be displayed. The aim was therefore to investigate the feasibility of axial loading during MRI (alMRI) to instantaneously induce quantitative EP changes.

METHODS

T2 mapping of 55 vertebral EPs (L1-S1) in five LBP patients was performed during conventional supine MRI (unloaded MRI) and subsequent alMRI. With T2 mapping, the cartilaginous EP and bony EP cannot be separated; hence, the visualized EP was termed EP zone (EPZ). Each EPZ was segmented at multiple midsagittal views, generating volumetric regions of interest. EPZs demonstrating signal inhomogeneity and/or adjacent Modic changes (MC) were termed abnormal EPZs. EPZ mean T2 values were compared between unloaded MRI and alMRI, and their relationship with abnormal EPZs was determined.

RESULTS

alMRI induced significantly higher (p = 0.01) EPZ mean T2 values compared with unloaded MRI. Significantly higher mean T2 values were seen in inferior EPZs compared with superior EPZs, both with unloaded MRI (35%, p < 0.001) and with alMRI (26%, p = 0.04). Significant difference between unloaded MRI and alMRI was seen in normal (p = 0.02), but not in abnormal EPZs (p = 0.5; n = 12).

CONCLUSIONS

alMRI induces changes in human EPZ characteristics in vivo. The T2 value significantly increased in normal EPZs, with lack of such in abnormal EPZs. Combining T2 mapping with alMRI provides a clinical feasible, non-invasive method with potential to reveal biochemical behavioral patterns, thus adding another dimension of the EPZs characteristics compared with information obtained with solely unloaded MRI.

With axial loading during MRI diurnal T2-value changes in lumbar discs are neglectable: a cross sectional study

Background

Axial loading during MRI (alMRI) combined with T2 mapping recently was shown as a promising method to reveal biomechanical intervertebral disc (IVD) characteristics. This feasibility study aims to investigate whether there is a diurnal variation in the IVD T2-value when using alMRI. This is of importance for the planning of when to perform alMRI investigations and for interpretations of alMRI findings in relation to clinical symptoms.

Methods

Six healthy volunteers (30 lumbar discs), were examined with alMRI at three different sessions during 1 day. To be representative for a low back pain cohort in terms of age and IVD degeneration the included participants had a wide age range (27-63y) and all Pfirrmann grades represented. The T2-values were measured in five IVD regions of interest (ROI). The ROIs were equally large in sagittal plane with ROI1 representing anterior parts of the IVD, ROI5 posterior IVD parts and ROI2–4 the parts in between.

Results

T2-values of the entire IVD varied between 38 and 138 ms at 7 am, 33-143 ms at 11.30 am, and 31-147 ms at 4 pm with large regional IVD variations at all time points. No significant alterations of the T2-values over the day were found, neither for the entire IVD (p = 0.4) nor for the various ROIs (p = 0.2–1.0). Neither when correlated to Pfirrmann grade, any significant diurnal T2-value changes were found.

Conclusions

With alMRI, only minor diurnal T2-value changes were found in the lumbar discs. Nonsignificant and neglectable diurnal changes are advantageous both for research purposes, as well as in the clinical setting, giving comparable and robust data regardless of at what time-point the alMRI is performed.

Axial loading during MRI influences T2-mapping values of lumbar discs: a feasibility study on patients with low back pain

PURPOSE

To investigate whether axial loading of the spine during MRI (alMRI) instantaneously induces changes in biochemical disc features as reflected by altered quantitative T2 values in patients with chronic low back pain (LBP).

METHODS

T2 mapping was performed on 11 LBP patients (54 lumbar discs) during the conventional unloaded MRI and subsequent alMRI. Each disc was divided into five volumetric regions of interests (ROIs), anterior annulus fibrosus (AF) (ROI 1), the interface anterior AF-nucleus pulposus (NP) (ROI 2), NP (ROI 3), the interface NP-posterior AF (ROI 4), and the posterior AF (ROI 5). The mean T2 values for each ROI were compared between MRI and alMRI and correlated with degeneration grade (Pfirrmann), disc angle, and disc level.

RESULTS

With alMRI, T2 values increased significantly in the whole disc as well as in various parts of the disc with an increase in ROI 1-3 and a decrease in ROI 5. The changes in T2 values correlated to degeneration grade, changes in disc angle, and lumbar level.

CONCLUSION

alMRI instantaneously induces T2-value changes in lumbar discs and is, thus, a feasible method to reveal dynamic, biochemical disc features in patients with chronic LBP.