Hanna Hebelka

The narrowing of the lumbar spinal canal during loaded MRI: the effects of the disc and ligamentum flavum

Load and activity changes of the spine typically cause symptoms of nerve root compression in subjects with spinal stenosis. Protrusion of the intervertebral disc has been regarded as the main cause of the compression. The objective was to determine the changes in the size of the lumbar spinal canal and especially those caused by the ligamentum flavum and the disc during loaded MRI. For this purpose an interventional clinical study on consecutive patients was made. The lumbar spines in 24 supine patients were examined with MRI: first without any external load and then with an axial load corresponding to half the body weight. The effect of the load was determined through the cross-sectional areas of the spinal canal and the ligamentum flavum, the thickness of ligamentum flavum, the posterior bulge of the disc and the intervertebral angle. External load decreased the size of the spinal canal. Bulging of the ligamentum flavum contributed to between 50 and 85% of the spinal canal narrowing. It was concluded that the ligamentum flavum, not the disc had a dominating role for the load induced narrowing of the lumbar spinal canal, a finding that can improve the understanding of the patho-physiology in spinal stenosis.

The transfer of disc pressure to adjacent discs in discography: a specificity problem?

Study Design. In vivo experimental study. Objective. The primary objective of the study was to investigate pressure transmission to adjacent discs during discography. A secondary objective was to quantify the transmitted pressure, both in contrast injected and noninjected porcine intervertebral discs. Summary of Background Data. Discography is used to before surgery identify painful discs. A pain response during discography that is concordant with the patients experienced back pain is regarded as an indication that the injected disc is the source of pain. However, the sensitivity and specificity of discography are matters of debate. Pressure-controlled discographies have been reported to reduce the number of false-positive discs using low pressure criteria. Preliminary data indicated a transfer of pressure from an injected to an adjacent disc during discography. Pressure transmission in vivo during lumbar discography, not reported before might, if clinically present, contribute to a false-positive diagnosis. Methods. Thirty-six lumbar discs in 9 adolescent pigs were investigated. Intradiscal pressure was recorded during contrast injection, using a 0.36/0.25 mm fiber-optic pressure transducer inserted into the nucleus pulposus via a 22 G needle. The pressure was measured simultaneously in 2 adjacent discs during contrast injection into 1 of the discs at pressures up to 8 bar. Transmitted pressure was recorded both in noninjected discs and in discs that were prefilled with contrast. Results. Thirty-three discs were successfully examined. During contrast injection, there was an intradiscal pressure rise in the adjacent disc with a median value of 16.0% (range, 3.2–37.0) over baseline pressure. There was no significant difference in pressure increase between the noninjected and prefilled discs (P < 0.68). Conclusion. Discography of porcine discs induces a pressure increase in adjacent discs. A similar pressure transfer during human clinical discography might elicit false-positive pain reactions.

HIZ’s relation to axial load and low back pain: investigated with axial loaded MRI and pressure controlled discography

Purpose The aims were to investigate if the detection of high-intensity zones (HIZ) is affected by axial load, and to study the correlation between HIZ and discogenic pain provoked with pressure controlled discography (PCD).

Pressure Increase in Adjacent Discs During Clinical Discography, Questions the Methods Validity.

Study Design. Observational in vivo clinical study. Objective. To investigate whether intradiscal pressure is transferred to adjacent discs during clinical discography in subjects with discogenic pain. Summary of Background Data. Despite the introduction of pressure registration in discography, the validity of the method remains controversial. Discography in vivo in anesthetized pigs has shown that the pressure increase during disc injection is transmitted to adjacent discs. If pressure transmission is confirmed in human spines, it could be a potential source of false-positive discography responses. Methods. Twenty-five discograms were performed in 9 consecutive patients. A pressure sensor was introduced through a 22-gauge needle into the nucleus pulposus in 2 adjacent discs. Contrast was injected with a manometer (∼0.05 mL/s) into one of the discs, whereas intradiscal pressure was measured simultaneously in both discs. The injection continued until one of the endpoints was reached; concordant pain with an intensity of 5/10 or more, intradiscal pressure of 80 psi (absolute pressure), and/or 3.5-mL contrast volume. Results. Intradiscal pressure was successfully measured in 22 adjacent discs of which 7 were not filled with contrast and 15 were prefilled from the previous discogram. A mean pressure increase of 13 psi (range, 3–42 psi) was recorded in 55% (12) of the adjacent discs, corresponding to an increase of 62% above baseline. Of discograms inducing pressure transmission, all had Pfirrmann degeneration grade of 3 or more and, of adjacent discs with increased pressure, 75% had degeneration of 3 or more. Maximum pressure in injected discs averaged 35 psi above opening pressure (range, 10–69 psi). Conclusion. Clinical discography induces a pressure increase in adjacent discs. The induced pressure increase was of a clinically relevant magnitude and was evident despite low absolute pressures in the injected disc. Pressure transmission during discography constitutes a potential major source of false-positive responses, questioning the ability of discography to provoke pain at just a single disc level. Level of Evidence: 1

In vivo discography in degenerate porcine spines revealed pressure transfer to adjacent discs.

Study Design. In vivo experimental porcine study. Objective. To investigate if discography induced pressure increase in adjacent degenerate discs. Summary of Background Data. Despite refinements in the past 2 decades, the validity of discography is debated. Discography in healthy pigs has shown that the pressure increase during disc injection transmits to adjacent discs, a potential source for false positive responses. Methods. Degeneration in 1 lumbar disc was induced in 10 pigs by drilling a hole through the endplate. Intradiscal pressure was recorded using a 0.36-mm fiber-optic pressure transducer inserted into nucleus pulposus through a 22-gauge needle. The pressure was measured simultaneously in 2 adjacent discs during slow (0.03 mL/s) automated contrast injection into 1 of the discs up to 8 bar (116 psi). Ten adjacent discs were prefilled with contrast from previous discogram. A pressure increase 2 psi or more above baseline was defined as increased pressure in adjacent discs. Pressure was recorded until 15 minutes after injection. Results. A total of 28 discograms were successfully performed. A pressure increase during injection was detected in 57% (16) of the 28 adjacent discs with mean 3.2 psi (1.7–8.2; standard deviation, 1.8), corresponding to a mean increase above baseline of 11%. Of those 16 adjacent discs, 4 were nondegenerate and 12 degenerate, of which 7 were prefilled. Fifteen minutes after injection, 89% of adjacent discs displayed increase in pressure of mean 14% above baseline. Conclusion. Discography induced pressure increase in adjacent discs in a degenerate disc model, something not reported earlier. If present, also in human spine pressure transmission, may be a potential cause for false positive discography responses. Level of Evidence: 3

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

PurposeTo 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).MethodsT2 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.ResultsWith 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.ConclusionalMRI 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.

Degenerative Changes in the Cervical Spine Are More Common in Middle-Aged Individuals with Thalidomide Embryopathy than in Healthy Controls

Background Thalidomide was used as a sedative drug for pregnant women in the 1950–60:s and resulted in children born with thalidomide embryopathy (TE), including upper limb malformations. These may alter the motion pattern of the cervical spine by the use of head/shoulder and mouth grip. Aims To compare degenerative changes in the cervical spine in TE individuals with healthy controls (CTR). Methods and Procedures Twenty-seven middle-aged TE individuals and 27 age- and gender-matched CTR were examined by cervical spine MRI. The presence of malformations, disc herniation(s), osteophytes, nerve and medullary compression and the degree of disc degeneration (DD) were evaluated. Outcomes and Results Significantly higher degree of DD was seen in the TE group compared with the controls (p<0.001). Similar frequencies of disc herniation and disc space narrowing were observed in the two groups, but more foraminal narrowing was seen in the TE group (p = 0.002). DD was observed relatively frequently at all cervical levels in the TE group, however, mainly at the two lower levels in the CTR. Conclusions and Implications Middle-aged individuals with TE have a higher frequency of degenerative changes in the cervical spine than controls, possibly caused by an altered load on the cervical spine.

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

BackgroundThe 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.MethodsT2 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.ResultsalMRI 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).ConclusionsalMRI 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.

Degenerative Changes in the Cervical Spine are More Common in Middle-aged Patients with Thalidomide Embryopathy than in Healthy Individuals

Introduction The aim of the study was to compare the degree of degenerative changes in the cervical spine of thalidomide embryopathy (TE) patients−in whom upper limb malformations often necessitate help with grip function through the mouth or by head motion, and may thereby add extra load to the spine−with that in a control group (CTR). Material and Methods Twenty-seven middle-aged TE patients and 27 age- and gender-matched healthy CTR were examined by cervical MRI. The presence of malformations, disc herniations, osteophytes, nerves and medullary compression, were evaluated. Disc degenerations (DD), were graded according to the Pfirrmann classification. Results Similar frequencies of disc herniation and disc space narrowing were observed in both groups, but there was more foraminal narrowing in the TE group (ρ < 0.002). Significantly more DD were seen in the TE group than in the controls (ρ < 0.001). Evaluation of all discs (n = 135 per group) showed Pfirrmann grade I in 0% of the TE group and 2% of the controls. Grade II was found in 3% and 36%, respectively, grade III in 46% and 50%, grade IV in 38% and 11%, and grade V in 13% and 0% (ρ < 0.001). DD were observed frequently at all levels for the TE group, however mainly in the two lower levels for the CTR. Conclusion The more frequently observed degenerative changes of foraminal narrowing and disc signal changes in the TE group support the theory that a higher load on the cervical spine leads to earlier development of DD.