Dynamic changes in the dimensions of the lumbar spinal canal: an experimental study in vitro

Feasibility of deep learning algorithm in diagnosing lumbar central canal stenosis using abdominal CT

OBJECTIVE

To develop a deep learning algorithm for diagnosing lumbar central canal stenosis (LCCS) using abdominal CT (ACT) and lumbar spine CT (LCT).

MATERIALS AND METHODS

This retrospective study involved 109 patients undergoing LCTs and ACTs between January 2014 and July 2021. The dural sac on CT images was manually segmented and classified as normal or stenosed (dural sac cross-sectional area ≥ 100 mm2 or < 100 mm2, respectively). A deep learning model based on U-Net architecture was developed to automatically segment the dural sac and classify the central canal stenosis. The classification performance of the model was compared on a testing set (990 images from 9 patients). The accuracy, sensitivity, and specificity of automatic segmentation were quantitatively evaluated by comparing its Dice similarity coefficient (DSC) and intraclass correlation coefficient (ICC) with those of manual segmentation.

RESULTS

In total, 990 CT images from nine patients (mean age ± standard deviation, 77 ± 7 years; six men) were evaluated. The algorithm achieved high segmentation performance with a DSC of 0.85 ± 0.10 and ICC of 0.82 (95% confidence interval [CI]: 0.80,0.85). The ICC between ACTs and LCTs on the deep learning algorithm was 0.89 (95%CI: 0.87,0.91). The accuracy of the algorithm in diagnosing LCCS with dichotomous classification was 84%(95%CI: 0.82,0.86). In dataset analysis, the accuracy of ACTs and LCTs was 85%(95%CI: 0.82,0.88) and 83%(95%CI: 0.79,0.86), respectively. The model showed better accuracy for ACT than LCT.

CONCLUSION

The deep learning algorithm automatically diagnosed LCCS on LCTs and ACTs. ACT had a diagnostic performance for LCCS comparable to that of LCT.

Association between sarcopenia and intervertebral disc degeneration: A bidirectional two-sample Mendelian randomization

BackgroundSarcopenia (SP) and Intervertebral Disc Degeneration (IVDD) are common age-related diseases that significantly affect the physical and mental health of patients. A substantial body of evidence suggests a potential association between SP and IVDD. However, the causal relationship between SP and IVDD remains uncertain.ObjectivesThis study aimed to determine whether the association between SP and IVDD is causal by employing Mendelian randomization (MR) analysis.MethodsGenome-wide association study (GWAS) data related to SP (measured by muscle lean mass, left- and right-hand grip strength, and walking speed) and IVDD were obtained from the UK Biobank and FinnGen. To investigate the causal relationship between SP and IVDD, three MR analysis methods were employed, primarily focusing on the Inverse-Variance Weighted (IVW) approach. The robustness of causal effects was ensured through multiple methods: Instrumental Variables (IVs) were evaluated using F-values; heterogeneity was assessed using Cochran's Q; horizontal pleiotropy was evaluated using MR Egger regression; and outliers was detected using MR-PRESSO and the leave-one-out method.ResultsThe analysis indicates a potential causal relationship between appendicular lean mass (ALM) and the risk of IVDD (OR = 0.89, 95% CI: 0.809-0.98; P < 0.05). Similarly, left-hand grip strength shows a potential causal relationship with IVDD risk (OR = 1.52, 95% CI:1.08-2.14; P < 0.05), as does right-hand grip strength (OR = 1.50, 95% CI:1.09-2.07; P < 0.05). Additionally, a potential causal relationship is observed between IVDD and walking speed (OR = 0.99, 95% CI:0.97-1.00; P < 0.05).ConclusionThe findings suggest that ALM may serve as a protective factor against IVDD, while left- and right-hand grip strength may be risk factors for the development of IVDD. Furthermore, IVDD appears to be a risk factor associated with reduced walking speed. Further research is necessary to elucidate the underlying mechanisms of these associations.

Diagnostic efficacy of nerve root sedimentation sign in post-lumbar interbody fusion patients: an imaging evaluation and modification

BACKGROUND

The sedimentation sign offers an efficient method for evaluating lumbar spinal stenosis. However, limited research exists regarding its applicability to post-operative MRI scans. This study aims to assess the viability of utilizing the nerve root sedimentation sign (NRSS) and Schizas classification (SC) in the evaluation of post-operative lumbar stenosis.

METHODS

Patients were classified into seven groups using SC: A1, A2, A3, A4, B, C and D. The dural sac cross-sectional area (DSCA), anterior-posterior dural sac diameter (AP), and the Oswestry disability index (ODI) of each group were compared. The difference in DSCA between direct and indirect decompression surgery was also compared to confirm whether the deformation of the spinal canal will affect the results.

RESULTS

232 postoperative patients were evaluated. The variance of analysis showed that DCSA, AP and ODI had significant differences among the SC groups and NRSS groups postoperatively (P < 0.01). Comparison of DSCA results between direct and indirect decompression postoperative patients showed significant differences between groups A1 and A2, A2 and A3. AP comparison results showed significant differences between groups A1 and A2. ODI comparison results showed significant differences between groups A2 and A3. Among OLIF patients, groups A1 and A2 had mean DSCA values greater than 100mm2, while in the T/PLIF group, groups A1-4 had mean DSCA values greater than 100mm2.

CONCLUSION

Both sedimentation signs are applicable for the evaluation of postoperative lumbar spinal stenosis. We recommend updating the definition of negative nerve root sedimentation sign to nerve root sedimentation on the dorsal side of the dural sac, with an occupying area less than half, and greater than half considered positive sign. Sedimentation sign is mainly formed by the interaction of gravity, extradural pressure, and nerve root tension.

Factors that influence the results of indirect decompression employing oblique lumbar interbody fusion

BACKGROUND

Indirect decompression is one of the potential benefits of anterior reconstruction in patients with spinal stenosis. On the other hand, the reported rate of revision surgery after indirect decompression highlights the necessity of working out prediction models for the radiographic results of indirect decompression with assessing their clinical relevance.

AIM

To assess factors that influence radiographic and clinical results of the indirect decompression in patients with stenosis of the lumbar spine.

METHODS

This study is a single-center cross-sectional evaluation of 80 consecutive patients (17 males and 63 females) with lumbar spinal stenosis combined with the instability of the lumbar spinal segment. Patients underwent single level or bisegmental spinal instrumentation employing oblique lumbar interbody fusion (OLIF) with percutaneous pedicle screw fixation. Radiographic results of the indirect decompression were assessed using computerized tomography, while MacNab scale was used to assess clinical results.

RESULTS

After indirect decompression employing anterior reconstruction using OLIF, the statistically significant increase in the disc space height, vertebral canal square, right and left lateral canal depth were detected (Р < 0.0001). The median (M) relative vertebral canal square increase came to М = 24.5% with 25%-75% quartile border (16.3%; 33.3%) if indirect decompression was achieved by restoration of the segment height. In patients with the reduction of the upper vertebrae slip, the median of the relative increase in vertebral canal square accounted for 49.5% with 25%-75% quartile border (2.35; 99.75). Six out of 80 patients (7.5%) presented with unsatisfactory results because of residual nerve root compression. The critical values for lateral recess depth and vertebral canal square that were associated with indirect decompression failure were 3 mm and 80 mm2 respectively.

CONCLUSION

Indirect decompression employing anterior reconstruction is achieved by the increase in disc height along the posterior boarder and reduction of the slipped vertebrae in patients with degenerative spondylolisthesis. Vertebral canal square below 80 mm2 and lateral recess depth less than 3 mm are associated with indirect decompression failures that require direct microsurgical decompression.

Time Course of Asymptomatic Stenosis in Multiple Lumbar Spinal Stenosis-Five-Year Results of Selective Decompression of Symptomatic Levels

Background: In the diagnosis of lumbar spinal stenosis (LSS), finding stenosis with magnetic resonance imaging (MRI) does not always correlate with symptoms such as sciatica or intermittent claudication. We perform decompression surgery only for cases where the levels diagnosed from neurological findings are symptomatic, even if multiple stenoses are observed on MRI. The objective of this study was to examine the time course of asymptomatic stenosis in patients with LSS after they underwent decompression surgery for symptomatic stenosis. Materials and Methods: The participants in this study comprised 137 LSS patients who underwent single-level L4-5 decompression surgery from 2003 to 2013. The dural sac cross-sectional area at the L3-4 disc level was calculated based on preoperative MRI. A cross-sectional area less than 50 mm2 was defined as stenosis. The patients were grouped, according to additional spinal stenosis at the L3-4 level, into a double group (16 cases) with L3-4 stenosis, and a single group (121 cases) without L3-4 stenosis. Incidences of new-onset symptoms originating from L3-4 and additional L3-4-level surgery were examined. Results: Five years after surgery, 98 cases (72%) completed follow-up. During follow-up, 2 of 12 patients in the double group (16.7%) and 9 of 86 patients in the single group (10.5%) presented with new-onset symptoms originating from L3-4, showing no significant difference between groups. Additional L3-4 surgery was performed for one patient (8.3%) in the double group and three patients (3.5%) in the single group; again, no significant difference was shown. Conclusion: Patients with asymptomatic L3-4 stenosis on preoperative MRI were not prone to develop new symptoms or need additional L3-4-level surgery within 5 years after surgery when compared to patients without preoperative L3-4 stenosis. These results indicate that prophylactic decompression for asymptomatic levels is unnecessary.

Lumbar Spinal Stenosis and Minimally Invasive Lumbar Decompression: A Narrative Review

Background

Lumbar spinal stenosis (LSS) is a common pain condition that causes lumbar back pain, radiating leg pain, and possible functional impairment. MILD is an emerging minimally invasive treatment for LSS. It is an image-guided percutaneous procedure designed to debulk hypertrophied ligamentum flavum. However, the exact short- and long-term efficacy, safety profile, indication criteria, and certain procedure details reported in medical literature vary.

Objective

This narrative review was to elucidate efficacy, safety profile, certain procedure details, advantages, and limitations of MILD.

Study Design

This is a narrative review.

Setting

All included articles are clinic trials including analytic studies and descriptive studies.

Methods

PubMed, Cochrane Library, and Scopus were searched. Only clinical trials of MILD procedure were included. Information of indications, contraindications, VAS scores, ODI scores, effective rate, efficacy durations, and certain procedure details was focused on.

Results

According to the literature, for the MILD procedure, the VAS score could be reduced from a pre-treatment level of 6.3-9.6 to a post-treatment level of 2.3-5.8. The ODI score could be reduced from a pre-treatment level of 38.8-55.3 to a post-treatment level of 27.4-39.8. The effective rate of the MILD procedure was reported to be 57.1%-88%. A 2-year postoperative stability of efficacy was also supported. One RCT study testified superior efficacy of MILD over epidural steroid injection.

Limitations

There is few high-quality literature in the review. Moreover, the long-term efficacy of MILD cannot be revealed according to the current literature.

Conclusion

Based on the reviewed literature, MILD is an effective and safe procedure. MILD can reduce pain intensity and improve functional status significantly. Therefore, it is a preferable option for LSS patients who failed conservative treatments, but not for those who require immediate invasive decompression surgery.

High prevalence of lumbar spinal stenosis in cases of idiopathic normal-pressure hydrocephalus affects improvements in gait disturbance after shunt operation

Objective

Idiopathic normal-pressure hydrocephalus (iNPH) is characterized by symptoms of dementia, urinary incontinence, and gait disturbance; however, gait disturbance tends to persist after shunt surgery. Gait disturbance and urinary dysfunction are also major symptoms of lumbar spinal stenosis (LSS). Currently, the epidemiology of the complications of LSS in iNPH is unclear. Here, we evaluated the coexistence rate of LSS in iNPH cases.

Methods

This was a retrospective case-control study. Between 2011 and 2017, 224 patients with a median age of 78 years, including 119 males, were diagnosed with iNPH and underwent lumboperitoneal shunts or ventriculoperitoneal shunts. LSS was diagnosed with magnetic resonance imaging by two spine surgeons. Age, sex, body mass index (BMI), Timed Up and Go (TUG) test, Mini Mental State Examination (MMSE) score, and urinary dysfunction were examined. We compared the changes in these variables in the group of patients with iNPH without LSS versus those with both iNPH and LSS.

Results

Seventy-three iNPH patients (32.6%) with LSS had significantly higher age and BMI. The existence of LSS did not alter the postoperative improvement rates of MMSE and urinary dysfunction; however, TUG improvement was significantly impaired in the LSS-positive group.

Conclusions

LSS affects improvements in gait disturbance of iNPH patients after shunt operation. Because our results revealed that one-third of iNPH patients were associated with LSS, gait disturbance observed in iNPH patients should be considered a potential complication of LSS.

A Change in Global Sagittal Alignment after Transforaminal Epidural Steroid Injections in Lumbar Spinal Stenosis

Patients' functional adaptation to pain can affect global sagittal alignment. This study evaluated the short-term spinal sagittal alignment change after transforaminal epidural steroid injection (TFESI) in lumbar spinal stenosis patients. Patients with lumbar spinal stenosis who underwent TFESI were retrospectively examined. Clinical outcomes were assessed using the Visual Analog Scale (VAS) and Oswestry Disability Index (ODI). Before and two weeks after the intervention, whole-spine lateral standing view radiographs were taken. Radiographic parameters including the Sagittal Vertical Axis (SVA), C2C7 Cobb, Thoracic Kyphosis (TK), Lumbar Lordosis (LL), Pelvic Incidence (PI), Pelvic Tilt (PT), Sacral Slope (SS), and Lumbopelvic Mismatch (PI-LL) were measured. Ninety-nine patients (mean age 64.3 ± 9.2 years) were included in this study. Both VAS and ODI outcomes were statistically improved after two weeks of intervention. Radiographic parameters showed that SVA, PT, and PI-LL mismatch were significantly decreased, while C2C7 Cobb, TK, SS, and LL were significantly increased after the intervention. SVA was improved by 29.81% (52.76 ± 52.22 mm to 37.03 ± 41.07 mm, p < 0.001). PT also decreased significantly from 28.71° ± 10.22° to 23.84° ± 9.96° (p < 0.001). Transforaminal epidural steroid injection (TFESI) significantly improves VAS, ODI, and global sagittal parameters in lumbar spinal stenosis patients.

Independent inter and intra-observer agreement of the Schizas's classification of degenerative lumbar stenosis: Comparison among three levels of surgical training

INTRODUCTION AND OBJECTIVES

Lumbar spinal stenosis is a common age-related condition that affects the quality of life. Multiple classifications have been developed to quantify the severity of stenosis affecting comparison between studies and homogenous communication among surgeons and researchers. Even though this classification has not shown a direct clinical correlation, Schizas's classification appears to be a simple method to assess stenosis. Our objective was to evaluate the inter and intraobserver independent agreement of the Schizas's classification to assess stenosis severity. Additionally, we aimed to compare agreement among three levels of training in spine surgery.

MATERIALS AND METHODS

An independent inter and intra observer agreement was conducted among junior, senior orthopedic residents and attending spine surgeons. Ninety lumbar levels from 30 patients were evaluated by 16 observers. Weighted kappa agreement was used.

RESULTS

Overall interobserver and intraobserver agreement was of 0.57 (95% CI=0.52-0.63) and 0.69 (0.55-0.79), respectively. Interobserver agreement according to level of training yielded values of 0.53 (0.46-0.60) for junior residents, 0.61 (0.54-0.67) for senior residents and 0.67 (0.59-0.74) for attendings. Intraobserver agreement was of 0.54 (0.48-0.60) for junior, 0.60 (0.55-0.66) for senior and 0.66 (0.60-0.72) for attendings.

CONCLUSION

The Schizas's classification showed moderate interobserver and substantial intraobserver agreement. Among attending surgeons, substantial inter and intraobserver agreement was observed. The classification allowed acceptable communication among trained spine surgeons.

Independent inter and intra-observer agreement of the Schizas's classification of degenerative lumbar stenosis: Comparison among three levels of surgical training

INTRODUCTION AND OBJECTIVES

Lumbar spinal stenosis is a common age-related condition that affects the quality of life. Multiple classifications have been developed to quantify the severity of stenosis affecting comparison between studies and homogenous communication among surgeons and researchers. Even though this classification has not shown a direct clinical correlation, Schizas's classification appears to be a simple method to assess stenosis. Our objective was to evaluate the inter and intraobserver independent agreement of the Schizas's classification to assess stenosis severity. Additionally, we aimed to compare agreement among three levels of training in spine surgery.

MATERIALS AND METHODS

An independent inter and intra observer agreement was conducted among junior, senior orthopedic residents and attending spine surgeons. Ninety lumbar levels from 30 patients were evaluated by 16 observers. Weighted kappa agreement was used.

RESULTS

Overall interobserver and intraobserver agreement was of 0.57 (95% CI=0.52-0.63) and 0.69 (0.55-0.79), respectively. Interobserver agreement according to level of training yielded values of 0.53 (0.46-0.60) for junior residents, 0.61 (0.54-0.67) for senior residents and 0.67 (0.59-0.74) for attendings. Intraobserver agreement was of 0.54 (0.48-0.60) for junior, 0.60 (0.55-0.66) for senior and 0.66 (0.60-0.72) for attendings.

CONCLUSION

The Schizas's classification showed moderate interobserver and substantial intraobserver agreement. Among attending surgeons, substantial inter and intraobserver agreement was observed. The classification allowed acceptable communication among trained spine surgeons.

Unilateral Modified Posterior Lumbar Interbody Fusion Combined With Contralateral Lamina Fenestration Treating Severe Lumbarspinal Stenosis: A Retrospective Clinical Study

Study design: Retrospective study. Objectives: The traditional PLIF is routinely utilized in severe lumbar spinal stenosis to relief the nerve compression. Nevertheless, the removal of posterior tension-band structure and the denervation and atrophy of the paraspinal muscle affect the clinical efficacy. Therefore, unilateral modified PLIF combined with contralateral fenestration was performed to overcome above-mentioned drawbacks. Methods: 32 modified PLIF and 33 traditional PLIF cases were retrospectively included. Operation time, length of stay (LOS) and blood loss were recorded. VAS of low back pain and leg pain, ODI and Sf-36 score including physical function and body pain were assessed. Fusion rate, lumbar lordosis (LL), intervertebral angle (IVA) and intervertebral height index (IHI) were evaluated radiologically. Results: Modified group possessed less blood loss, shorter operation time and less LOS. Compared with traditional group, the VAS of back pain was lower at 6 months postoperatively (P < .05) and the ODI score was lower at 3 months postoperatively (P < .05) in modified group. Modified group exhibited better physical function 3 months postoperatively and lower body pain 6 months postoperatively in Sf-36 score (P < .05). No statistic difference in LL, IVA, IHI and fusion rate were observed between both groups. Conclusions: Our modified PLIF combining with contralateral fenestration procedure exhibited particular advantages in comparison to traditional PLIF. The preservation of posterior tension-band structure facilitates to less low back pain, low complication rate and early functional recovery.

Small Preoperative Dural Sac Cross-Sectional Area and Anteriorly Placed Fusion Cages Are Risk Factors for Indirect Decompression Failure after Oblique Lateral Interbody Fusion

OBJECTIVE

1) To investigate if implant-related factors such as cage size and cage position are associated with radiologic improvement after indirect decompression with oblique lateral interbody fusion (OLIF). 2) To investigate the risk factors associated with indirect decompression failure (IDF) at the surgical levels after OLIF.

METHODS

From February 2015 to December 2019, 92 consecutive patients (188 levels) with lumbar spinal stenosis who underwent indirect decompression via OLIF with or without posterior instrumentation were studied retrospectively. Radiographic variables were measured preoperatively and postoperatively. The radiographic results were compared for cages with different heights and positions. IDF was defined as revision surgery within 6 months or persistent compressive symptoms 6 months after surgery.

RESULTS

Postoperative improvements were observed in all measured radiographic parameters except for segmental lordosis. Taller cages were associated with more shrinkage of the bulging disc and greater increase in dural sac diameter. Cages placed posteriorly showed larger postoperative subarticular diameters. Twelve patients (16 levels) had IDF. Multivariate logistic regression showed that after adjusting for age, sex, and body mass index, smaller preoperative dural sac cross-sectional area and anterior positioning of cages were both independent risk factors for IDF.

CONCLUSIONS

OLIF is an effective procedure for indirect decompression. To avoid reoperation for lumbar spinal stenosis, surgeons should aim to place the center of the cage at the posterior half of the lower endplate. Surgical levels with a preoperative dural sac cross-sectional area <44 mm2 may not be suitable for indirect decompression.

Radiological and functional assessment in patients with lumbar spinal stenosis

Background

Although patients with lumbar spinal stenosis (LSS) may have impaired postural control, current diagnosis of LSS depends mainly on clinical manifestation and radiological assessment, while functional assessment of postural balance remains less investigated. This study thus correlated radiological assessment via MR imaging with functional assessment using foam posturography in LSS patients.

Methods

Forty-seven LSS patients aged 50–85 years were enrolled. All patients received subjective outcome measures first, followed by plain radiography of whole spine and lumbosacral spine, MR imaging, and foam posturography under four conditions. Then, these results were analyzed using stepwise multiple regression analysis. Another 47 age- and sex-matched healthy controls also underwent foam posturography for comparison.

Results

The LSS group revealed significant increases in the sway area of foam posturography than the control group regardless of various conditions. Advanced age, poor walking endurance, and neural compression at the L2/3 level on MR images were significantly correlated with the characteristic parameters of foam posturography (p < 0.05). In contrast, subjectively reported pain and plain radiography did not correlate with posturographic results (p > 0.05).

Conclusions

Patients with LSS who exhibit less severe symptoms do not ensure normal postural balance. Functional assessment (foam posturography) on postural balance significantly correlated with radiological assessment (MR imaging) in LSS patients. The use of foam posturography may help assess postural control in LSS patients. It takes a short time and costs less, and would be practical to make this a routine examination in LSS patients.

High-resolution, three-dimensional magnetic resonance imaging axial load dynamic study improves diagnostics of the lumbar spine in clinical practice

BACKGROUND

The response to axial physiological pressure due to load transfer to the lumbar spine structures is among the various back pain mechanisms. Understanding the spine adaptation to cumulative compressive forces can influence the choice of personalized treatment strategies.

AIM

To analyze the impact of axial load on the spinal canal’s size, intervertebral foramina, ligamenta flava and lumbosacral alignment.

METHODS

We assessed 90 patients using three-dimensional isotropic magnetic resonance imaging acquisition in a supine position with or without applying an axial compression load. Anatomical structures were measured in the lumbosacral region from L1 to S1 in lying and axially-loaded magnetic resonance images. A paired t test at α = 0.05 was used to calculate the observed differences.

RESULTS

After axial loading, the dural sac area decreased significantly, by 5.2% on average (4.1%, 6.2%, P < 0.001). The intervertebral foramina decreased by 3.4% (2.7%, 4.1%, P < 0.001), except for L5-S1. Ligamenta flava increased by 3.8% (2.5%, 5.2%, P < 0.001), and the lumbosacral angle increased.

CONCLUSION

Axial load exacerbates the narrowing of the spinal canal and intervertebral foramina from L1-L2 to L4-L5. Cumulative compressive forces thicken ligamenta flava and exaggerate lumbar lordosis.

Influence of Spine Curvature on the Efficacy of Transcutaneous Lumbar Spinal Cord Stimulation

Transcutaneous spinal cord stimulation is a non-invasive method for neuromodulation of sensorimotor function. Its main mechanism of action results from the activation of afferent fibers in the posterior roots-the same structures as targeted by epidural stimulation. Here, we investigated the influence of sagittal spine alignment on the capacity of the surface-electrode-based stimulation to activate these neural structures. We evaluated electromyographic responses evoked in the lower limbs of ten healthy individuals during extension, flexion, and neutral alignment of the thoracolumbar spine. To control for position-specific effects, stimulation in these spine alignment conditions was performed in four different body positions. In comparison to neutral and extended spine alignment, flexion of the spine resulted in a strong reduction of the response amplitudes. There was no such effect on tibial-nerve evoked H reflexes. Further, there was a reduction of post-activation depression of the responses to transcutaneous spinal cord stimulation evoked in spinal flexion. Thus, afferent fibers were reliably activated with neutral and extended spine alignment. Spinal flexion, however, reduced the capacity of the stimulation to activate afferent fibers and led to the co-activation of motor fibers in the anterior roots. This change of action was due to biophysical rather than neurophysiological influences. We recommend applying transcutaneous spinal cord stimulation in body positions that allow individuals to maintain a neutral or extended spine.

Deep Learning Model for Automated Detection and Classification of Central Canal, Lateral Recess, and Neural Foraminal Stenosis at Lumbar Spine MRI

Background Assessment of lumbar spinal stenosis at MRI is repetitive and time consuming. Deep learning (DL) could improve -productivity and the consistency of reporting. Purpose To develop a DL model for automated detection and classification of lumbar central canal, lateral recess, and neural -foraminal stenosis. Materials and Methods In this retrospective study, lumbar spine MRI scans obtained from September 2015 to September 2018 were included. Studies of patients with spinal instrumentation or studies with suboptimal image quality, as well as postgadolinium studies and studies of patients with scoliosis, were excluded. Axial T2-weighted and sagittal T1-weighted images were used. Studies were split into an internal training set (80%), validation set (9%), and test set (11%). Training data were labeled by four radiologists using predefined gradings (normal, mild, moderate, and severe). A two-component DL model was developed. First, a convolutional neural network (CNN) was trained to detect the region of interest (ROI), with a second CNN for classification. An internal test set was labeled by a musculoskeletal radiologist with 31 years of experience (reference standard) and two subspecialist radiologists (radiologist 1: A.M., 5 years of experience; radiologist 2: J.T.P.D.H., 9 years of experience). DL model performance on an external test set was evaluated. Detection recall (in percentage), interrater agreement (Gwet κ), sensitivity, and specificity were calculated. Results Overall, 446 MRI lumbar spine studies were analyzed (446 patients; mean age ± standard deviation, 52 years ± 19; 240 women), with 396 patients in the training (80%) and validation (9%) sets and 50 (11%) in the internal test set. For internal testing, DL model and radiologist central canal recall were greater than 99%, with reduced neural foramina recall for the DL model (84.5%) and radiologist 1 (83.9%) compared with radiologist 2 (97.1%) (P < .001). For internal testing, dichotomous classification (normal or mild vs moderate or severe) showed almost-perfect agreement for both radiologists and the DL model, with respective κ values of 0.98, 0.98, and 0.96 for the central canal; 0.92, 0.95, and 0.92 for lateral recesses; and 0.94, 0.95, and 0.89 for neural foramina (P < .001). External testing with 100 MRI scans of lumbar spines showed almost perfect agreement for the DL model for dichotomous classification of all ROIs (κ, 0.95-0.96; P < .001). Conclusion A deep learning model showed comparable agreement with subspecialist radiologists for detection and classification of central canal and lateral recess stenosis, with slightly lower agreement for neural foraminal stenosis at lumbar spine MRI. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Hayashi in this issue.

Automatic lumbar spinal MRI image segmentation with a multi-scale attention network

Lumbar spinal stenosis (LSS) is a lumbar disease with a high incidence in recent years. Accurate segmentation of the vertebral body, lamina and dural sac is a key step in the diagnosis of LSS. This study presents an lumbar spine magnetic resonance imaging image segmentation method based on deep learning. In addition, we define the quantitative evaluation methods of two clinical indicators (that is the anteroposterior diameter of the spinal canal and the cross-sectional area of the dural sac) to assist LSS diagnosis. To improve the segmentation performance, a dual-branch multi-scale attention module is embedded into the network. It contains multi-scale feature extraction based on three 3 × 3 convolution operators and vital information selection based on attention mechanism. In the experiment, we used lumbar datasets from the spine surgery department of Shengjing Hospital of China Medical University to evaluate the effect of the method embedded the dual-branch multi-scale attention module. Compared with other state-of-the-art methods, the average dice similarity coefficient was improved from 0.9008 to 0.9252 and the average surface distance was decreased from 6.40 to 2.71 mm.

Predictability of the effects of epidural injection in lumbar spinal stenosis by assessment of lumbar MRI scans

BACKGROUND

Numerous classification systems have been proposed to interpret lumbar MRI scans. The clinical impact of the measured parameters remains unclear. To evaluate the clinical significance of imaging results in patients with multisegmental degenerative pathologies, treating specialists can perform image-guided local injections to target defined areas such as the epidural space.

OBJECTIVE

The aim of this retrospective study was to evaluate the correlation between lumbar spinal stenosis measurements obtained by MRI and improvement obtained through local epidural injection.

METHODS

In this retrospective study various measurement and classification systems for lumbar spinal stenosis were applied to MRI scans of 100 patients with this pathological condition. The reported effect of epidural bupivacaine/triamcinolone injections at the site was recorded in these patients and a comparative analysis performed.

RESULTS

MRI features assessed in this study did not show any relevant correlation with reported pain relief after epidural injection in patients with chronic lumbar stenosis, with the exception of posterior disc height with a weak Kendall's tau of -0.187 (p= 0.009).

CONCLUSIONS

Although MRI is crucial for evaluating lumbar spinal stenosis, it cannot replace but is rather complementary to a good patient history and clinical examination or the results of local diagnostic injections.

Occlusion of the lumbar spine canal during high-rate axial compression

BACKGROUND CONTEXT

While burst fracture is a well-known cause of spinal canal occlusion with dynamic, axial spinal compression, it is unclear how such loading mechanisms might cause occlusion without fracture.

PURPOSE

To determine how spinal canal occlusion during dynamic compression of the lumbar spine is differentially caused by fracture or mechanisms without fracture and to examine the influence of spinal level on occlusion.

STUDY DESIGN

A cadaveric biomechanical study.

METHODS

Twenty sets of three-vertebrae specimens from all spinal levels between T12 and S1 were subjected to dynamic compression using a hydraulic loading apparatus up to a peak velocity between 0.1 and 0.9 m/s. The presence of canal occlusion was measured optically with a high-speed camera. This was repeated with incremental increases of 4% compressive strain until a vertebral fracture was detected using acoustic emission measurements and computed tomographic imaging.

RESULTS

For axial compression without fracture, the peak occlusion (O_max) was 29.9±10.0%, which was deduced to be the result of posterior bulging of the intervertebral disc into the spinal canal. O_max correlated significantly with lumbar spinal level (p<.001), the compressive displacement (p<.001) and the cross-sectional area of the vertebra (p=.031).

CONCLUSIONS

Spinal canal occlusion observed without vertebral fracture involves intervertebral disc bulging. The lower lumbar spine tended to be more severely occluded than more proximal levels.

CLINICAL SIGNIFICANCE

Clinically, intermittent canal occlusion from disc bulging during dynamic compression may not show any radiographic features. The lower lumbar spine should be a focus of injury prevention intervention in cases of high-rate axial compression.

Minimally Invasive Pedicle Screw Fixation With Indirect Decompression by Ligamentotaxis in Pathological Fractures

BACKGROUND

The spine is the most common site of bony metastases. Associated pathological fractures can result in pain, neurological deficit, biomechanical instability, and deformity.

OBJECTIVE

To present a minimally invasive technique for indirect decompression by ligamentotaxis in pathological fractures.

METHODS

A minimally invasive approach was utilized to perform percutaneous pedicle screw fixation in patients who required stabilization for pathological fractures. Preoperative and postoperative computed tomography and magnetic resonance imaging were used to compare spinal canal area and midsagittal canal diameter.

RESULTS

Two patients with newly diagnosed pathological fractures underwent minimally invasive treatment. Each presented with minimal epidural disease and a chief complaint of intractable back pain without neurological deficit. They underwent minimally invasive pedicle screw fixation with indirect decompression by ligamentotaxis. In each case, postoperative imaging demonstrated an increase in spinal canal area and midsagittal canal diameter by an independent neuroradiologist. There were no perioperative complications, and each patient was neurologically stable without evidence of hardware failure at their 5- and 6-mo follow-up visits.

CONCLUSION

Minimally invasive percutaneous fixation can be used to stabilize pathological fractures and provide indirect decompression by ligamentotaxis. This procedure is associated with minimal blood loss, low morbidity, and rapid initiation of radiation therapy. Only patients with minimal epidural disease, stenosis caused primarily by bony retropulsion, and mild-to-moderate deformity should be considered candidates for this approach.

Degenerative Lumbar Spinal Stenosis

Degenerative lumbar spinal stenosis is the most frequent cause of low back pain and/or sciatica in the elderly patient. Epidemiology, pathophysiology, clinical manifestations and testing are reviewed in a wide current bibliographic investigation. The importance of the relationship between clinical presentation and imaging study, especially magnetic resonance imaging (MRI), is emphasized. Prior to treatment indication, it is necessary to identify the precise location of pain, as well as the differential diagnosis between neurological and vascular lameness. Conservative treatment combining medications with various physical therapy techniques solves the problem in most cases, while therapeutic testing with injections, whether epidural, foraminal or facetary, is performed when pain does not subside with conservative treatment and before surgery is indicated. Injections usually perform better results in relieving sciatica symptoms and less in neurological lameness. Equine tail and/or root decompression associated or not with fusion is the gold standard when surgical intervention is required. Fusion after decompression is necessary in cases with segmental instability, such as degenerative spondylolisthesis. When canal stenosis occurs at multiple levels and is accompanied by axis deviation, whether coronal and/or sagittal, correction of axis deviations should be performed in addition to decompression and fusion, especially of the sagittal axis, in which a lumbar lordosis correction is required with techniques that correct the rectified lordosis to values close to the pelvic incidence.

A new interspinous process distraction device BacFuse in the treatment of lumbar spinal stenosis with 5 years follow-up study

To explore a suitable indication of interspinous process distraction device for lumbar spinal stenosis with BacFuse.Patients of lumbar spinal stenosis (LSS) who experienced interspinous process distraction device surgery with BacFuse from June 2014 to January 2015 in our institute were included. We classified LSS into central and lateral types, and then divided these into severe and moderate according to the degree of stenosis. Each type was divided into 2 groups. Patients in group A underwent distraction without bone decompression (stand-alone), while patients in group B underwent bone decompression combined with distraction. Follow-up was performed at 1 month, 3 months, 6 months, 2 years, and 5 years after surgery. Zurich Claudication Questionnaire (ZCQ) was recorded to assess the patient's postoperative condition at each follow-up.A total of 142 patients were available for follow up at each time interval. There was a significant difference between the preoperative and final follow-up ZCQ scores for every LSS type. In addition, there was no difference between group A and group B in the postoperative ZCQ scores with the exception of the lateral severe type. In the study, 22 of the 23 patients (95.65%) in the lateral moderate type were considered to have a satisfactory result in group B, with a similar result of 93.33% (14/15) in group A (P = .75). In the lateral severe type, the patient satisfaction rate was 65.22% (15/23) and 90.63% (29/32) in group A and group B (P = .02), respectively. In the central moderate type, the patient satisfaction rate was 81.82% (15/23) and 76.92% (10/13) in group A and group B (P = .77), respectively. Satisfaction rate for the follow-up results in the central severe type reached 57.14% (4/7) in group A, and 54.55% (6/11) in group B (P = .91). Moreover, no relationship was found between satisfaction and neurogenic intermittent claudication.The most suitable indication for BacFuse treatment was the lateral moderate type. For lateral severe patients, distraction combined with decompression is suggested for a higher satisfaction rate. Severe central spinal stenosis was shown to be a relative contraindication for BacFuse.

The Impact of Age on the Outcomes of Minimally Invasive Lumbar Decompression for Lumbar Spinal Stenosis

Background and Purpose

Minimally invasive lumbar decompression (mild^®) is an effective long-term therapy for patients with symptomatic lumbar spinal stenosis (LSS) resulting primarily from hypertrophic ligamentum flavum (HLF). Most subjects in clinical studies of the mild procedure have been older adults (age≥65). While the incidence of LSS increases with age, a substantial number of adults (age<65) also suffer from neurogenic claudication secondary to HLF. In this report, outcomes of mild were compared between adults and older adults.

Patients and Methods

All prospective studies of the mild procedure with a 1-year follow-up completed since the beginning of 2012 that allowed the inclusion of adult patients of all ages were reviewed. Outcomes of visual analog scale (VAS), Oswestry Disability Index (ODI), Pain Disability Index (PDI), Roland Morris Low Back Pain and Disability Questionnaire (RMQ), standing time and walking distance were compared for adults and older adults.

Results

Four studies met the inclusion criteria, resulting in an analysis of 49 adults and 160 older adults. Patients in both age groups experienced significant mean improvements in all but one outcome measure at 6- and 12-month follow-up. Differences between the two age groups in all scores at 6 and 12 months were not statistically significant.

Conclusion

Analysis of the four studies indicated that symptom improvements for adults and older adults were significant from baseline, and no statistically significant difference was observed between the two age groups. These results illustrate that mild can be an effective treatment for LSS due primarily to HLF, regardless of the adult patient age.

Relationship between the location of ligamentum flavum hypertrophy and its stress in finite element analysis

Objective

To quantitatively describe the stress of the ligamentum flavum (LF) using the finite element method and to compare the stress at different parts of the healthy LF.

Methods

Based on the high resolution computed tomography imaging data of a healthy 22‐year‐old man, three‐dimensional nonlinear L_4–5 lumbar finite element model (FEM) representing intact condition was developed. The LF, as the object of the present research, was incorporated into the spinal model in the form of solid three‐dimensional structure. The model’s validity is verified by comparing its biomechanical indices, such as range of motion and axial compression pressure displacement, with published results under specific loading conditions. To authenticate the accuracy of the solid LF, the lamina attachments, the central cross‐section, and other anatomy indicators were compared with figures in the published literature. After the average and maximum von Mises stress on the surface of LF under various working conditions were measured using ANSYS and AutoCAD software, the surface stress difference in the LF between the ventral and dorsal sides as well as the lateral and lamina parts were determined.

Results

The FEM predicted a similar tendency for biomechanical indices as shown in previous studies. The lamina attachments, the central cross‐section, and the height as well as the width of the LF in the healthy FEM were in accordance with published results. In the healthy model, the average and maximum von Mises stress in the shallow layer of the LF were, respectively, 1.40, 2.28, 1.76, 1.48, 1.38 and 1.79, 2.41, 1.46, 1.42, 1.71 times that in the deep layer under a compressive preload of 500 N incorporated with flexion, extension, and lateral and rotational moments (10 Nm). The most conspicuous difference in surface stress was observed with the flexion motion, with a nearly 241% difference in the maximum stress and a 228% difference in the average stress compared to those in other states. As far as the whole dorsal side of the LF was concerned, the maximum surface stress was almost all concentrated in the dorsal neighboring facet joint portion. In addition, the maximum and average stress were, respectively, 77%, 72%, 15%, 11%, 71% and 153%, 39%, 54%, 200%, 212% higher in the lateral part than in the lamina part.

Conclusion

Based on the predisposition of LF hypertrophy in the human spine and the stress distribution of this study, the positive correlation between LF hypertrophy and its stress was confirmed.

A Review of Lumbar Spinal Stenosis with Intermittent Neurogenic Claudication: Disease and Diagnosis

Objective

Lumbar spinal stenosis (LSS) is a degenerative spinal condition affecting nearly 50% of patients presenting with lower back pain. The goal of this review is to present and summarize the current data on how LSS presents in various populations, how it is diagnosed, and current therapeutic strategies. Properly understanding the prevalence, presentation, and treatment options for individuals suffering from LSS is critical to providing patients the best possible care.

Results

The occurrence of LSS is associated with advanced age. In elderly patients, LSS can be challenging to identify due to the wide variety of presentation subtleties and common comorbidities such as degenerative disc disease. Recent developments in imaging techniques can be useful in accurately identifying the precise location of the spinal compression. Treatment options can range from conservative to surgical, with the latter being reserved for when patients have neurological compromise or conservative measures have failed. Once warranted, there are several surgical techniques at the physician’s disposal to best treat each individual case.

Biomechanics and Mechanism of Action of Indirect Lumbar Decompression and the Evolution of a Stand-alone Spinous Process Spacer

Objective

Objective Interspinous process spacers are used in the treatment of lumbar spinal stenosis by preventing extension at the implanted level and reducing claudication, which is a common symptom of lumbar spinal stenosis. This review assessed the current safety and performance of lumbar spinal stenosis treatments and the biomechanical effects of spinal position, range of motion, and the use of interspinous process spacers.

Method

Method EMBASE and PubMed were searched to find studies reporting on the safety and performance of nonsurgical treatment, including physical therapy and pharmacological treatment, and surgical treatment, including direct and indirect lumbar decompression treatment. Results were supplemented with manual searches to include studies reporting on the use of interspinous process spacers and the review of biomechanical testing performed on the Superion device.

Results

Results The effects of spinal position in extension and flexion have been shown to have an impact in the variation in dimensions of the spinal canal and foramina areas. Overall studies have shown that spinal positions from flexion to extension reduce the spinal canal and foramina dimensions and increase ligamentum flavum thickness. Biomechanical test data have shown that the Superion device resists extension and reduces angular movement at the implantation level and provides significant segmental stability.

Conclusions

Conclusions Superion interspinous lumbar decompression is a minimally invasive, low-risk procedure for the treatment of lumbar spinal stenosis, which has been shown to have a low safety profile by maintaining sagittal alignment, limiting the potential for device dislodgment or migration, and to preserve mobility and structural elements.

Unfolding the outcomes of surgical treatment of lumbar spinal stenosis—a prospective 5- and 10-year follow-up study

Purpose

In this prospective study, we aim to determine surgical outcomes in patients with lumbar spinal stenosis (LSS) 10 years after surgery.

Methods

The study population consisted of 96 LSS patients who underwent decompressive surgery, 72 of whom participated in the 10-year follow-up. The patients completed a questionnaire preoperatively and 3 months, 5 years, and 10 years postoperatively. Outcome measures were satisfaction with the surgical outcomes, the Oswestry Disability Index (ODI), the visual analog scale (VAS), the numeric rating scale (NRS-11), and walking ability quantified in meters. Postoperative improvements at 5 and 10 years were analyzed using linear mixed models. Furthermore, comparisons between postoperative time points were made for clinical courses of pain, disability, and walking ability.

Results

At the 10-year follow-up, 68% of the patients were satisfied with the surgical outcomes. All the measured outcomes showed statistically significant improvement from baseline to the 5- and 10-year follow-up. The mean VAS score was 9.8 mm higher at the 5-year follow-up and 7.8 mm at the 10-year follow-up compared to the 3-month follow-up point. Similarly, the mean ODI was 4.8% higher at the 10-year follow-up compared to the 3-month follow-up point.

Conclusion

This study reports the clinical course of pain, disability, and walking distance after LSS surgery with the 10-year follow-up. Based on our study results, patients with LSS could expect to have positive effects of their back surgery up to 10 years. However, minor worsening in pain and disability may occur and one-fourth of the patients may need a reoperation during the 10-year follow-up period.

Comparative Study Between Uniportal Full-Endoscopic Interlaminar and Tubular Approach in the Treatment of Lumbar Spinal Stenosis: A Pilot Study

STUDY DESIGN

Multicenter, prospective, randomized, and double-blinded study.

OBJECTIVES

To compare tubular and endoscopic interlaminar approach.

METHODS

Patients with lumbar spinal stenosis and neurogenic claudication of were randomized to tubular or endoscopic technique. Enrollment period was 12 months. Clinical follow up at 1, 3, 6 months after surgery with visual analogue scale (VAS), Oswestry Disability Index (ODI), and Japanese Orthopedic Association (JOA) score. Radiologic evaluation with magnetic resonance pre- and postsurgery.

RESULTS

Twenty patients were enrolled: 10 in tubular approach (12 levels) and 10 in endoscopic approach (11 levels). The percentage of enlargement of the spinal canal was higher in endoscopic approach (202%) compared with tubular approach (189%) but was not statistically significant (P = .777). The enlargement of the dural sac was higher in endoscopic group (209%) compared with tubular group (203%) but no difference was found between the 2 groups (P = .628). A modest significant correlation was found between the percentage of spinal canal decompression and enlargement of the dural sac (r = 0.5, P = .023). Both groups reported a significant clinical improvement postsurgery. However, no significant association was found between the percentage of enlargement of the spinal canal or the dural sac and clinical improvement as determined by scales scores. Endoscopic group had lower intrasurgical bleeding (P < .001) and lower disability at 6 months of follow-up than tubular group (p=0.037).

CONCLUSIONS

In the treatment of lumbar spinal stenosis, endoscopic technique allows similar decompression of the spinal canal and the dural sac, lower intrasurgical bleeding, similar symptoms improvement, and lower disability at 6 months of follow-up, as compared with the tubular technique.

Could automated machine-learned MRI grading aid epidemiological studies of lumbar spinal stenosis? Validation within the Wakayama spine study

BACKGROUND

MRI scanning has revolutionized the clinical diagnosis of lumbar spinal stenosis (LSS). However, there is currently no consensus as to how best to classify MRI findings which has hampered the development of robust longitudinal epidemiological studies of the condition. We developed and tested an automated system for grading lumbar spine MRI scans for central LSS for use in epidemiological research.

METHODS

Using MRI scans from the large population-based cohort study (the Wakayama Spine Study), all graded by a spinal surgeon, we trained an automated system to grade central LSS in four gradings of the bone and soft tissue margins: none, mild, moderate, severe. Subsequently, we tested the automated grading against the independent readings of our observer in a test set to investigate reliability and agreement.

RESULTS

Complete axial views were available for 4855 lumbar intervertebral levels from 971 participants. The machine used 4365 axial views to learn (training set) and graded the remaining 490 axial views (testing set). The agreement rate for gradings was 65.7% (322/490) and the reliability (Lin's correlation coefficient) was 0.73. In 2.2% of scans (11/490) there was a difference in classification of 2 and in only 0.2% (1/490) was there a difference of 3. When classified into 2 groups as 'severe' vs 'no/mild/moderate'. The agreement rate was 94.1% (461/490) with a kappa of 0.75.

CONCLUSIONS

This study showed that an automated system can "learn" to grade central LSS with excellent performance against the reference standard. Thus SpineNet offers potential to grade LSS in large-scale epidemiological studies involving a high volume of MRI spine data with a high level of consistency and objectivity.

Interobserver Reliability When Classifying MR Imaging of the Lumbar Spine: Written Instructions Alone Do Not Suffice

PURPOSE

Numerous classification systems have been proposed to analyze lumbar spine MRI scans. When evaluating these systems, most studies draw their conclusions from measurements of experienced clinicians. The aim of this study was to evaluate the impact of specific measurement training on interobserver reliability in MRI classification of the lumbar spine.

METHODS

Various measurement and classification systems were assessed for their interobserver reliability in 30 MRIs from patients with chronic lumbar back and sciatic pain. Two observers were experienced spine surgeons. The third observer was an inexperienced medical student who, prior to the study measurements, in addition to being given the detailed written instructions also given to the surgeons, obtained a list of 20 reference measurements in MRI scans from other patients to practice with.

RESULTS

Excellent agreement was observed between the medical student and the spine surgeon who had also created the reference measurements. Between the two spine surgeons, agreement was markedly lower in all systems investigated (e.g., antero-posterior spinal canal diameter intraclass correlation coefficient [ICC] [3.1] = 0.979 vs. ICC [3.1] = 0.857).

CONCLUSION

These data warrant the creation of publicly available standardised measurement examples of accepted classification systems to increase reliability of the interpretation of MR images.

NATURAL HISTORY OF LUMBAR CANAL STENOSIS: CLINICAL ASPECTS AND SAGITTAL BALANCE

ABSTRACT Objective To compare the sagittal alignment (SA) parameters in individuals with LCS and surgical indication with a control group and to study the correlations between SA parameters and ODI, VAS and EQ-5D in individuals with LCS and surgical indication. Methods In this multicenter cross-sectional case-control study, the individuals were allocated as follows. A stenosis group (SG) composed by patients with LCS confirmed by magnetic resonance imaging with surgical indication, treated between July 2010 and August 2016 and a control group (CG), without LCS. All subjects underwent anamnesis, completed the Health-related Quality of Life (HRQoL) and total spine radiographs were taken. Clinical data, HRQoL and radiographic parameters were correlated. Results Sixty-four individuals formed the SG and 14 the CG. The SG had higher values of mean age, coronal imbalance, sagittal vertical axis (SVA), pelvic tilt (PT), sacrofemoral distance (SFD), overhang (OH), PI-LL mismatch, Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) for pain and smaller thoracic kyphosis (TK), total (TLPL) and regional lumbopelvic lordosis (RLPL) in all vertebrae, sagittal offset (SO) in all evaluated vertebrae and EuroQol-5D (EQ-5D) with p <0.05. In the SG, the only significant correlations (p <0.05) were between TK and ODI and EQ-5D; all the other sagittal parameters did not correlated with VAS, ODI or EQ-5D. Conclusion SG had SA parameters altered in relation to CG. There was a direct correlation between decrease in TK and worsening of ODI and EQ-5D in SG. Level of evidence: III; Case Control Study.

Toward a cure for lumbar spinal stenosis: The potential of interspinous process decompression

There is a growing impetus to treat aging as a disease in the quest to significantly extend the human life span through cellular regeneration methods. This approach, while promising, overlooks the fact that the evolutionary adaptation to bipedalism puts the human body in a distinctively vulnerable biomechanical and functional position. Orthograde human posture places unusually-high axial compressive loads on the weight-bearing joints of the skeleton, resulting in arthritic deterioration with aging. The effects are particularly robust in the lumbar spine were age-related degeneration, most commonly lumbar spinal stenosis (LSS), is ubiquitous among the elderly. It is postulated that re-establishing a favorable mechanical environment via interventions that unload the affected spinal joint complex may mitigate and potentially reverse the structural damage that is the cardinal pathoanatomical feature of this disease. The hypothesis of this paper is that a minimally-invasive surgical procedure, interspinous process decompression (IPD), which utilizes a stand-alone intervertebral spacer, effectively unloads the diseased spinal motion segment providing a healthy micro-environment to reverse and repair age-related and genetic deterioration of the spinal motion segment. Several lines of supporting evidence are provided from long-term follow-up results of a randomized controlled trial of IPD safety and effectiveness of the Superion® device including clinical outcomes, reoperation rates, opioid analgesic usage and advanced imaging utilization. All of these outcomes show uniquely-favorable trends with time that imply that the benefits of IPD are structural. The compendium of evidence suggests that IPD offers both a durable palliative effect due to direct blocking of back extension and a disease-modifying effect due to unloading of the spinal joint complex.

Is Lumbosacral Transitional Vertebra Associated with Degenerative Lumbar Spinal Stenosis?

The aim of this study was to shed light on the association between lumbosacral transitional vertebra (LSTV) and degenerative lumbar spinal stenosis (DLSS). A cross-sectional retrospective study was performed on 165 individuals that were diagnosed with clinical picture of DLSS (age range: 40-88 years; sex ratio: 80M/85F) and 180 individuals without DLSS related symptoms (age range: 40-99 years; sex ratio: 90M/90F). All participants had undergone high-resolution CT scan for the lumbar region in the same position. We also used the volume rendering method to obtain three-dimensional CT images of the lumbosacral area. Both males and females in the stenosis group manifest greater prevalence of LSTV than their counterparts in the control group (P<0.001). Furthermore, the presence of LSTV increases the likelihood of degenerative spinal stenosis (odds ratio= 3.741, P<0.001). In the control group, LSTV was more common in males, and sacral slope angle of males was significantly greater in LSTV group compared to non-LSTV. This study indicates that LSTV was significantly associated with symptomatic DLSS.

Magnitude of dural tube compression does not show a predictive value for symptomatic lumbar spinal stenosis for 1-year follow-up: a prospective cohort study in the community

Background

The North American Spine Society states that lumbar spinal stenosis (LSS) is a clinical syndrome, and there is insufficient evidence to make a recommendation for or against a correlation between clinical symptoms or function and the presence of anatomic narrowing of the spinal canal on MRI. The main purpose of this study was to assess the influence of the magnitude of dural tube compression on MRI on LSS symptoms at the cross-sectional and 1-year follow-up.

Methods

This was a prospective cohort study of 459 participants who were assessed for LSS using a questionnaire and conventional MRI of the lumbar spine. After 1 year, 335 subjects (follow-up rate 73.0%) were assessed for LSS using the same questionnaire. The time course of the clinical subjective symptoms of LSS and the relationship between the said symptoms of LSS and magnitude of dural tube compression on MRI were analyzed in a cross-sectional and longitudinal fashion.

Results

1) The dural sac cross-sectional area (DCSA) decreased with age. 2) Severe dural tube compression had a strong influence on the presence of symptomatic LSS; however, 40%–70% of participants with severe dural tube compression did not show clinical symptoms of LSS. 3) At the 1-year follow-up, >50% of the LSS-positive participants in the initial year were reclassified as LSS negative, and 10% of the LSS-negative participants were reclassified as LSS positive. 4) The magnitude of the DCSA on MRI did not directly affect the presence of LSS at the 1-year follow-up.

Conclusion

LSS symptoms were changeable. Anatomical dural tube compression on MRI did not predict the presence of clinical LSS symptoms at the 1-year follow-up.

The Utility of Preoperative Magnetic Resonance Imaging for Determining the Flexibility of Sagittal Imbalance

BACKGROUND

Scoliosis X-rays are the gold standard for assessing preoperative lumbar lordosis; however, particularly for flexible lumbar deformities, it is difficult to predict from these images the extent of correction required, as standing radiographs cannot predict the thoracolumbar alignment after intraoperative positioning.

OBJECTIVE

To determine the utility of preoperative MRI in surgical planning for patients with flexible sagittal imbalance.

METHODS

We identified 138 patients with sagittal imbalance. Radiographic parameters including pelvic incidence and lumbar lordosis were obtained from images preoperatively.

RESULTS

The mean difference was 2.9° between the lumbar lordosis measured on supine MRI as compared to the intraoperative X-rays, as opposed to 5.53° between standing X-rays and intraoperative X-ray. In patients with flexible deformities (n = 24), the lumbar lordosis on MRI measured a discrepancy of 3.08°, as compared to a discrepancy of 11.46° when measured with standing X-ray.

CONCLUSION

MRI adequately determined which sagittal deformities were flexible. Furthermore, with flexible sagittal deformities, lumbar lordosis measured on MRI more accurately predicted the intraoperative lumbar lordosis than that measured on standing X-ray. The ability to preoperatively predict intraoperative lumbar lordosis with positioning helps with surgical planning and patient counseling regarding expectations and risks of surgery.

Correlation of listhesis on upright radiographs and central lumbar spinal canal stenosis on supine MRI: is it possible to predict lumbar spinal canal stenosis?

OBJECTIVE

To investigate whether upright radiographs can predict lumbar spinal canal stenosis using supine lumbar magnetic resonance imaging (MRI) and to investigate the detection performance for spondylolisthesis on upright radiographs compared with supine MRI in patients with suspected lumbar spinal canal stenosis (LSS).

MATERIALS AND METHODS

In this retrospective study, conventional radiographs and MR images of 143 consecutive patients with suspected LSS (75 female, mean age 72 years) were evaluated. The presence and extent of listhesis (median ± interquartile range) were assessed on upright radiographs and supine MRI of L4/5. In addition, the grade of central spinal stenosis of the same level was evaluated on MRI according to the classification of Schizas and correlated with the severity/grading of anterolisthesis on radiographs.

RESULTS

Anterolisthesis was detected in significantly more patients on radiographs (n = 54; 38%) compared with MRI (n = 28; 20%), p < 0.001. Pairwise comparison demonstrated a significantly larger extent of anterolisthesis on radiographs (9 ± 5 mm) compared with MRI (5 ± 3 mm), p < 0.001. A positive correlation was found regarding the extent of anterolisthesis measured on radiographs and the grade of stenosis on MRI (r = 0.563, p < 0.001). Applying a cutoff value of ≥5 mm anterolisthesis on radiographs results in a specificity of 90% and a positive predictive value of 78% for the detection of patients with LSS, as defined by the Schizas classification.

CONCLUSION

Upright radiographs demonstrated more and larger extents of anterolisthesis compared with supine MRI. In addition, in patients with suspected LSS, the extent of anterolisthesis on radiographs (particularly ≥5 mm) is indicative of LSS and warrants lumbar spine MRI.

Preoperative Assessment of Neural Elements in Lumbar Spinal Stenosis by Upright Magnetic Resonance Imaging: An Implication for Routine Practice?

Introduction

Lumbar spinal stenosis (LSS) is a kinetic-dependent disease typically aggravating during spinal loading. To date, assessment of LSS is usually performed with magnetic resonance imaging (MRI). However, conventional supine MRI is associated with significant drawbacks as it does not truly reflect physiological loads, experienced by discoligamentous structures during erect posture. Consequently, supine MRI often fails to reveal the source of pain and/or disability caused by LSS.

The present study sought to assess neural dimensions via MRI in supine, upright, and upright-hyperlordotic position in order to evaluate the impact of patient positioning on neural narrowing. Therefore, radiological measures such as neuroforaminal dimensions, central canal volume, sagittal listhesis, and lumbar lordosis at spinal level L4/5 were extracted and stratified according to patient posture.

Materials and methods

Overall, 10 subjects were enclosed in this experimental study. MRI was performed in three different positions: (1) 0° supine (SP), (2) 80° upright (UP), and (3) 80° upright + hyperlordotic (HY) posture. Upright MRI was conducted utilizing a 0.25T open-configuration scanner equipped with a rotatable examination bed allowing for true standing MRI. Radiographic outcome of upright MRI imaging was extracted and evaluated according to patient positioning.

Results

Upright MRI-based assessment of neural dimensions was successfully accomplished in all subjects. Overall, radiographic parameters revealed a significant decrease of neural dimensions from supine to upright position: Specifically, mean foraminal area decreased from SP to UP by 13.3% (P ≤ 0.05) as well as from SP to HY position by 21% (P ≤ 0.05). Supplementation of hyperlordosis did not result in additional narrowing of neural elements (P ≥ 0.05). Furthermore, central canal volume revealed a decrease of 7% at HY and 8% at UP compared to SP position (P ≥ 0.05). Assessment of lumbar lordosis yielded in a significant increase when assessed at HY (+22.1%) or UP (+8.7%) compared to SP (P ≤ 0.05).

Conclusions

Our data suggest that neuroforaminal dimensions assessed by conventional supine MRI are potentially overestimated in patients with LSS. Especially, in patients having occult disease not visualized on conventional imaging modalities, upright MRI allows for a precise, clinically relevant, and at the same time non-invasive evaluation of neural elements in LSS when neural decompression is considered.

Improvement in Sagittal Balance After Decompression Surgery without Fusion in Patients with Degenerative Lumbar Stenosis: Clinical and Radiographic Results at 1 Year

OBJECTIVE

To evaluate modifications in static spinal status after posterior decompression surgery without fusion in patients with symptomatic central canal stenosis.

METHODS

From November 2014 to May 2016, 72 patients who underwent isolated decompression for lumbar spinal stenosis were enrolled prospectively in this single-center study. All of the patients had lateral full-body x-ray scans with the EOS system (EOS Imaging, Paris, France) before surgery and after 12 months of follow-up. Patients were classified into 3 groups according to their preoperative sagittal vertical axis (<50 mm, ≥50 mm, and <100 mm, ≥100 mm).

RESULTS

SVA decreased significantly (SVA preoperative: 72.3 ± 43.1; SVA postoperative: 48.3 ± 46.8. P < 0.001). Lumbar lordosis increased significantly from 41.9 ± 13.4 in the preoperative period to 46.5 ± 14.8 at the last follow-up (P < 0.001). In the imbalance groups, the mean postoperative SVA decreased significantly compared with preoperative SVA (P = 0.004). Surgery led to a significant increase in lumbar lordosis in the 3 groups (P < 0.05). Nonetheless, a certain degree of residual imbalance persisted in the major imbalance group. In all of the groups, decompression surgery led to a significant improvement in clinical scores (P < 0.05).

CONCLUSIONS

Our study showed an improvement in sagittal balance and lumbar lordosis after decompression surgery without fusion, even in patients with a preoperative SVA >100 mm. However, a certain degree of sagittal imbalance may persist after surgery in patients with major initial imbalance (SVA >100 mm). Nonetheless, after surgery, these patients experienced a clinical benefit comparable with that in the other groups.

Lumbar spinal stenosis: symptoms, diagnosis and treatment (meta-analysis of literature data)

Lumbar spinal stenosis is a disease in which degenerated discs, ligamentum flavum, facet joints, while aging, lead to a narrowing of the space around the neurovascular structures of the spine. This article presents a meta-analysis of literature data on epidemiology, causes, pathogenesis, diagnosis and various types of treatment of lumbar spinal stenosis.

Characteristics and determinants of clinical symptoms in radiographic lumbar spinal stenosis in a tertiary health care centre in sub-Saharan Africa

BACKGROUND

Lumbar spinal stenosis (LSS) refers to narrowing of the lumbar central spinal canal, lateral recess, and/or neuro-foramina. Radiographic LSS plays an important role in clinical LSS but is not solely accountable for the presence of symptoms. We sought to characterise clinical LSS and to determine factors associated with presence of symptoms of LSS in patients with radiographic LSS in a sub Saharan Africa setting.

METHODS

After prior ethical clearance, a case control study was done in a tertiary hospital in Douala-Cameroon, including 105 patients with radiographic LSS: 57 with symptoms of LSS (cases) and 58 with no symptoms (controls). Spinal stenosis was assessed using computed tomography (CT) scans. Data were analysed using SPSS version 23.

RESULTS

The mean age of our study participants was 53.4 ± 13.1 years. The mean age of onset of symptoms of LSS was 50.3 ± 11.6 years and the most common symptoms were Low back pain (100.0%), radicular symptoms (98.2%) and neurogenic claudication (98.2%). Obesity (p < 0.001) and a high waist circumference (p = 0.002) were significantly associated with presence of LSS symptoms in persons with radiographic LSS. After adjusting for body mass index, a positive family history of low back pain (p = 0.004), vertebra lesion at L2 (p = 0.034), L3 (p = 0.002), L4 (p = 0.025) and multiple (p = 0.008) levels, degenerative disc protrusion (p = 0.044), disc lesion at L3-L4 (p = 0.001), L4-L5 (p = 0.011) and multiple (p = 0.046) levels were significantly associated with presence of symptoms of LSS in persons with radiographic LSS.

CONCLUSION

Characteristics of clinical LSS have been described in this sub-Saharan Africa population. Obesity, a high waist circumference and a positive family history of low back pain are significantly associated with presence of symptoms of LSS in persons with radiographic LSS.

Predictability of the effects of facet joint infiltration in the degenerate lumbar spine when assessing MRI scans

Background

Imaging results are frequently considered as hallmarks of disease by spine surgeons to plan their future treatment strategy. Numerous classification systems have been proposed to quantify or grade lumbar magnetic resonance imaging (MRI) scans and thus objectify imaging findings. The clinical impact of the measured parameters remains, however, unclear. To evaluate the pathological significance of imaging findings in patients with multisegmental degenerative findings, clinicians can perform image-guided local infiltrations to target defined areas such as the facet joints.

The aim of the present retrospective study was to evaluate the correlation of MRI facet joint degeneration and spinal stenosis measurements with improvement obtained by image-guided intraarticular facet joint infiltration.

Methods

Fifty MRI scans of patients with chronic lumbar back pain were graded radiologically using a wide range of classification and measurement systems. The reported effect of facet joint injections at the site was recorded, and a comparative analysis performed.

Results

When we allocated patients according to their reported pain relief, 27 showed no improvement (0–30%), 16 reported good improvement (31–75%) and 7 reported excellent improvement (> 75%). MRI features assessed in this study did, however, not show any relevant correlation with reported pain after facet joint infiltration: Values for Kendall’s tau ranged from τ = − 0.190 for neuroforaminal stenosis grading as suggested by Lee, to τ = 0.133 for posterior disc height as proposed by Hasegawa.

Conclusion

Despite the trend in evidence-based medicine to provide medical algorithms, our findings underline the continuing need for individualised spine care that, along with imaging techniques or targeted infiltrations, includes diagnostic dimensions such as good patient history and clinical examination to formulate a diagnosis.

Trial registration

ClinicalTrials.gov, NCT03308149, retrospectively registered October 2017

Electronic supplementary material

The online version of this article (10.1186/s13018-017-0685-x) contains supplementary material, which is available to authorized users.

A novel diagnostic parameter, foraminal stenotic ratio using three-dimensional magnetic resonance imaging, as a discriminator for surgery in symptomatic lumbar foraminal stenosis

BACKGROUND CONTEXT

No previous studies have reported the radiological features of patients requiring surgery in symptomatic lumbar foraminal stenosis (LFS).

PURPOSE

This study aims to investigate the diagnostic accuracy of a novel technique, foraminal stenotic ratio (FSR), using three-dimensional magnetic resonance imaging for LFS at L5-S by comparing patients requiring surgery, patients with successful conservative treatment, and asymptomatic patients.

STUDY DESIGN

This is a retrospective radiological comparative study.

PATIENT SAMPLE

We assessed the magnetic resonance imaging (MRI) results of 84 patients (168 L5-S foramina) aged ≥40 years without L4-L5 lumbar spinal stenosis. The foramina were divided into three groups following standardized treatment: stenosis requiring surgery (20 foramina), stenosis with successful conservative treatment (26 foramina), and asymptomatic stenotic foramen (122 foramina).

OUTCOME MEASURES

Foraminal stenotic ratio was defined as the ratio of the length of the stenosis to the length of the foramen on the reconstructed oblique coronal image, referring to perineural fat obliterations in whole oblique sagittal images. We also evaluated the foraminal nerve angle and the minimum nerve diameter on reconstructed images, and the Lee classification on conventional T1 images.

MATERIALS AND METHODS

The differences in each MRI parameter between the groups were investigated. To predict which patients require surgery, receiver operating characteristic (ROC) curves were plotted after calculating the area under the ROC curve.

RESULTS

The FSR showed a stepwise increase when comparing asymptomatic, conservative, and surgical groups (mean, 8.6%, 38.5%, 54.9%, respectively). Only FSR was significantly different between the surgical and conservative groups (p=.002), whereas all parameters were significantly different comparing the symptomatic and asymptomatic groups. The ROC curve showed that the area under the curve for FSR was 0.742, and the optimal cutoff value for FSR for predicting a surgical requirement in symptomatic patients was 50% (sensitivity, 75%; specificity, 80.7%).

CONCLUSIONS

The FSR determined LFS requiring surgery among symptomatic patients, with moderate accuracy. Foramina occupied ≥50% by fat obliteration were likely to fail conservative treatment, with a positive predictive value of 75%.

Pelvic retroversion: a compensatory mechanism for lumbar stenosis

OBJECTIVE

The flexed posture of the proximal (L1–3) or distal (L4–S1) lumbar spine increases the diameter of the spinal canal and neuroforamina and can relieve symptoms of neurogenic claudication. Distal lumbar flexion can result in pelvic retroversion; therefore, in cases of flexible sagittal imbalance, pelvic retroversion may be compensatory for lumbar stenosis and not solely compensatory for the sagittal imbalance as previously thought. The authors investigate underlying causes for pelvic retroversion in patients with flexible sagittal imbalance.

METHODS

One hundred thirty-eight patients with sagittal imbalance who underwent a total of 148 fusion procedures of the thoracolumbar spine were identified from a prospective clinical database. Radiographic parameters were obtained from images preoperatively, intraoperatively, and at 6-month and 2-year follow-up. A cohort of 24 patients with flexible sagittal imbalance was identified and individually matched with a control cohort of 23 patients with fixed deformities. Flexible deformities were defined as a 10° change in lumbar lordosis between weight-bearing and non–weight-bearing images. Pelvic retroversion was quantified as the ratio of pelvic tilt (PT) to pelvic incidence (PI).

RESULTS

The average difference between lumbar lordosis on supine MR images and standing radiographs was 15° in the flexible cohort. Sixty-eight percent of the patients in the flexible cohort were diagnosed preoperatively with lumbar stenosis compared with only 22% in the fixed sagittal imbalance cohort (p = 0.0032). There was no difference between the flexible and fixed cohorts with regard to C-2 sagittal vertical axis (SVA) (p = 0.95) or C-7 SVA (p = 0.43). When assessing for postural compensation by pelvic retroversion in the stenotic patients and nonstenotic patients, the PT/PI ratio was found to be significantly greater in the patients with stenosis (p = 0.019).

CONCLUSIONS

For flexible sagittal imbalance, preoperative attention should be given to the root cause of the sagittal misalignment, which could be compensation for lumbar stenosis. Pelvic retroversion can be compensatory for both the lumbar stenosis as well as for sagittal imbalance.

Radiologic Factors Associated With the Dynamic Change of Dural Sac Diameter in Lumbar Spine: A Kinematic MRI Study

STUDY DESIGN

This is a cross-sectional radiologic study.

OBJECTIVE

The purpose of this study was to assess radiologic features related to dynamic changes of dural sac diameter using kinematic magnetic resonance imaging.

SUMMARY OF BACKGROUND DATA

It is well known that the cross-sectional area of the lumbar spinal canal decreases during movement from flexion to extension. However, the radiologic characteristics related to dynamic changes of the lumbar spinal canal have not been elucidated.

METHODS

A total of 453 consecutive patients with clinically symptomatic low back pain or radiculopathy were recruited to undergo lumbar kinematic magnetic resonance imaging. The study participants consisted of 271 males (60%) and 182 females (40%). The average age was 44.5±12.2 years old. We investigated the following measurements at each level from L3-L4 to L5-S1: dural sac diameter, ligamentum flavum thickness, disk bulge, disk degeneration, angular motion, translational motion, and posterior disk height. The odds ratios (ORs) for ≥2 mm change of dural sac diameter between flexion and extension were calculated.

RESULTS

The average dural sac diameter was 12.2 mm in neutral, 12.5 mm in flexion, and 11.7 mm in extension, with an average difference between flexion and extension of 0.83 mm. The OR of a ≥2 mm change in L5-S1 was 0.55 as compared with L3-L4. Significantly increased ORs were observed with ≥3 mm of ligamentum flavum in neutral (OR: 4.05), 3-3.9 and ≥4 mm of disk bulge in neutral (ORs: 1.62 and 1.81, respectively), grade IV and V disk degeneration (OR: 2.59 and 2.86, respectively), ≥8 degrees of angular motion (OR: 1.81), and ≥2 mm of posterior disk height change (OR: 1.84).

CONCLUSIONS

Several radiologic characteristics related to the dynamic change of dural sac diameter have been demonstrated.