Anatomic radiological variations in developmental lumbar spinal stenosis: a prospective, control-matched comparative analysis

Congenital Stenosis of the Spine-A Cross-Sectional Study of 1019 Whole-Spine Computed Tomography Scans to Determine Prevalence and Association Among Multilevel, Tandem, and Triple Region Stenosis

BACKGOUND

Patients with congenital stenosis of the spine (CSS) present with clinical symptoms at an early age and fewer degenerative hypertrophic changes than the more common degenerative cohort. Literature is lacking in the true prevalence of CSS affecting the 3 segments of the spine in isolation, as well as in tandem in the Indian subcontinent.

METHODS

Anteroposterior spinal canal diameter in axial plane computed tomography at the midvertebral level was measured in asymptomatic patients with whole-spine computed tomography. Spinal canal stenosis was defined as a diameter of <12 mm for the cervical region, <12 mm for the thoracic region, and <13 mm for the lumbar region. Single-level and multilevel stenosis, as well as tandem and triple-region stenosis, were evaluated.

RESULTS

The results show the prevalence of CSS as 16.6%, 11.5%, and 20.1% involving the cervical, thoracic, and lumbar spine, respectively. Single-level stenosis affected 90.6%, 94%, and 79.8% of the patients with cervical, thoracic, and lumbar CSS, respectively. Tandem stenosis affected 10.4% of the population (n = 104), with cervicolumbar stenosis being the most prevalent (n = 51, 5%). The presence of CSS in any one segment of the spine was significantly associated with the presence of stenosis at one of the other segments (P < 0.05). Triple-region stenosis was seen in 0.3% (n = 3) patients.

CONCLUSIONS

The prevalence of cervical, thoracic, lumbar and tandem stenosis from our study is established at 16.6%, 11.5%, 20.1%, and 10.4%. Additionally, our study demonstrates the association between stenosis of the different regions of the spine.

Prevalence and Definition of Multilevel Lumbar Developmental Spinal Stenosis

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To define multilevel lumbar developmental spinal stenosis (DSS) using a composite score model and to determine its prevalence.

METHODS

This was a cohort study of 2385 openly recruited subjects with lumbosacral (L1-S1) MRIs. All subjects with previous spinal surgery or spinal deformities were excluded. The anteroposterior (AP) vertebral canal diameter was measured by two independent observers. Any associations between level-specific vertebral canal diameter and subject body habitus were analysed with non-parametric tests. Three or more stenotic levels, equivalent to a composite score of 3 or more, were considered as multilevel DSS. The median values of these subjects' AP canal diameters were used to construct the multilevel DSS values. Receiver operating characteristic analysis was utilized to determine the ability of these cut-off values to screen for DSS by presenting their area under curve, sensitivity and specificity.

RESULTS

Subject body habitus was poorly correlated with AP vertebral canal diameter. Multilevel DSS was identified as L1<19 mm, L2<19 mm, L3<18 mm, L4<18 mm, L5<18 mm, S1<16 mm with 81%-96% sensitivity and 72%-91% specificity. The prevalence of multilevel DSS in this cohort was 7.3%.

CONCLUSIONS

Utilizing a large homogeneous cohort, the prevalence of multilevel DSS is determined. Our cut-offs provide high diagnostic accuracy. Patients with multiple levels that fulfil these criteria may be at-risk of spinal canal compressions at multiple sites.

LEVEL OF EVIDENCE

III.

Postlaminectomy lumbopelvic sagittal changes in patients with developmental lumbar spinal stenosis grouped into Roussouly lumbopelvic sagittal profiles: 2- to 10-year prospective follow-up

OBJECTIVE

Roussouly lumbopelvic sagittal profiles are associated with distinct pathologies or distinct natural histories and prognoses. The associations between developmental lumbar spinal stenosis (DLSS) and native lumbopelvic sagittal profiles are unknown. Moreover, the relative effects of multilevel decompression on lumbar sagittal alignment, geometrical parameters of the pelvis, and compensatory mechanisms for each of the Roussouly subtypes are unknown. This study aimed to explore the association between DLSS and native lumbar lordosis (LL) subtypes. It also attempts to understand the natural history of postlaminectomy lumbopelvic sagittal changes and compensatory mechanisms for each of the Roussouly subtypes and to define the critical lumbar segment or specific lordosis arc that is recruited after relief of the stenosis effect.

METHODS

A total of 418 patients with multilevel DLSS were grouped into various Roussouly subtypes, and lumbopelvic sagittal parameters were prospectively compared at follow-up intervals of preoperative to < 2 years, 2 to < 5 years, and 5 to ≥ 10 years after laminectomy. The variables analyzed included LL, upper lordosis arc from L1 to L4, lower lordosis arc from L4 to S1, and segmental lordosis from L1 to S1. Pelvic parameters included pelvic incidence, sacral slope, pelvic tilt, and pelvic incidence minus LL values.

RESULTS

Of the 329 patients who were followed up throughout this study, 33.7% had Roussouly type 1 native lordosis, whereas the incidence rates of types 2, 3, and 4 were 33.4%, 21.9%, and 10.9%, respectively. LL was not reduced in any of the Roussouly subtypes after multilevel decompressions. Instead, LL increased by 4.5° (SD 11.9°-from 27.3° [SD 11.5°] to 31.8° [SD 9.8°]) in Roussouly type 1 and by 3.1° (SD 11.6°-from 41.3° [SD 9.5°] to 44.4° [SD = 9.7°]) in Roussouly type 2. The other Roussouly types showed no significant changes. Pelvic tilt decreased significantly-by 2.8°, whereas sacral slope increased significantly-by 2.9° in Roussouly type 1 and by 1.7° in Roussouly type 2. The critical lumbar segment that recruits LL differs between Roussouly subtypes. Increments and changes were sustained until the final follow-up.

CONCLUSIONS

The study findings are important in predicting patient prognosis, LL evolution, and the need for prophylactic or corrective deformity surgery. Multilevel involvement in DLSS and the high prevalence of Roussouly types 1 and 2 suggest that spinal canal dimensions are closely linked to the developmental evolution of LL.

Pedigree analysis of lumbar developmental spinal stenosis: Determination of potential inheritance patterns

Lumbar developmental spinal stenosis (DSS) refers to multilevel pre-existing narrowed spinal canals, which predispose to neural compromise. The objective of this study is to identify any inheritance pattern of DSS by utilizing pedigree charts. This was a case series of 13 families with a total of 80 subjects having magnetic resonance imaging (MRI) from L1 to S1. Cases (subjects with DSS) or controls (subjects without DSS) were identified by measuring their anteroposterior (AP) vertebral canal diameters. Multilevel model analyses were also performed to evaluate whether there is substantial clustering of observations within the families, and the effect of multilevel DSS. The intraclass correlation coefficient (ICC) and Akaike information criteria (AIC) were compared between models. Correlations between subject demographics and AP vertebral canal diameter were statistically insignificant at all levels. Only vertebral canal cross-sectional area, and axial and sagittal vertebral canal diameter were found to be statistically different between cases and controls at all levels (all p < .05). Both males and females were affected by DSS and there was no skipping of generation, which highly suggested DSS followed an autosomal dominant inheritance pattern. After accounting for multilevel DSS, there was a drop of more than 10 in AIC and some variances were also explained within families. This is the first study that suggests multilevel lumbar DSS to have an autosomal dominant inheritance pattern. Within families with a background of DSS, subjects had a smaller canal size, contributed by shortened axial and sagittal AP vertebral canal diameter, and smaller canal cross-sectional area.

The profile of the spinal column in subjects with lumbar developmental spinal stenosis

AIMS

The aim of this study was to determine the differences in spinal imaging characteristics between subjects with or without lumbar developmental spinal stenosis (DSS) in a population-based cohort.

METHODS

This was a radiological analysis of 2,387 participants who underwent L1-S1 MRI. Means and ranges were calculated for age, sex, BMI, and MRI measurements. Anteroposterior (AP) vertebral canal diameters were used to differentiate those with DSS from controls. Other imaging parameters included vertebral body dimensions, spinal canal dimensions, disc degeneration scores, and facet joint orientation. Mann-Whitney U and chi-squared tests were conducted to search for measurement differences between those with DSS and controls. In order to identify possible associations between DSS and MRI parameters, those who were statistically significant in the univariate binary logistic regression were included in a multivariate stepwise logistic regression after adjusting for demographics. Odds ratios (ORs) and 95% confidence intervals (CIs) were reported where appropriate.

RESULTS

Axial AP vertebral canal diameter (p < 0.001), interpedicular distance (p < 0.001), AP dural sac diameter (p < 0.001), lamina angle (p < 0.001), and sagittal mid-vertebral body height (p < 0.001) were significantly different between those identified as having DSS and controls. Narrower interpedicular distance (OR 0.745 (95% CI 0.618 to 0.900); p = 0.002) and AP dural sac diameter (OR 0.506 (95% CI 0.400 to 0.641); p < 0.001) were associated with DSS. Lamina angle (OR 1.127 (95% CI 1.045 to 1.214); p = 0.002) and right facet joint angulation (OR 0.022 (95% CI 0.002 to 0.247); p = 0.002) were also associated with DSS. No association was observed between disc parameters and DSS.

CONCLUSION

From this large-scale cohort, the canal size is found to be independent of body stature. Other than spinal canal dimensions, abnormal orientations of lamina angle and facet joint angulation may also be a result of developmental variations, leading to increased likelihood of DSS. Other skeletal parameters are spared. There was no relationship between DSS and soft tissue changes of the spinal column, which suggests that DSS is a unique result of bony maldevelopment. These findings require validation in other ethnicities and populations. Level of Evidence: I (diagnostic study) Cite this article: Bone Joint J 2021;103-B(4):725-733.

Clinical implications of lumbar developmental spinal stenosis on back pain, radicular leg pain, and disability

AIMS

To study the associations of lumbar developmental spinal stenosis (DSS) with low back pain (LBP), radicular leg pain, and disability.

METHODS

This was a cross-sectional study of 2,206 subjects along with L1-S1 axial and sagittal MRI. Clinical and radiological information regarding their demographics, workload, smoking habits, anteroposterior (AP) vertebral canal diameter, spondylolisthesis, and MRI changes were evaluated. Mann-Whitney U tests and chi-squared tests were conducted to search for differences between subjects with and without DSS. Associations of LBP and radicular pain reported within one month (30 days) and one year (365 days) of the MRI, with clinical and radiological information, were also investigated by utilizing univariate and multivariate logistic regressions.

RESULTS

Subjects with DSS had higher prevalence of radicular leg pain, more pain-related disability, and lower quality of life (all p < 0.05). Subjects with DSS had 1.5 (95% confidence interval (CI) 1.0 to 2.1; p = 0.027) and 1.8 (95% CI 1.3 to 2.6; p = 0.001) times higher odds of having radicular leg pain in the past month and the past year, respectively. However, DSS was not associated with LBP. Although, subjects with a spondylolisthesis had 1.7 (95% CI 1.1 to 2.5; p = 0.011) and 2.0 (95% CI 1.2 to 3.2; p = 0.008) times greater odds to experience LBP in the past month and the past year, respectively.

CONCLUSION

This large-scale study identified DSS as a risk factor of acute and chronic radicular leg pain. DSS was seen in 6.9% of the study cohort and these patients had narrower spinal canals. Subjects with DSS had earlier onset of symptoms, more severe radicular leg pain, which lasted for longer and were more likely to have worse disability and poorer quality of life. In these patients there is an increased likelihood of nerve root compression due to a pre-existing narrowed canal, which is important when planning surgery as patients are likely to require multi-level decompression surgery. Cite this article: Bone Joint J 2021;103-B(1):131-140.

Modified minimally invasive-transforaminal lumbar interbody fusion under microscopic view to achieve bilateral decompression and fusion through a single approach to treat developmental lumbar spinal stenosis

PURPOSE

To describe a modified minimally invasive spine (MIS) procedure to treat lumbar developmental spinal stenosis (DSS) to achieve complete decompression and fusion. The method preserves the muscles, ligaments, and most of the bony structures. DSS is not considered a good indication for MIS procedures and few reports discuss alternative treatments. Because MIS has the advantages of low blood loss, rapid recovery, and short hospital stay, it would be ideal for DSS.

METHODS

After confirming the screw positions, we placed a tube retractor in the facet joint on the decompressed side. The inferior facet joint and part of the superior joint of the lower segment were removed, the spinal canal was carefully exposed under a microscopic view, and fusion was performed through Kambin's triangle. Next, the operation table was rotated to the contralateral side and angled to approximately 15-20 degrees. We then tilted the tube retractor in the facet joint toward the operation side by 15-20 degrees, which provided access to the contralateral canal for decompression. The ligament flavum was carefully removed and the dural sac was gently retracted to expose the lateral recess on the other side. We then examined the nerve root on the contralateral side to ensure there was no compression.

RESULTS

Eight patients with lumbar DSS were treated using this method. Patients' neurological symptoms improved greatly without complications and patients were able to walk the day after surgery. The inner plate of the contralateral lamina and muscle as well as most of the ligaments that contribute to stability were preserved.

CONCLUSION

This modified MIS decompression procedure successfully treated DSS by providing spinal canal decompression and preserving most of the stabilizing structures.

Redefining lumbar spinal stenosis as a developmental syndrome: does age matter?

OBJECTIVE

Age is commonly thought to be a risk factor in defining lumbar spinal stenosis (LSS) degenerative or developmental subtypes. This article is a follow-up to a previous article ("Redefining Lumbar Spinal Stenosis as a Developmental Syndrome: An MRI-Based Multivariate Analysis of Findings in 709 Patients Throughout the 16- to 82-Year Age Spectrum") that describes the radiological differences between developmental and degenerative types of LSS. MRI-based analysis of "degeneration" variables and spinal canal morphometric characteristics of LSS segments have been thought to correlate with age at presentation.

METHODS

The authors performed a re-analysis of data from their previously reported prospective MRI-based study, stratifying data from the 709 cases into 3 age categories of equal size (instead of the original < 60 vs ≥ 60 years). Relative spinal canal dimensions, as well as radiological degenerative variables from L1 to S1, were analyzed across age groups in a multivariate mode. The total degenerative scale score (TDSS) for each lumbar segment from L1 to S1 was calculated for each patient. The relationships between age and qualitative stenosis grades, TDSS, disc degeneration, and facet degeneration were analyzed using Pearson's product-moment correlation and multiple regression.

RESULTS

Multivariate analysis of TDSS and spinal canal dimensions revealed highly significant differences across the 3 age groups at L2-3 and L3-4 and a weaker, but still significant, association with changes at L5-S1. Age helped to explain only 9.6% and 12.2% of the variance in TDSS at L1-2 and L2-3, respectively, with a moderate positive correlation, and 7.8%, 1.2%, and 1.9% of the variance in TDSS at L3-4, L4-5, and L5-S1, respectively, with weak positive correlation. Age explained 24%, 26%, and 18.4% of the variance in lumbar intervertebral disc (LID) degeneration at L1-2, L2-3, and L3-4, respectively, while it explained only 6.2% and 7.2% of the variance of LID degeneration at L4-5 and L5-S1, respectively. Age explained only 2.5%, 4.0%, 1.2%, 0.8%, and 0.8% of the variance in facet degeneration at L1-2, L2-3, L3-4, L4-5, and L5-S1, respectively.

CONCLUSIONS

Age at presentation correlated weakly with degeneration variables and spinal canal morphometries in LSS segments. Age correlated with upper lumbar segment (L1-4) degeneration more than with lower segment (L4-S1) degeneration. The actual chronological age of the patients did not significantly correlate with the extent of degenerative pathology of the lumbar stenosis segments. These study results lend support for a developmental contribution to LSS.

The influence of developmental spinal stenosis on the risk of re-operation on an adjacent segment after decompression-only surgery for lumbar spinal stenosis

Aims

The aim of this study was to determine the influence of developmental spinal stenosis (DSS) on the risk of re-operation at an adjacent level.

Patients and Methods

This was a retrospective study of 235 consecutive patients who had undergone decompression-only surgery for lumbar spinal stenosis and had a minimum five-year follow-up. There were 106 female patients (45.1%) and 129 male patients (54.9%), with a mean age at surgery of 66.8 years (sd 11.3). We excluded those with adult deformity and spondylolisthesis. Presenting symptoms, levels operated on initially and at re-operation were studied. MRI measurements included the anteroposterior diameter of the bony spinal canal, the degree of disc degeneration, and the thickness of the ligamentum flavum. DSS was defined by comparative measurements of the bony spinal canal. Risk factors for re-operation at the adjacent level were determined and included in a multivariate stepwise logistic regression for prediction modelling. Odds ratios (ORs) with 95% confidence intervals were calculated.

Results

Of the 235 patients, 21.7% required re-operation at an adjacent segment. Re-operation at an adjacent segment was associated with DSS (p = 0.026), the number of levels decompressed (p = 0.008), and age at surgery (p = 0.013). Multivariate regression model (p < 0.001) controlled for other confounders showed that DSS was a significant predictor of re-operation at an adjacent segment, with an adjusted OR of 3.93.

Conclusion

Patients with DSS who have undergone lumbar spinal decompression are 3.9 times more likely to undergo future surgery at an adjacent level. This is a poor prognostic indicator that can be identified prior to index decompression surgery.

Radiographic Cobb Angle: A Feature of Congenital Lumbar Spine Stenosis

PURPOSE

A low cost, reproducible radiographic method of diagnosing congenital lumbar spinal stenosis (CLSS) is lacking. We hypothesized that the Cobb angle for lumbar lordosis would be smaller in patients with CLSS, based on observations in our spine clinic patient population. Here, we compared lumbar lordosis Cobb angles with the radiographic ratio method in patients with normal spine imaging, degenerative spinal stenosis, and with CLSS.

MATERIALS AND METHODS

Orthopedic surgeons categorized patients with low back pain as "Normal," "Degenerative spinal stenosis," and "CLSS" based on clinical presentation and findings on lumbar magnetic resonance imaging. We included 30 patients from each cohort who had undergone lateral lumbar spine radiographs and lumbar magnetic resonance imaging. For each lateral radiograph, 2 measurement methods were used (1) 4-line lumbosacral Cobb angle between L2-S1 and (2) the ratio of the anteroposterior vertebral body diameter and spinal canal anteroposterior diameter at the L3 level. We performed logistic regression analyses of CLSS prediction by Cobb angle vs the ratio method in all three cohorts. Covariates included age, gender, and body mass index.

RESULTS

The radiographic Cobb angles were smaller in CLSS patients when compared to the degenerative disease and normal cohorts: a smaller radiographic Cobb angle showed higher odds ratio (OR) of predicting CLSS diagnosis compared to the radiographic ratio when compared with degenerative disease (OR = 0.28; 95% CI: 0.11-0.78, P = 0.01) and when compared with the normal cohort (OR = 0.46; 95% CI: 0.24-0.92, P = 0.03). Radiographic ratio measurements showed no difference between the three cohorts (P = 0.12). CLSS was associated with male gender (P = 0.04), younger age (P = 0.01), and higher body mass index (P = 0.01).

CONCLUSION

The radiographic Cobb angle method for lumbar lordosis may be useful for raising the possibility of CLSS as the diagnosis.

Redefining lumbar spinal stenosis as a developmental syndrome: an MRI-based multivariate analysis of findings in 709 patients throughout the 16- to 82-year age spectrum

OBJECTIVEUsing an imaging-based prospective comparative study of 709 eligible patients that was designed to assess lumbar spinal stenosis (LSS) in the ages between 16 and 82 years, the authors aimed to determine whether they could formulate radiological structural differences between the developmental and degenerative types of LSS.METHODSMRI structural changes were prospectively reviewed from 2 age cohorts of patients: those who presented clinically before the age of 60 years and those who presented at 60 years or older. Categorical degeneration variables at L1-S1 segments were compared. A multivariate comparative analysis of global radiographic degenerative variables and spinal dimensions was conducted in both cohorts. The age at presentation was correlated as a covariable.RESULTSA multivariate analysis demonstrated no significant between-groups differences in spinal canal dimensions and stenosis grades in any segments after age was adjusted for. There were no significant variances between the 2 cohorts in global degenerative variables, except at the L4-5 and L5-S1 segments, but with only small effect sizes. Age-related degeneration was found in the upper lumbar segments (L1-4) more than the lower lumbar segments (L4-S1). These findings challenge the notion that stenosis at L4-5 and L5-S1 is mainly associated with degenerative LSS.CONCLUSIONSIntegration of all the morphometric and qualitative characteristics of the 2 LSS cohorts provides evidence for a developmental background for LSS. Based on these findings the authors propose the concept of LSS as a developmental syndrome with superimposed degenerative changes. Further studies can be conducted to clarify the clinical definition of LSS and appropriate management approaches.

Lumbar spinal canal MRI diameter is smaller in herniated disc cauda equina syndrome patients

Introduction

Correlation between magnetic resonance imaging (MRI) and clinical features in cauda equina syndrome (CES) is unknown; nor is known whether there are differences in MRI spinal canal size between lumbar herniated disc patients with CES versus lumbar herniated discs patients without CES, operated for sciatica. The aims of this study are 1) evaluating the association of MRI features with clinical presentation and outcome of CES and 2) comparing lumbar spinal canal diameters of lumbar herniated disc patients with CES versus lumbar herniated disc patients without CES, operated because of sciatica.

Methods

MRIs of CES patients were assessed for the following features: level of disc lesion, type (uni- or bilateral) and severity of caudal compression. Pre- and postoperative clinical features (micturition dysfunction, defecation dysfunction, altered sensation of the saddle area) were retrieved from the medical files. In addition, anteroposterior (AP) lumbar spinal canal diameters of CES patients were measured at MRI. AP diameters of lumbar herniated disc patients without CES, operated for sciatica, were measured for comparison.

Results

48 CES patients were included. At MRI, bilateral compression was seen in 82%; complete caudal compression in 29%. MRI features were not associated with clinical presentation nor outcome. AP diameter was measured for 26 CES patients and for 31 lumbar herniated disc patients without CES, operated for sciatica. Comparison displayed a significant smaller AP diameter of the lumbar spinal canal in CES patients (largest p = 0.002). Compared to average diameters in literature, diameters of CES patients were significantly more often below average than that of the sciatica patients (largest p = 0.021).

Conclusion

This is the first study demonstrating differences in lumbar spinal canal size between lumbar herniated disc patients with CES and lumbar herniated disc patients without CES, operated for sciatica. This finding might imply that lumbar herniated disc patients with a relative small lumbar spinal canal might need to be approached differently in managing complaints of herniated disc. Since the number of studied patients is relatively small, further research should be conducted before clinical consequences are considered.

Stability-preserving decompression in degenerative versus congenital spinal stenosis: demographic patterns and patient outcomes

BACKGROUND CONTEXT

Although lumbar spinal stenosis often presents as a degenerative condition (degenerative stenosis [DS]), some patients present with symptoms from lifelong narrowing of the spinal canal. These patients have congenital stenosis (CS) and present with symptoms of stenosis at a younger age. Patients with CS often have a distinct pathophysiology with fewer degenerative changes but present with multilevel involvement. In the setting of neurologic symptoms, decompression alone while preserving stability has been proposed for both patient populations.

PURPOSE

The purpose of this study is to evaluate if the different etiology for narrowing in CS and DS results in a different natural history of pain progression, different locations requiring decompression, and different outcomes following a stability-preserving decompression procedure.

STUDY DESIGN/SETTING

This study used a retrospective cohort study patient sample: We retrospectively reviewed consecutive patients of a single surgeon with DS or CS who underwent surgical decompression without fusion between 2008 and 2014. Patients were excluded if they had undergone a previous lumbar surgical procedure (decompression or fusion) or follow-up less than 12 months.

OUTCOME MEASURES

Pre- and postoperative clinical outcome scores including visual analogue scale (VAS) and Oswestry Disability Index (ODI) were recorded. Postoperatively, data were collected regarding complications, the presence of new radicular or myelopathic symptoms, and necessity of reoperation in the lumbar spine.

METHODS

Demographic information included age, sex, body mass index, smoking status, and Charleston Comorbidity Index (CCI). Preoperative clinical symptoms as well as the presence of lower extremity radiculopathy and claudication were evaluated. Patients were determined to have a diagnosis of CS by the treating surgeon if primary radiographs revealed shortened pedicles and decreased cross-sectional area of the spinal canal as detailed by previous studies. Binary outcomes were compared between congenital and degenerative cohorts using bivariate and multivariate logistic regression. Multivariate regressions controlled for baseline patient and operative characteristics.

RESULTS

The average age of the DS cohort was 66.7±10.7 years, whereas for the CS group, it was 47.1±9.2 years. Average follow-up was 27.6 months. The patients with DS had significantly more comorbidities as shown by the CCI score (2.8±1.6 vs. 0.5±0.6); p<.001) and the American Society of Anesthesiologists (ASA) score ≥3 (52.8% vs. 11.1%; p<.001). Patients with CS presented with higher VAS back (8.0 vs. 5.1; p=.008) and leg (7.9 vs. 4.5; p<.001) scores. Patients with DS presented with significantly greater duration of preoperative back pain and leg pain (42.7 vs. 30.5 months; p=.042). Postoperatively, there were no significant differences in VAS back, leg, or ODI scores. However, a trend toward a lower VAS leg score was present in the patients with CS when compared with patients with DS (2.6±3.0 vs. 4.2±3.2; p<.117). Both patient groups experienced similar levels of symptomatic relief and improvement in VAS and ODI scores. There were no significant differences in new-onset radicular symptoms requiring conservative treatment or reoperation. In both groups combined, 81.9% of patients reported resolution of lower extremity symptoms at final follow-up. Overall, 20.6% of patients experienced new lower-extremity radicular symptoms after a period of resolution of symptoms postoperatively. There were significantly more reoperations following surgical decompression in patients with DS (13.9% vs. 2.8%; p=.02).

CONCLUSIONS

Patients with CS and patients with DS respond well to decompression alone, without a supplemental fusion, despite differences in pain experience and presentation. The localization of pathology requiring decompression is similar. The patients with DS were more susceptible to require another operation resulting in a fusion, which confirms the theory that initial microinstability can progress in DS, but is likely not part of the disease process in CS. At just over 2 years after decompression, patients with CS may not need to be treated by a fusion in the setting of lower back pain; however, longer-term follow up is necessary to further assess these outcomes.

Radiographic indices for lumbar developmental spinal stenosis

Background

Patients with developmental spinal stenosis (DSS) are susceptible to developing symptomatic stenosis due to pre-existing narrowed spinal canals. DSS has been previously defined by MRI via the axial anteroposterior (AP) bony spinal canal diameter. However, MRI is hardly a cost-efficient tool for screening patients. X-rays are superior due to its availability and cost, but currently, there is no definition of DSS based on plain radiographs. Thus, the aim of this study is to develop radiographic indices for diagnosing DSS.

Methods

This was a prospective cohort of 148 subjects consisting of patients undergoing surgery for lumbar spinal stenosis (patient group) and asymptomatic subjects recruited openly from the general population (control group). Ethics approval was obtained from the local institutional review board. All subjects underwent MRI for diagnosing DSS and radiographs for measuring parameters used for creating the indices. All measurements were performed by two independent investigators, blinded to patient details. Intra- and interobserver reliability analyses were conducted, and only parameters with near perfect intraclass correlation underwent receiver operating characteristic (ROC) analysis to determine the cutoff values for diagnosing DSS using radiographs.

Results

Imaging parameters from a total of 66 subjects from the patient group and 82 asymptomatic subjects in the control group were used for analysis. ROC analysis suggested sagittal vertebral body width to pedicle width ratio (SBW:PW) as having the strongest sensitivity and specificity for diagnosing DSS. Cutoff indices for SBW:PW were level-specific: L1 (2.0), L2 (2.0), L3 (2.2), L4 (2.2), L5 (2.5), and S1 (2.8).

Conclusions

This is the first study to define DSS on plain radiographs based on comparisons between a clinically relevant patient group and a control group. Individuals with DSS can be identified by a simple radiograph using a screening tool allowing for better cost-saving means for clinical diagnosis or research purposes.

PARAMETERS OF NUCLEAR MAGNETIC RESONANCE IN PATIENTS WITH CONGENITAL NARROWING OF THE LUMBAR SPINAL CANAL

ABSTRACT Objective: To compare the morphological parameters of magnetic resonance in patients with congenital narrowing of the lumbar spinal canal with patients with low back pain. Methods: A descriptive, retrospective, observational study was conducted with measurements in the axial and sagittal magnetic resonance sections of the vertebral body and canal of the lumbar spine of 64 patients with diagnosis of low back pain, which were compared with resonance images taken from 31 Mexican patients with congenital narrowing of the lumbar spinal canal. Results: The results show that patients with congenital narrowing of the lumbar spinal canal in the axial sections have a difference in diameters, being L2<13.9 mm, L3<13.3 mm, L4<12.9 mm, L5<13.1 mm, compared with controls L2<20.5 mm, L3<20.5 mm, L4<19.3 mm, L5<18.1 mm with p = 0.000. Conclusions: We found different measurements in the Mexican population compared to those found by similar studies. With the parameters obtained, it would be possible to make the proper diagnosis, surgical planning, and treatment.

Lumbar Spinal Stenosis: How Is It Classified?

The prevalence of lumbar spinal stenosis is approximately 9.3%, with people most commonly affected in the sixth or seventh decade of life. Patients often have pain, cramping, and weakness in their legs that is worsened with standing and walking. Although the Spine Patient Outcomes Research Trial clearly demonstrated that surgery improves health-related quality of life, treatment for lumbar spinal stenosis varies widely from the type of decompression performed to the need for fusion. This variability can be attributed largely to the lack of an accepted classification system. A good classification system serves as a common language to define the severity of a condition, guide treatment, and facilitate clinical research.

The paradoxical relationship between ligamentum flavum hypertrophy and developmental lumbar spinal stenosis

Background

Ligamentum flavum (LF) hypertrophy is a common cause of lumbar spinal stenosis and is thought to be degeneration-driven. Developmental spinal stenosis (DSS) is characterized by pre-existing narrowed spinal canals and is likely a developmental problem that occurs in childhood. In these cases, the LF may demonstrate different characteristics as compared to degeneration-driven stenosis. Thus, this study aimed to investigate the relationship between histological changes of LF and canal size.

Methods

Patients who had surgical decompression for lumbar spinal stenosis were prospectively recruited and divided into three groups (critical DSS, relative DSS and non-DSS) based on previously defined anteroposterior bony spinal canal diameter measurements on MRI. The degree of disc degeneration and LF thickness were also measured from L1 to S1. Surgical LF specimens were retrieved for histological assessment of fibrotic grade and area of fibrosis.

Results

A total of 19 females and 15 males (110 LF specimens) with an overall mean age of 65.9 years (SD ± 9.8 years) were recruited. DSS was found to have a significant negative correlation (p < 0.001) with LF thickness, its fibrotic grade and area of fibrosis (%). Non-DSS exhibited a significant positive relationship with the degree of LF fibrosis. Disc degeneration and LF thickness had no correlation with LF histology.

Conclusions

Our study is the first to definitively note that degeneration is the cause of LF fibrosis in non-DSS patients; however, in contrast, an inverse relationship exists between canal size and LF fibrosis in DSS patients, suggesting a different pathomechanism. Hence, despite a similar degree of LF thickness, DSS patients have LF with less fibrosis compared with non-DSS patients. Further investigation of the cause of LF changes in DSS is necessary to understand this relationship.

Spectrum of magnetic resonance imaging findings in congenital lumbar spinal stenosis

AIM: To investigate whether congenital lumbar spinal stenosis (CLSS) is associated with a specific degenerative changes of the lumbar spine.

METHODS: The lumbar spine magnetic resonance imaging studies of 52 subjects with CLSS and 48 control subjects were retrospectively evaluated. In each examination, the five lumbar levels were assessed for the presence or absence of circumferential or shallow annular bulges, annular tears, anterior or posterior disc herniations, epidural lipomatosis, Schmorl’s nodes, spondylolisthesis, pars defects, and stress reactions of the posterior vertebral elements.

RESULTS: Compared to control individuals, subjects with CLSS exhibited increased incidence of circumferential and shallow annular bulges, annular tears, disc herniations and spondylolisthesis (P < 0.05).

CONCLUSION: CLSS is associated with increased incidence of degenerative changes in specific osseous and soft-tissue elements of the lumbar spine.