Sagittal Normal Limits of Lumbosacral Spine in a Large Adult Population: A Quantitative Magnetic Resonance Imaging Analysis

Risk Factors for Neurologic Deficits in Patients With Spinal Epidural Abscess: An Analysis of One-Hundred-Forty Cases

STUDY DESIGN

retrospective study.

OBJECTIVES

In addition to surgical treatment of spinal epidural abscesses (SEA), a conservative, medical treatment for patients without acute neurologic deficits has been proposed. However, the risk factors for neurologic deficits are unclear. This study aims to identify factors predisposing patients with SEA to neurological impairment.

METHODS

All patients treated for SEA between 2008 and 2021 were identified from a prospective vertebral-osteomyelitis registry of a tertiary referral centre. Patient demographics, comorbidities, pathogens, degree of osseous destruction, location of SEA and preoperative neurologic status were retrospectively collected. Differences between patients with (Group 1) and without (Group 2) pretreatment neurologic deficits were assessed by univariate and logistic regression analysis.

RESULTS

A total of 140 patients with SEA were included. Forty-three patients (31%) had a neurologic deficit and 97 patients (69%) had no neurologic deficit prior to therapy. The prevalence of diabetes mellitus (35% vs 19%, P = .03), median visual analogue scale leg pain (8 vs 5, P = .01), median American Society of Anesthesiologists (ASA) Score (3 vs 2.6, P = .003) and mean Body-Mass-Index (29 vs 26, P = .02) differed between Group 1 and 2 in univariate analysis. In multivariable analysis, diabetes mellitus (odds ratio = 2.7), female sex (odds ratio = 2.5) and ASA-Score (odds ratio = 2.4) were significant contributors for neurologic deficits.

CONCLUSIONS

In patients with a SEA without neurologic deficits, the ASA score and diabetes mellitus should be considered, especially in female patients. These patients may be at a higher risk for developing a neurologic deficit and may benefit from an early surgical treatment.

Evaluation of 2 Novel Ratio-Based Metrics for Lumbar Spinal Stenosis

BACKGROUND AND PURPOSE

Quantitative metrics of the dural sac such as the cross-sectional area are commonly used to evaluate central canal stenosis. The aim of this study was to analyze 2 new metrics to measure spinal stenosis on the basis of the ratio between the dural sac and disc cross-sectional areas (DDRCA) and the dural sac and disc anterior-posterior diameters (DDRDIA) and compare them with established quantitative metrics of the dural sac.

MATERIALS AND METHODS

T2-weighted axial MR images (n = 260 patients) were retrospectively evaluated, graded for central canal stenosis as normal (no stenosis), mild, moderate, or severe from L1/L2 through L5/S1 with 1 grade per spinal level and annotated to measure the DDRCA and DDRDIA. Thresholds were obtained using a decision tree classifier on a subset of patients (n = 130) and evaluated on the remaining patients (n = 130) for accuracy and consistency across demographics, anatomic variation, and clinical outcomes.

RESULTS

DDRCA and DDRDIA had areas under the receiver operating characteristic curve of 98.6 (97.4-99.3) and 98.0 (96.7-98.9) compared with dural sac cross-sectional area at 96.5 (95.0-97.7) for binary classification. DDRDIA and DDRCA had κ scores of 0.75 (0.71-0.79) and 0.80 (0.75-0.83) compared with dural sac cross-sectional area at 0.62 (0.57-0.66) for multigrade classification. No significant differences (P > .1) in the area under the receiver operating characteristic curve were observed for the DDRDIA across variations in the body mass index. The DDRDIA also had the highest area under the receiver operating characteristic curve among symptomatic patients (visual analog scale ≥ 7) or patients who underwent surgery.

CONCLUSIONS

Ratio-based metrics (DDRDIA and DDRCA) are accurate and robust to anatomic and demographic variability compared with quantitative metrics of the dural sac and better correlated with symptomatology and surgical outcomes.

Radiographic analysis of neuroforaminal and central canal decompression following lateral lumbar interbody fusion

Background

Lateral lumbar interbody fusion (LLIF) is a minimally invasive surgical option for treating symptomatic degenerative lumbar spinal stenosis (DLSS) in select patients. However, the efficacy of LLIF for indirectly decompressing the lumbar spine in DLSS, as well as the best radiographic metrics for evaluating such changes, are incompletely understood.

Methods

A single-institutional cohort of patients who underwent LLIF for DLSS between 5/2015 – 12/2019 was retrospectively reviewed. Diameter, area, and stenosis grades were measured for the central canal (CC) and neural foramina (NF) at each LLIF level based on preoperative and postoperative T2-weighted MRI. Baseline facet joint (FJ) space, degree of FJ osteoarthritis, presence of spondylolisthesis, interbody graft position, and posterior disc height were analyzed as potential predictors of radiographic outcomes. Changes to all metrics after LLIF were analyzed and compared across lumbar levels. Preoperative and intraoperative predictors of decompression were then assessed using multivariate linear regression.

Results

A total of 102 patients comprising 153 fused levels were analyzed. Pairwise linear regression of stenosis grade to diameter and area revealed significant correlations for both the CC and NF. All metrics except CC area were significantly improved after LLIF (p < 0.05, 2-tailed t-test). Worse FJ osteoarthritis ipsilateral to the surgical approach was predictive of greater post-operative CC and NF stenosis grade (p < 0.05, univariate and multivariate ordinary least squares linear regression). Lumbar levels L3-5 had significantly higher absolute postoperative CC stenosis grades while relative change in CC stenosis at the L2-3 was significantly greater than other lumbar levels (p < 0.05, one-way ANOVA). There were no baseline or postoperative differences in NF stenosis grade across lumbar levels.

Conclusions

Radiographically, LLIF is effective at indirect compression of the CC and NF at all lumbar levels, though worse FJ osteoarthritis predicted higher degrees of post-operative stenosis.

Severity and location of lumbar spine stenosis affects the outcome of total knee arthroplasty

Background

Recent studies have noted that patients with pre-existing lumbar spinal stenosis (LSS) have lower functional outcomes after total knee arthroplasty (TKA). Given that LSS manifests heterogeneously in location and severity, its influence on knee replacement merits a radiographically targeted analysis. We hypothesize that patients with more severe LSS will have diminished knee mobility before and after TKA.

Methods

This retrospective case series assessed all TKAs performed at our institution for primary osteoarthritis from 2017–2020. Preoperative lumbar magnetic resonance image (MRI) with no prior lumbar spine surgery was necessary for inclusion. Stenosis severity was demonstrated by (1) anterior–posterior (AP) diameter of the thecal sac and (2) morphological grade. TKA outcomes in 103 cases (94 patients) were assessed by measuring preoperative and postoperative arc of motion (AOM), postoperative flexion contracture, and need for manipulation under anesthesia.

Results

Patients with mild stenosis did significantly better in terms of postoperative knee AOM. As AP diameter decreased at levels L1–2, L2–3, L3–4, and L4–5, there was a significant reduction in preoperative-AOM (p < 0.001 for each), with a 16 degree decrease when using patients’ most stenotic level (p < 0.001). The same was noted with respect to increased morphological grade (p < 0.001), with a 5 degree decrease for patients’ most stenotic level (p < 0.001).

Conclusion

Severe LSS, which is readily demonstrated by a reduction in the AP diameter of the thecal sac or increased morphological grade on MRI, correlated with a significant reduction in preoperative AOM that was not improved after TKA. Persistent postoperative reductions in AOM may contribute to reduced patient satisfaction and recovery.

Level of evidence: Level 4

Surgical Evaluation and Management of Spinal Pathology in Patients with Connective Tissue Disorders

Connective tissue disorders represent a varied spectrum of syndromes that have important implications for the spine deformity surgeon. Spine surgeons must be aware of these diverse and global manifestations of disease because they have significant impact on perioperative and postoperative outcomes.

Dural ectasia in Marfan syndrome and other hereditary connective tissue disorders: a 10-year follow-up study

BACKGROUND CONTEXT

Dural ectasia is widening of the dural sac often seen in patients with Marfan syndrome and other hereditary connective tissue disorders. Dural ectasia can cause specific symptoms and is associated with surgical complications. The knowledge on how and at which age dural ectasia develops is incomplete. There is no established gold standard for diagnosing dural ectasia, making it difficult to compare results from different studies.

PURPOSE

Our primary aim was to explore whether the radiological findings of dural ectasia changed after 10 years in an adult cohort with suspected Marfan syndrome. Our secondary aim was to re-evaluate the radiological criteria of dural ectasia.

STUDY DESIGN

Prospective cohort study.

PATIENT SAMPLE

Sixty-two persons from a cross-sectional study of 105 persons with suspected Marfan syndrome were included in a 10-year follow-up of dural ectasia. Forty-six were diagnosed with Marfan syndrome, 7 with Loeys-Dietz syndrome, and 5 with other hereditary connective tissue disorders. For comparison 64 matched hospital controls were evaluated.

OUTCOME MEASURES

Previously used radiological criteria for dural ectasia based on quantitative measurements of the lumbosacral spine.

METHODS

MRI of the lumbosacral spine was performed if not contraindicated, and if so then CT was performed. Differences in the study group between baseline and follow-up were assessed with paired Student t test, Wilcoxon rank signed test, and McNemar test. Receiver operating characteristic curves were constructed to assess the ability of radiological measurement to differentiate between the study and control group.

RESULTS

Fifty-two of 58 patients with hereditary connective tissue disorders and 11 controls had dural ectasia at follow-up. Forty-five Marfan patients had dural ectasia at follow-up vs. 41 at baseline. Five Loeys-Dietz patients had dural ectasia at follow-up vs. four at baseline. Twenty-four Marfan and 2 Loeys-Dietz patients had anterior sacral meningocele at follow-up, compared with 21 and 1, respectively, at baseline. Three Marfan patients developed herniation of a nerve root sleeve during follow-up. This was not seen in other individuals. The dural sac ended significantly lower at follow-up, and the dural sac ratio at level L5 was significantly increased from baseline in the Marfan patients.

CONCLUSIONS

In Marfan and Loeys-Dietz syndrome, dural ectasia may present or worsen during adulthood. The cut-off value of dural sac ratio at level S1 is suggested elevated to 0.64. The results from the present study may help as guidance for appropriate follow-up of patients with dural ectasia.