Freedman, Brett A.

OBJECTIVE The aim of this study was to determine independent risk factors for vertebral compression fracture (VCF) following stereotactic body radiation therapy (SBRT) in metastatic spine disease. METHODS Patients treated with SBRT for spinal metastasis at a single tertiary care center between 2008 and 2019 were retrospectively identified. Patients with CT scans obtained within 1 year of SBRT completion were included. Variables collected included demographics, Spine Instability Neoplastic Score (SINS), primary tumor pathology, Weinstein-Boriani-Biagini (WBB) classification, chemoradiation treatment details, and bone quality as assessed by Hounsfield units (HUs) on CT. HUs were measured for the medullary bone of the metastatic level, the tumor, and the vertebral bodies cephalad and caudal to the metastasis. Multivariable logistic regression was used to identify predictors of post-SBRT pathological fracture. RESULTS A total of 292 patients (mean age 66 years) with 392 unique lesions were included. The most common pathologies were prostate (n = 193), kidney/renal cell (n = 46), and lung (n = 33). The most common tumor levels were thoracic (n = 206 lesions) and lumbar (n = 128 lesions). SBRT was generally delivered in 1–3 fractions with doses ranging from 16 to 24 Gy in 1 fraction and 24–36 Gy in 3 fractions. Of the 392 lesions, 73 suffered VCF: 21 (29%) with < 25% height loss, 15 (21%) with 25%–40% height loss, and 37 (51%) with > 40% height loss. On univariate analysis, patients with VCF had lower average HUs (156 ± 52 vs 202 ± 89, p < 0.001), more WBB sectors involved (3 ± 2 vs 3 ± 1, p < 0.001), higher SINSs (8 ± 3 vs 6 ± 2, p < 0.001), were more commonly female (33% vs 22%, p = 0.05), and more commonly had nonprostate pathology (67% vs 47%, p = 0.003). VCF rates were similar between moderate (< 20 Gy in 1 fraction, < 30 Gy in 3 or 5 fractions) and high-dose (> 20 Gy in 1 fraction, > 30 Gy in 3 or 5 fractions) radiation schema (15% VCF vs 16% no VCF, respectively; p = 0.99). On multivariable logistic regression, independently significant predictors of VCF were HUs ≤ 229 (OR 6, p < 0.001), affected levels ≥ 3 WBB segments (OR 3, p < 0.001), and an SINS ≥ 8 (OR 2, p = 0.02). CONCLUSIONS Low pre-radiation HUs, involvement of more WBB sectors, and a higher SINS were independent predictors of VCF following SBRT for metastatic spine disease.

OBJECTIVE This study aimed to develop an artificial intelligence (AI) model for automatically detecting Hounsfield unit (HU) values at the L1 vertebra in preoperative thoracolumbar CT scans. This model serves as a screening tool for osteoporosis in patients undergoing spine surgery, offering an alternative to traditional bone mineral density measurement methods like dual-energy x-ray absorptiometry. METHODS The authors utilized two CT scan datasets, comprising 501 images, which were split into training, validation, and test subsets. The nnU-Net framework was used for segmentation, followed by an algorithm to calculate HU values from the L1 vertebra. The model’s performance was validated against manual HU calculations by expert raters on 56 CT scans. Statistical measures included the Dice coefficient, Pearson correlation coefficient, intraclass correlation coefficient (ICC), and Bland-Altman plots to assess the agreement between AI and human-derived HU measurements. RESULTS The AI model achieved a high Dice coefficient of 0.91 for vertebral segmentation. The Pearson correlation coefficient between AI-derived HU and human-derived HU values was 0.96, indicating strong agreement. ICC values for interrater reliability were 0.95 and 0.94 for raters 1 and 2, respectively. The mean difference between AI and human HU values was 7.0 HU, with limits of agreement ranging from −21.1 to 35.2 HU. A paired t-test showed no significant difference between AI and human measurements (p = 0.21). CONCLUSIONS The AI model demonstrated strong agreement with human experts in measuring HU values, validating its potential as a reliable tool for automated osteoporosis screening in spine surgery patients. This approach can enhance preoperative risk assessment and perioperative bone health optimization. Future research should focus on external validation and inclusion of diverse patient demographics to ensure broader applicability.

BACKGROUND Degenerative cervical myelopathy (DCM) is the most common cause of adult spinal cord dysfunction. Tourette syndrome (TS) represents a rare cause of DCM that is incompletely characterized in the literature. Patients with TS might develop repetitive involuntary cervical movements that can accelerate spondylotic changes. Therefore, patients with myelopathy secondary to TS or other tic disorders might exhibit DCM symptoms at younger ages. The present study examines the surgical management of DCM secondary to TS in the literature and describes the outcomes of 3 patients who were treated for DCM secondary to TS. OBSERVATIONS In these 3 described cases, fractures led to DCM in 2 patients, while cervical spondylosis led to DCM in 1 patient, all associated with TS. Treating motor tics with medications or deep brain stimulation (DBS) provided effective tic management. All 3 patients experienced improvements in their neurological symptoms following surgery, consistent with other reports in the literature. LESSONS When treating patients with cervical myelopathy secondary to TS, the authors recommend prioritizing motor tic management prior to considering secondary interventions such as surgery. According to the authors, treating motor tics with medications or DBS provides effective tic management. This approach allows for an uncomplicated postoperative course and satisfactory relief of cervical myelopathy. https://thejns.org/doi/10.3171/CASE24751

BACKGROUND AND OBJECTIVES: Transforaminal lumbar interbody fusion (TLIF) allows for direct and indirect decompression and segmental lordosis in sagittal plane correction. This study compares the effectiveness of “Bullet” type and “Banana” type devices for sagittal plane correction. METHODS: Patients who underwent 1-level or 2-level TLIF for degenerative pathology at a single tertiary care center were identified. Details were extracted on demographics, interbody dimensions, and preoperative and postoperative lumbopelvic parameters from upright radiographs. Cages were categorized as “Bullet” or “Banana” type based on morphology and manufacturer description of optimal position. Univariable comparisons between levels treated with “Bullet” and “Banana” type interbodies were performed. Multivariable linear regression was performed to identify independent predictors of postoperative segmental lordosis and change in segmental lordosis. RESULTS: One hundred and ninety eight unique patients (median 66.6 years; [IQR 59.5, 73.7]; 56.6% female) were included with 241 levels treated, of which 114 (52.7%) were treated with “Banana” type interbodies and 127 (47.3%) with “Bullet” type. “Banana” type interbodies afforded both greater postoperative segmental lordosis (8.1 [6.2, 10.7] vs 7.5 [5.2, 9.6]; P = .048) and greater increase in segmental lordosis (3.3 [0.7, 7.0] vs 2.3 [0.1, 4.2]; P = .015). On multivariable linear regression, only preoperative segmental lordosis (β = 0.322 per degree; [0.244, 0.399]; P < .001), implant listed lordosis (β = 0.146 per degree; 95% CI [0.048, 0.244]; P = .004), preoperative pelvic incidence (0.072 per degree; [0.034, 0.111]; P < .001), and use of bilateral TLIF windows (β = 3.133; [1.213, 5.053]; P = .001) were predictive of postoperative segmental lordosis. CONCLUSION: The present analysis suggests that baseline lumbopelvic anatomy, interbody lordosis, and the use of bilateral TLIF windows are the most important predictors of postoperative segmental lordosis. Use of “Banana” vs “Bullet” type interbodies was not predictive of segmental lordosis achieved on immediate postoperative upright radiographs. Further work is merited to determine whether the 2 interbody types demonstrate differences regarding subsidence risk or maintenance of correction.

Background/Objectives: Both poor bone quality and paraspinal sarcopenia have been suggested as risk factors for proximal junctional kyphosis (PJK) at the upper instrumented vertebra (UIV) following long-segment thoracolumbar fusion. Methods: Adults ≥50 with a T1-6 UIV were identified, and data were gathered on pre- and postoperative spinopelvic parameters, bone quality (using Hounsfield units and vertebral bone quality score), and paraspinal cross-sectional area at L3 and the UIV. PJK was defined by a ≥10° increase in the proximal junctional angle. Cox regressions were performed to identify PJK risk factors; PJK was subdivided into types 1–3 based on the Yagi–Boachie classification. Results: In total, 15/76 patients (median age 66; 72.4% female) experienced PJK; 10 experienced type 1, 4 experienced type 2, and one experienced type 3. Univariable Cox regression showed that PJK was negatively correlated with total paraspinal muscle CSA at the UIV (HR 0.74/100 mm2; 95% CI [0.57, 0.6]; p = 0.02). Lower total paraspinal CSA at L3 (HR 0.94/100 mm2; p = 0.07) and higher postoperative global tilt (HR 1.03; p = 0.09) also trended toward significance. Similarly, type 1 PJK was predicted by smaller total paraspinal CSA at the UIV (HR 0.64/100 mm2; [0.45, 0.92]; p = 0.02). Paraspinal CSA was not predictive of type 2 PJK, but lower HU at the UIV and UIV + 1 trended toward significance (HR 0.98/unit; p = 0.16). A comparison of type 1 and 2 PJK showed a higher average of paraspinal CSA and a lower average of HU at the UIV. Conclusions: Global alignment and paraspinal sarcopenia were most predictive of PJK, though paraspinal sarcopenia was only predictive of type 1. Type 2 may be better predicted by bone quality.

OBJECTIVE Hounsfield units (HUs) may better predict biomechanical complications of instrumented fusion than conventional bone quality measures. Typically, noncontrast axial slices are used. This study aims to address the influence of reconstruction plane and contrast administration on measured HUs in patients undergoing lumbar spine imaging. METHODS Patients without prior spine surgery, infection, or tumor were identified for 3 groups: 1) 150 patients with high-resolution noncontrast lumbar CT, 2) 109 patients with noncontrast and contrast-enhanced lumbar CT, and 3) 100 patients with noncontrast lumbar CT and lumbar CT myelograms. Noncontrast HU measures in group 1 were compared between axial, sagittal, and coronal reconstructions. HU measures for groups 2 and 3 were compared on axial slice averages. HU measures between groups were compared using the Wilcoxon signed-rank test to investigate the presence of a statistically significant difference between groups (α = 0.05). Linear regression was also used to determine the degree of correlation between HU measures on noncontrast axial CT slices and HU measures on other sequences. RESULTS The mean patient age was 58.8 ± 15.9 years for group 1 (54.0% male), 65.5 ± 15.9 years for group 2 (61.5% male), and 65.2 ± 14.2 years (53.5% male) for group 3. Comparison of HU measures in group 1 showed significant differences across measurement modalities with the exception of axial average versus coronal average measures (p = 0.257) and sagittal average versus midsagittal measures (p = 0.726). There were significant differences in average axial HUs for each vertebral body between contrast and noncontrast lumbar CT and between CT myelography and noncontrast CT. Linear regression analysis demonstrated an extremely high correlation between measures for all methodologies (r2 = 0.950–0.986, all p < 0.001), and between contrast-enhanced and noncontrast studies (r2 = 0.870, p < 0.001). Measurements on CT myelography were significantly correlated with those in noncontrast studies, although to a lesser degree (r2 = 0.745, p < 0.001). CONCLUSIONS HU measures on noncontrast CT appear similar across multiple different planes, suggesting that a simpler methodology such as single-slice measurement on midsagittal reconstruction may allow for more rapid assessment of underlying bone quality. Consistent with prior work, contrast-enhanced CT sequences appear to reliably mirror underlying bone quality, although CT myelogram measures may vary in a more unpredictable way that precludes their use to interpret underlying bone quality. HU measures on contrast-enhanced studies are on average greater, suggesting the need for higher cutoff values.

Study Design. Literature review. Objective. The goal of this study was to provide a comprehensive outline of spinal injuries that may transpire over the course of military service from traumatic to repetitive stress injuries and chronic sequelae. We considered studies that assessed spinal injuries in combat and non-combat settings as reported in the literature over the last 15 to 20 years. Background. Military service places servicemembers under substantial physical demands, while also exposing them to dangerous, unpredictable environments. As a result, servicemembers are at an increased risk of spinal injuries from combat-related trauma and other causes. They may have different care needs and recovery profiles when compared with civilians with spinal disorders. Materials and Methods. We performed a review of the available literature on spinal injuries and spinal care in the Military Health System from 2001 to the present. Results. The studies discussed in this review were primarily focused on the conflicts in both Iraq and Afghanistan from over 10 years ago and do not fully capture the present-day advancements in military technology that may have an impact on the potential for spinal injuries. The long-term effects of sustained military service and the relative influence of high demand versus sedentary military occupations on the development of spinal disorders remain poorly understood. Given the changing nature of military service, both with respect to the demographic in uniform and the ever-evolving nature of modern combat, we believe that only a long-term prospective observational study dedicated to the surveillance of spinal problems could effectively answer these questions. Conclusion. Further research into the present-day characterization of spinal injuries is warranted given the advancements in both military technology and spine care that have occurred over the last 10 years.

Study Design: Cross-sectional study. Objective: To evaluate for areas of consensus and divergence of opinion within the spine community regarding the management of cervical spondylotic conditions and acute traumatic central cord syndrome (ATCCS) and the influence of the patient's age, disease severity, and myelomalacia. Summary of Background Data: There is ongoing disagreement regarding the indications for, and urgency of, operative intervention in patients with mild degenerative myelopathy, moderate to severe radiculopathy, isolated axial symptomatology with evidence of spinal cord compression, and ATCCS without myelomalacia. Methods: A survey request was sent to 330 attendees of the Cervical Spine Research Society (CSRS) 2021 Annual Meeting to assess practice patterns regarding the treatment of cervical stenosis, myelopathy, radiculopathy, and ATCCS in 16 unique clinical vignettes with associated MRIs. Operative versus nonoperative treatment consensus was defined by a management option selected by >80% of survey participants. Results: Overall, 116 meeting attendees completed the survey. Consensus supported nonoperative management for elderly patients with axial neck pain and adults with axial neck pain without myelomalacia. Operative management was indicated for adult patients with mild myelopathy and myelomalacia, adult patients with severe radiculopathy, elderly patients with severe radiculopathy and myelomalacia, and elderly ATCCS patients with pre-existing myelopathic symptoms. Treatment discrepancy in favor of nonoperative management was found for adult patients with isolated axial symptomatology and myelomalacia. Treatment discrepancy favored operative management for elderly patients with mild myelopathy, adult patients with mild myelopathy without myelomalacia, elderly patients with severe radiculopathy without myelomalacia, and elderly ATCCS patients without preceding symptoms. Conclusions: Although there is uncertainty regarding the treatment of mild myelopathy, operative intervention was favored for nonelderly patients with evidence of myelomalacia or radiculopathy and for elderly patients with ATCCS, especially if pre-injury myelopathic symptoms were present. Level of Evidence: Level V.

Study Design Retrospective cohort study. Objective The impact of paraspinal sarcopenia following fusions that extend to the upper thoracic spine remain unknown. The purpose of the present study was to assess the impact of sarcopenia on the development of PJK and PJF following spine fusion surgery from the upper thoracic spine to the pelvis. Methods We performed a retrospective review of patients who underwent spine fusion surgery that extended caudally to the pelvis and terminated cranially between T1-6. The cohort was divided into 2 groups: (1) patients without PJK or PJF and (2) patients with PJK and/or PJF. Univariate and multivariate analyses were performed to determine risk factors for the development of proximal junctional complications. Results We identified 81 patients for inclusion in this study. Mean HU at the UIV was 186.1 ± 47.5 in the cohort of patients without PJK or PJF, which was substantially higher than values recorded in the PJK/PJF subgroup (142.4 ± 40.2) ( P < 0.001). Severe multifidus sarcopenia was identified at a higher rate in the subgroup of patients who developed proximal junction pathology (66.7%) than in the subgroup of patients who developed neither PJK nor PJF (7.4%; P < 0.001). Multivariate analysis demonstrated both low HU at the UIV and moderate-severe multifidus sarcopenia to be risk factors for the development of PJK and PJF. Conclusions Severe paraspinal sarcopenia and diminished bone density at the UIV impart an increased risk of developing PJK and PJF in following thoracolumbar fusions from the upper thoracic spine to the pelvis.

OBJECTIVE The purpose of this study was to determine the effect of osteoporosis medications on opportunistic CT-based Hounsfield units (HU). METHODS Spine and nonspine surgery patients were retrospectively identified who had been treated with romosozumab for 3 to 12 months, teriparatide for 3 to 12 months, teriparatide for > 12 months, denosumab for > 12 months, or alendronate for > 12 months. HU were measured in the L1–4 vertebral bodies. One-way ANOVA was used to compare the mean change in HU among the five treatment regimens. RESULTS In total, 318 patients (70% women) were included, with a mean age of 69 years and mean BMI of 27 kg/m 2 . There was a significant difference in mean HU improvement (p < 0.001) following treatment with romosozumab for 3 to 12 months (n = 32), teriparatide for 3 to 12 months (n = 30), teriparatide for > 12 months (n = 44), denosumab for > 12 months (n = 123), and alendronate for > 12 months (n = 100). Treatment with romosozumab for a mean of 10.5 months significantly increased the mean HU by 26%, from a baseline of 85 to 107 (p = 0.012). Patients treated with teriparatide for > 12 months (mean 23 months) experienced a mean HU improvement of 25%, from 106 to 132 (p = 0.039). Compared with the mean baseline HU, there was no significant difference after treatment with teriparatide for 3 to 12 months (110 to 119, p = 0.48), denosumab for > 12 months (105 to 107, p = 0.68), or alendronate for > 12 months (111 to 113, p = 0.80). CONCLUSIONS Patients treated with romosozumab for a mean of 10.5 months and teriparatide for a mean of 23 months experienced improved spinal bone mineral density as estimated by CT-based opportunistic HU. Given the shorter duration of effective treatment, romosozumab may be the preferred medication for optimization of osteoporotic patients in preparation for elective spine fusion surgery.