Comparing the Upper Instrumented Vertebrae Tilt Angle vs Screw Angle in the Development of Proximal Junction Kyphosis After Adult Spinal Deformity Surgery: Which Matters More?

BACKGROUND: We sought to determine which aspect of the upper instrumented vertebrae (UIV)-tilt angle or screw angle-was more strongly associated with: (1) proximal junctional kyphosis/failure (PJK/F), (2) other mechanical complications and reoperations, and (3) patient-reported outcome measures (PROMs). METHODS: A single-institution, retrospective cohort study was undertaken for patients undergoing adult spinal deformity (ASD) surgery from 2011 to 2017. Only patients with UIV at T7 or below were included. The primary exposure variables were UIV tilt angle (the angle of the UIV inferior endplate and the horizontal) and UIV screw angle (the angle of the UIV screws and superior endplate). Multivariable logistic regression included age, body mass index, osteopenia/osteoporosis, postoperative sagittal vertical axis, postoperative pelvic-incidence lumbar lordosis mismatch, UIV tilt angle, and UIV screw angle. RESULTS: One hundred and seventeen patients underwent adult spinal deformity surgery with a minimum of 2-year follow-up. A total of 41 patients (35.0%) had PJK and 26 (22.2%) had PJF. (1) UIV tilt angle: 96 (82.1%) had lordotic UIV tilt angles, 6 (5.1%) were neutral, and 15 (12.8%) were kyphotic. (2) UIV screw angle: 38 (32.5%) had cranially directed screws, 4 (3.4%) were neutral, and 75 (64.1%) were caudally directed. Both lordotic-angled UIV endplate (OR = 1.06, 95% CI = 1.01-1.12, and P = 0.020) and cranially directed screws (OR = 1.19, 95% CI = 1.07-1.33, and P < 0.001) were associated with higher odds of PJK, with a more pronounced effect of UIV screw angle compared with UIV tilt angle (Wald test, 9.40 vs 4.42). Similar results were found for PJF. Neither parameter was associated with other mechanical complications, reoperations, or patient-reported outcome measures. CONCLUSIONS: UIV screw angle was more strongly associated with development of PJK/F compared with tilt angle. Overall, these modifiable parameters are directly under the surgeon's control and can mitigate the development of PJK/F. CLINICAL RELEVANCE: Surgeons may consider selecting a UIV with a neutral or kyphotically directed UIV tilt angle when performing ASD surgery with a UIV in the lower thoracic or lumbar region, as well as use UIV screw angles that are caudally directed, for the purprose of decreasing the risk of developing PJK/F.

A comprehensive review on the development of sporadic cerebral arteriovenous malformations: from Padget to next-generation sequencing.

Cerebral arteriovenous malformations (AVMs) are a leading cause of intracerebral hemorrhage in both children and young adults. With the continued advancement of science and technology, the understanding of the pathophysiology behind the development of these lesions has evolved. From early theory published by Harvey Cushing and Percival Bailey in 1928, Tumors Arising from the Blood-vessels of the Brain: Angiomatous Malformations and Hemangioblastoma, which regarded AVMs as tumors arising from blood vessels, to the meticulous artistry of Dorcas Padget's embryological cataloguing of the cerebral vasculature in 1948, to the proliferative capillaropathy theory of Yasargil in 1987, to Ramey's 2014 hierarchical model of vascular development, there have been multiple hypotheses of congenital, developmental, and genetic two-hit theories in the pathogenesis of AVMs. Most recent evidence implicates somatic KRAS mutations in the cerebral endothelium, producing an important understanding of the pathogenesis of this disease, which is critical to the development of targeted therapeutics. The authors present the historical progression of their understanding of AVM pathogenesis. They focus on the foundation laid by early pioneers, discussing embryological anatomy and vasculogenesis, the prominent theories of AVM development that have emerged over time, and culminate in an overview of the most current understanding of the pathogenesis of these complex vascular lesions and the clinical implications of our scientific progress.

Longer Screws Decrease the Risk of Radiographic Pseudarthrosis Following Elective Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: In patients undergoing elective anterior cervical discectomy and fusion (ACDF), we sought to determine the impact of screw length on: (1) radiographic pseudarthrosis, (2) pseudarthrosis requiring reoperation, and (3) patient-reported outcome measures (PROMs). METHODS: A single-institution, retrospective cohort study was undertaken from 2010-21. The primary independent variables were: screw length (mm), screw length divided by the anterior-posterior vertebral body diameter (VB%), and the presence of any screw with VB% < 75% vs all screws with VB% ≥ 75%. Multivariable logistic regression controlled for age, BMI, gender, smoking, American Society of Anesthesiology grade, number of levels fused, and whether a corpectomy was performed. RESULTS: Of 406 patients undergoing ACDF, levels fused were: 1-level (39.4%), 2-level (42.9%), 3-level (16.7%), and 4-level (1.0%). Mean screw length was 14.3 ± 2.3 mm, and mean VB% was 74.4 ± 11.2. A total of 293 (72.1%) had at least one screw with VB% < 75%, 113 (27.8%) had all screws with VB% ≥ 75%, and 141 (34.7%) patients had radiographic pseudarthrosis at 1-year. Patients who had any screw with VB% < 75% had a higher rate of radiographic pseudarthrosis compared to those had all screws with VB% ≥ 75% (39.6% vs 22.1%, P < .001). Multivariable logistic regression revealed that a higher VB% (OR = .97, 95%CI = .95-.99, P = .035) and having all screws with VB% ≥ 75% (OR = .51, 95%CI = .27-.95, P = .037) significantly decreased the odds of pseudarthrosis at 1-year, with no difference in reoperation or PROMs (all P > .05). CONCLUSION: Longer screws taking up ≥75% of the vertebral body protected against radiographic pseudarthrosis at 1-year. Maximizing screw length in ACDF is an easily modifiable factor directly under the surgeon's control that may mitigate the risk of pseudarthrosis.

Lumbopelvic postural differences in adolescent idiopathic scoliosis: A pilot study.

BACKGROUND: A primary etiology of adolescent idiopathic scoliosis (AIS) is currently unknown, but poor postural control of the spinal extensor musculature has been identified as an AIS risk factor. Identifiable postural differences would aid in advancing the precise postural behaviors that should be modified during Physiotherapy Scoliosis Specific Exercise (PSSE) to help limit the progression of AIS. RESEARCH QUESTION: Are there any determinable differences in lumbopelvic posture or range of motion between subjects with AIS and controls? METHODS: This prospective cohort pilot study consisted of 53 subjects (27 AIS and 26 control) aged 11-17 years. Subjects had their lumbopelvic posture assessed and monitored using the ViMove DorsaVi sensor package. All subjects underwent a live assessment to obtain initial lumbopelvic (LP) range of motion (ROM) measurements. Subjects were then monitored while continuing with normal activities of daily living (ADLs) for 12 h. With an alpha level of 0.05, nonparametric analyses were performed for each variable via a Mann-Whitney U-test. RESULTS: During the live assessment, controls exhibited a significantly greater anterior pelvic tilt ROM in the sitting position than the AIS group (p = 0.0433). When compared to female controls, females with AIS had a sitting pelvic tilt ROM that was significantly more retroverted (p = 0.0232) and less anteverted (p = 0.0010). During ADLs, female controls exhibited a higher total number of extension events than their female with AIS (p = 0.0263). These associations did not strengthen with greater spinal deformity. SIGNIFICANCE: This work demonstrates postural differences between patients with AIS and controls. Further study is necessary to determine why patients with AIS adopt these postures, and if PSSEs can be utilized to limit the progression of AIS.

National trends in the surgical management of metastatic lung cancer to the spine using the national inpatient sample database from 2005 to 2014.

Optimal management of metastatic lung cancer to the spine (MLCS) incorporates a multidisciplinary approach. With improvements in lung cancer screening andnonsurgical treatment, the role for surgerymay be affected. The objective of this study is to assess trends in the surgical management of MLCS using the National Inpatient Sample (NIS) database. The NIS was queried for patients with MLCS who underwent surgery from 2005 to 2014. The frequencies of spinal decompression alone, spinal stabilization with or without (+/-) decompression, and vertebral augmentation were calculated. Statistical analysis was performed to analyze the effect of patient characteristics on outcomes. The most common procedure performed was vertebral augmentation (10719, 44.3%), followed by spinal stabilization +/- decompression (8634, 35.7%) and then decompression alone (4824, 20.0%). The total number of surgeries remained stable, while the rate of spinal stabilizations increased throughout the study period (p < 0.001). Invasive procedures such as stabilization and decompression were associated with greater costs, length of stay,complications and mortality. Increasingcomorbidity was associated with increased odds of complication, especially in patients undergoing more invasive procedures. In patients with lowpre-operative comorbidity, the type of procedure did not influence the odds of complication. Graded increases in length of stay, cost and mortality were seen with increasing complication rate.The rate of spinal stabilizations increased, which may be due to either increased early detection of disease facilitating use of outpatient vertebral augmentation procedures and/or the recognition that surgical decompression and stabilization are necessary for optimal outcome in the setting of MLCS with neurological deficit.

A novel method for ex-vivo latex angiography of the mouse brain.

INTRODUCTION: Latex perfusion is an effective tool to study cerebrovascular pathology in the animal brain. It provides, low-cost, high fidelity anatomical information on ex-vivo analysis, and can be utilized to study multiple, states. However, current methods of latex casting and tissue-clearance do not allow for immunohistochemical analysis following sample processing. This results in experiments that require increased numbers of animals to attain adequate data. NEW METHOD: In this paper, we present a modified latex perfusion and tissue processing protocol for ex-vivo analysis, of the cerebral vasculature. The method consists of injection of the arterial tree with liquid latex, followed by tissue clearance with a scale solution. RESULTS: Our results demonstrate effective and reliable perfusion of the murine cerebrovascular tree, rendering the arterial morphology of the brain in high detail, while allowing for post-perfusion, immunohistochemistry of the sample. COMPARISON WITH EXISTING METHOD: Our technique bypasses the limitations of previous latex angiography protocols by allowing for postperfusion, pathologic analysis of casted cerebrovascular tissue. CONCLUSION: This protocol provides a reliable, low-cost, method of cerebrovascular perfusion that reduces the number of animals required to generate robust data from latex-casted brain tissue.

Current trends in incidence, characteristics, and surgical management of metastatic breast cancer to the spine: A National Inpatient Sample analysis from 2005 to 2014.

Management of metastatic breast cancer to the spine (MBCS) incorporates a multimodal approach. Improvement in screening and nonsurgical therapies may alter the trends in surgical management of MBCS. The objective of this study is to assess trends in surgical management of MBCS and short-term outcomes based on the National Inpatient Sample (NIS) database. The NIS database was queried for patients with MBCS who underwent surgery from 2005 to 2014. The weighted frequencies of spinal decompression alone, spinal stabilization +/- decompression, and vertebral augmentation were calculated. Multivariate analysis was performed to analyze the effect of patient characteristics on outcomes stratified by procedure. The most common procedure performed was vertebral augmentation (11,114, 53.4%), followed by stabilization +/- decompression (6,906, 33.2%) and then decompression alone (3,312, 13.4%). The total population-adjusted rate of surgical management for MBCS remained stable, while the rate of spinal stabilization increased (P < 0.001) and vertebral augmentation decreased (p < 0.003). The risk of complication increased with spinal stabilization and decompression compared to vertebral augmentation procedures in those with fewer comorbidities. This relative increase in risk abated in patients with higher numbers of pre-operative comorbidities. Any single complication was associated with increases in length of stay, cost, and mortality. The rate of in-hospital interventions remained stable over the study period. Stratified by procedure, the rate of stabilizations increased with a concomitant decrease in vertebral augmentations, which suggests that patients who require hospitalization for MBCS are becoming more likely to represent advanced cases that are not amenable to palliative vertebral augmentation procedures.

Predictors of Citations in Neurosurgical Research: A 5-Year Follow-Up.

BACKGROUND: Citation rates are an important measure for the impact of articles. This study is the most comprehensive analysis of predictors for scientific neurosurgical research articles. METHODS: Scientific articles published in 13 neurosurgical journals in 2015 were selected. Data collected included article subject, level of evidence (LOE), journal impact factor (IF), authorship, contributing centers, and study design. Citation counts were collected for each article in Web of Science (WoS) and Google Scholar (GS) 2.5 and 5 years after publication and Scopus 5 years after publication. A generalized linear mixed-effects model using the predictors of search engine, LOE, number of centers, number of authors, and IF was constructed to predict total citation count at 5 years. RESULTS: A total of 2867 articles generated 39,190 citations in WoS, 61,682 in GS, and 43,481 in Scopus. The median number of citations per article was 10 (interquartile range [IQR], 14) in WoS, 15 (IQR, 20) in GS, and 11 (IQR, 15) in Scopus. On average, for every 1 citation in WoS, Scopus and GS identified 1.11 and 1.58 citations, respectively. Significant predictors of citation count in all databases 5 years after publication included search engine, LOE, number of centers, number of authors, number of countries, journal IF, and the month of publication (P < 0.05). The article subject (e.g., tumor or spine) did not significantly predict citation counts. CONCLUSIONS: In the most thorough analysis of citation predictors in the neurosurgical literature, search engine, LOE, number of centers, number of authors, number of countries, journal impact factor, and month of publication influenced citations 5 years after publication.

Factors associated with length of stay after single-level posterior thoracolumbar instrumented fusion primarily for degenerative spondylolisthesis.

BACKGROUND: The postoperative length of stay (LOS) is an important prognostic indicator for patients undergoing instrumented spinal fusion surgery. Increased LOS can be associated with higher infection rates, higher incidence of venous thromboembolisms, and a greater frequency of hospital-acquired delirium. The day of surgery and early postoperative mobilization following single-level posterior thoracolumbar stabilizations may impact the LOS. In this study, we evaluated the effects of weekday (Monday-Thursday) versus weekend (Friday-Sunday) surgery and postoperative rehabilitation services on LOS following primarily transforaminal lumbar interbody fusion (TLIF) for degenerative spondylolisthesis (DS). METHODS: In this single-institution retrospective chart review, we identified 198 adults who received a one-level thoracolumbar instrumented fusion through a posterior only approach (2017-2019). The majority of these patients underwent TLIF for DS. A zero truncated negative binomial model was used for predictors of the primary outcome of LOS (weekday of surgery, duration of operation, first or repeat surgery, and physical therapy/ occupational therapy [PT/OT] evaluation). Covariates were sex, age, and body mass index. RESULTS: We found that operative duration, repeat surgery, and in-hospital PT/OT all significantly increased the LOS (P < 0.05). Furthermore, those undergoing weekday surgery (Monday-Thursday) had 1.29 times longer LOS than those on the weekend (Friday-Sunday), but this did not reach statistical significance (P = 0.09). CONCLUSION: In our patient sample, duration, repeat surgery, and in-hospital PT/OT increased the LOS following primarily TLIF for DS. The increased LOS in these cases is likely due to higher overall disease burden and case complexity. In addition, those patients with a greater likelihood of extended recovery and ongoing neurologic deficits are more likely to have PT/OT evaluations. Notably, LOS was not significantly impacted by the day of surgery at our institution.

Somatic Mosaicism in the Pathogenesis of de novo Cerebral Arteriovenous Malformations: A Paradigm Shift Implicating the RAS-MAPK Signaling Cascade.

Cerebral arteriovenous malformations (AVMs) are leading causes of lesional hemorrhagic stroke in both the pediatric and young adult population, with sporadic AVMs accounting for the majority of cases. Recent evidence has identified somatic mosaicism in key proximal components of the RAS-MAPK signaling cascade within endothelial cells collected from human sporadic cerebral AVMs, with early preclinical models supporting a potential causal role for these mutations in the pathogenesis of these malformations. Germline mutations that predispose to deregulation of the RAS-MAPK signaling axis have also been identified in hereditary vascular malformation syndromes, highlighting the key role of this signaling axis in global AVM development. Herein, we review the most recent genomic and preclinical evidence implicating somatic mosaicism in the RAS-MAPK signaling pathway in the pathogenesis of sporadic cerebral AVMs. Also, we review evidence for RAS-MAPK dysregulation in hereditary vascular malformation syndromes and present a hypothesis suggesting that this pathway is central for the development of both sporadic and syndrome-associated AVMs. Finally, we examine the clinical implications of these recent discoveries and highlight potential therapeutic targets within this signaling pathway.

Angiographic cerebral venous sinus calibers and drainage patterns in patients with normal intracranial pressure and idiopathic intracranial hypertension.

BACKGROUND: Normative venous sinus diameters are not well established. This study seeks to compare two-dimensional digital subtraction cerebral angiographic (DSA) venous sinus calibers for patients with normal intracranial pressure (ICP) and with idiopathic intracranial hypertension (IIH). METHODS: Patients who underwent diagnostic cerebral angiography from 2016 to 2020 were retrospectively identified. Two independent reviewers measured venous sinus calibers from anteroposterior (AP) and lateral carotid injection delayed venous phase in patients from two groups (group 1: patients with normal ICP; group 2: patients with IIH) after receiving training in a standardized measurement protocol, with measurements obtained from the superior sagittal sinus (SSS) through the sigmoid sinuses (SS). RESULTS: 97 patients from group 1 and 30 patients from group 2 were included. Interrater reliability was greater than 0.75 for all measured sites. Both groups had similar anatomical subtypes with most being right transverse sinus (TS) dominant or codominant. In group 1, men had significantly larger SSS on lateral view (p<0.001) and dominant TS calibers on AP view (p=0.02) compared with women. Both dominant TS measurements and SSS measurements (lateral plane) were significantly smaller among group 2 compared with group 1 (p<0.001 and 0.02, respectively). Patients with IIH had significantly larger dominant SS measurements (p=0.01). Bifid SSS anatomy was present in 9% of patients with mean caudal width 31 mm (range 19-49 mm). CONCLUSIONS: This study is the first to provide two-dimensional DSA dural venous sinus calibers in patients with and without IIH and to compare anatomical drainage types and calibers among groups.

Addressing the epilepsy surgery gap: Impact of community/tertiary epilepsy center collaboration.

To assess whether a formal collaboration between a non-surgical, community epilepsy center and a surgical, tertiary-care epilepsy center can improve patient progress throughout the pre-surgical referral process, and to elucidate predictors of referral completion among inter-center referrals. The inter-center referral process was tracked, and the number of patients completing surgical conference (primary outcome) and epilepsy surgery at the tertiary center were collected and compared in the 45-month immediate pre/post-collaboration periods. Demographic and clinical variables were collected on post-collaboration inter-center patient referrals to explore factors associated with completion of the referral process. Compared to the pre-collaboration period, the proportion of tertiary center epilepsy surgery conference patients referred from the community epilepsy center increased from 3/88 to 14/113 (263% increase, p = .01) during the post-collaboration period. The proportion of patients completing surgery via the community to tertiary referral process increased from 2/63 pre-collaboration to 8/71 post-collaboration (254% increase, p = .04). Referral completion was associated with higher seizure frequency, shorter travel distance, private insurance status and positive employment status (p < 0.05). Collaboration agreements between community and tertiary-care epilepsy centers may improve patient completion of the epilepsy surgery referral process. Implementation of similar programs at other centers may be beneficial in reducing the epilepsy surgery gap.

Changes in the Operative Corridor in Oblique Lumbar Interbody Fusion Between Preoperative Magnetic Resonance Imaging and Intraoperative Cone-Beam Computed Tomography Using Morphometric Analysis.

Background The oblique lumbar interbody fusion or anterior-to-psoas (OLIF/ATP) technique relies on a corridor anterior to the psoas and posterior to the vasculature for lumbar interbody fusion. This is evaluated preoperatively with CT and/or MRI. To date, there have been no studies examining how intraoperative, lateral decubitus positioning may change the dimensions of this corridor when compared to preoperative imaging. Objective Our objective was to evaluate changes in the intraoperative corridor in the supine and lateral positions utilizing preoperative and intraoperative imaging. Methods We performed a retrospective analysis among patients who have undergone an OLIF/ATP approach at two tertiary care centers from 2016 to 2018 by measuring the distance between the left lateral border of the aorta or iliac vessels and anteromedial border of the psoas muscle from L1-L2 through L4-5 disc spaces. We compared this corridor between supine, preoperative MRI axial and intraoperative CT acquired in the right lateral decubitus position. Results Thirty-three patients, 15 of whom were female, were included in our study. The average age of the patients was 65.4 years and the average BMI was 31 kg/m2. The results revealed a statistically significant increase (p<.05) in the intraoperative corridor from supine to lateral decubitus positioning at all levels. However, age, BMI, and gender had no statistically significant impact on the preoperative versus intraoperative corridor. Conclusion This is the first study to provide objective evidence that lateral decubitus positioning increases the intraoperative corridor for OLIF/ATP. Our study demonstrates that lateral decubitus positioning provides a more favorable corridor for the OLIF/ATP technique from L1-L5 disc levels.

External jugular venous sampling for Cushing's disease in a patient with hypoplastic inferior petrosal sinuses.

The authors report the case of a 30-year-old female patient with suspected Cushing's disease with an anatomical variation of hypoplastic inferior petrosal sinuses and nearly exclusive anterior drainage from the cavernous sinus, who underwent external jugular venous blood sampling with successful disease confirmation and microadenoma localization. The patient presented with signs and symptoms consistent with Cushing's syndrome, but with discordant preliminary diagnostic testing. She underwent attempted bilateral inferior petrosal sinus sampling; however, she had hypoplastic inferior petrosal sinuses bilaterally and predominantly anterior drainage from the cavernous sinus into the external jugular circulation. Given this finding, the decision was made to proceed with external jugular venous access and sampling in addition to internal jugular venous sampling. A positive adrenocorticotropic hormone (ACTH) response to corticotropin-releasing factor was obtained in the right external jugular vein alone, suggesting a right-sided pituitary microadenoma as the cause of her Cushing's disease. The patient subsequently underwent a transsphenoidal hypophysectomy that confirmed the presence of a right-sided ACTH-secreting microadenoma, which was successfully resected. She was hypocortisolemic on discharge and has had no signs of recurrence or relapse at 6 months postoperation.