Faculty Bibliography

BACKGROUND AND OBJECTIVES/OBJECTIVE:Spine surgery has advanced in concert with our deeper understanding of its elements. Narrowly focused bibliometric analyses have been conducted previously, but never on the entire corpus of the field. Using big data and bibliometrics, we appraised the entire corpus of spine surgery publications to study the evolution of the specialty as a scholarly field since 1900. METHODS:We queried Web of Science for all contents from 13 major publications dedicated to spine surgery. We next queried by topic [topic = (spine OR spinal OR vertebrae OR vertebral OR intervertebral OR disc OR disk)]; these results were filtered to include articles published by 49 other publications that were manually determined to contain pertinent articles. Articles, along with their metadata, were exported. Statistical and bibliometric analyses were performed using the Bibliometrix R package and various Python packages. RESULTS:Eighty-five thousand five hundred articles from 62 journals and 134 707 unique authors were identified. The annual growth rate of publications was 2.78%, with a surge after 1980, concurrent with the growth of specialized journals. International coauthorship, absent before 1970, increased exponentially with the formation of influential spine study groups. Reference publication year spectroscopy allowed us to identify 200 articles that comprise the historical roots of modern spine surgery and each of its subdisciplines. We mapped the emergence of new topics and saw a recent lexical evolution toward outcomes- and patient-centric terms. Female and minority coauthorship has increased since 1990, but remains low, and disparities across major publications persist. CONCLUSION/CONCLUSIONS:The field of spine surgery was borne from pioneering individuals who published their findings in a variety of journals. The renaissance of spine surgery has been powered by international collaboration and is increasingly outcomes focused. While spine surgery is gradually becoming more diverse, there is a clear need for further promotion and outreach to under-represented populations.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Stereotactic radiosurgery (SRS) of larger arteriovenous malformations (AVM) is associated with an elevated incidence of adverse radiation effects (ARE). To date, volume-response and dose-response models have been used to predict such effects. To understand radiological outcomes and their hemodynamic effects on the regional brain. METHODS:A retrospective analysis was conducted at our institution using a prospective registry of patients managed between 2014 and 2020. We included patients with AVM with a nidus larger than 5 cc who received either single-session or volume-staged Gamma Knife radiosurgery. AVM volume changes, volumes of parenchymal response, and obliteration were analyzed and correlated with transit times and diameters of feeding arteries and draining veins. RESULTS:Sixteen patients underwent single-session SRS, and 9 patients underwent volume-staged SRS. The average AVM volume was 12.6 cc (5.5-23). The AVM locations were predominantly lobar (80%) and 17 (68%) were in critical locations. The mean margin dose was 17.2 Gy (15-21), and the median V12Gy was 25.5 cc. Fourteen (56%) AVMs had a transit time shorter than 1 second. The median vein-artery ratio (sum diameter of the veins/sum diameter of feeding arteries) was 1.63 (range, 0.60-4.19). Asymptomatic parenchymal effects were detected in 13 (52%) patients and were symptomatic in 4 (16%) patients. The median time to ARE was 12 months (95% CI 7.6-16.4). On univariate analysis, significant predictors of ARE were lower vein-artery ratio (P = .024), longer transit time (P = .05), higher mean dose (P = .028), and higher D95 (P = .036). CONCLUSION/CONCLUSIONS:Transit times and vessel diameters are valuable predictors of the subsequent parenchymal response after SRS. A more quantitative understanding of blood flow is critical for predicting the effects on the regional brain after AVM radiosurgery.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Advances in targeted therapies and wider application of stereotactic radiosurgery (SRS) have redefined outcomes of patients with brain metastases. Under modern treatment paradigms, there remains limited characterization of which aspects of disease drive demise and in what frequencies. This study aims to characterize the primary causes of terminal decline and evaluate differences in underlying intracranial tumor dynamics in patients with metastatic brain cancer. These fundamental details may help guide management, patient counseling, and research priorities. METHODS:Using NYUMets-Brain-the largest, longitudinal, real-world, open data set of patients with brain metastases-patients treated at New York University Langone Health between 2012 and 2021 with SRS were evaluated. A review of electronic health records allowed for the determination of a primary cause of death in patients who died during the study period. Causes were classified in mutually exclusive, but collectively exhaustive, categories. Multilevel models evaluated for differences in dynamics of intracranial tumors, including changes in volume and number. RESULTS:Of 439 patients with end-of-life data, 73.1% died secondary to systemic disease, 10.3% died secondary to central nervous system (CNS) disease, and 16.6% died because of other causes. CNS deaths were driven by acute increases in intracranial pressure (11%), development of focal neurological deficits (18%), treatment-resistant seizures (11%), and global decline driven by increased intracranial tumor burden (60%). Rate of influx of new intracranial tumors was almost twice as high in patients who died compared with those who survived (P < .001), but there was no difference in rates of volume change per intracranial tumor (P = .95). CONCLUSION/CONCLUSIONS:Most patients with brain metastases die secondary to systemic disease progression. For patients who die because of neurological disease, tumor dynamics and cause of death mechanisms indicate that the primary driver of decline for many may be unchecked systemic disease with unrelenting spread of new tumors to the CNS rather than failure of local growth control.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Meningiomas in children are uncommon, with distinct characteristics that set them apart from their adult counterparts. The existing evidence for stereotactic radiosurgery (SRS) in this patient population is limited to only case series. The objective of this study was to evaluate the safety and efficacy of SRS in managing pediatric meningiomas. METHODS:Children and adolescents who had been treated for meningioma with single-fraction SRS were included in this retrospective, multicenter study. The assessment included local tumor control, any complications related to the tumor or SRS, and the emergence of new neurological deficits after SRS. RESULTS:The cohort included 57 patients (male-to-female ratio 1.6:1) with a mean age of 14.4 years who were managed with single-fraction SRS for 78 meningiomas. The median radiological and clinical follow-up periods were 69 months (range, 6-268) and 71 months (range, 6-268), respectively. At the last follow-up, tumor control (tumor stability and regression) was achieved in 69 (85.9%) tumors. Post-SRS, new neurological deficits occurred in 2 (3.5%) patients. Adverse radiation effects occurred in 5 (8.8%) patients. A de novo aneurysm was observed in a patient 69 months after SRS. CONCLUSION/CONCLUSIONS:SRS seems to be a safe and effective up-front or adjuvant treatment option for surgically inaccessible, recurrent, or residual pediatric meningiomas.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Dose selection for brain metastases stereotactic radiosurgery (SRS) classically has been based on tumor diameter with a reduction of dose in the settings of prior brain irradiation, larger tumor volumes, and critical brain location. However, retrospective series have shown local control rates to be suboptimal with reduced doses. We hypothesized that lower doses could be effective for specific tumor biologies with concomitant systemic therapies. This study aims to report the local control (LC) and toxicity when using low-dose SRS in the era of modern systemic therapy. METHODS:We reviewed 102 patients with 688 tumors managed between 2014 and 2021 who had low-margin dose radiosurgery, defined as ≤14 Gy. Tumor control was correlated with demographic, clinical, and dosimetric data. RESULTS:The main primary cancer types were lung in 48 (47.1%), breast in 31 (30.4%), melanoma in 8 (7.8%), and others in 15 patients (11.7%). The median tumor volume was 0.037cc (0.002-26.31 cm3), and the median margin dose was 14 Gy (range 10-14). The local failure (LF) cumulative incidence at 1 and 2 years was 6% and 12%, respectively. On competing risk regression analysis, larger volume, melanoma histology, and margin dose were predictors of LF. The 1-year and 2-year cumulative incidence of adverse radiation effects (ARE: an adverse imaging-defined response includes increased enhancement and peritumoral edema) was 0.8% and 2%. CONCLUSION/CONCLUSIONS:It is feasible to achieve acceptable LC in BMs with low-dose SRS. Volume, melanoma histology, and margin dose seem to be predictors for LF. The value of a low-dose approach may be in the management of patients with higher numbers of small or adjacent tumors with a history of whole brain radio therapy or multiple SRS sessions and in tumors in critical locations with the aim of LC and preservation of neurological function.

BACKGROUND:Clival chordomas are challenging because of their proximity to critical neurovascular structures. Stereotactic radiosurgery (SRS) has been proven effective with minimal adverse effects. OBJECTIVE:To compare the outcomes of histologically confirmed primary clival chordomas in adults who underwent SRS alone (SRS group) vs SRS after fractionated radiotherapy (FRT+SRS group). METHODS:We collected patient data from 10 institutions affiliated with the International Radiosurgery Research Foundation. We evaluated overall survival, tumor control, and freedom from additional treatment (FFAT). RESULTS:Fifty-seven (77%) patients were included in the SRS group and 17 (23%) in the FRT+SRS group. The median radiological follow-up was 48 months (IQR, 24-85) in the SRS group and 36 months (IQR, 25-41) in the FRT+SRS group. During the follow-up, 8 SRS and 2 FRT+SRS patients died ( P = .80). The groups had comparable 10-year overall survival (SRS: 76% vs FRT+SRS: 80%; logrank test, P = .75) and tumor control rates (SRS: 34% vs FRT+SRS: 45%; logrank test, P = .29). The SRS group had a superior 10-year FFAT rate (40%) compared with FRT+SRS (23%; logrank test, P = .02). This finding persisted in the multivariate analysis of the Cox proportional hazards illustrating a 2.40-fold increase in the relative risk of requiring additional treatment among the FRT+SRS group ( P = .04). CONCLUSION:Adjuvant FRT with subsequent boost SRS did not provide superior overall survival or tumor control compared with patients who underwent adjuvant SRS alone. Further studies are required to refine management guidelines among adults with clival chordomas.

Over the past generation, outcome measures in spine care have evolved from a reliance on clinician-reported assessment toward recognizing the importance of the patient's perspective and the wide incorporation of patient-reported outcomes (PROs). While patient-reported outcomes are now considered an integral component of outcomes assessments, they cannot wholly capture the state of a patient's functionality. There is a clear need for quantitative and objective patient-centered outcome measures. The pervasiveness of smartphones and wearable devices in modern society, which passively collect data related to health, has ushered in a new era of spine care outcome measurement. The patterns emerging from these data, so-called "digital biomarkers," can accurately describe characteristics of a patient's health, disease, or recovery state. Broadly, the spine care community has thus far concentrated on digital biomarkers related to mobility, although the researcher's toolkit is anticipated to expand in concert with advancements in technology. In this review of the nascent literature, we describe the evolution of spine care outcome measurements, outline how digital biomarkers can supplement current clinician-driven and patient-driven measures, appraise the present and future of the field in the modern era, as well as discuss present limitations and areas for further study, with a focus on smartphones (see Supplemental Digital Content , http://links.lww.com/NEU/D809 , for a similar appraisal of wearable devices).

PURPOSE/OBJECTIVE:Approximately 80% of brain metastases originate from non-small cell lung cancer (NSCLC). Immune checkpoint inhibitors (ICI) and stereotactic radiosurgery (SRS) are frequently utilized in this setting. However, concerns remain regarding the risk of radiation necrosis (RN) when SRS and ICI are administered concurrently. METHODS:A retrospective study was conducted through the International Radiosurgery Research Foundation. Logistic regression models and competing risks analyses were utilized to identify predictors of any grade RN and symptomatic RN (SRN). RESULTS:was a significant predictor of developing any grade RN (OR: 2.18) and SRN (OR: 3.95). At 1-year, the cumulative incidence of any grade and SRN for all patients was 4.8% and 3.8%, respectively. For concurrent and non-concurrent groups, the cumulative incidence of any grade RN was 3.8% versus 5.3%, respectively (p = 0.35); and for SRN was 3.8% vs. 3.6%, respectively (p = 0.95). CONCLUSION/CONCLUSIONS:. Concurrent ICI and SRS do not appear to increase this risk. Radiosurgical planning techniques should aim to minimize V12 Gy.

OBJECTIVE:Stereotactic radiosurgery (SRS) has been proposed as an alternative to resection for epilepsy control in patients with cerebral cavernous malformations (CCM) located in critical areas. METHODS:This multicentric, retrospective study evaluated seizure control in patients with a solitary CCM and a history of at least one seizure prior to SRS. RESULTS:109 patients (median age at diagnosis 28.9 years, interquartile range (IQR) 16.4 years] were included. Prior to SRS, 2 (1.8%) were seizure-free without medication, 35 (32.1%) were seizure-free with antiseizure medications (ASM), 17 (15.6%) experienced an improvement of at least 50% in seizure frequency/intensity with ASM, and 55 (50.5%) experienced an improvement of less than 50% in seizure frequency/intensity with ASM. At a median follow-up of 3.5 years post-SRS (IQR: 4.9), 52 (47.7%) patients were Engel class I, 13 (11.9%) class II, 17 (15.6%) class III, 22 (20.2%) class IVA or IVB and 5 (4.6%) class IVC. For the 72 patients who had seizures despite medication prior to SRS, a delay > 1.5 years between epilepsy presentation and SRS decreased the probability to become seizure-free, HR 0.25 (95% CI 0.09-0.66), p = 0.006. The probability of achieving Engel I at the last follow-up was 23.6 (95% CI 12.7-33.1) and 31.3% (95% CI 19.3-50.8) at 2 and 5 years respectively. 27 patients were considered as having drug-resistant epilepsy. At a median follow-up of 3.1 years (IQR: 4.7), 6 (22.2%) of them were Engel I, 3 (11.1%) Engel II, 7 (25.9%) Engel III, 8 (29.6%) Engel IVA or IVB and 3 (11.1%) Engel IVC. INTERPRETATION/CONCLUSIONS:47.7% of patients managed with SRS for solitary CCM presenting with seizures achieved Engel class I at the last follow-up.