Lo, Sheng-Fu Larry

BACKGROUND: Several collateral venous pathways exist to assist in cranial venous drainage in addition to the internal jugular veins. The important extrajugular networks (EJN) are often readily identified on diagnostic cerebral angiography. However, the angiographic pattern of venous drainage through collateral EJN has not been previously compared among patients with and without idiopathic intracranial hypertension (IIH). OBJECTIVE: To quantify EJN on cerebral angiography among patients both with and without IIH and to determine whether there is a different EJN venous drainage pattern in patients with IIH. METHODS: Retrospective imaging review of 100 cerebral angiograms (50 IIH and 50 non-IIH patients) and medical records from a single academic medical center was performed by 2 independent experienced neuroendovascular surgeons. Points were assigned to EJN flow from 0 to 6 using an increasing scale (with each patient's dominant internal jugular vein standardized to 5 points to serve as the internal reference). Angiography of each patient included 11 separately graded extrajugular networks for internal carotid and vertebral artery injections. RESULTS: Patients in the IIH group had statistically significant greater flow in several of the extrajugular networks. Therefore, they preferentially drained through EJN compared with the non-IIH group. Right transverse-sigmoid system was most often dominant in both groups, yet there was a significantly greater prevalence of codominant sinus pattern on posterior circulation angiograms. CONCLUSION: Patients with IIH have greater utilization of EJN compared with patients without IIH. Whether this is merely an epiphenomenon or possesses actual cause-effect relationships needs to be determined with further studies.

OBJECTIVE The Hospital Frailty Risk Score (HFRS) was developed utilizing ICD-10 diagnostic codes to identify frailty and predict adverse outcomes in large national databases. While other studies have examined frailty in spine oncology, the HFRS has not been assessed in this patient population. The aim of this study was to examine the association of HFRS-defined frailty with complication rates, length of stay (LOS), total cost of hospital admission, and discharge disposition in patients undergoing spine surgery for metastatic spinal column tumors. METHODS A retrospective cohort study was performed using the years 2016 to 2019 of the National Inpatient Sample (NIS) database. All adult patients (≥ 18 years old) undergoing surgical intervention for metastatic spinal column tumors were identified using the ICD-10-CM diagnostic codes and Procedural Coding System. Patients were categorized into the following three cohorts based on their HFRS: low frailty (HFRS < 5), intermediate frailty (HFRS 5–15), and high frailty (HFRS > 15). Patient demographics, comorbidities, treatment modality, perioperative complications, LOS, discharge disposition, and total cost of hospital admission were assessed. A multivariate logistic regression analysis was used to identify independent predictors of prolonged LOS, nonroutine discharge, and increased cost. RESULTS Of the 11,480 patients identified, 7085 (61.7%) were found to have low frailty, 4160 (36.2%) had intermediate frailty, and 235 (2.0%) had high frailty according to HFRS criteria. On average, age increased along with progressively worsening frailty scores (p ≤ 0.001). The proportion of patients in each cohort who experienced ≥ 1 postoperative complication significantly increased along with increasing frailty (low frailty: 29.2%; intermediate frailty: 53.8%; high frailty: 76.6%; p < 0.001). In addition, the mean LOS (low frailty: 7.9 ± 5.0 days; intermediate frailty: 14.4 ± 13.4 days; high frailty: 24.1 ± 18.6 days; p < 0.001), rate of nonroutine discharge (low frailty: 40.4%; intermediate frailty: 60.6%; high frailty: 70.2%; p < 0.001), and mean total cost of hospital admission (low frailty: $48,603 ± $29,979; intermediate frailty: $65,271 ± $43,110; high frailty: $96,116 ± $60,815; p < 0.001) each increased along with progressing frailty. On multivariate regression analysis, intermediate and high frailty were each found to be significant predictors of both prolonged LOS (intermediate: OR 3.75 [95% CI 2.96–4.75], p < 0.001; high: OR 7.33 [95% CI 3.47–15.51]; p < 0.001) and nonroutine discharge (intermediate: OR 2.05 [95% CI 1.68–2.51], p < 0.001; high: OR 5.06 [95% CI 1.93–13.30], p = 0.001). CONCLUSIONS This study is the first to use the HFRS to assess the impact of frailty on perioperative outcomes in patients with metastatic bony spinal tumors. Among patients with metastatic bony spinal tumors, frailty assessed using the HFRS was associated with longer hospitalizations, more nonroutine discharges, and higher total hospital costs.

Objective The Hospital Frailty Risk Score (HFRS) is a metric that measures frailty among patients in large national datasets using ICD-10 codes. While other metrics have been utilized to demonstrate the association between frailty and poor outcomes in spine oncology, none have examined the HFRS. The aim of this study was to investigate the impact of frailty using the HFRS on complications, length of stay, cost of admission, and discharge disposition in patients undergoing surgery for primary tumors of the spinal cord and meninges. Methods A retrospective cohort study was performed using the Nationwide Inpatient Sample database from 2016 to 2018. Adult patients undergoing surgery for primary tumors of the spinal cord and meninges were identified using ICD-10-CM codes. Patients were categorized into 2 cohorts based on HFRS score: Non-Frail (HFRS<5) and Frail (HFRS≥5). Patient characteristics, treatment, perioperative complications, LOS, discharge disposition, and cost of admission were assessed. Results Of the 5955 patients identified, 1260 (21.2%) were Frail. On average, the Frail cohort was nearly 8 years older ( P < .001) and experienced more postoperative complications ( P = .001). The Frail cohort experienced longer LOS ( P < .001), a higher rate of non-routine discharge ( P = .001), and a greater mean cost of admission ( P < .001). Frailty was found to be an independent predictor of extended LOS ( P < .001) and non-routine discharge ( P < .001). Conclusion Our study is the first to use the HFRS to assess the impact of frailty on patients with primary spinal tumors. We found that frailty was associated with prolonged LOS, non-routine discharge, and increased hospital costs.

Abstract BACKGROUND Total en bloc sacrectomy provides the best long-term local control for large primary bony sacral tumors, but often requires lumbosacral nerve root sacrifice leading to loss of ambulation and/or bowel, bladder, and/or sexual dysfunction. Nerve-sparing techniques may be an option for some patients that avoid these outcomes and accordingly improve postoperative quality of life. OBJECTIVE To describe the technique for a posterior-only en bloc hemisacrectomy with maximal nerve root preservation and to summarize the available literature. METHODS A 38-yr-old woman with a 7.7 × 5.4 × 4.5 cm biopsy-proven grade 2 chondrosarcoma involving the left L5-S2 posterior elements underwent a posterior-only left hemisacrectomy tri-rod L3-pelvis fusion. A systematic review of the English literature was also conducted to identify other descriptions of high sacrectomy with distal sacral nerve root preservation. RESULTS Computer-aided navigation facilitated an extracapsular resection that allowed preservation of the left-sided L5 and S3-Co roots. Negative margins were achieved and postoperatively the patient retained ambulation and good bowel/bladder function. Imaging at 9-mo follow-up showed no evidence of recurrence. The systematic review identified 4 prior publications describing 6 total patients who underwent nerve-sparing sacral resection. Enneking-appropriate resection was only obtained in 1 case though. CONCLUSION Here we describe a technique for distal sacral nerve root preservation during en bloc hemisacrectomy for a primary sacral tumor. Few prior descriptions exist, and the present technique may help to reduce the neurological morbidity of sacral tumor surgery.

Study Design International survey. Objectives To assess variability in the treatment practices for spinal metastases as a function of practice setting, surgical specialty, and fellowship training among an international group of spine surgeons. Methods An anonymous internet-based survey was disseminated to the AO Spine membership. The questionnaire contained items on practice settings, fellowship training, indications used for spinal metastasis surgery, surgical strategies, multidisciplinary team use, and postoperative follow-up priorities and practice. Results 341 gave complete responses to the survey with 76.3% identifying spinal oncology as a practice focus and 95.6% treating spinal metastases. 80% use the Spinal Instability Neoplastic Score (SINS) to guide instrumentation decision-making and 60.7% recruit multidisciplinary teams for some or all cases. Priorities for postoperative follow-up are adjuvant radiotherapy (80.9%) and systemic therapy (74.8%). Most schedule first follow-up within 6 weeks of surgery (62.2%). Significant response heterogeneity was seen when stratifying by practice in an academic or university-affiliated center, practice in a cancer center, completion of a spine oncology fellowship, and self-identification as a tumor specialist. Respondents belonging to any of these categories were more likely to utilize SINS ( P < .01-.02), recruit assistance from plastic surgeons (all P < .01), and incorporate radiation oncologists in postoperative care ( P < .01-.03). Conclusions The largest variability in practice strategies is based upon practice setting, spine tumor specialization, and completion of a spine oncology fellowship. These respondents were more likely to use evidenced-based practices. However, the response variability indicates the need for consensus building, particularly for postoperative spine metastasis care pathways and multidisciplinary team use.

OBJECTIVE High-grade spinal glioma (HGSG) is a rare but aggressive tumor that occurs in both adults and children. Histone H3 K27M mutation correlates with poor prognosis in children with diffuse midline glioma. However, the role of H3 K27M mutation in the prognosis of adults with HGSG remains unclear owing to the rarity of this mutation, conflicting reports, and the absence of multicenter studies on this topic. METHODS The authors studied a cohort of 30 adult patients with diffuse HGSG who underwent histological confirmation of diagnosis, surgical intervention, and treatment between January 2000 and July 2020 at six tertiary academic centers. The primary outcome was the effect of H3 K27M mutation status on progression-free survival (PFS) and overall survival (OS). RESULTS Thirty patients (18 males and 12 females) with a median (range) age of 50.5 (19–76) years were included in the analysis. Eighteen patients had H3 K27M mutation–positive tumors, and 12 had H3 K27M mutation–negative tumors. The median (interquartile range) PFS was 3 (10) months, and the median (interquartile range) OS was 9 (23) months. The factors associated with increased survival were treatment with concurrent chemotherapy/radiation (p = 0.006 for PFS, and p ≤ 0.001 for OS) and American Spinal Injury Association grade C or better at presentation (p = 0.043 for PFS, and p < 0.001 for OS). There were no significant differences in outcomes based on tumor location, extent of resection, sex, or H3 K27M mutation status. Analysis restricted to HGSG containing necrosis and/or microvascular proliferation (WHO grade IV histological features) revealed increased OS for patients with H3 K27M mutation–positive tumors (p = 0.017). CONCLUSIONS Although H3 K27M mutant–positive HGSG was associated with poor outcomes in adult patients, the outcomes of patients with H3 K27M mutant–positive HGSG were somewhat more favorable compared with those of their H3 K27M mutant–negative HGSG counterparts. Further preclinical animal studies and larger clinical studies are needed to further understand the age-dependent effects of H3 K27M mutation.

Abstract Background Chordomas are the most common primary spinal column malignancy in the United States. The aim of this study was to determine whether chordomas may be detected by evaluating mutations in circulating tumor DNA (ctDNA). Methods Thirty-two patients with a biopsy-confirmed diagnosis of chordoma had blood drawn pre-operatively and/or at follow-up appointments. Mutations in the primary tumor were identified by whole exome sequencing and liquid biopsy by ddPCR and/or RACE-Seq was used to detect one or more of these mutations in plasma ctDNA at concurrent or later time points. Results At the time of initial blood draw, 87.1% of patients were ctDNA positive (P &lt;.001). Follow-up blood draws in twenty of the patients suggest that ctDNA levels may reflect the clinical status of the disease. Patients with positive ctDNA levels were more likely to have greater mutant allele frequencies in their primary tumors (P = .004) and undergo radiotherapy (P = .02), and the presence of ctDNA may correlate with response to systemic chemotherapy and/or disease recurrence. Conclusions Detection of ctDNA mutations may allow for the detection and monitoring of disease progression for chordomas.

Abstract Background: Despite widespread use of femoral-sourced allografts in clinical spinal fusion procedures and the increasing interest in using femoral reamer–irrigator–aspirator (RIA) autograft in clinical bone grafting, few studies have examined the efficacy of femoral grafts compared to iliac crest grafts in spinal fusion. The objective of this study was to directly compare the use of autologous iliac crest with syngeneic femoral and iliac allograft bone in the rat model of lumbar spinal fusion.Methods: Single-level bilateral posterolateral intertransverse process lumbar spinal fusion surgery was performed on Lewis rats divided into three experimental groups: iliac crest autograft; syngeneic iliac crest allograft; and syngeneic femoral allograft bone. Eight weeks postoperatively, fusion was evaluated via microCT analysis, manual palpation and histology. In vitro analysis of the colony-forming and osteogenic capacity of bone marrow cells derived from rat femurs and hips was also performed to determine whether there was a correlation with the fusion efficacy of these graft sources.Results: Although no differences were observed between groups in CT fusion mass volumes, iliac allografts displayed an increased number of radiographically fused fusion masses and a higher rate of bilateral fusion via manual palpation. Histologically, hip-derived grafts showed better integration with host bone than femur derived ones, likely associated with the higher concentration of osteogenic progenitor cells observed in hip-derived bone marrow. Conclusions: This study demonstrates the feasibility of using syngeneic allograft bone in place of autograft bone within inbred rat fusion models and highlights the need for further study of femoral-derived grafts in fusion.

Abstract Background: Despite widespread use of femoral-sourced allografts in clinical spinal fusion procedures and the increasing interest in using femoral reamer–irrigator–aspirator (RIA) autograft in clinical bone grafting, few studies have examined the efficacy of femoral grafts compared to iliac crest grafts in spinal fusion. The objective of this study was to directly compare the use of autologous iliac crest with syngeneic femoral and iliac allograft bone in the rat model of lumbar spinal fusion.Methods: Single-level bilateral posterolateral intertransverse process lumbar spinal fusion surgery was performed on Lewis rats divided into three experimental groups: iliac crest autograft; syngeneic iliac crest allograft; and syngeneic femoral allograft bone. Eight weeks postoperatively, fusion was evaluated via microCT analysis, manual palpation and histology. In vitro analysis of the colony-forming and osteogenic capacity of bone marrow cells derived from rat femurs and hips was also performed to determine whether there was a correlation with the fusion efficacy of these graft sources.Results: Although no differences were observed between groups in CT fusion rates or fusion mass volumes, iliac allografts displayed a higher rate of bilateral fusion via manual palpation. Histologically, hip-derived grafts showed better integration with host bone than femur derived ones, likely associated with the higher concentration of osteogenic progenitor cells observed in hip-derived bone marrow.Conclusions: This study demonstrates the feasibility of using syngeneic allograft bone in place of autograft bone within inbred rat fusion models and highlights the need for further study of femoral-derived grafts in fusion.

Background: Local, intrawound use of antibiotic powder, such as vancomycin and tobramycin, in spinal fusion surgery has become an increasingly common prophylactic measure in an attempt to reduce rates of postsurgical infection. However, the effects of localized antibiotic delivery on fusion remain unclear. The objective of this study was to examine the in vivo effects of intraoperative local delivery of 2 antibiotics commonly used in bone-grafting surgery on spinal fusion outcomes in a rat model. Methods: Single-level (L4-L5), bilateral posterolateral intertransverse process lumbar fusion surgery was performed on 60 female Lewis rats (6 to 8 weeks of age) using syngeneic iliac crest allograft mixed with clinical bone-graft substitute and varying concentrations of antibiotics (n = 12 each): (1) control without any antibiotics, (2) low-dose vancomycin (14.3 mg/kg), (3) high-dose vancomycin (71.5 mg/kg), (4) low-dose tobramycin (28.6 mg/kg), and (5) high-dose tobramycin (143 mg/kg). Eight weeks postoperatively, fusion was evaluated via micro-computed tomography (µCT), manual palpation, and histological analysis, with blinding to treatment group. In the µCT analysis, fusion-mass volumes were measured for each rat. Each spine specimen (L4-L5) was rated (manual palpation score) on a scale of 2 to 0 (2 = fused, 1 = partially fused, and 0 = non-fused). Results: The mean fusion-mass volume on µCT (mm 3 ) was as follows: control, 29.3 ± 6.2; low-dose vancomycin, 26.3 ± 8.9; high-dose vancomycin, 18.8 ± 7.9; low-dose tobramycin, 32.7 ± 9.0; and high-dose tobramycin, 43.8 ± 11.9 (control versus high-dose vancomycin, p < 0.05; and control versus high-dose tobramycin, p < 0.05). The mean manual palpation score for each group was as follows: control, 1.46 ± 0.58; low-dose vancomycin, 0.86 ± 0.87; high-dose vancomycin, 0.68 ± 0.62; low-dose tobramycin, 1.25 ± 0.71; and high-dose tobramycin, 1.32 ± 0.72 (control versus high-dose vancomycin, p < 0.05). The histological analyses demonstrated a similar trend with regard to spinal fusion volume. Conclusions: Intraoperative local application of vancomycin, particularly at a supraphysiological dosage, may have detrimental effects on fusion-mass formation. No inhibitory effect of tobramycin on fusion-mass formation was observed. Clinical Relevance: When spine surgeons decide to use intraoperative intrawound antibiotics in spinal fusion surgery, they should weigh the reduction in surgical site infection against a possible inhibitory effect on fusion.