Multidisciplinary surgical considerations for en bloc resection of sacral chordoma: review of recent advances and a contemporary single-center series

OBJECTIVE

Contemporary management of sacral chordomas requires maximizing the potential for recurrence-free and overall survival while minimizing treatment morbidity. En bloc resection can be performed at various levels of the sacrum, with tumor location and volume ultimately dictating the necessary extent of resection and subsequent tissue reconstruction. Because tumor resection involving the upper sacrum may be quite destabilizing, other pertinent considerations relate to instrumentation and subsequent tissue reconstruction. The primary aim of this study was to survey the surgical approaches used for managing primary sacral chordoma according to location of lumbosacral spine involvement, including a narrative review of the literature and examination of the authors' institutional case series.

METHODS

The authors performed a narrative review of pertinent literature regarding reconstruction and complication avoidance techniques following en bloc resection of primary sacral tumors, supplemented by a contemporary series of 11 cases from their cohort. Relevant surgical anatomy, advances in instrumentation and reconstruction techniques, intraoperative imaging and navigation, soft-tissue reconstruction, and wound complication avoidance are also discussed.

RESULTS

The review of the literature identified several surgical approaches used for management of primary sacral chordoma localized to low sacral levels (mid-S2 and below), high sacral levels (involving upper S2 and above), and high sacral levels with lumbar involvement. In the contemporary case series, the majority of cases (8/11) presented as low sacral tumors that did not require instrumentation. A minority required more extensive instrumentation and reconstruction, with 2 tumors involving upper S2 and/or S1 levels and 1 tumor extending into the lower lumbar spine. En bloc resection was successfully achieved in 10 of 11 cases, with a colostomy required in 2 cases due to rectal involvement. All 11 cases underwent musculocutaneous flap wound closure by plastic surgery, with none experiencing wound complications requiring revision.

CONCLUSIONS

The modern management of sacral chordoma involves a multidisciplinary team of surgeons and intraoperative technologies to minimize surgical morbidity while optimizing oncological outcomes through en bloc resection. Most cases present with lower sacral tumors not requiring instrumentation, but stabilizing instrumentation and lumbosacral reconstruction are often required in upper sacral and lumbosacral cases. Among efforts to minimize wound-related complications, musculocutaneous flap closure stands out as an evidence-based measure that may mitigate risk.

Systematic Review of Prophylactic Plastic Surgery Closure to Prevent Postoperative Wound Complications Following Spine Surgery

Spinal surgeries are increasingly performed in the United States, but complication rates can be unacceptably high at up to 26%. Consequently, plastic surgeons (PS) are sometimes recruited by spine surgeons (SS) for intraoperative assistance with soft tissue closures. An electronic multidatabase literature search was systematically conducted to determine whether spinal wound closure performed by PS minimizes postoperative wound healing complications when compared to closure by SS (neurosurgical or orthopedic), with the hypothesis that closures by PS minimizes incidence of complications. All published studies involving patients who underwent posterior spinal surgery with closure by PS or SS at index spine surgery were identified. Filtering by exclusion criteria identified 10 studies, 4 of which were comparative in nature and included both closures by PS and SS. Of these 4, none reported significant differences in postoperative outcomes between the groups. Across all studies, PS were involved in cases with higher baseline risk for wound complications and greater comorbidity burden. Closures by PS were significantly more likely to have had prior chemotherapy in 2 of the 4 (50%) studies (P = 0.014, P < 0.001) and radiation in 3 of the 4 (75%) studies (P < 0.001, P < 0.01, P < 0.001). In conclusion, closures by PS are frequently performed in higher risk cases, and use of PS in these closures may normalize the risk of wound complications to that of the normal risk cohort, though the overall level of evidence of the published literature is low.

Clinical criteria for filum terminale resection in occult tethered cord syndrome

OBJECTIVE

Tethered cord syndrome (TCS) comprises three symptom categories: back/leg pain, bowel/bladder, and neurological complaints. MRI typically reveals a low-lying conus medullaris, filum terminale (FT) pathology, or lumbosacral abnormalities. FT resection is established in TCS but not in radiologically occult TCS (OTCS). This study aims to identify patients with OTCS who are likely to benefit from FT resection.

METHODS

The authors recruited 149 patients with OTCS (31 pediatric, 118 adult) treated with FT resection-including only cases with progressive TCS, negative spine MRI, and no concurrent neurological/urological conditions. A comprehensive questionnaire collected patient self-reported symptoms and clinical findings at the preoperative and at 3- and 12-month follow-up examinations. Based on questionnaire data, the authors extracted a 15-item symptoms and findings scale to represent the three TCS symptom categories, assigning 1 point for each item present.

RESULTS

OTCS presents without radicular/segmental sensorimotor findings, but with leg/back pain and conus dysfunction, in addition to leg fatigue and spasticity; the latter indicating an upper motoneuron pathology. The 15-item scale showed clinical improvement in 89% of patients at the 3-month follow-up and 68% at the 12-month follow-up. Multivariate analysis of the scale revealed that it accurately predicts outcome of FT resection in 82% of cases. Patients with a preoperative score exceeding 6 points are most likely to benefit from surgery.

CONCLUSIONS

By applying the study's inclusion criteria and incorporating the novel 15-item scale, surgeons can effectively select candidates for FT resection in patients with OTCS. The observed outcomes in these selected patients are comparable to those achieved in degenerative spine surgery.

Endoscopic Lateral Lumbar Interbody Fusion: Technical Note and Case Series

BACKGROUND

Our objective is to describe a minimally invasive endoscopic surgical technique for performing lateral lumbar interbody fusion (LLIF). LLIF is a common approach to lumbar fusion in cases of degenerative lumbar disease; however, complications associated with psoas and lumbar plexus injury sometimes arise. The endoscopic modification presented here diminishes the requirement for sustained muscle retraction, minimizing complication risk while allowing for adequate decompression in select cases.

METHODS

Endoscopic LLIF (ELLIF) was performed in 3 patients from 2019 to 2021. Surgeries were performed in the lateral position under general anesthesia with neurophysiological monitoring. Discectomy, endplate preparation, and harvesting of iliac crest bone were performed through a working channel endoscope. The introduction of an interbody cage (Joimax EndoLIF) was performed over a nitinol blunt-tip wire (Joimax). No expandable blade retractors were required.

RESULTS

At 2-year follow-up of these 3 patients, the mean visual analog scale (VAS) score for leg pain improved from 9.3 to 1.7, and the mean Oswestry Disability Index (ODI) score improved from 40 to 8.3. There were no complications, readmissions, or recurrence of symptoms during the 2-year follow-up period. Patients spent an average of 36 hours in the hospital postoperatively and returned to normal daily activities after an average of 48 days.

CONCLUSIONS

A minimally invasive modification to the LLIF procedure is presented that offers several potential advantages due to the application of endoscopic techniques: reduced muscle retraction, smaller incision, and the opportunity to perform both indirect decompression and endoscopically visualized discectomy in the same fusion procedure.

CLINICAL RELEVANCE

The proposed endoscopic lateral lumbar interbody fusion and decompression is a minimally invasive technique that may provide patients with minimal complications, quick recovery, and good functional recovery.

LEVEL OF EVIDENCE: 4

Short-Term Pain Outcomes and Pain Medication Utilization Among Urine Toxicology-Identified Opioid and Marijuana Users After Elective Spine Surgery

BACKGROUND AND OBJECTIVES

Postoperative pain outcomes may be influenced by preoperative substance use, which is often underreported due to associated stigma. This study examined the impact of urine toxicology-identified preoperative opioid and marijuana use on pain outcomes after elective spinal surgery.

METHODS

Patients undergoing elective spinal surgery between September 2020 and May 2022 were recruited for this prospective cohort study. Detailed chart review was completed to collect demographic, urine toxicology, Visual Analog Scale (VAS), and pain medication data. Comparisons between self-reported and urine toxicology-identified substance use, preoperative/postoperative VAS ratings, and postoperative pain medication use were made using χ 2 tests, Student t -tests, and logistic regression, respectively. Models were adjusted for age, sex, and race.

RESULTS

Among 111 participants (mean age 58 years, 59% female, 95% with ≥1 comorbidity), urine toxicology overestimated drug use (47% vs 16%, P < .001) and underestimated alcohol use (16% vs 56%, P < .001) at preoperative baseline relative to patient reports. Two weeks postoperatively, participants with preoperative opioid metabolites reported no significant improvements in pain from baseline (6.67 preoperative vs 5.92 postoperative, P = .288) unlike nonusers (6.56 preoperative vs 4.61 postoperative, P < .001). They also had worse postoperative VAS (5.92 vs 4.61, P = .030) and heavier reliance on opioid medications (odds ratio = 3.09, 95% CI = 1.21-7.89, P = .019). Conversely, participants with preoperative marijuana reported similar improvements in pain from baseline (users: 6.88 preoperative vs 4.36 postoperative, P = .001; nonusers: 6.49 preoperative vs 5.07 postoperative, P = .001), similar postoperative pain (4.36 vs 5.07, P = .238), and similar postoperative reliance on opioid medications (odds ratio = 0.96, 95% CI = 0.38-2.44, P = .928). Trends were maintained among the 83 patients who returned for the 3-month follow-up.

CONCLUSION

Although urine toxicology-identified preoperative opioid use was associated with poor postoperative pain relief and reliance on postoperative opioids for pain management after elective spinal surgery, preoperative marijuana use was not. Preoperative marijuana use, hence, should not delay or be a contraindication to elective spinal surgery.

Trends in engagement with cognitive-behavioral therapy for chronic pain conditions after referral

Cognitive-behavioral therapy for chronic pain (CBT-CP) is an important evidence-based non-pharmacologic treatment for chronic back and neck pain that is frequently recommended as a component of multidisciplinary treatment. However, the success of CBP-CP's implementation in clinical settings is affected by a variety of poorly understood obstacles to patient engagement with CBT-CP. Expanding upon the limited prior research conducted in heterogeneous practice settings, this study examines patterns of treatment initiation for CBT-CP at an interdisciplinary, hospital-based chronic pain practice and conducts exploratory comparisons between groups of patients who did and did not engage in CBT-CP after receiving a referral. Patients' descriptive data, including pain severity, work status, prior therapy, and behavioral health questionnaire scores at intake visit, were obtained through a retrospective chart review of electronic medical records. Data were then analyzed using inter-group comparisons and logistic regression modeling to determine factors that predicted treatment initiation for CBT-CP. On multivariate analysis, we found that patient's depression level as measured by their Patient Health Questionnaire 9 (PHQ-9) score was solely predictive of treatment initiation, as chronic pain patients with a higher level of depression were found to be more likely to attend their recommended appointments of CBT-CP. Anxiety score as measured by GAD-7, work status, pain scores, and prior therapy engagement were not independently predictive. No single "profile" of patient-level factors was found to delineate patients who did and did not initiate CBT-CP, demonstrating the limitations of clinical variables as predictors of uptake.

Disparities in Primary Spinal Osseous Malignant Bone Tumor Survival by Medicaid Status: A National Population-Based Risk Analysis

BACKGROUND

The impact of Medicaid status on survival outcomes of patients with spinal primary malignant bone tumors (sPMBT) has not been investigated.

METHODS

Using the SEER-Medicaid database, adults diagnosed between 2006 and 2013 with sPMBT including chordoma, osteosarcoma, chondrosarcoma, Ewing sarcoma, or malignant giant cell tumor (GCT) were studied. Five-year survival analysis was performed using the Kaplan-Meier method. Adjusted survival analysis was performed using Cox proportional-hazards regression controlling for age, sex, marital status, cancer stage, poverty level, vertebral versus sacral location, geography, rurality, tumor diameter, tumor grade, tumor histology, and therapy.

RESULTS

A total of 572 patients with sPMBT (Medicaid: 59, non-Medicaid: 513) were identified. Medicaid patients were more likely to be younger (P < 0.001), Black (P < 0.001), live in high poverty neighborhoods (P = 0.006), have distant metastases at diagnosis (P < 0.001), and less likely to receive surgery (P = 0.006). The 5-year survival rate was 65.7% (chondrosarcoma: 70.0%, chordoma: 91.5%, Ewing sarcoma: 44.6%, GCT: 90.0%, osteosarcoma: 34.2%). Medicaid patients had significantly worse 5-year survival than non-Medicaid patients (52.0% vs. 67.2%, P = 0.02). Minority individuals on Medicaid were associated with an increased risk of cancer-specific mortality compared with White non-Medicaid patients (adjusted hazard ratio [aHR] = 2.51, [95% CI 1.18-5.35], P = 0.017). Among Medicaid patients, those who received surgery had significantly better survival than those who did not (64.5% vs. 30.6%, P = 0.001). For all patients, not receiving surgery (aHR = 1.90 [1.23-2.95], P = 0.004) and tumor diameter >50 mm (aHR=1.89 [1.10-3.25], P = 0.023) were associated with an increased risk of mortality.

CONCLUSIONS

Medicaid patients may be less likely to receive surgery and suffer from poorer survival. These disparities may be especially prominent among minorities.

The Surgical Histopathology of the Filum Terminale: Findings from a Large Series of Patients with Tethered Cord Syndrome

This study investigated the prevalence of embryonic and connective tissue elements in the filum terminale (FT) of patients with tethered cord syndrome (TCS), examining both typical and pathological histology. The FT specimens from 288 patients who underwent spinal cord detethering from 2013 to 2021 were analyzed. The histopathological examination involved routine hematoxylin and eosin staining and specific immunohistochemistry when needed. The patient details were extracted from electronic medical records. The study found that 97.6% of the FT specimens had peripheral nerves, and 70.8% had regular ependymal cell linings. Other findings included ependymal cysts and canals, ganglion cells, neuropil, and prominent vascular features. Notably, 41% showed fatty infiltration, and 7.6% had dystrophic calcification. Inflammatory infiltrates, an underreported finding, were observed in 3.8% of the specimens. The research highlights peripheral nerves and ganglion cells as natural components of the FT, with ependymal cell overgrowth and other tissues potentially linked to TCS. Enlarged vessels may suggest venous congestion due to altered FT mechanics. The presence of lymphocytic infiltrations and calcifications provides new insights into structural changes and mechanical stress in the FT, contributing to our understanding of TCS pathology.

Optimizing surgical management of facet cysts of the lumbar spine: systematic review, meta-analysis, and local case series of 1251 patients

OBJECTIVE

Lumbar facet cysts (LFCs) can cause neurological dysfunction and intractable pain. Surgery is the current standard of care for patients in whom conservative therapy fails, those with neurological deficits, and those with evidence of spinal instability. No study to date has comprehensively examined surgical outcomes comparing the multiple surgical treatment options for LFCs. Therefore, the authors aimed to perform a combined analysis of cases both in the literature and of patients at a single institution to compare the outcomes of various surgical treatment options for LFC.

METHODS

The authors performed a literature review in accordance with PRISMA guidelines and meta-analysis of the PubMed, Embase, and Cochrane Library databases and reviewed all studies from database inception published until February 3, 2023. Studies that did not contain 3 or more cases, clearly specify follow-up durations longer than 6 months, or present new cases were excluded. Bias was evaluated using Cochrane Collaboration's Risk of Bias in Nonrandomised Studies-of Interventions (ROBINS-I). The authors also reviewed their own local institutional case series from 2015 to 2020. Primary outcomes were same-level cyst recurrence, same-level revision surgery, and perioperative complications. ANOVA, common and random-effects modeling, and Wald testing were used to compare treatment groups.

RESULTS

A total of 1251 patients were identified from both the published literature (29 articles, n = 1143) and the authors' institution (n = 108). Patients were sorted into 5 treatment groups: open cyst resection (OCR; n = 720), tubular cyst resection (TCR; n = 166), cyst resection with arthrodesis (CRA; n = 165), endoscopic cyst resection (ECR; n = 113), and percutaneous cyst rupture (PCR; n = 87), with OCR being the analysis reference group. The PCR group had significantly lower complication rates (p = 0.004), higher recurrence rates (p < 0.001), and higher revision surgery rates (p = 0.001) compared with the OCR group. Patients receiving TCR (3.01%, p = 0.021) and CRA (0.0%, p < 0.001) had significantly lower recurrence rates compared with those undergoing OCR (6.36%). The CRA group (6.67%) also had significantly lower rates of revision surgery compared with the OCR group (11.3%, p = 0.037).

CONCLUSIONS

While PCR is less invasive, it may have high rates of same-level recurrence and revision surgery. Recurrence and revision rates for modalities such as ECR were not significantly different from those of OCR. While concomitant arthrodesis is more invasive, it might lead to lower recurrence rates and lower rates of subsequent revision surgery. Given the limitations of our case series and literature review, prospective, randomized studies are needed.

A decade of diversity: using statistical indices to compare neurosurgery to other surgical specialties

OBJECTIVE

Studies have demonstrated the benefits of diversity in neurosurgery. However, recruitment of minoritized groups within the neurosurgical workforce consistently lags other surgical specialties. While racial and gender demographics of neurosurgical residents are well documented, there has been minimal exploration into the multidimensional nature of diversity. The current study will evaluate the longitudinal diversity changes in neurosurgery residency programs compared with other surgical fields with validated diversity indices.

METHODS

Nationwide reports including data about resident physicians were obtained from the American Medical Association and the Association of American Medical Colleges for the academic years 2008-2021. Self-reported race, biological sex, and medical school affiliation were recorded for surgical residents in the 10 commonly recognized surgical fields. The Gini-Simpson Diversity Index was used to calculate the effective counts (ECs) of races, sexes, and medical school types for each field. A Composite Diversity Index (CDI) comprising the aforementioned diversity traits was used to calculate the percentage of characteristics upon which two randomly selected residents within each specialty would differ. CDIs were calculated for each field in every year from 2008 to 2021. Median CDIs were compared between fields using Kruskal-Wallis testing, and p values < 0.05 were deemed statistically significant.

RESULTS

Plastic surgery had the highest median sex EC (1.92, interquartile range [IQR] 1.78-1.95), indicating greater diversity, while neurosurgery had the third lowest sex EC (1.40, IQR 1.35-1.41). All surgical fields examined had fewer than 3 races effectively represented among their residents, despite there being 8 races present. Neurosurgery ranked among the top fields in effective racial diversity (EC 2.17, IQR 2.09-2.21) and medical school type diversity (EC 1.25, IQR 1.21-1.26). There were statistically significant differences in the sex, race, and school ECs between surgical specialties. While neurosurgery had a relatively low median overall diversity (CDI = 32.7, IQR 32.0-34.6), there was a consistent longitudinal increase in CDI from 2015 to 2021.

CONCLUSIONS

Neurosurgery resident physicians have become increasingly diverse in the past decade but are more homogenous than residents in other surgical fields. The continued use of diversity indices to more accurately track diversity progress over time may better inform leaders in the field of how they may best focus their equity and inclusion efforts.

Cerebrospinal fluid transcripts may predict shunt surgery responses in normal pressure hydrocephalus

Molecular biomarkers for neurodegenerative diseases are critical for advancing diagnosis and therapy. Normal pressure hydrocephalus (NPH) is a neurological disorder characterized by progressive neurodegeneration, gait impairment, urinary incontinence and cognitive decline. In contrast to most other neurodegenerative disorders, NPH symptoms can be improved by the placement of a ventricular shunt that drains excess CSF. A major challenge in NPH management is the identification of patients who benefit from shunt surgery. Here, we perform genome-wide RNA sequencing of extracellular vesicles in CSF of 42 NPH patients, and we identify genes and pathways whose expression levels correlate with gait, urinary or cognitive symptom improvement after shunt surgery. We describe a machine learning algorithm trained on these gene expression profiles to predict shunt surgery response with high accuracy. The transcriptomic signatures we identified may have important implications for improving NPH diagnosis and treatment and for understanding disease aetiology.

Early Signs of Elevated Intracranial Pressure on Computed Tomography Correlate With Measured Intracranial Pressure in the Intensive Care Unit and Six-Month Outcome After Moderate to Severe Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability in the United States. Early triage and treatment after TBI have been shown to improve outcome. Identifying patients at risk for increased intracranial pressure (ICP) via baseline computed tomography (CT) , however, has not been validated previously in a prospective dataset. We hypothesized that acute CT findings of elevated ICP, combined with direct ICP measurement, hold prognostic value in terms of six-month patient outcome after TBI. Data were obtained from the Progesterone for Traumatic Brain Injury, Experimental Clinical Treatment (ProTECTIII) multi-center clinical trial. Baseline CT scans for 881 participants were individually reviewed by a blinded central neuroradiologist. Five signs of elevated ICP were measured (sulcal obliteration, lateral ventricle compression, third ventricle compression, midline shift, and herniation). Associations between signs of increased ICP and outcomes (six-month functional outcome and death) were assessed. Secondary analyses of 354 patients with recorded ICP monitoring data available explored the relationships between hemorrhage phenotype/anatomic location, sustained ICP ≥20 mm Hg, and surgical intervention(s). Univariate and multi-variate logistic/linear regressions were performed; p < 0.05 is defined as statistically significant. Imaging characteristics associated with ICP in this cohort include sulcal obliteration (p = 0.029) and third ventricular compression (p = 0.039). Univariate regression analyses indicated that increasing combinations of the five defined signs of elevated ICP were associated with death, poor functional outcome, and time to death. There was also an increased likelihood of death if patients required craniotomy (odds ratio [OR] = 4.318, 95% confidence interval [1.330-16.030]) or hemicraniectomy (OR = 2.993 [1.109-8.482]). On multi-variate regression analyses, hemorrhage location was associated with death (posterior fossa, OR = 3.208 [1.120-9.188] and basal ganglia, OR = 3.079 [1.178-8.077]). Volume of hemorrhage >30 cc was also associated with increased death, OR = 3.702 [1.575-8.956]). The proportion of patient hours with sustained ICP ≥20 mm Hg, and maximum ICP ≥20 mm Hg were also directly correlated with increased death (OR = 6 4.99 [7.731-635.51]; and OR = 1.025 [1.004-1.047]), but not with functional outcome. Poor functional outcome was predicted by concurrent presence of all five radiographic signs of elevated ICP (OR = 4.44 [1.514-14.183]) and presence of frontal lobe (OR = 2.951 [1.265-7.067]), subarachnoid (OR = 2.231 [1.067-4.717]), or intraventricular (OR = 2.249 [1.159-4.508]) hemorrhage. Time to death was modulated by total patient days of elevated ICP ≥20 mm Hg (effect size = 3.424 [1.500, 5.439]) in the first two weeks of hospitalization. Sulcal obliteration and third ventricular compression, radiographic signs of elevated ICP, were significantly associated with measurements of ICP ≥20 mm Hg. These radiographic biomarkers were significantly associated with patient outcome. There is potential utility of ICP-related imaging variables in triage and prognostication for patients after moderate-severe TBI.

Continued underrepresentation of historically excluded groups in the neurosurgery pipeline: an analysis of racial and ethnic trends across stages of medical training from 2012 to 2020

OBJECTIVE

US allopathic medical schools have experienced improvements in racial and ethnic diversity among matriculants in the past decade. It is not clear, however, whether better representation of historically excluded racial and ethnic groups at medical school entry impacts subsequent stages of the medical training pipeline leading into a specific field. The aim of this study was to examine these trends as they relate to the neurosurgical medical education pipeline and consider the drivers that sustain barriers for underrepresented groups.

METHODS

Race and ethnicity reports from the American Association of Medical Colleges were obtained on allopathic medical school applicants, acceptees, and graduates and applicants to US neurosurgical residency programs from 2012 to 2020. The representation of groups categorized by self-reported race and ethnicity was compared with their US population counterparts to determine the representation quotient (RQ) for each group. Annual racial composition differences and changes in representation over time at each stage of medical training were evaluated by estimating incidence rate ratios (IRRs) and 95% confidence intervals (CIs) using non-Hispanic Whites as the reference group.

RESULTS

On average, Asian and White individuals most frequently applied and were accepted to medical school, had the highest graduation rates, and applied to neurosurgery residency programs more often than other racial groups. The medical school application and acceptance rates for Black individuals increased from 2012 to 2020 relative to Whites by 30% (95% CI 1.23-1.36) and 42% (95% CI 1.31-1.53), respectively. During this same period, however, inequities in neurosurgical residency applications grew across all non-Asian racialized groups relative to Whites. While the incidence of active Black neurosurgery residents increased from 2012 to 2020 (0.6 to 0.7/100,000 Black US inhabitants), the prevalence of White neurosurgery residents grew in the active neurosurgery resident population by 16% more.

CONCLUSIONS

The increased racial diversity of medical school students in recent years is not yet reflected in racial representation among neurosurgery applicants. Disproportionately fewer Black relative to White US medical students apply to neurosurgery residency, which contributes to declining racial representation among all active neurosurgery resident physicians. Hispanic individuals are becoming increasingly represented in neurosurgery residency but continue to remain underrepresented relative to the US population. Ongoing efforts to recruit medical students into neurosurgery who more accurately reflect the diversity of the general US population are necessary to ensure equitable patient care.

Charlson comorbidity index applied to shunted idiopathic normal pressure hydrocephalus

A series of epidemiological studies have shown the limited life expectancy of patients suffering from idiopathic normal pressure hydrocephalus (iNPH). In most cases, comorbid medical conditions are the cause of death, rather than iNPH. Though it has also been shown that shunting improves both life quality and lifetime. We sought to investigate the utility of the Charlson comorbidity index (CCI) for improved preoperative risk-benefit assessment of shunt surgery in individual iNPH cases. 208 shunted iNPH cases were prospectively investigated. Two in-person follow up visits at 3 and 12 months assessed postoperative clinical status. The correlation of the age adjusted CCI with survival was investigated over the median observation time of 2.37 years (IQR 1.16-4.15). Kaplan Meier statistics revealed that patients with a CCI score of 0-5 have a 5-year survival rate of 87%, compared to only 55% in patients with CCI > 5. Cox multivariate statistics revealed that the CCI was an independent predictor of survival, while common preoperative iNPH scores (modified Rankin Scale (mRS), gait score, and continence score) are not. As expected, mRS, gait, and continence scores improved during the postoperative follow up period, though relative improvement on any of these was not predicted by baseline CCI. The CCI is an easily applicable preoperative predictor of survival time in shunted iNPH patients. The lack of a correlation between the CCI and functional outcome means that even patients with multiple comorbidities and limited remaining lifetime may appreciate benefit from shunt surgery.

Reappraisal of intradural findings in Chiari malformation type I

OBJECTIVE

Management of Chiari malformation type I (CM-I) requires the functional restoration of an obstructed cisterna magna. In posterior fossa decompression with duraplasty (PFDD), various intradural pathologies are suggested to alter CSF flow at the craniocervical junction and require surgical correction. However, reports of the spectrum of intraoperative intradural findings and their nuances are scarce, especially those characterizing rarer findings pertaining to the vascular structures and vascular compression.

METHODS

The authors conducted a retrospective cohort analysis of adults and children who underwent first-time PFDD for CM-I (2011-2021), with and without syringomyelia. The surgical reports and intraoperative videos were reviewed, and the frequency and nature of the intradural observations in regard to the tonsils, arachnoid, and vasculature were analyzed along with the clinical findings and surgical outcomes.

RESULTS

All 180 patients (age range 1-72 years; median [interquartile range] 24 (14-38) years; 37% of patients were children < 21 years of age) exhibited multiple intradural findings, with a median of 7 distinct concurrent observations in each patient. Novel findings not previously reported included posterior inferior communicating artery (PICA) branches compressing the neural elements at the cervicomedullary junction (26.7%). Other common findings included arachnoid adhesions (92.8%), thickening (90.6%), webs at the obex (52.2%), tonsillar gliosis (57.2%), tonsillar hypertrophy (18.3%), adhesions obstructing the foramen of Magendie (FoM) (62.2%), PICA obstruction of the FoM (17.2%), and dural scarring (87.8%). Tonsillar gliosis and intertonsillar adhesions obstructing the FoM were more common in children than adults. Tonsillar gliosis and arachnoid webs were more common among syringomyelia patients. After multivariable adjustment, none of the observed findings were independently associated with syringomyelia, preoperative symptoms, or postoperative improvement. The vast majority of patients improved postoperatively. The complication rate was low: 1.2% of patients required revision PFDD at > 3 years postoperatively, 3.6% experienced other operative complications, and 0% had CSF leaks.

CONCLUSIONS

The diversity of intradural findings and observations revealed in this study suggests that obstructive and compressive structural anomalies may be more common than previously reported among CM-I patients, both those patients with and those without syringomyelia and especially those with obstructive and compressive PICA branches. Although the authors cannot conclude that all these findings are necessarily pathological, further study may determine how they contribute to CM-I pathology and symptomatology in the setting of a compromised cisterna magna.

Long-Term Motor versus Sensory Lumbar Plexopathy After Lateral Lumbar Interbody Fusion: Single-Center Experience, Intraoperative Neuromonitoring Results, and Multivariate Analysis of Patient-Level Predictors

BACKGROUND

Although lateral lumbar interbody fusion (LLIF) is an effective surgical option for lumbar arthrodesis, postoperative plexopathies are a common complication. We characterized post-LLIF plexopathies in a large cohort and analyzed potential risk factors for each.

METHODS

A single-institutional cohort who underwent LLIF between May 2015 and December 2019 was retrospectively reviewed for postoperative lumbar plexopathies. Plexopathies were divided based on sensory and motor symptoms and duration, as well as by laterality relative to the surgical approach. We assessed these subgroups for associations with patient and surgical characteristics as well as psoas dimensions. We then evaluated risk of developing plexopathies after intraoperative neuromonitoring observations.

RESULTS

A total of 127 patients were included. The overall rate of LLIF-induced sensory or motor lumbar plexopathy was 37.8% (48/127). Of all cases, 42 were ipsilateral to the surgical approach (33.1%); conversely, 6 patients developed contralateral plexopathies (4.7%). Most (31/48; 64.6%) resolved with a follow-up interval of 402 days in the plexopathy group. Of ipsilateral cases, 24 patients experienced persistent (>90 days) postoperative sensory symptoms (18.9%), whereas 20 experienced persistent weakness (15.7%). More levels fused predicted persistent sensory symptoms (odds ratio, 1.714 [1.246-2.359]; P = 0.0085), whereas surgical duration predicted persistent weakness (odds ratio, 1.004 [1.002-1.006]; P = 0.0382). Psoas anatomic variables were not significantly associated with plexopathy. Nonresolution of intraoperative evoked motor potential alerts was a significant risk factor for developing plexopathies (relative risk, 2.29 [1.17-4.45]).

CONCLUSIONS

Post-LLIF plexopathies are common but usually resolve. Surgical complexity and unresolved neuromonitoring alerts are possible risk factors for persistent plexopathy.

Right Ventricular Architectural Remodeling and Functional Adaptation in Pulmonary Hypertension

BACKGROUND

Global indices of right ventricle (RV) function provide limited insights into mechanisms underlying RV remodeling in pulmonary hypertension (PH). While RV myocardial architectural remodeling has been observed in PH, its effect on RV adaptation is poorly understood.

METHODS

Hemodynamic assessments were performed in 2 rodent models of PH. RV free wall myoarchitecture was quantified using generalized Q-space imaging and tractography analyses. Computational models were developed to predict RV wall strains. Data from animal studies were analyzed to determine the correlations between hemodynamic measurements, RV strains, and structural measures.

RESULTS

In contrast to the PH rats with severe RV maladaptation, PH rats with mild RV maladaptation showed a decrease in helical range of fiber orientation in the RV free wall (139º versus 97º; P=0.029), preserved global circumferential strain, and exhibited less reduction in right ventricular-pulmonary arterial coupling (0.029 versus 0.017 mm/mm Hg; P=0.037). Helical range correlated positively with coupling (P=0.036) and stroke volume index (P<0.01). Coupling correlated with global circumferential strain (P<0.01) and global radial strain (P<0.01) but not global longitudinal strain.

CONCLUSIONS

Data analysis suggests that adaptive RV architectural remodeling could improve RV function in PH. Our findings suggest the need to assess RV architecture within routine screenings of PH patients to improve our understanding of its prognostic and therapeutic significance in PH.

Compromised Cranio-Spinal Suspension in Chiari Malformation Type 1: A Potential Role as Secondary Pathophysiology

In Chiari Malformation Type I (CM1), low-lying tonsils obstruct the cisterna magna at the foramen magnum, thereby compromising the essential juncture between the cranial and spinal compartments. The anatomical obstruction of the cisterna magna inhibits bi-directional CSF flow as well as CSF pulse pressure equilibration between the intracranial compartment and the intraspinal compartment in response to instances of increased intracranial pressure. Less understood, however, are the roles of the spinal cord suspension structures at the craniocervical junction which lend viscoelastic support to the spinal cord and tonsils, as well as maintain the anatomical integrity of the cisterna magna and the dura. These include extradural ligaments including the myodural bridges (MDBs), as well as intradural dentate ligaments and the arachnoid framework. We propose that when these elements are disrupted by the cisterna magna obstruction, tonsillar pathology, and altered CSF dynamics, there may arise a secondary pathophysiology of compromised and dysfunctional cranio-spinal suspension in CM1. We present intraoperative images and videos captured during surgical exposure of the craniocervical junction in CM1 to illustrate this proposal.

Influence of socioeconomic factors on discharge disposition following traumatic cervicothoracic spinal cord injury at level I and II trauma centers in the United States

BACKGROUND

Discharge to acute rehabilitation is strongly correlated with functional recovery after traumatic injury, including spinal cord injury (SCI). However, services such as acute care rehabilitation and Skilled Nursing Facilities (SNF) are expensive. Our objective was to understand if high-cost, resource-intensive post-discharge rehabilitation or alternative care facilities are utilized at disparate rates across socioeconomic groups after SCI.

METHODS

We performed a cohort analysis using the National Trauma Data Bank® tabulated from 2012-2016. Eligible patients had a diagnosis of cervical or thoracic spine fracture with spinal cord injury (SCI) and were treated surgically. We evaluated associations of sociodemographic and psychosocial variables with non-home discharge (e.g., discharge to SNF, other healthcare facility, or intermediate care facility) via multivariable logistic regression while correcting for injury severity and hospital characteristics.

RESULTS

We identified 3933 eligible patients. Patients who were older, male (OR=1.29 95% Confidence Interval [1.07-1.56], p=.007), insured by Medicare (OR=1.45 [1.08-1.96], p=.015), diagnosed with a major psychiatric disorder (OR=1.40 [1.03-1.90], p=.034), had a higher Injury Severity Score (OR=5.21 [2.96-9.18], p<.001) or a lower Glasgow Coma Score (3-8 points, OR=2.78 [1.81-4.27], p<.001) had a higher chance of a non-home discharge. The only sociodemographic variable associated with lower likelihood of utilizing additional healthcare facilities following discharge was uninsured status (OR=0.47 [0.37-0.60], p<.001).

CONCLUSIONS

Uninsured patients are less likely to be discharged to acute rehabilitation or alternative healthcare facilities following surgical management of SCI. High out-of-pocket costs for uninsured patients in the United States may deter utilization of these services.

Influence of Sociodemographic and Psychosocial Factors on Length of Stay After Surgical Management of Traumatic Spine Fracture with Spinal Cord Injury

OBJECTIVE

Identifying patients at risk of increased health care resource utilization is a valuable opportunity to develop targeted preoperative and perioperative interventions. In the present investigation, we sought to examine patient sociodemographic factors that predict prolonged length of stay (LOS) after traumatic spine fracture.

METHODS

We performed a cohort analysis using the National Trauma Data Bank tabulated during 2012-2016. Eligible patients were those who were diagnosed with cervical or thoracic spine fracture with spinal cord injury and who were treated surgically. We evaluated the effects of sociodemographic as well as psychosocial variables on LOS by negative binomial regression and adjusted for injury severity, injury mechanism, and hospital characteristics.

RESULTS

We identified 3856 eligible patients with a median LOS of 9 days (interquartile range, 6-15 days). Patients in older age categories, who were male (incidence rate ratio (IRR), 1.05; 95% confidence interval [CI], 1.01-1.09), black (IRR, 1.12; CI, 1.05-1.19) or Hispanic (IRR, 1.09; CI, 1.03-1.16), insured by Medicaid (IRR, 1.24; CI, 1.17-1.31), or had a diagnosis of alcohol use disorder (IRR, 1.12; CI, 1.06-1.18) were significantly more likely to have a longer LOS. In addition, patients with severe injury on Injury Severity Score (IRR, 1.32; CI, 1.14-1.53) and lower Glasgow Coma Scale (GCS) scores (GCS score 3-8, IRR, 1.44; CI, 1.35-1.55; GCS score 9-11, IRR, 1.40; CI, 1.25-1.58) on admission had a significantly lengthier LOS. Patients admitted to a hospital in the Southern United States (IRR, 1.09; CI, 1.05-1.14) had longer LOS.

CONCLUSIONS

Socioeconomic factors such as race, insurance status, and alcohol use disorder were associated with a prolonged LOS after surgical management of traumatic spine fracture with spinal cord injury.

Not Just an Anchor: The Human Filum Terminale Contains Stretch Sensitive and Nociceptive Nerve Endings and Responds to Electrical Stimulation With Paraspinal Muscle Activation

BACKGROUND

Neural components of the fibrous filum terminale (FT) are well known but are considered as embryonic remnants without functionality.

OBJECTIVE

To investigate the ultrastructure of human FT specimens for sensory nerve endings and record paraspinal muscle activity on electrostimulation of the FT.

METHODS

We prospectively investigated a cohort of 53 patients who underwent excision of the FT for the treatment of tethered cord syndrome. Surgical FT specimens were investigated by light and transmission electron microscopy. Intraoperative electrophysiological routine monitoring was extended by recording paraspinal muscles above and below the laminotomy level.

RESULTS

Light microscopy revealed tiny peripheral nerves piercing the pia mater of the FT and entering its fibrous core. Transmission electron microscopy unveiled within the fibrous core of the FT myelinated nerve structures in 8 of the 53 patients and unmyelinated ones in 10 of the 53 patients. Both nerve endings encapsulated in fibrous tissue or unencapsulated nonmyelinated Schwann cell nerve bundles, that is, Remak cells, were found. Those nerve endings resembled mechanoreceptor and nociceptive receptor structures found in human skin, muscle tendons, and skeletal ligaments. Specifically, we found Ruffini mechanoreceptors and in addition nerve endings which resembled nociceptive glioneural structures of the skin. Bipolar electrostimulation of the FT was associated with paraspinal muscle activity above and below the spinal segment at which the FT was stimulated.

CONCLUSION

Morphological and electrophysiological results indicate the presence of functional sensory nerve endings in the FT. Like other spine ligaments, the FT may serve as a proprioceptive element but may also contribute to back pain in spine disorders.

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.

Pedicle Screw Placement Using Intraoperative Computed Tomography and Computer-Aided Spinal Navigation Improves Screw Accuracy and Avoids Postoperative Revisions: Single-Center Analysis of 1400 Pedicle Screws

OBJECTIVE

Intraoperative computed tomography and navigation (iCT-Nav) is increasingly used to aid spinal instrumentation. We aimed to document the accuracy and revision rate of pedicle screw placement across many screws placed using iCT-Nav. We also assess patient-level factors predictive of high-grade pedicle breach.

METHODS

Medical records of patients who underwent iCT-Nav pedicle screw placement between 2015 and 2017 at a single center were retrospectively reviewed. Screw placement accuracy was individually assessed for each screw using the 2-mm incremental grading system for pedicle breach. Predictors of high-grade (>2 mm) breach were identified using multiple logistic regression.

RESULTS

In total, 1400 pedicle screws were placed in 208 patients undergoing cervicothoracic (29; 13.9%), thoracic (30; 14.4), thoracolumbar (19; 9.1%) and lumbar (130; 62.5%) surgeries. iCT-Nav afforded high-accuracy screw placement, with 1356 of 1400 screws (96.9%) being placed accurately. In total, 37 pedicle screws (2.64%) were revised intraoperatively during the index surgery across 31 patients, with no subsequent returns to the operating room because of screw malpositioning. After correcting for potential confounders, males were less likely to have a high-grade breach (odds ratio [OR] 0.21; 95% confidence interval [CI] 0.10-0.59, P = 0.003) whereas lateral (OR 6.21; 95% CI 2.47-15.52, P < 0.001) or anterior (OR 5.79; 95% CI2.11-15.88, P = 0.001) breach location were predictive of a high-grade breach.

CONCLUSIONS

iCT-Nav with postinstrumentation intraoperative imaging is associated with a reduced need for costly postoperative return to the operating room for screw revision. In comparison with studies of navigation without iCT where 1.5%-1.7% of patients returned for a second surgery, we report 0 revision surgeries due to screw malpositioning.

Two dimensional computational model coupling myoarchitecture-based lingual tissue mechanics with liquid bolus flow during oropharyngeal swallowing

Biomechanical relationships involving lingual myoanatomy, contractility, and bolus movement are fundamental properties of human swallowing. To portray the relationship between lingual deformation and bolus flow during swallowing, a weakly one-way solid-fluid finite element model (FEM) was derived employing an elemental mesh aligned to magnetic resonance diffusional tractography (Q-space MRI, QSI) of the human tongue, an arbitrary Lagrangian-Eulerian (ALE) formulation with remeshing to account for the effects of lingual surface (boundary) deformation, an implementation of patterned fiber shortening, and a computational visualization of liquid bolus flow. Representing lingual tissue deformation in terms of its 2D principal Lagrangian strain in the mid-sagittal plane, we demonstrated that the swallow sequence was characterized by initial superior-anterior expansion directed towards the hard palate, followed by sequential, radially directed, contractions of the genioglossus and verticalis to promote lingual rotation (lateral perspective) and propulsive displacement. We specifically assessed local bolus velocity as a function of viscosity (perfect slip conditions) and observed that a low viscosity bolus (5 cP) exhibited maximal displacement, surface spreading and local velocity compared to medium (110 cP, 300 cP) and high (525 cP) viscosity boluses. Analysis of local nodal velocity revealed that all bolus viscosities exhibited a bi-phasic progression, with the low viscosity bolus being the most heterogeneous and fragmented and the high viscosity bolus being the most homogenous and cohesive. Intraoral bolus cohesion was depicted in terms of the distributed velocity gradient, with higher gradients being associated with increased shear rate and bolus fragmentation. Lastly, we made a sensitivity analysis on tongue stiffness and contractility by varying the degree of extracellular matrix (ECM) stiffness through effects on the Mooney-Rivlin derived passive matrix and by varying maximum tetanized isometric stress, and observed that a graded increase of ECM stiffness was associated with reduced bolus spreading, posterior displacement, and surface velocity gradients, whereas a reduction of global contractility resulted in a graded reduction of obtainable accommodation volume, absent bolus spreading, and loss of posterior displacement. We portray a unidirectionally coupled solid-liquid FEM which associates myoarchitecture-based lingual deformation with intra-oral bolus flow, and deduce that local elevation of the velocity gradient correlates with bolus fragmentation, a precondition believed to be associated with aspiration vulnerability during oropharyngeal swallowing.

Influence of psychosocial and sociodemographic factors in the surgical management of traumatic cervicothoracic spinal cord injury at level I and II trauma centers in the United States

Background

Socioeconomic factors can bias clinician decision-making in many areas of medicine. Psychosocial characteristics such as diagnosis of alcoholism, substance abuse, and major psychiatric disorder are emerging as potential sources of conscious and unconscious bias. We hypothesized that these psychosocial factors, in addition to socioeconomic factors, may impact the decision to operate on patients with a traumatic cervicothoracic fracture and associated spinal cord injury (SCI).

Methods

We performed a cohort analysis using clinical data from 2012-2016 in the American College of Surgeons (ACS) National Trauma Data Bank at academic level I and II trauma centers. Patients were eligible if they had a diagnosis of cervicothoracic fracture with SCI. Using ICD codes, we evaluated baseline characteristics including race; insurance status; diagnosis of alcoholism, substance abuse, or major psychiatric disorder; admission drug screen and blood alcohol level; injury characteristics and severity; and hospital characteristics including geographic region, non-profit status, university affiliation, and trauma level. Factors significantly associated with surgical intervention in univariate analysis were eligible for inclusion in multivariate logistic regression.

Results

We identified 6,655 eligible patients, of whom 62% underwent surgical treatment (n=4,137). Patients treated non-operatively were more likely to be older; be female; be Black or Hispanic; have Medicare, Medicaid, or no insurance; have been assaulted; have been injured by a firearm; have thoracic fracture; have less severe injuries; have severe TBI; be treated at non-profit hospitals; and be in the Northeast or Western U.S. (all P<0.01). After adjusting for confounders in multivariate analysis, only insurance status remained associated with operative treatment. Medicaid patients (OR=0.81; P=0.021) and uninsured patients (OR=0.63; P<0.001) had lower odds of surgery relative to patients with private insurance. Injury severity and facility characteristics also remained significantly associated with surgical management following multivariate regression.

Conclusions

Psychosocial characteristics such as diagnosis of alcoholism, substance abuse, or psychiatric illness do not appear to bias the decision to operate after traumatic cervicothoracic fracture with SCI. Baseline sociodemographic imbalances were explained largely by insurance status, injury, and facility characteristics in multivariate analysis.

Transition from Compounded to Monotherapy Intrathecal Pain Medication Reduces Drug Costs: Retrospective Analysis of Patient Billing Data

BACKGROUND

Chronic pain accounts for several hundred billion dollars in total treatment costs, and lost productivity annually. Selecting cost-effective pain treatments can reduce the financial burden on both individuals and society. Targeted drug delivery (TDD), whereby medications used to treat pain are delivered directly to the intrathecal space, remains an important treatment modality for chronic pain refractory to oral medication management. These medications can be administered alone (monotherapy), or in conjunction with other medications to give a synergistic affect (compounded therapy). While compounded therapy is often prescribed for pain refractory to both oral management and intrathecal monotherapy, compounded administration has not been approved by the United States Food and Drug Administration (FDA), and is thought to be more expensive. In this study, we hypothesized that TDD delivering monotherapy vs compounded therapy would differ significantly in cost.

OBJECTIVES

In 2015, a pharmacy-led initiative resulted in an institution-wide policy requiring that all TDD patients, being treated with compounded therapy, be transitioned to FDA-approved intrathecal monotherapy. The intent of this new policy was to eliminate use of non-FDA approved, "off-label" medications. During this transition, our practice used the opportunity to retrospectively analyze and compare the costs of monotherapy vs compounded therapy.

STUDY DESIGN

Billing, drug dosing, and pain data were collected from 01/2015 to 01/2019, and reviewed retrospectively for patients originally on compounded intrathecal medication therapy, and compared before and after transition to monotherapy.

SETTING

A multidisciplinary hospital-based spine center within an academic tertiary care facility.

METHODS

Electronic medical records from the institutional TDD program were retrospectively reviewed to identify all patients on compounded drug therapy before the transition period (2015-2016). Patients were excluded from the study if they chose to switch their care to another practice rather than transitioning from compounded therapy to monotherapy. Cost per medications refill, cost per year, and reported pain scale before and after the transition were computed, and differences were compared using unpaired t tests. Refill costs of individual drugs were also compared.

RESULTS

Of 46 patients originally on compounded therapy, 26 patients met inclusion criteria. The most common pre-transition drugs administered as compounded therapy were bupivacaine (n = 17), morphine (n = 15), and clonidine (n = 14), while hydromorphone (n = 10), baclofen (n = 5), and fentanyl (n = 1) were less common. There was a 51.3% decrease in cost per refill (P = 0.135) and a 50.0% decrease in cost per year (P = 0.283) after transition. Morphine and clonidine were both significantly more expensive than hydromorphone and bupivacaine (P < 0.05). After removing cases in which hydromorphone was the baseline opiate, there was a 64.8% decrease in cost per refill (P = 0.041) and a 66.8% decrease in cost per year (P = 0.190). There was no significant difference in the average reported pain scale across the transition (P = 0.323), suggesting stable pain management efficacy.

LIMITATIONS

This retrospective study is limited by its small cohort size and lack of a control group.

CONCLUSIONS

Based on single-institutional billing data, transition from compounded therapy to monotherapy TDD resulted in cost savings, dependent on the specific combination of drugs initially used for therapy. A larger multi-institutional study is indicated.

Two-trajectory laser amygdalohippocampotomy: Anatomic modeling and initial seizure outcomes

OBJECTIVE

Laser interstitial thermal therapy (LITT) for mesial temporal lobe epilepsy (mTLE) is typically performed with one trajectory to target the medial temporal lobe (MTL). MTL structures such as piriform and entorhinal cortex are epileptogenic, but due to their relative geometry, they are difficult to target with one trajectory while simultaneously maintaining adequate ablation of the amygdala and hippocampus. We hypothesized that a two-trajectory approach could improve ablation of all relevant MTL structures. First, we created large-scale computer simulations to compare idealized one- vs two-trajectory approaches. A two-trajectory approach was then validated in an initial cohort of patients.

METHODS

We used magnetic resonance imaging (MRI) from the Human Connectome Project (HCP) to create subject-specific target structures consisting of hippocampus, amygdala, and piriform/entorhinal/perirhinal cortex. An algorithm searched for safe potential trajectories along the hippocampal axis (catheter one) and along the amygdala-piriform axis (catheter two) and compared this to a single trajectory optimized over all structures. The proportion of each structure ablated at various burn radii was evaluated. A cohort of 11 consecutive patients with mTLE received two-trajectory LITT; demographic, operative, and outcome data were collected.

RESULTS

The two-trajectory approach was superior to the one-trajectory approach at nearly all burn radii for all hippocampal subfields and amygdala nuclei (p < .05). Two-laser trajectories achieved full ablation of MTL cortical structures at physiologically realistic burn radii, whereas one-laser trajectories could not. Five patients with at least 1 year of follow-up (mean = 21.8 months) experienced Engel class I outcomes; 6 patients with less than 1 year of follow-up (mean = 6.6 months) are on track for Engel class I outcomes.

SIGNIFICANCE

Our anatomic analyses and initial clinical results suggest that LITT amygdalohippocampotomy performed via two-laser trajectories may promote excellent seizure outcomes. Future studies are required to validate the long-term clinical efficacy and safety of this approach.

Supplementation of Screw-Rod C1-C2 Fixation With Posterior Arch Femoral Head Allograft Strut

BACKGROUND

Numerous C1-C2 fixation techniques exist for the treatment of atlantoaxial instability. Limitations of screw-rod and sublaminar wiring techniques include C2 nerve root sacrifice and dural injury, respectively. We present a novel technique that utilizes a femoral head allograft cut with a keyhole that rests posteriorly on the arches of C1 and C2 and straddles the C2 spinous process, secured by sutures.

OBJECTIVE

To offer increased fusion across C1-C2 without the passage of sublaminar wiring or interarticular arthrodesis.

METHODS

A total of 6 patients with atlantoaxial instability underwent C1-C2 fixation using our method from 2015 to 2016. After placement of a C1-C2 screw/rod construct, a cadaveric frozen femoral head allograft was cut into a half-dome with a keyhole and placed over the already decorticated dorsal C1 arch and C2 spinous process. Notches were created in the graft and sutures were placed in the notches and around the rods to secure it firmly in place.

RESULTS

The femoral head's shape allowed for creation of a graft that provides excellent surface area for fusion across C1-C2. There were no intraoperative complications, including dural tears. Postoperatively, no patients had sensorimotor deficits, pain, or occipital neuralgia. 5 patients demonstrated clinical resolution of symptoms by 3 mo and radiographic (computed tomography) evidence of fusion at 1 yr. One patient had good follow-up at 1 mo but died due to complications of Alzheimer disease.

CONCLUSION

The posterior arch femoral head allograft strut technique with securing sutures is a viable option for supplementing screw-rod fixation in the treatment of complex atlantoaxial instability.

Existing clinical evidence on the use of cellular bone matrix grafts in spinal fusion: updated systematic review of the literature

OBJECTIVE

Spinal fusion surgery is increasingly common; however, pseudarthrosis remains a common complication affecting as much as 15% of some patient populations. Currently, no clear consensus on the best bone graft materials to use exists. Recent advances have led to the development of cell-infused cellular bone matrices (CBMs), which contain living components such as mesenchymal stem cells (MSCs). Relatively few clinical outcome studies on the use of these grafts exist, although the number of such studies has increased in the last 5 years. In this study, the authors aimed to summarize and critically evaluate the existing clinical evidence on commercially available CBMs in spinal fusion and reported clinical outcomes.

METHODS

The authors performed a systematic search of the MEDLINE and PubMed electronic databases for peer-reviewed, English-language original articles (1970-2020) in which the articles' authors studied the clinical outcomes of CBMs in spinal fusion. The US National Library of Medicine electronic clinical trials database (www.ClinicalTrials.gov) was also searched for relevant ongoing clinical trials.

RESULTS

Twelve published studies of 6 different CBM products met inclusion criteria: 5 studies of Osteocel Plus/Osteocel (n = 354 unique patients), 3 of Trinity Evolution (n = 114), 2 of ViviGen (n = 171), 1 of map3 (n = 41), and 1 of VIA Graft (n = 75). All studies reported high radiographic fusion success rates (range 87%-100%) using these CBMs. However, this literature was overwhelmingly limited to single-center, noncomparative studies. Seven studies disclosed industry funding or conflicts of interest (COIs). There are 4 known trials of ViviGen (3 trials) and Bio4 (1 trial) that are ongoing.

CONCLUSIONS

CBMs are a promising technology with the potential of improving outcome after spinal fusion. However, while the number of studies conducted in humans has tripled since 2014, there is still insufficient evidence in the literature to recommend for or against CBMs relative to cheaper alternative materials. Comparative, multicenter trials and outcome registries free from industry COIs are indicated.

Reappraisal of Pediatric Normal-Pressure Hydrocephalus

While normal-pressure hydrocephalus (NPH) is most commonly diagnosed in older adulthood, a significant body of literature has accumulated over half a century documenting the clinical phenomenon of an NPH-like syndrome in pediatric patients. As in adult NPH, it is likely that pediatric NPH occurs due to a heterogeneous array of developmental, structural, and neurodegenerative pathologies, ultimately resulting in aberrant cerebrospinal fluid (CSF) flow and distribution within and around the brain. In this review, we aimed to systematically survey the existing clinical evidence supporting the existence of a pediatric form of NPH, dating back to the original recognition of NPH as a clinically significant subtype of communicating hydrocephalus. Leveraging emergent trends from the old and more recent published literature, we then present a modern characterization of pediatric NPH as a disorder firmly within the same disease spectrum as adult NPH, likely with overlapping etiology and pathophysiological mechanisms. Exemplary cases consistent with the diagnosis of pediatric NPH selected from the senior author’s neurosurgical practice are then presented alongside the systematic review to aid in discussion of the typical clinical and radiographic manifestations of pediatric NPH. Common co-morbidities and modern surgical treatment options are also described.

A transpedicular approach to complex ventrally situated thoracic intradural extramedullary tumors: technique, indications, and multiinstitutional case series

OBJECTIVE

Ventrally situated thoracic intradural extramedullary tumors are surgically challenging and difficult to access, and they may be complicated by extensive adhesions and calcifications. Selecting an approach for adequate ventral access is key to complete resection and optimization of outcomes. The authors present a case series of patients who underwent resection of ventral thoracic intradural extramedullary tumors and discuss indications and considerations for this technique. Additionally, they describe the use of a posterolateral transpedicular approach for resection of ventral thoracic intradural extramedullary tumors compared with other techniques, and they summarize the literature supporting its application.

METHODS

From May 2017 to August 2020, 5 patients with ventral thoracic intradural extramedullary tumors underwent resection at one of the two academic institutions.

RESULTS

Patient ages ranged from 47 to 75 (mean 63.4) years. All tumors were diagnosed as meningiomas or schwannomas by histological examination. Three of the 5 patients had evidence of partial or extensive tumor calcification. Four of the 5 patients underwent an initial posterolateral transpedicular approach for resection, with positive radiographic and clinical outcomes from surgery. One patient initially underwent an unsuccessful traditional direct posterior approach and required additional resection 2 years later after interval disease progression. There were no postoperative wound infections, CSF leaks, or other complications related to the transpedicular approach.

CONCLUSIONS

Posterolateral transpedicular tumor resection is a safe technique for the treatment of complex ventrally situated thoracic intradural extramedullary tumors compared with the direct posterior approach. Anecdotally, this approach appears to be particularly beneficial in patients with calcified tumors.

Demand for Essential Nonambulatory Neurosurgical Care Decreased While Acuity of Care Increased During the Coronavirus Disease 2019 (COVID-19) Surge

Background

In times of health resource reallocation, capacities must remain able to meet a continued demand for essential, nonambulatory neurosurgical acute care. This study sought to characterize the demand for and provision of neurosurgical acute care during the coronavirus disease 2019 (COVID-19) pandemic.

Methods

This single-center cross-sectional observational analysis compared nonambulatory neurosurgical consult encounters during the peri-surge period (March 9 to May 31, 2020) with those during an analogous period in 2019. Outcomes included consult volume, distribution of problem types, disease severity, and rate of acute operative intervention.

Results

A total of 1494 neurosurgical consults were analyzed. Amidst the pandemic surge, 583 consults were seen, which was 6.4 standard deviations below the mean among analogous 2016–2019 periods (mean 873; standard deviation 45, P = 0.001). Between 2019 and 2020, the proportion of degenerative spine consults decreased in favor of spinal trauma (25.6% vs. 34% and 51.9% vs. 41.4%, P = 0.088). Among aneurysmal subarachnoid hemorrhage cases, poor-grade (Hunt and Hess grades 4–5) presentations were more common (30% vs. 14.8%, P = 0.086). A greater proportion of pandemic era consults resulted in acute operative management, with an unchanged absolute frequency of acutely operative consults (123/583 [21.1%] vs. 120/911 [13.2%], P < 0.001).

Conclusions

Neurosurgical consult volume during the pandemic surge hit a 5-year institutional low. Amidst vast reallocation of health care resources, demand for high-acuity nonambulatory neurosurgical care continued and proportionally increased for greater-acuity pathologies. In our continued current pandemic as well as any future situations of mass health resource reallocation, neurosurgical acute care capacities must be preserved.

Outcomes of infratentorial cranial surgery for tumor resection in older patients: An analysis of the National Surgical Quality Improvement Program

Background:

Poorer outcomes for infratentorial tumor resection have been reported. There is a lack of large multicenter analyses describing infratentorial surgery outcomes in older patients. We characterized outcomes in patients aged ≥65 years undergoing infratentorial cranial surgery.

Methods:

The National Surgical Quality Improvement Project database was queried from 2012 to 2018 for patients ≥18 years undergoing elective infratentorial cranial surgery for tumor resection. Patients were grouped into 65–74 years, ≥75 years, and 18–64 years cohorts. Multivariable regressions compared outcome measures.

Results:

Of 2212 patients, 28.3% were ≥65 years, of whom 24.8% were ≥75 years. Both older subpopulations had worse American Society of Anesthesiologists classification compared to controls (P < 0.01) and more comorbidities. Patients 65–74 and ≥75 years had higher rates of major complication (adjusted odds ratio [aOR] = 1.77, 95% CI = 1.13–2.79 and aOR = 3.44, 95% CI = 1.96–6.02, respectively), prolonged length of stay (LOS) (aOR = 1.89, 95% CI = 1.15–3.12 and aOR = 3.00, 95% CI = 1.65–5.44, respectively), and were more likely to be discharged to a location other than home (aOR = 2.43, 95% CI =1.73–3.4 and aOR = 3.41, 95% CI = 2.18–5.33, respectively) relative to controls. Patients ≥75 had higher rates of readmission (aOR = 1.86, 95% CI = 1.13–3.08) and mortality (aOR = 3.28, 95% CI = 1.21–8.89) at 30 days.

Conclusion:

Patients ≥65 years experienced more complications, prolonged LOS, and were less often discharged home than adults <65 years. Patients ≥75 years had higher rates of 30-day readmission and mortality. There is a need for careful preoperative optimization in older patients undergoing infratentorial tumor cranial surgery.

Amino terminus of cardiac myosin binding protein-C regulates cardiac contractility

Phosphorylation of cardiac myosin binding protein-C (cMyBP-C) regulates cardiac contraction through modulation of actomyosin interactions mediated by the protein's amino terminal (N')-region (C0-C2 domains, 358 amino acids). On the other hand, dephosphorylation of cMyBP-C during myocardial injury results in cleavage of the 271 amino acid C0-C1f region and subsequent contractile dysfunction. Yet, our current understanding of amino terminus region of cMyBP-C in the context of regulating thin and thick filament interactions is limited. A novel cardiac-specific transgenic mouse model expressing cMyBP-C, but lacking its C0-C1f region (cMyBP-C^∆C0-C1f), displayed dilated cardiomyopathy, underscoring the importance of the N'-region in cMyBP-C. Further exploring the molecular basis for this cardiomyopathy, in vitro studies revealed increased interfilament lattice spacing and rate of tension redevelopment, as well as faster actin-filament sliding velocity within the C-zone of the transgenic sarcomere. Moreover, phosphorylation of the unablated phosphoregulatory sites was increased, likely contributing to normal sarcomere morphology and myoarchitecture. These results led us to hypothesize that restoration of the N'-region of cMyBP-C would return actomyosin interaction to its steady state. Accordingly, we administered recombinant C0-C2 (rC0-C2) to permeabilized cardiomyocytes from transgenic, cMyBP-C null, and human heart failure biopsies, and we found that normal regulation of actomyosin interaction and contractility was restored. Overall, these data provide a unique picture of selective perturbations of the cardiac sarcomere that either lead to injury or adaptation to injury in the myocardium.

A minimally invasive lateral approach with CT navigation for open biopsy and diagnosis of Nocardia nova L4–5 discitis osteomyelitis: illustrative case

BACKGROUND

Lumbar spine osteomyelitis can be refractory to conventional techniques for identifying a causal organism. In cases in which a protracted antibiotic regimen is indicated, obtaining a conclusive yield on biopsy is particularly important. Although lateral transpsoas approaches and intraoperative computed tomography (CT) navigation are well documented as techniques used for spinal arthrodesis, their utility in vertebral biopsy has yet to be reported in any capacity.

OBSERVATIONS

In a 44-year-old male patient with a history of Nocardia bacteremia, CT-guided biopsy failed to confirm the microbiology of an L4–5 discitis osteomyelitis. The patient underwent a minimally invasive open biopsy in which a lateral approach with intraoperative guidance was used to access the infected disc space retroperitoneally. A thin film was obtained and cultured Nocardia nova, and the patient was treated accordingly with a long course of trimethoprim-sulfamethoxazole.

LESSONS

The combination of a lateral transpsoas approach with intraoperative navigation is a valuable technique for obtaining positive yield in cases of discitis osteomyelitis of the lumbar spine refractory to CT-guided biopsy.

Computer-Assisted Measurement of Traumatic Brain Hemorrhage Volume Is More Predictive of Functional Outcome and Mortality than Standard ABC/2 Method: An Analysis of Computed Tomography Imaging Data from the Progesterone for Traumatic Brain Injury Experimental Clinical Treatment Phase-III Trial

Hemorrhage volume is an important variable in emergently assessing traumatic brain injury (TBI). The most widely used method for rapid volume estimation is ABC/2, a simple algorithm that approximates lesion geometry as perfectly ellipsoid. The relative prognostic value of volume measurement based on more precise hematoma topology remains unknown. In this study, we compare volume measurements obtained using ABC/2 versus computer-assisted volumetry (CAV) for both intra- and extra-axial traumatic hemorrhages, and then quantify the association of measurements using both methods with patient outcome following moderate to severe TBI. A total of 517 computer tomography (CT) scans acquired during the Progesterone for Traumatic Brain Injury Experimental Clinical Treatment Phase-III (ProTECTIII) multi-center trial were retrospectively reviewed. Lesion volumes were measured using ABC/2 and CAV. Agreement between methods was tested using Bland-Altman analysis. Relationship of volume measurements with 6-month mortality, Extended Glasgow Outcome Scale (GOS-E), and Disability Rating Scale (DRS) were assessed using linear regression and area under the curve (AUC) analysis. In subdural hematoma (SDH) >50cm3, ABC/2 and CAV produce significantly different volume measurements (p < 0.0001), although the difference was not significant for smaller SDH or intra-axial lesions. The disparity between ABC/2 and CAV measurements varied significantly with hematoma size for both intra- and extra-axial lesions (p < 0.0001). Across all lesions, volume was significantly associated with outcome using either method (p < 0.001), but CAV measurement was a significantly better predictor of outcome than ABC/2 estimation for SDH. Among large traumatic SDH, ABC/2 significantly overestimates lesion volume compared with measurement based on precise bleed topology. CAV also offers significantly better prediction of patient functional outcofme and mortality.

Decreasing External Ventricular Drain Infection Rates in the Neurocritical Care Unit: 12-Year Longitudinal Experience at a Single Institution

OBJECTIVE

External ventricular drain (EVD) placement is a common neurosurgical procedure, and EVD-related infection is a significant complication. We examined the effect of infection control protocol changes on EVD-related infection incidence.

METHODS

Changes in EVD placement protocol and incidence density of infections after implementation of protocol changes in the neurocritical care unit were tracked from 2007 to 2019. EVD infections were defined using a modified U.S. Centers for Disease Control and Prevention National Healthcare Safety Network surveillance definition of meningitis/ventriculitis for patients with EVDs in situ for at least 2 days confirmed by positive culture. Contribution of protocol changes to EVD infection risk was assessed via multivariate regression.

RESULTS

Fifteen major changes in EVD protocol were associated with a reduction in infections from 6.7 to 2.0 per 1000 EVD days (95% confidence interval [CI], 4.1-5.3; P < 0.001). Gram-positive bacterial infection incidence decreased from 4.8 to 1.7 per 1000 EVD days (95% CI, 2.3-3.9; P = 0.00882) and gram-negative infection incidence decreased from 1.9 to 0.5 per 1000 EVD days (95% CI, 0.6-2.3; P = 0.0303). Of all protocol changes since 2007, the largest reduction in incidence was 3.9 infections per 1000 days (95% CI, 0.50-7.30; P = 0.011), associated with combined standardization of reduced EVD sampling frequency, cutaneous antisepsis with alcoholic chlorhexidine before EVD placement, and use of a subcutaneous tunneling technique during EVD insertion.

CONCLUSIONS

The most significant reduction in EVD infections may be achieved through the combination of reducing EVD sampling frequency and standardizing alcoholic chlorhexidine cutaneous antisepsis and subcutaneous tunneling of the EVD catheter.

A modern multidisciplinary approach to a large cervicothoracic chordoma using staged en bloc resection with intraoperative image-guided navigation and 3D-printed modeling: illustrative case

BACKGROUND

Cervicothoracic junction chordomas are uncommon primary spinal tumors optimally treated with en bloc resection. Although en bloc resection is the gold standard for treatment of mobile spinal chordoma, tumor location, size, and extent of involvement frequently complicate the achievement of negative margins. In particular, chordoma involving the thoracic region can require a challenging anterior access, and en bloc resection can lead to a highly destabilized spine.

OBSERVATIONS

Modern technological advances make en bloc resection more technically feasible than ever before. In this case, the successful en bloc resection of a particularly complex cervicothoracic junction chordoma was facilitated by a multidisciplinary surgical approach that maximized the use of intraoperative computed tomography–guided spinal navigation and patient-specific three-dimensional–printed modeling.

LESSONS

The authors review the surgical planning and specific techniques that facilitated the successful en bloc resection of this right-sided chordoma via image-guided parasagittal osteotomy across 2 stages. The integration of emerging visualization technologies into complex spinal column tumor management may help to provide optimal oncological care for patients with challenging primary tumors of the mobile spine.

Early outcomes of supratentorial cranial surgery for tumor resection in older patients

With longevity increasing in the United States, more older individuals are presenting with supratentorial brain tumors. Despite improved perioperative management, there is persistent disparity in surgical resection rates among patients aged 65 years or older. We aim to assess the effects of advanced age (≥65 years) on 30-day outcomes in patients with supratentorial tumors who underwent craniotomy for supratentorial tumor resection. Data obtained in adults who underwent supratentorial tumor resections was extracted from the prospectively-collected American College of Surgeons: National Surgical Quality Improvement Program (NSQIP; 2012-2018) database. Using multivariate regression, we compared odds of major and minor complications; prolonged length-of-stay (LOS); discharge anywhere other than home; and 30-day readmission, reoperation, and mortality rates between patients aged 18-64 years (the control cohort) and those 65-74 years or ≥75 years of age. Of the 14,234 patients who underwent craniotomy for supratentorial tumors and met inclusion criteria, 30.7% were ≥65 years of age; 71.4% of these were 65-74 years and 28.6% were ≥75 years old. Compared to the control group, both older subpopulations had more medical comorbidities. Both older subgroups had increased odds of major complications and prolonged LOS relative to the control group. Older patients had greater odds of mortality at 30 days. Advanced age, defined as ≥65 years, was significantly associated with higher odds of complications, prolonged LOS, and mortality within the 30-day post- operative period after adjusting for potential confounders. Age is one important consideration when prospectively risk-stratifying patients to minimize and mitigate suboptimal perioperative outcomes.

Two-Level Separation Surgery for Thoracic Epidural Metastatic Disease: An Operative Video Demonstration

The spinal column is one of the most common regions of cancer metastasis. Spinal metastases typically occur in the vertebral body, and due to direct posterior extension or retropulsed pathological fractures, they often present with signs and symptoms of epidural spinal cord compression. This scenario requires surgical management to relieve compression and stabilize the spine. Separation surgery establishes a corridor to the ventral epidural space via pediculectomy, which allows for circumferential decompression and creation of a tumor-free margin around the thecal sac. Separation surgery is an increasingly popular method for the management of spinal metastases, particularly due to potentially reduced morbidity versus en bloc tumor resection, and its proven effectiveness when combined with spinal radiosurgery. Thus, separation surgery should be considered in patients with high-grade metastatic ventral epidural spinal cord compression. In this video, we present the case of a 61-year-old woman with metastatic hepatocellular carcinoma found to have severe spinal cord compression due to pathological vertebral body fractures at T10-T12, and ventral epidural disease at T10 and T12. The patient received T8-L2 posterior instrumented fusion and T10 and T12 separation surgery, with intraoperative cement embolization. We demonstrate the operative steps required to complete this procedure (Video 1).

Presentation of spinal cord and column tumors

Metastatic spine disease occurs in more than 10% of all cancer patients. Advances in systemic treatment for cancer has led to improved overall survival for many types of cancer, which has increased the overall incidence of spinal metastases. The most common presenting complaint of patients with spinal metastases is pain. Pain originating from spinal metastases can be oncological, mechanical, and/or neurological in nature. Early recognition of these symptoms is helpful to guide treatment and accurately gauge patient prognosis. Unfortunately, the prevalence of degenerative back pain in the general population can complicate early clinical recognition of patients with metastatic spine disease. Therefore, back pain in any patient with a history of malignancy should prompt clinicians to perform an expedited workup for metastatic disease of the spine. Diagnostic imaging and laboratory studies are part of the initial work up. Obtaining pathology via biopsy to establish tumor histology is essential to determine the appropriate treatment.

Three-Dimensional Printed Anatomic Modeling for Surgical Planning and Real-Time Operative Guidance in Complex Primary Spinal Column Tumors: Single-Center Experience and Case Series

OBJECTIVE

Three-dimensional (3D) printing has emerged as a visualization tool for clinicians and patients. We sought to use patient-specific 3D-printed anatomic modeling for preoperative planning and live intraoperative guidance in a series of complex primary spine tumors.

METHODS

Over 9 months, patients referred to a single neurosurgical provider for complex primary spinal column tumors were included. Most recent spinal magnetic resonance and computed tomography (CT) imaging were semiautomatically segmented for relevant anatomy and models were printed using polyjet multicolor printing technology. Models were available to surgical teams before and during the operative procedure. Patients also viewed the models preoperatively during surgeon explanation of disease and surgical plan to aid in their understanding.

RESULTS

Tumor models were prepared for 9 patients, including 4 with chordomas, 2 with schwannomas, 1 with osteosarcoma, 1 with chondrosarcoma, and 1 with Ewing-like sarcoma. Mean age was 50.7 years (range, 15-82 years), including 6 males and 3 females. Mean tumor volume was 129.6 cm³ (range, 3.3-250.0 cm³). Lesions were located at cervical, thoracic, and sacral levels and were treated by various surgical approaches. Models were intraoperatively used as patient-specific anatomic references throughout 7 cases and were found to be technically useful by the surgical teams.

CONCLUSIONS

We present the largest case series of 3D-printed spine tumor models reported to date. 3D-printed models are broadly useful for operative planning and intraoperative guidance in spinal oncology surgery.