Faculty Bibliography

OBJECTIVE:Rigid multiplanar thoracolumbar adult spinal deformity (ASD) cases are challenging and many require a 3-column osteotomy (3CO), specifically asymmetrical pedicle subtraction osteotomy (APSO). The outcomes and additional risks of performing APSO for the correction of concurrent sagittal-coronal deformity have yet to be adequately studied. METHODS:The authors performed a retrospective review of all ASD patients who underwent 3CO during the period from 2006 to 2019. All cases involved either isolated sagittal deformity (patients underwent standard PSO) or concurrent sagittal-coronal deformity (coronal vertical axis [CVA] ≥ 4.0 cm; patients underwent APSO). Perioperative and 2-year follow-up outcomes were compared between patients with isolated sagittal imbalance who underwent PSO and those with concurrent sagittal-coronal imbalance who underwent APSO. RESULTS:A total of 390 patients were included: 338 who underwent PSO and 52 who underwent APSO. The mean patient age was 64.6 years, and 65.1% of patients were female. APSO patients required significantly more fusions with upper instrumented vertebrae (UIV) in the upper thoracic spine (63.5% vs 43.3%, p = 0.007). Radiographically, APSO patients had greater deformity with more severe preoperative sagittal and coronal imbalance: sagittal vertical axis (SVA) 13.0 versus 10.7 cm (p = 0.042) and CVA 6.1 versus 1.2 cm (p < 0.001). In APSO cases, significant correction and normalization were achieved (SVA 13.0-3.1 cm, CVA 6.1-2.0 cm, lumbar lordosis [LL] 26.3°-49.4°, pelvic tilt [PT] 38.0°-20.4°, and scoliosis 25.0°-10.4°, p < 0.001). The overall perioperative complication rate was 34.9%. There were no significant differences between PSO and APSO patients in rates of complications (overall 33.7% vs 42.3%, p = 0.227; neurological 5.9% vs 3.9%, p = 0.547; medical 20.7% vs 25.0%, p = 0.482; and surgical 6.5% vs 11.5%, p = 0.191, respectively). However, the APSO group required significantly longer stays in the ICU (3.1 vs 2.3 days, p = 0.047) and hospital (10.8 vs 8.3 days, p = 0.002). At the 2-year follow-up, there were no significant differences in mechanical complications, including proximal junctional kyphosis (p = 0.352), pseudarthrosis (p = 0.980), rod fracture (p = 0.852), and reoperation (p = 0.600). CONCLUSIONS:ASD patients with significant coronal imbalance often have severe concurrent sagittal deformity. APSO is a powerful and effective technique to achieve multiplanar correction without higher risk of morbidity and complications compared with PSO for sagittal imbalance. However, APSO is associated with slightly longer ICU and hospital stays.

OBJECTIVE:There is an increased recognition of disproportional lumbar lordosis (LL) and artificially high pelvic incidence (PI) as a cause for positive sagittal imbalance and spinal pelvic mismatch. For such cases, a sacral pedicle subtraction osteotomy (PSO) may be indicated, although its morbidity is not well described. In this study, the authors evaluate the specific complication risks associated with S1 PSO. METHODS:A retrospective review of all adult spinal deformity patients who underwent a 3-column osteotomy (3CO) for thoracolumbar deformity from 2006 to 2019 was performed. Demographic, clinical baseline, and radiographic parameters were recorded. The primary outcome of interest was perioperative complications (surgical, neurological, and medical). Secondary outcomes of interest included case length, blood loss, and length of stay. Multivariate analysis was used to assess the risk of S1 PSO compared with 3CO at other levels. RESULTS:A total of 405 patients underwent 3CO in the following locations: thoracic (n = 55), L1 (n = 25), L2 (n = 29), L3 (n = 141), L4 (n = 129), L5 (n = 17), and S1 (n = 9). After S1 PSO, there were significant improvements in the sagittal vertical axis (14.8 cm vs 6.7 cm, p = 0.004) and PI-LL mismatch (31.7° vs 9.6°, p = 0.025) due to decreased PI (80.3° vs 65.9°, p = 0.006). LL remained unchanged (48.7° vs 57.8°, p = 0.360). The overall complication rate was 27.4%; the surgical, neurological, and medical complication rates were 7.7%, 6.2%, and 20.0%, respectively. S1 PSO was associated with significantly higher rates of overall complications: thoracic (29.1%), L1 (32.0%), L2 (31.0%), L3 (19.9%), L4 (32.6%), L5 (11.8%), and S1 (66.7%) (p = 0.018). Similarly, an S1 PSO was associated with significantly higher rates of surgical (thoracic [9.1%], L1 [4.0%], L2 [6.9%], L3 [5.7%], L4 [10.9%], L5 [5.9%], and S1 [44.4%], p = 0.006) and neurological (thoracic [9.1%], L1 [0.0%], L2 [6.9%], L3 [2.8%], L4 [7.0%], L5 [5.9%], and S1 [44.4%], p < 0.001) complications. On multivariate analysis, S1 PSO was independently associated with higher odds of overall (OR 7.93, p = 0.013), surgical (OR 20.66, p = 0.010), and neurological (OR 14.75, p = 0.007) complications. CONCLUSIONS:S1 PSO is a powerful technique for correction of rigid sagittal imbalance due to an artificially elevated PI in patients with rigid high-grade spondylolisthesis and chronic sacral fractures. However, the technique and intraoperative corrective maneuvers are challenging and associated with high surgical and neurological complications. Additional investigations into the learning curve associated with S1 PSO and complication prevention are needed.

OBJECTIVE:The correction of severe cervicothoracic sagittal deformities can be very challenging and can be associated with significant morbidity. Often, soft-tissue releases and osteotomies are warranted to achieve the desired correction. There is a paucity of studies that examine the difference in morbidity and complication profiles for Smith-Petersen osteotomy (SPO) versus 3-column osteotomy (3CO) for cervical deformity correction. METHODS:A retrospective comparison of complication profiles between posterior-based SPO (Ames grade 2 SPO) and 3CO (Ames grade 5 opening wedge osteotomy and Ames grade 6 closing wedge osteotomy) was performed by examining a single-surgeon experience from 2011 to 2018. Patients of interest were individuals who had a cervical sagittal vertical axis (cSVA) > 4 cm and/or cervical kyphosis > 20° and who underwent corrective surgery for cervical deformity. Multivariate analysis was utilized. RESULTS:A total of 95 patients were included: 49 who underwent 3CO and 46 who underwent SPO. Twelve of the SPO patients underwent an anterior release procedure. The patients' mean age was 63.2 years, and 60.0% of the patients were female. All preoperative radiographic parameters showed significant correction postoperatively: cSVA (6.2 cm vs 4.5 cm [preoperative vs postoperative values], p < 0.001), cervical lordosis (6.8° [kyphosis] vs -7.5°, p < 0.001), and T1 slope (40.9° and 35.2°, p = 0.026). The overall complication rate was 37.9%, and postoperative neurological deficits were seen in 16.8% of patients. The surgical and medical complication rates were 17.9% and 23.2%, respectively. Overall, complication rates were higher in patients who underwent 3CO compared to those who underwent SPO, but this was not statistically significant (total complication rate 42.9% vs 32.6%, p = 0.304; surgical complication rate 18.4% vs 10.9%, p = 0.303; and new neurological deficit rate 20.4% vs 13.0%, p = 0.338). Medical complication rates were similar between the two groups (22.4% [3CO] vs 23.9% [SPO], p = 0.866). Independent risk factors for surgical complications included male sex (OR 10.88, p = 0.014), cSVA > 8 cm (OR 10.36, p = 0.037), and kyphosis > 20° (OR 9.48, p = 0.005). Combined anterior-posterior surgery was independently associated with higher odds of medical complications (OR 10.30, p = 0.011), and preoperative kyphosis > 20° was an independent risk factor for neurological deficits (OR 2.08, p = 0.011). CONCLUSIONS:There was no significant difference in complication rates between 3CO and SPO for cervicothoracic deformity correction, but absolute surgical and neurological complication rates for 3CO were higher. A preoperative cSVA > 8 cm was a risk factor for surgical complications, and kyphosis > 20° was a risk factor for both surgical and neurological complications. Additional studies are warranted on this topic.

OBJECTIVE:The benefits and utility of routine neuromonitoring with motor and somatosensory evoked potentials during lumbar spine surgery remain unclear. This study assesses measures of performance and utility of transcranial motor evoked potentials (MEPs) during lumbar pedicle subtraction osteotomy (PSO). METHODS:This is a retrospective study of a single-surgeon cohort of consecutive adult spinal deformity (ASD) patients who underwent lumbar PSO from 2006 to 2016. A blinded neurophysiologist reviewed individual cases for MEP changes. Multivariate analysis was performed to determine whether changes correlated with neurological deficits. Measures of performance were calculated. RESULTS:A total of 242 lumbar PSO cases were included. MEP changes occurred in 38 (15.7%) cases; the changes were transient in 21 cases (55.3%) and permanent in 17 (44.7%). Of the patients with permanent changes, 9 (52.9%) had no recovery and 8 (47.1%) had partial recovery of MEP signals. Changes occurred at a mean time of 8.8 minutes following PSO closure (range: during closure to 55 minutes after closure). The mean percentage of MEP signal loss was 72.9%. The overall complication rate was 25.2%, and the incidence of new neurological deficits was 4.1%. On multivariate analysis, MEP signal loss of at least 50% was not associated with complication (p = 0.495) or able to predict postoperative neurological deficits (p = 0.429). Of the 38 cases in which MEP changes were observed, the observation represented a true-positive finding in only 3 cases. Postoperative neurological deficits without MEP changes occurred in 7 cases. Calculated measures of performance were as follows: sensitivity 30.0%, specificity 84.9%, positive predictive value 7.9%, and negative predictive value 96.6%. Regarding the specific characteristics of the MEP changes, only a signal loss of 80% or greater was significantly associated with a higher rate of neurological deficit (23.0% vs 0.0% for loss of less than 80%, p = 0.021); changes of less than 80% were not associated with postoperative deficits. CONCLUSIONS:Neuromonitoring has a low positive predictive value and low sensitivity for detecting new neurological deficits. Even when neuromonitoring is unchanged, patients can still have new neurological deficits. The utility of transcranial MEP monitoring for lumbar PSO remains unclear but there may be advantages to its use.

Study DesignRetrospective cohort study.ObjectivesTo characterize longitudinal durability of cervical deformity (CD) correction, identify predictors of alignment failure, and define failure mechanism timing across the first postoperative year.Methodsof 155 operative CD patients in a prospectively maintained multicenter database, 89 had complete four-timepoint radiographic follow-up. Well-alignment was defined as cSVA <4 cm. Patients were grouped as A (maintained), B (corrected then deteriorated), or C (never aligned). Analyses included Cox regression (n=47, 17 events), Kaplan-Meier with restricted mean survival time (RMST), and mixed-effects logistic regression across four timepoints (n=356; ICC=0.36). Concurrent thoracolumbar deformity was excluded.ResultsWell-aligned proportion fell from 48.3% at 3 months to 33.7% at 1 year (A=34%, B=19%, C=47%). DJK was most strongly associated with alignment loss (HR 5.21, 95% CI 1.94-13.98; OR 0.09), with alignment maintained 4.1 versus 9.8 months (RMST difference 5.7, p=0.001). Lower postoperative cSVA paradoxically increased failure hazard (HR 0.58/10 mm, p=0.002). Older patients deteriorated faster (Time×Age OR 0.88, p=0.022). Failure mechanisms shifted from DJK at 3 months (50%) to PJK at 6 months (75%) to global compensation loss at 1 year (71%). No surgical parameters differed between groups.ConclusionsFewer than one-third of patients maintain alignment at 1 year. DJK, advanced age, and lower postoperative cSVA were most strongly associated with failure (17 events; limited precision). Mechanisms appeared to shift from junctional failure early to global decompensation late. Alignment loss was not accompanied by significant 1-year NDI or EQ-5D differences, framing radiographic deterioration as an early surveillance marker rather than clinical failure. Individualized risk stratification and surveillance are supported.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Anterior lumbar interbody fusion (ALIF) is an important technique offering biomechanical advantages including improved disk height restoration, correction of sagittal and coronal imbalance, and improved fusion. Although generally safe, vascular injury remains a serious complication. Specific vascular injury mechanisms, management, and outcomes are insufficiently reported. We seek to better characterize the incidence, mechanism, management, and sequelae of intraoperative vascular injuries during ALIF. METHODS:We performed a retrospective single-center study of adult patients undergoing ALIF between 2018 and 2022. All exposures were performed by a vascular surgeon. Data analyzed included patient demographics, operative characteristics, and vascular complications (classified as major or minor). The primary outcomes were the incidence of vascular injury and postoperative venous thromboembolism (VTE). Statistical analyses included χ2 testing and logistic regression. RESULTS:Of 418 patients, 26 (6.2%) sustained intraoperative vascular injuries, with 4 (1.0%) classified as major. Injuries were predominantly venous (n = 25), most frequently involving the left common iliac vein during L4-L5 exposure. One arterial dissection required stenting. Postoperative VTE occurred in 11 patients (2.6%); notably, 45.5% of these patients had sustained an intraoperative vascular injury. Vascular injury was a strong independent predictor of VTE (odds ratio [OR]: 15.9; P < .001; 95% CI: 4.3-58.8). The number of levels fused was significantly associated with both vascular injury (OR: 1.76; P = .007; 95% CI: 1.16-2.66) and VTE (OR: 1.91; P = .031; 95% CI: 1.03-3.42). No association was found between vascular complications and previous abdominal surgery, body mass index, revision surgery, age older than 50, spinal deformity, or sex. There was 0% perioperative mortality. CONCLUSION/CONCLUSIONS:Vascular complications during ALIF are infrequent but significantly elevate the risk of postoperative VTE. Injuries cluster at the L4-L5 level and often involve the left common iliac vein. Preoperative planning, careful surgical technique, and experienced vascular access support are critical to minimizing complications.

OBJECTIVE:Spinal meningiomas (SMs) are common primary spinal tumors for which surgery is considered the first-line treatment when safe and feasible. The ability to extrapolate the tumor grade from preoperative imaging may significantly inform early patient expectation-setting regarding recurrence. Building on radiomics studies in cranial meningiomas, the authors aimed to construct a benchmark radiomics model to preoperatively identify the histological grade of SMs. METHODS:Institutional surgical records from May 2012 to November 2025 were queried for pathology-confirmed meningiomas below the foramen magnum, with preoperative contrast-enhanced imaging available for segmentation. SMs were classified as low-grade (WHO grade 1) and high-grade (WHO grade 2 tumors and grade 1 tumors with atypia). Tumors were manually segmented, and features were extracted using the PyRadiomics software package. An ensemble model of k-nearest neighbors, random forest, and support vector machine classifiers was trained using nested cross-validation on a subset of 10 features to differentiate tumor grades. Clinical data for the cohort were also extracted, and disease control in an adjunctive clinical series was assessed. RESULTS:Seventy-four patients were included in radiomics analysis, with an area under the receiver operating characteristic curve of 0.879 and a mean F1 score of 0.748. The model's top 5 features were all texture features that differed significantly (p < 0.05) across low- and high-grade SMs. These included measures of tumor textural and contrast-enhancement heterogeneity, with overlap with features reported in radiomics models for histological grading of intracranial meningiomas. Fifty-five patients with a median radiographic follow-up of 22.2 (range 1.9-86.4) months remained for clinical analysis after exclusion of patients with less than 1 month of follow-up and syndromic meningiomas. Four recurrences occurred at a median of 20.8 (range 1.8-41.8) months. High-grade tumor pathology did not significantly impact progression-free survival (p = 0.682, log-rank test; Cox regression high vs low grade hazard ratio [HR] 0.62, 95% CI 0.06-6.11, p = 0.685). Subtotal resection was associated with poorer progression-free survival than gross-total resection (p = 0.004, log-rank test; Cox regression subtotal vs gross-total resection HR 10.62, 95% CI 1.46-77.05, p = 0.019). These findings remain contextualized within a relatively limited follow-up window and small recurrence event count, suggesting a need to characterize the interplay between tumor grade and extent of resection as drivers of local disease control in SMs. CONCLUSIONS:A preoperative radiomics model can stratify high-grade SMs using open-source tools applied to single-institution data.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Intradural extramedullary spinal tumors (IDEMs) are ideally managed with gross total resection (GTR) for optimal local disease control in the absence of established adjuvant regimens. In this retrospective cohort study, we investigated the utility of morphology-based analysis of optimal IDEM resection quality compared with current linear measurement benchmarks. METHODS:Tumors were manually segmented from preoperative contrast-enhanced MRI. Morphological features of sphericity, elongation, and volume were extracted from masks, along with manual anteroposterior, craniocaudal, and transverse linear measurements. Optimal resection was defined as Simpson Grade 1 or 2 for meningiomas or en bloc GTR for myxopapillary ependymomas (MPEs) and was predicted for dorsal and ventral spinal meningiomas plus conus and nonconus MPEs. RESULTS:We identified 103 tumors, including 71 meningiomas and 32 MPEs. Linear measurement did not reliably predict optimal resection across anatomic subtypes of meningiomas or MPEs (all P > .05). Instead, optimal resection was determined by higher sphericity across meningiomas and, specifically, dorsal meningiomas (optimal resection median 0.80 (IQR: 0.77-0.82) vs suboptimal 0.76 (0.72-0.77), P = .027). Shape features were not predictive in ventral meningiomas. En bloc GTR was limited to nonconus MPEs, in which sphericity again emerged as a predictor (0.74 (0.69-0.77) for en bloc vs 0.68 (0.64-0.72) for piecemeal, P = .047), likely reflecting resectability for encapsulated tumors. After excluding patients with <1 year of surveillance to determine nonrecurrence, 62 patients without genetic syndromes remained for recurrence analysis with a median follow-up of 36.1 months. Optimal resection was associated with significantly lower recurrence (optimal 8.6% vs suboptimal 29.6%, P = .045). This protective effect remained, although statistically insignificant after adjusting for adjuvant radiation and tumor grade (recurrence odds ratio = 0.22, 95% CI: 0.04-1.07, P = .077). CONCLUSION/CONCLUSIONS:IDEM tumor morphology is predictive of optimal resection for dorsal meningiomas and nonconus MPEs, whereas linear measurements offer less consistent predictive value. Morphological assessment is feasible with standard MRI and may be further automated.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Myxopapillary ependymomas (MPE) and intradural lumbosacral schwannomas may be challenging to distinguish based on presenting characteristics and preoperative imaging. Accurate differentiation is crucial, as MPEs carry a risk of cerebrospinal fluid dissemination and warrant earlier intervention, a more tailored surgical strategy, consideration for adjuvant radiation, and frequent surveillance. Here, we describe our institutional experience with these tumors and develop a radiomics-based machine learning model to help distinguish them on preoperative imaging. METHODS:Institutional surgical records from 2011 to 2025 were queried and clinical data were extracted for the retrospective cohort analysis. Tumors were manually segmented in ITK-Snap from T1 postcontrast images, and radiomics features were extracted using the PyRadiomics package. An ensemble of random forest, k-nearest neighbors, and naive Bayes classifiers was trained on a subset of radiomics features using nested cross-validation. RESULTS:< .001) in MPEs, likely due to longitudinal tumor growth along the filum. Excluding scoliotic patients did not significantly alter discrimination, suggesting robustness to vertebral column malalignment that may coexist with intradural tumors. CONCLUSION/CONCLUSIONS:A radiomics-based machine learning model demonstrated excellent discriminative ability between MPE and lumbosacral schwannoma, achieving high accuracy and robustness to vertebral alignment variations. These results suggest that radiomics-based models may be developed into a useful tool for preoperative planning and patient counseling.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Multiple-choice questions are the primary assessment format for neurosurgical board certification. Creating high-quality examination questions requires significant expert time and resources. The goal of this study was to develop an automated system to generate board-style neurosurgical multiple-choice questions using state-of-the-art vision-language models and compare their quality with authentic self-assessment questions. METHODS:articles. We generated 89 587 synthetic questions: 45 689 with GPT-4o and 43 898 with Claude. Each question was associated with a single image extracted from the articles' figures. We evaluated the quality of synthetic questions through 5 surveys comparing 20 synthetic questions (10 from each model) with 10 authentic questions from the Self-Assessment for Neurological Surgeons (SANS) question bank. Each survey was completed by a neurosurgery resident and an attending who guessed the source [human vs artificial intelligence (AI)-generated] and rated suitability for board examination use. We also evaluated the question-answering performance of the generalist GPT-4o and the specialized CNS-Obsidian. RESULTS:). CONCLUSION/CONCLUSIONS:Although quality gaps exist between AI-generated and human-created neurosurgical board examination questions, our approach demonstrates the potential of vision-language models to augment assessment development in specialized medical fields, reducing the burden on examination boards and credentialing organizations.