Clarke, Michelle J.

OBJECTIVE Chordomas are rare tumors from notochordal remnants and account for 1%–4% of all primary bone malignancies, often arising from the clivus and sacrum. Despite margin-negative resection and postoperative radiotherapy, chordomas often recur. Further, immunohistochemical (IHC) markers have not been assessed as predictive of chordoma recurrence. The authors aimed to identify the IHC markers that are predictive of postoperative long-term (≥ 1 year) chordoma recurrence by using trained multiple tree-based machine learning (ML) algorithms. METHODS The authors reviewed the records of patients who had undergone treatment for clival and spinal chordomas between January 2017 and June 2021 across the Mayo Clinic enterprise (Minnesota, Florida, and Arizona). Demographics, type of treatment, histopathology, and other relevant clinical factors were abstracted from each patient record. Decision tree and random forest classifiers were trained and tested to predict long-term recurrence based on unseen data using an 80/20 split. RESULTS One hundred fifty-one patients diagnosed and treated for chordomas were identified: 58 chordomas of the clivus, 48 chordomas of the mobile spine, and 45 chordomas sacrococcygeal in origin. Patients diagnosed with cervical chordomas were the oldest among all groups (58 ± 14 years, p = 0.009). Most patients were male (n = 91, 60.3%) and White (n = 139, 92.1%). Most patients underwent resection with or without radiation therapy (n = 129, 85.4%). Subtotal resection followed by radiation therapy (n = 51, 33.8%) was the most common treatment modality, followed by gross-total resection then radiation therapy (n = 43, 28.5%). Multivariate analysis showed that S100 and pan-cytokeratin are more likely to predict the increase in the risk of postoperative recurrence (OR 3.67, 95% CI 1.09–12.42, p= 0.03; and OR 3.74, 95% CI 0.05–2.21, p = 0.02, respectively). In the decision tree analysis, a clinical follow-up > 1897 days was found in 37% of encounters and a 90% chance of being classified for recurrence (accuracy = 77%). Random forest analysis (n = 500 trees) showed that patient age, type of surgical treatment, location of tumor, S100, pan-cytokeratin, and EMA are the factors predicting long-term recurrence. CONCLUSIONS The IHC and clinicopathological variables combined with tree-based ML tools successfully demonstrated a high capacity to identify recurrence patterns with an accuracy of 77%. S100, pan-cytokeratin, and EMA were the IHC drivers of recurrence. This shows the power of ML algorithms in analyzing and predicting outcomes of rare conditions of a small sample size.

OBJECTIVE The purpose of this study was to analyze risk factors for sacral fracture following noninstrumented partial sacral amputation for en bloc chordoma resection. METHODS A multicenter retrospective chart review identified patients who underwent noninstrumented partial sacral amputation for en bloc chordoma resection with pre- and postoperative imaging. Hounsfield units (HU) were measured in the S1 level. Sacral amputation level nomenclature was based on the highest sacral level with bone removed (e.g., S1 foramen amputation at the S1–2 vestigial disc is an S2 sacral amputation). Variables collected included basic demographics, patient comorbidities, surgical approach, preoperative radiographic details, neoadjuvant and adjuvant radiation therapy, and postoperative sacral fracture data. RESULTS A total of 101 patients (60 men, 41 women) were included; they had an average age of 69 years, BMI of 29 kg/m2, and follow-up of 60 months. The sacral amputation level was S1 (2%), S2 (37%), S3 (44%), S4 (9%), and S5 (9%). Patients had a posterior-only approach (77%) or a combined anterior–posterior approach (23%), with 10 patients (10%) having partial sacroiliac (SI) joint resection. Twenty-seven patients (27%) suffered a postoperative sacral fracture, all occurring between 1 and 7 months after the index surgery. Multivariable logistic regression analysis demonstrated S1 or S2 sacral amputation level (p = 0.001), combined anterior–posterior approach (p = 0.0064), and low superior S1 HU (p = 0.027) to be independent predictors of sacral fracture. The fracture rate for patients with superior S1 HU < 225, 225–300, and > 300 was 38%, 15%, and 9%, respectively. An optimal superior S1 HU cutoff of 300 was found to maximize sensitivity (89%) and specificity (42%) in predicting postamputation sacral fracture. In addition, the fracture rate for patients who underwent partial SI joint resection was 100%. CONCLUSIONS Patients with S1 or S2 partial sacral amputations, a combined anterior–posterior surgical approach, low superior S1 HU, and partial SI joint resection are at higher risk for postoperative sacral fracture following en bloc chordoma resection and should be considered for spinopelvic instrumentation at the index procedure.

Extradural malignant primary spinal tumors are rare and outcome data, especially for younger patients, is limited. In a worldwide (11 centers) study (Predictors of Mortality and Morbidity in the Surgical Management of Primary Tumors of the Spine study; ClinicalTrials.gov Identifier NCT01643174) by the AO Spine Knowledge Forum Tumor, patients surgically treated for primary tumors of the spine between 1992 and 2012, were retrospectively analyzed from a prospective database of their medical history. Medical history, tumor characteristics, diagnostics, treatments, cross-sectional survival, and local recurrences were analyzed. Sixty-eight cases (32 f; 36 m), at an average age of 18.6 ± 4.7 years at the time of diagnosis, were identified (median follow-up 2.9 years). The most common entities were Ewing’s sarcoma (42.6%). Of the patients, 28% had undergone previous spine tumor surgery in another center (84% with intralesional margins). Resection was considered “Enneking appropriate” (EA) in 47.8% of the cases. Of the patients, 77.9% underwent chemotherapy and 50% radiotherapy. A local recurrence occurred in 36.4%. Over a third of patients died within a 10-year follow-up period. Kaplan-Meier-analysis demonstrated statistically significant overall survival (p = 0.007) and local recurrence rates (p = 0.042) for tumors treated with EA surgery versus Enneking inappropriate surgery. Aggressive resection of extradural primary malignant spinal tumors combined with adjuvant therapy reveals low local recurrence rates and better outcomes overall in younger patients.

Extradural primary spinal tumors were retrospectively analyzed from a prospective database of 1495 cases. All subjects with benign primary tumors under the age of 25 years, who were enrolled between 1990 and 2012 (Median FU was 2.4 years), were identified. Patient- and case-related characteristics were collected and statistically analyzed. Results: 161 patients (66f;95m; age 17.0 ± 4.7 years at time of diagnosis) were identified. The most common tumors were osteoblastomas n = 53 (32.9%), osteoid osteomas n = 45 (28.0%), and aneurysmal bone cysts n = 32 (19.9%). The tumor grade, according to the Enneking Classification S1/S2/S3, was 14/73/74 (8.7/45.3/46.0%), respectively. Tumor-related pain was present in 156 (96.9%) patients. Diagnosis was achieved by biopsies in 2/3 of the cases. Spinal fixation was used in >50% of the cases. Resection was Enneking appropriate in n = 100 (62.1%) of cases. Local recurrence occurred in 21 (13.1%) patients. Two patients died within a 10-year follow-up period. Conclusion: This is one of the largest international multicenter cohorts of young patients surgically treated for benign spinal tumors. The heterogenic young patient cohort presented at a mid-term follow-up without a correlation between the grade of aggressiveness in resection and local recurrence rates. Further prospective data are required to identify prognostic factors that determine oncological and functional outcomes for young patients suffering from these rare tumors.

Abstract OBJECTIVE We aim to describe a case of follicular lymphoma that presented as a durally-based thoracic spine lesion manifested as rapidly progressive back pain and meningismus. BACKGROUND Follicular lymphoma is one of the most common forms of non-Hodgkin’s lymphoma; however, it is rare for follicular lymphoma to present as a spinal meningeal mass lesion. METHODS This is a case report and review of literature. RESULTS A 38-year-old man developed thoracic back pain that progressed over one month with associated severe focal tenderness over his mid to lower thoracic spine. He developed intermittent numbness of the bilateral lower extremities, nuchal rigidity, difficulty sleeping, and night sweats. An MRI of the thoracic spine demonstrated a dorsal intradural, extramedullary enhancing lesion from T6-T9 extending outside the spinal canal. Dural thickening across the entire circumference of the spinal cord was noted. CT-guided biopsy of the thoracic lesion was performed, and pathology was consistent with follicular lymphoma. FDG PET: CT demonstrated no systemic disease. Bone marrow biopsy was negative for malignancy. Symptoms resolved with dexamethasone therapy. He was treated with bendamustine and rituximab with follow up PET: CT two months later demonstrating a complete response. DISCUSSION This case illustrates an unusual presentation of follicular lymphoma as a spinal meningeal mass lesion. Though rare, lymphoma should be included in the differential diagnosis of a dural mass lesion. Prompt diagnosis and initiation of treatment can lead to complete response and resolution of symptoms.

OBJECTIVE Structured performance evaluations are important for the professional development and personal growth of resident learners. This process is formalized by the Accreditation Council for Graduate Medical Education milestones assessment system. The primary aim of this study was to understand the current feedback delivery mechanism by exploring the culture of feedback, the mechanics of delivery, and the evaluation of the feedback itself. METHODS Face-to-face interviews were conducted with 10 neurosurgery residents exploring their perceptions of summative feedback. Coded data were analyzed qualitatively for overriding themes using the matrix framework method. A priori themes of definition of feedback, feedback delivery, and impact of feedback were combined with de novo themes discovered during analysis. RESULTS Trainees prioritized formative over summative feedback. Summative and milestone feedback were criticized as being vague, misaligned with practice, and often perceived as erroneous. Barriers to implementation of summative feedback included perceived veracity of feedback, high interrater variability, and the inconstant adoption of a developmental progression model. Gender bias was noted in degree of feedback provided and language used. CONCLUSIONS Trainee perception of feedback provided multiple areas of improvement. This paper can serve as a baseline to study improvements in the milestone feedback process and optimize learning.

OBJECTIVE Patients with ankylosing spinal disorders (ASDs), including ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH), have been shown to experience significantly increased rates of postoperative complications. Despite this, very few risk stratification tools have been validated for this population. As such, the purpose of this study was to identify predictors of adverse events and mortality in ASD patients undergoing surgery for 3-column fractures. METHODS All adult patients with a documented history of AS or DISH who underwent surgery for a traumatic 3-column fracture between 2000 and 2020 were identified. Perioperative variables, including comorbidities, time to diagnosis, and number of fused segments, were collected. Three instruments, including the Charlson Comorbidity Index (CCI), modified frailty index (mFI), and Injury Severity Score (ISS), were computed for each patient. The primary outcomes of interest included 1-year mortality, as well as postoperative complications. RESULTS A total of 108 patients were included, with a mean ± SD age of 73 ± 11 years. Of these, 41 (38%) experienced at least 1 postoperative complication and 22 (20.4%) died within 12 months after surgery. When the authors controlled for potential known confounders, the CCI score was significantly associated with postoperative adverse events (OR 1.20, 95% CI 1.00–1.42, p = 0.045) and trended toward significance for mortality (OR 1.19, 95% CI 0.97–1.45, p = 0.098). In contrast, mFI score and ISS were not significantly predictive of either outcome. CONCLUSIONS Complications in spine trauma patients with ASD may be driven by comorbidity burden rather than operative or injury-related factors. The CCI may be a valuable tool for the evaluation of this unique population.