Delphi consensus on stereotactic ablative radiotherapy for oligometastatic and oligoprogressive renal cell carcinoma-a European Society for Radiotherapy and Oncology study endorsed by the European Association of Urology.

The purpose of this European Society for Radiotherapy and Oncology (ESTRO) project, endorsed by the European Association of Urology, is to explore expert opinion on the management of patients with oligometastatic and oligoprogressive renal cell carcinoma by means of stereotactic ablative radiotherapy (SABR) on extracranial metastases, with the aim of developing consensus recommendations for patient selection, treatment doses, and concurrent systemic therapy. A questionnaire on SABR in oligometastatic renal cell carcinoma was prepared by a core group and reviewed by a panel of ten prominent experts in the field. The Delphi consensus methodology was applied, sending three rounds of questionnaires to clinicians identified as key opinion leaders in the field. At the end of the third round, participants were able to find consensus on eight of the 37 questions. Specifically, panellists agreed to apply no restrictions regarding age (25 [100%) of 25) and primary renal cell carcinoma histology (23 [92%] of 25) for SABR candidates, on the upper threshold of three lesions to offer ablative treatment in patients with oligoprogression, and on the concomitant administration of immune checkpoint inhibitor. SABR was indicated as the treatment modality of choice for renal cell carcinoma bone oligometatasis (20 [80%] of 25) and for adrenal oligometastases 22 (88%). No consensus or major agreement was reached regarding the appropriate schedule, but the majority of the poll (54%-58%) retained the every-other-day schedule as the optimal choice for all the investigated sites. The current ESTRO Delphi consensus might provide useful direction for the application of SABR in oligometastatic renal cell carcinoma and highlight the key areas of ongoing debate, perhaps directing future research efforts to close knowledge gaps.

The role of spine stereotactic radiosurgery for patients with breast cancer metastases.

PURPOSE: Breast cancer that metastasizes to the spine is associated with low quality of life and poor survival. Radiosurgery has an increasing role in this patient population. This single-institution (2003-2023) study analyzes clinical outcomes and prognostic factors for patients who underwent spinal stereotactic radiosurgery (SSRS) for metastatic breast cancer. METHODS: Ninety patients (155 unique breast cancer spinal metastases) were treated with SSRS. The median age was 57 years (range: 35-88), and the median KPS was 80 (range: 40-100). Forty-two (27%) lesions were managed surgically prior to radiosurgery. At SSRS, 75 (48%) lesions impinged or compressed the spinal cord per the epidural spinal cord scale (ESCC). Seventy-nine (51%) lesions were categorized as potentially unstable or unstable by the Spinal Instability Neoplastic Score (SINS). RESULTS: The median follow-up was 15 months (range: 1-183). The median single-session tumor volume was 25.4 cc (range: 2-197), and the median single-fraction prescription dose was 17 Gy (range: 12-25). Seven (5%) lesions locally progressed. The 1-, 2-, and 5-year local control rates were 98%, 97%, and 92%, respectively. The median overall survival (OS) for the cohort was 32 months (range: 2-183). The 1-, 2-, and 5-year OS rates were 72%, 53%, and 30%, respectively. On univariate analysis, KPS ≥ 80 (p = 0.009, HR: 0.51, 95% CI: 0.31-0.84) was associated with improved OS. Patient-reported pain improved (68%), remained stable (29%), or worsened (3%) following radiosurgery. Fifteen (10%) radiation-induced toxicities were reported. CONCLUSIONS: Spinal radiosurgery is a safe and highly effective long-term treatment modality for metastases to the spine that originate from breast cancer.

Fluorescence-guided resection of intradural spinal tumors: a systematic review and meta-analysis.

Intradural spinal tumors present significant challenges due to involvement of critical motor and sensory tracts. Achieving maximal resection while preserving functional tissue is therefore crucial. Fluorescence-guided surgery aims to improve resection accuracy and is well studied for brain tumors, but its efficacy has not been fully assessed for spinal tumors. This meta-analysis aims to delineate the efficacy of fluorescence guidance in intradural spinal tumor resection. The authors performed a systematic review in four databases. We included studies that have utilized fluorescence agents, 5-aminolevulinic acid (5-ALA) or sodium fluorescein, for the resection of intradural spinal tumors. A meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A total of 12 studies involving 552 patients undergoing fluorescence-guided intradural spinal tumor resection were included. Meningiomas demonstrated a 98% fluorescence rate and were associated with a homogenous florescence pattern; however, astrocytomas had variable fluorescence rate with pooled proportion of 70%. There was no significant difference in gross total resection (GTR) rates between fluorescein and 5-ALA (94% vs 84%, p = .22). Pre-operative contrast enhancement was significantly associated with intraoperative fluorescence with fluorescein. Intramedullary tumors with positive intraoperative fluorescence were significantly associated with higher GTR rates (96% vs 73%, p = .03). Utilizing fluorescence guidance during intradural spinal tumor resection holds promise of improving intraoperative visualization for specific intradural spinal tumors. Meningiomas and ependymomas have the highest fluorescence rates especially with sodium fluorescein; on the other hand, astrocytomas have variable fluorescence rates with no superiority of either agent. Positive fluorescence of intramedullary tumors is associated with a higher degree of resection.

Percutaneous balloon kyphoplasty in the treatment of vertebral compression fractures: a single-center analysis of pain and quality of life outcomes.

BACKGROUND: Vertebral body compression fractures are one of the most common causes of disability and morbidity, especially among the elderly population. The present study was performed in order to evaluate the effect of percutaneous balloon kyphoplasty (BKP) on patients' pain and quality of life (QOL) in Iran. METHODS: The study was conducted on a consecutive series of 54 patients with symptomatic vertebral compression fractures who failed conservative management between 2014 and 2017. A quasi-experimental design was employed in which the pain severity, quality of life, and kyphotic angle were measured before and 3 and 12 months after the PBK procedure. Pain and quality of life outcomes were determined using a Visual Analogue Scale (VAS) for Pain and the 12-Item Short Form Health Survey (SF-12) for QOL. RESULTS: Excellent improvement in VAS was documented at 3 and 12 months after the BKP procedure (p = 0.001). Improvement at 3 months was maintained through the 12 months follow-up period. A statistically significant improvement in QOL was documented at 3 months after BKP that continued to improve through 12 months follow-up. The mean kyphotic angle before PBK was 19.4 ± 5.3 degrees which after 3 months improved to 12.8 ± 3.1 degrees; this reduction was significant (p < 0.001). No new fractures occurred during the follow-up period. CONCLUSION: Balloon kyphoplasty was determined to be a safe and successful method for treating symptomatic vertebral compression fractures. It leads to significant pain relief, an improvement in self-reported QOL measures, and correction in kyphotic deformity.

Craniometrical imaging and clinical findings of adult Chiari malformation type 1 before and after posterior fossa decompression surgery with duraplasty.

Background: Posterior fossa decompression both with and without duraplasty are accepted treatments for symptomatic adult patients with Chiari Malformations Type 1 (CM-1). There is still debate of the superiority of one technique over the other. The purpose of this study was to determine the clinical and craniometrical imaging outcomes of a series of patients who underwent posterior fossa decompression with duraplasty. Materials and methods: All adult patients with symptomatic CM-1 operated at a single institution with a minimum of 6 months follow-up were enrolled prospectively. Clinical outcomes and craniometrical parameters based upon MR imaging pre- and post-surgery were analyzed. Results: A series of 33 consecutive patients who met the inclusion criteria were enrolled; mean age of 33.93 ± 10 years (range 14-56 years). The most common preoperative complaint was headache. The most common clinical sign was sensory dysfunction which was relieved or improved in 63% of patients. The mean syringomyelia size had a significant reduction after the surgery (p = .01). The mean tonsillar descent also had significant reduction (p = .00). The mean McRae line length before the surgery and after that were 33.4 and 53.1 mm respectively that this change was not statistically significant (p = .42). The odontoid process parameters had no significant changes after surgery. Conclusions: Posterior fossa decompression surgery with duraplasty can improve both clinical and imaging outcomes such as syringomyelia size and tonsillar descent for patients with symptomatic CM-1. However, no significant difference was found in craniometrical parameters before and after the surgery.

Stereotactic radiosurgery for intradural spine tumors using cone-beam CT image guidance.

OBJECTIVE Cone-beam CT (CBCT) image guidance technology has been widely adopted for spine radiosurgery delivery. There is relatively little experience with spine radiosurgery for intradural tumors using CBCT image guidance. This study prospectively evaluated a series of intradural spine tumors treated with radiosurgery. Patient setup accuracy for spine radiosurgery delivery using CBCT image guidance for intradural spine tumors was determined. METHODS Eighty-two patients with intradural tumors were treated and prospectively evaluated. The positioning deviations of the spine radiosurgery treatments in patients were recorded. Radiosurgery was delivered using a linear accelerator with a beam modulator and CBCT image guidance combined with a robotic couch that allows positioning correction in 3 translational and 3 rotational directions. To measure patient movement, 3 quality assurance CBCTs were performed and recorded in 30 patients: before, halfway, and after the radiosurgery treatment. The positioning data and fused images of planning CT and CBCT from the treatments were analyzed to determine intrafraction patient movements. From each of 3 CBCTs, 3 translational and 3 rotational coordinates were obtained. RESULTS The radiosurgery procedure was successfully completed for all patients. Lesion locations included cervical (22), thoracic (17), lumbar (38), and sacral (5). Tumor histologies included schwannoma (27), neurofibromas (18), meningioma (16), hemangioblastoma (8), and ependymoma (5). The mean prescription dose was 17 Gy (range 12-27 Gy) delivered in 1-3 fractions. At the halfway point of the radiation, the translational variations and standard deviations were 0.4 ± 0.5, 0.5 ± 0.8, and 0.4 ± 0.5 mm in the lateral (x), longitudinal (y), and anteroposterior (z) directions, respectively. Similarly, the variations immediately after treatment were 0.5 ± 0.4, 0.5 ± 0.6, and 0.6 ± 0.5 mm along x, y, and z directions, respectively. The mean rotational angles were 0.3° ± 0.4°, 0.3° ± 0.4°, and 0.3° ± 0.4° along yaw, roll, and pitch, respectively, at the halfway point and 0.5° ± 0.5°, 0.4° ± 0.5°, and 0.2° ± 0.3° immediately after treatment. CONCLUSIONS Radiosurgery offers an alternative treatment option for intradural spine tumors in patients who may not be optimal candidates for open surgery. CBCT image guidance for patient setup for spine radiosurgery is accurate and successful in patients with intradural tumors.

Posterior lumbar dynamic stabilization instead of arthrodesis for symptomatic adjacent-segment degenerative stenosis: description of a novel technique.

OBJECTIVE The development of symptomatic adjacent-segment disease (ASD) is a well-recognized consequence of lumbar fusion surgery. Extension of a fusion to a diseased segment may only lead to subsequent adjacent-segment degeneration. The authors report the use of a novel technique that uses dynamic stabilization instead of arthrodesis for the surgical treatment of symptomatic ASD following a prior lumbar instrumented fusion. METHODS A cohort of 28 consecutive patients was evaluated who developed symptomatic stenosis immediately adjacent to a previous lumbar instrumented fusion. All patients had symptoms of neurogenic claudication refractory to nonsurgical treatment and were surgically treated with decompression and dynamic stabilization instead of extending the fusion construct using a posterior lumbar dynamic stabilization system. Preoperative symptoms, visual analog scale (VAS) pain scores, and perioperative complications were recorded. Clinical outcome was gauged by comparing VAS scores prior to surgery and at the time of last follow-up. RESULTS The mean follow-up duration was 52 months (range 17-94 months). The mean interval from the time of primary fusion surgery to the dynamic stabilization surgery was 40 months (range 10-96 months). The mean patient age was 51 years (range 29-76 years). There were 19 (68%) men and 9 (32%) women. Twenty-three patients (82%) presented with low-back pain at time of surgery, whereas 24 patients (86%) presented with lower-extremity symptoms only. Twenty-four patients (86%) underwent operations that were performed using single-level dynamic stabilization, 3 patients (11%) were treated at 2 levels, and 1 patient underwent 3-level decompression and dynamic stabilization. The most commonly affected and treated level (46%) was L3-4. The mean preoperative VAS pain score was 8, whereas the mean postoperative score was 3. No patient required surgery for symptomatic degeneration rostral to the level of dynamic stabilization during the follow-up period. CONCLUSIONS The use of posterior lumbar dynamic stabilization may offer a valid and safe option for the management of patients who develop ASD rostral to a previously instrumented arthrodesis. The technique may serve as an alternative to multilevel arthrodesis in this patient population. By implanting a dynamic stabilization device instead of an extension of a rigid construct, this might translate into a reduction in the development of yet another level of ASD.

Histopathological examination of spine tumors after treatment with radiosurgery.

OBJECTIVE Increased survival time after diagnosis of neoplastic disease has resulted in a gradual increase in spine tumor incidence. Radiosurgery is frequently a viable alternative to operative management in a population with severe medical comorbidities. The authors sought to assess the histopathological consequences of radiosurgery in the subset of patients progressing to operative intervention. METHODS Eighteen patients who underwent radiosurgery for spine tumors between 2008 and 2014 subsequently progressed to surgical treatment. A histopathological examination of these cases was performed. Indications for surgery included symptomatic compression fractures, radiographic instability, and symptoms of cord or cauda equina compression. Biopsy samples were obtained from the tumor within the radiosurgical zone in all cases and were permanently fixated. Viable tumor samples were stained for Ki 67. RESULTS Fifteen patients had metastatic lesions and 3 patients had neurofibromas. The mean patient age was 57 years. The operative indication was symptomatic compression in 10 cases (67%). The most frequent metastatic lesions were breast cancer (4 cases), renal cell carcinoma (3), prostate cancer (2), and endometrial cancer (2). In 9 (60%) of the 15 metastatic cases, histological examination of the lesions showed minimal evidence of inflammation. Viable tumor at the margins of the radiosurgery was seen in 9 (60%) of the metastatic cases. Necrosis in the tumor bed was frequent, as was fibrotic bone marrow. Vascular ectasia was seen in 2 of 15 metastatic cases, but sclerosis with ectasia was frequent. No evidence of malignant conversion was seen in the periphery of the lesions in the 3 neurofibroma cases. In 1 case of neurofibroma, the lesion demonstrated some small areas of remnant tumor in the radiosurgical target zone. CONCLUSIONS This case series demonstrates important histopathological characteristics of spinal lesions treated by SRS. Regions with the highest exposure to radiation appear to be densely necrotic and show little evidence of tumor growth, whereas peripheral regions distant from the radiation dosage are more likely to demonstrate viable tumor in malignant and benign neoplasms. Physiological tissue appears to be similarly affected. With additional investigation, a more homogenized field of hypofractionated radiation exposure may allow for tumor obliteration with relative preservation of critical anatomical structures.

Pathological changes of the hippocampus and cognitive dysfunction following frontal lobe surgery in a rat model.

BACKGROUND: Postoperative cognitive dysfunction (POCD) is a known complication after intracranial surgery. Impaired hippocampal neurogenesis has been associated with cognitive dysfunction in animal models. METHODS: In order to assess hippocampal changes after brain surgery, a frontal lobe corticectomy was performed in ten adult Wistar rats (group 4). Three different control groups (n = 10 each) included no treatment (G1), general anesthesia alone (G2), and craniectomy without dural opening (G3). Twenty-four hours after surgery, half of the animals were killed, and the mRNA levels for IL-6, TNF-α, and brain-derived growth factor (BDNF) in the contralateral hippocampus were assessed by qPCR. Seven days later, the remaining animals underwent anxiety and memory testing. Afterwards, the number of immature neurons in the hippocampal cortex was measured by doublecortin (DCX) staining. RESULTS: Twenty-four hours after surgery, mRNA levels of IL-6 and TNF-α increased and BDNF decreased in both surgical groups G3 and G4 (p = 0.012). Cognitive tests demonstrated an increase in anxiety levels and memory impairment in surgical groups compared with non-surgical animals. These changes correlated with an inhibition of hippocampal neurogenesis evidenced by a decreased number of new neurons (mean ± SD for G1-4: 66.4 ± 24; 57.6 ± 22.2; 21.3 ± 3.78; 5.7 ± 1.05, p < 0.001, non-parametric ANOVA). CONCLUSIONS: Intracranial surgery was demonstrated to induce an inflammatory reaction within the hippocampus that compromised neurogenesis and impaired normal cognitive processing. Corticectomy had a greater effect than craniotomy alone, indicating a central trigger for hippocampal inflammatory changes. POCD after craniotomy may originate from a central inflammatory response resulting from surgical trauma to the brain parenchyma.

Plasma disc decompression compared to physiotherapy for symptomatic contained lumbar disc herniation: A prospective randomized controlled trial.

INTRODUCTION: To evaluate clinical outcomes with PDD as compared with patients who underwent to standard physiotherapy intervention. MATERIAL AND METHODS: One-hundred-seventy-seven randomly assigned patients with primarily radicular pain associated with a single-level lumbar contained disc herniation were enrolled. Participants received either PDD (89 patients) or conservative physiotherapy care (88 patients). RESULTS: Patients in the PDD group had significantly greater reduction in leg pain scores and significantly improved VAS (p<0.001), Oswestry Disability Index (p<0.05), and 36-Item Short Form, than those in the physiotherapy group at 12 months. On subset analysis, patients achieved even better outcomes after PPD who: were younger, had a shorter period of radiculopathy, of male gender, and lower BMI. Patients with subacute pain reported better outcomes than those with chronic pain in the PDD group. CONCLUSIONS: Patient selection for PDD over physiotherapy favored younger patients who presented with a shorter period of pain symptoms and who had a more favorable body habitus.

Single versus multiple session stereotactic body radiotherapy for spinal metastasis: the risk-benefit ratio.

Spine stereotactic body radiation therapy represents an important advancement in the management of spinal metastases that allows precise delivery of ablative doses of radiation therapy with excellent local control. Although the technique is being increasingly used in clinical practice, the optimal fractionation schedule remains uncertain. In this perspective paper, we review radiobiologic principles that support the use of multiple- versus single-fraction spine stereotactic body radiation therapy schedules and clinical data supporting the multiple-fraction approach. Specifically, we suggest that there may be a local control benefit of fractionation, while helping to limit the risk of toxicities such as vertebral body fracture, pain flare and radiation myelopathy. We conclude with future directions and the need for future study on this important topic.

Stereotactic radiosurgery and immunotherapy for metastatic spinal melanoma.

The management of metastatic spinal melanoma involves maximizing local control, preventing recurrence, and minimizing treatment-associated toxicity and spinal cord damage. Additionally, therapeutic measures should promote mechanical stability, facilitate rehabilitation, and promote quality of life. These objectives prove difficult to achieve given melanoma's elusive nature, radioresistant and chemoresistant histology, vascular character, and tendency for rapid and early metastasis. Different therapeutic modalities exist for metastatic spinal melanoma treatment, including resection (definitive, debulking, or stabilization procedures), stereotactic radiosurgery, and immunotherapeutic techniques, but no single treatment modality has proven fully effective. The authors present a conceptual overview and critique of these techniques, assessing their effectiveness, separately and combined, in the treatment of metastatic spinal melanoma. They provide an up-to-date guide for multidisciplinary treatment strategies. Protocols that incorporate specific, goal-defined surgery, immunotherapy, and stereotactic radiosurgery would be beneficial in efforts to maximize local control and minimize toxicity.

The history of military cranioplasty.

There is evidence that the neurosurgical procedure of cranioplasty is as ancient as its better-known counterpart, trephination. With origins in pre-Incan Peru, cranioplasty remains an important reconstructive procedure for modern craniofacial surgery teams to master. Solutions to the often challenging problem of repairing skull defects continue to evolve to improve patient outcomes. Throughout recorded history, advances in cranioplasty have paralleled major military conflicts due to survivorship after trephination or decompressive craniectomy. Primitive skull coverings used in Peru were later replaced during the Middle Ages by grafts obtained in animals and humans. Improved survivorship secondary to advances in anesthesia and battlefield medicine during the Crimean War and the American Civil War allowed the use of tantalum and acrylic cranioplasty to evolve during World Wars I and II. In the modern era of the Iraq and Afghanistan conflicts, greater survivorship after cranial injury due to improvements in protective armor, medical evacuation, and early "far-forward" neurosurgical treatment have occurred. Consequently, the last decade has seen great advancement in cranial defect reconstruction, including custom-fabricated alloplast implants and the emergence of regenerative cranial treatments such as distraction osteogenesis, protected bone regeneration, and free tissue transfers. Comprehensive rehabilitation after neurotrauma has emerged as the new standard of care.

Analysis of injected cement volume and clinical outcomes following balloon-assisted kyphoplasty in a series of 368 patients.

OBJECTIVE: Balloon-assisted kyphoplasty (BAK) is a modified vertebroplasty technique developed to treat vertebral compression fractures (VCFs) secondary to osteoporosis. This study investigates the association between injected cement volume and the development of subsequent VCFs after BAK. METHODS: A retrospective analysis of 368 patients who underwent BAK at a single institution was performed from 2001 to 2021. Inclusion was defined by at least 2 years of follow-up. Clinical characteristics and outcomes following BAK, including subsequent fractures at adjacent and remote levels, were identified. Patients that underwent a thoracic BAK were stratified by injected cement volume: below or equal to the median (≤ 6.0 mL, 265 vertebrae) or above the median (> 6.0 mL, 144 vertebrae). Patients that underwent a lumbar BAK were similarly stratified: below or equal to the median (≤ 8.0 mL, 233 vertebrae) or above the median (>8.0 mL, 160 vertebrae). RESULTS: A total of 802 vertebrae were treated. The average volume of cement was recorded in the thoracic (6.2 ± 1.9 mL) and lumbar (7.8 ± 1.8 mL) vertebrae. In the thoracic spine, vertebrae that were injected with > 6.0 mL of cement underwent a greater change in local kyphotic angle (P = 0.0001) and were more likely to develop adjacent-level VCFs (P = 0.032) after kyphoplasty. Univariate analysis did not elucidate any additional risk factors. There were no statistical differences in clinical outcomes between the three groups of lumbar vertebrae. CONCLUSIONS: Larger volumes of injected cement were associated with a greater change in local kyphosis and subsequent adjacent-level fractures after BAK in the thoracic spine. This association was not found in the lumbar spine. Close attention to injected cement volumes must be made in the thoracic spine and patients who undergo significant kyphotic correction should be carefully observed postoperatively.

Prediction of 30-day and 1-year postoperative complications after balloon-assisted kyphoplasty in the elderly using the Risk Analysis Index.

OBJECTIVE: Vertebral compression fracture (VCF) is the most prevalent fragility fracture. When conservative management fails, patients may undergo balloon-assisted kyphoplasty (BAK). In BAK, an expandable balloon preforms a cavity in the fractured vertebra before injection of bone cement. The aim of this study was to compare outcomes in patients stratified by age and frailty assessed by the Risk Analysis Index (RAI). METHODS: A retrospective analysis of 334 BAK procedures (280 patients) for osteoporotic VCFs at a single institution was performed (2015-2022). Patients with at least 1 year of follow-up were eligible for inclusion. Patient demographics were recorded, including age, sex, BMI, RAI score, tobacco and steroid use, osteoporosis treatments, and bone density. Patients who underwent outpatient surgery were identified, and length of stay (LOS) was obtained for admitted patients. The rates of additional VCFs after kyphoplasty, 30-day and 1-year postoperative complications, and reoperation were identified. RESULTS: The overall rates of additional VCFs, 30-day postoperative complications, 1-year postoperative complications, and reoperation were 16.2%, 5.1%, 12.0%, and 6.3%, respectively. Patients were stratified by age: nonelderly (< 80 years; 220 patients, 263 treated vertebrae) and elderly (≥ 80 years; 60 patients, 71 treated vertebrae). There were no differences in sex (p = 0.593), tobacco use (p = 0.973), chronic steroid use (p = 0.794), treatment for osteoporosis (p = 0.537), bone density (p = 0.056), outpatient procedure (p = 0.273), and inpatient LOS (p = 0.661) between both groups. There were also no differences in the development of additional VCFs (p = 0.862) at an adjacent level (p = 0.739) or remote level (p = 0.814), 30-day and 1-year postoperative complications (p = 0.794 and p = 0.560, respectively), and reoperation rates (p = 0.420). Patients were then analyzed by RAI: nonfrail (RAI score < 30; 203 patients, 243 treated vertebrae) and frail (RAI score ≥ 31; 77 patients, 91 treated vertebrae). There were no differences in tobacco use (p = 0.959), chronic steroid use (p = 0.658), treatment for osteoporosis (p = 0.560), bone density (p = 0.339), outpatient procedure (p = 0.241), inpatient LOS (p = 0.570), and development of additional VCFs (p = 0.773) at an adjacent level (p = 0.390) or remote level (p = 0.689). However, rates of 30-day and 1-year postoperative complications in frail patients more than doubled in comparison with nonfrail patients (p = 0.031 and p = 0.007, respectively), and frail patients trended toward reoperation (p = 0.097). CONCLUSIONS: BAK is a safe treatment in the elderly, and age alone should not be used as an exclusion criterion during patient selection. Frailty, which can be assessed reliably using the RAI, may serve as a better predictor for postoperative complications and reoperation following BAK.

Stereotactic Radiosurgery for Patients with Spinal Metastases from Thyroid Cancer: A 20-Year Experience.

OBJECTIVE: Primary thyroid cancer metastasizing to the spine portends poor survival and low quality of life. Current management strategies continue to evolve. This single-institution retrospective study analyzes outcomes after spinal stereotactic radiosurgery for patients with spinal metastases from thyroid cancer. METHODS: Nineteen patients (median age: 64.5 years) were treated with stereotactic radiosurgery (SRS) for spinal primary thyroid metastases (40 metastases, 47 vertebral levels) between 2003 and 2023. Nineteen (47.5%) lesions had epidural involvement and 20 (50%) lesions were classified as potentially unstable or unstable via the Spinal Instability Neoplastic Score. The median tumor volume per lesion was 33 cc (range: 1.5-153). The median single fraction prescription dose was 20 Gy (range: 12-23.5). RESULTS: The median follow-up period was 15 months (range: 2-40). Five (12.8%) lesions locally progressed at a median of 9 months (range: 4-26) after SRS. The 1-, 2-, and 3-year local tumor control rates per lesion were 90.4%, 83.5%, and 75.9%, respectively. On univariate analysis, age at SRS >70 years (P = 0.05, hazard ratio: 6.86, 95% confidence interval: 1.01-46.7) was significantly correlated with lower rates of local tumor control. The median overall survival was 35 months (range: 2-141). The 1-, 2-, and 3-year overall survival rates were 73.7%, 50.4%, and 43.2%, respectively. For 33 lesions initially associated with pain, patients reported pain improvement (22 lesions, 66.7%), stability (10 lesions, 30.3%), and worsening (1 lesion, 3.0%) after SRS. One patient developed dysphagia 4 months after SRS treatment. CONCLUSIONS: SRS can be utilized as an effective and safe primary and adjuvant treatment option for primary thyroid metastases to the spine.

Machine Learning in Spine Surgery: A Narrative Review.

Artificial intelligence and machine learning (ML) can offer revolutionary advances in their application to the field of spine surgery. Within the past 5 years, novel applications of ML have assisted in surgical decision-making, intraoperative imaging and navigation, and optimization of clinical outcomes. ML has the capacity to address many different clinical needs and improve diagnostic and surgical techniques. This review will discuss current applications of ML in the context of spine surgery by breaking down its implementation preoperatively, intraoperatively, and postoperatively. Ethical considerations to ML and challenges in ML implementation must be addressed to maximally benefit patients, spine surgeons, and the healthcare system. Areas for future research in augmented reality and mixed reality, along with limitations in generalizability and bias, will also be highlighted.

Usefulness and Accuracy of Artificial Intelligence Chatbot Responses to Patient Questions for Neurosurgical Procedures.

BACKGROUND AND OBJECTIVES: The Internet has become a primary source of health information, leading patients to seek answers online before consulting health care providers. This study aims to evaluate the implementation of Chat Generative Pre-Trained Transformer (ChatGPT) in neurosurgery by assessing the accuracy and helpfulness of artificial intelligence (AI)-generated responses to common postsurgical questions. METHODS: A list of 60 commonly asked questions regarding neurosurgical procedures was developed. ChatGPT-3.0, ChatGPT-3.5, and ChatGPT-4.0 responses to these questions were recorded and graded by numerous practitioners for accuracy and helpfulness. The understandability and actionability of the answers were assessed using the Patient Education Materials Assessment Tool. Readability analysis was conducted using established scales. RESULTS: A total of 1080 responses were evaluated, equally divided among ChatGPT-3.0, 3.5, and 4.0, each contributing 360 responses. The mean helpfulness score across the 3 subsections was 3.511 ± 0.647 while the accuracy score was 4.165 ± 0.567. The Patient Education Materials Assessment Tool analysis revealed that the AI-generated responses had higher actionability scores than understandability. This indicates that the answers provided practical guidance and recommendations that patients could apply effectively. On the other hand, the mean Flesch Reading Ease score was 33.5, suggesting that the readability level of the responses was relatively complex. The Raygor Readability Estimate scores ranged within the graduate level, with an average score of the 15th grade. CONCLUSION: The artificial intelligence chatbot's responses, although factually accurate, were not rated highly beneficial, with only marginal differences in perceived helpfulness and accuracy between ChatGPT-3.0 and ChatGPT-3.5 versions. Despite this, the responses from ChatGPT-4.0 showed a notable improvement in understandability, indicating enhanced readability over earlier versions.

Neural population dynamics reveals disruption of spinal circuits' responses to proprioceptive input during electrical stimulation of sensory afferents.

While neurostimulation technologies are rapidly approaching clinical applications for sensorimotor disorders, the impact of electrical stimulation on network dynamics is still unknown. Given the high degree of shared processing in neural structures, it is critical to understand if neurostimulation affects functions that are related to, but not targeted by, the intervention. Here, we approach this question by studying the effects of electrical stimulation of cutaneous afferents on unrelated processing of proprioceptive inputs. We recorded intraspinal neural activity in four monkeys while generating proprioceptive inputs from the radial nerve. We then applied continuous stimulation to the radial nerve cutaneous branch and quantified the impact of the stimulation on spinal processing of proprioceptive inputs via neural population dynamics. Proprioceptive pulses consistently produce neural trajectories that are disrupted by concurrent cutaneous stimulation. This disruption propagates to the somatosensory cortex, suggesting that electrical stimulation can perturb natural information processing across the neural axis.