Brain Tumor Surgery Research Articles

Spectral library and method for sparse unmixing of hyperspectral images in fluorescence guided resection of brain tumors.

Through spectral unmixing, hyperspectral imaging (HSI) in fluorescence-guided brain tumor surgery has enabled the detection and classification of tumor regions invisible to the human eye. Prior unmixing work has focused on determining a minimal set of viable fluorophore spectra known to be present in the brain and effectively reconstructing human data without overfitting. With these endmembers, non-negative least squares regression (NNLS) was commonly used to compute the abundances. However, HSI images are heterogeneous, so one small set of endmember spectra may not fit all pixels well. Additionally, NNLS is the maximum likelihood estimator only if the measurement is normally distributed, and it does not enforce sparsity, which leads to overfitting and unphysical results. In this paper, we analyzed 555666 HSI fluorescence spectra from 891 ex vivo measurements of patients with various brain tumors to show that a Poisson distribution indeed models the measured data 82% better than a Gaussian in terms of the Kullback-Leibler divergence, and that the endmember abundance vectors are sparse. With this knowledge, we introduce (1) a library of 9 endmember spectra, including PpIX (620 nm and 634 nm photostates), NADH, FAD, flavins, lipofuscin, melanin, elastin, and collagen, (2) a sparse, non-negative Poisson regression algorithm to perform physics-informed unmixing with this library without overfitting, and (3) a highly realistic spectral measurement simulation with known endmember abundances. The new unmixing method was then tested on the human and simulated data and compared to four other candidate methods. It outperforms previous methods with 25% lower error in the computed abundances on the simulated data than NNLS, lower reconstruction error on human data, better sparsity, and 31 times faster runtime than state-of-the-art Poisson regression. This method and library of endmember spectra can enable more accurate spectral unmixing to aid the surgeon better during brain tumor resection.

Thiopental-Dexmedetomidine as Adjuvant Anesthesia for Craniotomy Tumor Removal: A Case Report

Brain tumor surgery requires special anesthesia to get a slack brain and perform perioperative brain protection. The selected anesthetic drugs and adjuvants have the ability of anesthesia sparring effect and have a brain protective effect. Not many have done the combination of thiopental adjuvant with dexmedetomidine. The purpose of this case report is to see the effect of the combination of thiopental with dexmedetomidine as an adjuvant anesthesia on hemodynamics and slack brain and successful removal of brain tumors. A woman, 32 years old, with meningiomas had surgery to remove a brain tumor at Santosa Bandung Central Hospital. Preoperative examination showed blood lab results within normal limits, the presence of large meningioma and midline shift. Induction of anesthesia with thiopental 5 mg/kgBW, rocuronium bromide 0.9 mg/kgBW, fentanyl 3 mcg/kg and anesthetic maintenance with sevoflurane below 1.5 MAC, oxygen/air, continuous rocuronium 0.5 mg/kgBW/hour, thiopental and continuous dexmedetomidine. The anesthetic adjuvant used was thiopental 1-3 mg/kg/hour and continuous dexmedetomidine 0.4–0.7 mcg/kg/hour. A slack brain is obtained, and 90% of the tumor could be removed, and transfused during surgery 4 units pack red cells (PRC), crystalloid liquid as much as 2,500 cc, and colloidal fluid as much as 2,000 cc. The length of surgery is 11 hours. Post-surgery was treated in the ICU for 5 days, then moved to the ward for 2 days then the patient could be discharged from the hospital. The use of thiopental and dexmedetomidine continuously can produce slack brain and almost the entire tumor can be removed.

QOL-35. ANALYSIS ON THE EVOLUTIONARY PATTERN OF COGNITIVE FUNCTIONS IN CHILDREN ON FOLLOW-UP FOR BRAIN TUMORS

Abstract BACKGROUND Long-term cognitive sequelae of paediatric brain tumors are of increasing interest. The role of histology and surgery remains still unclear. Our study aimed to evaluate children cognitive functioning before and after brain tumors surgery, and at the end of additional treatments. METHODS New diagnoses of paediatric primary brain tumors were prospectively assessed. Neurocognitive evaluations were performed at diagnosis (T0), within 7-10 days from surgery (T1) and 12-18 months after the end of treatments (T2). Language, learning and memory, attention, executive functions, visuo-constructional and sensorimotor skills were evaluated at T0 and T1, Intelligent Quotient (IQ) was explored at T0 and T2. RESULTS Twenty-five patients (M:F=15:10, mean age 10.9±3.4 years) were enrolled between January 2019 and December 2022. In comparison to normal values (>7.0), at baseline patients showed major deficits in narrative memory (6.6±3.7, p<0.001) and visuo-spatial memory (copy design tasks: general 6.8±3.9, p<0.001, specific 6.2±3.3, p<0.001, motor 5.2±3.2, p<0.001). At T1 assessment, significant deficits remained in narrative memory (6.2±3.3, p<0.001) and visual-motor coordination (copy design tasks: specific 5.9±3.0, p<0.001 and motor 4.8±4.3 p<0.001); attention and visual-constructional abilities significantly improved (p=0.04 and p=0.001). On the visual construction test, children with high-grade histology scored lower than the low-grade group (Rey- Osterrieth complex figure-copy 5.1±4.4 vs 11.0±4.3; p=0.019). At T2 evaluation children showed persistent deficits in visuo-spatial processing and a possible decline in IQ scores, with lower scores compared with T0 (93 vs 100, p=0.05). CONCLUSIONS Children with brain tumors may present several neuropsychological impairments at diagnosis, particularly those with high-grade diseases. Surgery may have a positive effect on the recovery of some cognitive functions. However, cognitive decline may worsen over time. Baseline and periodic neurocognitive evaluations should be encouraged to identify functional difficulties and to develop a tailored treatment approach for the patient.

BIOM-01. CARBONIC ANHYDRASE IX INTERPLAY WITH LOCAL AND SYSTEMIC IMMUNE RESPONSE IN PEDIATRIC BRAIN TUMORS

Abstract BACKGROUND Brain tumors (BT) remain the leading cause of death among childhood cancers. There is an urgent need to identify novel targets in these patients. BT progression depends on the adaptive responses to hypoxia. Carbonic anhydrase IX (CAIX) helps cancer cells survive in a hypoxic environment and can be potentially as a therapeutic target. The role of CAIX in the interplay between the tumor and immune cells requires in-depth investigation to design effective therapies. METHODS Fresh BT, blood, and intraoperative cerebrospinal fluid (iCSF) samples were collected prospectively from pediatric patients, who underwent brain tumor surgery at Vilnius University Hospital Santaros Klinikos from March 2022 to December 2023. All tumor types were included. Immunohistochemistry (IHC) and flow cytometry (FC) were performed to analyze the expression of CAIX and selected immunological markers in the fresh tumor, iCSF and peripheral blood mononuclear cells (PBMCs). Soluble CAIX content in serum and iCSF was assessed by ELISA. In addition, a retrospective analysis of previously diagnosed pediatric glioma specimens was performed by IHC. RESULTS Twelve patients with heterogeneous BT types have been enrolled prospectively and 17 patients with glioma were reviewed retrospectively. Glioma accounted for 72% (21/29) of all samples. IHC showed that 57% of gliomas were positive for CAIX as well as a moderate correlation between the CAIX score and the expression of CD44, CD206, and CCR2 markers. PD-1/PD-L1 expression was negligible. In the prospective cohort, 83% (10/12) of BT tissue was positive for CAIX by IHC and FC. Soluble CAIX was detectable in 40% of iCSF samples, but not in serum. We found a correlation trend of CAIX expression in the fresh tumor cells and iCSF with increased CCR2 expression on CD45+ PBMCs. CONCLUSIONS This interim analysis showed a correlation between CAIX tumor expression and immune biomarkers, prompting further investigation by enrolling more patients.

Clinical application of intraoperative ultrasound superb microvascular imaging in brain tumors resections: contributing to the achievement of total tumoral resection

BackgroundTo investigate whether the intraoperative superb microvascular imaging(SMI) technique helps evaluate lesion boundaries compared with conventional grayscale ultrasound in brain tumor surgery and to explore factors that may be associated with complete radiographic resection.MethodsThis study enrolled 57 consecutive brain tumor patients undergoing surgery. During the operation, B-mode and SMI ultrasound evaluated the boundaries of brain tumors. MRI before and within 48h after surgery was used as the gold standard to evaluate gross-total resection(GTR). The ultrasound findings and GTR results were analyzed to determine the imaging factors related to GTR.ResultsA total of 57 patients were enrolled in the study, including 32 males and 25 females, with an average age of 53.4 ± 14.1 years old(range 19 ~ 80). According to the assessment criteria of MRI, before and within 48 h after the operation, 37(63.9%) cases were classified as GTR, and 20(35.1%) cases were classified as GTR. In comparing tumor interface definition between B-mode and SMI mode, SMI improved HGG boundary recognition in 5 cases(P = 0.033). The results showed that the tumor size ≥ 5 cm and unclear ultrasonic boundary were independent risk factors for nGTR (OR>1, P<0.05).ConclusionsAs an innovative intraoperative doppler technique in neurosurgery, SMI can effectively demarcate the tumor’s boundary and help achieve GTR as much as possible.

Adrenal Insufficiency Presenting as Pulseless Ventricular Tachycardia

Adrenal insufficiency (AI) is a severe sickness induced by adrenal gland or hypothalamic-pituitary-adrenal (HPA) axis dysfunction. It can induce a variety of symptoms, the most serious of which are potentially fatal adrenal crises. This case report describes a clinical scenario involving a 42-year-old male patient who had previously had brain tumor surgery. The patient had presented with fever and gastrointestinal symptoms. He developed pulseless ventricular tachycardia on day two of admission. Patient was promptly treated with electrical cardioversion. Workup revealed QT prolongation on ECG and adrenal insufficiency. Both the patient’s arrhythmias and QT prolongation on ECG responded to intravenous hydrocortisone.

In situ brain tumor detection using a Raman spectroscopy system—results of a multicenter study

Safe and effective brain tumor surgery aims to remove tumor tissue, not non-tumoral brain. This is a challenge since tumor cells are often not visually distinguishable from peritumoral brain during surgery. To address this, we conducted a multicenter study testing whether the Sentry System could distinguish the three most common types of brain tumors from brain tissue in a label-free manner. The Sentry System is a new real time, in situ brain tumor detection device that merges Raman spectroscopy with machine learning tissue classifiers. Nine hundred and seventy-six in situ spectroscopy measurements and colocalized tissue specimens were acquired from 67 patients undergoing surgery for glioblastoma, brain metastases, or meningioma to assess tumor classification. The device achieved diagnostic accuracies of 91% for glioblastoma, 97% for brain metastases, and 96% for meningiomas. These data show that the Sentry System discriminated tumor containing tissue from non-tumoral brain in real time and prior to resection.

Intraoperative Ultrasound: An Old but Ever New Technology for a More Personalized Approach to Brain Tumor Surgery.

Although the use of transcranial ultrasound dates to the mid-20th century, the main purpose of this research work is to standardize its use in the resection of brain tumors. This is due to its wide availability, low cost, lack of contraindications, and absence of harmful effects for the patient and medical staff, along with the possibility of real-time verification of the complete resection of tumor lesions and minimization of vascular injuries or damage to adjacent structures. A retrospective study was conducted from June to December 2022. The study included eight patients (three men and five women) aged between 32 and 76 years. Histological examination revealed two high-grade gliomas, one low-grade glioma, and five metastatic lesions. The low-grade glioma appeared as a homogeneously echogenic structure and easily distinguishable from brain parenchyma, whereas metastases and high-grade gliomas showed higher echogenicity, being identified as malignant lesions due to areas of low echogenicity necrosis and peritumoral edema identified as a hyperechogenic structure. The use of intraoperative transcranial ultrasound constitutes an important tool for neurosurgeons during tumor resection. Although it is easy to use, intraoperative ultrasound requires a relatively short learning curve and a good understanding of the fundamentals of ultrasound. Its main advantage over neuronavigation is that it is not affected by the "brain shift" phenomenon that commonly occurs during tumor resection, since the ultrasound images are updated during surgery.

Brain tumor surgery guided by navigated transcranial magnetic stimulation mapping for arithmetic calculation.

The onco-functional balance represents the primary goal in neuro-oncology. The increasing use of navigated transcranial magnetic stimulation (nTMS) allows the noninvasive characterization of cortical functional anatomy, and its reliability for motor and language mapping has previously been validated. Calculation and arithmetic processing has not been studied with nTMS so far. In this study, the authors present their preliminary data concerning nTMS calculation. The authors designed a monocentric prospective study, adopting an internal protocol to use nTMS for preoperative planning, including arithmetic processing. When awake surgery was possible, according to the patients' conditions, nTMS points were used to guide direct cortical stimulation (DCS), i.e., the gold standard for cortical mapping. Navigated TMS-based tractography was used for surgical planning. Statistical analyses on the nTMS and DCS points were performed. From February 2021 to October 2023, 61 procedures for nTMS calculation mapping were performed. The clinical evaluation, including pre- and postoperative evaluations (3 months after surgery), demonstrated a good clinical outcome with preservation of arithmetic function and recovery (92.8% of patients). Between the awake and asleep surgery groups, the postoperative clinical results were comparable at the 3-month follow-up, with > 90% of the patients achieving improved calculation function. The surgical strategy adopted was aimed at sparing nTMS positive points in asleep procedures, whereas nTMS and DCS positive points were not removed in awake procedures. Overall, 62% of the positive points for calculation functions were exposed by craniotomy and 85% were spared during surgery. None of the patients developed nTMS-related seizures. Diffusion tensor imaging fiber tracking based on nTMS positive points for calculation was used. The white matter fiber tracts involved in calculation functions were the arcuate fasciculus (56%) and frontal aslant tract (22%). When nTMS and DCS points were compared in awake surgery (n = 10 patients), a sensitivity of 31.71%, specificity of 85.76%, positive predictive value of 22.41%, negative predictive value of 90.64%, and accuracy of approximately 69% were achieved. Based on the authors' preliminary data, nTMS can be an advantageous tool to study cognitive functions, aimed at minimizing neurological impairment. The postoperative clinical outcome for patients who underwent operation with nTMS was very good. Considering these results, nTMS has proved to be a feasible method to map cognitive areas including those for calculation functions. Further analyses are needed to validate these data. Finally, other cognitive functions (e.g., visuospatial) may be explored with nTMS.

The Relationship Between Kinesiophobia and Mobilization of Patients with Brain Tumor Surgery

The Relationship Between Kinesiophobia and Mobilization of Patients with Brain Tumor Surgery

Surgical treatment of pediatric low-grade glioma in developing countries.

Pediatric low-grade gliomas constitute the most common brain tumors worldwide, though with some peculiarities in the presentation and surgical care in different parts of the world. The symptomatology in developing countries is likely to be over longer periods with a tendency to delayed diagnosis due to cultural, religious beliefs, manpower, and infrastructural deficits. Thus, the children present with large tumors with attendant morbidities and an increased risk of mortalities from surgery. Surgery is mainly by "general" neurosurgeons due to the paucity of trained pediatric neurosurgeons. The pre-operative imaging may be limited to anatomic MR imaging, and in some cases, CT scans, without expansive neuropsychological evaluation. The armamentarium available to the neurosurgeon may warrant large openings to access the tumor, and there may be limited possibility for intra-operative mapping of "eloquent" brain functions when this is deemed necessary. Complicating pre-operative acute hydrocephalus can result in two operations that further worsen the catastrophic spending associated with brain tumor surgeries in these climes. While these challenges appear daunting but certainly have not been enough to deter the "can do" spirit of neurosurgeons in developing countries, it is essential to strengthen the training of pediatric neurosurgeons in LMICs and provide a platform for the advocacy of better infrastructure for the surgical management of these tumors.

Optical Methods for Brain Tumor Detection: A Systematic Review.

Background: In brain tumor surgery, maximal tumor resection is typically desired. This is complicated by infiltrative tumor cells which cannot be visually distinguished from healthy brain tissue. Optical methods are an emerging field that can potentially revolutionize brain tumor surgery through intraoperative differentiation between healthy and tumor tissues. Methods: This study aimed to systematically explore and summarize the existing literature on the use of Raman Spectroscopy (RS), Hyperspectral Imaging (HSI), Optical Coherence Tomography (OCT), and Diffuse Reflectance Spectroscopy (DRS) for brain tumor detection. MEDLINE, Embase, and Web of Science were searched for studies evaluating the accuracy of these systems for brain tumor detection. Outcome measures included accuracy, sensitivity, and specificity. Results: In total, 44 studies were included, covering a range of tumor types and technologies. Accuracy metrics in the studies ranged between 54 and 100% for RS, 69 and 99% for HSI, 82 and 99% for OCT, and 42 and 100% for DRS. Conclusions: This review provides insightful evidence on the use of optical methods in distinguishing tumor from healthy brain tissue.

Systematic Review Between Resting-State fMRI and Task fMRI in Planning for Brain Tumour Surgery.

As an alternative to task-based functional magnetic resonance imaging (T-fMRI), resting-state functional magnetic resonance imaging (Rs-fMRI) is suggested for preoperative mapping of patients with brain tumours, with an emphasis on treatment guidance and neurodegeneration prediction. A systematic review was conducted of 18 recent studies involving 1035 patients with brain tumours and Rs-fMRI protocols. This was accomplished by searching the electronic databases PubMed, Scopus, and Web of Science. For clinical benefit, we compared Rs-fMRI to standard T-fMRI and intraoperative direct cortical stimulation (DCS). The results of Rs-fMRI and T-fMRI were compared and their correlation with intraoperative DCS results was examined through a systematic review. Our exhaustive investigation demonstrated that Rs-fMRI is a dependable and sensitive preoperative mapping technique that detects neural networks in the brain with precision and identifies crucial functional regions in agreement with intraoperative DCS. Rs-fMRI comes in handy, especially in situations where T-fMRI proves to be difficult because of patient-specific factors. Additionally, our exhaustive investigation demonstrated that Rs-fMRI is a valuable tool in the preoperative screening and evaluation of brain tumours. Furthermore, its capability to assess brain function, forecast surgical results, and enhance decision-making may render it applicable in the clinical management of brain tumours.

Aspirin interruption before neurosurgical interventions: A controversial problem.

Aspirin is widely used for primary or secondary prevention of ischemic events. At the same time, chronic aspirin consumption can affect blood clot formation during surgical intervention and increase intraoperative blood loss. This is especially important for high-risk surgery, including neurosurgery. Current European Society of Cardiology guidelines recommend aspirin interruption for at least 7 d before neurosurgical intervention, but this suggestion is not supported by clinical evidence. This narrative review presents evidence that challenges the necessity for aspirin interruption in neurosurgical patients, describes options for aspirin effect monitoring and the clinical implication of these methods, and summarizes current clinical data on bleeding risk associated with chronic aspirin therapy in neurosurgical patients, including brain tumor surgery, cerebrovascular procedures, and spinal surgery.

Intraoperative radiotherapy combined with spinal stabilization surgery—a novel treatment strategy for spinal metastases based on a first single-center experiences

IntroductionCurrent treatment of spinal metastases (SM) aims on preserving spinal stability, neurological status, and functional status as well as achieving local control. It consists of spinal surgery followed by radiotherapy and/or systemic treatment. Adjuvant therapy usually starts with a delay of a few weeks to prevent wound healing issues. Intraoperative radiotherapy (IORT) has previously been successfully applied during brain tumor, breast and colorectal carcinoma surgery but not in SM, including unstable one, to date. In our case series, we describe the feasibility, morbidity and mortality of a novel treatment protocol for SM combining stabilization surgery with IORT.MethodsSingle center case series on patients with SM. Single session stabilization by navigated open or percutaneous procedure using a carbon screw-rod system followed by concurrent 50 kV photon-IORT (ZEISS Intrabeam). The IORT probe is placed via a guide canula using navigation, positioning is controlled by IOCT or 3D-fluroscopy enabling RT isodose planning in the OR.Results15 (8 female) patients (71 ± 10y) received this treatment between 07/22 and 09/23. Median Spinal Neoplastic Instability Score was 8 [7–10] IQR. Most metastasis were located in the thoracic (n = 11, 73.3%) and the rest in the lumbar (n = 4, 26.7%) spine. 9 (60%) patients received open, 5 (33%) percutaneous stabilization and 1 (7%) decompression only. Mean length of surgery was 157 ± 45 min. Eleven patients had 8 and 3 had 4 screws placed. In 2 patients radiotherapy was not completed due to bending of the guide canula with consecutive abortion of IORT. All other patients received 8 Gy isodoses at mdn. 1.5 cm [1.1–1.9, IQR] depth during 2-6 min. The patients had Epidural Spinal Cord Compression score 1a-3. Seven patients (46.7%) experienced adverse events including 2 surgical site infection (one 65 days after surgery).Conclusion50 kV photon IORT for SM and consecutive unstable spine needing surgical intervention is safe and feasible and can be a promising technique in selected cases.

Effects of dependent care theory-based post-surgical home care intervention on self-care, symptoms, and caregiver burden in patients with primary brain tumor and their caregivers: a randomized controlled trial

PurposeThis study aimed to examine the effect of dependent care theory-based post-surgical home care intervention on self-care, symptoms, and caregiver burden in primary brain tumor patients and their caregivers.MethodsA parallel-group randomized controlled trial was conducted with patients who underwent surgery for a primary brain tumor between March 2019 and January 2020 in a tertiary hospital and with caregivers who cared for them at home. Eligible patients and caregivers were determined by block randomization. Outcome measures included validated measures of self-care agency (Self-Care Agency Scale), symptoms and interference by symptoms (MD Anderson Symptom Inventory Brain Tumor-Turkish Form), and caregiver burden (Caregiver Burden Scale). Two-way analysis of variance was used in repeated measurements from general linear models compared to scale scores.ResultsSelf-care agency was significantly higher in the intervention group than in the control group in the first and sixth months after surgery (p < 0.05). The severity of the patients’ emotional, focal neurologic, and cognitive symptoms and interference by symptoms were significantly lower in the intervention group than in the control group (p < 0.05). Caregiver burden was significantly lower in the intervention group in the first, third, and sixth months after surgery (p < 0.05).ConclusionDependent care theory-based post-surgical home care intervention increased patients’ self-care and reduced symptoms and their effects. It also reduced the caregiver burden. Dependent care theory can guide the nursing practices of nurses who provide institutional and/or home care services to patients with chronic diseases and their caregivers.Trial RegistrationNCT05328739 on April 14, 2022 (retrospectively registered).

Nutritional status and clinical outcomes of brain tumor surgery in pediatric intensive care unit: A prospective cohort study

To determine whether nutritional status affects mortality and length of stay in the pediatric intensive care unit (PICU) after brain tumor surgery. Subjects aged 2 months to 13 years with brain tumor surgery were included in the study. Z-scores of BMI for age, weight for age, and weight for length were calculated at admission. Undernutrition was defined as Z-score<-2. Nutritional intake was measured daily by a clinical nutritionist. Outcomes to be measured included duration of hospitalization and mortality. Regression analyses was used to investigate the relationship between nutritional variables and outcomes. A total of 63 patients met the inclusion criteria. Undernutrition at admission was found in 33% of subjects based on Z-scores of BMI and weight for length. The mortality rate was 17.5%. Calorie and protein intake was <50% of the target in 50.7% and 42.8 % of children, respectively. Undernutrition by weight for age Z-score, BMI for age and weight for length Z-scores, and low protein intake increased mortality risk by 5, 5.9 and 4.7 times, respectively. The risk of shorter PICU-free days was independently 80% and 90% lower in those receiving <50% of protein and calorie requirements. Undernutrition at admission is prevalent in children undergoing brain tumor surgery and is associated with a higher risk of mortality. Caloric and protein intake during hospitalization is generally low, leading to longer PICU stay.

Evaluation of the extent of resection of intracranial tumors with virtual intraoperative MRI: a case series.

Intraoperative MRI (iMRI) is the gold-standard technique for intraoperative evaluation of the extent of resection in brain tumor surgery. Unfortunately, it is currently available at only a few neurosurgical centers. A commercially available software, Virtual iMRI Cranial, provides an elastic fusion between preoperative MRI and intraoperative CT (iCT). The aim of this study was to evaluate the accuracy of this software in determining the presence of residual tumor. Virtual iMRI was performed in patients who underwent iCT after intracranial tumor resection. The results of the software in terms of presence or absence of tumor residual were then compared with postoperative MRI performed within 48 hours after surgery to evaluate the diagnostic accuracy of virtual iMRI. Sixty-six patients were included in the present study. The virtual iMRI findings were concordant with the postoperative MRI data in 35 cases (53%) in the detection of tumor residual (p = 0.006). No false-negative findings (i.e., presence of residual on postoperative MRI and absence of residual on virtual iMRI) were encountered. Virtual iMRI had a sensitivity of 1 (95% CI 0.86-1), specificity of 0.26 (95% CI 0.14-0.42), positive predictive value of 0.44 (95% CI 0.3-0.58), and negative predictive value of 1 (95% CI 0.72-1). Subgroup analysis revealed that the virtual iMRI findings were concordant with postoperative MRI findings in all cases (n = 9) of lower-grade glioma (LGG) with a sensitivity of 1 (95% CI 0.59-1) and a specificity of 1 (95% CI 0.16-1) (p = 0.003); a statistically significant association was also found for grade 4 gliomas with a sensitivity of 1 (95% CI 0.69-1) and a specificity of 0.33 (95% CI 0.08-0.7) (p = 0.046) (19 patients). No significant association was found when considering meningiomas or metastases. The commercially available virtual iMRI can predict the presence or absence of tumor residual with high sensitivity. The diagnostic accuracy of this method was higher in LGGs and much lower for meningiomas or metastases; these findings must be evaluated in prospective studies in a larger population.

118 Intraoperative Radiotherapy Combined With Spinal Stabilization Surgery. A Novel Treatment Strategy for Spinal Metastases. First Experiences at a Single Center

INTRODUCTION: Contemporary treatment of spinal metastases (SM) aims on preserving spinal stability, neurological status, local control and functional status. It consists of spinal surgery followed by radio- and chemotherapy. Adjuvant therapy is performed after several weeks to prevent wound healing issues. Intraoperative radiotherapy (ioRT) is a solution to shorten treatment time, successfully applied in brain tumor, breast and colorectal surgery but not SM to date. METHODS: Results on morbidity and mortality of ioRT combined with stabilization surgery in SM in a first single center series are described. Stabilization is performed as CT-navigated open or percutaneous procedure using a carbon screw-rod system followed by 50kV photon-ioRT using the ZEISS Intrabeam during a single session in prone position. The ioRT probe is placed through a guide canula via navigation and positioning is controlled by ioCT to enable RT isodose planning in the OR. Patient characteristics, perioperative specifications and postoperative follow up along with adverse events (AE) are reported. RESULTS: 11 (7 female) patients (69 ± 9.4y) received treatment from 07/22-04/23. Median SINS was 8 [7-10] IQR, with metastasis located in thoracic (n = 9) and lumbar (n = 2) spine. 6 patients receive open, 4 percutaneous stabilization and 1 decompression only. Mean length of surgery was 153±52 min. with 2 Patients receiving 4 and 8 patients receiving 8 screws respectively. In 2 Patients radiotherapy was not completed due to bending of the guide canula with consecutive security abortion of ioRT. All other patients received 8Gy isodoses during 2-6 min. Patients treated had ESCC 1a-2. Mean follow up was 63 ± 49 days. 4 patients experienced AEs including 1 case of fatal surgical site infection. CONCLUSIONS: 50 kV photon ioRT for SM can be a promising technique for selected cases of SM.

491 Scalp Incisions With Stairstep Pericranial Edges to Minimize Sequalae of Poor Wound Healing in Supratentorial Brain Tumor Surgery

INTRODUCTION: Wound healing problems are especially prevalent in craniotomies for intra-axial brain tumors as patients often require radiation, chemotherapy, and chronic steroids. All surgeons have postoperative patients with poor skin healing (i.e., excessive scabbing) at follow up, some of whom progress to infections that may involve the bone graft or hardware. While newer techniques like minimally invasive approaches and routine vancomycin powder use have helped overall complication rates, poor skin healing remains a frustratingly persistent cause of morbidity. METHODS: Ninety-one consecutive patients underwent supratentorial, intra-axial brain tumor surgery with a single surgeon at a single institution using this technique. Patient demographics, pathology, adjuvant interventions, and other independent risk factors were analyzed. RESULTS: No wound-related complications requiring readmission, intravenous antibiotics, or reoperation were encountered at a median 3-month follow up. There were also no surgical site infections, dehiscences, or CSF leaks. Fifty-one patients (57.3%) had postoperative radiotherapy, eighty-five patients (93.4%) had perioperative steroids, and fifty-six patients (61.5%) had postoperative chemotherapy. Six patients (6.5%) had concerns for poor initial scalp healing at routine follow up and were placed on a short course of oral antibiotics prophylactically. None (0%) of these individuals progressed to infection or required further intervention. One other patient developed a shunt infection in this interval that required removal unrelated to the craniotomy site. CONCLUSIONS: Here we outline the principles and demonstrate the execution of stairstep pericranial edges in supratentorial brain surgery. This technique, designed with plastic surgeons, provides an intact, vascularized layer of pericranium beneath the incision and over the bone graft/hardware to optimize wound healing and prevent morbid sequelae in inevitable cases of poor initial skin healing.