Surgical Resection Of Brain Tumors Research Articles

Can we improve electrocorticography using a circular grid array in brain tumor surgery?

Intraoperative electrocorticography (iECoG) is used as an adjunct to localize the epileptogenic zone during surgical resection of brain tumors in patients with focal epilepsies. It also enables monitoring of after-discharges and seizures with EEG during functional brain mapping with electrical stimulation. When seizures or after-discharges are present, they complicate accurate interpretation of the mapping strategy to outline the brain’s eloquent function and can affect the surgical procedure. Recurrent seizures during surgery requires urgent treatment and, when occurring during awake craniotomy, often leads to premature termination of brain mapping due to post-ictal confusion or sedation from acute rescue therapy. There are mixed results in studies on efficacy with iECoG in patients with epilepsy and brain tumors influencing survival and functional outcomes following surgery. Commercially available electrode arrays have inherent limitations. These could be improved with customization potentially leading to greater precision in safe and maximal resection of brain tumors. Few studies have assessed customized electrode grid designs as an alternative to commercially available products. Higher density electrode grids with intercontact distances less than 1 cm improve spatial delineation of electrophysiologic sources, including epileptiform activity, electrographic seizures, and afterdischarges on iECoG during functional brain mapping. In response to the shortcomings of current iECoG grid technologies, we designed and developed a novel higher-density hollow circular electrode grid array. The 360-degree iECoG monitoring capability allows continuous EEG recording during surgical intervention through the aperture with and without electrical stimulation mapping. Compared with linear strip electrodes that are commonly used for iECoG during surgery, the circular grid demonstrates significant benefits in brain tumor surgery. This includes quicker recovery of post-operative motor deficits (2.4 days versus 9 days, p = 0.05), more extensive tumor resection (92.0% versus 77.6%, p = 0.003), lesser reduction in Karnofsky Performance scale postoperatively (−2 versus −11.6, p = 0.007), and more sensitivity to recording afterdischarges. In this narrative review, we discuss the advantages and disadvantages of commercially available recording devices in the operating room and focus on the usefulness of the higher-density circular grid.

Current State of Functional MRI in the Presurgical Planning of Brain Tumors.

Surgical resection of brain tumors is challenging because of the delicate balance between maximizing tumor removal and preserving vital brain functions. Functional MRI (fMRI) offers noninvasive preoperative mapping of widely distributed brain areas and is increasingly used in presurgical functional mapping. However, its impact on survival and functional outcomes is still not well-supported by evidence. Task-based fMRI (tb-fMRI) maps blood oxygen level-dependent (BOLD) signal changes during specific tasks, while resting-state fMRI (rs-fMRI) examines spontaneous brain activity. rs-fMRI may be useful for patients who cannot perform tasks, but its reliability is affected by tumor-induced changes, challenges in data processing, and noise. Validation studies comparing fMRI with direct cortical stimulation (DCS) show variable concordance, particularly for cognitive functions such as language; however, concordance for tb-fMRI is generally greater than that for rs-fMRI. Preoperative fMRI, in combination with MRI tractography and intraoperative DCS, may result in improved survival and extent of resection and reduced functional deficits. fMRI has the potential to guide surgical planning and help identify targets for intraoperative mapping, but there is currently limited prospective evidence of its impact on patient outcomes. This review describes the current state of fMRI for preoperative assessment in patients undergoing brain tumor resection. Keywords: MR-Functional Imaging, CNS, Brain/Brain Stem, Anatomy, Oncology, Functional MRI, Functional Anatomy, Task-based, Resting State, Surgical Planning, Brain Tumor © RSNA, 2023.

Tumor-related epilepsy and post-surgical outcomes: tertiary hospital experience in Vietnam

Seizures have a significant impact on the quality of life of those who suffer. This study aimed to evaluate the variables that influence the incidence of seizures during the perioperative period and effective measures to enhance epilepsy outcomes among individuals undergoing surgical resection of brain tumors. The authors carried out a prospective observational analysis of all patients who experienced seizures before their brain tumor surgery at UMC, HCMC between 2020 and 2022. 54 cases presented with seizures were enrolled for the study, generalized seizure was the most prevalent seizure type (61.1%), followed by focal seizure (29.6%). The majority of patients presented with seizures are those who were diagnosed with glioma. Low-grade gliomas and frontotemporal lobe tumors increase the postoperative risk of seizure. Other predictive factors are a prolonged history of seizure, especially resistant epilepsy and major peritumoral edema. In contrast, gross total resection reduces postoperative seizure incidence. There was correlation between Ki67 proliferation index and seizure incidence in both low-grade and high-grade gliomas. ECoG made insubstantial difference in enhancing the epilepsy surgery outcome. Overall, 88.9% of patients were seizure-free at 6 months of follow-up (Engel Class I), 7.4% were almost seizure-free (Class II), and 3.7% had significant improvement (Class III), figures for 12-month follow-up were 87.0%, 9.3%, and 3.7% respectively. A shorter history of seizure and gross-total resection appear to be associated with a favorable prognosis for seizure control.

Changes in Distributed Motor Network Connectivity Correlates With Functional Outcome After Surgical Resection of Brain Tumors

BACKGROUND: In patients with brain tumors around the motor cortices, deterioration of motor performance may be observed even if the integrity of the cortical output is maintained. Especially, resection of medial premotor area (PM) can cause postoperative deterioration called supplementary motor area syndrome. OBJECTIVE: To clarify the neuronal mechanisms underlying postsurgical deterioration with a case-control study. METHODS: Twelve patients with brain tumors underwent preoperative and postoperative sessions consisting of motor performance evaluation and 3T-magnetic resonance imaging data acquisition. Based on additional postsurgical motor deficits, 6 patients were classified into “deficit group,” and 6 others were into “no deficit group.” Using resting-state functional magnetic resonance imaging (fMRI), the integrity of functional connectivity was evaluated by placing a seed in the ipsilesional primary motor area (M1). With motor task fMRI, hand and foot representations were identified in the M1 and lateral and medial PMs. Probabilistic tractography assessed anatomic connectivity in the cortico-cortical and corticofugal networks. RESULTS: Functional connectivity among M1 and lateral and medial PMs during resting-state fMRI was reduced postoperatively in the deficit group (P < .05, corrected) and preserved in the no deficit group. The deficit was unlikely to be attributable to surgical resection of specific anatomic connectivity. The amplitude of motor-evoked potential was maintained in available cases. These intraoperative observations agree with imaging findings suggesting preserved anatomic connectivity of the estimated corticofugal pathway. CONCLUSION: The present findings suggest that supplementary motor area syndrome is caused by disorganization of functional connectivity among cortical motor networks rather than resection of anatomic connectivity of corticofugal pathway.

Duration of Prophylactic Levetiracetam After Surgery for Brain Tumor: A Prospective Randomized Trial.

Levetiracetam is commonly used as a prophylactic antiseizure medication in patients undergoing surgical resection of brain tumors. To quantitate side effects experienced in patients treated with 1 week vs 6 weeks of prophylactic levetiracetam using validated measures for neurotoxicity and depression. Patients undergoing surgical resection of a supratentorial tumor with no seizure history were randomized within 48 hours of surgery to receive prophylactic levetiracetam for the duration of either 1 or 6 weeks. Patients were given oral levetiracetam extended release 1000 mg during the first part of this study. Owing to drug backorder, patients enrolled later in this study received levetiracetam 500 mg BID. The primary outcome was the change in the neurotoxicity score 6 weeks after drug initiation. The secondary outcome was seizure incidence. A total of 81 patients were enrolled and randomized to 1 week (40 patients) or 6 weeks (41 patients) of prophylactic levetiracetam treatment. The neurotoxicity score slightly improved in the overall cohort between baseline and reassessment. There was no significant difference between groups in neurotoxicity or depression scores. Seizure incidence was low in the entire cohort of patients with 1 patient in each arm experiencing a seizure during the follow-up period. The use of prophylactic levetiracetam did not result in significant neurotoxicity or depression when given for either 1 week or 6 weeks. The incidence of seizure after craniotomy for tumor resection is low regardless of duration of therapy.

QOL-12. Relaxation technique of imagery based story telling reduces manifestation of anxiety in children and adolescents undergoing brain tumor surgery

Children and adolescents undergoing surgical resection of brain tumors are prone to marked psychologic burden. Especially fear of surgery and its consequences like pain or neurologic sequelae is an important issue. Techniques of relaxation might reduce the intensity of the experienced anxiety and therefore might improve quality of life. In this study, we aimed at determining the effect of a standardized imagery story telling on experienced anxiety as quantified by the questionaire KAT III and cardiac frequency (CF) before and after intervention at two time points (before and after surgery). 12 patients (age: 6-17 years) undergoing brain tumor resection were included in the study. KAT III-scores and CF were determined and compared before and after interventions using a dependend t-test. Mean KAT III-score before first intervention was 0.23 (SD: 0.23), while it was 0.15 (SD: 0.21) after (p = 0.11). Mean KAT III-score before second intervention was 0.11 (SD: 0.13), after: 0.05 (SD: 0.9), p = 0.07. Mean CF before first intervention was 77.1 (SD: 10.3), after: 68,36 (SD: 6.8), p = 0.003. Mean CF before second intervention was 71.67 (SD: 9.57), after: 65 (SD: 8.72), p = 0.003. CF was significantly lower post-interventionally after the first and the second intervention. KAT III-score showed a trend to be lower post-interventionally after the second intervention. Hence, our study points at an efficacy of the deployed relaxation technique of imagery story telling in children and adolescents undergoing brain tumor surgery, although it was limited by a small patient number. Further studies with larger patient numbers and a comparison of randomized intervention vs. non-intervention groups are warranted.

Neuropsychiatric Symptoms After Brain Tumor Resection in Children and Adolescents: A Scoping Review

Brain tumors are one of the most common solid tumors in pediatric populations, with their treatments having significant neuropsychiatric impact. The objective of this study was to review the literature on neuropsychiatric sequelae after surgical resection of brain tumors in children and adolescents. Using a scoping method, we reviewed empirical articles describing pediatric patients with brain tumors who underwent partial or total resection and examined major neuropsychiatric domains postoperatively over time. The initial search yielded 15,543 articles. After duplicate removal, abstract screening, and review, 44 articles were included. Cognitive deficits were the most widely studied outcomes and found to be associated with tumor location, operative variables, perioperative complications, treatment types, and psychosocial factors. Cerebellar mutism, or posterior fossa syndrome, commonly co-occurred with emotional and behavioral dysregulation after posterior fossa resections. Depression, anxiety, and somatization were frequently grouped together as "distress," with higher rates among pediatric patients with brain tumor than among healthy peers. Problematic school behaviors, antisocial, and attention-deficit traits were increased; however, several other behaviors (e.g., risky sexual behaviors, substance use) were equal or lower when compared to peers. Posttraumatic stress disorder was highly prevalent and often interfered with social functioning. Delirium, eating disorders, and longer-term outcomes received inadequate attention. Identifying risk factors of neuropsychiatric sequelae and their impact after pediatric brain tumor resection is important for prognostication and the development of tailored management strategies for these children and adolescents.

NCOG-40. AWAKE CRANIOTOMY FOR EXCISION OF BRAIN TUMORS; INITIAL 200 CONSECUTIVE CASES FROM AN LMIC

Abstract In recent years, reports from developed countries have shown that awake craniotomy has been shown to improve outcomes of surgical resection of brain tumors. However, no such data is available from low- and middle-income countries. We retrospectively reviewed 200 cases of awake craniotomy performed at our center for excision of brain tumors during last 5 years, and assessed clinical outcomes. Data was collected from patients’ medical records, and included demographics, tumor location/histology, clinical complains, and functional status. We used Karnofsky performance scale (KPS) to assess function. Extent of resection was determined on post-operative MRI. Statistical analysis was done using SPSS version 22. Seven attending surgeons performed these cases; however, 168 (84%) surgeries were performed by a single surgeon who is the senior author (SA Enam). Mean age was 39.3 ± 11.9 years and 79% (158) were male. Left frontal lobe was the most common location for tumors (50; 25%). Although 52% (104) patients had malignant neoplasms, seizures were the most common presenting symptom in 63% (126) cases followed by motor deficits in 29% (58). The most common tumors were low grade oligodendroglioma (58; 29%%) followed by glioblastoma (42; 21%). Mean length of hospital stay was 3.15 days ± 1.7 days. Gross total resection was achieved in 82 (41%) patients. New intraoperative neurological complains were seen in 31 (15.5%) patients, however, 22 (11%) of these had recovered by median follow-up of 1.4 months. KPS at last follow-up improved in 92 (46%), remained stable in 94 (47%) and deteriorated in 14 (7%) patients. Although absence of a control group decreases the strength of this, with our large sample size we can safely conclude that AC allows maximum safe excision of brain tumors, and offers a good chance of preserving patients’ functional status, along with adequate extent of resection.

Characterization of cortical hemodynamic changes following sensory, visual, and speech activation by intraoperative optical imaging utilizing phase-based evaluation methods.

Alterations within cerebral hemodynamics are the intrinsic signal source for a wide variety of neuroimaging techniques. Stimulation of specific functions leads due to neurovascular coupling, to changes in regional cerebral blood flow, oxygenation and volume. In this study, we investigated the temporal characteristics of cortical hemodynamic responses following electrical, tactile, visual, and speech activation for different stimulation paradigms using Intraoperative Optical Imaging (IOI). Image datasets from a total of 22 patients that underwent surgical resection of brain tumors were evaluated. The measured reflectance changes at different light wavelength bands, representing alterations in regional cortical blood volume (CBV), and deoxyhemoglobin (HbR) concentration, were assessed by using Fourier‐based evaluation methods. We found a decrease of CBV connected to an increase of HbR within the contralateral primary sensory cortex (SI) in patients that were prolonged (30 s/15 s) electrically stimulated. Additionally, we found differences in amplitude as well as localization of activated areas for different stimulation patterns. Contrary to electrical stimulation, prolonged tactile as well as prolonged visual stimulation are provoking increases in CBV within the corresponding activated areas (SI, visual cortex). The processing of the acquired data from awake patients performing speech tasks reveals areas with increased, as well as areas with decreased CBV. The results lead us to the conclusion, that the CBV decreases in connection with HbR increases in SI are associated to processing of nociceptive stimuli and that stimulation type, as well as paradigm have a nonnegligible impact on the temporal characteristics of the following hemodynamic response.

A multicenter observational study of cs-131 seeds embedded in a collagen carrier tile in intracranial brain neoplasms: Trial in progress.

TPS2073 Background: Brachytherapy is an efficacious means for radiation delivery in the treatment of a spectrum of central nervous system tumors. Traditional brachytherapy methods have been limited by uneven dose distribution, complicated workflow, extended procedural times, the cost of dedicated equipment, and frequent adverse events. To address these issues, a permanently implanted device with Cs-131 radiation seeds embedded in a bioresorbable collagen carrier tile (GammaTile [GT], GT Medical Technologies, Tempe, AZ USA) was developed. Described as surgically targeted radiation therapy (STaRT) to distinguish it from external beam radiation therapy, the device is FDA-cleared for use in newly diagnosed malignant intracranial neoplasms and recurrent intracranial tumors, and has demonstrated excellent safety and local control outcomes in early commercial use. Methods: The overarching primary objectives of this multicenter, prospective, observational (phase IV) registry study are to evaluate “real-world” clinical outcomes and patient reported outcomes that measure the safety and efficacy of STaRT using the GT device. The registry is planned for 600 prospectively enrolled subjects at up to 50 enrolling sites. All adult patients undergoing surgical resection of brain tumors of any pathology with intra-operative GT placement are eligible for enrollment, upon consent. Information on patient demographics, tumor pathology, overall survival, adverse events related to radiation or surgery, and quality of life (FACT-Br and LASA) will be collected. Serial MRIs will be collected, and timing of surgical bed recurrence and/or distant recurrence will be collected. Data will be collected at 1-, 3-, 6-, 9-, 12-, 18-, and 24-months, then every 6 months through 5 years. Results will be used to benchmark clinical outcomes of GT therapy, allow for comparisons to other existing treatments, and facilitate the design of future clinical trials. Enrollment opened on November 15, 2020, and seven subjects have been enrolled to date at three centers. This study will be the first observational study of resection plus STaRT, delivered by Cs-131 sources in permanently implanted bioresorbable collagen tile carriers, and will allow for evaluation of this treatment approach in a real world setting, as well as provide an information platform for cross-comparison of results obtained from ongoing GT clinical trials. Clinical trial information: NCT04427384.

SURG-20. USE OF NICO MYRIAD NOVUS DEVICE WITH LIGHT SOURCE AND REAL-TIME STEREOTACTIC NAVIGATION TO OPTIMIZE SURGICAL RESECTION OF DEEP-SEATED TUMORS

Abstract Maximal and safe surgical resection remains a critical component of the standard of care for patients with brain tumors. Stereotactic navigation tools are often incorporated into the surgical planning and implementation. The NICO Myriad NOVUS device couples a light source with the resecting tip to allow enhanced visualization of the surgical cavity and surrounding anatomical structures. At the Cleveland Clinic, we were the first group in the U.S. to start utilizing this augmented technology to maximize the resection of particularly deep-seated brain tumors, using the xenon light and real-time stereotactic navigation of the tool tip with the BrainLAB cranial setting. The navigated tip allows us to reach the deep corners of tumors with or without a tubular retracting device by sparing large corticotomies. Furthermore, the light source within the handheld device is easier to handle and manipulate than a large microscope to illuminate the surgical cavity. In addition, this new tool allows for automated tumor and peri-tumoral tissue harvesting, annotating each sample by location intraoperatively, as well as biological preservation of the harvested tissue for post-surgical molecular analysis. We describe the techniques and advantages of using this novel technology in patients while following and preliminarily reporting their surgical outcomes. With the emergence of novel technological advances, we must adapt as neurosurgeons and develop innovative methods to optimize the surgical resection of brain tumors.

Deep Learning for Automated Delineation of Pediatric Cerebral Arteries on Pre-operative Brain Magnetic Resonance Imaging.

Introduction: Surgical resection of brain tumors is often limited by adjacent critical structures such as blood vessels. Current intraoperative navigations systems are limited; most are based on two-dimensional (2D) guidance systems that require manual segmentation of any regions of interest (ROI; eloquent structures to avoid or tumor to resect). They additionally require time- and labor-intensive processing for any reconstruction steps. We aimed to develop a deep learning model for real-time fully automated segmentation of the intracranial vessels on preoperative non-angiogram imaging sequences.Methods: We identified 48 pediatric patients (10-months to 22-years old) with high resolution (0.5–1 mm axial thickness) isovolumetric, pre-operative T2 magnetic resonance images (MRIs). Twenty-eight patients had anatomically normal brains, and 20 patients had tumors or other lesions near the skull base. Manually segmented intracranial vessels (internal carotid, middle cerebral, anterior cerebral, posterior cerebral, and basilar arteries) served as ground truth labels. Patients were divided into 80/5/15% training/validation/testing sets. A modified 2-D Unet convolutional neural network (CNN) architecture implemented with 5 layers was trained to maximize the Dice coefficient, a measure of the correct overlap between the predicted vessels and ground truth labels.Results: The model was able to delineate the intracranial vessels in a held-out test set of normal and tumor MRIs with an overall Dice coefficient of 0.75. While manual segmentation took 1–2 h per patient, model prediction took, on average, 8.3 s per patient.Conclusions: We present a deep learning model that can rapidly and automatically identify the intracranial vessels on pre-operative MRIs in patients with normal vascular anatomy and in patients with intracranial lesions. The methodology developed can be translated to other critical brain structures. This study will serve as a foundation for automated high-resolution ROI segmentation for three-dimensional (3D) modeling and integration into an augmented reality navigation platform.

Evaluating uptake of multiple fluorescent contrast agents in brain tumors simultaneously using whole animal multi-spectral cryo-imaging.

MRI images of gadolinium-based contrast agents (GBCA's) acquired before surgery are often registered to patients and used to guide surgical resection of intracranial tumors. Yet, the accuracy of these MR images in describing the surgical field degrades as surgery progresses; a well-recognized problem which has prompted efforts to develop new techniques that provide updated guidance information on residual tumor location. These efforts span a wide array of technologies, including image updating with deformation models, intraoperative MRI, and fluorescence guided surgery, among others. However, introduction of a straightforward technique that provides surgeons with a current view of GBCA distribution in real time remains an important goal. In this context, development of a fluorescent agent that recapitulates the kinetic behavior of GBCA's could provide familiar information directly in the surgical field in real time. To advance this strategy, we have begun identifying fluorescent contrast agents that show similar kinetic behavior to GBCA's. Using a novel hyperspectral whole body cryo-imaging system, we acquired high-resolution 3-D volumes of the distribution of multiple candidate fluorophores in whole heads bearing orthotopic brain tumors. Preliminary results reveal significant differences in the distribution of candidate optical agents, some of which show strong similarity to the GBCA uptake. Identification and eventual translation of a reliable GBCA-optical analog could improve and simplify surgical resection of brain tumors.

Ketamine Alleviates Perioperative Depression in Patients Undergoing Intracranial Tumor Resection: A Randomized Controlled Trial

Background: Depressive symptoms occurs more than 40% in neurosurgery. However, no effective measures proved to resolve depression within the increasingly decreased hospital stay. Methods: PASSION was a single-center, randomized, placebo-controlled and double-blinded trial recruited patients from 2017 to 2018 in Beijing Tiantan Hospital, Capital Medical University. Eligible patients were 18 to 65 years old and having elective surgical resection of brain tumor with moderate-to-severe depression. Participants were randomized to receive 1 of 2 treatments: (1) the dosage of 0·5 mg/kg ketamine i.v at dura opened at the speed of 0·75 ml·kg-1·h-1 or (2) the identical volume of normal saline. Outcomes: A total of 84 patients completed the trial, of whom 41 (48·8%) randomly received ketamine and 43 (51·2%) received placebo. The primary outcome of response rate were dramatically increased by ketamine compared with placebo group (17[41·5%] vs 7[16·3%]; risk ratio, 2·55; 95% CI 1·18 to 5·50; p=0·010) at 3 days after surgery. Further, response rate at 2 days (relative risk, 2·10; 95% CI 1·07 to 4·12; p=0·024) and remission rate at discharge (relative risk, 4·20; 95% CI 1·28 to 13·80; p=0·007) were both improved by ketamine compared with placebo. No major adverse event was reported for either group. Interpretation: This trial showed that intraoperatively administered ketamine can dramatically alleviate depressive symptoms in depressive patients undergoing neurosurgery without any psychiatric side effects. These results suggest that ketamine quickly, effectively and safely eases depression, especially within one-week stay in hospital. Trial Registration: www.ClinicalTrial.gov (Identifier: NCT03086148) Funding Statement: This trial is funded by Beijing Municipal Administration of Hospitals Clinical Medical Development of Special Funding Support (code number: ZYLX201708) and Beijing Municipal Science and Technology Commission (code number: D131100005313011). Declaration of Interests: The authors declare no competing interests in this trial. Ethics Approval Statement: The study was approved by local ethics committee and all patients or their legal representatives provided written informed consent. This study followed the Consolidated Standards of Reporting Trials (CONSORT) reporting guideline.

Risk factors and associated complications with unplanned intubation in patients with craniotomy for brain tumor

Patients undergoing surgical resection of a brain tumor have the potential risk for beingintubated post-operatively, which may be associated with significant morbidity and/or mortality after surgery. This study was analyzed various preoperative patient characteristics, postoperative outcomes, and complications to identify risk factors for unplanned intubation (UI) in adult patients undergoing craniotomy for a brain tumor and created a risk score framework for that cohort. Patients undergoing surgery for a brain tumor were identified according to primary Current Procedural Terminology codes, and information found in The American College of Surgeons (ACS) National Surgical Quality Improvement Project (NSQIP) database from 2012 to 2015 was reviewed. A total of 18,642 adult brain tumor patients were included in the ACS-NSQIP. The rate of unplanned intubation in this cohort was 2.30% (4 2 8). The mortality rate of patients who underwent UI after surgical resection of brain tumor was 24.78% compared to an overall mortality of 2.46%. During the first 30 days after surgery, 33% of patients who underwent UI had an unplanned reoperation, compared to 4.76% of patients who did not undergo unplanned intubation. Bivariate and multivariate analyses identified several predictors and computed a risk score for UI. A risk score based on patient factors for those undergoing a craniotomy for a brain tumor predicts the postoperative UI rate. This could aid in surgical decision-making by identify patients at a higher risk of UI, while modifying perioperative management may help prevent UI.

Resting-State Functional Magnetic Resonance Imaging for Brain Tumor Surgical Planning: Feasibility in Clinical Setting

The aim of this study was to introduce resting-state functional magnetic resonance imaging (rest-fMRI) capability for brain tumor surgical planning. rest-fMRI is an emerging functional neuroimaging technique potentially able to provide new insights into brain physiology and to provide useful information regarding brain tumors in preoperative and postoperative settings. rest-fMRI evaluates low-frequency fluctuations in the blood oxygen level-dependent signal while the subject is at rest during magnetic resonance imaging examination. Multiple resting-state networks have been identified, including the somatosensory, language, and visual networks, which are of primary importance for surgical planning. We discuss the feasibility of rest-fMRI examination before and after surgical resection of brain tumors in routine clinical practice and the usefulness of the information obtained for surgical planning in brain tumor resection. rest-fMRI is particularly useful for patients who are unable to cooperate with the task-based paradigm, such as children or patients who are sedated, paretic, or aphasic. Although standardization and validation of rest-fMRI are still ongoing, this technique is feasible and valuable and can be implemented for routine clinical surgical planning.

TRLS-04. NEAR INFRARED FLUORESCENT DYE LOCALIZES BRAIN METASTASIS PRIOR TO DURAL OPENING AND IS MORE SENSITIVE THAN WHITE LIGHT IN BRAIN METASTASIS SURGERY

INTRODUCTION: To improve surgical resection of brain tumors, our lab has pioneered a novel fluorescent dye technique, Second-Window Indocyanine-Green (SWIG), that relies on passive delivery and accumulation of indocyanine-green (ICG) in neoplastic tissue via the enhanced permeability and retention effect. We hypothesize that SWIG can provide early localization of brain metastasis prior to dural opening and can improve identification of surgical margins. METHODS: Subjects were prospectively enrolled in clinical trial after informed consent. Approximately 24 hours prior surgery, subjects were infused intravenously with 2.5mg/kg or 5mg/kg of ICG. Intraoperatively, a dedicated near-infrared (NIR) camera was used to detect ICG signal. After bone flap removal, the NIR imaging system was positioned above the presumed location of tumor. Additional NIR images were obtained after dural opening, corticectomy, and after conventional white-light surgical resection. RESULTS: We enrolled 50 patients with 51 total intraparenchymal brain metastases (23 lung, 7 breast, 8 GU/GI, 4 melanoma, and 7 others). Prior to dural opening, NIR signal was identified in 35 patients at an average depth of 4.3mm with SBR = 5.3 + 3.7. In the seven patients where NIR signal could not be identified prior to dural opening, tumor depth was an average of 8.4mm from cortical surface. Upon dural opening and tumor identification, all 51 tumors demonstrated strong NIR signal with SBR = 6.2 + 2.8. With white light alone, sensitivity/specificity/PPV/NPV for tumor detection was 83%, 94%, 98%, 57%. With NIR, sensitivity/specificity/PPV/NPV for tumor detection was 100%, 29%, 85%, 100%. DISCUSSION: NIR fluorophores are superior to visible light fluorophores in their depth of penetration. All contrast-enhancing brain metastasis accumulate ICG using our SWIG technique, and NIR fluorescence could be used to localize brain metastasis prior to dural opening. NIR fluorophores are likely to represent the next phase in tumor visualization given the rapid growth of fluorophores targeted to systemic cancers.

Postoperative Pulmonary Complications Following Brain Tumor Resection: A National Database Analysis

There is sparse literature that investigates the adverse effects of postoperative pulmonary complication (PPCs) specifically in postcraniotomy tumor patients. In this study, we describe the rate of PPCs, determine predictive factors, and delineate associations with adverse outcomes. The National Surgical Quality Improvement Program (2006-2016) database was queried for patients who underwent craniotomy for brain tumors. A total of 28,700 eligible patients were identified. Univariate tests and/or multivariate logistic regression were used to determine predictors of PPC and associations with adverse outcomes. A total of 19 predictors of PPC across 14 different categories were identified: age 65-79 years (odds ratio [OR] 1.6; P < 0.001), age ≥80 years (OR 2.3; P<0.001), male sex (OR 1.3; P < 0.001), operative time ≥360 minutes (OR 4.3; P < 0.001), operative time 300-359 minutes (OR 2.5; P < 0.001), operative time 240-299 minutes (OR 1.8; P < 0.001), operative time 180-239 minutes (OR 1.3; P<0.001), total functional dependence (OR 3.8; P < 0.001), partial functional dependence (OR 1.7; P < 0.001), insulin-dependent diabetes (OR 1.5; P < 0.001), preoperative dyspnea (OR 1.3; P= 0.01), chronic steroid use (OR 1.4; P<0.001), chronic obstructive pulmonary disease (OR 1.8; P<0.001), preoperative leukocytosis (OR 1.4; P < 0.001), anemia (OR 1.2; P < 0.001), American Society of Anesthesiologists (ASA) classification ≥3 (OR 2.0; P < 0.001), emergency case status (OR 2.0; P < 0.001), and infratentorial lesions (OR 1.4; P < 0.001). PPCs were significantly associated with higher reoperation, readmission, and mortality rates as well as longer length of stay (univariate). There are several predictive factors of PPCs in patients that undergo surgical resection of brain tumors, and PPC development is associated with numerous adverse outcomes. It is critically important to understand and, if possible, mitigate controllable circumstances that may reduce morbidity and mortality associated with PPCs.

Trigonal and Peritrigonal Lesions of the Lateral Ventricle: Presurgical Tractographic Planning and Clinic Outcome Evaluation

Surgery of lesions within the atrium of the lateral ventricle remains a challenging procedure because of the deep location and the relationship to vascular structures. The aim of this study was to determine the usefulness of tractography to evaluate the position of white matter tracts located along the course of the surgical access to trigonal and peritrigonal lesions. Diffusion tensor imaging (DTI) was acquired in 19 patients. All patients underwent surgical resection of brain tumors. Pre- and postoperative clinical conditions were evaluated by a neurosurgeon, using the Karnofsky Performance Status Scale. The corticospinal tract, optic radiation, and arcuate fasciculum were reconstructed because of their location close to the trigonal region. Two neurosurgeons were asked to assess the surgical approach with and without tractography. According to the tractographic reconstructions, the surgical access was chosen from the middle temporal gyrus in 12 patients (63%) and the posterior parietal gyrus in 7 patients (37%), leading to an a priori change in the surgical approach in 14 patients (73%). Six patients (31%) showed new postsurgical transient symptoms, whereas in 2 patients (10%) the deficits were permanent. After 30 days, the Karnofsky Performance Status Scale evaluation showed an improvement or a substantial stability of symptoms in 90% of cases. In 2 patients, a worsening of 30% of clinical performance was appreciable. The use of DTI in preoperative planning of trigonal and peritrigonal lesions may help in description of the best surgical approach for patient; this technique allows to reach the tumors, saving the white matter tracts, when it is possible.

Monopolar 250–500 Hz language mapping: Results of 41 patients

ObjectivesTo determine whether high-frequency 250–500 Hz monopolar stimulation is effective for mapping cortical and subcortical language structures during brain tumor resection. MethodsUsing high-frequency monopolar stimulation, we mapped the speech areas of 41 awake patients undergoing brain tumor resection in the dominant hemisphere, subject to risk of lesions in the cortical and subcortical speech tracts. Patients were tested for object naming, semantic and other language tasks. ResultsMapping was positive in 22 out of 41 patients. Nine patients presented clinical worsening immediately after surgery. Only one patient did not recover after the 30-day follow-up. Nineteen patients showed negative mapping for language tracts, none of whom exhibited worsening of symptoms at the final evaluation. The applied method showed 89% sensitivity and 56% specificity rates. ConclusionsThe applied method was effective in identifying cortical and subcortical speech areas during the surgical resection of brain tumors. SignificanceDetermining whether monopolar high-frequency stimulation is effective for language mapping is important, since it may be very effective in infiltrating tumor areas and nearby edema region.