Bayesian networks for Risk Assessment and postoperative deficit prediction in intraoperative neurophysiology for brain surgery.

PURPOSE: To this day there is no consensus regarding evidence of usefulness of Intraoperative Neurophysiological Monitoring (IONM). Randomized controlled trials have not been performed in the past mainly because of difficulties in recruitment control subjects. In this study, we propose the use of Bayesian Networks to assess evidence in IONM. METHODS: Single center retrospective study from January 2020 to January 2022. Patients admitted for cranial neurosurgery with intraoperative neuromonitoring were enrolled. We built a Bayesian Network with utility calculation using expert domain knowledge based on logistic regression as potential causal inference between events in surgery that could lead to central nervous system injury and postoperative neurological function. RESULTS: A total of 267 patients were included in the study: 198 (73.9%) underwent neuro-oncology surgery and 69 (26.1%) neurovascular surgery. 50.7% of patients were female while 49.3% were male. Using the Bayesian Network´s original state probabilities, we found that among patients who presented with a reversible signal change that was acted upon, 59% of patients would wake up with no new neurological deficits, 33% with a transitory deficit and 8% with a permanent deficit. If the signal change was permanent, in 16% of the patients the deficit would be transitory and in 51% it would be permanent. 33% of patients would wake up with no new postoperative deficit. Our network also shows that utility increases when corrective actions are taken to revert a signal change. CONCLUSIONS: Bayesian Networks are an effective way to audit clinical practice within IONM. We have found that IONM warnings can serve to prevent neurological deficits in patients, especially when corrective surgical action is taken to attempt to revert signals changes back to baseline properties. We show that Bayesian Networks could be used as a mathematical tool to calculate the utility of conducting IONM, which could save costs in healthcare when performed.

Radiogenomic biomarkers for immunotherapy in glioblastoma: A systematic review of magnetic resonance imaging studies.

Background: Immunotherapy is an effective "precision medicine" treatment for several cancers. Imaging signatures of the underlying genome (radiogenomics) in glioblastoma patients may serve as preoperative biomarkers of the tumor-host immune apparatus. Validated biomarkers would have the potential to stratify patients during immunotherapy clinical trials, and if trials are beneficial, facilitate personalized neo-adjuvant treatment. The increased use of whole genome sequencing data, and the advances in bioinformatics and machine learning make such developments plausible. We performed a systematic review to determine the extent of development and validation of immune-related radiogenomic biomarkers for glioblastoma. Methods: A systematic review was performed following PRISMA guidelines using the PubMed, Medline, and Embase databases. Qualitative analysis was performed by incorporating the QUADAS 2 tool and CLAIM checklist. PROSPERO registered: CRD42022340968. Extracted data were insufficiently homogenous to perform a meta-analysis. Results: Nine studies, all retrospective, were included. Biomarkers extracted from magnetic resonance imaging volumes of interest included apparent diffusion coefficient values, relative cerebral blood volume values, and image-derived features. These biomarkers correlated with genomic markers from tumor cells or immune cells or with patient survival. The majority of studies had a high risk of bias and applicability concerns regarding the index test performed. Conclusions: Radiogenomic immune biomarkers have the potential to provide early treatment options to patients with glioblastoma. Targeted immunotherapy, stratified by these biomarkers, has the potential to allow individualized neo-adjuvant precision treatment options in clinical trials. However, there are no prospective studies validating these biomarkers, and interpretation is limited due to study bias with little evidence of generalizability.

No evidence for an association of voxel-based morphometry with short-term non-motor outcomes in deep brain stimulation for Parkinson's disease.

Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an established therapy in advanced Parkinson's disease (PD). Motor and non-motor outcomes, however, show considerable inter-individual variability. Preoperative morphometry-based metrics have recently received increasing attention to explain treatment effects. As evidence for the prediction of non-motor outcomes is limited, we sought to investigate the association between metrics of voxel-based morphometry and short-term non-motor outcomes following STN-DBS in this prospective open-label study. Forty-nine PD patients underwent structural MRI and a comprehensive clinical assessment at preoperative baseline and 6-month follow-up. Voxel-based morphometry was used to assess associations between cerebral volume and non-motor outcomes corrected for multiple comparisons using a permutation-based approach. We replicated existing results associating volume loss of the superior frontal cortex with subpar motor outcomes. Overall non-motor burden, however, was not significantly associated with morphometric features, limiting its use as a marker to inform patient selection and holistic preoperative counselling.

Transcranial Magnetic Stimulation-Based Machine Learning Prediction of Tumor Grading in Motor-Eloquent Gliomas.

BACKGROUND: Navigated transcranial magnetic stimulation (nTMS) is a well-established preoperative mapping tool for motor-eloquent glioma surgery. Machine learning (ML) and nTMS may improve clinical outcome prediction and histological correlation. METHODS: This was a retrospective cohort study of patients who underwent surgery for motor-eloquent gliomas between 2018 and 2022. Ten healthy subjects were included. Preoperative nTMS-derived variables were collected: resting motor threshold (RMT), interhemispheric RMT ratio (iRMTr)-abnormal if above 10%-and cortical excitability score-number of abnormal iRMTrs. World Health Organization (WHO) grade and molecular profile were collected to characterize each tumor. ML models were fitted to the data after statistical feature selection to predict tumor grade. RESULTS: A total of 177 patients were recruited: WHO grade 2-32 patients, WHO grade 3-65 patients, and WHO grade 4-80 patients. For the upper limb, abnormal iRMTr were identified in 22.7% of WHO grade 2, 62.5% of WHO grade 3, and 75.4% of WHO grade 4 patients. For the lower limb, iRMTr was abnormal in 23.1% of WHO grade 2, 67.6% of WHO grade 3%, and 63.6% of WHO grade 4 patients. Cortical excitability score (P = .04) was statistically significantly related with WHO grading. Using these variables as predictors, the ML model had an accuracy of 0.57 to predict WHO grade 4 lesions. In subgroup analysis of high-grade gliomas vs low-grade gliomas, the accuracy for high-grade gliomas prediction increased to 0.83. The inclusion of molecular data into the model-IDH mutation and 1p19q codeletion status-increases the accuracy of the model in predicting tumor grading (0.95 and 0.74, respectively). CONCLUSION: ML algorithms based on nTMS-derived interhemispheric excitability assessment provide accurate predictions of HGGs affecting the motor pathway. Their accuracy is further increased when molecular data are fitted onto the model paving the way for a joint preoperative approach with radiogenomics.

Taking the knife to neurodegeneration: a review of surgical gene therapy delivery to the CNS.

Gene supplementation and editing for neurodegenerative disorders has emerged in recent years as the understanding of the genetic mechanisms underlying several neurodegenerative disorders increases. The most common medium to deliver genetic material to cells is via viral vectors; and with respect to the central nervous system, adeno-associated viral (AAV) vectors are a popular choice. The most successful example of AAV-based gene therapy for neurodegenerative disorders is Zolgensma© which is a transformative intravenous therapy given to babies with spinal muscular atrophy. However, the field has stalled in achieving safe drug delivery to the central nervous system in adults for which treatments for disorders such as amyotrophic lateral sclerosis are desperately needed. Surgical gene therapy delivery has been proposed as a potential solution to this problem. While the field of the so-called regenerative neurosurgery has yielded pre-clinical optimism, several challenges have emerged. This review seeks to explore the field of regenerative neurosurgery with respect to AAV-based gene therapy for neurodegenerative diseases, its progress so far and the challenges that need to be overcome.

Incidence and Risk Factors of Surgical Site Infection After Cranial Surgery for Patients with Brain Tumors: A Systematic Review and Meta-analysis.

BACKGROUND: Surgical site infections after craniotomy (SSI-CRANs) are a serious adverse event given the proximity of the wound to the central nervous system. SSI-CRANs are associated with substantial patient morbidity and mortality. Despite the importance and recognition of this event in other surgical fields, there is a paucity of evidence in the neurosurgical literature devoted to SSI-CRAN specifically in patients after brain tumor surgery. METHODS: Systematic searches of Medline, Embase, and Cochrane Central were undertaken. The primary outcome was the incidence of SSI-CRAN at 30 and 90 days. Secondary outcomes were risk factors for SSI-CRAN. RESULTS: Thirty-seven studies reporting 91,907 patients with brain tumors who underwent cranial surgery were included in the meta-analysis. Pooled incidence of SSI-CRAN at 30 and 90 days was 4.03% (95% CI: 2.94%-5.28%, I2 = 97.3) and 6.17% (95% CI: 3.16%-10.07%, I2 = 97.3), respectively. Specifically, incidence of SSI-CRAN following surgery for posterior fossa tumors was the highest at 9.67% (95% CI: 5.98%-14.09%, I2 = 75.5). Overall pooled incidence of readmission within 30 days and reoperation due to SSI-CRAN were 13.9% (95% CI: 12.5%-15.5%, I2 = 0.0) and 16.3% (95% CI: 5.4%-31.3%, I2 = 72.9), respectively. Risk factors for SSI-CRAN included reintervention (risk ratio [RR] 1.58, 95% CI: 1.22-2.04, I2 = 0.0), previous radiotherapy (RR 1.69, 95% CI: 1.20-2.38, I2 = 0.0), longer duration of operation (mean difference 64.18, 95% CI: 3.96-124.40 minutes, I2 = 90.3) and cerebrospinal fluid (CSF) leaks (RR 14.26, 95% CI: 2.14-94.90, I2 = 73.2). CONCLUSIONS: SSI-CRAN affects up to 1 in 14 patients with brain tumors. High-risk groups include those with reintervention, previous radiotherapy, longer duration of operation, and CSF leaks. Further prospective studies should focus on bundles of care that will reduce SSI-CRAN.

Deep brain stimulation of the subthalamic nucleus in Parkinson disease 2013-2023: where are we a further 10 years on?

Deep brain stimulation has been in clinical use for 30 years and during that time it has changed markedly from a small-scale treatment employed by only a few highly specialized centers into a widespread keystone approach to the management of disorders such as Parkinson's disease. In the intervening decades, many of the broad principles of deep brain stimulation have remained unchanged, that of electrode insertion into stereotactically targeted brain nuclei, however the underlying technology and understanding around the approach have progressed markedly. Some of the most significant advances have taken place over the last decade with the advent of artificial intelligence, directional electrodes, stimulation/recording implantable pulse generators and the potential for remote programming among many other innovations. New therapeutic targets are being assessed for their potential benefits and a surge in the number of deep brain stimulation implantations has given birth to a flourishing scientific literature surrounding the pathophysiology of brain disorders such as Parkinson's disease. Here we outline the developments of the last decade and look to the future of deep brain stimulation to attempt to discern some of the most promising lines of inquiry in this fast-paced and rapidly evolving field.

Glioblastoma and Radiotherapy: a multi-center AI study for Survival Predictions from MRI (GRASP study).

BACKGROUND: The aim was to predict survival of glioblastoma at eight months after radiotherapy (a period allowing for completing a typical course of adjuvant temozolomide), by applying deep learning to the first brain MRI after radiotherapy completion. METHODS: Retrospective and prospective data were collected from 206 consecutive glioblastoma, IDH-wildtype patients diagnosed between March 2014-February 2022 across 11 UK centers. Models were trained on 158 retrospective patients from three centers. Holdout test sets were retrospective (n=19; internal validation), and prospective (n=29; external validation from eight distinct centers).Neural network branches for T2-weighted and contrast-enhanced T1-weighted inputs were concatenated to predict survival. A non-imaging branch (demographics/MGMT/treatment data) was also combined with the imaging model. We investigated the influence of individual MR sequences; non-imaging features; and weighted dense blocks pretrained for abnormality detection. RESULTS: The imaging model outperformed the non-imaging model in all test sets (area under the receiver-operating characteristic curve, AUC p=0.038) and performed similarly to a combined imaging/non-imaging model (p>0.05). Imaging, non-imaging, and combined models applied to amalgamated test sets gave AUCs of 0.93, 0.79, and 0.91. Initializing the imaging model with pretrained weights from 10,000s of brain MRIs improved performance considerably (amalgamated test sets without pretraining 0.64; p=0.003). CONCLUSIONS: A deep learning model using MRI images after radiotherapy, reliably and accurately determined survival of glioblastoma. The model serves as a prognostic biomarker identifying patients who will not survive beyond a typical course of adjuvant temozolomide, thereby stratifying patients into those who might require early second-line or clinical trial treatment.

Neurostimulation for Advanced Parkinson Disease and Quality of Life at 5 Years: A Nonrandomized Controlled Trial.

Importance: Deep brain stimulation of the subthalamic nucleus (STN-DBS) improves quality of life (QOL) in patients with advanced Parkinson disease (PD). However, controlled studies with more than 3 years of follow-up are lacking. Objective: To investigate the long-term effects of STN-DBS on QOL compared with standard-of-care medication (MED). Design, Setting, and Participants: In this prospective, observational, quasi-experimental, longitudinal nonrandomized controlled trial, 183 patients were screened for eligibility and 167 were enrolled from March 1, 2011, to May 31, 2017, at 3 European university centers. Propensity score matching for demographic and clinical characteristics was applied to 108 patients with PD (62 in the STN-DBS group and 46 in the MED group), resulting in a well-balanced, matched subcohort of 25 patients per group. Data analysis was performed from September 2022 to January 2023. Exposure: Treatment for PD of STN-DBS or MED. Main Outcomes and Measures: Assessments included Parkinson's Disease Questionnaire 8 (PDQ-8), Unified PD Rating Scale-motor examination, Scales for Outcomes in PD-activities of daily living (ADL) and motor complications, and levodopa-equivalent daily dose. Within-group longitudinal outcome changes, between-group differences, and correlations of change scores were analyzed. Results: The study population in the analysis included 108 patients (mean [SD] age, 63.7 [8.3] years; 66 [61.1%] male). At 5-year follow-up, PDQ-8 and ADL worsened only in the MED group (PDQ-8 change, -10.9; 95% CI, -19.0 to -2.7; P = .01; ADL change: -2.0; 95% CI, -3.1 to -0.8; P = .002), whereas both outcomes remained stable in the STN-DBS group (PDQ-8 change, -4.3; 95% CI, -13.2 to 4.7; P = .34; ADL change, -0.8; 95% CI, -2.5 to 1.0; P = .38). Changes in PDQ-8 and ADL correlated moderately (rs = .40, P = .008). Furthermore, STN-DBS outcomes were favorable for motor complications (median difference in change scores between STN-DBS and MED, -2.0; 95% CI, -4.0 to -1.0; P = .003), mobility (-1.0; 95% CI, -2.0 to 0; P = .03), and levodopa-equivalent daily dose reduction (-821.4; 95% CI, -1111.9 to -530.8; P < .001). Conclusions and Relevance: This study provides evidence of differences in QOL outcomes at 5-year follow-up between STN-DBS (stable) and MED (worsened), mainly driven by the favorable effect of STN-DBS on mobility (class IIb evidence). The association between changes in QOL and ADL, but not motor impairment or complications, highlights the relative importance of ADL outcomes for long-term DBS assessments. Trial Registration: German ClinicalTrials Registry: DRKS00006735.

Impact of Preoperative Mapping and Intraoperative Neuromonitoring in Minimally Invasive Parafascicular Surgery for Deep-Seated Lesions.

BACKGROUND: Transsulcal tubular retractor-assisted minimally invasive parafascicular surgery changes the surgical strategy for deep-seated lesions by promoting a deficit-sparing approach. When integrated with preoperative brain mapping and intraoperative neuromonitoring (IONM), this approach may potentially improve patient outcomes. In this study, we assessed the impact of preoperative brain mapping and IONM in tubular retractor-assisted neuro-oncological surgery. METHODS: This retrospective single-center cohort study included patients who underwent transsulcal tubular retractor-assisted minimally invasive parafascicular surgery for resection of deep-seated brain tumors from 2016 to 2022. The cohort was divided into 3 groups: group 1, no preoperative mapping or IONM (17 patients); group 2, IONM only (25 patients); group 3, both preoperative mapping and IONM (38 patients). RESULTS: We analyzed 80 patients (33 males and 47 females) with a median age of 46.5 years (range: 1-81 years). There was no significant difference in mean tumor volume (26.2 cm3 [range 1.07-97.4 cm3]; P = 0.740) and mean preoperative depth of the tumor (31 mm [range 3-65 mm], P = 0.449) between the groups. A higher proportion of high-grade gliomas and metastases was present within group 3 (P = 0.003). IONM was related to fewer motor (P = 0.041) and language (P = 0.032) deficits at hospital discharge. Preoperative mapping and IONM were also related to shorter length of stay (P = 0.008). CONCLUSIONS: Preoperative and intraoperative brain mapping and monitoring enhance transsulcal tubular retractor-assisted minimally invasive parafascicular surgery in neuro-oncology. Patients had a reduced length of stay and prolonged overall survival. IONM alone reduces postoperative neurological deficit.

Nonenhancing motor eloquent gliomas: navigated transcranial magnetic stimulation oncobiological signature.

OBJECTIVE: Preoperative grading of nonenhancing motor eloquent gliomas is hampered by a lack of specific imaging surrogates. Tumor grading is crucial for the informed consent discussion before tumor resection. In this paper, the authors hypothesized that navigated transcranial magnetic stimulation (nTMS)-derived metrics could provide significant information to distinguish between high- and low-grade motor eloquent gliomas that present as nonenhancing tumors and therefore contribute to improving patient counseling, timing of treatment, preoperative planning, and intraoperative strategies. METHODS: The authors conducted a retrospective single-center cohort study of patients admitted for tumor surgery between January 2018 and April 2022 with a nonenhancing motor eloquent glioma and preoperative bilateral nTMS mapping. nTMS data including resting motor threshold (RMT), interhemispheric RMT ratio (iRMTr), Cortical Excitability Score (CES), area and volume of cortical activation, and motor evoked potential (MEP) characteristics were obtained and integrated with demographic and clinical data. RESULTS: Thirty patients met the inclusion criteria, and 10 healthy participants were recruited for comparison. Seizures were the most common presenting symptom (25 patients) and WHO grade 3 the most common tumor grade (21 patients). The area and volume of functional cortical activation of both the abductor pollicis brevis and first dorsal interosseous muscles were decreased in healthy participants compared with patients with WHO grade 3 glioma (p < 0.05). An abnormal iRMTr for the lower limbs (16.7% [1/6] WHO grade 2, 76.2% [16/21] WHO grade 3, 100% [3/3] WHO grade 4; p = 0.015) and a higher CES (maximal abnormal CES: 0% [0/6] WHO grade 2, 38% [8/21] WHO grade 3, 66.7% [2/3] WHO grade 4; p = 0.010) were associated with the prediction of high-grade lesions. A total of 7280 MEPs were analyzed. A significant increase in the amplitude and a significant decrease in latency in the MEPs for the first dorsal interosseous and abductor digiti minimi muscles (p < 0.0001) were identified in healthy participants compared with WHO grade 3 glioma patients. CONCLUSIONS: Nonenhancing motor eloquent gliomas have a different impact on both anatomical and functional reorganization of motor areas according to their WHO grading.

Cortical resting motor threshold difference in asleep-awake craniotomy for motor eloquent gliomas: WHO grading influences motor pathway excitability.

Developing neurophysiological tools to predict WHO tumor grade can empower the treating teams for a better surgical decision-making process. A total of 38 patients with supratentorial diffuse gliomas underwent an asleep-awake-sedated craniotomies for tumor removal with intraoperative neuromonitoring. The resting motor threshold was calculated for different train stimulation paradigms during awake and asleep phases. Receiver operating characteristic analysis and Bayesian regression models were performed to analyze the prediction of tumor grading based on the resting motor threshold differences. Significant positive spearman correlations were observed between resting motor threshold excitability difference and WHO tumor grade for train stimulation paradigms of 5 (R = 0.54, P = 0.00063), 4 (R = 0.49, P = 0.002), 3 (R = 0.51, P = 0.001), and 2 pulses (R = 0.54, P = 0.0007). Kruskal-Wallis analysis of the median revealed a positive significant difference between the median of excitability difference and WHO tumor grade in all paradigms. Receiver operating characteristic analysis showed 3 mA difference as the best predictor of high-grade glioma across different patterns of motor pathway stimulation. Bayesian regression found that an excitability difference above 3 mA would indicate a 75.8% probability of a glioma being high grade. Our results suggest that cortical motor excitability difference between the asleep and awake phases in glioma surgery could correlate with tumor grade.

Stratifying quality of life outcome in subthalamic stimulation for Parkinson's disease.

BACKGROUND: Subthalamic nucleus deep brain stimulation (STN-DBS) for Parkinson's disease (PD) improves quality of life (QoL), motor and non-motor symptoms (NMS). However, in previous studies, 43%-49% of patients did not experience clinically relevant postoperative QoL improvement. To inform individualised prediction of postoperative QoL improvement, we developed a stratification analysis of QoL outcomes based on preoperative non-motor total burden, severity of motor progression and motor response in levodopa challenge tests. METHODS: This was a prospective, open-label, multicentre, international study with a 6-month follow-up. A distribution-based threshold identified 'QoL responders' in the PDQuestionnaire-8 Summary Index (PDQ-8 SI). After baseline stratification based on the NMS Scale, Hoehn and Yahr Scale and levodopa response assessed with the Unified PD Rating Scale-III, we compared postoperative QoL response between these strata. To assess the clinical usefulness and statistical feasibility of stratifications, we compared cumulative distribution function curves, respectively PDQ-8 within-stratum variation. RESULTS: All main outcomes improved postoperatively. Based on the 8.1 points threshold for clinically meaningful PDQ-8 SI improvement, only 80/161 patients were classified as 'QoL responders'. The absolute risk reductions for QoL non-response among respective non-motor, motor progression and levodopa response strata were 23%, 8% and 3%, respectively. Only non-motor stratification reduced PDQ-8 within-stratum variation compared with the overall cohort. CONCLUSIONS: Non-motor stratification, but not motor progression or levodopa response stratification, is clinically useful and statistically feasible for personalised preoperative prediction of postoperative QoL outcome of STN-DBS for PD. Our findings highlight that non-motor assessments are necessary components of a case-based, holistic approach of DBS indication evaluations geared towards optimising postoperative QoL outcomes. TRIAL REGISTRATION NUMBER: GermanClinicalTrialsRegister: #6735.

Awake craniotomy during pregnancy: A systematic review of the published literature.

Neurosurgical pathologies in pregnancy pose significant complications for the patient and fetus, and physiological stressors during anesthesia and surgery may lead to maternal and fetal complications. Awake craniotomy (AC) can preserve neurological functions while reducing exposure to anesthetic medications. We reviewed the literature investigating AC during pregnancy. PubMed, Scopus, and Web of Science databases were searched from the inception to February 7th, 2023, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Studies in English investigating AC in pregnant patients were included in the final analysis. Nine studies composed of nine pregnant patients and ten fetuses (one twin-gestating patient) were included. Glioma was the most common pathology reported in six (66.7%) patients. The frontal lobe was the most involved region (4 cases, 44.4%), followed by the frontoparietal region (2 cases, 22.2%). The awake-awake-awake approach was the most common protocol in seven (77.8%) studies. The shortest operation time was two hours, whereas the longest one was eight hours and 29 min. The mean gestational age at diagnosis was 13.6 ± 6.5 (2-22) and 19.6 ± 6.9 (9-30) weeks at craniotomy. Seven (77.8%) studies employed intraoperative fetal heart rate monitoring. None of the AC procedures was converted to general anesthesia. Ten healthy babies were delivered from patients who underwent AC. In experienced hands, AC for resection of cranial lesions of eloquent areas in pregnant patients is safe and feasible and does not alter the pregnancy outcome.

Corrigendum: Fixed-life or rechargeable battery for deep brain stimulation: preference and satisfaction in Chinese patients with Parkinson's disease.

[This corrects the article DOI: 10.3389/fneur.2021.668322.].

Lightfield hyperspectral imaging in neuro-oncology surgery: an IDEAL 0 and 1 study.

Introduction: Hyperspectral imaging (HSI) has shown promise in the field of intra-operative imaging and tissue differentiation as it carries the capability to provide real-time information invisible to the naked eye whilst remaining label free. Previous iterations of intra-operative HSI systems have shown limitations, either due to carrying a large footprint limiting ease of use within the confines of a neurosurgical theater environment, having a slow image acquisition time, or by compromising spatial/spectral resolution in favor of improvements to the surgical workflow. Lightfield hyperspectral imaging is a novel technique that has the potential to facilitate video rate image acquisition whilst maintaining a high spectral resolution. Our pre-clinical and first-in-human studies (IDEAL 0 and 1, respectively) demonstrate the necessary steps leading to the first in-vivo use of a real-time lightfield hyperspectral system in neuro-oncology surgery. Methods: A lightfield hyperspectral camera (Cubert Ultris ×50) was integrated in a bespoke imaging system setup so that it could be safely adopted into the open neurosurgical workflow whilst maintaining sterility. Our system allowed the surgeon to capture in-vivo hyperspectral data (155 bands, 350-1,000 nm) at 1.5 Hz. Following successful implementation in a pre-clinical setup (IDEAL 0), our system was evaluated during brain tumor surgery in a single patient to remove a posterior fossa meningioma (IDEAL 1). Feedback from the theater team was analyzed and incorporated in a follow-up design aimed at implementing an IDEAL 2a study. Results: Focusing on our IDEAL 1 study results, hyperspectral information was acquired from the cerebellum and associated meningioma with minimal disruption to the neurosurgical workflow. To the best of our knowledge, this is the first demonstration of HSI acquisition with 100+ spectral bands at a frame rate over 1Hz in surgery. Discussion: This work demonstrated that a lightfield hyperspectral imaging system not only meets the design criteria and specifications outlined in an IDEAL-0 (pre-clinical) study, but also that it can translate into clinical practice as illustrated by a successful first in human study (IDEAL 1). This opens doors for further development and optimisation, given the increasing evidence that hyperspectral imaging can provide live, wide-field, and label-free intra-operative imaging and tissue differentiation.

Awake minimally invasive parafascicular approach to a language eloquent brain tumour-surgical video.

Deep-seated brain tumours are surgically challenging to access. When planning approaches to these lesions, it is important to take into account eloquent cortical areas, grey matter nuclei, and subcortical white matter tracts. Traditionally, access to deep-seated lesions would require brain retraction; however, this is associated with secondary brain damage, which may impair neurological function. A trans-sulcal minimally invasive parafascicular approach allows gentle splitting of brain fibres and is thought to splay rather than sever white matter tracts. This is particularly important when approaching medially located, language-eloquent tumours, which lack brain surface expression. This video describes a minimally invasive approach to a deep-seated, language-eloquent brain tumour. We utilized preoperative cortical and subcortical planning to define a safe surgical corridor. We then demonstrate using intraoperative neuro-monitoring and mapping of the motor and language functions to define the boundaries of surgical resection. We find trans-sulcal minimally invasive parafascicular approach to be a safe and effective technique when approaching language-eloquent lesions medial to the main language subcortical networks.

Butterfly gliomas: a time for stratified management?

Butterfly glioblastomas (bGBM) are a rare subset of WHO grade IV tumours that carry a poor prognosis with a median survival ranging between 3.3 to 6 months. Given their poor prognosis, there is debate over whether histological diagnosis with a biopsy or any surgical or oncological intervention alters disease progression. With this in mind, we reviewed our experience as a high-volume unit to evaluate management decisions and outcomes. A retrospective analysis was undertaken (January 2009 to June 2021) of the electronic patient records of a large neurosurgical centre. We assessed patient demographics, initial clinical presentation, tumour characteristics, clinical management and overall survival (Kaplan-Meier estimator, log-rank analysis and cox proportional hazard analysis). Eighty cases of bGBM were identified. These patients were managed with biopsy ± adjuvant therapy (36), with radiotherapy alone without biopsy (3), or through surgical resection (3). Thirty-eight cases of suspected bGBM were managed conservatively, receiving no oncological treatment or surgical resection/biopsy for histological diagnosis. Those managed conservatively and with radiotherapy without biopsy were diagnosed at neuro-oncology multidisciplinary meeting (MDT) based on clinical presentation and radiological imaging. No significant difference in survival was seen between conservative management compared with single adjuvant treatment (p = 0.69). However, survival was significantly increased when patients received dual adjuvant chemoradiotherapy following biopsy or resection (p = 0.002). A Cox Proportional Hazards model found that survival was significantly impacted by the oncology treatment (p < 0.001), but was not significantly related to potential confounding variables such as the patient's age (p = 0.887) or KPS (p = 0.057). Butterfly glioblastoma have a poor prognosis. Our study would suggest that unless a patient is planned for adjuvant chemoradiotherapy following biopsy, they should be managed conservatively. This avoids unnecessary procedural interventions with the associated morbidities and costs.