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Objective: Epilepsy is commonly associated with low-grade gliomas (LGGs), impacting patients' well-being. While resection is the primary treatment, seizures can persist postoperatively in 27%-55% of cases. The authors aimed to evaluate an electrocorticography (ECoG) and navigated transcranial magnetic stimulation (nTMS)-tailored supratotal resection (ETT-SpTR) for LGG in controlling seizures, preserving neurological function, and enhancing treatment effectiveness., Methods: The authors retrospectively analyzed a prospectively enrolled cohort of patients with LGG presenting with epileptic seizures with ictal/interictal activity on electroencephalography (EEG) who underwent resective surgery. The authors performed preoperative nTMS to identify functional cortical areas. ECoG was used to guide the removal of the high-risk epilepsy cortical areas (HREAs). Patients were divided into two groups: group I, the control group, underwent gross-total resection alone, whereas group II patients underwent removal of HREAs identified by ECoG (ETT-SpTR). Resection avoided functionally eloquent areas as identified on nTMS, checked with cortical mapping. Postoperative seizure outcome was assessed using the Engel classification., Results: Fifteen patients who underwent LGG resection between January and July 2023 were included. Among 24 identified nTMS-positive points, none were included in the resection. Overall, 73.3% of patients (11/15) showed positive intraoperative ECoG, with better outcomes in group II (85.7% Engel class IA) than in group I (25% Engel class IA) at the follow-up (p = 0.02, OR 0.5 [95% CI 0.035-7.10], RR 0.19 [95% CI 0.03-1.2]). Seizure control was significantly better in group II, with no notable differences in postoperative transient neurological deficits between the two groups (p = 0.45). No permanent neurological deficits were observed during follow-up. Statistical analysis revealed significant differences between the two groups (p < 0.05)., Conclusions: This preliminary study affirms the predictive value of TMS for postoperative neurological status and safety in epileptic patients. Intraoperative ECoG effectively identified peritumoral HREAs. ETT-SpTR significantly improved epileptic outcomes, preserving functions without permanent neurological worsening. Additional resection targets the HREAs in the temporal, frontal, and parietal lobes.

Background: Frontal lobe epilepsy is pharmacoresistant in 30% of cases, constituting 10-20% of epilepsy surgeries. For cases of no lesional epilepsy (negative MRI), frontal lobectomy is a crucial treatment, historically involving Frontal Anatomical Lobectomy (AFL) with a 33.3% complication risk and 55.7% seizure control., Methods: We describe Frontal Functional Lobectomy (FFL), in which the boundaries are defined on the patient's functional cortico-subcortical areas, recognized with advanced intraoperative technologies such as tractography and navigated transcranial magnetic stimulation (nTMS)., Conclusions: The FFL allows for a broader resection with a lower rate of postoperative complications than the AFL., (© 2024. The Author(s).)

Objective: 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., Methods: 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., Results: 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., Conclusions: 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.

Background: The aim of this paper was to understand the role of prophylaxis with levetiracetam at skin incision in preventing convulsive intraoperative seizures (IOS) during neurosurgical procedures with and without intraoperative neuromonitoring (IONM)., Methods: Authors retrospectively reviewed the Institutional database for cases of supratentorial brain tumors undergoing surgical resection performed from January 2021 to October 2022. Patients were operated on both under general anesthesia and awake, using motor-evoked potentials (MEP) and direct cortical stimulation for cortical mapping. 1000 mg ev of Levetiracetam before skin incision in case of a history of seizures was administrated. We excluded all infratentorial cases., Results: Three hundred fisty three consecutive cases were retrieved. IOS occurred in 22 patients (6.2%). Prophylaxis with Levetiracetam was administered in 149 patients, and IOS occurred in 16 cases (10.7%) in this group of patients. The IOS rate in the case of no Levetiracetam prophylaxis administration (3.5%) was significantly lower (P<0.001, OR=3.38 [1.35-8.45], RR=3.12 [1.32-7.41]). The Penfield technique stimulation evoked seven of all 22 IOS reported (31.8%) (P=0.006, RR 5.4 [1.44 -20.58], OR 21 [2.3-183.9]), and the train-of-five technique stimulation caused two of all registered IOS (8.7%) (P=0.2, RR 2.3 [0.99-5.67], OR 6.5 [0.55-76.17]). Transcranial MEPs evoked no IOS., Conclusions: Under levetiracetam prophylaxis, the IOS rate was not significantly lower than in the group of patients without Levetiracetam prophylaxis, regardless of the histology of the tumor and IONM. Neither the transcranial stimulation (MEP) nor train-of-five technique stimulation increases the risk of convulsive IOS, as Penfield technique stimulation does.

Background and Objectives: We aimed to assess the reliability of preoperative navigated transcranial magnetic stimulation (nTMS) maps for motor function as visualized intraoperatively with augmented reality heads-up display and to assess its accuracy via direct point-by-point comparison with the gold-standard direct cortical stimulation (DCS)., Methods: From January 2022 to January 2023, candidates for surgical removal of lesions involving the motor pathways underwent preoperative nTMS assessment to obtain cortical maps of motor function. Intraoperatively and before tumor removal, nTMS maps were superimposed on the cortical surface, and DCS was performed on positive points with increasing current intensity until obtaining a positive response at 16 mA. The outcome of each stimulation was recorded to obtain discrimination metrics., Results: Twelve patients were enrolled (5 females [42%] vs 7 males [58%], mean age 62.9 ± 12.8 years), for a total of 304 investigated points. Agreement between nTMS and DCS was moderate (κ = 0.43, P < .005), with 0.66 (0.53-0.78) sensitivity, 0.87 (0.82-0.90) specificity, 0.50 (0.39-0.62) positive predictive values, 0.93 (0.89-0.95) negative predictive value, and 0.83 (0.79-0.87) accuracy. A loss of accuracy was observed with higher DCS current intensities., Conclusion: We performed a point-by-point validation of preoperative nTMS maps for motor function using augmented reality visualization. The high negative predictive value and low positive predictive values highlight nTMS reliability to visualize safe cortical zones but not to identify critical functional areas, confirming previous findings of nTMS maps for the language function and suggesting the need for combined use of nTMS maps and DCS for optimal maximal safe resection., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Objective: The aim of the present study was to determine the position of the 3 sensory branches of the trigeminal nerve in the preganglionic tract using intraoperative neurophysiological mapping., Methods: We included consecutive adult patients who underwent neurosurgical treatment of cerebellopontine angle lesions. The trigeminal nerve was antidromically stimulated at 3 sites along its circumference with different stimulus intensities at a distance of ≤1 cm from the brainstem. The sensory nerve action potentials (SNAPs) were recorded from each main trigeminal branch (V1 [ophthalmic branch], V2 [maxillary branch], and V3 [mandibular branch])., Results: We analyzed 13 patients. The stimulation points at which we obtained the greatest number of congruous and exclusive SNAPs (SNAPs only on the stimulated branch) was the stimulation point for V3 (20.7%). The stimulation intensity at which we obtained the highest number of congruent and exclusive SNAPs with the stimulated branch was 0.5 mA., Conclusions: Using our recording conditions, trigeminal stimulation is a reliable technique for mapping the V3 and V1 branches using an intensity not exceeding 0.5. However, reliable identification of the fibers of V2 is more difficult. Stimulation of the trigeminal nerve can be a reliable technique to identify the V3 and V1 branches if rhizotomy of these branches is necessary., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The non-enhancing peritumoral area (NEPA) is defined as the hyperintense region in T2-weighted and fluid-attenuated inversion recovery (FLAIR) images surrounding a brain tumor. The NEPA corresponds to different pathological processes, including vasogenic edema and infiltrative edema. The analysis of the NEPA with conventional and advanced magnetic resonance imaging (MRI) was proposed in the differential diagnosis of solid brain tumors, showing higher accuracy than MRI evaluation of the enhancing part of the tumor. In particular, MRI assessment of the NEPA was demonstrated to be a promising tool for distinguishing high-grade gliomas from primary lymphoma and brain metastases. Additionally, the MRI characteristics of the NEPA were found to correlate with prognosis and treatment response. The purpose of this narrative review was to describe MRI features of the NEPA obtained with conventional and advanced MRI techniques to better understand their potential in identifying the different characteristics of high-grade gliomas, primary lymphoma and brain metastases and in predicting clinical outcome and response to surgery and chemo-irradiation. Diffusion and perfusion techniques, such as diffusion tensor imaging (DTI), diffusional kurtosis imaging (DKI), dynamic susceptibility contrast-enhanced (DSC) perfusion imaging, dynamic contrast-enhanced (DCE) perfusion imaging, arterial spin labeling (ASL), spectroscopy and amide proton transfer (APT), were the advanced MRI procedures we reviewed., Competing Interests: The authors declare no conflict of interest.

Background: The critical role of different adjuncts in improving the neurological outcome in intrinsic brain lesions affecting eloquent areas is demonstrated by their more diffuse utilization. Neurosurgeons often rely on preoperative and intraoperative diffusion tensor imaging tractography to improve the operative strategy and prognosis. We aimed to identify and validate a diffusion tensor imaging-based classification considering the relationship between the brain lesion and the corticospinal tract to predict a >50% reduction of motor evoked potentials (MEPs) during surgical excision of lesions involving the motor pathways., Methods: We included patients consecutively enrolled at our institution between April 2020 and September 2022 with 3 patterns of increasing complexity according to the relationship between the lesion and the corticospinal tract as identified on preoperative diffusion tensor imaging. Outcome measures were >50% reduction in intraoperative MEPs and neurological outcome defined as unchanged, improved, or worsened., Results: The study included 83 patients. A statistically significant linear trend between higher rates of reduction of MEPs and higher classification grades was observed (P = 0.001), with sensitivity 0.60, specificity 0.88, accuracy 0.83, and area under the curve 0.75. Higher grades were associated with worse neurological outcomes (P = 0.02)., Conclusions: The classification proved reliable in anticipating reduction in intraoperative MEPs and in predicting neurological outcome. Using this classification in patients undergoing surgery for lesions involving the motor pathways could help in counseling the patient, surgical planning, enhancing teamwork of operating room personnel, and improving the patient's prognosis., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: The role of visual evoked potentials (VEPs) monitoring during neurosurgical procedure in patient remains unclear. The purpose of our study was to determine the feasibility of intraoperative VEP recording using a strip cortical electrode during surgical resection of intracranial lesions., Methods: In this prospective, monocentric, observational study, we enrolled consecutive patients undergoing neurosurgical procedure for intracranial lesions. After dural opening, a cortical strip was positioned on the lateral occipital surface. Flash VEPs were continuously recorded using both subdermal corkscrew electrodes and strip electrodes. An electroretinogram was also recorded to guarantee delivery of adequate flash stimuli to the retina., Results: We included 10 patients affected by different intracranial lesions. Flash VEPs were recorded using subdermal corkscrew electrodes in all patients except 1 in whom they were never identified during the recording. Flash VEPs were recorded using strip electrodes in all patients and showed a polyphasic morphology with a significantly larger amplitude compared with that of flash VEPs measured using subdermal corkscrew electrodes. No patient reported worsened postoperative vision and a >50% decrease in the VEPs amplitude was never registered., Conclusions: We have reported for the first time in the literature that VEP monitoring during a neurosurgical procedure is feasible via a cortical strip located on the occipital surface. The technique demonstrated greater stability and a larger amplitude compared with recordings with scalp electrodes, facilitating identification of any changes. Studies with more patients are needed to assess the clinical reliability of the technique., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: 5-Aminolevulinic acid (5-ALA) fluorescence can maximize perirolandic glioblastoma (GBM) resection with low rates of postoperative sequelae. Our purpose was to present the outcomes of our experience and compare them with other literature reports to investigate the potential influence of different intraoperative monitoring strategies and to evaluate the role of intraoperative data on neurological and radiological outcomes in our series., Methods: We retrospectively analyzed our prospectively collected database of GBM involving the motor pathways. Each patient underwent tumor exeresis with intraoperative 5-ALA fluorescence visualization. Our monitoring strategy was based on direct stimulation (DS), combined with cortical or transcranial MEPs. The radiological outcome was evaluated with CRET vs. residual tumor, and the neurological outcome as improved, unchanged, or worsened. We also performed a literature review to compare our results with state-of-the-art on the subject., Results: Sixty-five patients were included. CRET was 63.1%, permanent postoperative impairment was 1.5%, and DS's lowest motor threshold was 5 mA. In the literature, CRET was 25-73%, permanent postoperative impairment 3-16%, and DS lowest motor threshold was 1-3 mA. Our monitoring strategy identified a motor pathway in 60% of cases in faint fluorescent tissue, and its location in bright/faint fluorescence was predictive of CRET (p < 0.001). A preoperative motor deficit was associated with a worse clinical outcome (p < 0.001). Resection of bright fluorescent tissue was stopped in 26%, and fluorescence type of residual tumor was associated with higher CRET grades (p < 0.001)., Conclusions: Based on the data presented and the current literature, distinct monitoring strategies can achieve different onco-functional outcomes in 5-ALA-guided resection of a glioblastoma (GBM) motor pathway. Intraoperatively, functional and fluorescence data close to a bright/vague interface could be helpful to predict onco-functional outcomes., (© 2022. The Author(s).)

Purpose: Glioblastoma (GBM) is associated with a poorer prognosis when leptomeningeal dissemination (LMD) occurs. Recently, the role of both ventricular entry (VE) during surgery and subventricular zone localization of tumors in promoting LMD in GBM patients has been debated. This article investigates the role of VE in causing LMD in GBM patients., Methods: We conducted a retrospective analysis of GBMs operated on at our Institution between March 2018 and December 2020. We collected pre- and post-surgical images, anamnestic information, and surgical reports., Results: Two hundred cases were collected. The GBM localization was periventricular in 69.5% of cases, and there was a VE during the surgical procedure in 51% of cases. The risk of post-surgical LMD in the case of VE was 16%. The rate of LMD was higher in the case of VE than not-VE (27.4% vs. 4%, p < 0.0001). The rate of LMD in periventricular GBM was 19% (p = 0.1131)., Conclusion: According to our data, VE is an independent factor associated with a higher rate of post-surgical LMD, and the periventricular localization is not independently correlated to this negative outcome. Neurosurgeons should avoid VE when possible. The correct surgical strategy should be founded on balancing the need for maximal EOR and the risks associated with VE., (© 2022. The Author(s).)

Introduction: The incidence of asymptomatic colloid cysts is increasing due to the widespread use of neuroimaging tools. According to previous works, familial forms (within first-degree relatives) represent 5-25% of the cases, and it is not clear whether they display specific features influencing the clinical behavior of the disease., Evidence Acquisition: We reviewed the literature to extract data from papers dealing with familial colloid cysts. For comparison, previous series dealing with the natural history of sporadic cases were identified. Also, we present two more cases of familiar colloid cysts from our experience., Evidence Synthesis: Fifty-one patients (23 reports, plus our cases) were analyzed from the literature. Familial cases showed a younger age at diagnosis (P=0.02) and fewer asymptomatic cases (P<0.001) compared to non-familial colloid cysts. The odds ratio and relative risk of needing surgery with a positive family history for surgical cyst removal were respectively 17.5 (CI: 1.6-197.4) and 1.9 (CI: 0.71 - 5.1). Screening of other family members identified further colloid cysts in 4% of families., Conclusions: Familial colloid cysts show a higher percentage of younger and symptomatic patients compared to non-familiar forms. A positive family history for surgical evacuation is a predictor for a similar outcome. This could indicate a predisposition to an earlier formation and faster growth, and the need for a stricter follow-up in asymptomatic patients. If confirmed in the future, this could suggest a review of the criteria for cyst treatment and extend the surgical indication to asymptomatic familial cases.

Introduction: Oncological aggressiveness and the ability to present distant localizations are known in high-grade gliomas (HGGs), but the knowledge about the possible aggressiveness of LGGs is scarce, especially concerning possible spinal localization., Evidence Acquisition: A systematic search of low-grade gliomas (LGGs) with spinal localization on the three primary online databases (PubMed/MEDLINE, Embase, and Cochrane) was conducted. We included adult patients with histological diagnosis of intracranial LGG and specified WHO grade showing a remote spinal localization during follow-up. Additionally, we present a case of a left temporal LGG presenting a spinal localization fourteen years after the first appearance. We compared the survival rates of LGGs in our series with those of LGGs without spinal localizations., Evidence Synthesis: Seven articles dealing with the subject and eight patients were considered (including our case), with a mean age at diagnosis of 42.25 years (range 26-69 years). The mean latency between a diagnosis of intracranial LGGs and a spinal localization occurrence was 7.37 years (range 2-14 years), and an increased WHO grade of the spinal localization compared to the brain LGG was observed in all patients. There was no sign of intracranial progression at the time of spinal glioma diagnosis in four cases, including ours. Survival at ten years was 28% against a 10-year survival rate of 65-71% for LGGs without distant localization, as reported in the literature., Conclusions: Spinal metastasis of intracranial LGGs is an adverse prognostic factor. Surgical violation of ventricles can play a role in the pathophysiology of CSF spread of tumor cells in LGGs.

Radiomics defines a set of techniques for extraction and quantification of digital medical data in an automated and reproducible way. Its goal is to detect features potentially related to a clinical task, like classification, diagnosis, prognosis, and response to treatment, going beyond the intrinsic limits of operator-dependency and qualitative description of conventional radiological evaluation on a mesoscopic scale. In the field of neuro-oncology, researchers have tried to create prognostic models for a better tumor diagnosis, histological and biomolecular classification, prediction of response to treatment, and identification of disease relapse. Concerning glioma surgery, the most significant aid that radiomics can give to surgery is to improve tumor extension detection and identify areas that are more prone to recurrence to increase the extent of tumor resection, thereby ameliorating the patients' prognosis. This chapter aims to review the fundamentals of radiomics models' creation, the latest advance of radiomics in neuro-oncology, and possible radiomic features associated with the extent of resection in the brain gliomas., (© 2022. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Background: The Subdural Hematoma in the Elderly (SHE) score has been recently developed to assess the 30-day mortality in acute and chronic subdural hematomas in patients >65 years and has shown good reliability. We aimed to validate the SHE score's accuracy to predict 30-day mortality on a homogeneous cohort of patients undergoing surgical chronic subdural hematoma evacuation at our Institution. We also investigated whether the SHE score could reliably predict the occurrence of 30-day chronic subdural hematoma recurrence needing surgery., Methods: We included patients from our prospectively collected database from January 2018 to January 2021. Patients with the availability of the following information were enrolled: age, Glasgow Coma Scale score on admission, hematoma volume, medical history, and outcome at 30 days. The SHE score was calculated for each patient, and the association between greater scores and 30-day mortality was investigated and its ability to predict 30-day and disease recurrence. Statistical significance was assessed for P < 0.05., Results: Three hundred twenty-one patients were included. Of them, 40 (12.5%) displayed mortality within 30-day: specifically, 0% of the group of patients with SHE score = 0, 4.3% of SHE score = 1, 14.5% of SHE score = 2, 39.3% of SHE score = 3, and 37.5% of SHE score = 4, with a statistically significant linear trend between greater SHE scores and 30-day mortality rates (P < 0.001, area under the curve 0.75 [0.67-0.82]). No significant association of the SHE score with the risk of recurrence needing surgery was detected (P = 0.4)., Conclusions: The SHE score proved helpful in predicting 30-day mortality in patients with chronic subdural hematomas, but no utility was observed to predict disease recurrence., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Remote dysconnectivity following cerebellar ischaemic stroke may have a negative impact on supratentorial brain tissue. Since the cerebellum is connected to the individual cerebral lobes via contralateral tracts, cerebellar lesion topography might determine the distribution of contralateral supratentorial brain tissue changes. We investigated (i) the occurrence of delayed cerebral atrophy after cerebellar ischaemic stroke and its relationship to infarct volume; (ii) whether cerebellar stroke topography determines supratentorial atrophy location; and (iii) how cortical atrophy after cerebellar stroke impacts clinical outcome. We performed longitudinal volumetric MRI analysis of patients with isolated cerebellar stroke from the Swiss Stroke Registry database. Stroke location and volume were determined at baseline MRI. Delayed cerebral atrophy was measured as supratentorial cortical volumetric change at follow-up, in contralateral target as compared to ipsilateral reference-areas. In patients with bilateral stroke, both hemispheres were analysed separately. We obtained maps of how cerebellar lesion topography, determines the probability of delayed atrophy per distinct cerebral lobe. Clinical performance was measured with the National Institutes of Health Stroke Scale and modified Rankin Scale. In 29 patients (age 58 ± 18; 9 females; median follow-up: 6.2 months), with 36 datasets (7 patients with bilateral cerebellar stroke), delayed cerebral atrophy occurred in 28 (78%) datasets. A multivariable generalized linear model for a Poisson distribution showed that infarct volume (milliliter) in bilateral stroke patients was positively associated with the number of atrophic target areas (Rate ratio = 1.08; P = 0.01). Lobe-specific cerebral atrophy related to distinct topographical cerebellar stroke patterns. By ordinal logistic regression (shift analysis), more atrophic areas predicted higher 3-month mRS scores in patients with low baseline scores (baseline score 3-5: Odds ratio = 1.34; P = 0.02; baseline score 0-2: OR = 0.71; P = 0.19). Our results indicate that (i) isolated cerebellar ischaemic stroke commonly results in delayed cerebral atrophy and stroke volume determines the severity of cerebral atrophy in patients with bilateral stroke; (ii) cerebellar stroke topography affects the location of delayed cerebral atrophy; and (iii) delayed cerebral atrophy negatively impacts clinical outcome., (© The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain.)

Meningiomas as anatomo-pathological entities were first described in the sixteenth century, but it was Harvey Cusching who in 1922 proposed to identify them with the term "meningioma". They are the most common intracranial tumors, occur between middle and late age and prefer female sex. The symptoms depend on their position with respect to the brain regions. These are mostly benign neoplasms, but there are atypical and even malignant forms. Plaque meningioma refers to a specific macroscopic aspect of the meningioma, due to diffuse dural involvement and usually with extracranial extension. We report here a case of plaque convex meningioma with typical grade I. Key Words: En plaque, Meningioma, WHO Meningioma.

Background:  The introduction of exoscopes in neurosurgery has been welcomed due to their maneuverability, ergonomics, and low-profile frame. 3D devices have further enabled a better stereoscopic visualization. Reports on their application, albeit more and more frequent, are still at their beginning stages. We present our experience with the Olympus ORBEYE 4K-3D exoscope for major cranial procedures. The strengths and weaknesses of the exoscope are presented, and the nuances associated with the learning curve are illustrated., Methods:  Over 2 weeks, patients undergoing surgery for major cranial pathologies were offered to participate in this evaluation of the Olympus ORBEYE 4K-3D exoscope. Information on the use of the exoscope was collected to assess the features and struggles in the learning curve. A comparison with the operating microscope was made., Results:  Fourteen patients with different intracranial pathologies were operated on with the exoscope. No surgery-related complications occurred. The microsurgical part was performed with the exoscope in six cases. The exoscope was used for 72.9% (±37.5%) of the whole microsurgical time vs. 27.1% (±37.5%) microscope time ( p  = 0.02)., Conclusion:  The Olympus ORBEYE 4K-3D exoscope represents a useful evolution of the operating microscope. It requires time to overcome potential difficulties, mostly related to previous motor schemes acquired with operating microscopes. Its features could represent the basis for a paradigm shift in microsurgery., Competing Interests: None declared., (Thieme. All rights reserved.)

Specific anatomical patterns are seen in various diseases affecting the brain. Clinical studies on the topography of pathologies are often limited by the absence of a normalization of the prevalence of pathologies to the relative volume of the affected anatomical structures. A comprehensive reference on the relative volumes of clinically relevant anatomical structures serving for such a normalization, is currently lacking. The analyses are based on anatomical high-resolution three-dimensional T1-weighted magnetic resonance imaging data of 30 healthy Caucasian volunteers, including 14 females (mean age 37.79 years, SD 13.04) and 16 males (mean age 38.31 years, SD 16.91). Semi-automated anatomical segmentation was used, guided by a neuroanatomical parcellation algorithm differentiating 96 structures. Relative volumes were derived by normalizing parenchymal structures to the total individual encephalic volume and ventricular segments to the total individual ventricular volume. The present investigation provides the absolute and relative volumes of 96 anatomical parcellation units of the human encephalon. A larger absolute volume in males than in females is found for almost all parcellation units. While parenchymal structures display a trend towards decreasing volumes with increasing age, a significant inverse effect is seen with the ventricular system. The variances in volumes as well as the effects of gender and age are given for each structure before and after normalization. The provided atlas constitutes an anatomically detailed and comprehensive analysis of the absolute and relative volumes of the human encephalic structures using a clinically oriented parcellation algorithm. It is intended to serve as a reference for volume-standardization in clinical studies on the topographic prevalence of pathologies.

Background: Current imaging-based discrimination between radiation necrosis versus recurrent glioblastoma contrast-enhancing lesions remains imprecise but is paramount for prognostic and therapeutic evaluation. We examined whether patients with radiation necrosis exhibit distinct patterns of blood oxygenation-level dependent fMRI cerebrovascular reactivity (BOLD-CVR) as the first step to better distinguishing patients with radiation necrosis from recurrent glioblastoma compared with patients with newly diagnosed glioblastoma before surgery and radiotherapy. Methods: Eight consecutive patients with primary and secondary brain tumors and a multidisciplinary clinical and radiological diagnosis of radiation necrosis, and fourteen patients with a first diagnosis of glioblastoma underwent BOLD-CVR mapping. For all these patients, the contrast-enhancing lesion was derived from high-resolution T1-weighted MRI and rendered the volume-of-interest (VOI). From this primary VOI, additional 3 mm concentric expanding VOIs up to 30 mm were created for a detailed perilesional BOLD-CVR tissue analysis between the two groups. Receiver operating characteristic curves assessed the discriminative properties of BOLD-CVR for both groups. Results: Mean intralesional BOLD-CVR values were markedly lower in radiation necrosis than in glioblastoma contrast-enhancing lesions (0.001 ± 0.06 vs. 0.057 ± 0.05; p = 0.04). Perilesionally, a characteristic BOLD-CVR pattern was observed for radiation necrosis and glioblastoma patients, with an improvement of BOLD-CVR values in the radiation necrosis group and persisting lower perilesional BOLD-CVR values in glioblastoma patients. The ROC analysis discriminated against both groups when these two parameters were analyzed together (area under the curve: 0.85, 95% CI: 0.65-1.00). Conclusions : In this preliminary analysis, distinctive intralesional and perilesional BOLD-cerebrovascular reactivity patterns are found for radiation necrosis.

Background: In patients with steno-occlusive disease, recent findings suggest that hemodynamic alterations may also be associated with crossed cerebellar diaschisis (CCD) rather than a functional disruption alone., Purpose: To use a quantitative multiparametric hemodynamic MRI to gain a better understanding of hemodynamic changes related to CCD in patients with unilateral anterior circulation stroke., Study Type: Prospective cohort study., Population: Twenty-four patients (25 datasets) with symptomatic unilateral anterior circulation stroke., Field Strength/sequence: 3T/two sequences: single-shot (echo-planar imaging) EPI sequence and T 2 * gradient echo perfusion-weighted imaging study., Assessment: The presence of CCD was inferred from the cerebellar asymmetry index (CAI) of the blood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR) exam, which was calculated from the mean BOLD-CVR and standard deviation of the CAI of the healthy control group. For all perfusion-weighted (PW)-MRI parameters, the cerebellar and middle cerebral artery (MCA) territory asymmetry indices were calculated., Statistical Tests: Independent Student's t-test to compare the variables from the CCD positive(+) and CCD negative(-) groups and analysis of covariance (ANCOVA) to statistically control the effect of covariates (infarct volume and time since ischemia onset)., Results: CCD was present in 33% of patients. In the MCA territory of the affected hemisphere, BOLD-CVR was significantly more impaired in the CCD(+) group as compared to the CCD(-) group (mean BOLD-CVR ± SD [%BOLD signal/ΔmmHgCO 2 ]: -0.03 ± 0.12 vs. 0.11 ± 0.13, P < 0.05). Moreover, the mean transit time (MTT) (asymmetry index (%) CCD(+) vs. CCD(-): 28 ± 23 vs. 4 ± 11, P < 0.05) and time to peak (TTP) (10 ± 10 vs. 2 ± 5, P < 0.05) in the MCA territory of the affected hemisphere were significantly prolonged, while cerebral blood volume was, on average, increased in the CCD(+) group (25 ± 15 vs. 4 ± 19, P < 0.05)., Data Conclusion: Our findings show that, in patients with symptomatic unilateral anterior circulation stroke, CCD is associated with hemodynamic impairment in the ipsilateral MCA territory, which further supports the concept of a vascular component of CCD., Level of Evidence: 3 TECHNICAL EFFICACY STAGE: 3., (© 2020 International Society for Magnetic Resonance in Medicine.)

Background: Diffuse gliomas exhibit diffuse infiltrative growth, often beyond the magnetic resonance imaging (MRI)-detectable tumor lesion. Within this lesion, hypermetabolism and impaired cerebrovascular reactivity (CVR) are found, but its exact distribution pattern into the peritumoral environment is unknown. Our aim was to better characterize the extent of diffuse glioma tissue infiltration, beyond the visible lesion (ie, beyond the T1-contrast-enhancing lesion and/or T2/FLAIR-defined tumor border), with metabolic positron emission tomography (PET), and functional MRI CVR (blood oxygenation-level-dependent CVR [BOLD-CVR]) mapping., Methods: From a prospective glioma database, 18 subjects (19 datasets) with diffuse glioma ( n = 2 with anaplastic astrocytoma, n = 10 with anaplastic oligodendroglioma, and n = 7 with glioblastoma) underwent a BOLD-CVR and metabolic PET study between February 2016 and September 2019, 7 of them at primary diagnosis and 12 at tumor recurrence. In addition, 19 matched healthy controls underwent an identical BOLD-CVR study. The tumor lesion was defined using high-resolution anatomical MRI. Volumes of interest starting from the tumor lesion outward up to 30 mm were created for a detailed peritumoral PET and BOLD-CVR tissue analysis. Student's t test was used for statistical analysis., Results: Patients with diffuse glioma exhibit impaired BOLD-CVR 12 mm beyond the tumor lesion ( P = .02) with normalization of BOLD-CVR values after 24 mm. Metabolic PET shows a difference between the affected and contralateral hemisphere of 6 mm ( P = .05) with PET values normalization after 12 mm., Conclusion: We demonstrate hypermetabolism and impaired CVR beyond the standard MRI-defined tumor border, suggesting active tumor infiltration in the peritumoral environment., (© The Author(s) 2021. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)

Blood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR) has gained attention in recent years as an effective way to investigate CVR, a measure of the hemodynamic state of the brain, with high spatial and temporal resolution. An association between impaired CVR and diverse pathologies has been observed, especially in ischemic cerebrovascular diseases and brain gliomas. The ability to obtain this information intraoperatively is novel and has not been widely tested. We report our first experience with this intraoperative technique in vascular and oncologic neurosurgical patients, discuss the results of its feasibility, and the possible developments of the intraoperative employment of BOLD-CVR.

Background: Accuracy of lead placement is the key to success in deep brain stimulation (DBS). Precise anatomic stereotactic planning usually is based on stable perioperative anatomy. Pneumocephalus due to intraoperative CSF loss is a common procedure-related phenomenon which could lead to brain shift and targeting inaccuracy. The aim of this study was to evaluate potential risk factors of pneumocephalus in DBS surgery., Methods: We performed a retrospective single-center analysis in patients undergoing bilateral DBS. We quantified the amount of pneumocephalus by postoperative CT scans and corrected the data for accompanying brain atrophy by an MRI-based score. Automated computerized segmentation algorithms from a dedicated software were used. As potential risk factors, we evaluated the impact of trephination size, the number of electrode tracks, length of surgery, intraoperative blood pressure, and brain atrophy., Results: We included 100 consecutive patients that underwent awake DBS with intraoperative neurophysiological testing. Systolic and mean arterial blood pressure showed a substantial impact with an inverse correlation, indicating that lower blood pressure is associated with higher volume of pneumocephalus. Furthermore, the length of surgery was clearly correlated to pneumocephalus., Conclusion: Our analysis identifies intraoperative systolic and mean arterial blood pressure as important risk factors for pneumocephalus in awake stereotactic surgery.

Background: Shunt-dependent hydrocephalus significantly complicates subarachnoid hemorrhage (SAH), and reliable prognosis methods have been sought in recent years to reduce morbidity and costs associated with delayed treatment or neglected onset. Machine learning (ML) defines modern data analysis techniques allowing accurate subject-based risk stratifications. We aimed at developing and testing different ML models to predict shunt-dependent hydrocephalus after aneurysmal SAH., Methods: We consulted electronic records of patients with aneurysmal SAH treated at our institution between January 2013 and March 2019. We selected variables for the models according to the results of the previous works on this topic. We trained and tested four ML algorithms on three datasets: one containing binary variables, one considering variables associated with shunt-dependency after an explorative analysis, and one including all variables. For each model, we calculated AUROC, specificity, sensitivity, accuracy, PPV, and also, on the validation set, the NPV and the Matthews correlation coefficient (ϕ)., Results: Three hundred eighty-six patients were included. Fifty patients (12.9%) developed shunt-dependency after a mean follow-up of 19.7 (± 12.6) months. Complete information was retrieved for 32 variables, used to train the models. The best models were selected based on the performances on the validation set and were achieved with a distributed random forest model considering 21 variables, with a ϕ = 0.59, AUC = 0.88; sensitivity and specificity of 0.73 (C.I.: 0.39-0.94) and 0.92 (C.I.: 0.84-0.97), respectively; PPV = 0.59 (0.38-0.77); and NPV = 0.96 (0.90-0.98). Accuracy was 0.90 (0.82-0.95)., Conclusions: Machine learning prognostic models allow accurate predictions with a large number of variables and a more subject-oriented prognosis. We identified a single best distributed random forest model, with an excellent prognostic capacity (ϕ = 0.58), which could be especially helpful in identifying low-risk patients for shunt-dependency.

Introduction: The presence of peritumorally impaired blood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR) has been unequivocally demonstrated in patients with diffuse glioma, and may have value to better identify tumor infiltration zone. Since BOLD-CVR does not measure hemodynamic changes directly, we performed additional MR perfusion studies to better characterize the peritumoral hemodynamic environment., Methods: Seventeen patients with WHO grade III and IV diffuse glioma underwent high resolution advanced hemodynamic MR imaging including BOLD-CVR and MR perfusion. The obtained multiparametric hemodynamic factors (i.e., regional cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), mean transit time (MTT), time-to-peak (TTP) and BOLD-CVR, were analyzed within 10 concentric expanding 3 mm volumes of interest (VOIs) up to 30 mm from the tumor tissue mask., Results: BOLD-CVR impairment was found within the tumor tissue mask and the peritumoral VOIs up to 21 mm as compared to the contralateral flipped CVR analysis (p<0.05). In the affected hemisphere, we observed positive spatial correlations including all VOIs between BOLD-CVR and rCBV values (r=0.27; p<0.001), rCBF (r=0.42; p<0.001) and a negative correlation between BOLD-CVR and TTP (r=-0.47; p<0.001)., Conclusions: Peritumorally impaired BOLD-CVR is associated with concomitant hemodynamic alterations with severity correlating to tumor volume. The distribution of these multiparametric hemodynamic MRI patterns may be considered for future studies characterizing the hemodynamic peritumoral environment, thereby better identifying the extent of tumor infiltration., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

The clinical significance of ipsilateral thalamic diaschisis (ITD) occurring after stroke is unknown. To characterize ITD, we investigate its hemodynamic, structural, and clinical implications. A single-institution prospective cross-sectional study was conducted using 28 symptomatic cerebrovascular steno-occlusive patients undergoing both BOLD-CVR and Diamox-challenged 15 (O)-H 2 O-PET. Follow-up was at least three months. In addition, 15 age-matched healthy subjects were included. ITD was diagnosed based on a BOLD-CVR thalamic asymmetry index (TAI) > +2 standard deviations from healthy subjects. Cerebral blood flow differences were assessed using a PET-based TAI before and after Diamox challenge. Thalamic volume masks were determined using Freesurfer. Neurological status at symptom onset and after three months was determined with NIHSS and mRS scores. ITD was diagnosed in 15 of 28 (57%) patients. PET-TAI before and after Diamox challenge were increased in patients with ITD, indicating an ipsilateral thalamic blood flow decrease. Patients with ITD exhibited a marked ipsilateral thalamic volume decrease as compared to patients without ITD and healthy subjects. Furthermore, patients with ITD had worse NIHSS and mRS at symptom onset and after three months follow-up, even after adjustment for stroke volume. The presence of ITD is characterized by thalamic volume reduction, reduced thalamic blood flow, and worse neurological performance unrelated to stroke volume.

Background: Lesions arising or abutting in the posterior half of the third ventricle are approached through established routes to avoid damage of essential brain structures. Occasionally, the features of the lesion require rethinking these traditional routes and tailoring the surgical approach to cause fewer debilitating sequelae to the patient. We introduce a modification of previously described transcortical approaches to lesions of the posterior third ventricle. The technique and possible indications are discussed., Methods: Two cases of posterior third ventricle tumors are presented. In both patients, a small posterior fossa and large tentorial veins located along the surgical route, as well as the position of the lesion underneath the internal cerebral veins, encouraged the concept of a novel transoccipital horn approach that was developed to access the tumor with less postoperative deficits., Results: Both lesions were removed with transitory postoperative visual deficits., Conclusions: The transoccipital horn approach is a feasible alternative to other surgical routes to the posterior part of the third ventricle in cases of particularly challenging anatomy and tumor characteristics. It allows reaching the lesion along its major axis, fully exploiting the natural space created by the tumor in its growth and avoiding the internal cerebral veins., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: It is currently unclear if there are subsets of patients undergoing transsphenoidal surgery (TSS) in which intraoperative high-field magnetic resonance imaging (3T-iMRI) is particularly advantageous. We aimed to investigate whether a radiological grading scale predicts the utility of 3T-iMRI in pituitary adenoma (PA) TSS., Methods: From a prospective registry, patients who underwent endoscopic TSS for PA using 3T-iMRI were identified. Adenomas were graded using the Zurich Pituitary Score (ZPS). We assessed improvement after 3T-iMRI in terms of gross total resection (GTR), residual volume (RV), and extent of resection (EOR)., Results: Among 95 patients, rates of conversion to GTR after 3T-iMRI decreased steadily from 33% for grade I to 0% for grade IV adenomas, with a statistically significant conversion rate only for grade I (p = 0.008) and grade II (p < 0.001). All grade I adenomas were completely resected after 3T-iMRI. Median RV change was statistically significant for grades I to III, but not for grade IV (p = 0.625). EOR improvement ranged from a median change of 0.0% (IQR 0.0-4.5%) for grade I to 4.4% (IQR 0.0-9.0%) for grade IV, with a significant improvement only for grades I to III (p < 0.05)., Conclusions: Interestingly, this study shows that clinical utility of 3T-iMRI is highest in the more "simple" adenomas (ZPS grades I-II) than for the more "complex" ones (ZPS grade III-IV). Grade I adenomas are amenable to GTR if 3T-iMRI is implemented. In grade III adenomas, EOR and RV can be improved to clinically relevant levels. Conversely, in grade IV adenomas, 3T-iMRI may be of limited use.

Objective: Although rates of postoperative morbidity and mortality have become relatively low in patients undergoing transnasal transsphenoidal surgery (TSS) for pituitary adenoma, cerebrospinal fluid (CSF) fistulas remain a major driver of postoperative morbidity. Persistent CSF fistulas harbor the potential for headache and meningitis. The aim of this study was to investigate whether neural network-based models can reliably identify patients at high risk for intraoperative CSF leakage., Methods: From a prospective registry, patients who underwent endoscopic TSS for pituitary adenoma were identified. Risk factors for intraoperative CSF leaks were identified using conventional statistical methods. Subsequently, the authors built a prediction model for intraoperative CSF leaks based on deep learning., Results: Intraoperative CSF leaks occurred in 45 (29%) of 154 patients. No risk factors for CSF leaks were identified using conventional statistical methods. The deep neural network-based prediction model classified 88% of patients in the test set correctly, with an area under the curve of 0.84. Sensitivity (83%) and specificity (89%) were high. The positive predictive value was 71%, negative predictive value was 94%, and F1 score was 0.77. High suprasellar Hardy grade, prior surgery, and older age contributed most to the predictions., Conclusions: The authors trained and internally validated a robust deep neural network-based prediction model that identifies patients at high risk for intraoperative CSF. Machine learning algorithms may predict outcomes and adverse events that were previously nearly unpredictable, thus enabling safer and improved patient care and better patient counseling.

Task-evoked Blood-oxygenation-level-dependent (BOLD-fMRI) signal activation is widely used to interrogate eloquence of brain areas. However, data interpretation can be improved, especially in regions with absent BOLD-fMRI signal activation. Absent BOLD-fMRI signal activation may actually represent false-negative activation due to impaired cerebrovascular reactivity (BOLD-CVR) of the vascular bed. The relationship between impaired BOLD-CVR and BOLD-fMRI signal activation may be better studied in healthy subjects where neurovascular coupling is known to be intact. Using a model-based prospective end-tidal carbon dioxide (CO2) targeting algorithm, we performed two controlled 3 tesla BOLD-CVR studies on 17 healthy subjects: 1: at the subjects' individual resting end-tidal CO2 baseline. 2: Around +6.0 mmHg CO2 above the subjects' individual resting baseline. Two BOLD-fMRI finger-tapping experiments were performed at similar normo- and hypercapnic levels. Relative BOLD fMRI signal activation and t-values were calculated for BOLD-CVR and BOLD-fMRI data. For each component of the cerebral motor-network (precentral gyrus, postcentral gyrus, supplementary motor area, cerebellum und fronto-operculum), the correlation between BOLD-CVR and BOLD-fMRI signal changes and t-values was investigated. Finally, a voxel-wise quantitative analysis of the impact of BOLD-CVR on BOLD-fMRI was performed. For the motor-network, the linear correlation coefficient between BOLD-CVR and BOLD-fMRI t-values were significant (p<0.01) and in the range 0.33-0.55, similar to the correlations between the CVR and fMRI Δ%signal (p<0.05; range 0.34-0.60). The linear relationship between CVR and fMRI is challenged by our voxel-wise analysis of Δ%signal and t-value change between normo- and hypercapnia. Our main finding is that BOLD fMRI signal activation maps are markedly dampened in the presence of impaired BOLD-CVR and highlights the importance of a complementary BOLD-CVR assessment in addition to a task-evoked BOLD fMRI to identify brain areas at risk for false-negative BOLD-fMRI signal activation., Competing Interests: The RespirAct is currently a non-clinical research tool approved by Health Canada, assembled, and made available by Thornhill Research Inc. (TRI), a spin-off company from the University Health Network, to research institutions to enable CVR studies. J.A.F. is the Chief Scientist and director of TRI. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Blood oxygenation level-dependent functional MRI cerebrovascular reactivity (BOLD-CVR) is a contemporary technique to assess brain tissue hemodynamic changes after extracranial- intracranial (EC-IC) bypass flow augmentation surgery. The authors conducted a preliminary study to investigate the feasibility and safety of intraoperative 3-T MRI BOLD-CVR after EC-IC bypass flow augmentation surgery. Five consecutive patients selected for EC-IC bypass revascularization underwent an intraoperative BOLD-CVR examination to assess early hemodynamic changes after revascularization and to confirm the safety of this technique. All patients had a normal postoperative course, and none of the patients exhibited complications or radiological alterations related to prolonged anesthesia time. In addition to intraoperative flow measurements of the bypass graft, BOLD-CVR maps added information on the hemodynamic status and changes at the brain tissue level. Intraoperative BOLD-CVR is feasible and safe in patients undergoing EC-IC bypass revascularization. This technique can offer immediate hemodynamic feedback on brain tissue revascularization after bypass flow augmentation surgery.

Purpose: To describe the volumetric changes that the pituitary gland (PG) undergoes during and after transsphenoidal surgery (TSS), and to evaluate if unfolding and/or pruning are related to endocrinological outcome measures., Methods: Retrospective evaluation of data prospectively collected of a cohort of patients undergoing TSS for a pituitary adenoma with the adjunctive use of high field 3 Tesla intraoperative MRI. All patients underwent a full endocrinological workup preoperatively, as well as at 6 weeks and 1 year postoperatively. A decrease in PG volume ≥15% between the intraoperative and 3-month, or between the 3-month and 12-month measurements, was considered early and late pruning, respectively., Results: The PG unfolds significantly during TSS, and subsequently undergoes pruning up until 1 year postoperatively, in most cases returning to the preoperatively measured PG volume. A smaller baseline PG volume predicts intraoperative unfolding. Early pruning of the PG after surgery was associated with new functional deficits. Baseline pituitary compression also correlated to newly occurring deficits after surgery. A larger 1-year pituitary volume was associated with biochemical remission in secreting adenomas., Conclusions: The PG shows dynamic change during and after TSS for pituitary adenoma. Small baseline and 3-month PG volumes, as well as early pruning were independently associated with new deficits. Our findings warrant prospective validation in a larger cohort with higher statistical power.

OBJECTIVEGross-total resection (GTR) is often the primary surgical goal in transsphenoidal surgery for pituitary adenoma. Existing classifications are effective at predicting GTR but are often hampered by limited discriminatory ability in moderate cases and by poor interrater agreement. Deep learning, a subset of machine learning, has recently established itself as highly effective in forecasting medical outcomes. In this pilot study, the authors aimed to evaluate the utility of using deep learning to predict GTR after transsphenoidal surgery for pituitary adenoma.METHODSData from a prospective registry were used. The authors trained a deep neural network to predict GTR from 16 preoperatively available radiological and procedural variables. Class imbalance adjustment, cross-validation, and random dropout were applied to prevent overfitting and ensure robustness of the predictive model. The authors subsequently compared the deep learning model to a conventional logistic regression model and to the Knosp classification as a gold standard.RESULTSOverall, 140 patients who underwent endoscopic transsphenoidal surgery were included. GTR was achieved in 95 patients (68%), with a mean extent of resection of 96.8% ± 10.6%. Intraoperative high-field MRI was used in 116 (83%) procedures. The deep learning model achieved excellent area under the curve (AUC; 0.96), accuracy (91%), sensitivity (94%), and specificity (89%). This represents an improvement in comparison with the Knosp classification (AUC: 0.87, accuracy: 81%, sensitivity: 92%, specificity: 70%) and a statistically significant improvement in comparison with logistic regression (AUC: 0.86, accuracy: 82%, sensitivity: 81%, specificity: 83%) (all p < 0.001).CONCLUSIONSIn this pilot study, the authors demonstrated the utility of applying deep learning to preoperatively predict the likelihood of GTR with excellent performance. Further training and validation in a prospective multicentric cohort will enable the development of an easy-to-use interface for use in clinical practice.

Background: The extent of resection (EOR) is a crucial outcome parameter in transsphenoidal pituitary surgery (TSS), and is linked to endocrinological outcome, postoperative morbidity, and mortality. We aimed to build a robust, quantitative, and easily reproducible imaging score able to predict EOR in TSS., Methods: The ratio (R) between the maximum horizontal adenoma diameter and intercarotid distance at the horizontal C4 segment was used to stratify our patient series in four classes: class I R ≤ 0.75, class II 0.75 < R ≤ 1.25, and class III R ≥ 1.25. Class IV included adenomas which completely encased the internal carotid artery. The resulting score was internally validated for robustness., Results: One hundred sixteen patients were included in the study, of which 96 (83%) for derivation and 20 (17%) for validation. EOR showed significant differences between grades (grade I, 100%; II, 97.9%; III, 94.2%; IV, 87.2%; all P < 0.05). The same applied to residual volume (RV) (grade I, 0 cm 3 ; II, 0.08 cm 3 ; III, 1.11 cm 3 ; IV, 1.63 cm 3 ; all P < 0.05). Differences in gross total resection (GTR) were statistically significant among classes I, II, and III (P < 0.05). The incidence of residual adenoma in the cavernous sinus increased also constantly from grade I up to grade IV although a significant difference was only found between grades III and II (P = 0.004). The score performed equally well in the validation cohort. Inter-observer agreement was high, with intraclass correlation coefficients > 0.89 for measurement of both the horizontal tumor diameter and the ICD among two independent raters (P < 0.001)., Conclusions: The proposed score is a simple and reproducible tool which reliably predicts surgical outcome including EOR, RV, and GTR of pituitary adenoma patients undergoing TSS.

Purpose: Injuries to the internal carotid artery (ICA) are potentially lethal complications in transsphenoidal surgery (TSS) for pituitary lesions. The intercarotid distance (ICD) is thus a major parameter, determining the width of the surgical corridor in TSS. The purpose of the study is to investigate changes in ICD at different levels of the ICA during and after TSS using high definition intraoperative MRI (3T-iMRI)., Methods: Pre-, intra- and 3 months postoperative MRI images of 85 TSS patients were reviewed. ICD was measured at the horizontal (ICDC4h) and vertical (ICDC4v) intracavernous C4 segment as well as at the C6 segment (ICDC6). Association between ICD change at different levels and time points were compared and potential factors predicting ICD reduction were analyzed., Results: ICD decreased intraoperatively at all three segments of ICA by -3% (median decreases: ICDC4h: -0.5 mm, ICDC4v: -0.7 mm ICDC6: -0.4 mm). At 3 months postoperative MRI, ICD reduced by a further -4%, -2% and -4% respectively (median decreases ICDC4h: -0.7, ICDC4v: -0.4 mm, ICDC6: -0.5 mm). Postoperative narrowing in ICD occurred independent of further resection after 3T-iMRI. ICD change correlated between different levels of the ICA indicating a uniform shift perioperatively. Preoperative ICD was significantly associated with the intraoperative reduction in ICDC4v and ICDC6., Conclusions: We have demonstrated a uniform narrowing in ICD at different levels of the ICA during and after TSS adenoma resection. Surgeons should be aware of this change since it determines the width of the surgical corridor and can thus influence the ease of surgery.

Traumatic or amputation neuromas are neoformations developing after damage to a peripheral nerve. They are not proper tumors but rather a reactive process or a frustrated attempt of nerve regeneration. Traumatic neuromas are potentially found in every sensory peripheral nerve and often at the site of past surgical intervention, including orbital surgery. A 29-year-old Northern African migrant presented progressive exophthalmos and progressive loss of acuity in left eye, which had started about 6 months before after a cranio-facial trauma caused by a violent assault. MRI of the orbits showed a massive intra-orbital, intra-conical lesion, clearly compressing and dislocating the optic nerve and extending posteriorly to the orbital apex. Surgery was performed through lateral approach of Kroenlein and led to complete excision of the lesion. Histology revealed fibrotic, adipose and striated muscle tissues, a disordered, non-neoplastic overgrowth of small and large fascicles of nerves, inflammatory infiltrates, and fibrosis with sparse calcifications were diffusely observed in a background of fat, scar and striated muscle tissued. Patient was discharged on the fifth day in good health condition, without deficit of eye motion but without recovery of visual acuity. In conclusion, this case demonstrates that traumatic neuromas may arise in the orbit in patients with minor direct trauma to nerves and without previous surgical treatment.