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The vacuolar proton-translocating ATPase (V-ATPase) is a transmembrane multi-protein complex fundamental in maintaining a normal intracellular pH. In the tumoral contest, its role is crucial since the metabolism underlying carcinogenesis is mainly based on anaerobic glycolytic reactions. Moreover, neoplastic cells use the V-ATPase to extrude chemotherapy drugs into the extra-cellular compartment as a drug resistance mechanism. In glioblastoma (GBM), the most malignant and incurable primary brain tumor, the expression of this pump is upregulated, making it a new possible therapeutic target. In this work, the bafilomycin A1-induced inhibition of V-ATPase in patient-derived glioma stem cell (GSC) lines was evaluated together with temozolomide, the first-line therapy against GBM. In contrast with previous published data, the proposed treatment did not overcome resistance to the standard therapy. In addition, our data showed that nanomolar dosages of bafilomycin A1 led to the blockage of the autophagy process and cellular necrosis, making the drug unusable in models which are more complex. Nevertheless, the increased expression of V-ATPase following bafilomycin A1 suggests a critical role of the proton pump in GBM stem components, encouraging the search for novel strategies to limit its activity in order to circumvent resistance to conventional therapy.

Despite the efforts made in recent decades, glioblastoma is still the deadliest primary brain cancer without cure. The potential role in tumour maintenance and progression of the peritumoural brain zone (PBZ), the apparently normal area surrounding the tumour, has emerged. Little is known about this area due to a lack of common definition and due to difficult sampling related to the functional role of peritumoural healthy brain. The aim of this work was to better characterize the PBZ and to identify genes that may have role in its malignant transformation. Starting from our previous study on the comparison of the genomic profiles of matched tumour core and PBZ biopsies, we selected CDK4 and EXT2 as putative malignant drivers of PBZ. The gene expression analysis confirmed their over-expression in PBZ, similarly to what happens in low-grade glioma and glioblastoma, and CDK4 high levels seem to negatively influence patient overall survival. The prognostic role of CDK4 and EXT2 was further confirmed by analysing the TCGA cohort and bioinformatics prediction on their gene networks and protein–protein interactions. These preliminary data constitute a good premise for future investigations on the possible role of CDK4 and EXT2 in the malignant transformation of PBZ.

Background: The exoscope is a high-definition telescope recently introduced in neurosurgery. In the past few years, several reports have described the advantages and disadvantages of such technology. No studies have compared results of surgery with standard microscope and exoscope in patients with glioblastoma multiforme (GBM). Methods: Our retrospective study encompassed 177 patients operated on for GBM (WHO 2021) between February 2017 and August 2022. A total of 144 patients were operated on with a microscope only and the others with a 3D4K exoscope only. All clinical and radiological data were collected. Progression-free survival (PFS) and overall survival (OS) have been estimated in the two groups and compared by the Cox model adjusting for potential confounders (e.g., sex, age, Karnofsky performance status, gross total resection, MGMT methylated promoter, and operator’s experience). Results: IDH was mutated in 9 (5.2%) patients and MGMT was methylated in 76 (44.4%). Overall, 122 patients received a gross total resection, 14 patients received a subtotal resection, and 41 patients received a partial resection. During follow-up, 139 (73.5%) patients experienced tumor recurrence and 18.7% of them received a second surgery. After truncation to 12 months, the median PFS for patients operated on with the microscope was 8.82 months, while for patients operated on with the exoscope it was >12 months. Instead, the OS was comparable in the two groups. The multivariable Cox model showed that the use of microscope compared to the exoscope was associated with lower progression-free survival (hazard ratio = 3.55, 95%CI = 1.66–7.56, p = 0.001). Conclusions: The exoscope has proven efficacy in terms of surgical resection, which was not different to that of the microscope. Furthermore, patients operated on with the exoscope had a longer PFS. A comparable OS was observed between microscope and exoscope, but further prospective studies with longer follow-up are needed.

Objective: To evaluate the viability of exoscopes in the context of neurosurgical education and compare the use of a 4k3D exoscope to a traditional operative microscope in the execution of a task of anatomic structure identification on a model of cranial approach. Material and methods: A cohort of volunteer residents performed a task of anatomical structure identification with both devices three times across an experimental period of 2 months. We timed the residents’ performances, and the times achieved were analyzed. The volunteers answered two questionnaires concerning their opinions of the two devices. Results: Across tries, execution speed improved for the whole cohort. When using the exoscopes, residents were quicker to identify a single anatomical structure starting from outside the surgical field when deep structures were included in the pool. In all other settings, the two devices did not differ in a statistically significant manner. The volunteers described the exoscope as superior to the microscope in all the aspects the questionnaires inquired about, besides the depth of field perception, which was felt to be better with the microscope. Volunteers furthermore showed overwhelming support for training on different devices and with models of surgical approaches. Conclusion: The exoscope appeared to be non-inferior to the microscope in the execution of a task of timed identification of anatomical structures on a model of cranial approach carried out by our cohort of residents. In the questionnaires, the residents reported the exoscope to be superior to the microscope in eight of nine investigated domains. Further studies are needed to investigate the use of the exoscope in learning of microsurgical skills.

(1) Background: brain metastases (BMs) are the most common neoplasm of the central nervous system; despite the high incidence of this type of tumour, to date there is no universal consensus on the most effective treatment in patients with BMs, even if surgery still plays a primary role. Despite this, the adjunct systems that help to reach the GTR, which are well structured for other tumour forms such as ultrasound and fluorescence systems, are not yet well employed and standardised in surgical practice. The aim of this review is to provide a picture of the current state-of-art of the roles of iOUS and intraoperative fluorescence to better understand their potential roles as surgical tools. (2) Methods: to reach this goal, the PubMed database was searched using the following string as the keyword: (((Brain cerebral metastasis [MeSH Major Topic])OR (brain metastasis, [MeSH Major Topic])) AND ((5-ala, [MeSH Terms]) OR (Aminolevulinicacid [All fields]) OR (fluorescein, [MeSH Terms]) OR (contrast enhanced ultrasound [MeSH Terms])OR ((intraoperative ultrasound. [MeSH Terms]))) AND (english [Filter]) AND ((english [Filter]) AND (2010:2022 [pdat])) AND (english [Filter]). (3) Results: from our research, a total of 661 articles emerged; of these, 57 were selected. 21 of these included BMs generically as a secondary class for comparisons with gliomas, without going deeply into specific details. Therefore, for our purposes, 36 articles were considered. (4) Conclusions: with regard to BMs treatment and their surgical adjuncts, there is still much to be explored. This is mainly related to the heterogeneity of patients, the primary tumour histology and the extent of systemic disease; regardless, surgery plays a paramount role in obtaining a local disease control, and more standardised surgical protocols need to be made, with the aim of optimizing the use of the available surgical adjuncts and in order to increase the rate of GTR.

Background: Neuroimaging differentiation of glioblastoma, primary central nervous system lymphoma (PCNSL) and solitary brain metastasis (BM) remains challenging in specific cases showing similar appearances or atypical features. Overall, advanced MRI protocols have high diagnostic reliability, but their limited worldwide availability, coupled with the overlapping of specific neuroimaging features among tumor subgroups, represent significant drawbacks and entail disparities in the planning and management of these oncological patients. Objective: To evaluate the classification performance metrics of a deep learning algorithm trained on T1-weighted gadolinium-enhanced (T1Gd) MRI scans of glioblastomas, atypical PCNSLs and BMs. Materials and Methods: We enrolled 121 patients (glioblastoma: n=47; PCNSL: n=37; BM: n=37) who had undergone preoperative T1Gd-MRI and histopathological confirmation. Each lesion was segmented, and all ROIs were exported in a DICOM dataset. The patient cohort was then split in a training and hold-out test sets following a 70/30 ratio. A Resnet101 model, a deep neural network (DNN), was trained on the training set and validated on the hold-out test set to differentiate glioblastomas, PCNSLs and BMs on T1Gd-MRI scans. Results: The DNN achieved optimal classification performance in distinguishing PCNSLs (AUC: 0.98; 95%CI: 0.95 - 1.00) and glioblastomas (AUC: 0.90; 95%CI: 0.81 - 0.97) and moderate ability in differentiating BMs (AUC: 0.81; 95%CI: 0.70 - 0.95). This performance may allow clinicians to correctly identify patients eligible for lesion biopsy or surgical resection. Conclusion: We trained and internally validated a deep learning model able to reliably differentiate ambiguous cases of PCNSLs, glioblastoma and BMs by means of T1Gd-MRI. The proposed predictive model may provide a low-cost, easily-accessible and high-speed decision-making support for eligibility to diagnostic brain biopsy or maximal tumor resection in atypical cases.

Diffusion tensor imaging (DTI) allows visualization of the main white matter tracts while intraoperative neurophysiological monitoring (IONM) represents the gold standard for surgical resection of gliomas. In recent years, the use of small craniotomies has gained popularity thanks to neuronavigation and to the low morbidity rates associated with shorter surgical procedures. The aim of this study was to review a series of patients operated for glioma using DTI, IONM, and tumor-targeted craniotomies. The retrospective analysis included patients with supratentorial glioma who met the following inclusion criteria: preoperative DTI, intraoperative IONM, tumor-targeted craniotomy, pre- and postoperative MRI, and complete clinical charts. The DTI was performed on a 3T scanner. The IONM included electroencephalography (EEG), transcranial (TC) and/or cortical motor-evoked potentials (MEP), electrocorticography (ECoG), and direct electrical stimulation (DES). Outcomes included postoperative neurological deficits, volumetric extent of resection (EOR), and overall survival (OS). One hundred and three patients (61 men, 42 women; mean age 54 ± 14 years) were included and presented the following WHO histologies: 65 grade IV, 19 grade III, and 19 grade II gliomas. After 3 months, only three patients had new neurological deficits. The median postoperative volume was 0cc (IQR 3). The median OS for grade IV gliomas was 15 months, while for low-grade gliomas it was not reached. In our experience, a small craniotomy and a tumor resection supported by IONM and DTI permitted to achieve satisfactory results in terms of neurological outcomes, EOR, and OS for glioma patients.

Introduction: Posterior fossa syndrome (PFS) is a set of debilitating complications that can occur after surgery for posterior fossa tumors. This study aimed to assess the preoperative radiological and surgical risk factors for the onset of PFS in a histologically homogeneous population of children with medulloblastoma and compare it to a similar population of young adults. Methods: Included patients underwent posterior fossa surgery for medulloblastoma at 11 Italian neurosurgical wards (2003–2019) and were referred to Fondazione IRCCS Istituto Nazionale dei Tumori in Milan (INT) for postoperative treatments. We collected patients’ pre- and post-operative clinical, surgical and radiological data from the INT charts. To compare the distribution of variables, we used the Mann–Whitney and Fisher tests for continuous and categorical variables, respectively. Results: 136 patients (109 children and 27 young adults) were included in the study. Among children, 29 (27%) developed PFS, and all of them had tumors at midline site with invasion of the fourth ventricle. Radiological evidence of involvement of the right superior (39% versus 12%; p = 0.011) or middle cerebellar peduncles (52% versus 18%; p = 0.002) seemed more common in children who developed PFS. Young adults showed an expected lower incidence of PFS (4 out of 27; 15%), that may be due to anatomical, physiological and oncological elements. Conclusions: This study confirmed some factors known to be associated with PFS onset and shed light on other debated issues. Our findings enhance an already hypothesized role of cerebellar language lateralization. The analysis of a population of young adults may shed more light on the often-neglected existence of PFS in non-pediatric patients.

Background: The aim of this study was to achieve a consensus on the minimum set of outcome measures and predictors to be used in the neurosurgical practice and on the timing of outcome assessment. Methods: A consensus building approach was employed. All neurosurgical departments in Lombardy (Italy) were invited to participate by the Carlo Besta Neurologic Institute IRCCS Foundation. Three workshops were organized during which a multidisciplinary group called Neurosurgical Outcome Network (NEON) was created and the methodology to select outcome measures, predictors, and timing of outcome assessment was established. Eight working groups were created for the different neurosurgical diseases (neuro-oncological, skull base, vascular, traumatic, spinal, peripheral nervous system, malformation, functional) and 8 workshops were organized to identify the outcome measures and predictors specific for each of the neurosurgical diseases based on the experts' clinical practice and the existing literature. Results: A total of 20 neurosurgical departments participated in this study. Specific outcome measures, predictors and the timing of outcome assessment were identified for each of the 8 neurosurgical diseases. Moreover, a list of variables common to all pathologies were identified by the NEON group as further data to be collected. Conclusions: A consensus on the minimum set of outcome measures and predictors and the timing of outcome assessments for 8 neurosurgical diseases was achieved by a group of neurosurgeons of the Lombardy region, called NEON. These sets could be used in future studies for a more homogeneous data collection and as a starting point to reach further agreement also at national and international level.

(1) Background: Neuroimaging differentiation of glioblastoma, primary central nervous system lymphoma (PCNSL) and solitary brain metastasis (BM) represents a diagnostic and therapeutic challenge in neurosurgical practice, expanding the burden of care and exposing patients to additional risks related to further invasive procedures and treatment delays. In addition, atypical cases and overlapping features have not been entirely addressed by modern diagnostic research. The aim of this study was to validate a previously designed and internally validated ResNet101 deep learning model to differentiate glioblastomas, PCNSLs and BMs. (2) Methods: We enrolled 126 patients (glioblastoma: n = 64; PCNSL: n = 27; BM: n = 35) with preoperative T1Gd-MRI scans and histopathological confirmation. Each lesion was segmented, and all regions of interest were exported in a DICOM dataset. A pre-trained ResNet101 deep neural network model implemented in a previous work on 121 patients was externally validated on the current cohort to differentiate glioblastomas, PCNSLs and BMs on T1Gd-MRI scans. (3) Results: The model achieved optimal classification performance in distinguishing PCNSLs (AUC: 0.73; 95%CI: 0.62–0.85), glioblastomas (AUC: 0.78; 95%CI: 0.71–0.87) and moderate to low ability in differentiating BMs (AUC: 0.63; 95%CI: 0.52–0.76). The performance of expert neuro-radiologists on conventional plus advanced MR imaging, assessed by retrospectively reviewing the diagnostic reports of the selected cohort of patients, was found superior in accuracy for BMs (89.69%) and not inferior for PCNSL (82.90%) and glioblastomas (84.09%). (4) Conclusions: We investigated whether the previously published deep learning model was generalizable to an external population recruited at a different institution—this validation confirmed the consistency of the model and laid the groundwork for future clinical applications in brain tumour classification. This artificial intelligence-based model might represe

Introduction: The surgical goal in glioblastoma treatment is the maximal safe resection of the tumor. Currently the lack of consensus on surgical technique opens different approaches. This study describes the “perilesional technique” and its outcomes in terms of the extent of resection, progression free survival and overall survival. Methods: Patients included (n = 40) received a diagnosis of glioblastoma and underwent surgery using the perilesional dissection technique at “San Gerardo Hospital”between 2018 and 2021. The tumor core was progressively isolated using a circumferential movement, healthy brain margins were protected with Cottonoid patties in a “shingles on the roof” fashion, then the tumorwas removed en bloc. Intraoperative ultrasound (iOUS) was used and at least 1 bioptic sample of “healthy” margin of the resection was collected and analyzed. The extent of resection was quantified. Extent of surgical resection (EOR) and progression free survival (PFS)were safety endpoints of the procedure. Results: Thirty-four patients (85%) received a gross total resection(GTR) while 3 (7.5%) patients received a sub-total resection (STR), and 3 (7.5%) a partial resection (PR). The mean post-operative residual volume was 1.44 cm3 (range 0–15.9 cm3).During surgery, a total of 76 margins were collected: 51 (67.1%) were tumor free, 25 (32.9%) were infiltrated. The median PFS was 13.4 months, 15.3 in the GTR group and 9.6 months in the STR-PR group. Conclusions: Perilesional resection is an efficient technique which aims to bring the surgeon to a safe environment, carefully reaching the “healthy” brain before removing the tumoren bloc. This technique can achieve excellent tumor margins, extent of resection, and preservation of apatient’s functions.

Objective: To assess organizational and technical difficulties of neurosurgical procedures during the coronavirus disease 2019 (COVID-19) pandemic and their possible impact on survival and functional outcome and to evaluate virological exposure risk of medical personnel. Methods: Data for all urgent surgical procedures performed in the COVID-19 operating room were prospectively collected. Preoperative and postoperative variables included demographics, pathology, Karnofsky performance status (KPS) and neurological status at admission, type and duration of surgical procedures, length of stay, postoperative KPS and functional outcome comparison, and destination at discharge. We defined 5 classes of pathologies (traumatic, oncological, vascular, infection, hydrocephalus) and 4 surgical categories (burr hole, craniotomy, cerebrospinal fluid shunting, spine surgery). Postoperative SARS-CoV-2 infection was checked in all the operators. Results: We identified 11 traumatic cases (44%), 4 infections (16%), 6 vascular events (24%), 2 hydrocephalus conditions (8%), and 2 oncological cases (8%). Surgical procedures included 11 burr holes (44%), 7 craniotomies (28%), 6 cerebrospinal fluid shunts (24%), and 1 spine surgery (4%). Mean patient age was 57.8 years. The most frequent clinical presentation was coma (44 cases). Mean KPS score at admission was 20 ± 10, mean surgery duration was 85 ± 63 minutes, and mean length of stay was 27 ± 12 days. Mean KPS score at discharge was 35 ± 25. Outcome comparison showed improvement in 16 patients. Four patients died. Mean follow-up was 6 ± 3 months. None of the operators developed postoperative SARS-CoV-2 infection. Conclusions: Standardized protocols are mandatory to guarantee a high standard of care for emergency and urgent surgeries during the COVID-19 pandemic. Personal protective equipment affects maneuverability, dexterity, and duration of interventions without affecting survival and functional outcome.

Objective: This study aims to assess the feasibility and reliability of our endoscopic trans-nasal technique for the repair of cribriform and sellar high-flow cerebrospinal fluid (CSF) leaks. Methods: A comparison between patients suffering from high-flow rhinorrhea and treated through a free grafting endoscopic technique or the “parachute” technique, our nasal packing proposal, was performed. Results: Thirty-three patients were included. The mean age was 52 years (range: 36–68 years). The etiology of the CSF leaks was iatrogenic in 16 cases (48.5%), traumatic in 5 cases (15.2%), spontaneous in 11 cases (33.3%), and related to anterior skull base tumors in 1 case (3%). The bone defect affected the sphenoidal sinus in 20 cases (60.6%), the cribriform plate of the ethmoid in 10 cases (30.3%), and both the sphenoid and ethmoid in 3 cases (9.1%). The mean size of bone defects was 8.5 ± 3.9 mm. The median follow-up was 28 (64) months. A CSF leak recurrence occurred in no cases treated with the parachute technique and in 3 cases that underwent conventional endoscopic treatments. The CSF leak recurrences were associated with 2 iatrogenic and 1 post-traumatic fistula. All the CSF leak recurrences underwent the parachute technique, not showing second recurrences. Conclusions: Our results suggest that the parachute technique is simple, safe, and effective. We recommend it as an alternative treatment to vascular flaps for the treatment of high-flow and recurrent fistulas.

Primary brain tumors are associated with an increased risk of pulmonary embolism (PE), particularly in the early post-operative period. The pathophysiological mechanisms of PE are poorly understood. This study aims to describe prospectively extracellular vesicles (EVs) levels and investigate whether or not their variations allow to identify patients at increased risk of post-operative PE. Consecutive meningioma or glioma patients candidate to tumor resection were included in the study if a pulmonary perfusion scan (Q-scan) performed before surgery ruled out PE. EVs derived from platelets (CD41+) or endothelial cells (CD144+), tissue factor-bearing EVs (CD142+) and their procoagulant subtype (annexin V+) were analyzed by flow cytometry before surgery (T0), within 24 h (T1), two (T2) and seven days (T7) after surgery. Q-scan was repeated at T2. Ninety-three patients with meningioma, 59 with glioma and 76 healthy controls were included in the study. CD142+ and annexin V+/CD142+ EVs were increased at T0 in meningioma and glioma patients compared to healthy controls. Twenty-nine meningioma (32%) and 16 glioma patients (27%) developed PE at T2. EVs levels were similar in meningioma patients with or without PE, whereas annexin V+ and annexin V+/CD142+ EVs were significantly higher at T1 and T2 in glioma patients with PE than in those without. Procoagulant EVs, particularly annexin V+/CD142+, increase after surgery and are more prevalent in glioma patients who developed PE after surgery than in those who did not.

Purpose: The aim of the present study is to assess the predictive value of the suprasellar volume (SSV) of nonfunctioning pituitary adenomas (NFPAs) for visual field (VF) impairment in order to guide clinical decision-making and improve neurosurgical management. Methods: Two independent samples of patients with NFPAs (exploratory population N = 50, testing population N = 98) were included in the present study. In the first phase, we determined the optimal cut-off value of the SSV correlating with VF deficits in the exploratory population. In the second phase, we then studied the accuracy of identified cut-off in predicting a VF deficit in the testing population. Results: In the exploratory population, the optimal cut-off value of the SSV to determine the presence of a VF deficit was 1.5 mL. Sensitivity and specificity of the cut-off were 81.3 and 100%, respectively. The positive predictive value (PPV) and the negative predictive value (NPV) were 100 and 75%, respectively. When we checked the identified cut-off score on the testing population, we found a sensitivity of 71% and a specificity of 100%. The PPV and NPV were 100 and 59.2%, respectively. In six cases with VF defects and SSV inferior to 1.5 mL, the displacement of optic chiasm was in superior position. Conclusion: The SSV may represent an accurate method in routinely clinical practice for predicting VF deficit in patients affected by NFPA.

Introduction: Medulloblastoma is the most common malignant brain tumor in children, but accounts for only 1% of brain cancers in adults. For standard-risk pediatric medulloblastoma, current therapy includes craniospinal irradiation (CSI) at reduced doses (23.4 Gy) associated with chemotherapy. Whereas most same-stage adult patients are still given CSI at 36 Gy, with or without chemotherapy, we report here on our use of reduced-dose CSI associated with chemotherapy for older patients. Methods: We gathered non-metastatic patients over 18 years old (median age 28 years, range 18–48) with minimal or no residual disease after surgery, no negative histological subtypes, treated between 1996–2018 at the Centre Léon Bérard (Lyon) and the INT (Milano). A series of 54 children with similar tumors treated in Milano was used for comparison. Results: Forty-four adults were considered (median follow-up 101 months): 36 had 23.4 Gy of CSI, and 8 had 30.6 Gy, plus a boost to the posterior fossa/tumor bed; 43 had chemotherapy as all 54 children, who had a median 83-month follow-up. The PFS and OS were 82.2 ± 6.1% and 89 ± 5.2% at 5 years, and 78.5 ± 6.9% and 75.2 ± 7.8% at ten, not significantly different from those of the children. CSI doses higher than 23.4 Gy did not influence PFS. Female adult patients tended to have a better outcome than males. Conclusion: The results obtained in our combined series are comparable with, or even better than those obtained after high CSI doses, underscoring the need to reconsider this treatment in adults.

Purpose: There is no consensus in the literature about the impact of hydrocephalus on clinical course and overall survival of diffuse intrinsic pontine gliomas (DIPG) patients as well as about its specific treatment. Authors reviewed a series of DIPG patients to investigate factors related to the onset of hydrocephalus, its treatment, and its impact on clinical course and prognosis. Methods: A retrospective observational study was performed enrolling pediatric patients affected by DIPG from 2008 to 2018. Clinical and radiological charts were reviewed to find patients’ demographic, pathologic and radiologic features in hydrocephalic and non-hydrocephalic patients. In the hydrocephalus cohort, treatment strategy and its effectiveness and complications were analyzed. Results: Ninety-four pediatric patients were enrolled in the study. Patients who developed hydrocephalus showed significantly lesser maximum axial tumor areas than patients without hydrocephalus (respectively 6.5 cm2 vs 16.45 cm2, p < 0.005). Hydrocephalus developed in 33 patients (35%) with an onset interval of 5.24 ± 1.21 months (range 3.2–7.3). The majority of hydrocephalic patients (28 cases, 90%) were treated by ventriculoperitoneal shunt, the remaining 3 patients being treated by endoscopic third ventriculostomy. Mean overall survival was 16.6 months ± 20 months without significative difference between the groups. Conclusion: The onset of hydrocephalus occurs in the first moths of the disease story and found a negative correlation with tumor maximal axial diameter. Early treatment of hydrocephalus presents a very low complications rate with satisfying clinical outcome, as it allows the patients to continue the neurooncological therapies being a part of the treatment armamentarium instead of a palliative solution.

Personalized medicine (PM) aims to optimize patient management, taking into account the individual traits of each patient. The main purpose of PM is to obtain the best response, improving health care and lowering costs. Extending traditional approaches, PM introduces novel patient-specific paradigms from diagnosis to treatment, with greater precision. In neuro-oncology, the concept of PM is well established. Indeed, every neurosurgical intervention for brain tumors has always been highly personalized. In recent years, PM has been introduced in neuro-oncology also to design and prescribe specific therapies for the patient and the patient's tumor. The huge advances in basic and translational research in the fields of genetics, molecular and cellular biology, transcriptomics, proteomics, and metabolomics have led to the introduction of PM into clinical practice. The identification of a patient's individual variation map may allow to design selected therapeutic protocols that ensure successful outcomes and minimize harmful side effects. Thus, clinicians can switch from the “one-size-fits-all” approach to PM, ensuring better patient care and high safety margin. Here, we review emerging trends and the current literature about the development of PM in neuro-oncology, considering the positive impact of innovative advanced researches conducted by a neurosurgical laboratory.

Background: First-line therapy of Cushing disease (CD) is transsphenoidal surgery (TSS) aimed to obtain a complete removal of the pituitary adenoma and remission of disease. Purpose: To analyse the surgical outcome of patients with CD who underwent TSS in our Centre. Methods: Retrospective analysis on patients with CD who underwent TSS between 1990 and 2016. Results: We analysed 102 TSS that included: 84 first TSS and 18 second and third TSS. The overall remission rate after surgery was 76.5%, with a significant higher percentage of remitted patients after the first TSS compared to the subsequent TSS (82% vs 50%, p = 0.014). The remission after the first TSS was significantly higher when performed by a dedicated surgical team (DST) (89.8% vs 71% p = 0.04) and when the immunohistochemical examination confirmed the adrenocorticotropic adenoma (87% vs 55%, p = 0.04). Neuroradiological findings influenced the surgical outcome in a non-significant manner. Post-TSS complications were reported in 32 patients, with no significant variation when TSS was performed by DST. In case of reintervention, remission of disease was obtained in 72.7% of microadenoma, while no remitted patients were observed in case of macroadenomas. The DST did not significantly improve the outcome. Conclusion: Cushing disease is characterized by a broad spectrum of neuroradiological presentation. Despite the availability of a DST make the TSS a safe and effective first-line treatment among all these patients, a precise pre-treatment evaluation is needed in order to define the aim of neurosurgery and to schedule the management of recurrent disease.

Venous thromboembolism (VTE) is a common complication of cancer that severely increases morbidity and mortality. Patients with intracranial tumors are more likely to develop VTE than patients with cancers at other sites. Conversely, limited tools exist to identify patients with high thrombotic risk. Upon activation, neutrophils release their content through different mechanisms triggering thrombosis. We explored the ability of microRNAs (miRNAs) and plasma markers of neutrophil activation measured before surgery to predict the risk of early post-surgical pulmonary embolism (PE) in glioma and meningioma patients. We recruited and prospectively followed 50 patients with glioma and 50 with meningioma, 34% of whom in each group developed an early objectively-diagnosed post-surgical PE. We measured miRNA expression and neutrophil markers (cell-free DNA, nucleosomes, calprotectin and myeloperoxidase) before surgery. In glioma patients, we adjusted and validated a predictive model for post-surgical PE with 6 miRNAs: miR-363-3p, miR-93-3p, miR-22-5p, miR-451a, miR-222-3p and miR-140-3p (AUC = 0.78; 95% Confidence Interval (CI) [0.63, 0.94]) and another with cfDNA and myeloperoxidase as predictors (AUC = 0.71; 95%CI [0.52, 0.90]). Furthermore, we combined both types of markers and obtained a model with myeloperoxidase and miR-140-3p as predictors (AUC = 0.79; 95%CI [0.64, 0.94]). In meningioma patients we fitted and validated a predictive model with 6 miRNAs: miR-29a-3p, miR-660-5p, miR-331-3p, miR-126-5p, miR-23a-3p and miR-23b-3p (AUC = 0.69; 95%CI [0.52, 0.87]). All our models outperformed the Khorana score. This is the first study that analyzes the capability of plasma miRNAs and neutrophil activation markers to predict early post-surgical PE in glioma and meningioma patients. The estimation of the thrombotic risk before surgery may promote a tailored thromboprophylaxis in a selected group of high-risk patients, in order to minimize the incidence of PE and avoid bleeding

Background: Patients affected by a high-grade glioma (HGG) have a poor prognosis with a median survival of 12–16 months. Such poor prognosis affects the perception of the remaining life by patients and the neuropsychological status can strongly affect every-day functioning of these patients. Monitoring changes of neuropsychological functioning (NPF) overtime may provide better clinical information and optimize the neuro-oncological management. The aims of our work were (1) to investigate the feasibility of a complex neuropsychological battery in HGG patients before and during follow-up after surgery; (2) to study the neuropsychological profile of patients affected by HGGs and their relation with the disease status (relapse/death) across time after surgery. Methods: One hundred two patients who received surgery for HGG between 2011 and 2017 were studied. All clinical data were prospectively recorded. NPF was assessed during the neuro-oncological follow-up through the Milano-Bicocca Battery (MIBIB). Statistical analysis was performed on the neuropsychological results of the tests administered. Results: First, MIBIB proved to be suitable for patients with HGG tumors before and after surgery, and during long-term follow-up; it also showed a cluster structure representative of the principal cognitive domains. Second, we found a steep decline in the neuropsychological profile before death and/or tumor relapse for the 52% of the neuropsychological tests administered. Conclusion: Complex neuropsychological batteries can be administered to HGG patients before and during follow-up after surgery. There is a correlation between neuropsychological deterioration and tumor relapse and/or death, which may reflect a progressive damage to cognitive functions due to tumor infiltration and progression.

Recently, the emergence of the three-dimensional (3D) exoscope has proven to be a viable alternative to the operative microscope (OM) as a novel workhorse of microneurosurgical procedures. Through its current iteration, the 3D exoscope has been demonstrated to be at least equivalent to the operative microscope in terms of surgical outcomes in many settings. With its superior ergonomics and simplicity of use, the 3D exoscope has been shown in multiple studies to be a powerful visualizing tool during surgical procedures. Moreover, the exoscopic systems, through their current iterations and by means of a high-resolution 3D monitor and 3D glasses, have allowed all participants present in the operative room to attain an unprecedented level of intraoperative visualization of anatomical structures and surgical maneuvers which are traditionally available only to the first operator. Although long-term data are still lacking regarding its future as a replacement of the OM, the 3D exoscope has revealed itself as an intense subject of discussion in neurosurgery regarding its implication for surgical education, especially for residents and junior neurosurgeons. This article is a review of the current state of the literature on the role of the exoscope in surgical education, underlining its strength as a learning tool and its potential future implications in terms of surgical education.

Introduction: Intradiploic pseudomeningoceles, also called intradiploic cerebrospinal fluid (CSF) fistulas, are abnormal CSF collection between the two bony tables of the calvaria resulting from post-surgical CSF leakage. To date, only six cases of intradiploic pseudomeningocele have been reported, all occurring in the occipital area. In this paper, we report the seventh case of late-onset occipital intradiploic pseudomeningocele (OIP) occurring in a young female patient who underwent surgery for the removal of a cerebellar pilocytic astrocytoma. At this regard, we also review the literature on the few recognized cases of OIP. Case presentation: The case of an 18-year-old female patient known to our institute for an operation 12 years earlier to remove a pilocytic astrocytoma is illustrated. At admission the patient complained only of occasional orthostatic headache. Brain imaging demonstrated a pseudomeningocele extended intradiploically from the occipital squama to the condylar and clivus regions, thinning both occipital bone tables and dilating the CSF-filled diploe. Watertight duroplasty and cranioplasty were effectively performed. Conclusion: Pediatric patients undergoing posterior cranial fossa craniotomy/craniectomy may postoperatively develop OIP. In this setting, treatment of any dural CSF fistula should be considered because of the risk of progressive extension and bone erosion.

Introduction: Cervicomedullary gliomas (CMGs) are usually low-grade tumors often found in the pediatric age. Histological findings, treatments, and classification have been much the same for 40 years, although histological and molecular classifications have largely been developed for other pediatric CNS tumors. The management and treatment of pediatric CMG are still conducted by many authors according to their anatomical location and characteristics, independently from histology. Methods: We conducted a literature review in PubMed (Medline) to identify relevant contributions about pediatric CMG published until December 31, 2021. We also analyzed a series of 10 patients with CMG treated from 2006 to 2021 at IRCCS Istituto Nazionale dei Tumori. The aim of the present review was to see whether and how the diagnosis, treatment, and classification of CMGs in children have developed over time, especially in the context of molecular advancements, and to analyze our single-center experience in the last 15 years. Results: Thirty articles have been included in the review. Articles have been divided into two historical periods (1981-2000 and 2001-2021) and data from different series were analyzed to see how much the management and treatment of pediatric CMG have changed during years. Analysis of our series of 10 patients affected by CMG was also performed to compare it with the literature. Discussion: Management and classification of CMG in children have not dramatically changed during years. However, new insight from molecular diagnostics and target therapies and the development of radiological, neurophysiological, and radiotherapy techniques have updated treatment modalities in the last 20 years. Treatment modalities and their innovations have been reviewed and discussed. Further studies are needed to standardize and customize treatment protocols for these tumors.

Background: Chronic subdural hematoma (CSDH) is one of the most common neurosurgical diseases that affect elderly and fragile patients and as a consequence, management can be challenging. Surgery represents the standard treatment; however, alternative options are under investigation. Middle meningeal artery (MMA) embolization is considered a minimally invasive treatment although with poor evidence. In this review, we tried to summarize the findings about MMA embolization as a treatment for a CSDH to provide a useful guidance for clinical practice and for future speculative aspects. Methods: Literature review on PubMed until March 2021 was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement. We conducted a research on PubMed with a various combinations of the keywords "CSDH"and "middle meningeal artery"and "embolization,""refractory subdural hematoma,"and then we reviewed the references of the relevant studies as additional source of eligible articles. Results: Among the 35 studies eligible for this review, 22 were case series, 11 were case reports, one was a technical note, and 1 was a randomized trial. A total of 746 patients were found in the literature. Failure rate of MMA embolization was between 3.9 and 8.9% of the cases according the indication to treat CSDH (upfront vs. after surgery). Conclusion: The global impression deriving from the data available and the literature is that MMA embolization is a safe procedure with very low complications and with a low failure rate, both when associated with surgery or in case of a standalone treatment.

Background and purposeThe aim of this study was to define the prevalence and characteristics of peri-electrode edema in a prospective cohort of patients undergoing deep brain stimulation (DBS) surgery and to correlate it with clinical findings. MethodsWe performed brain magnetic resonance imaging (MRI) between 7 and 20days after surgery in 19 consecutive patients undergoing DBS surgery for Parkinson's disease. The T2-weighted hyperintensity surrounding DBS leads was characterized and quantified. Any evidence of bleeding around the leads was also evaluated. Clinical and follow-up data were recorded. In a subgroup of patients, a follow-up MRI was performed 3-6weeks after surgery. We also retrospectively reviewed the post-operative computed tomography scans of patients who underwent DBS at our center since 2013. ResultsMagnetic resonance imaging showed a peri-lead edematous reaction in all (100%) patients, which was unilateral in three patients (15.8%). In six patients (31.6%), we detected minor peri-lead hemorrhage. Edema completely resolved in eight out of 11 patients with a follow-up MRI and was markedly reduced in the others. Most patients were asymptomatic but six (31.6%) manifested various degrees of confusional state without motor symptoms. We found no significant correlation between edema volume, distribution and any clinical feature, including new post-operative neurological symptoms. The retrospective computed tomography analysis showed that peri-electrode hypodensity consistent with edema is absent at early post-operative imaging but is common at scans performed >3days after surgery. ConclusionsPeri-electrode edema is a common, transient reaction to DBS lead placement and a convincing relation between edema and post-operative clinical status is lacking.

Background: Idiopathic intracranial hypertension (IIH), also known as pseudotumour cerebri syndrome (PTCS), is characterized by the presence of signs and symptoms of raised intracranial pressure without evidence of any intracranial structural cause and with normal cerebrospinal fluid microscopy and biochemistry. Obesity, various systemic diseases and endocrine conditions, and a number of medications are known to be risk factors for PTCS. The medications commonly associated with PTCS are amiodarone, antibiotics, corticosteroids, cyclosporine, growth hormone, oral contraceptives, vitamin A analogues, lithium, phenytoin, NSAIDs, leuprolide acetate, and some neuroleptic drugs. In relation to antibiotics, quinolones may cause intracranial hypertension, and most reported cases of quinolone-induced intracranial hypertension were associated with nalidixic acid, ciprofloxacin, ofloxacin, or pefloxacin. Literature reports of levofloxacin-induced PTCS are rare. Some authors recently hypothesized that Mycoplasma pneumoniae may trigger PTCS. Case presentation: We report on a 14-year-old overweight White Italian boy who suffered headache, diplopia, and severe bilateral papilloedema after a Mycoplasma pneumoniae infection, exacerbated on levofloxacin intake. A spontaneous improvement in headache and a reduction in diplopia was seen during hospitalisation. Oral acetazolamide therapy led to the regression of papilloedema in about five months. No permanent eye damage has been observed in our patient to date. Conclusions: PTCS pathophysiology may be multifactorial and its specific features and severity may be a consequence of both constitutional and acquired factors interacting synergistically. It may be useful for paediatricians to know that some antibiotics may have the potential to precipitate PTCS in patients who already have an increased CSF pressure due to a transitory imbalanced CSF circulation caused by infections such as Mycoplasma pneumoniae, with headache being the first an

OBJECTIVE Recent trials have shown the safety and benefits of fetoscopic treatment of myelomeningocele (MMC). The authors' aim was to report their preliminary results of prenatal fetoscopic treatment of MMC using a biocellulose patch, focusing on neurological outcomes, fetal and maternal complications, neonatal CSF leakage, postnatal hydrocephalus, and radiological outcomes. METHODS Preoperative assessment included clinical examination, ultrasound imaging, and MRI of the fetus. Patients underwent purely fetoscopic in utero MMC repair, followed by postoperative in utero and postnatal MRI. All participants received multidisciplinary follow-up. RESULTS Five pregnant women carrying fetuses affected by MMC signed informed consent for the fetoscopic treatment of the defect. The mean MMC size was 30.4 mm (range 19-49 mm). Defect locations were L1 (2 cases), L5 (2 cases), and L4 (1 case). Hindbrain herniation and ventriculomegaly were documented in all cases. The mean gestational age at surgery was 28.2 weeks (range 27.8-28.8 weeks). Fetoscopic repair was performed in all cases. The mean gestational age at delivery was 33.9 weeks (range 29.3-37.4 weeks). After surgery, reversal of hindbrain herniation was documented in all cases. Three newborns developed signs of hydrocephalus requiring CSF diversion. Neurological outcomes in terms of motor level were favorable in all cases, but a premature newborn died due to CSF infection and sepsis. CONCLUSIONS The authors' preliminary results suggest that fetoscopic treatment of MMC is feasible, reproducible, and safe for mothers and their babies. Neurological outcomes were favorable and similar to those in the available literature. As known, prematurity was the greatest complication.

Medulloblastoma and central nervous system (CNS) germ cell tumors are very rare in adults, while they account for 25% and 5% of brain tumors in children, respectively (Pastore et al. Eur J Cancer 42:2064–208, 2006). Pediatric experiences, mostly from randomized and controlled clinical trials, have led to different tailored treatments, based on various risk factors, including histology, and extent of disease. For medulloblastoma, biological features have recently emerged that enable therapies to be scaled down in some cases, or pursued more aggressively in the event of chromosomal and/or genetic alterations (Massimino et al. Crit Rev Oncol Hematol 105:35–51, 2016). Such refinements are still impossible for adult patients due to the lack of similar clinical trials that might provide the same or a different understanding regarding patients’ prognosis, long-term survival, quality of life, and acute and late toxicities. This review aims to contribute to the debate on the treatment of adults with these two diseases and promote the creation of broad-based, national and international trials to advance our knowledge in this area and to share the skills between pediatric and adult oncologists as adolescent and young adults (AYA) brain tumor national boards are currently requiring.

Background: For a long time, surgery of insular gliomas was considered at high risk for postoperative cognitive deficits, but recent studies highlighted the feasibility of the surgical approach. The aims of our study were to investigate the presence of language impairment before and after surgery and the relationship between language impairment and tumor volume preoperatively and extent of resection (EOR) 3 months after surgery. Methods: Thirty-five patients with insular gliomas underwent an extensive language assessment before and few days after surgery, and after 3 months. Intraoperative neurophysiological monitoring (IOM) and brain mapping with direct electrical stimulation (DES) were used in all the cases; 8 patients underwent awake craniotomy. Statistical analysis was performed on the language tests administered. Results: Patients with pure left insular lesion showed language impairment before and after surgery. Overall, patients with a left lesion showed a drop of performance after surgery followed by a partial recovery. Moreover, when the tumor involved the insula and adjacent networks, we observed a more severe deficit. No correlations were found between tumor volume, EOR, and language impairment. Conclusions: Left insular lobe is an important hub in language networks; its involvement determines pre- and postsurgical deficits, together with the involvement of white matter connections. Tumor volume and EOR are not risk factors per se directly related to language functioning. Surgery of insular gliomas is possible with a pre- and intraoperative extensive study of the patient with IOM and awake surgery, and encouraged by the trend of cognitive recovery highlighted.

Background: Constructional apraxia (CA) is a neuropsychological impairment of either basic perceptual and motor abilities or executive functions, in the absence of any kind of motor or perceptual deficit. Considering patients with focal brain tumors, CA is common in left or right parietal and parieto-occipital lesions. In neuropsychology, the Rey-Osterrieth Complex Figure Test (ROCFT; or parallel forms) is commonly used for the assessment of CA. This study stems from a clinical observation of a difficulty with CA tests for the majority of older neurosurgical patients without occipitoparietal lesions. Methods: Patients were tested at 3 points: before surgery, 3 months after surgery, and 12 months after surgery. Thirty patients (15 meningiomas and 15 glioblastomas) were studied retrospectively. Results: Older patients with focal brain lesions, regardless of the nature of the tumor, performed poorly at CA tests. More than 50% of patients obtained pathologic results at all 3 times considered. Conclusions: Our findings suggest that as CA complex tests involve multiple domains, poor results in copy task may reflect a global cognitive deficit of older patients with tumors, without a specific constructional praxis deficit. CA complex tests (such as the ROCFT) do not give significant informations about visuo-constructional abilities.

Background: The optic radiation (OR) is a white matter bundle with a very complex anatomy. Its anterior component bends sharply around the tip of the temporal horn, forming the Meyer's loop (ML), the sparing of which during surgery is crucial to preserve visual function. Defining its exact anatomy and accurately identifying its position remain challenging, even with diffusion tensor imaging (DTI) tractography and the most refined tracking procedure. We have developed an alternative tracking technique to detect the ML position. Methods: We performed DTI studies in 26 patients undergoing resection of a temporo-parieto-occipital lesion. We then reconstructed the ORs of each patient using 2 techniques (the first developed by our team, the other taken from the literature), using the same tracking software and parameters. We evaluated the accuracy of each technique measuring 3 distances that define the ML position. We created 5 data groups and compared the 2 techniques. Finally, we compared our results with the results from 8 anatomic dissection studies and other tractographic studies. Results: Our findings show that our technique allows a more accurate definition of the ML position. We found a statistically significant (P < 0.05) difference for all the distances between the 2 techniques; our results resemble those obtained in dissection studies. Our technique is also easy to perform and repeatable. Conclusions: Our tracking technique may be of marked interest for the evaluation and anatomic definition of the ML position, particularly for neurosurgeons approaching the anterior temporal region.

Circulating platelets (PLTs) are able to affect glioblastoma (GBM) microenvironment by supplying oncopromoter and pro-angiogenic factors. Among these mediators, sphingosine-1-phophate (S1P) has emerged as a potent bioactive lipid enhancing cell proliferation and survival. Here, we investigated the effect of “tumor education”, characterizing PLTs from GBM patients in terms of activation state, protein content, and pro-angiogenic potential. PLTs from healthy donors (HD-PLTs) and GBM patients (GBM-PLTs) were collected, activated, and analyzed by flow cytometry, immunofluorescence, and Western blotting. To assess the pro-angiogenic contribution of GBM-PLTs, a functional cord formation assay was performed on GBM endothelial cells (GECs) with PLT-releasate. GBM-PLTs expressed higher positivity for P-selectin compared to HD-PLTs, both in basal conditions and after stimulation with adenosine triphosphate (ADP) and thrombin receptor activating peptide (TRAP). PLTs showed higher expression of VEGFR-1, VEGFR-2, VWF, S1P, S1PR1, SphK1, and SPNS. Interestingly, increased concentrations of VEGF and its receptors VEGFR1 and VEGFR2, VWF, and S1P were found in GBM-PLT-releasate with respect to HD-PLTs. Finally, GBM-PLT-releasate showed a pro-angiogenic effect on GECs, increasing the vascular network’s complexity. Overall, our results demonstrated the contribution of PLTs to GBM angiogenesis and aggressiveness, advancing the potential of an anti-PLT therapy and the usefulness of PLT cargo as predictive and monitoring biomarkers.

Li-Fraumeni syndrome (LFS) is an autosomal dominant disorder caused by mutations in the TP53 gene, predisposing to a wide spectrum of early-onset cancers, including brain tumors. In medulloblastoma patients, the role of TP53 has been extensively investigated, though the prevalence of de novo mutations has not been addressed. We characterized TP53 mutations in a monocentric cohort of consecutive Sonic Hedgehog (SHH)-activated medulloblastoma patients. Germline testing was offered based on tumor p53 immunostaining positivity. Among 24 patients, three (12.5%) showed tumor p53 overexpression, of whom two consented to undergo germline testing and resulted as carriers of TP53 mutations. In the first case, family history was uneventful and the mutation was not found in either of the parents. The second patient, with a family history suggestive of LFS, unexpectedly resulted as a carrier of the mosaic mutation c.742=/C>T p.(Arg248=/Trp). The allele frequency was 26% in normal tissues and 42–77% in tumor specimens. Loss of heterozygosity (LOH) in the tumor was also confirmed. Notably, the mosaic case has been in complete remission for more than one year, while the first patient, as most TP53-mutated medulloblastoma cases from other cohorts, showed a severe and rapidly progressive disease. Our study reported the first TP53 mosaic mutation in medulloblastoma patients and confirmed the importance of germline testing in p53 overexpressed SHH-medulloblastoma, regardless of family history.

High grade gliomas (HGG) are tumors with a rapidly progressive course and the standard of care consists of surgery and chemo-radiotherapy. Elderly patients with HGG usually have a worse prognosis due to their comorbidities and difficulties in accessing or completing adjuvant treatments. The purpose of our study was to assess the influence of pre-operative factors (MMSE, age, sex, KPS, tumor volume) on the post-operative access to chemo-radiotherapy in the elderly population. In addition, the influence of the access to adjuvant therapies on overall survival (OS) was assessed. We retrospectively reviewed our consecutive case series of 117 elderly patients (≥65 years) with HGG treated in our Institution. All the clinical records regarding age, sex, tumor location, MMSE, KPS, access to adjuvant treatments and OS were analyzed. 72 males and 45 females with a median age of 71 years were analyzed. Adjuvant therapies were considered; concomitant chemo-radiotherapy with standard radiotherapy or hypofractionated radiation regimen. 84 patients had access to adjuvant therapies. Access to therapies was associated with a median age of 71(range 66–80) years, a median MMSE of 26(range 5–30), and a median tumor volume of 24 cm3(range 1–140). The median OS was 13 months for patients who had access to adjuvant therapies and 5 months for patients who did not. In the elderly patients with HGG, the MMSE, age and tumor volume were predictive of post-surgery access to adjuvant treatments. OS was significantly longer in elderly patients with HGG who had access to post-surgery chemo-radiotherapy.

OBJECTIVE: Adaptive deep brain stimulation (aDBS) controlled by local field potentials (LFPs) is considered a promising treatment for advanced Parkinson's disease (PD). The clinical research investigating aDBS functioning is performed using external deep brain stimulation (DBS) systems that require LFP recording through the temporary externalization of DBS leads. Although research examining LFP was first undertaken more than 20 years ago, only a few studies concern lead externalization and LFP recording safety. In the present retrospective study, we assessed the risk of infection related to these procedures. METHODS: A total of 105 patients with PD who underwent DBS surgery and lead externalization at our hospital from 2002 to 2014 were included in the present study. The medical records were used to collect clinical data and information concerning surgical site infections. We assessed the infection incidence in our cohort and the risk of infection related to the LFP recording procedure. RESULTS: The incidence of infections in patients who underwent lead externalization was 2.8%, which was consistent with the postoperative infectious risk reported in the literature (Wilcoxon signed rank test; P > 0.05). Moreover, the LFP recording procedure did not significantly increase the infection risk (LFP recordings vs. no LFP recordings: 2.5% vs. 4.2%; Fisher exact test; P > 0.05). CONCLUSIONS: DBS lead externalization and LFP recording are safe and do not increase the postoperative infection risk in patients with PD who undergo DBS surgery. Our retrospective study supported further clinical research in the field of LFP-based aDBS.