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Introduction: Thalamic gliomas pose a particular therapeutic challenge as complete resection is rarely achieved due to the deep and eloquent location. Laser interstitial thermal therapy (LITT) may provide a valuable management option for deep-seated gliomas that are not accessible with open surgery. Case Presentation: A 57-year-old woman presented with a rapidly progressive large thalamic glioblastoma. Opting for full ablation, we selected a challenging trajectory to maximize the possibility of full ablation. At 2.4 cm in diameter, the tumour was larger than recommended for LITT; nevertheless, three laser ablations along a single trajectory resulted in macroscopic ablation without complications. Adjuvant radio-chemotherapy was started soon after surgery without radiological recurrence 1.5 years after the initial surgery. Conclusion: This case demonstrates the potential when thalamic tumours are managed with timely LITT treatment and meticulous trajectory planning. Moreover, it highlights the need for close interdisciplinary management with neurosurgeons, neuropathologists, neuroradiologists, and neurooncologists. [ABSTRACT FROM AUTHOR]

Recent studies have emphasized the complex interplay between neurological and psychiatric symptoms in patients with brain tumors. These manifestations range from cognitive dysfunction and personality changes to unusual psychiatric symptoms like mood disorders and anorexia, challenging traditional diagnostic approaches. This review synthesizes findings from four key studies, highlighting the importance of considering brain tumors in differential diagnoses of psychiatric and neurological presentations. [ABSTRACT FROM AUTHOR]

Abstract Background There are few articles about the surgical techniques of thalamic glioma and the lesions in the basal ganglia area. According to three existing cases and the literature review (Twelve articles were summarized which mainly described the surgical techniques), we discuss the surgical characteristics of lesions of the thalamus and basal ganglia area and summarize the relevant surgical skills. Case presentation Of the three cases, two were thalamic gliomas and one was brain abscess in basal ganglia. According to the three-dimensional concept of the “Four Walls, Two Poles”, lesions of the thalamus and basal ganglia were surgically removed, and the operative effect was analysed by relevant surgical techniques. Surgical resection of the lesions of the thalamus and basal ganglia area according to the three-dimensional concept of the “Four Walls, Two Poles” has achieved good surgical results. Relevant surgical techniques, such as the use of retractors, the use of aspirators, the choice of surgical approaches, and the haemostasis strategy, also played an important role in the operation process. Conclusions In the presented three cases the three-dimensional concept of the “Four Walls, Two Poles” allowed for safe surgical resection of lesions of the thalamus and basal ganglia.

Pediatric high-grade gliomas (pHGGs) encompass a heterogeneous group of tumors. Three main molecular types (H3.3 mutant, IDH mutant, and H3.3/IDH wild-type) and a number of subtypes have been identified. We provide an overview of pHGGs and present a mono-institutional series. We studied eleven non-related pHGG samples through a combined approach of routine diagnostic tools and a gene panel. TP53 and H3F3A were the most mutated genes (six patients each, 54%). The third most mutated gene was EGFR (three patients, 27%), followed by PDGFRA and PTEN (two patients each, 18%). Variants in the EZHIP, MSH2, IDH1, IDH2, TERT, HRAS, NF1, BRAF, ATRX, and PIK3CA genes were relatively infrequent (one patient each, 9%). In one case, gene panel analysis documented the presence of a pathogenic IDH2 variant (c.419G>A, p.Arg140Gln) never described in gliomas. More than one-third of patients carry a variant in a gene associated with tumor-predisposing syndromes. The absence of constitutional DNA did not allow us to identify their constitutional origin. [ABSTRACT FROM AUTHOR]

Introduction: Diffuse midline glioma (DMG) is a relatively new entity which was introduced in the fourth edition of the WHO classification of CNS tumours in 2016 and later underwent revision in 2021. It is an infiltrative glioma arising from midline structures, viz., thalamus, spine, and brainstem. Current literature on DMG is based majorly on brainstem lesions, and DMGs arising elsewhere remain unexplored. In our study, we have discussed our experience with thalamic DMGs., Methodology: This is a retrospective observational study of all patients with histopathologically proven DMG H3K27M altered, arising in the thalamus from 2018 to 2022. Clinical, neuroimaging, and pathology were re-reviewed, and prognostic factors for 3 months, 6 months, and overall survival (OS) were analyzed for all patients., Results: There were 89 patients- 64 adults and 25 pediatric patients with thalamic DMG. The median age at presentation was 24 years. Raised ICP followed by limb weakness were the most common presenting complaints. Stereotactic biopsy was performed in 64 (71.9 %) patients and surgical decompression in 25 (28.1 %) patients. CSF diversion was required in 53 (59.6 %) patients. Median survival was 8 months in adults and 7 months in pediatric (p-value: 0.51). Raised ICP and TP53 mutation were prognostic factors in pediatric population. Radiotherapy with or without chemotherapy improved survival (p-value- <0.01)., Conclusion: Thalamic DMGs have a poor prognosis which is comparable to brainstem DMGs. Radiotherapy improves survival in these patients. However, the disease remains an enigma and further work delving into its molecular characterization should be encouraged., Competing Interests: Competing interest All authors certify that they have no affiliations with or involvement in any organisation or entity with any financial or non-financial interest in the subject matter or materials discussed in this manuscript., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Surgery for thalamic glioma is a huge challenge for neurosurgeons. Surgical treatment of adult thalamic glioma is one of the difficult problems in neurosurgery at home and abroad. Up to now, there is no relevant diagnosis and standard treatment for thalamic glioma surgical treatment, also no unified surgical management strategy. To this end, the Society for Neuro- Oncology of China (SNO-China), the Chinese Anti-Cancer Association Committee of the Glioma and the Chinese Glioma Cooperative Group (CGCG) jointly organized experts and scholars in the field of glioma to write the Chinese experts consensus on surgical treatment for adult thalamus glioma. It is hoped that through the formulation of this consensus, it will provide reference for relevant medical staff in clinical diagnosis and treatment practice, in order to improve the understanding of surgical treatment of thalamic glioma, standardize the relevant diagnosis and treatment process such as surgery, and thereby help improve the clinical prognosis of patients. [ABSTRACT FROM AUTHOR]

• The incidence of DVA in thalamic glioma was 18.18%. • Some phenotypic coexpression of shared gene may modulate the development of DVA. • Markers such as IDH1 were not associated with the development of DVA. This study aimed to assess the prevalence of developmental venous anomaly (DVA) in patients with thalamic glioma. Furthermore, we explored the association between DVA and some important biomarkers, such as IDH1 mutation, and H3K27M mutation. Patients who received tumor resection in West China Hospital between August 2009 and October 2017 were enrolled. Propensity score matching was conducted based on a logistic regression model and 1:1 matching for case and control was used to generate a new cohort from patients with meningioma. Chi-square test, t -test, univariate and multivariate analyses were employed to assess the prevalence of DVA in thalamic glioma and meningioma and to identify risk factors associated with DVA. Ninety-nine patients with thalamic glioma were enrolled in the current study (male, n = 54; female, n = 45). The mean age was 42.9 ± 15.3 years old. We identified a higher prevalence of DVA in 99 patients with thalamic glioma when compared with 99 patients with meningioma (18.18% vs. 7.07%), which was slightly lower than the prevalence of DVA in glioma reported in previous studies. Furthermore, the distribution of gender, age, and tumor grade in DVA did not reach statistical significance. Chi-square test, univariate and multivariate analyses showed that IDH1 mutation, ATRX mutation, MGMT promoter methylation, p53 mutation, MMP9, EGFR, and Top II positive expression, TERT mutation, and H3K27M mutation were not associated with the development of DVA in thalamic glioma. A higher prevalence of DVA was found in thalamic glioma compared with meningioma. [ABSTRACT FROM AUTHOR]

Thalamic gliomas in children are less suitable for surgical resection because of their location. In cases of unavoidable resection, careful surgical planning in addition to histology and extent of resection affects prognosis. A cohort of 10 pediatric patients with thalamic glioma underwent surgical resection at our department. The predominant location of tumor origins in the thalamus was defined in imaging studies. Histopathology was determined (retrospectively in a subset) according to the World Health Organization classification 2016, including the newly established type of "diffuse midline glioma, H3 K27M-mutant." Three low-grade gliomas (grade I/II) and 7 high-grade gliomas (grade III/IV) were identified. The mean follow-up period was 49.8 months. All 3 low-grade gliomas did not recur (progression-free survival, 58.3 months). Six of 7 high-grade gliomas recurred, and the patients died of the primary disease (overall survival, 28.1 months). Poor outcomes, especially when located at the pulvinar region, were noticeable, with strong predictive power for poor prognosis (P = 0.0018). The presence of H3 K27M mutation and pulvinar location were closely associated (P = 0.0036). Four of 5 patients with pulvinar region tumors developed dissemination and died of the primary disease. Pulvinar location is specifically associated with a high rate of malignancy in histology, the presence of H3 K27M mutation, and dissemination at an early disease stage. This association suggests that a distinct biological profile affects prognosis depending on location within the thalamus, especially the pulvinar. We report that tumor location is highly relevant to prognosis and should be taken into consideration when planning treatment. [ABSTRACT FROM AUTHOR]

The incidence of bilateral thalamic glioma in children is not reported in the literature. The majority of cases comprise either diffuse astrocytoma, anaplastic astrocytoma, or glioblastoma. Partial surgical resection or biopsy followed by adjuvant therapy is the usual treatment for bilateral thalamic gliomas. Prognosis is dependent on tumor grade and extent of tumor spread to surrounding critical structures. We present a rare case of bilateral thalamic pilocytic astrocytoma. Endoscopic biopsy, septostomy, and placement of a ventriculoperitoneal shunt was done followed by radiotherapy. The 36-month follow-up demonstrated radiological control of the tumor. [ABSTRACT FROM AUTHOR]

The indications of surgery for thalamic high-grade gliomas are not well established. The present study investigated the outcome of 21 patients treated by surgery and reports the high incidence of distant recurrences including disseminations after successful removal. Twenty-one patients with thalamic high-grade gliomas not invading the pyramidal tract or midbrain underwent cytoreductive surgery at our institute from June 1997 to August 2015. Surgery was performed with the aid of a neuronavigation system, electrophysiological monitoring, and fluorescence navigation. Tumor histology included 12 cases of the World Health Organization grade III and nine cases of grade IV. Gross total resection was achieved in six cases, subtotal in 13, and partial in two. Motor weakness accompanied by sensory disturbance deteriorated immediately after surgery in 13 patients. However, five patients were determined to show deterioration at 2 months after surgery. Postoperative radiation and chemotherapy were given to every patient, and median progression-free survival of patients with grade III and IV tumors was 12.1 and 7.0 months, respectively. Median overall survival of patients with grade III and IV tumors was 25.6 and 12.6 months, respectively. High incidence of distant recurrences was found, with distant lesions at recurrence in 13 of 19 patients with recurrence, suggesting the life-restricting factor in these patients. Thalamic high-grade glioma without invasion into the pyramidal tract and brainstem can be considered as a candidate for surgical resection. Distant lesion limits the survival of patients after successful resection. [ABSTRACT FROM AUTHOR]

Background. Thalamic low-grade glioma (LGG) poses a special therapeutic challenge, as complete resection is often not possible. To determine the survival outcomes of mono- and bithalamic LGG, we analyzed a large cohort of pediatric patients. Methods. From 1996 until 2012, 2618 patients were registered in the HIT-LGG 1996 and the SIOP-LGG 2004 studies. A total of 102 of these 2618 patients (3.9%) were diagnosed with a thalamic LGG with a median age at diagnosis of 8.0 years (range, 0.4-17.5 years); 87 patients (85%) had monothalamic and 15 patients (15%) had bithalamic LGG. Results. Ninety patients received at least one surgical procedure. Thirty-one patients received radiotherapy and 24 patients received chemotherapy as a first-line, nonsurgical treatment indicated by radiological tumor progression or severe/progressive clinical symptoms. Patients with monothalamic tumors showed a 10-year overall survival (OS) rate of 91%, whereas patients with bithalamic tumors only reached 65% (P = .001). Bithalamic tumors more frequently showed diffuse histology than monothalamic tumors. Patients with diffuse astrocytoma had a lower 10-year OS (68%) than those with pilocytic astrocytoma (93%). The 10-year progression-free survival rate after the start of first nonsurgical treatment was 53% in the radiotherapy group and 34% in the chemotherapy group. Conclusions. Thalamic glioma was manageable using a strategy that included surgery, observation, chemotherapy, and/or radiotherapy. Radiotherapy could be successfully deferred or obviated in a number of patients. Survival was high in among patients with monothalamic tumors. The worse prognosis associated with bithalamic tumors correlates with the higher rate of diffuse histology in this subgroup, precluding total or near-total resection. [ABSTRACT FROM AUTHOR]

The 2016 World Health Organization Classification of Tumours of the Central Nervous System was revised to include a new diagnostic entity, diffuse midline glioma, H3 K27M–mutant (DMG-K27M), a highly aggressive tumor with a mean survival time of 1 year after diagnosis. DMG-K27M is classified as a World Health Organization grade IV tumor regardless of histopathologic features, and there is currently no effective treatment for it despite ongoing research. We present a case of a 39-year-old man with a slow-growing thalamic glioma with histone H3 lysine 27-to-methionine mutation. This patient received surgical intervention 3 years after the initial discovery of the tumor. Because the patient did not receive any preoperative treatment for DMG-K27M, this case reflects 1 possible natural course of progression for this type of malignancy. There are currently no effective therapeutic options for treatment of DMG-K27M. The slow tumor growth and prolonged survival time (≥ 3 years) in the absence of intervention in this case serve as a reminder that much is still not known about histone H3 lysine 27-to-methionine mutation and how it impacts the pathophysiology, diagnosis, treatment, and prognosis of the disease. Careful evaluation is warranted to determine if early intervention is the best approach when treating DMG-K27M. [ABSTRACT FROM AUTHOR]

Bilateral thalamic glioma is a rare type of primary thalamic tumor. It presents clinically with personality changes and dementia rather than mass effect or focal neurological deficit. Imaging findings are somewhat characteristic with the diffuse homogenous enlargement of bilateral thalami with altered attenuation or signal intensity on computerized tomography and magnetic resonance imaging, respectively. This tumor is refractory to radiotherapy and chemotherapy and survival beyond 2 years after diagnosis is rare. This report emphasizes the need of neuroimaging in a patient with dementia to identify this rare devastating tumor early.

We report a case of 48-year old woman who presented with dementia, progressive mental decline, personality change, paresis of the right lower extremity, and gait ataxia. Magnetic resonance imaging (MRI) T1-weighted image revealed bilateral thalamic swelling with homogenous low signal intensity and mild contrast enhancement with gadolinium. The T2- weighted image showed high intensity lesions in the bilateral thalamus, septum pellucidum and fornix. A CT-guided stereotactic biopsy of the lesion revealed fibrillary astrocytoma grade III as per WHO classification. Bilateral thalamic gliomas are very rare tumours and when present may resemble other benign diseases having similar clinical presentations DOI: http://dx.doi.org/10.3126/jonmc.v3i1.10059 Journal of Nobel Medical College Vol.3(1) 2014; 71-73

Background The thalamus is a deep-seated and crucial structure for the sensorimotor system. It has been long considered a surgically inaccessible area because of the morbidity associated with surgical resections. Astrocytomas of the thalamus are usually treated with bioptic procedures followed by adjuvant treatments. Intraoperative neurophysiologic monitoring (IONM) allows safe and satisfactory resections of lobar gliomas, but few data are available for thalamic lesions. The aim of this study was to review the outcome of a small series of patients with thalamic astrocytomas that were treated with surgical resection with the aid of IONM. Methods Surgical resection with IONM was performed in 5 patients with thalamic astrocytomas (1 grade I, 1 grade II, 2 grade III, 1 grade IV). Two astrocytomas were in the dominant hemisphere. Preoperative and postoperative neuropsychological assessments were performed in 3 patients. IONM was tailored to the individual patient and consisted of transcranial motor evoked potential monitoring, cortical motor evoked potential monitoring, somatosensory evoked potential monitoring, direct electrical stimulation, electroencephalography, and electrocorticography. Results None of the patients experienced permanent motor deficits; 2 patients had a transient hemiparesis requiring rehabilitation; 1 patient had a transient aphasia, and 1 patient had permanent aphasia. None of the patients had intraoperative seizures, but 1 patient experienced postoperative transient status epilepticus. The extent of resection on postoperative volumetric magnetic resonance imaging was >70% in all cases. Conclusions Surgical resection of thalamic astrocytomas appeared to be effective and relatively safe when guided by IONM. Larger series of patients are required to confirm these preliminary data. [ABSTRACT FROM AUTHOR]

Paediatric brain tumours arising in the thalamus present significant diagnostic and therapeutic challenges to physicians due to their sensitive midline location. As such, genetic analysis for biomarkers to aid in the diagnosis, prognosis and treatment of these tumours is needed. Here, we identified 64 thalamic gliomas with clinical follow-up and characterized targeted genomic alterations using newly optimized droplet digital and NanoString-based assays. The median age at diagnosis was 9.25 years (range, 0.63-17.55) and median survival was 6.43 (range, 0.01-27.63) years. Our cohort contained 42 and 22 tumours reviewed as low and high grade gliomas, respectively. Five (12 %) low grade and 11 (50 %) high grade gliomas were positive for the H3F3A/HIST1H3B K27M (H3K27M) mutation. Kaplan-Meier survival analysis revealed significantly worse overall survival for patients harbouring the H3K27M mutation versus H3F3A/ HIST1H3B wild type (H3WT) samples (log-rank p < 0.0001) with a median survival of 1.02 vs. 9.12 years. Mitogen-activated protein kinase (MAPK) pathway activation via BRAF or FGFR1 hotspot mutations or fusion events were detected in 44 % of patients, and was associated with long-term survival in the absence of H3K27M (log-rank p < 0.0001). Multivariate analysis demonstrated H3K27M status and high grade histology to be the most significant independent predictors of poor overall survival with hazard ratios of 6.945 and 7.721 (p < 0.0001), respectively. In contrast, MAPK pathway activation is a predictor of favourable patient outcome, although not independent of other clinical factors. Importantly, we show that low grade malignancies may harbour H3K27M mutations and that these tumours show a dismal survival compared to low grade H3WT cases. Our data strongly supports the inclusion of targeted genetic testing in childhood thalamic tumours to most accurately stratify patients into appropriate risk groups. [ABSTRACT FROM AUTHOR]

Background Thalamic gliomas are rare tumors that constitute 1%–5% of all central nervous system tumors. Despite advanced techniques and equipment, surgical resection remains challenging because of the vital structures adjacent to the tumor. Intraoperative magnetic resonance imaging (MRI) might play an active role during brain tumor surgery because it compensates for brain shift or operation-induced hemorrhage, which are challenging issues for neurosurgeons. Methods We reviewed 38 patients treated surgically under intraoperative MRI guidance between January 2008 and July 2015 at our center. Preoperative, intraoperative, and postoperative MRI scans were reviewed. Preoperative and postoperative motor power, morbidity and mortality, resection rate, surgical approach, pathologic results, and patient demographics were also reviewed. Results Mean patient age was 37 years ± 18; 12 patients were included in the low-grade group, and 26 patients were included in the high-grade group. Under intraoperative MRI guidance, the gross total resection rate was increased from 16 (42.1%) to 26 (68.4%), and the near-total or subtotal resection rate was increased from 5 (13.2%) to 9 (23.7%). Hematoma formation was discovered in 3 patients on intraoperative MRI scan; each patient underwent a hemostatic operation immediately. Conclusions With improvements in neurosurgical techniques and equipment, surgical resection is considered feasible in patients with thalamic gliomas. Intraoperative MRI may be helpful in achieving the maximal resection rate with minimal surgical-related morbidity. However, because of severe disease progression, the overall prognosis is unfavorable. [ABSTRACT FROM AUTHOR]

This study aimed to identify (1) the thalamic gliomas suitable for surgical resection and (2) the appropriate surgical approach based on their location and the displacement of the posterior limb of the internal capsule (PLIC). A retrospective study over a 5-year period (from 2006 to 2010) was performed in 41 patients with thalamic gliomas. The mean age of these patients was 20.4 years (range, 2-65 years). Twenty (49 %) tumors were thalamic, 19 (46 %) were thalamopeduncular, and 2 (5 %) were bilateral. The PLIC, based on T2-weighted magnetic resonance axial sections, was displaced anterolaterally in 23 (56 %) cases and laterally in 6 (14 %) cases. It was involved by lesion in eight (20 %) cases and could not be identified in four (10 %) cases. Resection, favored in patients with well-defined, contrast-enhancing lesions, was performed in 34 (83 %) cases, while a biopsy was resorted to in 7 (17 %) cases. A gross total resection or near total resection (>90 %) could be achieved in 26 (63 %) cases. The middle temporal gyrus approach, used when the PLIC was displaced anterolaterally, was the commonly used approach (63.5 %). Common pathologies were pilocytic astrocytoma (58 %) in children and grade III/IV astrocytomas (86 %) in adults. Preoperative motor deficits improved in 64 % of the patients with pilocytic lesions as compared to 0 % in patients with grade III/IV lesions ( P value, 0.001). Postoperatively, two patients (5 %) had marginal worsening of motor power, two patients developed visual field defects, and one patient developed a third nerve paresis. Radical resection of thalamic gliomas is a useful treatment modality in a select subset of patients and is the treatment of choice for pilocytic astrocytomas. Tailoring the surgical approach, depending on the relative position of the PLIC, has an important bearing on outcome. [ABSTRACT FROM AUTHOR]

Deep-seated gliomas, including thalamic gliomas, have a poor prognosis because of difficulty of accessibility for surgery. In addition, an infiltrative pattern of the tumor is related to a poor prognosis. In this study, the infiltrative/invasive profile of the proliferating tumor cells of a right thalamic glioma was evaluated in an autopsied brain. A 71-year-old man died from extensive infiltration of a right thalamic glioma. The distribution of the proliferating tumor cells at the right thalamic tumor level was represented by the topographic map of MIB-1 labeling indices (LI) on the whole-brain coronal slice, and this map was analyzed with pathological findings and postmortem T2-weighted magnetic resonance imaging (MRI). The highest MIB-1 LI was 24% for the whole autopsy brain at the thalamic tumor level, whereas the MIB-1 LI was 21% for the biopsy sample of the right thalamic glioma. Because this patient survived only 9 months after diagnosis of the tumor as anaplastic astrocytoma, it was confirmed that 21% MIB-1 LI of the biopsy sample was relevant to his prognosis. The topographic map of MIB-1 LI showed that the proliferating tumor cells of the right thalamic glioma invaded the ventricular walls and the contralateral thalamus by the periventricular route, but there was no exophytic extension to the cortex. In conclusion, topographic analysis of the proliferative potential detected by MIB-1 immunostaining provides information on the growth pattern of human glioma. [ABSTRACT FROM AUTHOR]

Objective: The object of this study was to present the surgical results of a large, single-surgeon consecutive series of patients who had undergone transcisternal (TCi) or transcallosal-transventricular (TCTV) endoscope-assisted microsurgery for thalamic lesions., Methods: This is a retrospective study of a consecutive series of patients harboring thalamic lesions and undergoing surgery at one institution between February 2007 and August 2019. All surgical and patient-related data were prospectively collected. Depending on the relationship between the lesion and the surgically accessible thalamic surfaces (lateral ventricle, velar, cisternal, and third ventricle), one of the following surgical TCi or TCTV approaches was chosen: anterior interhemispheric transcallosal (AIT), posterior interhemispheric transtentorial subsplenial (PITS), perimedian supracerebellar transtentorial (PeST), or perimedian contralateral supracerebellar suprapineal (PeCSS). Since January 2018, intraoperative MRI has also been part of the protocol. The main study outcome was extent of resection. Complete neurological examination took place preoperatively, at discharge, and 3 months postoperatively. Descriptive statistics were calculated for the whole cohort., Results: In the study period, 92 patients underwent surgery for a thalamic lesion: 81 gliomas, 6 cavernous malformations, 2 germinomas, 1 metastasis, 1 arteriovenous malformation, and 1 ependymal cyst. In none of the cases was a transcortical approach adopted. Thirty-five patients underwent an AIT approach, 35 a PITS, 19 a PeST, and 3 a PeCSS. The mean follow-up was 38 months (median 20 months, range 1-137 months). No patient was lost to follow-up. The mean extent of resection was 95% (median 100%, range 21%-100%), and there was no surgical mortality. Most patients (59.8%) experienced improvement in their Karnofsky Performance Status. New permanent neurological deficits occurred in 8 patients (8.7%). Early postoperative (< 3 months after surgery) problems in CSF circulation requiring diversion occurred in 7 patients (7.6%; 6/7 cases in patients with high-grade glioma)., Conclusions: Endoscope-assisted microsurgery allows for the removal of thalamic lesions with acceptable morbidity. Surgeons must strive to access any given thalamic lesion through one of the four accessible thalamic surfaces, as they can be reached through either a TCTV or TCi approach with no or minimal damage to normal brain parenchyma. Patients harboring a high-grade glioma are likely to develop a postoperative disturbance of CSF circulation. For this reason, the AIT approach should be favored, as it facilitates a microsurgical third ventriculocisternostomy and allows intraoperative MRI to be done.