AB004. Transsylvian approach for radical resection of insular gliomas: emphasizing the importance of the transsylvian approach for elderly patients with Zone II and III insular gliomas.

BACKGROUND: Insular gliomas present significant challenges due to their deep-seated location and proximity to critical structures, including sylvian veins, middle cerebral arteries (MCAs), lenticulostriate arteries, long insular arteries, and functional cortices and white matter tracts. The Berger-Sanai classification categorizes them into four zones (I-IV), providing a framework for understanding insular gliomas. The key factors for successful insular glioma removal are achieving the greatest insular exposure and surgical freedom. There are two main types of approach methods, such as transsylvian approach with meticulous wider dissection of the sylvian fissure and transcorticosubcortical approach with intraoperative functional brain mapping under awake surgery to remove the functionally silent cortices and white matter tracts. Because splitting the distal sylvian fissure is more challenging, a transcortical approach through the parietorolandic operculum in awake patients has been reported to be more effective access to the posterior insular gliomas (Zone II and III) in the dominant hemisphere. The object of this study emphasize the importance of the transsylvian approach for radical resection of insular gliomas. METHODS: We retrospectively analyzed our experiences with radically resected insulo-opercular gliomas. Basically, we pursue the transsylvian approach for resecting insular gliomas without removal of any normal brain. RESULTS: Motor pathways running beneath the parietorolandic operculum can be damaged by ischemia caused by sacrificing the medullary arteries (MAs) arising from the pial arteries of the M3 and M4 portions of the MCA. Motor deficit after resection of this area was significantly found in the elderly patients. This phenomenon might be described by the age-associated decreasing the vascular reserve capacity. Autopsy brains showed that the sclerotic rate of the MAs increased with age and hypertension. Even with the intraoperative functional brain mapping, we cannot avoid the ischemic complication caused by sacrificing the MAs during stepwise removal of the functionally silent cortices and white matter tracts. CONCLUSIONS: We make a suggestion not to remove the parietorolandic operculum in elderly patients with insular gliomas located at Zone II and III. Distal transsylvian approach should be applied.

Transsylvian Insular Glioma Surgery.

Currently, there is a unanimous opinion that the first line of the treatment of insular gliomas is microsurgical removal.1-3 At the same time, surgery of insular glial tumors remains a challenge because of the complex anatomy of the insular region. Among the most crucial anatomical structures are branches of the middle cerebral artery (MCA), lenticulostriate arteries (LSAs), and corticospinal tract.4 Surgery of the insular glioma becomes much more complicated in cases when the tumor extends to the anterior perforated substance, which, according to our data, occurs in 29,1% of cases.5 We present a 33-year-old woman with a history of generalized seizures (Video1). Magnetic resonance imaging scan revealed a left insular lobe tumor with tumor expansion to the anterior perforated substance and mesial temporal lobe. Given the large size of the tumor and the patient's symptoms, the decision was made in favor of surgery. The video demonstrates the technique of a Sylvian fissure dissection, manipulations with MCA branches and LSA, removal of the tumor from the region of the anterior perforated substance, and a discussion of surgical nuances and safety aspects. The most challenging part of the operation was to identify and protect the LSAs.6 Advanced microsurgical techniques, and the correct patient selection for surgical treatment, are cornerstones for a successful outcome and provide an acceptable frequency of postoperative neurologic deficits in patients who undergo surgery of insular gliomas through the transsylvian approach.

Factors affecting the extent of resection and neurological outcomes following transopercular resection of insular gliomas.

BACKGROUND: Surgical resection of insular gliomas is a challenge. TO resection is considered more versatile and has lower risk of vascular damage. In this study, we aimed to understand the factors that affect resection rates, ischemic changes and neurological outcomes and studied the utility of IONM in patients who underwent TO resection for IGs. METHODS: Retrospective analysis of 66 patients with IG who underwent TO resection was performed. RESULTS: Radical resection was possible in 39% patients. Involvement of zone II and the absence of contrast enhancement predicted lower resection rate. Persistent deficit rate was 10.9%. Although dominant lobe tumors increased immediate deficit and fronto-orbital operculum involvement reduced prolonged deficit rate, no tumor related factor showed significant association with persistent deficits. 45% of patients developed a postoperative infarct, 53% of whom developed deficits. Most affected vascular territory was lenticulostriate (39%). MEP changes were observed in 9/57 patients. 67% of stable TcMEPs and 74.5% of stable strip MEPs did not develop any postoperative motor deficits. Long-term deficits were seen in 3 and 6% patients with stable TcMEP and strip MEPs respectively. In contrast, 25% and 50% of patients with reversible strip MEP and Tc MEP changes respectively had persistent motor deficits. DWI changes were clinically more relevant when accompanied by MEP changes intraoperatively, with persistent deficit rates three times greater when MEP changes occurred than when MEPs were stable. CONCLUSION: Radical resection can be achieved in large, multizone IGs, with reasonable outcomes using TO approach and multimodal intraoperative strategy with IONM.

Survival outcome and predictors of WHO grade 2 and 3 insular gliomas: A classification based on the tumor spread.

OBJECTIVE: The study aimed to identify if clinical features and survival outcomes of insular glioma patients are associated with our classification based on the tumor spread. METHODS: Our study included 283 consecutive patients diagnosed with histological grade 2 and 3 insular gliomas. A new classification was proposed, and tumors restricted to the paralimbic system were defined as type 1. When tumors invaded the limbic system (referred to as the hippocampus and its surrounding structures in this study) simultaneously, they were defined as type 2. Tumors with additional internal capsule involvement were defined as type 3. RESULTS: Tumors defined as type 3 had a higher age at diagnosis (p = 0.002) and a higher preoperative volume (p < 0.001). Furthermore, type 3 was more likely to be diagnosed as IDH wild type (p < 0.001), with a higher rate of Ki-67 index (p = 0.015) and a lower rate of gross total resection (p < 0.001). Type 1 had a slower tumor growth rate than type 2 (mean 3.3%/month vs. 19.8%/month; p < 0.001). Multivariate Cox regression analysis revealed the extent of resection (HR 0.259, p = 0.004), IDH status (HR 3.694, p = 0.012), and tumor spread type (HR = 1.874, p = 0.012) as independent predictors of overall survival (OS). Tumor grade (HR 2.609, p = 0.008), the extent of resection (HR 0.488, p = 0.038), IDH status (HR 2.225, p = 0.025), and tumor spread type (HR 1.531, p = 0.038) were significant in predicting progression-free survival (PFS). CONCLUSION: The current study proposes a classification of the insular glioma according to the tumor spread. It indicates that the tumors defined as type 1 have a relatively better nature and biological characteristics, and those defined as type 3 can be more aggressive and refractory. Besides its predictive value for prognosis, the classification has potential value in formulating surgical strategies for patients with insular gliomas.

Surgical treatment for insular gliomas. A systematic review and meta-analysis on behalf of the EANS neuro-oncology section.

Introduction: The appropriate surgical management of insular gliomas is controversial. Management strategies vary considerably between centers. Research question: To provide robust resection, functional and epilepsy outcome figures, study growth patterns and tumor classification paradigms, analyze surgical approaches, mapping/monitoring strategies, surgery for insular glioblastoma, as well as molecular findings, and to identify open questions for future research. Material and methods: On behalf of the EANS Neuro-oncology Section we performed a systematic review and meta-analysis (using a random-effects model) of the more current (2000-2023) literature in accordance with the PRISMA guidelines. Results: The pooled postoperative motor and speech deficit rates were 6.8% and 3.6%. There was a 79.6% chance for postoperative epilepsy control. The postoperative KPI was 80-100 in 83.5% of cases. Functional monitoring/mapping paradigms (which may include awake craniotomies) seem mandatory. (Additional) awake surgery may result in slightly better functional but also worse resection outcomes. Transcortical approaches may carry a lesser rate of (motor) deficits than transsylvian surgeries. Discussion and conclusions: This paper provides an inclusive overview and analysis of current surgical management of insular gliomas. Risks and complication rates in experienced centers do not necessarily compare unfavorably with the results of routine neuro-oncological procedures. Limitations of the current literature prominently include a lack of standardized outcome reporting. Questions and issues that warrant more attention include surgery for insular glioblastomas and how to classify the various growth patterns of insular gliomas.

What is the cognitive footprint of insular glioma?

Cognitive impairment has a profound deleterious impact on long-term outcomes of glioma surgery. The human insula, a deep cortical structure covered by the operculum, plays a role in a wide range of cognitive functions including interceptive thoughts and salience processing. Both low-grade (LGG) and high-grade gliomas (HGG) involve the insula, representing up to 25% of LGG and 10% of HGG. Surgical series from the past 30 years support the role of primary cytoreductive surgery for insular glioma patients; however, reported cognitive outcomes are often limited to speech and language function. The breath of recent neuroscience literature demonstrates that the insula plays a broader role in cognition including interoceptive thoughts and salience processing. This article summarizes the vast functional role of the healthy human insula highlighting how this knowledge can be leveraged to improve the care of patients with insular gliomas.

Radiomic profiling for insular diffuse glioma stratification with distinct biologic pathway activities.

Current literature emphasizes surgical complexities and customized resection for managing insular gliomas; however, radiogenomic investigations into prognostic radiomic traits remain limited. We aimed to develop and validate a radiomic model using multiparametric magnetic resonance imaging (MRI) for prognostic prediction and to reveal the underlying biological mechanisms. Radiomic features from preoperative MRI were utilized to develop and validate a radiomic risk signature (RRS) for insular gliomas, validated through paired MRI and RNA-seq data (N = 39), to identify core pathways underlying the RRS and individual prognostic radiomic features. An 18-feature-based RRS was established for overall survival (OS) prediction. Gene set enrichment analysis (GSEA) and weighted gene coexpression network analysis (WGCNA) were used to identify intersectional pathways. In total, 364 patients with insular gliomas (training set, N = 295; validation set, N = 69) were enrolled. RRS was significantly associated with insular glioma OS (log-rank p = 0.00058; HR = 3.595, 95% CI:1.636-7.898) in the validation set. The radiomic-pathological-clinical model (R-P-CM) displayed enhanced reliability and accuracy in prognostic prediction. The radiogenomic analysis revealed 322 intersectional pathways through GSEA and WGCNA fusion; 13 prognostic radiomic features were significantly correlated with these intersectional pathways. The RRS demonstrated independent predictive value for insular glioma prognosis compared with established clinical and pathological profiles. The biological basis for prognostic radiomic indicators includes immune, proliferative, migratory, metabolic, and cellular biological function-related pathways.

Preoperative plasticity in the functional naming network of patients with left insular gliomas.

Plasticity could take place as a compensatory process following brain glioma growth. Only a few studies specifically explored plasticity in patients affected by a glioma invading the left insula; even more, plasticity of the insular cortex in task-based functional language network is almost unexplored. In the current study, we explored potential plasticity in a consecutive series of 22 patients affected by a glioma centered to the left insula, by comparing their preoperative object-naming functional network with that of a group of healthy controls. After having controlled for demographic variables, fMRI results showed that patients vs. controls activated a cluster in the right, contralesional pars triangularis including the Broca's area. On the other hand, controls did not significantly activate any brain region more than patients. At behavioral level, patients retained a generally preserved naming performance as well as a proficient language processing profile. These findings suggest that involvement of language-specific areas in the healthy hemisphere could help compensate for the left, affected insula, thus allowing preservation of the naming functions. Results are commented in relation to lesion site, naming performance, and potential relevance for neurosurgery.

A preliminary study on corticospinal tract morphology in incidental and symptomatic insular low-grade glioma: implications for post-surgical motor outcomes.

OBJECTIVE: Our study aimed to investigate the shape and diffusion properties of the corticospinal tract (CST) in patients with insular incidental and symptomatic low-grade gliomas (LGGs), especially those in the incidental group, and evaluate their association with post-surgical motor function. METHODS: We performed automatic fiber tracking on 41 LGG patients, comparing macroscopic shape and microscopic diffusion properties of CST between ipsilateral and contralateral tracts in both incidental and symptomatic groups. A correlation analysis was conducted between properties of CST and post-operative motor strength grades. RESULTS: In the incidental group, no significant differences in mean diffusion properties were found between bilateral CST. While decreased anisotropy of the CST around the superior limiting sulcus and increased axial diffusivity of the CST near the midbrain level were noted, there was no significant correlation between pre-operative diffusion metrics and post-operative motor strength. In comparison, we found significant correlations between the elongation of the affected CST in the preoperative scans and post-operative motor strength in short-term and long-term follow ups (p = 1.810 × 10-4 and p = 9.560 × 10-4, respectively). CONCLUSIONS: We found a significant correlation between CST shape measures and post-operative motor function outcomes in patients with incidental insular LGGs. CST morphology shows promise as a potential prognostic factor for identifying functional deficits in this patient population.

The transfrontal isthmus approach for insular glioma surgery.

OBJECTIVE: The classic transopercular or transsylvian approach to insular gliomas removes the tumor laterally through the insular cortex. This study describes a new anteroposterior approach through the frontal isthmus for insular glioma surgery. METHODS: The authors detailed the surgical techniques for resection of insular gliomas through the transfrontal isthmus approach. Fifty-nine insular gliomas with at least Berger-Sanai zone I involvement were removed with the new approach, and extent of resection and postoperative neurological outcomes were assessed. RESULTS: Fifty-nine patients were enrolled in the study, including 35 men and 24 women, with a mean (range) age 44.3 (19-75) years. According to the Berger-Sanai classification system, the most common tumor was a giant glioma (67.8%), followed by involvement of zones I and IV (18.6%). Twenty-two cases were Yasargil type 3A/B, and 37 cases were Yasargil type 5A/B. The average angle between the lateral plane of the putamen and sagittal line was 33.53°, and the average width of the isthmus near the anterior insular point was 33.33 mm. The average angle between the lateral plane of the putamen and the sagittal line was positively correlated with the width of the isthmus near the anterior insular point (r = 0.935, p < 0.0001). The median (interquartile range [IQR]) preoperative tumor volume was 67.82 (57.64-92.19) cm3. Of 39 low-grade gliomas, 26 (66.67%) were totally resected; of 20 high-grade gliomas, 19 (95%) were totally resected. The median (IQR) extent of resection of the whole group was 100% (73.7%-100%). Intraoperative diffusion-weighted imaging showed no cases of middle cerebral artery- or lenticulostriate artery-related stroke. Extent of insular tumor resection was positively correlated with the angle of the lateral plane of the putamen and sagittal line (r = -0.329, p = 0.011) and the width of the isthmus near the anterior insular point (r = -0.267, p = 0.041). At 3 months postoperatively, muscle strength grade exceeded 4 in all cases, and all patients exhibited essentially normal speech. The median (IQR) Karnofsky performance score at 3 months after surgery was 90 (80-90). CONCLUSIONS: The transfrontal isthmus approach changes the working angle from lateral-medial to anterior-posterior, allowing for maximal safe removal of insular gliomas.

Microscope-based augmented reality with diffusion tensor imaging and fluorescein in insular glioma resection.

Maximal safe resection is the goal of insular glioma surgery. The combination of intraoperative augmented reality (AR) diffusion tensor imaging (DTI) fiber tracking with fluorescein dye (F) helps achieve this goal throughout a microscope-based visualization of the tumor and white matter fiber tracts. The aim of the present video article was to show the technical key aspects of DTI-F microscope-based AR-assisted surgery during the gross-total resection of an insular Berger-Sanai type I+IV high-grade glioma in a 63-year-old patient, performed through a pterional transsylvian approach. The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID2157.

Sensitivity of three-dimensional time-of-flight 3.0 ​T magnetic resonance angiography in visualizing the number and course of lenticulostriate arteries in patients with insular gliomas.

Background: Neurosurgical resection of insular gliomas is complicated by the possibility of iatrogenic injury to the lenticulostriate arteries (LSAs) and is associated with devastating neurological complications, hence the need to accurately assess the number of LSAs and their relationship to the tumor preoperatively. Methods: The study included 24 patients with insular gliomas who underwent preoperative 3D-TOF MRA to visualize LSAs. The agreement of preoperative magnetic resonance imaging with intraoperative data in terms of the number of LSAs and their invasion by the tumor was assessed using the Kendall rank correlation coefficient and Cohen's Kappa with linear weighting. Agreement between experts performing image analysis was estimated using Cohen's Kappa with linear weighting. Results: The number of LSAs arising from the M1 segment varied from 0 to 9 (mean 4.3 â€‹± â€‹0.37) as determined by 3D-TOF MRA and 2-6 (mean 4.25 â€‹± â€‹0.25) as determined intraoperatively, κ â€‹= â€‹0.51 (95% CI: 0.25-0.76) and τ â€‹= â€‹0.64 (p â€‹< â€‹0.001). LSAs were encased by the tumor in 11 patients (confirmed intraoperatively in 9 patients). LSAs were displaced medially in 8 patients (confirmed intraoperatively in 8 patients). The tumor partially involved the LSAs and displaced them in 5 patients (confirmed intraoperatively in 7 patients), κ â€‹= â€‹0.87 (95% CI: 0.70-1), τ â€‹= â€‹0.93 (p â€‹< â€‹0.001). 3D-TOF MRA demonstrated high sensitivity (100%, 95% CI: 0.63-1) and high specificity (86.67%, 95% CI: 0.58-0.98) in determining the LSA-tumor interface. Conclusions: 3D-TOF MRA at 3T demonstrated sensitivity in determining the LSA-tumor interface and the number of LSAs in patients with insular gliomas.

Balancing the Extent of Resection and Ischemic Complications in Insular Glioma Surgery: Technical Nuances and Proposal of a Novel Composite Postoperative Outcome Index.

Background: Maximal safe resection remains the most desired goal of insular glioma surgery. Intraoperative surgical adjuncts provide better tumor visualization and real-time "safety" data but remain limited due to a high cost and limited availability. Objective: To highlight the importance of anatomical landmarks in insular glioma resection and avoidance of vascular complications. We also propose to objectify the onco-functional balance in insular glioma surgery. Methods: Forty-six insular gliomas operated upon by a single surgeon between January 2015 and February 2020 were reviewed, focusing on the operative technique and clinical outcomes. A novel composite postoperative outcome index (CPOI) was designed, comprising the extent of resection and permanent postoperative deficits, and utilized to assess the surgical outcomes. Results: Gross-total, near-total, and subtotal resections were achieved in 10.9%, 52.1% (n = 24), and 36.9% (n = 17) patients, respectively. The median overall survival (OS) was 20 months (95% CI = 9.56-30.43). CPOI was optimal in 38 patients (82.6%). A well-defined tumor margin (P = 0.01) and surgeon's experience (P = 0.04) were significantly associated with an optimal CPOI. Out of seven (15.2%) patients who developed permanent neurological deficits, three (6.5%) patients had severe disability. Favorable prognostic factors of survival included younger age (<40 years) (P = 0.002), tumors with only frontal lobe extension (P = 0.011), tumors with caudate head involvement (P = 0.04), and non-glioblastoma histology (P = 0.006). Conclusion: Tumor margin and increasing surgeon experience are critical to an optimal postoperative outcome. Respecting the basi-sulcal plane is key to lenticulostriate artery preservation. Caudate head involvement is a new favorable prognostic factor in insular gliomas.

Transopercular Approach to Resection of Dominant Hemisphere Diffuse Insular Glioma Using Multimodal Intraoperative Strategy with Awake Mapping.

Background: Deep location as well as relation to major vascular structures and eloquent brain areas make insular glioma resection challenging. Transsylvian and transopercular approaches have been described for resection of these tumors. Objective: We illustrate the anatomical relations of a dominant hemisphere insular glioma and present the video demonstrating the step-wise resection of the same via frontal transopercular approach. Surgical Procedure: A 27-year-old lady with dominant hemisphere insular glioma underwent awake surgery through a transopercular approach with cortical and subcortical mapping using direct electrical stimulation for resection of the same. Result: Gross total resection of left insular glioma was achieved without any fresh postoperative deficits. Conclusion: Awake transopercular approach with intraoperative motor, language, and neuropsychological monitoring helps achieve maximum safe resection of insular glioma in the dominant cerebral hemisphere.

Optimized Tractography Mapping and Quantitative Evaluation of Pyramidal Tracts for Surgical Resection of Insular Gliomas: a Correlative Study with Diffusion Tensor Imaging-Derived Metrics and Patient Motor Strength.

We investigate the correlation between diffusion tensor imaging (DTI)-derived metric statistics and motor strength grade of insular glioma patients after optimizing the pyramidal tract (PT) delineation. Motor strength grades of 45 insular glioma patients were assessed. All the patients underwent structural and diffusion MRI examination before and after surgery. We co-registered pre- and post-op datasets, and a two-tensor unscented Kalman filter (UKF) algorithm was employed to delineate bilateral PTs after DWI pre-processing. The tractography results were voxelized, and their labelmaps were cropped according to the location of frontal and insular parts of the lesion. Both the whole and cropped labelmaps were used as regions of interest to analyze fractional anisotropy (FA) and Trace statistics; hence, their ratios were calculated (lesional side tract/contralateral normal tract). The combination of DWI pre-processing and two-tensor UKF algorithm successfully delineated bilateral PTs of all the patients. It effectively accomplished both full fiber delineation within the edema and an extensive lateral fanning that had a favorable correspondence to the bilateral motor cortices. Before surgery, correlations were found between patients' motor strength grades and ratios of PT volume and FA standard deviation (SD). Nearly 3 months after surgery, correlations were found between motor strength grades and the ratios of metric statistics as follows: whole PT volume, whole mean FA, and FA SD. We substantiated the correlation between DTI-derived metric statistics and motor strength grades of insular glioma patients. Moreover, we posed a workflow for comprehensive pre- and post-op DTI quantitative research of glioma patients.

Reduced sensitivity to delayed time and delayed reward of the post-operative insular glioma patients in delay discounting.

Previous studies have shown that the insula is closely related to addiction, and the structure's role in delay discounting can be measured by a specific task, but the specific role of the insula has been less studied. In this study, we first conducted a lesion study in which we recruited healthy controls (n = 30) and patients with unilateral insula injury (n = 16) to complete a behavioral delay discounting task. Then we conducted a functional magnetic resonance imaging (fMRI) study, and a separate group healthy volunteers (n = 51) completed a delay discounting task during the fMRI scan. The lesion study showed a significant difference between the two groups in the delay discounting task, which revealed that insula injury was associated with impaired decision making. The fMRI study revealed choice-sensitive insula activation that was modulated by delayed time and delayed reward, indicating an important role of the insula in delay discounting. Overall, our results provide evidence for a role of the insular lobe in delay discounting and suggests that this structure may be considered an important factor in the future treatment and diagnosis of addiction disorders.

Correlation of anatomical involvement patterns of insular gliomas with subnetworks of the limbic system.

OBJECTIVE: Gliomas frequently involve the insula both primarily and secondarily by invasion. Despite the high connectivity of the human insula, gliomas do not spread randomly to or from the insula but follow stereotypical anatomical involvement patterns. In the majority of cases, these patterns correspond to the intrinsic connectivity of the limbic system, except for tumors with aggressive biology. On the basis of these observations, the authors hypothesized that these different involvement patterns may be correlated with distinct outcomes and analyzed these correlations in an institutional cohort. METHODS: Fifty-nine patients who had undergone surgery for insular diffuse gliomas and had complete demographic, pre- and postoperative imaging, pathology, molecular genetics, and clinical follow-up data were included in the analysis (median age 37 years, range 21-71 years, M/F ratio 1.68). Patients with gliomatosis and those with only minor involvement of the insula were excluded. The presence of T2-hyperintense tumor infiltration was evaluated in 12 anatomical structures. Hierarchical biclustering was used to identify co-involved structures, and the findings were correlated with established functional anatomy knowledge. Overall survival was evaluated using Kaplan-Meier and Cox proportional hazards regression analysis (17 parameters). RESULTS: The tumors involved the anterior insula (98.3%), posterior insula (67.8%), temporal operculum (47.5%), amygdala (42.4%), frontal operculum (40.7%), temporal pole (39%), parolfactory area (35.6%), hypothalamus (23.7%), hippocampus (16.9%), thalamus (6.8%), striatum (5.1%), and cingulate gyrus (3.4%). A mean 4.2 ± 2.6 structures were involved. On the basis of hierarchical biclustering, 7 involvement patterns were identified and correlated with cortical functional anatomy (pure insular [11.9%], olfactocentric [15.3%], olfactoopercular [33.9%], operculoinsular [15.3%], striatoinsular [3.4%], translimbic [11.9%], and multifocal [8.5%] patterns). Cox regression identified hippocampal involvement (p = 0.006) and postoperative tumor volume (p = 0.027) as significant negative independent prognosticators of overall survival and extent of resection (p = 0.015) as a significant positive independent prognosticator. CONCLUSIONS: The study findings indicate that insular gliomas primarily involve the olfactocentric limbic girdle and that involvement in the hippocampocentric limbic girdle is associated with a worse prognosis.

Seizure control after surgical resection of insular glioma.

Insular gliomas most commonly present with drug-resistant seizures, irrespective of the tumour grade. Even though surgery is the mainstay of treatment, complex anatomical location and close proximity to eloquent cortex makes surgical resection difficult. Herein the authors have reviewed the literature with regards to seizure control after surgical management of these tumours. The review does not address quality of life, or survival benefits of surgery. In summary, excision of these gliomas significantly improves seizure control, and extent of resection along-with trans-cortical approach are important predictors of seizure outcome.

Seizure Outcome After Surgery for Insular High-Grade Glioma.

BACKGROUND: The insular cortex is an eloquent island of mesocortex surrounded by vital structures making this region relatively challenging to neurosurgeons. Historically, lesions in this region were considered too high risk to approach given the strong chance of poor surgical outcome. Advances in recent decades have meant that surgeons can more safely access this eloquent region. Seizure outcome after excision of insular low-grade gliomas is well reported, but little is known about seizure outcomes after excision of insular high-grade gliomas. METHODS: A retrospective analysis was performed of all patients presenting with new-onset seizures during 2015-2019 who underwent excision of an insular high-grade glioma at 3 regional neurosurgical centers in the United Kingdom. RESULTS: We identified 38 patients with a mean (SD) age of 45.7 (15.3) years with median follow-up of 21 months. At long-term follow-up, of 38 patients, 23 were seizure-free (Engel class I), 2 had improved seizures (Engel class II), 6 had poor seizure control (Engel class III/IV), and 7 died. CONCLUSIONS: Excision of insular high-grade gliomas is safe and results in excellent postoperative seizure control.

The Dilemma of Multifocality in Insular Tumors: Multicentricity versus Metastasis.

BACKGROUND AND PURPOSE: Multifocality and metastasis from insular glioma are extremely rare. Pathological insights and elaboration of the clinical course of this condition will contribute to their better understanding. MATERIALS AND METHODS: Among 123 consecutively operated insular gliomas, 5 patients (4.2%) presented with a multifocal tumor. The clinico-radiological, histo-molecular, and treatment outcomes were noted and compared with the unifocal insular glioma cohort. RESULTS: Among the five patients, all were males and involved the right insular lobe. Three patients presented with synchronous tumors, while two patients developed metachronous multifocal tumors. The histology of the insular tumor was Grade I glioma in 1, Grade II astrocytoma with p53 mutation in 2, and anaplastic astrocytoma and glioblastoma in one patient each. Histological confirmation of the second lesion was performed in two patients, showing the same histology of the insular tumor. Interconnection between the tumors was apparent through cerebrospinal fluid pathways in four patients, while no such connection could be established in one patient. Barring the patient of Grade I glioma, the rest of the patients died within months of the diagnosis. CONCLUSION: Multifocal insular glioma is rare and probably represents a biologically more aggressive tumor. Insular glioma that touches the ventricle appears a common denominator for multifocality. True multicentricity is rare. The prognosis in insular glioma with multifocality is poor in non-Grade I gliomas.