Insular Low-grade Glioma Research Articles

Hyperechoic Area Under Insular Gliomas: A Potentially Hazardous Intraoperative Ultrasound Artifact

Intraoperative ultrasound (IOUS) images can be distorted by various artifacts. During surgeries for insular low-grade gliomas (LGGs), we repeatedly observed a distinct hyperechoic artifact adjacent to medial tumor borders, localized in brain regions with normal appearance on magnetic resonance imaging (MRI) that has not been reported before. We retrospectively evaluated saved 3-dimensional (3D) IOUS images of 20 patients harboring insular LGGs. Twelve patients were operated on between 2010 and 2015 using an older navigated 3D IOUS system. Additionally, 3D-IOUS images of 8 patients operated on between 2021 and 2023 using a new high-end 3D-IOUS system were evaluated. The investigated region was the area under medial tumor borders, which were defined using preoperative MRI. In 17 out of 20 cases (85%), a distinct hyperechoic area adjacent to medial tumor borders localized in brain regions with normal appearance on preoperative MRI was found; in the remaining 3 cases the saved images were suboptimal and did not allow evaluation of the area under the medial tumor borders. Although the causes of this bright artifact are unclear, we can hypothesize that the reverberation in between different parallel layers of white and gray matter localized under the insula could play a role in its appearance. Importantly, as this hyperechoic area was depicted already before any tumor resection, it may lead to erroneous conclusion that the tumor spreads more medially. Potential resection in this region may cause significant neurologic sequelae.

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

ObjectiveOur 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. MethodsWe 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. ResultsIn 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). ConclusionsWe 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.

Recurrent insular low-grade gliomas: factors guiding the decision to reoperate.

Reoperation has been established as an effective therapeutic strategy in recurrent diffuse low-grade gliomas (LGGs). Insular gliomas represent a specific surgical challenge because of the surrounding vascular and functional structures. The aim of this study was to investigate the main clinicoradiological factors guiding the decision to reoperate on recurrent insular LGGs (ILGGs). In this retrospective consecutive series, the authors screened all patients operated on for an ILGG in their institution who further presented with a tumor regrowth without the development of contrast enhancement. They compared patients who were subsequently offered a reoperation under awake mapping at recurrence or who underwent reoperation after adjuvant treatment had reduced the volume of the initial tumor recurrence (with a proven pathological diagnosis of LGG after the second surgery) to patients who were not selected for a reoperation. The first group (reoperated group; n = 20) included all recurrent ILGG patients who underwent second resection, and the second group (nonreoperated group; n = 60) included patients who did not undergo reoperation but underwent adjuvant oncological treatment. Factors significantly associated with reoperation were extent of resection (EOR) at first surgery (91.9% vs 89.7%, p = 0.014), residual tumor volume (9.5 ± 7.1 mL [range 0-30 mL] vs 6.3 ± 7.3 mL [range 0-30 mL], p = 0.02) at first surgery and left temporopolar infiltration at the time of tumor recurrence (Liebermeister statistical analysis, 4293 voxels survived false discovery rate correction with p < 0.05; maximal z-statistic = 6.50). Infiltration of the anterior perforated substance at tumor recurrence was significantly anticorrelated to reoperation (179 voxels survived false discovery rate correction with p < 0.05; minimal z-statistic = -4.33). The mean EOR was 83.7% at reoperation with a 90% survival rate at last follow-up (9.3 ± 3.8 years), low postsurgical morbidity (Karnofsky Performance Status score ≥ 80 in 95% of patients), a high rate of postoperative professional resumption (95%), and seizure control in 57.1% of patients. In selected patients with recurrent ILGG without radiographic evidence of malignant transformation, reoperation with intraoperative awake mapping is associated with favorable oncological outcomes and a low postsurgical morbidity. A greater EOR and a lower residual tumor volume at first surgery were significantly associated with reoperation. Patients who benefited from a second surgery typically had a recurrent pattern within cortical areas (such as the temporopolar region), while other patients typically presented with a deeper infiltrative pattern within the anterior perforated substance and the surrounding white matter pathways. Such original findings may be helpful to select the optimal indications of reoperation in recurrent ILGG.

Challenges in the Diagnosis and Management of Low-Grade Gliomas

Low-grade gliomas are clinically challenging entities. Patients with these tumors tend to be relatively young at presentation, and lesions are often incidental findings or are identified because the patient presents with a seizure. Rapidly emerging and evolving molecular classifications of gliomas have influenced treatment paradigms. Importantly, low-grade gliomas can be classified on the basis of IDH mutation status, whereby low-grade astrocytomas harbor the IDH mutation, while oligodendrogliomas are defined by both IDH mutant status and 1p/19q co-deletion. Given the importance of molecular classification for diagnosis, treatment planning, and prognostication, tissue samples are necessary for proper management. Literature supports improved overall survival and outcomes with increased extent of resection for low-grade glioma. Awake craniotomies and resection of insular low-grade gliomas both have been demonstrated as safe and improve outcomes for patients with lesions located in eloquent areas. Given the younger age at diagnosis of these lesions compared with higher-grade gliomas, fertility, fertility preservation, and potential malignant transformation should be discussed with patients of childbearing age.

Transopercular Insular Approach, Overcoming the Training Curve Using a Cadaveric Simulation Model: 2-Dimensional Operative Video.

Transopercular approach to the insula is indicated for resection of insular low-grade gliomas, particularly for Yasargil's 3B, 5A, and 5B types. Nevertheless, the infrequent location and its challenging approach make it difficult to master the surgery. Consequently, a realistic laboratory training model might help to acquire key surgical skills. In this video, we describe a cadaveric-based model simulating the resection of a temporo-insular low-grade glioma. Kingler's fixation technique was used to fix the cadaver head before injecting red and blue colorants for a realistic vascular appearance. Hemisphere was frozen for white matter tract dissection. Tractography and intraoperative eloquent areas were extrapolated from a glioma patient by using a neuronavigation system. Then, a fronto-temporal craniotomy was performed through a question mark incision, exposing from inferior temporal gyrus up to middle frontal gyrus. After cortical anatomic landmark identification, eloquent areas were extrapolated creating a simulated functional cortical map. Then, transopercular noneloquent frontal and temporal corticectomies were performed, followed by subpial resection. Detailed identification of Sylvian vessels and insular cortex was demonstrated. Anatomic resection limits were exposed, and implicated white matter bundles, uncinate and fronto-occipital fascicles, were identified running through the temporal isthmus. Finally, a temporo-mesial resection was performed. In summary, this model provides a simple, cost-effective, and very realistic simulation of a transopercular approach to the insula, allowing the development of surgical skills needed to treat insular tumors in a safe environment. Besides, the integration of simulated navigation has proven useful in better understanding the complex white matter anatomy involved. Cadaver donation, subject or relatives, includes full consent for publication of the images. For the purpose of this video, no ethics committee approval was needed. Images correspond to a cadaver head donation. Cadaver donation, subject or relatives, includes full consent for any scientific purposes involving the corpse. The consent includes image or video recording. Regarding the intraoperative surgical video and tractography, the patient gave written consent for scientific divulgation prior to surgery.

Seizure Outcome After Surgery for Insular High-Grade Glioma

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. 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. 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. Excision of insular high-grade gliomas is safe and results in excellent postoperative seizure control.

Recovery of major cognitive deficits following awake surgery for insular glioma: a case report

Background: Resection of insular tumours utilising modern neurosurgical techniques has become commonplace since its safety and reduced morbidity was first established. Interest has grown in the cognitive consequences of insula neurosurgery and studies have largely shown postoperative stability or minor decline. Major or widespread improvements in cognitive functioning following resection of insular tumours have not previously been reported. Case description: A 34-year-old, left-handed man with a right insular low-grade glioma (LGG) presented with seizures, nausea, altered sensation, poor balance and extensive cognitive decline. Comprehensive neuropsychological assessment highlighted a striking left hemispatial neglect and impairments in attention, working memory, verbal learning and fluency. During an awake craniotomy with functional cortical mapping, he reported intraoperative improvements in hand function and processing speed. Resolution of the neglect and significant improvements in cognition, mood and functioning were observed at follow-up and sustained over several years. Conclusions: This case highlights that right insular LGGs can cause significant cognitive and functional deficits and that neurosurgery has the potential to alleviate these difficulties to an extent beyond those documented in the extant literature.

Surgery in high-grade insular tumors: Oncological and seizure outcomes from 41 consecutive patients

Background:Insular high-grade gliomas are uncommon and constitute approximately 10% of all intracranial high-grade gliomas. Several publications in the recent years have thrown substantial light in the understanding of insular low-grade gliomas. However, there is a paucity of information concerning the spectrum of high-grade lesions affecting the insula, the mode of presentation vis-à-vis low-grade gliomas, and the survival rates to modern therapy.Aims and Objectives:We aim to highlight various clinical patterns, histo-pathological spectrum and the survival rates in patients with high-grade insular lesions. Also, we explore the factors that govern favourable outcomes.Materials and Methods:A retrospective study of 41 patients operated for high-grade insular tumors at our institute between March 2010 to December 2018 was done to evaluate the clinico-radiological features, surgical nuances, survival rates and seizure outcomes.Results:Raised intracranial pressure was the most frequent clinical presentation (n=28/41, 68.3%). Nearly 60% of the patients (n=25) had involvement of all four Berger-Sanai zones. The high-grade tumors encountered in our series were: glioblastoma (n=15), gliosarcoma (n=3), and embryonal tumor, not otherwise specified in 3 patients, while 21 patients had grade 3 astrocytoma. 33 out of 41 patients (80.5%) in our study showed excellent seizure control (ILAE grade 1A) at follow-up. Clinical presentation with seizures (P = 0.01, HR=0.3), WHO grade IV histopathology (P = 0.04, HR=3.7) and development of recurrence (P = 0.05, HR=5.5) were found to be independent predictors of OS.Conclusion:Insular high-grade gliomas are commoner than thought and nearly half of these are grade IV tumors (51%). A presentation with seizures may indicate precursor low-grade gliomas and portend a better survival. A maximum “safe” surgical resection, keeping the postoperative quality of life in mind, should be the goal.

Molecular profiles for insular low-grade gliomas with putamen involvement.

The newly proposed putamen classification system shows good prognostic value in patients with insular LGGs, yet no study towards the molecular profiles of putamen involved LGGs has been proposed. Clinical information and imaging data of patients diagnosed with insular low-grade gliomas were collected retrospectively. Genetic information of the 34 tumors was assessed using RNA-sequencing. Gene set enrichment analysis was further performed to identify the genes showing differential expression between putamen-involved tumors and putamen non-involved tumors. The level of Ki-67 expression was also evaluated. There were 843 genes identified to be differentially expressed between putamen-involved and non-involved gliomas. Specifically, Gene set enrichment analysis discovered 13 Kyoto Encyclopedia of Genes and Genomes pathways and 37 Gene Ontology Biological Process term were upregulated in putamen-involved low-grade glioma cells. The enriched GO sets with the highest gene counts included cell cycle (42 genes), mitotic cell cycle (24 genes), and cell division (19 genes). Furthermore, high expression of Ki-67 was associated with putamen involvement in insular gliomas. There is clear genetic variation between putamen-involved and non-involved insular low-grade gliomas. The differential expression of genes related to the processes of cell proliferation, cell migration, or DNA repair may lead to putamen involvement. The findings suggest that among the two subtypes, putamen-involved insular low-grade gliomas have higher malignancy, and the clinical treatment towards the putamen-involved insular low-grade gliomas should be more active.

Awake Craniotomy for Left Insular Low-Grade Glioma Removal on a Patient with Learning Disabilities

Introduction Low-grade gliomas (LGG) are slow-growing primary brain tumors in adults, with high tropism for eloquent areas. Standard approach in treatment of LGG is awake craniotomy with intraoperative cortical mapping — a method which is usually used on adult and fully cooperative patients. Case Report We present the case of a patient with learning disabilities (PLD) who was operated for left insular LGG awake craniotomy, and intraoperative cortical mapping were performed and the tumor was gross totally removed. Conclusion Awake surgery for left insular LGG removal is challenging; however, it can be performed safely and successfully on PLD.

Putamen involvement and survival outcomes in patients with insular low-grade gliomas.

OBJECTIVE Insular glioma has a unique origin and biological behavior; however, the associations between its anatomical features and prognosis have not been well established. The object of this study was to propose a classification system of insular low-grade gliomas based on preoperative MRI findings and to assess the system's association with survival outcome. METHODS A total of 211 consecutively collected patients diagnosed with low-grade insular gliomas was analyzed. All patients were classified according to whether tumor involved the putamen on MR images. The prognostic role of this novel putaminal classification, as well as that of Yaşargil's classification, was examined using multivariate analyses. RESULTS Ninety-nine cases (46.9%) of insular gliomas involved the putamen. Those tumors involving the putamen, as compared with nonputaminal tumors, were larger (p < 0.001), less likely to be associated with a history of seizures (p = 0.04), more likely to have wild-type IDH1 (p = 0.003), and less likely to be totally removed (p = 0.02). Significant favorable predictors of overall survival on univariate analysis included a high preoperative Karnofsky Performance Scale score (p = 0.02), a history of seizures (p = 0.04), gross-total resection (p = 0.006), nonputaminal tumors (p < 0.001), and an IDH1 mutation (p < 0.001). On multivariate analysis, extent of resection (p = 0.035), putamen classification (p = 0.014), and IDH1 mutation (p = 0.026) were independent predictors of overall survival. No prognostic role was found for Yaşargil's classification. CONCLUSIONS The current study's findings suggest that the putamen classification is an independent predictor of survival outcome in patients with insular low-grade gliomas. This newly proposed classification allows preoperative survival prediction for patients with insular gliomas.

Visualization of lenticulostriate arteries during insular low-grade glioma surgeries by navigated 3D ultrasound power Doppler: technical note.

OBJECTIVE Resection of insular gliomas is challenging. In cases of intraoperative injury to the lenticulostriate arteries (LSAs), the usual result is a dense hemiplegia. LSAs are usually localized just behind the medial tumor border but they can also be encased by the tumor. Thus, exact localization of these perforators is important. However, intraoperative localization of LSAs using conventional neuronavigation can be difficult due to brain shift. In this paper, the authors present a novel method of intraoperative LSA visualization by navigated 3D ultrasound (3DUS) power Doppler. This technique enables almost real-time imaging of LSAs and evaluation of their shift during insular tumor resections. METHODS Six patients harboring insular Grade II gliomas were consecutively operated on at the Department of Neurosurgery in Bratislava using visualization of LSAs by navigated 3DUS power Doppler. In all cases, the 3DUS data were repeatedly updated to compensate for the brain shift and display the actual position of LSAs and residual tumor. RESULTS Successful visualization of LSAs was achieved in all cases. During all surgeries, the distance between the bottom of the resection cavity and LSAs could be accurately evaluated; in all tumors the resection approached the LSAs and only a minimal amount of tissue covering these perforators was intentionally left in place to avoid injury to them. CONCLUSIONS Visualization of LSAs by navigated 3DUS power Doppler is a useful tool that may help to prevent injury of LSAs during removal of insular low-grade gliomas. However, reliability of this method has to be carefully evaluated in further studies.

Awake Craniotomy and Intraoperative MRI for Maximal Safe Resection in a Case of an Extensive Left Frontal and Insular Low-grade Glioma: 3-Dimensional Operative Video.

Awake Craniotomy and Intraoperative MRI for Maximal Safe Resection in a Case of an Extensive Left Frontal and Insular Low-grade Glioma: 3-Dimensional Operative Video.

Subgroup characteristics of insular low-grade glioma based on clinical and molecular analysis of 42 cases.

Although the classification of insular glioma has been established based on the anatomical location in order to facilitate personalized surgical resection, the diagnosis based on anatomical and functional characteristics becomes more complex when insular tumors extend into either the frontobasal brain region and/or the temporal lobe, as part of the limbic system. Moreover, prognosis of insular tumor resection is still controversial. Further analysis of subgroup characteristics of insular grade II gliomas based on clinical and molecular analysis is required to reliably determine patients' survival rates. In this retrospective study 20 purely insular grade II gliomas patients and 22 paralimbic grade II gliomas that involved frontal and/or temporal lobes were compared with regard to epidemiological and clinical characteristics. The molecular profiles including Isocitrate dehydrogenase 1 (IDH1), telomerase reverse transcriptase (TERT) promoter, and P53 mutations, 1p19q co-deletion were analyzed, and microRNA profiles were assessed by microarray and bioinformatics analysis. Purely insular grade II gliomas displayed a high frequency of IDH1 mutations with favorable outcome. IDH1 mutated paralimbic glioma shared many parameters with the purely insular glioma in respect to growth patterns, survival, and microRNA profile, but differed significantly from the IDH1 wild type paralimbic gliomas. Our findings suggest that IDH1 mutations can define subpopulations of insular gliomas with distinct disease entities regardless of tumor extension patterns. These findings could be useful to develop a customized treatment strategy for insular glioma patients.

Second Surgery in Insular Low-Grade Gliomas.

Background. Given the technical difficulties, a limited number of works have been published on insular gliomas surgery and risk factors for tumor recurrence (TR) are poorly documented. Objective. The aim of the study was to determine TR in adult patients with initial diagnosis of insular Low-Grade Gliomas (LGGs) that subsequently underwent second surgery. Methods. A consecutive series of 53 patients with insular LGGs was retrospectively reviewed; 23 patients had two operations for TR. Results. At the time of second surgery, almost half of the patients had experienced progression into high-grade gliomas (HGGs). Univariate analysis showed that TR is influenced by the following: extent of resection (EOR) (P < 0.002), ΔVT2T1 value (P < 0.001), histological diagnosis of oligodendroglioma (P = 0.017), and mutation of IDH1 (P = 0.022). The multivariate analysis showed that EOR at first surgery was the independent predictor for TR (P < 0.001). Conclusions. In patients with insular LGG the EOR at first surgery represents the major predictive factor for TR. At time of TR, more than 50% of cases had progressed in HGG, raising the question of the oncological management after the first surgery.

P20 * VARIATIONS IN MANAGEMENT OF LOW GRADE GLIOMAS ACROSS UK NEUROSURGICAL UNITS

INTRODUCTION: Low grade gliomas (LGG) are slow growing tumours, with the potential of transforming into aggressive high grade gliomas. Treatment of LGG must balance risk of malignant transformation against morbidity of early aggressive treatment. We evaluated the variation in management of low grade gliomas in the UK. METHOD: A survey was sent to all adult UK neurosurgery units, addressing surgical technology, treatment choice and surveillance. 23 units participated (82% participation rate). RESULTS: All LGG patients are discussed in an MDT meeting at initial presentation. 11 units manage patients in neurosurgical oncology clinics, and 6 units had dedicated LGG clinics. Others manage patients in general neurosurgical (3), combined (2) and oncology (1) clinics. The majority of centres use intra-operative ultrasound (20) and functional MRI (19) for motor and language mapping. 11 units use intra-operative EMG. Post-operative surveillance imaging intervals range from 3 to 12 months. Most units have multimodal MRI to detect tumour transformation, but do not always use them. Only 5 units use volumetric changes and 5 use PET imaging. Two clinical scenarios were also given: for a peripheral LGG, all units would consider resection followed by surveillance. Variable responses were given for an insular LGG: 9 would manage only with active surveillance, 6 would consider resection followed by surveillance. The rest choose to biopsy, followed by surveillance (4) or radiotherapy (4). CONCLUSION: This study demonstrates variable management of LGG across the UK, particularly surveillance intervals and of tumours in eloquent areas. More research to stratify transformation risk can help guide optimal treatment.

Surgery for insular low-grade glioma: predictors of postoperative seizure outcome

Although a number of recent studies on the surgical treatment of insular low-grade glioma (LGG) have demonstrated that aggressive resection leads to increased overall patient survival and decreased malignant progression, less attention has been given to the results with respect to tumor-related epilepsy. The aim of this investigation was to evaluate the impact of volumetric, histological, and intraoperative neurophysiological factors on seizure outcome in patients with insular LGG. The authors evaluated predictors of seizure outcome with special emphasis on both the extent of tumor resection (EOR) and the tumor's infiltrative pattern quantified by computing the difference between the preoperative T2- and T1-weighted MR images (ΔVT2T1) in 52 patients with preoperative drug-resistant epilepsy. The 12-month postoperative seizure outcome (Engel class) was as follows: seizure free (Class I), 67.31%; rare seizures (Class II), 7.69%; meaningful seizure improvement (Class III), 15.38%; and no improvement or worsening (Class IV), 9.62%. Poor seizure control was more common in patients with a longer preoperative seizure history (p < 0.002) and higher frequency of seizures (p = 0.008). Better seizure control was achieved in cases with EOR ≥ 90% (p < 0.001) and ΔVT2T1 < 30 cm(3) (p < 0.001). In the final model, ΔVT2T1 proved to be the strongest independent predictor of seizure outcome in insular LGG patients (p < 0.0001). No or little postoperative seizure improvement occurs mainly in cases with a prevalent infiltrative tumor growth pattern, expressed by high ΔVT2T1 values, which consequently reflects a smaller EOR.

Insular glioma resection: assessment of patient morbidity, survival, and tumor progression

Insular gliomas remain surgically challenging cases due to complex anatomy, including surrounding vasculature and the relationship to functional structures. To define the morbidity profile associated with aggressive insular glioma removal as well as its impact on long-term outcome, the authors retrospectively evaluated the extent of resection (EOR) in the context of this complex anatomy and function and assessed its role in determining disease progression, malignant transformation, and, ultimately, patient survival. The study population included adults who had undergone initial or repeat resection of insular gliomas of all grades. Tumor location was identified according to a proposed quadrant-style classification (Zones I-IV) of the insula. Low- and high-grade gliomas were volumetrically analyzed using FLAIR and contrast-enhanced T1-weighted MR imaging, respectively. One hundred fifteen procedures involving 104 patients with insular gliomas were identified. Patients presented with low-grade gliomas (LGGs) in 70 cases (60%) and high-grade gliomas (HGGs) in 45 (40%). Zone I (anterior-superior) was the most common site within the insula (40 patients [39%]), followed by Zone I+IV (anterior-superior + anterior-inferior; 26 patients [25%]). The median EOR was 82% (range 31-100%) for low-grade lesions and 81% (range 47-100%) for high-grade lesions. Zone I was associated with the highest median EOR (86%), and among all lesion grades, the insular quadrant anatomy was predictive of the EOR (p = 0.0313). Overall, there were 16 deaths (15%) during a median follow-up of 4.2 years. There were no surgery-related deaths, and new, permanent postoperative deficits were noted in 6 patients (6%). Among LGGs, tumor progression and malignant transformation were identified in 20 (29%) and 14 cases (20%), respectively. Among HGGs, progression was identified in 16 cases (36%). Patients with LGGs resected >or= 90% had a 5-year overall survival (OS) rate of 100%, whereas those with lesions resected < 90% had a 5-year OS rate of 84%. Patients with HGGs resected >or= 90% had a 2-year OS rate of 91%; when the EOR was < 90%, the 2-year OS rate was 75%. The EOR was predictive of OS both in cases of LGGs (hazard ratio [HR] 0.955, 95% CI 0.921-0.992, p = 0.017) and HGGs (HR 0.955, 95% CI 0.918-0.994, p = 0.024). Progression-free survival (PFS) was also predicted by the EOR in both LGGs (HR 0.973, 95% CI 0.948-0.998, p = 0.0414) and HGGs (HR 0.958, 95% CI 0.919-0.999, p = 0.0475). Interestingly, among patients with LGGs, malignant progression was also significantly associated with a lower EOR (HR 0.968, 95% CI 0.393-0.998, p = 0.0369). Aggressive resection of insular gliomas of all grades can be accomplished with an acceptable morbidity profile and is predictive of improved OS and PFS. Among insular LGGs, a greater EOR is also associated with longer malignant PFS. Data in this study also suggest that insular gliomas generally follow a more indolent course than similar lesions in other brain regions.

The insular lobe and brain plasticity: Lessons from tumor surgery

Objectives Despite recent literature supporting the likely role of the insula in many functions, the actual participation of this multimodal lobe in the brain functioning remains unclear, i.e. has the insula an essential or compensable role? Patients and methods We surgically resected an insular low-grade glioma, using intraoperative electrical stimulation, in 42 patients who experienced seizures, but who presented no or only a slight neurological deficit. Surgery was performed under local anesthesia in patients with a lesion in the dominant hemisphere. The resection was systematically stopped according to cortico-subcortical functional boundaries. Results Intraoperative electrical mapping induced language disturbances, pain and vertigo, but no other side effects were observed. Post-operatively, the patients experienced a transient hemiparesis in 21 cases, language disorders in 10 cases, an athymhormic syndrome in 7 cases, a Foix-Chavany-Marie syndrome in 3 cases, and micturition disturbances in one case. Despite this immediate post-surgical worsening, all the patients recovered their preoperative neurological status within 3 months, except in three cases due to a deep stroke. Conclusion These results show that the insula, a complex associative multimodal structure poorly studied until now, can be functionally compensated. Such a plastic potential may have important fundamental and clinical implications, in particular in the field of oncological neurosurgery.

Medically intractable epilepsy from insular low-grade gliomas: improvement after an extended lesionectomy.

With the aim to better evaluate the role of the insula in seizures and the therapeutic implications, we analyzed the rate of insular low-grade gliomas (LGG) presenting with medically refractory epilepsy, detailed their ictal symptoms, and described the epileptological results following their surgical resection. Eleven patients (8 men, 3 women, mean age: 35 years) harboring an insular LGG generating intractable seizures, underwent tumor removal and perilesional opercular cortex resection (lesionectomy "plus") using intraoperative functional electrical mapping, combined with ultrasonography and/or neuronavigation. Despite the occurrence of five postoperative deficits, the patients recovered in all cases. The epileptological results showed improvement in all cases: 9 Engel's Class I (82%), 1 Class II and 1 Class III. Ten lesionectomies were total [3] or subtotal [7], while one resection was partial (the patient in Engel's III). The high rate of pharmacologically intractable seizures associated with insular LGG, and the favorable epilepsy outcome following surgical resection of these tumors seemingly indicate that the insular cortex itself may induce chronic seizures when injured. These results suggest, taking account of the technical surgical progress allowing now to minimize the morbidity after surgery in this region, that there is another indication than the sole oncological reason for surgery in patients with diffuse insular glioma -- even if total tumor removal is not systematically possible.