Hemispheric functional organization, as revealed by naturalistic neuroimaging, in pediatric epilepsy patients with cortical resections.

Functional changes in the pediatric brain following neural injuries attest to remarkable feats of plasticity. Investigations of the neurobiological mechanisms that underlie this plasticity have largely focused on activation in the penumbra of the lesion or in contralesional, homotopic regions. Here, we adopt a whole-brain approach to evaluate the plasticity of the cortex in patients with large unilateral cortical resections due to drug-resistant childhood epilepsy. We compared the functional connectivity (FC) in patients' preserved hemisphere with the corresponding hemisphere of matched controls as they viewed and listened to a movie excerpt in a functional magnetic resonance imaging (fMRI) scanner. The preserved hemisphere was segmented into 180 and 200 parcels using two different anatomical atlases. We calculated all pairwise multivariate statistical dependencies between parcels, or parcel edges, and between 22 and 7 larger-scale functional networks, or network edges, aggregated from the smaller parcel edges. Both the left and right hemisphere-preserved patient groups had widespread reductions in FC relative to matched controls, particularly for within-network edges. A case series analysis further uncovered subclusters of patients with distinctive edgewise changes relative to controls, illustrating individual postoperative connectivity profiles. The large-scale differences in networks of the preserved hemisphere potentially reflect plasticity in the service of maintained and/or retained cognitive function.

Middle third falcine meningiomas-surgical nuances for cortical venous preservation.

PURPOSE: To improve postoperative outcome in middle third falcine meningiomas by cortical venous preservation. BACKGROUND: Falcine meningiomas arise from the falx and do not involve the superior sagittal sinus (SSS). Their complete resection is often associated with the risk of venous infarction in the eloquent cortex due to overlying superficial cortical veins on the tumors. METHOD: We report one case of middle third falcine meningioma, where we used the posterior interhemispheric corridor for tumor approach. CONCLUSION: Use of the posterior interhemispheric approach, carefully raised bone flap, along with sharp dissection and vein reinforcement using fibrin glue can help to preserve the cortical veins while resecting the falcine meningiomas.

Profiling functional networks identify activation of corticostriatal connectivity in ET patients after MRgFUS thalamotomy.

BACKGROUND: MR-guided focused ultrasound (MRgFUS) thalamotomy is a novel and effective treatment for medication-refractory tremor in essential tremor (ET), but how the brain responds to this deliberate lesion is not clear. OBJECTIVE: The current study aimed to evaluate the immediate and longitudinal alterations of functional networks after MRgFUS thalamotomy. METHODS: We retrospectively obtained preoperative and postoperative 30-day, 90-day, and 180-day data of 31 ET patients subjected with MRgFUS thalamotomy from 2018 to 2020. Their archived resting-state functional MRI data were used for functional network comparison as well as graph-theory metrics analysis. Both partial least squares (PLS) regression and linear regression were conducted to associate functional features to tremor symptoms. RESULTS: MRgFUS thalamotomy dramatically abolished tremors, while global functional network only sustained immediate fluctuation within one week after the surgery. Network-based statistics have identified a long-term enhanced corticostriatal subnetwork by comparison between 180-day and preoperative data (P = 0.019). Within this subnetwork, network degree, global efficiency and transitivity were significantly recovered in ET patients right after MRgFUS thalamotomy compared to the pre-operative timepoint (P < 0.05), as well as hemisphere lateralization (P < 0.001). The PLS main component significantly accounted for 33.68 % and 34.16 % of the total variances of hand tremor score and clinical rating scale for tremor (CRST)-total score (P = 0.037 and 0.027). Network transitivity of this subnetwork could serve as a reliable biomarker for hand tremor score control prediction at 180-day after the surgery (ß = 2.94, P = 0.03). CONCLUSION: MRgFUS thalamotomy promoted corticostriatal connectivity activation correlated with tremor improvement in ET patient after MRgFUS thalamotomy.

Cortico-cortical evoked potentials of language tracts in minimally invasive glioma surgery guided by Penfield stimulation.

OBJECTIVE: We investigated the feasibility of recording cortico-cortical evoked potentials (CCEPs) in patients with low- and high-grade glioma. We compared CCEPs during awake and asleep surgery, as well as those stimulated from the functional Broca area and recorded from the functional Wernicke area (BtW), and vice versa (WtB). We also analyzed CCEP properties according to tumor location, histopathology, and aphasia. METHODS: We included 20 patients who underwent minimally invasive surgery in an asleep-awake-asleep setting. Strip electrode placement was guided by classical Penfield stimulation of positive language sites and fiber tracking of the arcuate fascicle. CCEPs were elicited with alternating monophasic single pulses of 1.1 Hz frequency and recorded as averaged signals. Intraoperatively, there was no post-processing of the signal. RESULTS: Ninety-seven CCEPs from 19 patients were analyzed. There was no significant difference in CCEP properties when comparing awake versus asleep, nor BtW versus WtB. CCEP amplitude and latency were affected by tumor location and histopathology. CCEP features after tumor resection correlated with short- and long-term postoperative aphasia. CONCLUSION: CCEP recordings are feasible during minimally invasive surgery. CCEPs might be surrogate markers for altered connectivity of the language tracts. SIGNIFICANCE: This study may guide the incorporation of CCEPs into intraoperative neurophysiological monitoring.

Widening the Operative Corridor-Evaluating the Transcortical Approach to Giant Falcine Meningiomas.

BACKGROUND: Giant falcine meningiomas are surgically complex as they are deep in location, concealed by normal brain parenchyma, in close proximity to various neurovascular structures, and frequently involve the falx bilaterally. Although classically accessed using a bifrontal craniotomy and interhemispheric approach, little data exist on alternative operative corridors for these challenging tumors. We evaluated perioperative and long-term outcomes in patients undergoing transcortical resection of giant bilateral falcine meningiomas. METHODS: From 2013 to 2022, fourteen patients with giant bilateral falcine meningiomas treated via a transcortical approach at our institution were identified. Perioperative and long-term outcomes were evaluated to determine predictors of adverse events. Corticectomy depth was also analyzed to determine if it correlated with increased postoperative seizure rates. RESULTS: 57.1% of cases were WHO grade 2 meningiomas. Average tumor volume was 77.8 ± 46.5 cm3 and near/gross total resection was achieved in 78.6% of patients. No patient developed a venous infarct or had seizures in the 6 months after surgery. Average corticectomy depth was 0.83 ± 0.71 cm and increasing corticectomy depth did not correlate with higher risk of postoperative seizures (P = 0.44). Increasing extent of tumor resection correlated with lower tumor grade (P = 0.011) and only 1 patient required repeat resection during a median follow-period of 24.9 months. CONCLUSIONS: The transcortical approach is a safe alternative corridor for accessing giant, falcine meningiomas, and postoperative seizures were not found to correlate with increasing corticectomy depth. Further prospective studies are necessary to determine the best approach to these surgically complex lesions.

A taxonomy for superficial cerebral cavernous malformations: subtypes of cortical and subcortical lesions.

OBJECTIVE: A taxonomy for superficial cerebral cavernous malformations (CMs), those based cortically in gyral gray matter or subcortically in underlying white matter, is proposed to build on the comprehensive, systematic characterization of CMs in the entire brain. METHODS: Patients with superficial cerebral CMs were retrospectively analyzed from a consecutive surgical series between November 2008 and June 2021 at the authors' center. Superficial cerebral CMs were categorized into 4 subtypes based on their cortical location or, if subcortical, proximity to the nearest cerebral surface: convexity, medial, basal, and sylvian. Lobar location was also included for subtyping: frontal, temporal, parietal, and occipital. RESULTS: A total of 362 CMs were resected in 346 patients. CM subtypes were as follows: 132 (36.5%) convexity, 78 (21.5%) medial, 72 (19.9%) basal, and 80 (22.1%) sylvian. Frontal CMs were most common (155 [42.8%]), followed by parietal (89 [24.6%]), temporal (87 [24.0%]), and occipital (31 [8.6%]). Of all CMs, 302 (83.4%) were cortical and 60 (16.6%) were subcortical. The mean subcortical depth of deep lesions was 2.97 cm, and the mean lesion volume was 4.68 cm3. Overall, 228 lesions (63.0%) were resected through a transgyral approach, and 134 (37.0%) were resected through a transsulcal approach. Good outcomes (modified Rankin Scale [mRS] score ≤ 2) were observed in 314 patients (86.7%) and poor outcomes (mRS score > 2) in 25 patients (6.9%), and 23 patients (6.4%) were lost to late follow-up (mean follow-up duration 11.5 months). Relative outcomes were good (unchanged or improved mRS score) in 327 patients (90.3%) and poor (worse or died) in 35 patients (9.7%). CONCLUSIONS: Superficial cerebral CMs were resected through a gyrus or sulcus to open the subarachnoid dissection corridors, traversing the full extent of sulci to deepen the approach and minimize tissue transgression. Transgyral dissection avoids associated arteries but is inherently transgressive, whereas transsulcal dissection preserves cortical tissue and may reduce morbidity. Superficial cerebral CMs occupy the largest territory of the 7 types, and the size and surface complexity of the cerebrum make taxonomic subtyping valuable for clear anatomical description.

Contralateral Interhemispheric Transfalcine Approach to the Basal Ganglia.

The contralateral interhemispheric approach provides a robust path into the mesial frontal lobe and basal ganglia structures.1 The use of gravity to retract the dominant frontal lobe allows the surgeon to avoid injury caused by exposure of the dominant hemisphere. The transfalcine corridor, however, is long and often not well illuminated, necessitating the use of lighted instruments. Within the path of approach lie the anterior cerebral arteries, which must be carefully dissected and preserved. Upon opening the falx, the entire mesial frontal lobe and deep basal ganglia structures can be readily accessed. Herein, we present a patient with familial cerebral cavernous malformation-1 syndrome who presented after an acute hemorrhage from a deep basal ganglia cerebral cavernous malformation (Video 1). The patient consented to the procedure. The patient was hemiparetic and aphasic, likely secondary to mass effect from the bleed. The lesion was approached from a contralateral interhemispheric approach and removed completely. The patient's examination improved with removal of the mass lesion. This case demonstrates the utility of this approach for accessing deep corridors within the cerebral cortices.

Visualization of the lenticulostriate arteries, long insular arteries, and long medullary arteries on intra-arterial computed tomography angiography with ultrahigh resolution in patients with glioma.

PURPOSE: The anatomical association between the lesion and the perforating arteries supplying the pyramidal tract in insulo-opercular glioma resection should be evaluated. This study reported a novel method combining the intra-arterial administration of contrast medium and ultrahigh-resolution computed tomography angiography (UHR-IA-CTA) for visualizing the lenticulostriate arteries (LSAs), long insular arteries (LIAs), and long medullary arteries (LMAs) that supply the pyramidal tract in two patients with insulo-opercular glioma. METHODS: This method was performed by introducing a catheter to the cervical segment of the internal carotid artery. The infusion rate was set at 3 mL/s for 3 s, and the delay time from injection to scanning was determined based on the time-to-peak on angiography. On 2- and 20-mm-thick UHR-IA-CTA slab images and fusion with magnetic resonance images, the anatomical associations between the perforating arteries and the tumor and pyramidal tract were evaluated. RESULTS: This novel method clearly showed the relationship between the perforators that supply the pyramidal tract and tumor. It showed that LIAs and LMAs were far from the lesion but that the proximal LSAs were involved in both cases. Based on these results, subtotal resection was achieved without complications caused by injury of perforators. CONCLUSION: UHR-IA-CTA can be used to visualize the LSAs, LIAs, and LMAs clearly and provide useful preoperative information for insulo-opercular glioma resection.

Central quadrantotomy for intractable childhood epilepsy: operative technique and functional neuroanatomy.

Refractory subhemispheric epilepsy has been traditionally treated by resection. The last few decades have seen the emergence of disconnective techniques, for both hemispheric and subhemispheric disease. The aim of this study was to describe the technique for a disconnective surgery for large epileptogenic lesions involving the central (perirolandic cortices), parietal, and occipital lobes. This junctional cortex within the hemisphere (in contrast to anterior and posterior quadrantotomies) presents unique challenges when contemplating a complete disconnection of the region. The surgical technique is achieved through six distinct steps: fronto-central, inferior frontoparietal, lateral temporo-occipital, medial frontal, basal temporo-occipital, and posterior parasagittal callosal disconnections. The functional neuroanatomy of each step is described, along with cadaveric dissections. The authors describe this technique and include a case description of a young girl who presented with childhood-onset intractable epilepsy associated with cognitive stagnation. The postoperative seizure outcome in this patient remains excellent at 2 years' follow-up, with gains in cognition and behavior. Excellent seizure outcomes can be achieved if the network encompassing the entire epileptogenic cortex is disconnected while ensuring preservation of fiber systems that link functionally eloquent uninvolved cortices adjacent to the central quadrant.

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.

Outcome Predictors of Lesional Posterior Cortex Epilepsy Surgery.

BACKGROUND: Lesional posterior cortex epilepsy (PCE) is often drug resistant and may benefit from surgical intervention. In this study, we aimed to identify potential predictive factors associated with seizure recurrence after epilepsy surgery in lesional PCE. METHODS: We retrospectively reviewed patients with PCE who underwent surgery between 1998 and 2021. They were divided into 2 groups according to seizure outcome; the seizure-free group (group 1) and the non-seizure-free group (group 2). The relationship among clinical factors, electroencephalography (EEG) or cranial magnetic resonance imaging findings, disease, and seizure outcome was investigated. RESULTS: A total of 60 patients, with a mean age of 27.26 ± 12.35 years (range, 9-61 years), were included in the study. There were 31 patients (51.66%) in group 1 (Engel class I) and 29 patients (48.33%) in group 2 (13 [21.66%], 10 [16.66%], and 6 [10%] patients in Engel class II, III, and IV, respectively), with a mean follow-up of 8.95 ± 6.96 years (range, 1-24 years). No difference was observed regarding age, gender, age at seizure onset, operation type, treatment gap, and presence of bilateral lesions between the groups (P > 0.05). However, bilateral findings on interictal EEG and gliosis as the underlying disease were predictors of seizure recurrence (P < 0.05). CONCLUSIONS: More than half of the patients (including 2 with bilateral magnetic resonance imaging lesions) were seizure free at long-term follow-up. However, patients with bilateral findings on interictal EEG and gliosis were more likely to have recurrent seizures after surgery. Because lesional PCE is almost always drug resistant and has a potential for favorable outcomes, epilepsy surgery should be considered early.

Insular glioblastoma: surgical challenges, survival outcomes and prognostic factors.

BACKGROUND: Insular gliomas are unique, challenging and evoke a lot of interest amongst neurosurgeons. Publications on insular glioma generally focus on the surgical intricacies and extent of resection pertaining to the low-grade gliomas. Insular glioblastomas (iGBM) have not been analysed separately before. METHODS: Histologically proven WHO grade IV gliomas involving the insula over a 9-year period were studied. Their clinical presentation, radiological features, surgical findings and survival outcomes were assessed. Statistical methods were used to determine the favourable predictors of survival. RESULTS: Out of 27 patients (M:F = 2.9:1), 18 (66%) patients had a tumour extension beyond the insula, 10 (37%) of whom had basal ganglia involvement. Total, near total and subtotal excisions were performed in 7 (26%), 9 (33%) and 11 (40.7%) patients, respectively. Twenty-three patients had glioblastoma, while four had gliosarcoma. IDH mutation was negative in six of the seven patients where it was done. Median overall survival was 5 months. Multivariate analysis showed that a female gender (p = 0.013), seizures in the preoperative period (p = 0.048) and completion of adjuvant therapy (p = 0.003) were associated with a longer survival. CONCLUSION: Insular glioblastomas have a poor prognosis. Insular location and certain tumour characteristics often limit the extent of resection of iGBMs. Moreover, postoperative complications sometimes negate the advantages of a radical resection. A female gender, presentation with seizures and completion of adjuvant chemoradiotherapy appear to be good prognostic factors.

Interhemispheric contralateral approach: the falx as a retractor.

The contralateral transfalcine approach is a valuable option to access lesions around the mesial surface of the brain hemispheres. Despite a favourable perspective, surgical manoeuvres within the interhemispheric fissure carry a risk of inadvertent injury to the healthy cortex on the craniotomy side. To overcome this drawback, a new method of brain retraction was developed. After dissecting the interhemispheric fissure, the falx was incised in an upside-down U-shaped manner and hinged inferiorly, taking care not to violate the inferior sagittal sinus. The falcine flap was reflected laterally and fixed to the lateral edge of the craniotomy, providing homogeneous retraction of the ipsilateral mesial cortex. Surgery proceeded with the brain surface hidden from the surgeon's view and protected by the flap. The absence of retractor devices hindering the surgeon's movements further simplified the procedure.

The microanatomy of the Sylvian fissure.

PURPOSE: Microsurgical anatomy of the Sylvian fissure is still a popular research topic for neurosurgeons. It is important for surgeons who perform skull base and Sylvian fissure surgical procedures to master the anatomy of the region. In our study, we aimed to review the current literature on the subject. METHODS: We reviewed the literature concerning the Sylvian fissure. In addition, we made a microdissection of four human cadaveric brains in order to take images of relevant anatomic structures. RESULTS: The Sylvian fissure includes both superficial and deep compartments. From the beginning of the surface structures and variable thickened subarachnoid membrane to the vascular structures located at the operculo-insular compartment, the surgical technique requires meticulous dissection in all stages of the surgery. CONCLUSIONS: From the view of neurosurgery, novel anatomical knowledge should enhance the success of the surgery. From the view of neuroscience, the Sylvian fissure and the Sylvian cistern have unique anatomical, vascular, and genotypical properties to the other areas of the cerebrum, making them complex and special.

Correlation of Preoperative Functional Magnetic Resonance Imaging (fMRI) with Intraoperative Cortical Stimulation in Surgeries of Eloquent Brain Lesions.

Background: Direct Cortical Stimulation (DCS) represents the gold standard for mapping of eloquent brain cortex. However, DCS is an invasive and time-consuming procedure. fMRI has become a useful tool to delineate motor and sensory eloquent cortex from the areas of planned neurosurgical resection. In our study, we will be studying the reliability of preoperative imaging when compared with the intraoperative DCS. Objectives: The aim of this study was to assess the reliability of fMRI by comparing it with DCS. Methods and Materials: Thirty patients with eloquent cortex lesions were admitted. Preoperative fMRI sequences were loaded into a neuro-navigational system. Intraoperative motor mapping was done by DCS. The location of all cortical stimulated points was correlated with the cortical functional structures. Based on it, specificity, sensitivity, positive predictive value, negative predictive value of fMRI was calculated. Preoperative and postoperative Karnofsky score and MRC grading was then noted. Results: Concordance between fMRI and DCS was noted in 26 cases. Overall mean sensitivity, specificity, positive and negative predictive value of fMRI as compared to DCS was 95%, 92.48%, 85.56%, and 96.08%, respectively. Preoperative and Postoperative Karnofsky score stayed same in most of the cases [25/30]. Conclusions: DCS remains the gold standard for mapping eloquent cortex in-spite of its invasiveness, side effects such as seizures and cost concerns. Although fMRI cannot replace DCS, it can guide and increase the efficacy in resection, select high-risk patients for intraoperative monitoring, help in preoperative stratification of risk counseling and preservation of neurological status in eloquent brain lesions.

Prediction of Postoperative Speech Dysfunctions in Neurosurgery Based on Cortico-Cortical Evoked Potentials and Machine Learning Technology.

Intraoperative recording of cortico-cortical evoked potentials (CCEPs) enables studying effective connections between various functional areas of the cerebral cortex. The fundamental possibility of postoperative speech dysfunction prediction in neurosurgery based on CCEP signal variations could serve as a basis to develop the criteria for the physiological permissibility of intracerebral tumors removal for maximum preservation of the patients' quality of life. The aim of the study was to test the possibility of predicting postoperative speech disorders in patients with glial brain tumors by using the CCEP data recorded intraoperatively before the stage of tumor resection. Materials and Methods: CCEP data were reported for 26 patients. To predict the deterioration of speech functions in the postoperative period, we used four options for presenting CCEP data and several machine learning models: a random forest of decision trees, logistic regression, and support vector machine method with different types of kernels: linear, radial, and polynomial. Twenty variants of models were trained: each in 300 experiments with resampling. A total of 6000 tests were performed in the study. Results: The prediction quality metrics for each model trained in 300 tests with resampling were averaged to eliminate the influence of "successful" and "unsuccessful" data grouping. The best result with F1-score = 0.638 was obtained by the support vector machine with a polynomial kernel. In most tests, a high sensitivity score was observed, and in the best model, it reached a value of 0.993; the specificity of the best model was 0.370. Conclusion: This pilot study demonstrated the possibility of predicting speech dysfunctions based on CCEP data taken before the main stage of glial tumors resection; the data were processed using traditional machine learning methods. The best model with high sensitivity turned out to be insufficiently specific. Further studies will be aimed at assessing the changes in CCEP during the operation and their relationship with the development of postoperative speech deficit.

Small Sphenoid Ridge as a Factor Associated with Laterally Deviated Proximal Sylvian Fissure in Patients Undergoing Pterional Craniotomy.

BACKGROUND: During the pterional-transsylvian approach, we sometimes encounter the proximal Sylvian fissure (SF) deviating laterally beyond the fold of the sphenoidal ridge (SR) and experience difficulty dissecting the SF due to the deep and oblique dissection plane. In the present study, we explored the association between the height of the SR and lateral deviation of the SF during the pterional-transsylvian approach. METHODS: The association between the height of the SR on axial computed tomography and the presence of a laterally deviated SF was evaluated by reviewing patients who had undergone pterional craniotomy. RESULTS: Among the 52 patients included, lateral deviation of the SF was observed in 8 patients (13.4%). The median height of the SR was significantly smaller in patients with laterally deviated SF (6.0 mm) than in patients with non-deviating SF (13.4 mm; P < 0.0001). The oculomotor nerves and middle fossa were observed at the edge of the dissection plane of the SF in all patients with a laterally deviating SF, while medial structures such as the internal carotid artery or optic nerve were observed in patients with non-deviating SF. CONCLUSIONS: Small SR was associated with lateral deviation of the proximal SF.

Resection of Insular Glioma Through the Transfrontal Limiting Sulcus Approach.

BACKGROUND: The current transsylvian or transopercular approaches make access difficult because of the limited exposure of insular tumors. Hence, maximal and safe removal of insular gliomas is challenging. In this article, a new approach to resect insular gliomas is presented. OBJECTIVE: To determine whether the new transfrontal limiting sulcus approach is helpful for maximal and safe removal of insular gliomas. METHODS: The authors reported surgical techniques for insular gliomas resected through the transfrontal limiting sulcus approach. The authors evaluated the surgical resections of 69 insular gliomas performed through the new approach in their department. The extents of resection and postoperative neurological outcomes were analyzed to determine the value of this new approach. RESULTS: Based on the Berger-Sanai classification, most insular gliomas were giant tumors (59.42%), followed by zone I + IV tumors (24.64%). The median (interquartile range) extent of resection of all patients was 100% (91%, 100%). The total resection rate for all gliomas was (55 of 69, 79.7%), and the total resection rate for low-grade gliomas was (28 of 40, 70%), which was significantly lower than that for high-grade gliomas (27 of 29, 93.1%) (P = .019). All patients had muscle strength greater than grade 4 3 months after surgery. Only 1 patient had a speech disorder 3 months after surgery. The median Karnofsky Performance Status score at the time of the 3-month follow-up was 90. CONCLUSION: The transfrontal limiting sulcus approach can help to achieve maximal and safe removal of insular gliomas.

Pearls & Oy-sters: Two Cases of Stereotactic EEG-Proven Insular Epilepsy With Nonlocalizing Scalp EEG and Interesting Semiologies.

Insular epilepsy is a great mimicker and can be mistaken for seizures originating from other areas of the brain or as nonepileptic spells. The semiology of insular epilepsy can include, but is not limited to, auditory illusions, paresthesias, gastric rising, laryngeal constriction, and hyperkinetic movements. These arise from both the functions of the insula itself and its extensive connections with other regions of the brain. Noninvasive workup can be negative or nonlocalizing because of the insula's location deep within the lateral sulcus. Stereotactic EEG can therefore be an important tool in cases of insular epilepsy so that patients may be appropriately diagnosed and evaluated for potential surgical treatment. We present 2 cases of epilepsy with nonlocalizing scalp EEG and challenging semiologies, the workup undertaken to identify them as cases of insular epilepsy, and subsequent surgical treatments and outcomes.