Arteries of the insula

Mathematical and Dynamic Modeling of the Anatomical Localization of the Insula in the Brain

The insula, a deeply situated cortical structure beneath the Sylvian sulcus, plays a critical role in sensory integration, emotion regulation, and cognitive control in the brain. Although several studies have described its anatomical and functional characteristics, mathematical models that quantitatively represent the insula's complex structure and connectivity are lacking. This study aimed to develop a mathematical model to represent the anatomical localization and functional organization of the insula, drawing on current neuroimaging findings and established anatomical data. A three-dimensional (3D) ellipsoid model was constructed to mathematically represent the anatomical boundaries of the insula using Montreal Neurological Institute (MNI) coordinate data. This geometric model adapts the ellipsoid equation to reflect the spatial configuration of the insula and is primarily based on cytoarchitectonic mapping and anatomical literature. Relevant findings from prior imaging research, particularly those reporting microstructural variations across insular subdivisions, were reviewed and conceptually integrated to guide the model's structural assumptions and interpretation of potential applications. The ellipsoid-based 3D model accurately represented the anatomical dimensions and spatial localization of the right insula, centered at the MNI coordinates (40, 5, 5 mm), and matched well with the known volumetric data. Functional regions (face, hand, and foot) were successfully plotted within the model, and statistical analysis confirmed significant differences along the anteroposterior and superoinferior axes (p < 0.01 and p < 0.05, respectively). Dynamic simulations revealed oscillatory patterns of excitatory and inhibitory neural activity, consistent with established insular neurophysiology. Additionally, connectivity modeling demonstrated strong bidirectional interactions between the insula and key regions, such as the prefrontal cortex and anterior cingulate cortex (ACC), reflecting its integrative role in brain networks. This study presents a scientifically validated mathematical model that captures the anatomical structure, functional subdivisions, and dynamic connectivity patterns of the insula. By integrating anatomical data with computational simulations, this model provides a foundation for future research in neuroimaging, functional mapping, and clinical applications involving insula-related disorders.

Motor Outcome After Posterior Insular Resection for Pediatric Epilepsy

The increasingly widespread use of stereo-EEG in the pre-surgical evaluation has led to greater recognition of the insula as both a source and surgical target for drug-resistant epilepsy. Clinicians have long appreciated the challenges of diagnosing and treating seizures arising from the insula. Insular-onset seizures present with a wide variety of semiologies due to its dense and complex integration with other brain structures, resulting in the insula's reputation as the "great mimicker." Surgical access to the insula is guarded by the overlying frontal, temporal, and parietal opercula and requires careful negotiation of the Sylvian fissure, the vascular candelabra of the middle cerebral artery, and protection of crucial white matter structures (e.g., corona radiata). Despite these difficulties, open surgical intervention for insular epilepsy is associated with favorable seizure control rates, surpassing those achieved with less-invasive alternatives (e.g., laser ablation). Technical nuances that minimize the risk of adverse functional outcomes following open insular resection (especially hemiparesis) are of tremendous value to the epilepsy surgeon. Here, we review the literature on hemiparesis secondary to insular resection and detail strategies for achieving safe and thorough resection of the insula, with emphasis placed on the posterior insula. We supplement this review with four illustrative cases in which focal, drug-resistant epilepsy was managed via open insular resection with no resultant permanent hemiparesis. Technical insights accumulated through these cases are highlighted.

Porto Alegre Line predicts lenticulostriate arteries encasement and extent of resection in insular gliomas. A preliminary study

Object

In insular glioma surgery, lenticulostriate arteries (LSTa) tumoral encasement increases neurological deficits risk despite intensive efforts to preserve the internal capsule's integrity. In this study, we focus on the LSTa relationships with the medial aspect of the insular tumors. We propose a new non-invasive method for LSTa involvement prediction in preoperative MRI (Porto Alegre Line). We compare it with direct intraoperative encased LSTa visualization.

Methods

A retrospective review of our database of 52 patients of insular glioma was performed. In cases with no tumor located medial to Porto Alegre line, our medial resection limit, mainly for the tumor part located next to the limen insula, was the inferior fronto-occipital fasciculus (IFOF), identified through altered speech patterns during electric subcortical stimulation. In cases with no assumed LSTa involvement, the parameter used to stop resection was the confirmation of the corticospinal tract with 10-mA stimulus. The resection limit of tumors placed medially to the Porto Alegre line was intraoperative direct LSTa visualization.

Results

The LSTa involvement was the most critical medial limiting factor in more aggressive tumor resection and an excellent overall survival (P = 0.022). In cases in which there were direct intraoperative LSTa encasement visualization, Porto Alegre Line was employed as an MRI preoperative landmark for prediction of LSTa involvement in those patients with Sensitivity, Specificity, Positive Predictive Values of 1, 0.975 and 0.923, respectively.

Conclusion

We have found that LSTa encasement is a limiting factor to reach a satisfactory extent of resection and that Porto Alegre Line can predict it.

The Role of the Claustrum in Parkinson's Disease and Vascular Parkinsonism: A Matter of Network?

BACKGROUND

The mechanisms underlying extrapyramidal disorders and their anatomical substrate have been extensively investigated. Recently, the role of the claustrum in Parkinson's disease and other neurodegenerative conditions has been better detailed. The main aim of this review was to summarize the supporting evidence for the role of the claustrum in degenerative and vascular parkinsonism.

METHODS

The anatomy, biology, vascular supply, and connections of the claustrum in humans were identified and described, providing the substrate for the vascular involvement of the claustrum in large- and small-vessel disease. The vascular supply of the claustrum includes up to three different sources from a single artery, the middle cerebral artery, and it is known as territory with an intermediate hemodynamic risk. The connections of the claustrum make it a sensory integrator and a relevant point in several networks, from consciousness to movement planning.

CONCLUSIONS

The claustrum is still an incompletely explained structure. However, recent description of its multiple connections indicate that it is involved in several diseases, including Parkinson's disease. The evidence underlying its potential role in vascular parkinsonism is still scarce, but it might be a field warranting future investigations.

Laser interstitial thermal therapy in the management of bottom-of-sulcus dysplasia-related epilepsy

OBJECTIVE

This study assessed the efficacy and safety of magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) versus open surgery (OS) for the treatment of patients with bottom-of-sulcus dysplasia (BOSD)-related epilepsy.

METHODS

Twenty-two patients underwent MRgLITT, while 39 underwent OS. Postoperative seizure-free rates were analyzed using Kaplan-Meier curves. The removal ratio, which represents the extent of damage, was calculated based on preoperative lesion volume and postoperative removal volume. Other outcomes, including adverse events, operative time, and hospital stay, were also compared.

RESULTS

Kaplan-Meier curves indicated the seizure-free rates were comparable between the MRgLITT group (90.9%, 26.5 [23.0, 35.1] months) and OS group (89.7%, 25.2 [16.2, 34.6] months) at the final follow-up (p = 0.901, log-rank test). The removal ratio of MRgLITT (1.3 [1.1, 1.7]) was significantly lower (p = 0.007) than that of OS (5.8 [3.6, 8.5]). A comparison of postoperative neurological deficits, infection rates, and fever rates revealed no significant differences between MRgLITT and OS groups. The operative time (hours) of MRgLITT (3.0, [2.1, 4.9]) was significantly shorter (p = 0.007) than that of OS (3.5 [3.0, 4.5]). The hospital stay (days) after MRgLITT (6 [5.0, 7.5]) was significantly shorter (p < 0.001) than that of OS (11.0 [9.0, 13.5]).

INTERPRETATION

MRgLITT has advantages over OS, including comparable seizure control and adverse event profiles, along with reduced removal ratios, shorter operative time, and shorter hospital stays.

Mini-strokes within Broca-caudate connections during left insular glioma awake surgery cause transient severe naming deficits

OBJECTIVE

To provide an explanation for the intraoperative onset of severe naming deficits in the course of awake resection of left insular glioma.

METHODS

We retrospectively reviewed a series of 14 patients operated on in awake conditions for a left insular IDH-mutated glioma. Preoperative MRI included high-resolution diffusion sequences, to which constrained spherical deconvolution pipeline was applied, to obtain a whole brain tractogram. Whole brain T1 parcellation was obtained by Freesurfer, allowing to dissect the tractogram and identify the connections between the caudate nucleus and Broca's area. Postoperative MRI standard diffusion the day after surgery was performed, allowing to delineate and register to the preoperative MRI any area of hyperintense diffusion with low apparent diffusion coefficient. The pathway between pars triangularis (resp. opercularis) and Broca's area were considered as damaged whenever more than 50% of streamlines were passing through the mini-strokes. Patients' language abilities (including a picture naming task) were assessed and reported before, during and after surgery by certified speech therapists. Severe postoperative naming deficits were defined as a score lower than 40/80 items. Contingency tables were analyzed with Fisher exact test (statistical significance set at 0.05).

RESULTS

Out the 14 patients, 8 patients had a mini-stroke on the immediate postoperative MRI. None of the 6 patients without any stroke had postoperative naming severe deficits. Five out the 8 patients with a mini-stroke had a severe postoperative naming deficit, characterized by strong verbal perseverations. This difference was statistically significant (exact Fisher test, p = 0.03). For the five patients with a deficit, the mini-stroke damaged either the pars triangularis - caudate pathway or the pars opercularis - caudate pathway, whenever the pars triangularis was resected after negative cortical mapping. For the three patients without severe postoperative naming deficit, the mini-stroke spared the Broca-caudate pathway. All patients recovered quasi-normal naming abilities at the 4-month postoperative evaluation.

CONCLUSIONS

The occurrence of mini-strokes within the connections between Broca's area and the caudate nucleus explains the sudden naming deficits observed intraoperatively in some patients during awake resection of IDH-mutated insular glioma. Further studies are needed to better predict such event and to assess its impact on other cognitive functions.

Prevalence and Distribution of Intracranial Vessel Occlusion on Angiography and Its Association with Functional Outcome in Patients with Atrial Fibrillation Presenting with Ischemic Stroke

OBJECTIVES

To determine the prevalence and distribution of intracranial vessel occlusion identified on computed tomography (CT) or magnet resonance (MR) angiography and to explore its association with functional outcome in patients with atrial fibrillation (AF) and ischemic stroke.

METHODS

Multicenter cohort study enrolling consecutive patients with AF with imaging-confirmed ischemic stroke who underwent CT- or MR-angiography on admission (2014-2022). Multivariable regression was used to explore the association between intracranial vessel occlusion and poor functional outcome (modified Rankin Scale score 3-6) at 90 days.

RESULTS

The analysis included 10,164 patients (median age 81.5 years, 47.8% female, median National Institutes of Health Stroke Scale score on admission 6; 14.7% on a vitamin K antagonist [VKA], 27.5% on a direct oral anticoagulant [DOAC], 57.8% not receiving oral anticoagulation). Angiography showed intracranial vessel occlusion in 5,190 patients (51.1%), affecting the anterior cerebral circulation in 87.4%. Overall, 29.2% and 29.4% of patients received thrombolysis and mechanical thrombectomy, respectively. The proportion of patients with poor functional outcome at 90 days was 60.6% and 42.7% in those with and without vessel occlusion, respectively. In multivariable analyses, vessel occlusion was associated with poor functional outcome (adjusted odds ratio [aOR]: 1.95, 95% confidence interval [CI]: 1.71-2.22) with consistent results in subgroups according to oral anticoagulation use (VKA, aOR: 1.98, 95% CI: 1.40-2.80; DOAC, aOR: 2.35, 95% CI: 1.83-3.03; none, aOR: 1.76, 95% CI: 1.49-2.09).

INTERPRETATION

Intracranial vessel occlusion is common in patients with AF with ischemic stroke, mainly affects the anterior circulation and is associated with poor functional outcome. ANN NEUROL 2024;96:1115-1123.

Insular Epilepsy: Functions, Diagnostic Approaches, and Surgical Interventions

Epilepsy, a chronic neurological disorder characterized by recurrent seizures, affects a significant portion of the global population, with drug-resistant epilepsy (DRE) presenting a major treatment challenge. Insular epilepsy, originating from this complex region, exhibits a broad range of symptoms, making diagnosis particularly difficult. Advanced imaging techniques and invasive procedures like stereoelectroencephalography (SEEG) are often crucial for accurately localizing the epileptogenic zone. Surgical resection remains the primary treatment for DRE, with recent advancements in microsurgical techniques and neuroimaging improving outcomes. Additionally, minimally invasive approaches like laser interstitial thermal therapy (LITT) and radiofrequency thermocoagulation (RFTC) offer promising alternatives.

Development of a predictive grading system for postoperative ischemia following middle cerebral artery aneurysm clipping

The current study presents a single-surgeon experience with microsurgical clipping of middle cerebral artery (MCA) aneurysms and introduces a grading system to predict postoperative ischaemia. A retrospective analysis of 222 patients with 251 MCA aneurysms treated between 2015 and 2024 was conducted. Key factors, including aneurysm size, dome morphology, neck location, calcification, and rupture status, were evaluated to identify predictors of radiological infarction. A scoring model was developed, assigning points for aneurysm neck distance from the internal carotid artery (>20 mm: 1 point; 10-20 mm: 2 points; <10 mm: 3 points), aneurysm size > 7 mm (1 point), calcification (1 point), and rupture status (1 point). The grading system demonstrated a significant risk gradient, with infarction rates of 0 %, 3 %, 11 %, 35 %, and 83 % for grades 1 to 5, respectively (p < 0.0001). Independent predictors of poor outcomes were identified as a short M1 segment (p = 0.002), aneurysm size > 7 mm (p = 0.019), calcification (p < 0.001), and rupture presentation (p = 0.002). Postoperative ischaemia occurred in 7 patients (23 %) with ruptured aneurysms and 18 patients (9 %) with unruptured aneurysms. This grading system provides a practical tool for stratifying risk and guiding treatment decisions. Further multi-centre studies are needed to validate its broader applicability.

Surgical Anatomy and Technique of Peri-Insular Hemispherotomy in Pediatric Epilepsy

BACKGROUND AND OBJECTIVES

Hemispherotomy is a highly complex procedure that demands a steep learning curve. An incomplete brain disconnection often results in failure of seizure control. The purpose of this article was to present a step-by-step guide to the surgical anatomy of this procedure. It is composed of a 7-stage approach, enhancing access to and improving visualization of deep structures.

METHODS

A retrospective analysis of 39 pediatric patients with refractory epilepsy who underwent this technique was conducted. Engel scores were assessed 1 year postsurgery. Cadaveric dissections were performed to illustrate the procedure.

RESULTS

Between 2015 and 2022, 39 patients were surgically treated using the peri-insular technique. The technique involved 7 stages: patient positioning, operative approach, opercular resection, transventricular callosotomy, fronto-orbital disconnection, anterior temporal disconnection, and posterior temporal disconnection. Most of the patients (92.30%) were seizure-free (Engel class I) at 1 year postoperative, 5.13% were nearly seizure-free (Engel II), and 2.56% showed significant improvement (Engel III). Complications occurred in 8% of cases, including 1 infection, 2 cases of aseptic meningitis, and 1 non-shunt-requiring acute hydrocephalus.

CONCLUSION

The peri-insular hemispherotomy technique offers excellent seizure control with a low complication rate. Our visual documentation of surgical anatomy, complemented by detailed descriptions of surgical nuances, significantly contributes to a comprehensive understanding of this technique.

Correlation Between Cognitive Impairment and Lenticulostriate Arteries: A Clinical and Radiomics Analysis

Lenticulostriate arteries (LSA) are potentially valuable for studying vascular cognitive impairment. This study aims to investigate correlations between cognitive impairment and LSA through clinical and radiomics features analysis. We retrospectively included 102 patients (mean age 62.5±10.3 years, 60 males), including 58 with mild cognitive impairment (MCI) and 44 with moderate or severe cognitive impairment (MSCI). The MRI images of these patients were subjected to z-score preprocessing, manual regions of interest (ROI) outlining, feature extraction (pyradiomics), feature selection [max-relevance and min-redundancy (mRMR), least absolute shrinkage and selection operator (LASSO), and univariate analysis], model construction (multivariate logistic regression), and evaluation [receiver operating characteristic curve (ROC), decision curve analysis (DCA), and calibration curves (CC)]. In the training dataset (71 patients, 44 MCI) and the test dataset (31 patients, 17 MCI), the area under curve (AUC) of the combined model (training 0.88 [95% CI 0.78, 0.97], test 0.76 [95% CI 0.6, 0.93]) was better than that of the clinical model and the radiomics model. The DCA results demonstrated the highest net yield of the combined model relative to the clinical and radiomics models. In addition, we found that LSA total vessel count (0.79 [95% CI 0.08, 1.59], P = 0.038) and wavelet.HLH_glcm_MCC (-1.2 [95% CI -2.2, -0.4], P = 0.008) were independent predictors of MCI. The model that combines clinical and radiomics features of LSA can predict MCI. Besides, LSA vascular parameters may serve as imaging biomarkers of cognitive impairment.

Impact of preaneurysmal M1 length in unruptured middle cerebral artery aneurysm: mid-term outcome and single-center experience

OBJECTIVE

This study was design to investigate the surgical and functional outcome based on the preaneurysmal M1 length for unruptured MCA aneurysm.

METHODS

Among 250 consecutive patients with unruptured aneurysms operated in our institution between 2015 and 2017, 72 were MCA aneurysms. Risk factors for IR (i.e., intraoperative rupture) were investigated including age, sex, preaneurysmal M1 length, maximal MCA aneurysm diameter, neck size, aneurysm shape, sphenoid ridge proximation sign. Outcome was measured at discharge, 1 yr and last follow-up. Outcome was compared according to the preaneurysmal M1 length.

RESULTS

Among 68 patients included, five patients (7.3%) suffered IR. Mean maximal diameter of MCA aneurysm (7.9 mm ± 3.4 vs. 4.5 ± 1.8; p = 0.01) was significantly associated with IR risk. Mean M1 length seemed to be shorter in the IR group although not statistically significant (16.2 mm ± 5.1 vs. 11.5 mm ± 4.8; p = 0.053). Mid-term outcome was favorable for all patients at last follow-up but was worsen in case of short preaneurysmal M1 segment (10.7 mm ± 4.8 vs. 16.4 mm ± 5.3, p = 0.02). Complete aneurysm occlusion was achieved for sixty-nine patients (95.5%) with 6.9% of early postoperative complications.

CONCLUSIONS

The microsurgical treatment of unruptured MCA aneurysm was associated with favorable mid-term outcome in all patients and high rates of complete occlusion. Aneurysm size was significantly associated with the intraoperative rupture risk for unruptured MCA aneurysm and patients with a short preaneurysmal M1 segment seemed to have a greater risk of intraoperative rupture although not statistically significant. Short preaneurysmal M1 patients had worsen mid-term outcome.

Isolated insular stroke: topography is the answer with respect to outcome and cardiac involvement

Background and purpose

Isolated insular strokes (IIS) are a rare occurrence due to the frequent concomitant involvement of adjacent territories, supplied by the M2 segment of the middle cerebral artery (MCA), and clinical aspects are sometimes contradictory. We aimed to describe clinical and radiological characteristics of a pure IIS case series, focusing on its functional outcome and cardiac involvement.

Methods

We identified 15 isolated insular ischemic strokes from a pool of 563 ischemic strokes occurred between January 2020 and December 2021. Data collection consisted of demographic and baseline clinical characteristics, comorbidities, electrocardiograms, echocardiograms, stroke topography and etiology, reperfusive treatments, and outcome measures. Descriptive statistical analysis was carried out.

Results

Newly detected cardiovascular alterations were the prevalent atypical presentation. Cardioembolism was the most frequent etiology. Most of patients had major neurological improvement at discharge and good outcome at 3-months follow-up.

Discussion and conclusion

IIS are extremely rare, representing according to our study about 2.6% ischemic strokes cases per year, and patients have peculiar clinical manifestations, such as dysautonomia and awareness deficits. Our data suggest the possibility for these patients to completely recover after acute ischemic stroke notwithstanding the pivotal role of the insula in cerebral connections and the frequent association with MCA occlusion. Moreover, given the central role of the insula in regulating autonomic functions, newly detected cardiac arrhythmias must be taken into consideration, as well as a full diagnostic work-up for the research of cardioembolic sources. To our knowledge, this is the largest monocentric case series of IIS and it might be useful for future systematic reviews.

Neurological morbidity of surgery for suprasylvian operculoinsular epilepsy

OBJECTIVE

The objective of this study was to identify risk factors associated with surgery-related neurological morbidity in patients with drug-resistant epilepsy undergoing suprasylvian operculoinsular resections. As secondary outcomes, we also analyzed the risk factors for ischemic lesion (IL) of corona radiata and seizure recurrence.

METHODS

A retrospective analysis was conducted on a cohort of patients who underwent suprasylvian operculoinsular resections for drug-resistant epilepsy. The association of several presurgical, surgical, and postsurgical factors with both primary (persistent neurological deficits) and secondary (structural abnormalities on postoperative magnetic resonance imaging [MRI] and seizure recurrence) postoperative outcomes was investigated with univariate and multivariate statistical analysis.

RESULTS

The study included a total of 65 patients; 46.2% of patients exhibited postoperative neurological deficits, but only 12.3% experienced persistent deficits. On postoperative MRI, IL in the corona radiata and corticospinal tract Wallerian degeneration (CSTWd) were seen in 68% and 29% of cases, respectively. Only CSTWd was significantly associated with persistent neurological deficits (relative risk [RR] = 2.6). Combined operculoinsular resection (RR = 3.62) and surgery performed on the left hemisphere (RR = .37) were independently associated with IL in the corona radiata. Variables independently associated with CSTWd were the presence of malacic components in the IL (RR = 1.96), right central operculum resection (RR = 1.79), and increasing age at surgery (RR = 1.03). Sixty-two patients had a postoperative follow-up > 12 months (median = 56, interquartile range = 30.75-73.5), and 62.9% were in Engel class I at last outpatient control. The risk of seizure recurrence was reduced by selective opercular resection (RR = .25) and increased by the histological diagnosis of aspecific gliosis (RR = 1.39).

SIGNIFICANCE

This study provides insights into the risk factors associated with surgery-related neurological morbidity, as well as further evidence on the postoperative occurrence of subcortical injury and seizure recurrence in epileptic patients undergoing suprasylvian operculoinsular resections. The findings highlighted in this study may be useful to better understand the processes supporting the increased surgical risk in the operculoinsular region.

Targeted Physiotherapy for an Interesting Case of Spontaneously Resolving Extracapsular Infarct: A Case Report

Stroke is a prevalent and disabling illness that is becoming more common in developing countries. After a stroke, physical inactivity frequently results in long-term deconditioning and disappointing consequences. This case study focuses on an infrequent 0.3% of ischemic stroke cases that occur in the external capsular (ECC) or extreme capsular (EXC) region. In sub-insular infarcts, ECC-EXC lesions are distinct and frequently linked to the anterior opercular syndrome. We are presenting the case of an 86-year-old female patient who had a fall and loss of consciousness. Diagnostic tests revealed that the patient had an extracapsular ischemic event; due to unstable vital signs and frequent drop in saturation of peripheral oxygen (SpO2) levels, the patient was intubated and admitted to the intensive care unit (ICU). When stable, the patient experienced generalized weakness, for which she was referred for physical therapy. Balance and gait impairments were secondary to weakness. A planned two-week structured physiotherapy intervention was created with an emphasis on gait training, muscle strengthening, and balance. Adaptive gait training, progressive exercises, and balancing activities addressed the patient's limitations. This case study demonstrates how an elderly individual with an external capsule ischemic event can benefit from targeted physical therapy for increasing muscle strength, balance, and gait performance. Positive results emphasize how crucial early and targeted physiotherapy is for supporting stroke survivors' neurological recovery.

Neurophysiologic cut off values for safe resection of patients with supratentorial gliomas

BACKGROUND

Gliomas have infiltrative nature and tumor volume has direct prognostic value. Optimal resection limits delineated by high-frequency monopolar stimulation with multipulse short train technique is still a matter of debate for safe surgery without (or with acceptable) neurological deficits. It is also an enigma whether the same cut-off values are valid for high and low grades. We aimed to analyze the value of motor mapping/monitoring findings on postoperative motor outcome in diffuse glioma surgery.

METHODS

Patients who were operated on due to glioma with intraoperative neuromonitorization at our institution between 2017 and 2021 were analyzed. Demographic information, pre- and post-operative neurological deficit, magnetic resonance images, resection rates, and motor evoked potential (MEP) findings were analyzed.

RESULTS

Eighty-seven patients of whom 55 had high-grade tumors were included in the study. Total/near-total resection was achieved in 85%. Subcortical motor threshold (ScMTh) from resection cavity to the corticospinal tract was ≤ 2mA in 17; 3 mA in 14; 4 mA in 6; 5 mA in 7, and ≥5mA in 50 patients. On the 6th month examination, six patients (5 with high-grade tumor) had motor deficits. These patients had changes in MEP that exceeded critical threshold during monitoring. Receiver operating characteristic analysis revealed 2.5 mA ScMTh as the cut-off point for limb paresis after awakening and 6 months for the groups.

CONCLUSIONS

Subcortical mapping with MEP monitoring helps to achieve safe wider resection. The optimal safe limit for SCMTh was determined as 2.5 mA. Provided that safe threshold values are maintained in MEP, surgeon may force the functional limits by lowering the SCMTh to 1 mA, especially in low-grade gliomas.

Arteries Around the Superior Limiting Sulcus: Motor Complication Avoidance in Insular and Insulo-Opercular Surgery

BACKGROUND AND OBJECTIVES

Insulo-opercular surgery can cause ischemic motor complications. A source of this is the arteries around the superior limiting sulcus (SLS), which reach the corona radiata, but the detailed anatomy remains unclear. To characterize arteries around the SLS including the long insular arteries (LIAs) and long medullary arteries, we classified them and examined their distribution in relation to the SLS, which helps reduce the risk of ischemia.

METHODS

Twenty adult cadaveric hemispheres were studied. Coronal brain slices were created perpendicular to the SLS representing insular gyri (anterior short, middle short, posterior short, anterior long, and posterior long). The arteries within 10-mm proximity of the SLS that reached the corona radiata were excavated and classified by the entry point.

RESULTS

A total of 122 arteries were identified. Sixty-three (52%), 20 (16%), and 39 (32%) arteries penetrated the insula (LIAs), peak of the SLS, and operculum (long medullary arteries), respectively. 100 and six (87%) arteries penetrated within 5 mm of the peak of the SLS. The arteries were distributed in the anterior short gyrus (19%), middle short gyrus (17%), posterior short gyrus (20%), anterior long gyrus (19%), and posterior long gyrus (25%). Seven arteries (5.7%) had anastomoses after they penetrated the parenchyma.

CONCLUSION

Approximately 90% of the arteries that entered the parenchyma and reached the corona radiata were within a 5-mm radius of the SLS in both the insula and operculum side. This suggests that using the SLS as a landmark during insulo-opercular surgery can decrease the chance of ischemia.

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.

Disrupted Brain Functional Status in Patients with Reversible Cerebral Vasoconstriction Syndrome

OBJECTIVES

The aim of this study was to investigate the functional networks in subjects with reversible cerebral vasoconstriction syndrome (RCVS) using resting-state functional magnetic resonance imaging (rs-fMRI).

METHODS

We prospectively recruited patients with RCVS and healthy controls (HCs) between February 2017 and April 2021. The rs-fMRI data were analyzed using graph theory methods. We compared node-based global and regional topological metrics (Bundle 1) and network-based intranetwork and internetwork connectivity (Bundle 2) between RCVS patients and HCs. We also explored the associations of clinical and vascular (ie, the Lindegaard index, LI) parameters with significant rs-fMRI metrics.

RESULTS

A total of 104 RCVS patients and 93 HCs were included in the final analysis. We identified significantly decreased local efficiency of the left dorsal anterior insula (dAI; p = 0.0005) in RCVS patients within 30 days after disease onset as compared to HCs, which improved 1 month later. RCVS patients also had increased global efficiency (p = 0.009) and decreased average degree centrality (p = 0.045), clustering coefficient (p = 0.033), and assortativity values (p = 0.003) in node-based analysis. In addition, patients with RCVS had increased internetwork connectivity of the default mode network (DMN) with the salience (p = 0.027) and dorsal attention (p = 0.016) networks. Significant correlations between LI and regional local efficiency in left dAI (rs  = -0.418, p = 0.042) was demonstrated.

INTERPRETATION

The significantly lower local efficiency of the left dAI, suggestive of impaired central autonomic modulation, was negatively correlated with vasoconstriction severity, which is highly plausible for the pathogenesis of RCVS. ANN NEUROL 2023;94:772-784.

Long insular artery damage might be a key sign for predicting functional prognosis of putaminal hemorrhage

OBJECTIVE

Although the putamen is the most common area of spontaneous intracerebral hemorrhage, previous reports about the effects of surgery are limited. We sometimes experience a poor prognosis in patients in whom there is no damage to the internal capsule, but with injury in the long insular artery (LIA) region. The purpose of this study was to confirm the relationship between LIA damage and patient prognosis following surgery for putaminal hemorrhage.

METHODS

We retrospectively collected data of 287 surgical cases who presented with putaminal hemorrhage between January 2004 and March 2022. Among them, we chose patients without initial damage to the posterior limb of the internal capsule, and divided these patients into two groups, those without (Group A) and with (Group B) final damage in the LIA region. We compared positivity rates of final manual muscle test (MMT) scores≥3 and related factors.

RESULTS

Sixty-three of the 287 patients were included in this study. Of them, 11 cases in Group A were positive for MMT scores≥3 (68.8%) and 9 cases (19.1%) in Group B had MMT scores≥3 seven days after surgery. Group A thus had a significantly higher rate of MMT scores≥3 than group B (p=0.00).

CONCLUSION

In patients without initial damage to the internal capsule, LIA injury might be a key sign for predicting the functional prognosis of putaminal hemorrhage.

Distal stenting technique for coil embolization of early branch aneurysms of middle cerebral artery

BACKGROUND AND PURPOSE

Stent-assisted coil embolization of early branch aneurysms of the middle cerebral artery (MCA) can sometimes be challenging due to the small diameter and acute angle of the branches. This study aimed to analyze the treatment results and report the feasibility and outcomes of the distal stenting technique for these aneurysms.

MATERIALS AND METHODS

The distal stenting technique was used for 15 wide-neck MCA aneurysms (females, 10; males, 5; mean age, 65.1 years) originating from the early branch between December 2018 and October 2021. The average sizes of the dome, depth, and neck of the aneurysms were 4.17 mm (range: 2.99-6.21 mm), 2.86 mm (range: 1.82-3.72 mm), and 3.42 mm (range: 2.44-4.32 mm), respectively.

RESULTS

The average diameter of the stents was 4.0 mm (3.0 mm, 3; 4.0 mm, 6; 4.5 mm, 6). Stents were successfully deployed in all 15 aneurysms (100%). The average length of the procedure was 69 min (range: 45-117 min). On postoperative angiography, nine (60.0%) aneurysms were completely occluded, four (26.7%) had neck remnants, and two (13.3%) had contrast flow in the sac. During the procedure, vasospasm and thrombus formation occurred in one case each, but no neurological sequelae were observed. On follow-up digital subtraction angiography of the 10 aneurysms after an average of 13.7 months (range: 12-18 months), the branches were well preserved, and neck remnants were noted in four aneurysms (40.0%). No thromboembolic events occurred during the clinical follow-up.

CONCLUSION

The distal stenting technique using an open-cell stent can be a good option for coil embolization of early branch MCA aneurysms.

Comparative anatomy of the middle cerebral artery, rhinal and endorhinal sulci, piriform lobe, entorhinal cortex, olfactory tubercule, anterior perforate substance, and hippocampus: A dissection study

The literature describing the complex anatomy of the middle cerebral artery (MCA), lenticulostriate arteries, and recurrent artery of Heubner, does not discuss the comparative anatomy of the cerebrum, MCA, the recurrent artery of Heubner, and the relationship of the MCA with the rhinal sulci. The entorhinal literature does not detail the comparative anatomic modification of the rhinal and endorhinal sulci, piriform lobe and the hippocampus's compressed positional change in the temporal lobe. This investigation's objectives were to analyze the comparative anatomic modifications of the cerebrum, the MCA, lenticulostriate arteries, recurrent artery of Heubner, olfactory tubercule, anterior perforate substance, rhinal sulcus, endorhinal sulcus, piriform lobe, entorhinal cortex, and hippocampus. Brain dissections of adult iguana, rabbit, sheep, cat, dog, macaque, human and human fetal specimens were analyzed. The MCA branches enter the striate nuclei via the endorhinal sulcus, with few branches present in the rhinal sulcus. Modifications of the cerebrum, with the development of gyri and sulci and opercula covering the insula, changes the linear surface configuration of the MCA into a tridimensional one. Similar changes are present in human fetal specimens. The cerebral neocortical expansion changes the position of the rhinal and endorhinal sulci, their relationship with the MCA, the size of the olfactory tubercule, the position and size of the piriform lobe, and the diagonal course of the lenticulostriates and recurrent artery of Heubner. The hippocampus becomes compressed in the inferomedial region of the human temporal lobe. The lenticulostriate arteries are likely the first developed component of the MCA.

Percent Insular Ribbon Infarction for Predicting Infarct Growth Rate and 90-Day Outcomes in Large-Vessel Occlusive Stroke: Secondary Analysis of Prospective Clinical Trial Data

BACKGROUND. Insight into the natural history of infarct growth could help identify patients with slowly progressing stroke who may benefit from delayed endovascular thrombectomy (EVT). OBJECTIVE. The purpose of this article is to evaluate associations of percent insular ribbon infarction (PIRI) with infarct growth rate (IGR) and 90-day outcomes in patients with large-vessel occlusive stroke. METHODS. This retrospective study was a secondary analysis of a prior clinical trial that enrolled patients with acute stroke not treated with reperfusion therapies from January 2007 to June 2009. The present analysis evaluated 31 trial patients (median age, 71 years; 12 women, 19 men) with anterior-circulation large-vessel occlusion who underwent serial MRI examinations. Two neuroradiologists independently scored PIRI on presentation MRI examinations on the basis of the ratio of the length of the portion of the insula showing restricted diffusion to the insula's total length using a previously described 0-4 scale; scores were categorized (mild [0-1], moderate [2], or severe [3-4]), and discrepancies were resolved by consensus. The 90-day modified Rankin Scale (mRS) was obtained. As part of earlier clinical trial analyses, collateral pattern on CTA was classified as symmetric, malignant, or other, and infarct volumes were measured on DWI during the initial 48 hours after presentation and on FLAIR at 90 days. RESULTS. Interrater agreement for PIRI category was strong (κ = 0.89). PIRI was mild in 10, moderate in four, and severe in 17 patients. For mild, moderate, and severe PIRI, median IGR from onset to presentation was 1.6 cm3/h, 8.5 cm3/h, and 17.5 cm3/h (p < .001); median IGR from presentation to 48 hours was 0.3 cm3/h, 0.2 cm3/h, and 1.2 cm3/h (p = .005); median 90-day infarct volume was 9.4 cm3, 39.8 cm3, and 108.6 cm3 (p = .01); and 90-day mRS of 2 or less occurred in 78%, 67%, and 6% of patients (p = .001). In multivariable models controlling for age, internal carotid artery occlusion, and collateral pattern, PIRI category independently predicted onset-to-presentation IGR (β = 1.5), presentation-to-48-hour IGR (β = 1.3), and 90-day mRS of 2 or less (OR = 0.2). For predicting 90-day mRS of 2 or less, mild-to-moderate PIRI had sensitivity of 90.0% and specificity of 84.2%; symmetric collateral pattern had sensitivity of 70.0% and specificity of 73.7%. CONCLUSION. PIRI was independently associated with IGR and 90-day outcome. CLINICAL IMPACT. PIRI may help identify patients who could benefit from late-window EVT when requiring transfer to EVT-capable centers.

Interspecies and regional variability of alcohol action on large cerebral arteries: regulation by KCNMB1 proteins

Alcohol intake leading to blood ethanol concentrations (BEC) ≥ legal intoxication modifies brain blood flow with increases in some regions and decreases in others. Brain regions receive blood from the Willis' circle branches: anterior, middle (MCA) and posterior cerebral (PCA), and basilar (BA) arteries. Rats and mice have been used to identify the targets mediating ethanol-induced effects on cerebral arteries, with conclusions being freely interchanged, albeit data were obtained in different species/arterial branches. We tested whether ethanol action on cerebral arteries differed between male rat and mouse and/or across different brain regions and identified the targets of alcohol action. In both species and all Willis' circle branches, ethanol evoked reversible and concentration-dependent constriction (EC50s ≈ 37-86 mM; below lethal BEC in alcohol-naïve humans). Although showing similar constriction to depolarization, both species displayed differential responses to ethanol: in mice, MCA constriction was highly sensitive to the presence/absence of the endothelium, whereas in rat PCA was significantly more sensitive to ethanol than its mouse counterpart. In the rat, but not the mouse, BA was more ethanol sensitive than other branches. Both interspecies and regional variability were ameliorated by endothelium. Selective large conductance (BK) channel block in de-endothelialized vessels demonstrated that these channels were the effectors of alcohol-induced cerebral artery constriction across regions and species. Variabilities in alcohol actions did not fully matched KCNMB1 expression across vessels. However, immunofluorescence data from KCNMB1-/- mouse arteries electroporated with KCNMB1-coding cDNA demonstrate that KCNMB1 proteins, which regulate smooth muscle (SM) BK channel function and vasodilation, regulate interspecies and regional variability of brain artery responses to alcohol.

The connection between heart rate variability (HRV), neurological health, and cognition: A literature review

The heart and brain have bi-directional influences on each other, including autonomic regulation and hemodynamic connections. Heart rate variability (HRV) measures variation in beat-to-beat intervals. New findings about disorganized sinus rhythm (erratic rhythm, quantified as heart rate fragmentation, HRF) are discussed and suggest overestimation of autonomic activities in HRV changes, especially during aging or cardiovascular events. When excluding HRF, HRV is regulated via the central autonomic network (CAN). HRV acts as a proxy of autonomic activity and is associated with executive functions, decision-making, and emotional regulation in our health and wellbeing. Abnormal changes of HRV (e.g., decreased vagal functioning) are observed in various neurological conditions including mild cognitive impairments, dementia, mild traumatic brain injury, migraine, COVID-19, stroke, epilepsy, and psychological conditions (e.g., anxiety, stress, and schizophrenia). Efforts are needed to improve the dynamic and intriguing heart-brain interactions.

Predictors of outcomes after surgery for medically intractable insular epilepsy: A systematic review and individual participant data meta-analysis

Insular epilepsy (IE) is an increasingly recognized cause of drug-resistant epilepsy amenable to surgery. However, concerns of suboptimal seizure control and permanent neurological morbidity hamper widespread adoption of surgery for IE. We performed a systematic review and individual participant data meta-analysis to determine the efficacy and safety profile of surgery for IE and identify predictors of outcomes. Of 2483 unique citations, 24 retrospective studies reporting on 312 participants were eligible for inclusion. The median follow-up duration was 2.58 years (range, 0-17 years), and 206 (66.7%) patients were seizure-free at last follow-up. Younger age at surgery (≤18 years; HR = 1.70, 95% CI = 1.09-2.66, P = .022) and invasive EEG monitoring (HR = 1.97, 95% CI = 1.04-3.74, P = .039) were significantly associated with shorter time to seizure recurrence. Performing MR-guided laser ablation or radiofrequency ablation instead of open resection (OR = 2.05, 95% CI = 1.08-3.89, P = .028) was independently associated with suboptimal or poor seizure outcome (Engel II-IV) at last follow-up. Postoperative neurological complications occurred in 42.5% of patients, most commonly motor deficits (29.9%). Permanent neurological complications occurred in 7.8% of surgeries, including 5% and 1.4% rate of permanent motor deficits and dysphasia, respectively. Resection of the frontal operculum was independently associated with greater odds of motor deficits (OR = 2.75, 95% CI = 1.46-5.15, P = .002). Dominant-hemisphere resections were independently associated with dysphasia (OR = 13.09, 95% CI = 2.22-77.14, P = .005) albeit none of the observed language deficits were permanent. Surgery for IE is associated with a good efficacy/safety profile. Most patients experience seizure freedom, and neurological deficits are predominantly transient. Pediatric patients and those requiring invasive monitoring or undergoing stereotactic ablation procedures experience lower rates of seizure freedom. Transgression of the frontal operculum should be avoided if it is not deemed part of the epileptogenic zone. Well-selected candidates undergoing dominant-hemisphere resection are more likely to exhibit transient language deficits; however, the risk of permanent deficit is very low.

Arterial Supply of the Basal Ganglia: A Fiber Dissection Study

BACKGROUND

The basal ganglia, a group of subcortical nuclei located deep in the insular cortex, are responsible for many functions such as motor learning, emotion, and behavior control. Nowadays, because it has been shown that deep brain stimulation and insular tumor surgery can be performed by endovascular treatment, the importance of the vascular anatomy of the basal ganglia is being increasingly recognized.

OBJECTIVE

To explain the arterial blood supply of the basal ganglia using white matter dissection.

METHODS

The Klingler protocol was used to prepare 12 silicone-injected human hemispheres. The dissections were performed from lateral to medial with the fiber dissection technique to preserve arteries.

RESULTS

The globus pallidus blood supply came from the medial lenticulostriate, lateral lenticulostriate, and anterior choroidal arteries; the substantia nigra and subthalamic nucleus were supplied by the branches of posterior cerebral artery; the putamen was supplied by the lateral and medial lenticulostriate arteries; and the caudate nucleus was supplied by the lateral lenticulostriate and medial lenticulostriate arteries and the recurrent artery of Heubner.

CONCLUSION

Knowledge of the detailed anatomy of the basal ganglia and its vascular supply is essential for avoiding postoperative ischemic complications in surgeries related to the insula. In addition, knowledge of this anatomy and vascular relationship opens the doors to endovascular deep brain stimulation treatment. This study provides a 3-dimensional understanding of the blood supply to the basal ganglia by examining it using the fiber dissection technique. Further studies could use advanced imaging modalities to explore the vascular relationships with critical structures in the brain.

A Review on the Surgical Management of Insular Gliomas

The surgical treatment of insular gliomas requires specialized knowledge. Over the last three decades, increased momentum in surgical resection of insular gliomas shifted the focus from one of expectant management to maximal safe resection to establish a diagnosis, characterize tumor genetics, treat preoperative symptoms (i.e., seizures), and delay malignant transformation through tumor cytoreduction. A comprehensive review of the literature was performed regarding insular glioma classification/genetics, insular anatomy, surgical approaches, and patient outcomes. Modern large, published series of insular resections have reported a median 80% resection, 80% improvement in preoperative seizures, and postsurgical permanent neurologic deficits of less than 10%. Major complication avoidance includes recognition and preservation of eloquent cortex for language and respecting the lateral lenticulostriate arteries.

Surgical management of an abscess of the insula

Background

Mass lesions within the insular are diagnostically and surgically challenging due to the numerous critical cortical, subcortical, and vascular structures surrounding the region. Two main surgical techniques - the transsylvian approach and the transcortical approach - provide access to the insular cortex. Of the range of pathologies encountered, abscesses in the insula are surprisingly rare.

Case Description

A 34-year-old patient was admitted for surgical resection of a suspected high-grade glioma in the insula of the dominant hemisphere. A rapid clinical decline prompted emergent neurosurgical intervention using a transsylvian approach. Surprisingly, abundant purulent material was encountered on entering the insular fossa. Pathological analysis confirmed an insular abscess, although a source of infection could not be identified. The patient required a second evacuation for reaccumulation of the abscess and adjuvant corticosteroids for extensive cerebral edema.

Conclusion

An abscess located in the insular cortex is an incredibly rare occurrence. Surgical management using the transsylvian approach is one option to approach this region. Familiarity with this approach is thus extremely beneficial in situations requiring emergent access to the dominant insula when awake mapping is not feasible. In addition, treatment of abscesses with adjuvant corticosteroids is indicated when extensive, life-threatening cerebral edema is present.

Association of Lesion Topography with Functional Outcomes in Acute Ischemic Stroke Patients Considered for, or Receiving, Reperfusion Therapy: A Meta-Analysis

Background: The impact of lesion topography (LT), characterised by the Alberta Stroke Programme Early CT Score (ASPECTS), on outcomes after reperfusion therapy in acute ischemic stroke (AIS) is poorly elucidated. We investigated the prognostic accuracy of ASPECTS-based LT assessment and its association with clinical outcomes in AIS patients considered for reperfusion therapy or receiving intravenous thrombolysis (IVT), endovascular thrombectomy (EVT), or none or both. Methods: Studies were identified from PubMed with additional studies added from Google Scholar. The prevalence of individual ASPECTS regions will also be determined. The association of individual ASPECTS regions with the functional outcome at 90 days will be assessed using random-effects modelling for various cut-offs, such as 6, 7 and 8. The association of continuous ASPECTS with the functional outcome at 90 days will also be undertaken. Forest plots of odds ratios (ORs) will be generated. Results: A total of 25 studies have been included in the final analysis, encompassing 11,404 patients. Pooled estimates indicate that the highest prevalence rates were in cases involving the insula and lentiform nucleus. Subgroup analysis for ASPECTS < 6 (OR 6.10; 95% CI 2.50−14.90; p < 0.0001), ASPECTS < 7 (OR 4.58; 95% CI 1.18−17.86; p < 0.0001) and ASPECTS < 8 (OR 2.26; 95% CI 1.32−3.89; p < 0.0001) revealed a significant association with poor functional outcome at 90 days. Decreasing ASPECTS significantly increased the odds of poor functional outcomes at 90 days (SMD −1.15; 95% CI −1.77−−0.52; p < 0.0001). Conclusions: Our meta-analysis demonstrates that decreasing ASPECTS is significantly associated with poor functional outcomes. Individual ASPECTS regions associated with the highest odds of poor functional outcomes were identified. Future studies on the association of LT and clinical outcomes specific to EVT are required.

Incidence of ischemic complications and technical nuances of arteries preservation for insular gliomas resection

Introduction

Insular gliomas have complex anatomy and microvascular supply that make resection difficult. Furthermore, resection of insular glioma is associated with a significant risk of postoperative ischemic complications. Thus, this study aimed to assess the incidence of ischemic complications related to insular glioma resection, determine its risk factors, and describe a single surgeon's experience of artery-preserving tumor resection.

Methods

We enrolled 75 consecutive patients with insular gliomas who underwent transcortical tumor resection. Preoperative and postoperative demographic, clinical, radiological [including diffusion-weighted imaging (DWI)], intraoperative neurophysiological data, and functional outcomes were analyzed. Motor evoked potentials (MEPs) and radiological characteristics like the relationship between the proximal segment of the lateral lenticulostriate arteries (LLSAs) and the tumor, the flat inner edge sign (the inner edge of the insular glioma is well-defined) or obscure inner edge sign, the distance between the lesion and posterior limb of the internal capsule and the invasion of the superior limiting sulcus by the tumor were analyzed. Strategies such as "residual triangle," "basal ganglia outline reappearance," and "sculpting" technique were used to preserve the LLSAs and the main branches of M2 for maximal tumor resection according to the Berger-Sinai classification.

Results

Postoperative DWI showed acute ischemia in 44 patients (58.7%). Moreover, nine patients (12%) had developed new motor deficits, as determined by the treating neurosurgeons. The flat inner edge sign [odds ratio (OR), 0.144; 95% confidence interval (CI), 0.024-0.876) and MEPs (>50%) (OR, 18.182; 95% CI, 3.311-100.00) were significantly associated with postoperative core ischemia, which affected the posterior limb of the internal capsule or corona radiata.

Conclusions

Insular glioma resection was associated with a high incidence of ischemia, as detected by DWI, as well as new motor deficits that were determined by the treating neurosurgeons. Insular glioma patients with obscure inner edge signs and intraoperative MEPs decline >50% had a higher risk of developing core ischemia. With our strategies, maximal safe resection of insular gliomas may be achieved.

Seizure outcome after resection of insular glioma: a systematic review, meta-analysis, and institutional experience

OBJECTIVE

Gliomas arising from the insular cortex can be epileptogenic, with a significant proportion of patients having medically refractory epilepsy. The impact of surgery on seizure control for such tumors is not well established. In this study, the authors aimed to investigate seizure outcomes after resection of insular gliomas using a meta-analysis and institutional experience.

METHODS

Three databases (Ovid MEDLINE, Embase, and Cochrane Central Register of Controlled Trials) were systematically searched for published studies of seizure outcomes after insular glioma resection from database inception to March 27, 2021. In addition, data were retrospectively collected on all adults (age > 17 years) who had undergone insular glioma resection between June 1997 and June 2015 at the authors' institution. Primary outcome measures were seizure freedom rates at 1 year and the last follow-up. Secondary outcome measures consisted of persistent postoperative neurological deficit beyond 90 days, mortality, and tumor progression or recurrence.

RESULTS

Eight studies reporting on 453 patients who had undergone 460 operations were included in the meta-analysis. The pooled mean age of the patients was 42 years. The pooled percentages of patients with extents of resection (EORs) ≥ 90%, 70%-89%, and < 70% were 55%, 33%, and 11%, respectively. The pooled seizure freedom rate at 1 year was 73% for Engel class IA and 78% for Engel class I. The pooled seizure freedom rate at the last follow-up was 60% for Engel class IA and 79% for Engel class I. The pooled percentage of persistent neurological deficit beyond 90 days was 3%. At the authors' institution, 109 patients had undergone resection of insular glioma. A greater EOR was the only significant independent predictor of seizure freedom after surgery (HR 0.290, p = 0.017). The optimal threshold for seizure freedom corresponded to an EOR of 81%. Patients with an EOR > 81% had a significantly higher seizure freedom rate (OR 2.16, p = 0.048).

CONCLUSIONS

Maximal safe resection can be performed with minimal surgical morbidity to achieve favorable seizure freedom rates in both the short and long term. When gross-total resection is not possible, an EOR > 81% confers the greatest sensitivity and specificity for achieving seizure freedom. Systematic review registration no.: CRD42021249404 (https://www.crd.york.ac.uk/prospero/).

Avoiding vascular complications in insular glioma surgery – A microsurgical anatomy study and critical reflections regarding intraoperative findings

Introduction

Vascular lesions in insular glioma surgery can severely impact patients&amp;apos; quality of life. This study aims to present the results of our dissections and authors’ reflections on the insular vascular anatomy.

Matherials and Methods

The insular vascularization was examined using ×3 to ×40 magnification in 20 cadaveric cerebral hemispheres in which the arteries and veins had been perfused with colored silicone.

Results

In insular gliomas, this individualization of the anatomical structures is rarely possible, as the gyri are swollen by the tumor and lose their individuality. In the transsylvian approaches, the anatomical parameters for delimiting the insula in tumors are best provided by the superior and inferior circular sulci. The branches of the MCA are easily identified in the transcortical approach, but only at the end of the surgery after the tumor is resected.). One of the factors under-discussed in the literature is the involvement of the lenticulostriate arteries by the medial part of the tumor. In our experience of 52 patients (article submitted to publishing), LSTa were founded to be involved by the tumor in 13 cases. In 39 patients, there was no involvement of the LSTa, which allowed a more aggressive resection. Early preoperative identification of the anterior perforated substance on the MRI and its proximity to the tumor may help determine the route of the LSTa over the medial tumor boundaries.

Discussion

Our reflections introduced our imaging and anatomical concept regarding LSTa in insular glioma surgery. Accurate identification of origin, route, and distribution of the LSTa is pivotal to surgical success, especially in the lateral group. The anatomical knowledge of their path directly impacts the extent of tumor resection and functional preservation.

Conclusion

Knowledge of microsurgical anatomy, brain mapping, and surgical experience counts a lot in this type of surgery, creating a reasonable procedure flowchart to be taken intraoperatively.

Anatomo-functional evaluation for management and surgical treatment of insular cavernous malformation: a case series

BACKGROUND

Insular cavernous malformations (iCMs) are very rare vascular lesions. Their surgical management is challenging, due to their complex functional and vascular relationship. The continuous improvement of intra-operative tools and neuroimaging techniques has progressively enhanced the safety of iCM surgery. Nevertheless, the best surgical approach remains controversial.

OBJECTIVE

To analyze the potential role of an anatomo-functional classification to guide the iCMs' management.

METHODS

The study included patients affected by iCMs and referred to the Senior Author (FA). All cases were divided in 2 groups, according to a mainly pial growth pattern (exophytic group) or a subcortical one (endophytic group). Endophytic iCM was further subdivided in 3 subgroups, based on the insular gyri involved. According to this classification, each patient underwent a specific additional neuroimaging investigation and surgical evaluation.

RESULTS

A total of 24 patients were included. In the surgical group, trans-sylvian (TS) approach was used in 6 patients with exophytic or Zone I endophytic iCMs. The transcortical (TC) approach with awake monitoring was used in 6 cases of Zone II endophytic vascular lesions. Both TS and trans-intraparietal sulcal (TIS) approach were used for 3 cases of Zone III endophytic iCM. At follow-up, 3 patients were fully recovered from a transient speech impairment while a permanent morbidity was observed in one case.

CONCLUSIONS

ICMs represent a single entity with peculiar clinical and surgical aspects. The proposed iCM classification focuses on anatomical and functional concerns, aiming to suggest the best pre-operative work-up and the surgical evaluation.

Post-operative Corona Radiata Infarct in a High-flow EC-IC Bypass: Report of Unusual Complication

Long insular artery (LIA) infarct can occur after insular glioma surgery. LIA infarct after extracranial-intracranial (EC-IC) bypass is very rare, and so far, it is not reported in EC-IC bypass. Here, we report a case of high-flow EC-IC bypass, where postoperatively, the patient developed isolated LIA infarct. A 65-year-old female presented with recurrent severe headache along with altered sensorium. Computed tomography (CT) scan and CT angiography (CTA) of the brain showed ruptured large left internal carotid artery (ICA) fusiform aneurysm. She underwent left-sided, high-flow EC-IC bypass involving upper trunk of left middle cerebral artery (MCA) and ICA ligation at neck at its origin. Postoperatively, the patient developed right sided hemiplegia. Postoperative MRI of the brain showed left-sided external capsular infarct, extending up to the corona radiata resulted from LIA infarct. By the end of 6 months after operation, she could walk with support but her left upper limb remained more severely affected and magnetic resonance angiogram (MRA) showed almost disappearance of aneurysm with functioning bypass.

Drug resistant epilepsy of the insular lobe: A review and update article

Background:

Epilepsy is a chronic disease that affects millions of people around the world generating great expenses and psychosocial problems burdening the public health in different ways. A considerable number of patients are refractory to the drug treatment requiring a more detailed and specialized investigation to establish the most appropriate therapeutic option. Insular epilepsy is a rare form of focal epilepsy commonly drug resistant and has much of its investigation and treatment involved with the surgical management at some point. The insula or the insular lobe is a portion of the cerebral cortex located in the depth of the lateral sulcus of the brain; its triangular in shape and connects with the other adjacent lobes. The insular lobe is a very interesting and complex portion of the brain related with different functions. Insula in Latin means Island and was initially described in the 18^th century but its relation with epilepsy was first reported in the 1940–1950s. Insular lobe epilepsy is generally difficult to identify and confirm due to its depth and interconnections. Initial non-invasive studies generally demonstrate frustrating or incoherent information about the origin of the ictal event. Technological evolution made this pathology to be progressively better recognized and understood enabling professionals to perform the correct diagnosis and choose the ideal treatment for the affected population.

Methods:

A literature review was performed using MEDLINE/PubMed, Scopus, and Web of Science databases. The terms epilepsy/epileptic seizure of the insula and surgical treatment was used in various combinations. We included studies that were published in English, French, or Portuguese; performed in humans with insular epilepsy who underwent some surgical treatment (microsurgery, laser ablation, or radiofrequency thermocoagulation).

Results:

Initial search results in 1267 articles. After removing the duplicates 710 remaining articles were analyzed for titles and abstracts applying the inclusion and exclusion criteria. 70 studies met all inclusion criteria and were selected.

Conclusion:

At present, the main interests and efforts are in the attempt to achieve and standardize the adequate management of the patient with refractory epilepsy of the insular lobe and for that purpose several forms of investigation and treatment were developed. In this paper, we will discuss the characteristics and information regarding the pathology and gather data to identify and choose the best therapeutic option for each case.

Subjective Well-Being and Bilateral Anterior Insula Functional Connectivity After Exercise Intervention in Older Adults With Mild Cognitive Impairment

While it is well known that exercise training is associated with improvement in subjective well-being among older adults, it is unclear if individuals with cognitive impairment experience the same effects elicited by exercise on subjective well-being. We further explored whether the bilateral anterior insula network may be an underlying neural mechanism for the exercise training-related improvements in subjective well-being. We investigated the effects of exercise training on subjective well-being in older adults (78.4 ± 7.1 years) with mild cognitive impairment (MCI; n = 14) and a cognitively normal (CN; n = 14) control group. We specifically assessed the relationship between changes in subjective well-being and changes in functional connectivity (FC) with the bilateral anterior insula from before to after exercise training. Cardiorespiratory fitness, subjective well-being, and resting-state fMRI were measured before and after a 12-week moderate-intensity walking intervention. A seed-based correlation analysis was conducted using the bilateral anterior insula as a priori seed regions of interest. The associations between bilateral anterior insula FC with other brain regions and subjective well-being were computed before and after exercise training, respectively, and the statistical difference between the correlations (before vs after exercise training) was evaluated. There was a significant Group (MCI vs CN) × Time (before vs after exercise training) interaction for subjective well-being, such that while those with MCI demonstrated significantly increased subjective well-being after exercise training, no changes in subjective well-being were observed in CN. Participants with MCI also showed an exercise training-related increase in the bilateral anterior insula FC. While there was no significant correlation between subjective well-being and bilateral anterior insula FC before exercise training, a positive association between subjective well-being and bilateral anterior insula FC was found in the MCI group after exercise training. Our findings indicate that 12 weeks of exercise training may enhance subjective well-being in older adults diagnosed with MCI and, further, suggest that increased bilateral anterior insula FC with other cortical regions may reflect neural network plasticity associated with exercise training-related improvements in subjective well-being.

Surgical Anatomy of the Middle Communicating Artery and Guidelines for Predicting the Feasibility of M2-M2 End-to-End Reimplantation

BACKGROUND

M2-M2 end-to-end reimplantation that creates a middle communicating artery has recently been proposed as a reconstruction technique to treat complex aneurysms of the middle cerebral artery that are not amenable to clipping.

OBJECTIVE

To examine the surgical anatomy, define anatomic variables, and explore the feasibility of this bypass.

METHODS

Sixteen cadaver heads were prepared for bypass simulation. After the middle cerebral artery bifurcation was approached, the proximal insular (M2) segments and perforators were explored. To define the maximal distance between the M2 segments that allows the bypass to be performed, the M2 segments were mobilized and reimplanted in an end-to-end fashion.

RESULTS

Successful reimplantation was performed in all specimens. The mean maximal distance between the M2 segments to create the proposed reimplantation was 9.1 ± 3.2 mm. The mean vessel displacement was significantly greater for the superior (6.0 ± 2.3 mm) M2 segment than for the inferior (3.2 ± 1.4 mm) M2 segment (P < .001).

CONCLUSION

In this cadaveric study, the stumps of the M2 segments located at a distance of ≤9.1 mm could be approximated to create a feasible M2-M2 end-to-end anastomosis. Intraoperative inspection of the M2 segments and their perforators could allow further assessment of the feasibility of the procedure before final revascularization decisions are made.

Microsurgical Treatment of Deep and Eloquent AVMs

Over the past 30 years, the treatment of deep and eloquent arteriovenous malformations (AVMs) has moved away from microneurosurgical resection and towards medical management and the so-called minimally invasive techniques, such as endovascular embolization and radiosurgery. The Spetzler-Martin grading system (and subsequent modifications) has done much to aid in risk stratification for surgical intervention; however, the system does not predict the risk of hemorrhage nor risk from other interventions. In more recent years, the ARUBA trial has suggested that unruptured AVMs should be medically managed. In our experience, although these eloquent regions of the brain should be discussed with patients in assessing the risks and benefits of intervention, we believe each AVM should be assessed based on the characteristics of the patient and the angio-architecture of the AVM, in particular venous hypertension, which may guide us to treat even high-grade AVMs when we believe we can (and need to) to benefit the patient. Advances in imaging and intraoperative adjuncts have helped us in decision making, preoperative planning, and ensuring good outcomes for our patients. Here, we present several cases to illustrate our primary points that treating low-grade AVMs can be more difficult than treating high-grade ones, mismanagement of deep and eloquent AVMs at the behest of dogma can harm patients, and the treatment of any AVM should be tailored to the individual patient and that patient's lesion.

Awake Surgery for Left Posterior Insular Low-Grade Glioma Through the Parietorolandic Operculum: The Need to Preserve the Functional Connectivity. A Case Series

Objective: Surgical approach to low-grade glioma (LGG) involving the posterior insula is challenging, especially in the left hemisphere, with a high risk of sensorimotor, language, or visual deterioration. In this study, a case series of 5 right-handed patients harboring a left posterior insular LGG is reported, by detailing a transcorticosubcortical approach.

Method: The five surgeries were achieved in awake patients using cortical and axonal electrostimulation mapping. The glioma was removed through the left rolandic and/or parietal opercula, with preservation of the subcortical connectivity.

Results: The cortical mapping was positive in the five patients, enabling the selection of an optimal transcortical approach, via the anterolateral supramarginal gyrus in four patients and/or via the lateral retrocentral gyrus in three cases (plus through the left superior temporal gyrus in one case). Moreover, the white matter tracts were identified in all cases, i.e., the lateral part of the superior longitudinal fasciculus (five cases), the arcuate fasciculus (four cases), the thalamocortical somatosensory pathways (four cases), the motor pathway (one case), the semantic pathway (three cases), and the optic tract (one case). Complete resection of the LGG was achieved in two patients and near-total resection in three patients. There were no postoperative permanent sensorimotor, language, or visual deficits.

Conclusion: A transcortical approach through the parietorolandic operculum in awake patients represents safe and effective access to the left posterior insular LGG. Detection and preservation of the functional connectivity using direct electrostimulation of the white matter bundles are needed in this cross-road brain region to prevent otherwise predictable postsurgical impairments.

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 ​± ​0.37) as determined by 3D-TOF MRA and 2-6 (mean 4.25 ​± ​0.25) as determined intraoperatively, κ ​= ​0.51 (95% CI: 0.25-0.76) and τ ​= ​0.64 (p ​< ​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 ​= ​0.87 (95% CI: 0.70-1), τ ​= ​0.93 (p ​< ​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.

Complication avoidance: resection of the insular glioma complicated by iatrogenic injury to the lenticulostriate artery

BACKGROUND

Neurosurgical resection of insular gliomas is complicated by the risk of iatrogenic injury to lenticulostriate arteries (LSAs).

METHOD

We provide a description, figures, and a video to illustrate the clinical case in which the LSA was damaged during the resection of insular glioma. Cadaveric dissection from our anatomical laboratory and our 3D anatomical model provided relevant surgical anatomy of the insula.

CONCLUSION

Proximal dissection of the Sylvian fissure up to the most lateral LSA, the emergence of the beige putamen, and the lenticulostriate veins are anatomic landmarks that allow reducing the risk of damaging the intraparenchymatous segment of the LSAs.

Avoiding Complications in Surgical Resection of Insular Gliomas - Single Surgeon Experience

Background and Aims

Insular gliomas remain one of most challenging locations for aggressive resection. We report our experience and strategies we employed to avoid complications in immediate post-operative period of surgical resection of insular gliomas.

Methods

Retrospective analysis of data collected in 61 consecutive patients who underwent surgical resection of insular gliomas between May 2013 and May 2016 was done. Primary outcome measures were neurological deficits and death in the immediate post-operative period to three months follow-up.

Results

The average age of the study population was 42.57 ± 10.98 years with 41 (67.2%) men. Glioma was on the right side in 35 (57.3%) patients. Surgery for recurrent glioma was performed in three (4.9%) patients. The average MIB index of the entire group was 10.1 ± 13.9. While 23 (37.7%) patients underwent the TO approach, 38 (62.3%) underwent TS approach. In the immediate post-operative period, significantly higher number of patients under TS approach had post-surgical complications (8.6% vs 34.2%; P = 0.032). The surgical approaches did not differ significantly for outcome, mortality and complications at three month post-operatively (0.0% vs 10.5%; P = 0.287). However, a trend for lower complications at three months was observed with TO approach.

Conclusion

We report that morbidity and mortality in immediate post-operative period can be reduced by: a) pre-surgical assessment of confinement of glioma in respect to lenticulo-striate arteries, b) Intra-operative use of functional-MRI, DTI tractography and ICG angiography, c) Application of Berger-Sinai classification to localize the glioma, d) selecting either TS or TO approach based on Berger-Sinai classification.

Age-dependent Intracranial Artery Morphology in Healthy Children

PURPOSE

Evaluation of intracranial artery morphology plays an important role in diagnosing a variety of neurovascular diseases. In addition to clinical symptoms, diagnosis currently relies on qualitative rather than quantitative evaluation of vascular imaging sequences, such as magnetic resonance angiography (MRA). However, there is a paucity of literature on normal arterial morphology in the pediatric population across brain development. We aimed to quantitatively assess normal, age-related changes in artery morphology in children.

METHODS

We performed retrospective analysis of pediatric MRA data obtained from a tertiary referral center. An MRA dataset from 98 children (49 boys/49 girls) aged 0.6-20 years (median = 11.5 years) with normal intracranial vasculature was retrospectively collected between 2011 and 2018. All arteries were automatically segmented to determine the vessel radius. Using an atlas-based approach, the average radius and density of arteries were measured in the three main cerebral vascular territories and the radius of five major arteries was determined at corresponding locations.

RESULTS

The radii of the major arteries as well as the average artery radius and density in the different vascular territories in the brain remained constant throughout childhood and adolescence (|r| < 0.369 in all cases).

CONCLUSION

This study presents the first automated evaluation of intracranial vessel morphology on MRA across childhood. Our results can serve as a framework for quantitative evaluation of cerebral vessel morphology in the setting of pediatric neurovascular diseases.

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.

Anatomical aspects of the insula, opercula and peri-insular white matter for a transcortical approach to insular glioma resection

The insula is a lobe located deep in each hemisphere of the brain and is surrounded by eloquent cortical, white matter, and basal ganglia structures. The aim of this study was to provide an anatomical description of the insula and white matter tracts related to surgical treatment of gliomas through a transcortical approach. The study also discusses surgical implications in terms of intraoperative brain mapping. Five adult brains were prepared according to the Klingler technique. Cortical anatomy was evaluated with the naked eye, whereas white matter dissection was performed with the use of a microscope. The widest exposure of the insular surface was noted through the temporal operculum, mainly in zones III and IV according to the Berger-Sanai classification. By going through the pars triangularis in all cases, the anterior insular point and most of zone I were exposed. The narrowest and deepest operating field was observed by going through the parietal operculum. This method provided a suitable approach to zone II, where the corticospinal tract is not covered by the basal ganglia and is exposed just under the superior limiting sulcus. At the subcortical level, the identification of the inferior frontoocipital fasciculus at the level of the limen insulae is critical in terms of preserving the lenticulostriate arteries. Detailed knowledge of the anatomy of the insula and subcortical white matter that is exposed through each operculum is essential in preoperative planning as well as in the intraoperative decision-making process in terms of intraoperative brain mapping.

Integration of Microanatomy, Neuronavigation, Dynamic Neurophysiologic Monitoring, and Intraoperative Multimodality Imaging for the Safe Removal of an Insular Glioma: 2-Dimensional Operative Video

Insular gliomas are located amongst myriad critical neurovascular structures, including lenticulostriate vessels, long insular perforators, putamen, internal capsule, frontal and temporal opercula, and key fasciculi.1-6 Each of these critical structures engenders key function of the brain, which must be preserved. Although anatomic knowledge remains the cornerstone of insular glioma surgery, novel tools have been developed to aid the surgeon in identifying and preserving these essential structures. Modern surgery of the insular glioma calls for seamless integration of these techniques to maximize the safety and totality of insular glioma resection, which has been shown to improve length of survival and seizure control, while reducing risk of tumor transformation.7-10 Neuronavigation can be used to help plan the craniotomy to achieve adequate exposure and assist during tumor resection. Brain "shift" can be corrected by re-registration following intraoperative magnetic resonance imaging (MRI). Interval ultrasound imaging reflects real-time progressive tumor resection. Dynamic neurophysiologic monitoring using thresholding techniques guides the surgeon as he resects tumor at its depth and posterior pole-close to the internal capsule. Intraoperative magnetic resonance imaging depicts residual infiltrative tumor that may require additional resection. The patient is a 33-yr-old woman with progressive growth of a right insular tumor and has consented to surgery, photography, and video recording.  Figure at 1:57, © Ossama Al-Mefty, used with permission.

Robot-Assisted Insular Depth Electrode Implantation Through Oblique Trajectories: 3-Dimensional Anatomical Nuances, Technique, Accuracy, and Safety

BACKGROUND

The insula is a deep cortical structure that has renewed interest in epilepsy investigation. Invasive EEG recordings of this region have been challenging. Robot-assisted stereotactic electroencephalography has improved feasibility and safety of such procedures.

OBJECTIVE

To describe technical nuances of three-dimensional (3D) oblique trajectories for insular robot-assisted depth electrode implantation.

METHODS

Fifty patients who underwent robot-assisted depth electrode implantation between June 2017 and December 2018 were retrospectively analyzed. Insular electrodes were implanted through oblique, orthogonal, or parasagittal trajectories. Type of trajectories, accuracy, number of contacts within insular cortex, imaging, and complication rates were analyzed. Cadaveric and computerized tomography/magnetic resonance imaging 3D reconstructions were used to visualize insular anatomy and the technical implications of oblique trajectories.

RESULTS

Forty-one patients (98 insular electrodes) were included. Thirty (73.2%) patients had unilateral insular coverage. Average insular electrodes per patient was 2.4. The mean number of contacts was 7.1 (SD ± 2.91) for all trajectories and 8.3 (SD ± 1.51) for oblique insular trajectories. The most frequently used was the oblique trajectory (85 electrodes). Mean entry point error was 1.5 mm (0.2-2.8) and target error was 2.4 mm (0.8-4.0), 2.0 mm (1.1-2.9) for anterior oblique and 2.8 mm (0.8-4.9) for posterior oblique trajectories. There were no complications related to insular electrodes.

CONCLUSION

Oblique trajectories are the preferred method for insular investigation at our institution, maximizing the number of contacts within insular cortex without traversing through sulci or major CSF fissures. Robot-assisted procedures are safe and efficient. 3D understanding of the insula's unique anatomical features can help the surgeon to improve targeting of this structure.

Postcentral gyrus resection of opercular gliomas is a risk factor for motor deficits caused by damaging the radiologically invisible arteries supplying the descending motor pathway

BACKGROUND

Postoperative motor deficits are among the worst morbidities of glioma surgery. We aim to investigate factors associated with postoperative motor deficits in patients with frontoparietal opercular gliomas.

METHODS

Thirty-four patients with frontoparietal opercular gliomas were retrospectively investigated. We examined the postoperative ischemic changes and locations obtained from MRI.

RESULTS

Twenty-one patients (62%) presented postoperative ischemic changes. Postoperative MRI was featured with ischemic changes, all located at the subcortical area of the resection cavity. Six patients had postoperative motor deficits, whereas 28 patients did not. Compared to those without motor deficits, those with motor deficits were associated with old age, pre- and postcentral gyri resection, and postcentral gyrus resection (P = 0.023, 0,024, and 0.0060, respectively). A merged image of the resected cavity and T1-weighted brain atlas of the Montreal Neurological Institute showed that a critical area for postoperative motor deficits is the origin of the long insular arteries (LIAs) and the postcentral gyrus. Detail anatomical architecture created by the Human Connectome Project database and T2-weighted images showed that the subcortical area of the operculum of the postcentral gyrus is where the medullary arteries supply, and the motor pathways originated from the precentral gyrus run.

CONCLUSIONS

We verified that the origin of the LIAs could damage the descending motor pathways during the resection of frontoparietal opercular gliomas. Also, we identified that motor pathways run the subcortical area of the operculum of the postcentral gyrus, indicating that the postcentral gyrus is an unrecognized area of damaging the descending motor pathways.