Filling the gap: brief neuropsychological assessment protocol for glioma patients undergoing awake surgeries.

Introduction: The literature lacks a concise neurocognitive test for assessing primary cognitive domains in neuro-oncological patients. This study aims to describe and assess the feasibility of the Ohy-Maldaun Fast Track Cognitive Test (OMFTCT), used to pre- and post-operatively evaluate patients undergoing brain tumor surgery in language eloquent areas. The cognitive diagnosis was used to safely guide intraoperative language assessment. Methods: This is a prospective longitudinal observational clinical study conducted on a cohort of 50 glioma patients eligible for awake craniotomies. The proposed protocol assesses multiple cognitive domains, including language, short-term verbal and visual memories, working memory, praxis, executive functions, and calculation ability. The protocol comprises 10 different subtests, with a maximum score of 50 points, and was applied at three time points: preoperative, immediately postoperative period, and 30 days after surgery. Results: Among the initial 50 patients enrolled, 36 underwent assessment at all three designated time points. The mean age of the patients was 45.3 years, and they presented an average of 15 years of education. The predominant tumor types included Glioblastoma, IDH-wt (44.1%), and diffuse astrocytoma, IDH-mutant (41.2%). The tumors were located in the left temporal lobe (27.8%), followed by the left frontal lobe (25%). The full test had an average application time of 23 min. Conclusion: OMFTCT provided pre- and postoperative assessments of different cognitive domains, enabling more accurate planning of intraoperative language testing. Additionally, recognition of post-operative cognitive impairments played a crucial role in optimizing patient care.

Cortico-cortical evoked potential and language mapping: A meta-analysis.

PURPOSE: The purpose of this meta-analysis was to determine the best available evidence for the use of cortico-cortical evoked potential (CCEP) for language mapping. METHODS: PubMed/Medline/Google Scholar/Cochrane and Scopus electronic databases were searched for articles using CCEP for language mapping. CCEP data was obtained including the area of the cortex generating CCEP, resection data, and post-resection language outcomes. Inclusion criteria were clinical articles reporting the use of CCEP in language regions of the brain, reporting language outcomes and whether there was final resection of the cortex, studies with more than five patients, and studies in either English or Spanish. Review articles, systematic reviews, meta-analyses, or case series with less than five patients were excluded. RESULTS: Seven studies with a total of 59 patients were included in this meta-analysis. The presence of CCEPs from stimulation of Broca's area or posterior perisylvian region in the resection predicts language deficits after surgery. The diagnostic odds ratio shows values greater than 0 perioperatively (0.69-5.82) and after six months (1.38-11), supporting a high likelihood of a language deficit if the presence of CCEPs from stimulation of Broca's area or posterior perisylvian region are included in the resection and vice versa. The True Positive rate varied between 0.38 and 0.87. This effect decreases after six months to 0.61 (0.30-0.86). However, the True Negative rate increased from 0.53 (0.32-0.79) to 0.71 (0.55-0.88). CONCLUSION: This meta-analysis supports the utility of CCEP to predict the probability of having long-term language deficits after surgery. .

Frontal trans opercular approaches to the insula: building the mental picture from procedure-guided anatomical dissection.

BACKGROUND: Performing transopercular frontal approaches to the insula, widely used in glioma surgeries, necessitates a meticulous understanding of both cortical and subcortical neuroanatomy. This precision is vital for preserving essential structures and accurately interpreting the results of direct electrical stimulation. Nevertheless, acquiring a compelling mental image of the anatomy of this region can be challenging due to several factors, among which stand out its complexity and the fact that white matter fasciculi are imperceptible to the naked eye in the living brain. AIM: In an effort to optimize the study of the anatomy relevant to this topic, we performed a procedure-guided laboratory study using subpial dissection, fiber dissection, vascular coloration, and stereoscopic photography in a "real-life" surgical perspective. METHODS: Nine cerebral specimens obtained from body donation were extracted and fixed in formalin. Colored silicone injection and a variant of Klinglers's technique were used to demonstrate vascular and white matter structures, respectively. We dissected and photographed the specimens in a supero-antero-lateral view to reproduce the surgeon's viewpoint. The anatomy related to the development of the surgical corridor and resection cavity was documented using both standard photography and the red-cyan anaglyph technique. RESULTS: The anatomy of frontal transopercular approaches to the insula involved elements of different natures-leptomeningeal, cortical, vascular, and fascicular-combining in the surgical field in a complex disposition. The disposition of these structures was successfully demonstrated through the aforementioned anatomical techniques. Among the main structures in or around the surgical corridor, the orbital, triangular, and opercular portions of the inferior frontal gyrus are critical landmarks in the cortical stage, as well as the leptomeninges of the Sylvian fissure and the M2-M4 branches of the middle cerebral artery in the subpial dissection stage, and the inferior fronto-occipital, uncinate and arcuate fasciculi, and the corona radiata in establishing the deep limits of resection. CONCLUSIONS: Procedure-guided study of cerebral hemispheres associating subpial, vascular, and fiber dissection from a surgical standpoint is a powerful tool for the realistic study of the surgical anatomy relevant to frontal transopercular approaches to the insula.

Awake craniotomy with English and British sign language mapping in a patient with a left temporal glioblastoma reveals discordant speech-sign language maps.

The aim of this case study was to describe differences in English and British Sign Language (BSL) communication caused by a left temporal tumour resulting in discordant presentation of symptoms, intraoperative stimulation mapping during awake craniotomy and post-operative language abilities. We report the first case of a hearing child of deaf adults, who acquired BSL with English as a second language. The patient presented with English word finding difficulty, phonemic paraphasias, and reading and writing challenges, with BSL preserved. Intraoperatively, object naming and semantic fluency tasks were performed in English and BSL, revealing differential language maps for each modality. Post-operative assessment confirmed mild dysphasia for English with BSL preserved. These findings suggest that in hearing people who acquire a signed language as a first language, topographical organisation may differ to that of a second, spoken, language.

Spectrotemporal cortical dynamics and semantic control during sentence completion.

OBJECTIVE: To investigate cortical oscillations during a sentence completion task (SC) using magnetoencephalography (MEG), focusing on the semantic control network (SCN), its leftward asymmetry, and the effects of semantic control load. METHODS: Twenty right-handed adults underwent MEG while performing SC, consisting of low cloze (LC: multiple responses) and high cloze (HC: single response) stimuli. Spectrotemporal power modulations as event-related synchronizations (ERS) and desynchronizations (ERD) were analyzed: first, at the whole-brain level; second, in key SCN regions, posterior middle/inferior temporal gyri (pMTG/ITG) and inferior frontal gyri (IFG), under different semantic control loads. RESULTS: Three cortical response patterns emerged: early (0-200 ms) theta-band occipital ERS; intermediate (200-700 ms) semantic network alpha/beta-band ERD; late (700-3000 ms) dorsal language stream alpha/beta/gamma-band ERD. Under high semantic control load (LC), pMTG/ITG showed prolonged left-sided engagement (ERD) and right-sided inhibition (ERS). Left IFG exhibited heightened late (2500-2550 ms) beta-band ERD with increased semantic control load (LC vs. HC). CONCLUSIONS: SC involves distinct cortical responses and depends on the left IFG and asymmetric engagement of the pMTG/ITG for semantic control. SIGNIFICANCE: Future use of SC in neuromagnetic preoperative language mapping and for understanding the pathophysiology of language disorders in neurological conditions.

Analysis of bihemispheric language function in pediatric neurosurgical patients using repetitive navigated transcranial magnetic stimulation.

OBJECTIVE: Language dominance in the developing brain can vary widely across anatomical and pathological conditions as well as age groups. Repetitive navigated transcranial magnetic stimulation (rnTMS) has been applied to calculate the hemispheric dominance ratio (HDR) in adults. In this study, the authors aimed to assess the feasibility of using rnTMS to identify language lateralization in a pediatric neurosurgical cohort and to correlate the preoperative rnTMS findings with the postoperative language outcome. METHODS: A consecutive prospectively collected cohort of 19 children with language-associated lesions underwent bihemispheric rnTMS mapping prior to surgery (100 stimulation sites on each hemisphere). In addition to feasibility and adverse effects, the HDR (ratio of the left hemisphere to right hemisphere error rate) was calculated. The anatomical surgical site and postoperative language outcome at 3 months after surgery were assessed according to clinical documentation. RESULTS: Repetitive nTMS mapping was feasible in all 19 children (mean age 12.5 years, range 4-17 years; 16 left-sided lesions) without any relevant adverse events. Thirteen children (68%) showed left hemispheric dominance (HDR > 1.1), and 2 children (11%) showed right hemispheric dominance (HDR < 0.9). In 4 children (21%), the bihemispheric error rates were nearly the same (HDR ≥ 0.9 and ≤ 1.1). Sixteen children underwent surgery (14 tumor/lesion resections and 2 hemispherotomies) and 3 patients continued conservative therapy. After surgery, 4 patients (25%) showed an improvement in language function, 10 (63%) presented with stable language function, and 2 (12.5%) experienced deterioration in language function. Of the 6 patients with right hemispheric language involvement, 4 (80%) had glial tumors, 1 (20%) had focal cortical dysplasia, and 1 (20%) experienced hypoxic brain injury. Children with right hemispheric language involvement (HDR ≤ 1.1) did not show any language deterioration postoperatively. CONCLUSIONS: Bihemispheric rnTMS language mapping as a noninvasive mapping technique to assess lateralization of language function in the pediatric neurosurgical population is safe and feasible. Why relevant right hemispheric language function (HDR ≤ 1.1) was associated with postoperative unaltered language function needs to be validated in future studies. Bihemispheric rnTMS language mapping strengthens risk-benefit considerations prior to pediatric tumor/epilepsy surgery in language-associated areas.

Concordance between Wada, Transcranial Magnetic Stimulation, and Magnetoencephalography for Determining Hemispheric Dominance for Language: A Retrospective Study.

Determination of language hemispheric dominance (HD) in patients undergoing evaluation for epilepsy surgery has traditionally relied on the sodium amobarbital (Wada) test. The emergence of non-invasive methods for determining language laterality has increasingly shown to be a viable alternative. In this study, we assessed the efficacy of transcranial magnetic stimulation (TMS) and magnetoencephalography (MEG), compared to the Wada test, in determining language HD in a sample of 12 patients. TMS-induced speech errors were classified as speech arrest, semantic, or performance errors, and the HD was based on the total number of errors in each hemisphere with equal weighting of all errors (classic) and with a higher weighting of speech arrests and semantic errors (weighted). Using MEG, HD for language was based on the spatial extent of long-latency activity sources localized to receptive language regions. Based on the classic and weighted language laterality index (LI) in 12 patients, TMS was concordant with the Wada in 58.33% and 66.67% of patients, respectively. In eight patients, MEG language mapping was deemed conclusive, with a concordance rate of 75% with the Wada test. Our results indicate that TMS and MEG have moderate and strong agreement, respectively, with the Wada test, suggesting they could be used as non-invasive substitutes.

Function-guided differences of arcuate fascicle and inferior fronto-occipital fascicle tractography as diagnostic indicators for surgical risk stratification.

BACKGROUND: Several patients with language-eloquent gliomas face language deterioration postoperatively. Persistent aphasia is frequently associated with damage to subcortical language pathways. Underlying mechanisms still need to be better understood, complicating preoperative risk assessment. This study compared qualitative and quantitative functionally relevant subcortical differences pre- and directly postoperatively in glioma patients with and without aphasia. METHODS: Language-relevant cortical sites were defined using navigated transcranial magnetic stimulation (nTMS) language mapping in 74 patients between 07/2016 and 07/2019. Post-hoc nTMS-based diffusion tensor imaging tractography was used to compare a tract's pre- and postoperative visualization, volume and fractional anisotropy (FA), and the preoperative distance between tract and lesion and postoperative overlap with the resection cavity between the following groups: no aphasia (NoA), tumor- or previous resection induced aphasia persistent pre- and postoperatively (TIA_P), and surgery-induced transient or permanent aphasia (SIA_T or SIA_P). RESULTS: Patients with NoA, TIA_P, SIA_T, and SIA_P showed distinct fasciculus arcuatus (AF) and inferior-fronto-occipital fasciculus (IFOF) properties. The AF was more frequently reconstructable, and the FA of IFOF was higher in NoA than TIA_P cases (all p ≤ 0.03). Simultaneously, SIA_T cases showed higher IFOF fractional anisotropy than TIA_P cases (p < 0.001) and the most considerable AF volume loss overall. While not statistically significant, the four SIA_P cases showed complete loss of ventral language streams postoperatively, the highest resection-cavity-AF-overlap, and the shortest AF to tumor distance. CONCLUSION: Functionally relevant qualitative and quantitative differences in AF and IFOF provide a pre- and postoperative pathophysiological and clinically relevant diagnostic indicator that supports surgical risk stratification.

Speech and lexico-semantic errors during direct cortical stimulation mapping of the language-dominant hemisphere: effects of object and action naming.

OBJECTIVE: In this retrospective study, the authors aimed to establish the stereotactically defined probability distribution for speech (i.e., anarthria, speech arrest) and lexico-semantic errors (i.e., anomia) through direct cortical stimulation (DCS) by using two tasks: action naming and object naming. They also analyzed the patterns of interindividual variability in the localization of the language sites involved, and investigated whether any patient or lesion location factors were associated with greater variability. METHODS: Eighty-one Italian-speaking patients who underwent awake surgery between 2010 and 2021 for low- and high-grade gliomas in eloquent areas of the language-dominant hemisphere were entered in the analyses. The intraoperative DCS protocol included automatic speech tasks, object naming, and action naming. The position of the tags, as depicted on the intraoperative video or photograph, was transposed into Montreal Neurological Institute space. Subsequently, a 2D scatterplot and cluster analysis were performed. Associations between various clinical and radiological characteristics and the quantity of positive stimulated sites were determined by univariate analyses using binary logistic regression. Associated variables (p < 0.2) were included in stepwise multivariate logistic regression with backward elimination (p < 0.05). RESULTS: A total of 1380 cortical sites were stimulated, with a positive response in 511 cases (37%). Most anarthric errors were triggered when stimulating the left precentral gyrus, and most speech arrest errors were elicited when stimulating the left posterior inferior frontal gyrus. Anomias were found in the left inferior frontal gyrus and in the posterior part of the left temporal lobe for object naming. DCS to the left dorsal premotor cortex elicited anomic errors for action naming. Anomias were also elicited during DCS to the left posterior temporal lobe, with both object and action naming. CONCLUSIONS: The distribution of speech and lexico-semantic errors is in line with the current literature. The action-naming results are new and mostly involve the dorsal premotor cortex. These findings stress the importance of maximizing the use of different language tasks during surgery, because even when looking for the same type of errors, different tasks may be better suited to map specific brain regions. DCS with action and object naming identifies more positive sites than object naming alone.

CompreTAP: Feasibility and reliability of a new language comprehension mapping task via preoperative navigated transcranial magnetic stimulation.

OBJECTIVE: Stimulation-based language mapping approaches that are used pre- and intraoperatively employ predominantly overt language tasks requiring sufficient language production abilities. Yet, these production-based setups are often not feasible in brain tumor patients with severe expressive aphasia. This pilot study evaluated the feasibility and reliability of a newly developed language comprehension task with preoperative navigated transcranial magnetic stimulation (nTMS). METHODS: Fifteen healthy subjects and six brain tumor patients with severe expressive aphasia unable to perform classic overt naming tasks underwent preoperative nTMS language mapping based on an auditory single-word Comprehension TAsk for Perioperative mapping (CompreTAP). Comprehension was probed by button-press responses to auditory stimuli, hence not requiring overt language responses. Positive comprehension areas were identified when stimulation elicited an incorrect or delayed button press. Error categories, case-wise cortical error rate distribution and inter-rater reliability between two experienced specialists were examined. RESULTS: Overall, the new setup showed to be feasible. Comprehension-disruptions induced by nTMS manifested in no responses, delayed or hesitant responses, searching behavior or selection of wrong target items across all patients and controls and could be performed even in patients with severe expressive aphasia. The analysis agreement between both specialists was substantial for classifying comprehension-positive and -negative sites. Extensive left-hemispheric individual cortical comprehension sites were identified for all patients. Apart from one case presenting with transient worsening of aphasic symptoms, pre-existing language deficits did not aggravate if results were used for subsequent surgical planning. CONCLUSION: Employing this new comprehension-based nTMS setup allowed to identify language relevant cortical sites in all healthy subjects and severely aphasic patients who were thus far precluded from classic production-based mapping. This pilot study, moreover, provides first indications that the CompreTAP mapping results may support the preservation of residual language function if used for subsequent surgical planning.

Improving specificity of stimulation-based language mapping in stuttering glioma patients: A mixed methods serial case study.

Objective: Stimulation-based language mapping relies on identifying stimulation-induced language disruptions, which preexisting speech disorders affecting the laryngeal and orofacial speech system can confound. This study ascertained the effects of preexisting stuttering on pre- and intraoperative language mapping to improve the reliability and specificity of established language mapping protocols in the context of speech fluency disorders. Method: Differentiation-ability of a speech therapist and two experienced nrTMS examiners between stuttering symptoms and stimulation-induced language errors during preoperative mappings were retrospectively compared (05/2018-01/2021). Subsequently, the impact of stuttering on intraoperative mappings was evaluated in all prospective patients (01/2021-12/2022). Results: In the first part, 4.85 % of 103 glioma patients stuttered. While both examiners had a significant agreement for misclassifying pauses in speech flow and prolongations (Κ ≥ 0.50, p ≤ 0.02, respectively), less experience resulted in more misclassified stuttering symptoms. In one awake surgery case within the second part, stuttering decreased the reliability of intraoperative language mapping.Comparison with Existing Method(s): By thoroughly differentiating speech fluency symptoms from stimulation-induced disruptions, the reliability and proportion of stuttering symptoms falsely attributed to stimulation-induced language network disruptions can be improved. This may increase the consistency and specificity of language mapping results in stuttering glioma patients. Conclusions: Preexisting stuttering negatively impacted language mapping specificity. Thus, surgical planning and the functional outcome may benefit substantially from thoroughly differentiating speech fluency symptoms from stimulation-induced disruptions by trained specialists.

Language lateralization mapping (reversibly) masked by non-dominant focal epilepsy: a case report.

Language lateralization in patients with focal epilepsy frequently diverges from the left-lateralized pattern that prevails in healthy right-handed people, but the mechanistic explanations are still a matter of debate. Here, we debate the complex interaction between focal epilepsy, language lateralization, and functional neuroimaging techniques by introducing the case of a right-handed patient with unaware focal seizures preceded by aphasia, in whom video-EEG and PET examination suggested the presence of focal cortical dysplasia in the right superior temporal gyrus, despite a normal structural MRI. The functional MRI for language was inconclusive, and the neuropsychological evaluation showed mild deficits in language functions. A bilateral stereo-EEG was proposed confirming the right superior temporal gyrus origin of seizures, revealing how ictal aphasia emerged only once seizures propagated to the left superior temporal gyrus and confirming, by cortical mapping, the left lateralization of the posterior language region. Stereo-EEG-guided radiofrequency thermocoagulations of the (right) focal cortical dysplasia not only reduced seizure frequency but led to the normalization of the neuropsychological assessment and the "restoring" of a classical left-lateralized functional MRI pattern of language. This representative case demonstrates that epileptiform activity in the superior temporal gyrus can interfere with the functioning of the contralateral homologous cortex and its associated network. In the case of presurgical evaluation in patients with epilepsy, this interference effect must be carefully taken into consideration. The multimodal language lateralization assessment reported for this patient further suggests the sensitivity of different explorations to this interference effect. Finally, the neuropsychological and functional MRI changes after thermocoagulations provide unique cues on the network pathophysiology of focal cortical dysplasia and the role of diverse techniques in indexing language lateralization in complex scenarios.

Independent component analysis: a reliable alternative to general linear model for task-based fMRI.

Background: Functional magnetic resonance imaging (fMRI) is a valuable tool for the presurgical evaluation of patients undergoing neurosurgeries. Although many pre-processing steps have been modified according to advances in recent years, statistical analysis has remained largely the same since the first days of fMRI. In this study, we examined the ability of Independent Component Analysis (ICA) to separate the activation of a language task in fMRI, and we compared it with the results of the General Lineal Model (GLM). Methods: Sixty patients undergoing evaluation for brain surgery due to various brain lesions and/or epilepsy and 20 control subjects completed an fMRI language mapping protocol that included three tasks, resulting in 259 fMRI scans. Depending on brain lesion characteristics, patients were allocated to (1) static/chronic not-expanding lesions (Group 1) and (2) progressive/expanding lesions (Group 2). GLM and ICA statistical maps were evaluated by fMRI experts to assess the performance of each technique. Results: In the control group, ICA and GLM maps were similar without any superiority of either technique. In Group 1 and Group 2, ICA performed statistically better than GLM, with a p-value of < 0.01801 and < 0.0237, respectively. This indicated that ICA performs as well as GLM when the subjects are able to cooperate well (less movement, good task performance), but ICA could outperform GLM in the patient groups. When both techniques were combined, 240 out of 259 scans produced reliable results, showing that the sensitivity of task-based fMRI can be increased when both techniques are integrated with the clinical setup. Conclusion: ICA may be slightly more advantageous, compared to GLM, in patients with brain lesions, across the range of pathologies included in our population and independent of symptoms chronicity. Our findings suggest that GLM analysis may be more susceptible to brain activity perturbations induced by a variety of lesions or scanner-induced artifacts due to motion or other factors. In our research, we demonstrated that ICA is able to provide fMRI results that can be used in surgery, taking into account patient and task-wise aspects that differ from those when fMRI is used in research.

Interindividual variability and consistency of language mapping paradigms for presurgical use.

Most functional MRI studies of language processing have focussed on group-level inference, but for clinical use, the aim is to predict outcomes at an individual patient level. This requires being able to identify atypical activation and understand how differences relate to language outcomes. A language mapping paradigm that selectively activates left hemisphere language regions in healthy individuals allows atypical activation in a patient to be more easily identified. We investigated the interindividual variability and consistency of language activation in 12 healthy participants using three tasks-verb generation, responsive naming, and sentence comprehension-for future presurgical use. Responsive naming produced the most consistent left-lateralised activation across participants in frontal and temporal regions that postsurgical voxel-based lesion-symptom mapping studies suggest are most critical for language outcomes. Studies with a long-term clinical aim of predicting language outcomes in neurosurgical patients and stroke patients should first establish paradigm validity at an individual level in healthy participants.

Navigated Transcranial Magnetic Stimulation (nTMS) based Preoperative Planning for Brain Tumor Treatment.

Transcranial Magnetic Stimulation (TMS) is a non-invasive technique for analyzing the central and peripheral nervous system. TMS could be a powerful therapeutic technique for neurological disorders. TMS has also shown potential in treating various neurophysiological complications, such as depression, anxiety, and obsessive-compulsive disorders, without pain and analgesics. Despite advancements in diagnosis and treatment, there has been an increase in the prevalence of brain cancer globally. For surgical planning, mapping brain tumors has proven challenging, particularly those localized in expressive regions. Preoperative brain tumor mapping may lower the possibility of postoperative morbidity in surrounding areas. A navigated TMS (nTMS) uses magnetic resonance imaging (MRI) to enable precise mapping during navigated brain stimulation. The resulting magnetic impulses can be precisely applied to the target spot in the cortical region by employing nTMS. This review focuses on nTMS for preoperative planning for brain cancer. This study reviews several studies on TMS and its subtypes in treating cancer and surgical planning. nTMS gives wider and improved dimensions of preoperative planning of the motor-eloquent areas in brain tumor patients. nTMS also predicts postoperative neurological deficits, which might be helpful in counseling patients. nTMS have the potential for finding possible abnormalities in the motor cortex areas.

Neuropsychological outcomes after epilepsy surgery: A comparison of stereo electroencephalography and subdural electrodes.

BACKGROUND AND PURPOSE: We analyzed the association of neuropsychological outcomes after epilepsy surgery with the intracranial electrode type (stereo electroencephalography [SEEG] and subdural electrodes [SDE]), and electrical stimulation mapping (ESM) of speech/language. METHODS: Drug-resistant epilepsy patients who underwent comprehensive neuropsychological evaluation before and 1 year after epilepsy surgery were included. SEEG and SDE subgroups were matched by age, handedness, operated hemisphere, and seizure freedom. Postsurgical neuropsychological outcomes (adjusted for presurgical scores) and reliable change indices were analyzed as functions of electrode type and ESM. RESULTS: Ninety-nine patients aged 6-29 years were included with similar surgical resection/ablation volumes in the SEEG and SDE subgroups. Most of the neuropsychological outcomes were comparable between SEEG and SDE subgroups; however, Working Memory and Processing Speed were significantly improved in the SEEG subgroup. Undergoing language ESM was associated with significant improvements in Spelling, Letter-Word Identification, Vocabulary, Verbal Comprehension, Verbal Learning, and Story Memory scores, but a decline in Calculation scores. CONCLUSIONS: Intracranial evaluations with SEEG and SDE are comparable in terms of long-term postsurgical neuropsychological outcomes. Our data suggest that SEEG may be associated with improvements in working memory and processing speed, representing cognitive domains served by spatially distributed networks. Our study also supports wider use of language ESM before epilepsy surgery, preferably using other language tasks in addition to visual naming. Rather than the type of electrode, postsurgical neuropsychological outcomes are driven by whether language ESM was performed or not, with beneficial effects of language mapping.

Intraoperative Testing During the Mapping of the Language Cortex.

Intracranial lesions, particularly in the language-eloquent areas of the brain, can affect one's speaking ability. Despite advances in surgery, the excision of these lesions can be challenging. Intraoperative neurophysiological monitoring (IONM) during awake craniotomies can help identify language-eloquent areas and minimize postoperative impairments. Preoperative language testing is performed to establish a baseline before intraoperative language testing. This involves subjecting patients to predetermined tasks in the operating room to evaluate their phonological, semantic, and syntactic capabilities. The current state and future directions of intraoperative language testing procedures are discussed in this paper. The most common intraoperative tasks are counting and picture naming. However, some experts recommend utilizing more nuanced tasks that involve regions affected by infrequently occurring tumor patterns. Low-frequency bipolar Penfield stimulation is optimal for language mapping. Exception cases are discussed where awake craniotomies are not feasible. When dealing with multilingual patients, the patient's age of learning and skill level can be accounted for in terms of making informed task choices and mapping techniques to avoid any damage to language areas.

Technical Aspects of Motor and Language Mapping in Glioma Patients.

Gliomas are infiltrative primary brain tumors that often invade functional cortical and subcortical regions, and they mandate individualized brain mapping strategies to avoid postoperative neurological deficits. It is well known that maximal safe resection significantly improves survival, while postoperative deficits minimize the benefits associated with aggressive resections and diminish patients' quality of life. Although non-invasive imaging tools serve as useful adjuncts, intraoperative stimulation mapping (ISM) is the gold standard for identifying functional cortical and subcortical regions and minimizing morbidity during these challenging resections. Current mapping methods rely on the use of low-frequency and high-frequency stimulation, delivered with monopolar or bipolar probes either directly to the cortical surface or to the subcortical white matter structures. Stimulation effects can be monitored through patient responses during awake mapping procedures and/or with motor-evoked and somatosensory-evoked potentials in patients who are asleep. Depending on the patient's preoperative status and tumor location and size, neurosurgeons may choose to employ these mapping methods during awake or asleep craniotomies, both of which have their own benefits and challenges. Regardless of which method is used, the goal of intraoperative stimulation is to identify areas of non-functional tissue that can be safely removed to facilitate an approach trajectory to the equator, or center, of the tumor. Recent technological advances have improved ISM's utility in identifying subcortical structures and minimized the seizure risk associated with cortical stimulation. In this review, we summarize the salient technical aspects of which neurosurgeons should be aware in order to implement intraoperative stimulation mapping effectively and safely during glioma surgery.

Presurgical Language Mapping: What Are We Testing?

Gliomas are brain tumors infiltrating healthy cortical and subcortical areas that may host cognitive functions, such as language. If these areas are damaged during surgery, the patient might develop word retrieval or articulation problems. For this reason, many glioma patients are operated on awake, while their language functions are tested. For this practice, quite simple tests are used, for example, picture naming. This paper describes the process and timeline of picture naming (noun retrieval) and shows the timeline and localization of the distinguished stages. This is relevant information for presurgical language testing with navigated Magnetic Stimulation (nTMS). This novel technique allows us to identify cortical involved in the language production process and, thus, guides the neurosurgeon in how to approach and remove the tumor. We argue that not only nouns, but also verbs should be tested, since sentences are built around verbs, and sentences are what we use in daily life. This approach's relevance is illustrated by two case studies of glioma patients.

Intra- and inter-hemispheric network dynamics supporting object recognition and speech production.

We built normative brain atlases that animate millisecond-scale intra- and inter-hemispheric white matter-level connectivity dynamics supporting object recognition and speech production. We quantified electrocorticographic modulations during three naming tasks using event-related high-gamma activity from 1,114 nonepileptogenic intracranial electrodes (i.e., non-lesional areas unaffected by epileptiform discharges). Using this electrocorticography data, we visualized functional connectivity modulations defined as significant naming-related high-gamma modulations occurring simultaneously at two sites connected by direct white matter streamlines on diffusion-weighted imaging tractography. Immediately after stimulus onset, intra- and inter-hemispheric functional connectivity enhancements were confined mainly across modality-specific perceptual regions. During response preparation, left intra-hemispheric connectivity enhancements propagated in a posterior-to-anterior direction, involving the left precentral and prefrontal areas. After overt response onset, inter- and intra-hemispheric connectivity enhancements mainly encompassed precentral, postcentral, and superior-temporal (STG) gyri. We found task-specific connectivity enhancements during response preparation as follows. Picture naming enhanced activity along the left arcuate fasciculus between the inferior-temporal and precentral/posterior inferior-frontal (pIFG) gyri. Nonspeech environmental sound naming augmented functional connectivity via the left inferior longitudinal and fronto-occipital fasciculi between the medial-occipital and STG/pIFG. Auditory descriptive naming task enhanced usage of the left frontal U-fibers, involving the middle-frontal gyrus. Taken together, the commonly observed network enhancements include inter-hemispheric connectivity optimizing perceptual processing exerted in each hemisphere, left intra-hemispheric connectivity supporting semantic and lexical processing, and inter-hemispheric connectivity for symmetric oral movements during overt speech. Our atlases improve the currently available models of object recognition and speech production by adding neural dynamics via direct intra- and inter-hemispheric white matter tracts.