Intraoperative Language Mapping Research Articles

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

ObjectiveStimulation-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. MethodDifferentiation-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). ResultsIn 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. ConclusionsPreexisting 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.

Awake Craniotomy Language Mapping in Children With Drug-Resistant Epilepsy due to Focal Cortical Dysplasia

BackgroundLanguage mapping during awake craniotomy can allow for precise resection of epileptogenic lesions, while reducing the risk of damage to eloquent cortex. There are few reports in the literature of language mapping during awake craniotomy in children with epilepsy. Some centers may avoid awake craniotomy in the pediatric age group due to concerns that children are unable to cooperate with such procedures. MethodsWe reviewed pediatric patients from our center with drug-resistant focal epilepsy who underwent language mapping during awake craniotomy and subsequent resection of the epileptogenic lesion. ResultsTwo patients were identified, both female, aged 17 years and 11 years at the time of surgery. Both patients had frequent and disabling focal seizures despite trials of multiple antiseizure medications. Both patients had resection of their epileptogenic lesions with the aid of intraoperative language mapping; in both cases pathology was consistent with focal cortical dysplasia. Both patients had transient language difficulties in the immediate postoperative period but no deficits at six-month follow-up. Both patients are now seizure-free. ConclusionsAwake craniotomy should be considered in pediatric patients with drug-resistant epilepsy in whom the suspected epileptogenic lesion is in close proximity to cortical language areas.

Functional Magnetic Resonance Imaging and Diffusion Tensor Imaging for Language Mapping in Brain Tumor Surgery: Validation With Direct Cortical Stimulation and Cortico-Cortical Evoked Potential.

Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging-derived tractography (DTI-t) contribute to the localization of language areas, but their accuracy remains controversial. This study aimed to investigate the diagnostic performance of preoperative fMRI and DTI-t obtained with a simultaneous multi-slice technique using intraoperative direct cortical stimulation (DCS) or corticocortical evoked potential (CCEP) as reference standards. This prospective study included 26 patients (23-74 years; male:female, 13:13) with tumors in the vicinity of Broca's area who underwent preoperative fMRI and DTI-t. A site-by-site comparison between preoperative (fMRI and DTI-t) and intraoperative language mapping (DCS or CCEP) was performed for 226 cortical sites to calculate the sensitivity and specificity of fMRI and DTI-t for mapping Broca's areas. For sites with positive signals on fMRI or DTI-t, the true-positive rate (TPR) was calculated based on the concordance and discordance between fMRI and DTI-t. Among 226 cortical sites, DCS was performed in 100 sites and CCEP was performed in 166 sites. The specificities of fMRI and DTI-t ranged from 72.4% (63/87) to 96.8% (122/126), respectively. The sensitivities of fMRI (except for verb generation) and DTI-t were 69.2% (9/13) to 92.3% (12/13) with DCS as the reference standard, and 40.0% (16/40) or lower with CCEP as the reference standard. For sites with preoperative fMRI or DTI-t positivity (n = 82), the TPR was high when fMRI and DTI-t were concordant (81.2% and 100% using DCS and CCEP, respectively, as the reference standards) and low when fMRI and DTI-t were discordant (≤ 24.2%). fMRI and DTI-t are sensitive and specific for mapping Broca's area compared with DCS and specific but insensitive compared with CCEP. A site with a positive signal on both fMRI and DTI-t represents a high probability of being an essential language area.

NCOG-14. INTRAOPERATIVE COGNITIVE-LINGUISTIC MAPPING GUIDED BY VISUALIZATION OF GAMMA BAND MODULATION ELECTROCORTICOGRAMS: PROOF OF CONCEPT IN A PATIENT WITH LEFT TEMPORAL AND OCCIPITAL LOW-GRADE ASTROCYTOMA

Abstract OBJECTIVE Determine the feasibility and preliminary utility of a novel approach to intraoperative brain mapping guided by visualization of electrocorticography (ECoG) heat maps. METHODS A 39-year-old male with a biopsy-proven left posterior temporal and occipital WHO grade II IDH-mutant astrocytoma underwent awake craniotomy with intraoperative language mapping. Language mapping utilized a dual iPad stimulus presentation system (NeuroMapper) coupled to a portable real-time neural signal processing system capable of both recording cortical activity and delivering direct cortical stimulation in a closed-loop fashion. An ECoG grid (4x8 with 1cm pitch) which covered the majority of the left temporal lobe was used to assess oscillatory cortical activity during administration of language paradigms including object, action, auditory descriptive, and written descriptive naming. ECoG recording and cortical stimulation were synchronized with stimulus presentation via a photosensor attached to the patient-facing tablet. Gamma band modulations in response to language paradigms at each electrode were processed in real-time and visualized as heat maps in MATLAB/Simulink. Following recording and visualization, bipolar direct cortical stimulation from the grid was conducted for each neighboring electrode pair (up to an intensity of 6 mA) during administration of language tasks. RESULTS Despite mild fluent aphasia, a large set of reliable baseline stimuli were obtained for the language mapping paradigms. All naming paradigms resulted in strongest heat map activation at electrode 12 located in the anterior to mid superior temporal gyrus. During stimulation, consistent speech arrest was observed across all paradigms when stimulating electrode pair 11-12, indicating good correspondence with ECoG heat map recordings. Additionally, this region corresponded well with posterior language network representation via resting-state fMRI. CONCLUSION Intraoperative real-time visualization of task-based ECoG gamma band modulation is feasible and may help identify targets for direct cortical stimulation. If validated, this may improve the efficiency and accuracy of intraoperative language mapping.

Preoperative Navigated Transcranial Magnetic Stimulation: New Insight for Brain Tumor-Related Language Mapping.

Preoperative brain mapping methods are particularly important in modern neuro-oncology when a tumor affects eloquent language areas since damage to parts of the language circuits can cause significant impairments in daily life. This narrative review examines the literature regarding preoperative and intraoperative language mapping using repetitive navigated transcranial magnetic stimulation (rnTMS) with or without direct electrical stimulation (DES) in adult patients with tumors in eloquent language areas. The literature shows that rnTMS is accurate in detecting preexisting language disorders and positive intraoperative mapping regions. In terms of the region extent and clinical outcomes, rnTMS has been shown to be accurate in identifying positive sites to guide resection, reducing surgery duration and craniotomy size and thus improving clinical outcomes. Before incorporating rnTMS into the neurosurgical workflow, the refinement of protocols and a consensus within the neuro-oncology community are required.

Evaluating the concordance of functional MRI-based language lateralization and Wada testing in epilepsy patients: A single-center analysis.

For patients with drug-resistant epilepsy, surgery may be effective in controlling their disease. Surgical evaluation may involve localization of the language areas using functional magnetic resonance imaging (fMRI) or Wada testing. We evaluated the accuracy of task-based fMRI versus Wada-based language lateralization in a cohort of our epilepsy patients. In a single-center, retrospective analysis, we identified patients with medically intractable epilepsy who participated in presurgical language mapping (n = 35) with fMRI and Wada testing. Demographic variables and imaging metrics were obtained. We calculated the laterality index (LI) from task-evoked fMRI activation maps across language areas during auditory and reading tasks to determine lateralization. Possible scores for LI range from -1 (strongly left-hemisphere dominant) to 1 (strongly right-hemisphere dominant). Concordance between fMRI and Wada was estimated using Cohen's Kappa coefficient. Association between the LI scores from the auditory and reading tasks was tested using Spearman's rank correlation coefficient. The fMRI-based laterality indices were concordant with results from Wada testing in 91.4% of patients during the reading task (κ = .55) and 96.9% of patients during the auditory task (κ = .79). The mean LIs for the reading and auditory tasks were -0.52 ± 0.43 and -0.68 ± 0.42, respectively. The LI scores for the language and reading tasks were strongly correlated, r(30) = 0.57 (p = 0.001). Our findings suggest that fMRI is generally an accurate, low-risk alternative to Wada testing for language lateralization. However, when fMRI indicates atypical language lateralization (e.g., bilateral dominance), patients may benefit from subsequent Wada testing or intraoperative language mapping.

Awake brain surgery for language mapping in pediatric patients: a single-center experience.

The goal of this study was to evaluate the feasibility, benefit, and safety of awake brain surgery (ABS) and intraoperative language mapping in children and adolescents with structural epilepsies. Whereas ABS is an established method to monitor language function in adults intraoperatively, reports of ABS in children are scarce. A retrospective chart review of pediatric patients ≤ 18 years of age who underwent ABS and cortical language mapping for supratentorial tumors and nontumoral epileptogenic lesions between 2008 and 2019 was conducted. The authors evaluated the global intellectual and specific language performance by using detailed neuropsychological testing, the patient's intraoperative compliance, results of intraoperative language mapping assisted by electrocorticography (ECoG), and postsurgical language development and seizure outcomes. Descriptive statistics were used for this study, with a statistical significance of p < 0.05. Eleven children (7 boys) with a median age of 13 years (range 10-18 years) underwent ABS for a lesion in close vicinity to cortical language areas as defined by structural and functional MRI (left hemisphere in 9 children, right hemisphere in 2). Patients were neurologically intact but experiencing seizures; these were refractory to therapy in 9 patients. Compliance during the awake phase was high in 10 patients and low in 1 patient. Cortical mapping identified eloquent language areas in 6/10 (60%) patients and was concordant in 3/8 (37.5%), discordant in 3/8 (37.5%), and unclear in 2/8 (25%) patients compared to preoperative functional MRI. Stimulation-induced seizures occurred in 2 patients and could be interrupted easily. ECoG revealed that afterdischarge potentials (ADP) were involved in 5/9 (56%) patients with speech disturbances during stimulation. None of these patients harbored postoperative language dysfunction. Gross-total resection was achieved in 10/11 (91%) patients, and all were seizure free after a median follow-up of 4.3 years. Neuropsychological testing using the Wechsler Intelligence Scale for Children and the verbal learning and memory test showed an overall nonsignificant trend toward an immediate postoperative deterioration followed by an improvement to above preoperative levels after 1 year. ABS is a valuable technique in selected pediatric patients with lesions in language areas. An interdisciplinary approach, careful patient selection, extensive preoperative training of patients, and interpretation of intraoperative ADP are pivotal to a successful surgery.

Validation of Non-invasive Language Mapping Modalities for Eloquent Tumor Resection: A Pilot Study.

Many studies have established a link between extent of resection and survival in patients with gliomas. Surgeons must optimize the oncofunctional balance by maximizing the extent of resection and minimizing postoperative neurological morbidity. Preoperative functional imaging modalities are important tools for optimizing the oncofunctional balance. Transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) are non-invasive imaging modalities that can be used for preoperative functional language mapping. Scarce data exist evaluating the accuracy of these preoperative modalities for language mapping compared with gold standard intraoperative data in the same cohort. This study compares the accuracy of fMRI and TMS for language mapping compared with intraoperative direct cortical stimulation (DCS). We also identified significant predictors of preoperative functional imaging accuracy, as well as significant predictors of functional outcomes. Evidence from this study could inform clinical judgment as well as provide neuroscientific insight. We used geometric distances to determine copositivity between preoperative data and intraoperative data. Twenty-eight patients were included who underwent both preoperative fMRI and TMS procedures, as well as an awake craniotomy and intraoperative language mapping. We found that TMS shows significantly superior correlation to intraoperative DCS compared with fMRI. TMS also showed significantly higher sensitivity and negative predictive value than specificity and positive predictive value. Poor cognitive baseline was associated with decreased TMS accuracy as well as increased risk for worsened aphasia postoperatively. TMS has emerged as a promising preoperative language mapping tool. Future work should be done to identify the proper role of each imaging modality in a comprehensive, multimodal approach to optimize the oncofunctional balance.

Two different subcortical language networks supporting distinct Japanese orthographies: morphograms and phonograms.

Language systems worldwide are based on either morphograms or phonograms, but Japanese is unique in that uses a complicated combination of kanji (morphogram) and kana (phonogram) characters. The white matter networks associated with reading have been investigated previously but remain incompletely understood. In this study, we performed intraoperative language mapping under local anesthesia and postoperative language assessments of 53 consecutive patients who underwent awake craniotomy for surgical resection of cerebral glioma within the dominant temporal or parietal lobe. Six cases showing intraoperative dyslexia elicited by direct electrical stimulation (DES) were examined, and all cases showed transient symptoms of kanji or kana dyslexia during DES. We investigated the intraoperative positive mapping points localized near four white matter bundles: the arcuate fascicle, posterior superior longitudinal fascicle, inferior fronto-occipital longitudinal fascicle, and inferior longitudinal fascicle (ILF). The intraoperative DES distributions for kanji dyslexia were especially associated with the anterior-inferior side of the ILF. On the other hand, the DES points associated with kana dyslexia were localized on the posterior-superior side of the complex composed of these four tracts. These results suggest the presence of specific non-interfering networks that subserve the processes of reading morphograms and phonograms.

A Data-Based Approach for Selecting Pre- and Intra-Operative Language Mapping Tasks.

Background: Pre- and intra-operative language mapping in neurosurgery patients frequently involves an object naming task. The choice of the optimal object naming paradigm remains challenging due to lack of normative data and standardization in mapping practices. The aim of this study was to identify object naming paradigms that robustly and consistently activate classical language regions and could therefore be used to improve the sensitivity of language mapping in brain tumor and epilepsy patients.Methods: Functional magnetic resonance imaging (fMRI) data from two independent groups of healthy controls (total = 79) were used to generate threshold-weighted voxel-based consistency maps. This novel approach allowed us to compare inter-subject consistency of activation for naming single objects in the visual and auditory modality and naming two objects in a phrase or a sentence.Results: We found that the consistency of activation in language regions was greater for naming two objects per picture than one object per picture, even when controlling for the number of names produced in 5 s.Conclusion: More consistent activation in language areas for naming two objects compared to one object suggests that two-object naming tasks may be more suitable for delimiting language eloquent regions with pre- and intra-operative language testing. More broadly, we propose that the functional specificity of brain mapping paradigms for a whole range of different linguistic and non-linguistic functions could be enhanced by referring to databased models of inter-subject consistency and variability in typical and atypical brain responses.

BRMP-01. Awake cranial surgery with intraoperative language mapping for brain tumors. A single-center experience

Abstract BACKGROUND Maximal safe resection of brain tumors affecting language areas has been a matter of increasing interest worldwide in the last decades. Functional MRI, tractography, and awake cranial surgery are standard procedures in our department since 2006. The aim of this study was to describe our experience in a series of 58 patients who underwent awake cranial surgery with intraoperative language mapping. METHODS Retrospective study of 58 adult patients who underwent awake surgery for brain tumors between January 2006 and January 2021. Preoperative neuropsychological assessment served as inclusion criteria. Language was evaluated according to the BDAE (Boston diagnostic aphasia examination) and WAB (Western aphasia battery) and strength according to the MRC (Medical Research Council) motor scale in the preoperative, immediate postoperative, and 3-months follow up. Functional MRI and tractography depicting white-matter tracts, neuronavigation, cortical and subcortical stimulation were performed in all cases. Conscious sedation was the anesthetic technique (propofol, fentanyl, and NSAIDs). Minimum follow-up was 6 months. FINDINGS The average age was 35 years (16–74). The anatomopathological findings were: low-grade glioma in 75,8% (n = 44), high-grade glioma in 15,6% (n = 9) and others in 8,6% (n = 5). No complications were registered during postoperative course. At the immediate postoperative evaluation 65% of patients presented with speech disturbances but at the 3-months follow up speech recovery was observed in all cases. Only 1 patient remained with moderate aphasia. mRS score at 3- months follow up was ≤ 1 in 96% of patients. Two patients had a persistent moderate hemiparesis. CONCLUSION Tumor resection in awake patients showed to be a safe procedure, and well tolerated by the patients. Preoperative planning of anatomical and functional aspects and intraoperative neurophysiological assessment are the cornerstones for pursuing maximal safe resection.

Advancing Neurolinguistics in Russia: Experience and Implications of Building Experimental Research and Evidence-Based Practices.

Russia has rich theoretical and behavioral research traditions in neurolinguistics and neuropsychology, but at the beginning of the twenty-first century contemporary experimental research in these disciplines remained limited, leading to proliferation of non-evidence-based approaches in education, healthcare, and public beliefs. An academic response to this was the establishment of the Center for Language and Brain at the HSE University, Moscow, which focused on experimental psycho- and neurolinguistic research and related evidence-based practices. The Center has grown from a small group of young researchers to a large interdisciplinary unit that conducts cutting-edge research utilizing multi-site settings and novel structural and functional neuroimaging methods. The overarching aim of the Center's research is to promote scientifically grounded treatment of the language-brain relationship in the educational, clinical, and industry settings. Specifically, translational research at the Center is contributing to the advancement of clinical practice in Russia: from providing the first standardized aphasia language test to implementing protocols for intraoperative language mapping in neurosurgery departments across the country. Within research projects, a new generation of scientists is successfully being fostered, while a broader student audience is reached via courses taught by staff of the Center to students of different majors. Notable examples of public outreach programs at the Center are the Annual Summer Neurolinguistics School attracting hundreds of attendees from different countries each year, and community projects focused on raising awareness about aphasia. Together, these efforts aim to increase scientific knowledge in a multi-professional audience. In this paper, we will share our joint experiences in establishing, building, and promoting a neurolinguistics research center in Russia and the impact that this work has had on the broader public. We will delineate specific milestones of this journey and focus on the main pillars that have contributed to our progress: research, clinical work, teaching, and public outreach programs. We hope that this critical appraisal of our experiences can serve simultaneously as an inspiration and a practical guide for other groups developing research, clinical, and educational programs in different neuroscientific disciplines across the globe and aiming to improve the quality of the neuroscientific information available to the public.

What Can Glioma Patients Teach Us about Language (Re)Organization in the Bilingual Brain: Evidence from fMRI and MEG.

Simple SummaryLow-grade glioma (LGG) patients constitute an ideal in vivo pathological model to investigate cerebral neuroplasticity associated with major architectural disruption to the language network. Bilingual LGG patients offer a unique opportunity to study the neural capacity to negotiate L1 and L2 processing before and after the resection of critical language hubs. By combining the spatial resolution of fMRI with the temporal resolution and oscillatory information provided by MEG, we mapped the language network and its functional (re)organization in five Spanish–Basque bilingual patients. Both techniques provide converging evidence that different reshaping patterns occur for L1 and L2 after tumor resection. These changes affect not only language-specific nodes, but also areas associated with executive control mechanisms, underscoring the need for multilingual intraoperative approaches. Understanding neural (re)organization in the bilingual brain is crucial for preserving language function by means of personalized surgical interventions and rehabilitation strategies based on the patient’s linguistic profile.Recent evidence suggests that the presence of brain tumors (e.g., low-grade gliomas) triggers language reorganization. Neuroplasticity mechanisms called into play can transfer linguistic functions from damaged to healthy areas unaffected by the tumor. This phenomenon has been reported in monolingual patients, but much less is known about the neuroplasticity of language in the bilingual brain. A central question is whether processing a first or second language involves the same or different cortical territories and whether damage results in diverse recovery patterns depending on the language involved. This question becomes critical for preserving language areas in bilingual brain-tumor patients to prevent involuntary pathological symptoms following resection. While most studies have focused on intraoperative mapping, here, we go further, reporting clinical cases for five bilingual patients tested before and after tumor resection, using a novel multimethod approach merging neuroimaging information from fMRI and MEG to map the longitudinal reshaping of the language system. Here, we present four main findings. First, all patients preserved linguistic function in both languages after surgery, suggesting that the surgical intervention with intraoperative language mapping was successful in preserving cortical and subcortical structures necessary for brain plasticity at the functional level. Second, we found reorganization of the language network after tumor resection in both languages, mainly reflected by a shift of activity to right hemisphere nodes and the recruitment of ipsilesional left nodes. Third, we found that this reorganization varied according to the language involved, indicating that L1 and L2 follow different reshaping patterns after surgery. Fourth, oscillatory longitudinal effects were correlated with BOLD laterality changes in superior parietal and middle frontal areas. These findings may reflect that neuroplasticity impacts on the compensatory involvement of executive control regions, supporting the allocation of cognitive resources as a consequence of increased attentional demands. Furthermore, these results hint at the complementary role of this neuroimaging approach in language mapping, with fMRI offering excellent spatial localization and MEG providing optimal spectrotemporal resolution.

Language Mapping Using Stereo Electroencephalography: A Review and Expert Opinion.

Stereo-electroencephalography (sEEG) is a method that uses stereotactically implanted depth electrodes for extra-operative mapping of epileptogenic and functional networks. sEEG derived functional mapping is achieved using electrical cortical stimulations (ECS) that are currently the gold standard for delineating eloquent cortex. As this stands true especially for primary cortices (e.g., visual, sensitive, motor, etc.), ECS applied to higher order brain areas determine more subtle behavioral responses. While anterior and posterior language areas in the dorsal language stream seem to share characteristics with primary cortices, basal temporal language area (BTLA) in the ventral temporal cortex (VTC) behaves as a highly associative cortex. After a short introduction and considerations about methodological aspects of ECS using sEEG, we review the sEEG language mapping literature in this perspective. We first establish the validity of this technique to map indispensable language cortices in the dorsal language stream. Second, we highlight the contrast between the growing empirical ECS experience and the lack of understanding regarding the fundamental mechanisms underlying ECS behavioral effects, especially concerning the dispensable language cortex in the VTC. Evidences for considering network architecture as determinant for ECS behavioral response complexities are discussed. Further, we address the importance of designing new research in network organization of language as this could enhance ECS ability to map interindividual variability, pathology driven reorganization, and ultimately identify network resilience markers in order to better predict post-operative language deficit. Finally, based on a whole body of available studies, we believe there is strong evidence to consider sEEG as a valid, safe and reliable method for defining eloquent language cortices although there have been no proper comparisons between surgical resections with or without extra-operative or intra-operative language mapping.

A Novel Language Paradigm for Intraoperative Language Mapping: Feasibility and Evaluation.

(1) Background—Mapping language using direct cortical stimulation (DCS) during an awake craniotomy is difficult without using more than one language paradigm that particularly follows the demand of DCS by not exceeding the assessment time of 4 s to prevent intraoperative complications. We designed an intraoperative language paradigm by combining classical picture naming and verb generation, which safely engaged highly relevant language functions. (2) Methods—An evaluation study investigated whether a single trial of the language task could be performed in less than 4 s in 30 healthy subjects and whether the suggested language paradigm sufficiently pictured the cortical language network using functional magnetic resonance imaging (fMRI) in 12 healthy subjects. In a feasibility study, 24 brain tumor patients conducted the language task during an awake craniotomy. The patients’ neuropsychological outcomes were monitored before and after surgery. (3) Results—The fMRI results in healthy subjects showed activations in a language-associated network around the (left) sylvian fissure. Single language trials could be performed within 4 s. Intraoperatively, all tumor patients showed DCS-induced language errors while conducting the novel language task. Postoperatively, mild neuropsychological impairments appeared compared to the presurgical assessment. (4) Conclusions—These data support the use of a novel language paradigm that safely monitors highly relevant language functions intraoperatively, which can consequently minimize negative postoperative neuropsychological outcomes.

Linguistic Specificity of the Left Temporal Cortex: Intraoperative Brain Mapping Data

The present study sought to test the hypothesis that the production of speech and the comprehension of speech in the left temporal lobe can be anatomically disassociated. Moreover, it is aimed to show that the standard intraoperative object naming task is not sufficient to test all the functionally essential areas in the left temporal lobe. In the introductory part of the article we described the existing information about the left temporal lobe and the awake surgery procedure. In the course of the study, we collected and analyzed the data from intraoperative brain mapping of 25 patients with brain lesions – gliomas or pharmacoresistant epilepsy, who underwent awake craniotomy. All the patient went through intraoperative language mapping with the use of direct electrical stimulation. In order to map language production and comprehension modalities, in addition to the classical object naming task we used an additional task, the phonological judgment task. The results showed substantial dissociation between mapping of two tasks. According to these findings, we can conclude that the object naming task alone is not suitable for adequate brain mapping of the left temporal cortex. The same dissociation may be regarded as an argument in favor of the anatomical dissociation of the production and comprehension of speech in the left temporal cortex.

Functional linguistic specificity of the left frontal aslant tract for spontaneous speech fluency: Evidence from intraoperative language mapping

The left frontal aslant tract (FAT) has been proposed to be relevant for language, and specifically for spontaneous speech fluency. However, there is missing causal evidence that stimulation of the FAT affects spontaneous speech, and not language production in general. We present a series of 12 neurosurgical cases with awake language mapping of the cortex near the left FAT. Tasks for language mapping included the commonly used action picture naming, and sentence completion, tapping more specifically into spontaneous speech. A task dissociation was found in 10 participants: while being stimulated on specific sites, they were able to name a picture but could not complete a sentence. Overlaying of these sites on preoperative white-matter tract reconstructions revealed that in each individual case they were located on cortical terminations of the FAT. This corroborates the language functional specificity of the left FAT as a tract underlying fluent spontaneous speech.

Impact of Priming on Effectiveness of TMS in Detecting Language-eloquent Brain Areas in Tumor Patients.

Language is characteristically human, and preserving it is critical when resecting tumors in language-eloquent brain areas. Navigated repetitive transcranial magnetic stimulation (nrTMS) has been used in recent years as a noninvasive technique to identify preoperatively the language-eloquent cortical areas in tumor patients. An important objective is to increase the sensitivity and specificity of nrTMS in detecting language-related areas and increase the positive correlation of its results to that of intraoperative direct cortical stimulation (DCS). Although the technical aspects of the procedure have received enormous interest, factors related to the targeted cortical area such as previous cortical history or activity have been neglected. Therefore, the present study explores the impact of previous cortical history or activity on the effectiveness of a subsequent nrTMS mapping paradigm. Twelve right-handed patients with a left hemispheric glioma underwent presurgical nrTMS language mapping and intraoperative language mapping with DCS. nrTMS was performed using a continuous theta burst stimulation paradigm to inhibit possible language relevant areas in the vicinity of the tumor, determined anatomically or based on functional magnetic resonance imaging hotspots. The nrTMS was applied in two separate sessions. One of the sessions randomly included a priming paradigm to precondition the targeted cortical areas. Priming stimulation decreased the error detection of the subsequent nrTMS mapping paradigm. This effect was more robust on major types of errors such as speech arrest and hesitation. Prior cortical activity as induced by the priming stimulation has a profound impact on the responsiveness to the nrTMS mapping paradigm. Our findings further showed that metaplasticity, a type of homeostatic plastic process, could be elicited even in cortical areas affected by a growing tumor.

The verb and noun test for peri-operative testing (VAN-POP): standardized language tests for navigated transcranial magnetic stimulation and direct electrical stimulation

BackgroundProtocols for intraoperative language mapping with direct electrical stimulation (DES) often include various language tasks triggering both nouns and verbs in sentences. Such protocols are not readily available for navigated transcranial magnetic stimulation (nTMS), where only single word object naming is generally used. Here, we present the development, norming, and standardization of the verb and noun test for peri-operative testing (VAN-POP) that measures language skills more extensively.MethodsThe VAN-POP tests noun and verb retrieval in sentence context. Items are marked and balanced for several linguistic factors known to influence word retrieval. The VAN-POP was administered in English, German, and Dutch under conditions that are used for nTMS and DES paradigms. For each language, 30 speakers were tested.ResultsAt least 50 items per task per language were named fluently and reached a high naming agreement.ConclusionThe protocol proved to be suitable for pre- and intraoperative language mapping with nTMS and DES.

SURG-19. REORGANIZATION OF LANGUAGE ENABLES SAFE RESECTION OF TUMORS IN AND AROUND BROCA’S AREA

Abstract INTRODUCTION Since its discovery in the 1800s, Broca’s area has been viewed as a critical node for language production. Previously, pathologies in this area have been considered unresectable due to concern for producing iatrogenic language production deficits. Emerging literature suggests that although acute lesions in this area can cause widespread deficits, slow growing lesions are less correlated with these deficits due to cortical language reorganization. Based on this data, we managed a cohort with Broca’s area lesions with surgical resection using awake intra-operative language mapping. METHODS All 150 awake craniotomies performed by the senior author over a twelve-year period (2006–2017) at a single institution were reviewed. For each patient the imaging was carefully evaluated to localize the neoplasm relative to pars triangularis or pars opercularis in the language dominant hemisphere. Language dominance was confirmed using WADA testing or fMRI. All patients underwent cortical language mapping using a battery of tasks coupled with cortical stimulation. RESULTS A total of 31 surgeries in 29 patients (65.5% male, 86.2% righthanded) were identified. The average age was 41. Patients presented with seizures (64.5%), speech difficulties (35.5%) or headaches (19.4%). A gross or near total resection was achieved in 26/29 (89.7%) of patients. Pathological evaluation revealed grade 2 gliomas (8), grade 3 gliomas (13) and glioblastoma (9). Post-operatively, 8 (25.8%) patients had new or worsening speech deficits, all of which resolved to baseline at follow-up. CONCLUSION Broca’s area lesions can be safely resected in patients using an awake craniotomy technique with language mapping. In our series, the majority of patients had gross or near total resections, few patients had new deficits, and none had permanent new deficits. Considering the increasing evidence in favor of cytoreduction to manage glial neoplasms, this technique should be employed routinely for pathologies in this area to optimize patient outcomes.