Awake craniotomy to maximize glioma resection: methods and technical nuances over a 27-year period

Surgical Treatment of Glioblastoma: State-of-the-Art and Future Trends

Glioblastoma (GBM) is a highly aggressive disease and is associated with poor prognosis despite treatment advances in recent years. Surgical resection of tumor remains the main therapeutic option when approaching these patients, especially when combined with adjuvant radiochemotherapy. In the present study, we conducted a comprehensive literature review on the state-of-the-art and future trends of the surgical treatment of GBM, emphasizing topics that have been the object of recent study.

Advanced frailty assessment tool predicts successful awake craniotomy in a 92-year-old patient: A case report

Background:

The awake craniotomy (AC) procedure allows for safe and maximal resection of brain tumors from highly eloquent regions. However, geriatric patients are often viewed as poor candidates for AC due to age and medical comorbidities. Frailty assessments gauge physiological reserve for surgery and are valuable tools for preoperative decision-making. Here, we present a novel case illustrating how frailty scoring enabled an elderly but otherwise healthy female to undergo successful AC for tumor resection.

Case Description:

A 92-year-old right-handed female with history of hypertension and basal cell skin cancer presented with a 1-month history of progressive aphasia and was found to have a ring-enhancing left frontoparietal mass abutting the rolandic cortex concerning for malignant neoplasm. Frailty scoring with the recalibrated risk analysis index (RAI-C) tool revealed a score of 30 (of 81) indicating low surgical risk. The patient and family were counseled appropriately that, despite advanced chronological age, a low frailty score predicts favorable surgical outcomes. The patient underwent left-sided AC for resection of tumor and experienced immediate improvement of speech intraoperatively. After surgery, the patient was neurologically intact and had an unremarkable postoperative course with significant improvements from preoperatively baseline at follow-up.

Conclusion:

To the best of our knowledge, this case represents the oldest patient to undergo successful AC for brain tumor resection. Nonfrail patients over 90 years of age with the proper indications may tolerate cranial surgery. Frailty scoring is a powerful tool for preoperative risk assessment in the geriatric neurosurgery population.

Simultaneous Motor and Visual Intraoperative Neuromonitoring in Asleep Parietal Lobe Surgery: Dual Strip Technique

Background: The role played by the non-dominant parietal lobe in motor cognition, attention and spatial awareness networks has potentiated the use of awake surgery. When this is not feasible, asleep monitoring and mapping techniques should be used to achieve an onco-functional balance. Objective: This study aims to assess the feasibility of a dual-strip method to obtain direct cortical stimulation for continuous real-time cortical monitoring and subcortical mapping of motor and visual pathways simultaneously in parietal lobe tumour surgery. Methods: Single-centre prospective study between 19 May−20 November of patients with intrinsic non-dominant parietal-lobe tumours. Two subdural strips were used to simultaneously map and monitor motor and visual pathways. Results: Fifteen patients were included. With regards to motor function, a large proportion of patients had abnormal interhemispheric resting motor threshold ratio (iRMTr) (71.4%), abnormal Cortical Excitability Score (CES) (85.7%), close distance to the corticospinal tract—Lesion-To-Tract Distance (LTD)—4.2 mm, Cavity-To-Tract Distance (CTD)—7 mm and intraoperative subcortical distance—6.4 mm. Concerning visual function, the LTD and CTD for optic radiations (OR) were 0.5 mm and 3.4 mm, respectively; the mean intensity for positive subcortical stimulation of OR was 12 mA ± 2.3 mA and 5/6 patients with deterioration of VEPs > 50% had persistent hemianopia and transgression of ORs. Twelve patients remained stable, one patient had a de-novo transitory hemiparesis, and two showed improvements in motor symptoms. A higher iRMTr for lower limbs was related with a worse motor outcome (p = 0.013) and a longer CTD to OR was directly related with a better visual outcome (p = 0.041). At 2 weeks after hospital discharge, all patients were ambulatory at home, and all proceeded to have oncological treatment. Conclusion: We propose motor and visual function boundaries for asleep surgery of intrinsic non-dominant parietal tumours. Pre-operative abnormal cortical excitability of the motor cortex, deterioration of the VEP recordings and CTD < 2 mm from the OR were related to poorer outcomes.

Propofol enhances stem-like properties of glioma via GABAAR-dependent Src modulation of ZDHHC5-EZH2 palmitoylation mechanism

Background

Propofol is a commonly used anesthetic. However, its effects on glioma growth and recurrence remain largely unknown.

Methods

The effect of propofol on glioma growth was demonstrated by a series of in vitro and in vivo experiments (spheroidal formation assay, western blotting, and xenograft model). The acyl-biotin exchange method and liquid chromatography-mass spectrometry assays identified palmitoylation proteins mediated by the domain containing the Asp-His-His-Cys family. Western blotting, co-immunoprecipitation, quantitative real-time polymerase chain reaction, co-immunoprecipitation, chromatin immunoprecipitation, and luciferase reporter assays were used to explore the mechanisms of the γ-aminobutyric acid receptor (GABA_AR)/Src/ZDHHC5/EZH2 signaling axis in the effects of propofol on glioma stem cells (GSCs).

Results

We found that treatment with a standard dose of propofol promoted glioma growth in nude mice compared with control or low-dose propofol. Propofol-treated GSCs also led to larger tumor growth in nude mice than did vector-treated tumors. Mechanistically, propofol enhances the stem-like properties of gliomas through GABA_AR to increase Src expression, thereby enhancing the palmitoylation of ZDHHC5-mediated EZH2 and Oct4 expression.

Conclusion

These results demonstrate that propofol may promote glioma growth through the GABA_AR-Src-ZDHHC5-EZH2 mechanism and are helpful in guiding the clinical use of propofol to obtain a better patient prognosis after the surgical resection of tumors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03087-5.

Patient-reported intraoperative experiences during awake craniotomy for brain tumors: a scoping review

Awake craniotomy (AC) is a neurosurgical procedure that may be used to excise tumors located in eloquent areas of the brain. The techniques and outcomes of AC have been extensively described, but data on patient-reported experiences are not as well known. To determine these, we performed a scoping review of patient-reported intraoperative experiences during awake craniotomy for brain tumor resection. A total of 21 articles describing 534 patients were included in the review. Majority of the studies were performed on adult patients and utilized questionnaires and interviews. Some used additional qualitative methodology such as grounded theory and phenomenology. Most of the evaluation was performed within the first 2 weeks post-operatively. Recollection of the procedure ranged from 0 to 100%, and most memories dealt with the cranial fixation device application, cranial drilling, and intraoperative mapping. All patients reported some degree of pain and discomfort, mainly due to the cranial fixation device and uncomfortable operative position. Most patients were satisfied with their AC experience. They felt that participating in AC gave them a sense of control over their disease and thought that trust in the treatment team and adequate pre-operative preparation were very important. Patients who underwent AC for brain tumor resection had both positive and negative experiences intraoperatively, but overall, majority had a positive perception of and high levels of satisfaction with AC. Successful AC depends not only on a well-conducted intraoperative course, but also on adequate pre-operative information and patient preparation.

Involvement of White Matter Language Tracts in Glioma: Clinical Implications, Operative Management, and Functional Recovery After Injury

To achieve optimal survival and quality of life outcomes in patients with glioma, the extent of tumor resection must be maximized without causing injury to eloquent structures. Preservation of language function is of particular importance to patients and requires careful mapping to reveal the locations of cortical language hubs and their structural and functional connections. Within this language network, accurate mapping of eloquent white matter tracts is critical, given the high risk of permanent neurological impairment if they are injured during surgery. In this review, we start by describing the clinical implications of gliomas involving white matter language tracts. Next, we highlight the advantages and limitations of methods commonly used to identify these tracts during surgery including structural imaging techniques, functional imaging, non-invasive stimulation, and finally, awake craniotomy. We provide a rationale for combining these complementary techniques as part of a multimodal mapping paradigm to optimize postoperative language outcomes. Next, we review local and long-range adaptations that take place as the language network undergoes remodeling after tumor growth and surgical resection. We discuss the probable cellular mechanisms underlying this plasticity with emphasis on the white matter, which until recently was thought to have a limited role in adults. Finally, we provide an overview of emerging developments in targeting the glioma-neuronal network interface to achieve better disease control and promote recovery after injury.

Functional outcomes after resection of middle frontal gyrus diffuse gliomas

OBJECTIVE

The clinical outcomes for patients undergoing resection of diffuse glioma within the middle frontal gyrus (MFG) are understudied. Anatomically, the MFG is richly interconnected to known language areas, and nearby subcortical fibers are at risk during resection. The goal of this study was to determine the functional outcomes and intraoperative mapping results related to resection of MFG gliomas. Additionally, the study aimed to evaluate if subcortical tract disruption on imaging correlated with functional outcomes.

METHODS

The authors performed a retrospective review of 39 patients with WHO grade II-IV diffuse gliomas restricted to only the MFG and underlying subcortical region that were treated with resection and had no prior treatment. Intraoperative mapping results and postoperative neurological deficits by discharge and 90 days were assessed. Diffusion tensor imaging (DTI) tractography was used to assess subcortical tract integrity on pre- and postoperative imaging.

RESULTS

The mean age of the cohort was 37.9 years at surgery, and the median follow-up was 5.1 years. The mean extent of resection was 98.9% for the cohort. Of the 39 tumors, 24 were left sided (61.5%). Thirty-six patients (92.3%) underwent intraoperative mapping, with 59% of patients undergoing an awake craniotomy. No patients had positive cortical mapping sites overlying the tumor, and 12 patients (33.3%) had positive subcortical stimulation sites. By discharge, 8 patients had language dysfunction, and 5 patients had mild weakness. By 90 days, 2 patients (5.1%) had persistent mild hand weakness only. There were no persistent language deficits by 90 days. On univariate analysis, preoperative tumor size (p = 0.0001), positive subcortical mapping (p = 0.03), preoperative tumor invasion of neighboring subcortical tracts on DTI tractography (p = 0.0003), and resection cavity interruption of subcortical tracts on DTI tractography (p < 0.0001) were associated with an increased risk of having a postoperative deficit by discharge. There were no instances of complete subcortical tract transections in the cohort.

CONCLUSIONS

MFG diffuse gliomas may undergo extensive resection with minimal risk for long-term morbidity. Partial subcortical tract interruption may lead to transient but not permanent deficits. Subcortical mapping is essential to reduce permanent morbidity during resection of MFG tumors by avoiding complete transection of critical subcortical tracts.

Radiotherapy-drug combinations in the treatment of glioblastoma: a brief review

Glioblastoma (GBM) accounts for over 50% of gliomas and carries the worst prognosis of all solid tumors. Owing to the limited local control afforded by surgery alone, efficacious adjuvant treatments such as radiotherapy (RT) and chemotherapy are fundamental in achieving durable disease control. The best clinical outcomes are achieved with tri-modality treatment consisting of surgery, RT and systemic therapy. While RT-chemotherapy combination regimens are well established in oncology, this approach was largely unsuccessful in GBM until the introduction of temozolomide. The success of this combination has stimulated the search for other candidate drugs for concomitant use with RT in GBM. This review seeks to collate the current evidence for these agents and synthesize possible future directions for the field.

Temporal Trends in Glioblastoma Survival: Progress then Plateau

BACKGROUND

Survival of patients with glioblastoma (GBM) increased in the 2000s, most prominently after the addition of temozolomide to the standard-of-care treatment protocol. The reason for subsequent improvements in survival in the late 2000s and early 2010s was less clear, with explanations including the introduction of bevacizumab, better surgical methods, and advances in supportive care. It is uncertain whether the trend of improving population-level survival has continued.

MATERIALS AND METHODS

Data from the Surveillance, Epidemiology, and End Results (SEER) Program was analyzed comparing survival of adult GBM patients diagnosed in consecutive 3-year periods from 2000 to 2017. Kaplan-Meier survival analysis and Cox proportional hazards models were used.

RESULTS

A total of 38,352 patients diagnosed with GBM between 2000 and 2017 met inclusion criteria. Median survival and percent survival to 12 and 24 months all progressively increased between 2000 and 2011. There were no significant differences in survival comparing 2009-2011 with 2012-2014 or 2015-2017. During the 2015-2017 period, median survival was 11 months, with 12 and 24-month survival proportions of 45.7% (95% confidence interval, 44.5-47.0) and 19.0% (95% confidence interval, 18.6-21.2), respectively.

CONCLUSIONS

After a period of progressive improvement in GBM survival between 2000 and 2011, survival plateaued. Subsequent advances since 2011 have not yet been translated to improved survival on the population-level as of 2017.

Standardized reporting of adverse events and functional status from the first 5 years of awake surgery for gliomas: a population-based single-institution consecutive series

OBJECTIVE

To report our experience and investigate frequencies of adverse events and functional status from the first 5 years of performing awake surgery for gliomas in a single-center population-based setting.

METHODS

We conducted a review of all patients with a glioma treated with awake surgery during the first 5 years following introduction of awake surgery at our center (February 2015 to February 2020). We assessed functional and radiological outcome, with adverse events classified according to the Landriel-Ibanez classification for neurosurgical complications, while neurological deficits were further subdivided into transient vs permanent. We sought to analyze our initial results and learning curve, as well as compare our results with literature.

RESULTS

Forty-two patients were included. The median age was 38 years (range 18-66) and 13 (31%) were female. The indication for awake surgery was a presumed glioma in or near an eloquent area. The overall 30-day complication rate was 25 (59%), with 19 (45%) grade I complications, 3 (7%) grade II complications, and 3 (7%) grade III complications. Fifteen patients (36%) experienced transient neurological deficits, and 11 (26%) permanent neurological deficits. At 3-month follow-up, the Karnofsky Performance Score was 80 or higher for the entire cohort. The median extent of resection was 87%, with GTR achieved in 11 (26%). In search of potential learning curve difficulties, patients were divided into the 21 patients treated first (Early Group) versus the remaining 21 patients treated later (Late Group); no statistically significant difference in operating time, amount of tumor removed, or incidence of long-term postoperative neurological deficit was identified between groups. No awake surgery was aborted due to seizures. Comparison to the literature was limited by the diverse and unsystematic way in which previous studies have reported adverse events after awake craniotomy for gliomas.

CONCLUSION

We provide a standardized report of adverse events and functional status following awake surgery for glioma during a single-center 5-year learning period, with similar rates of severe adverse events and functional outcome compared to literature without concerns of substantial learning curve difficulties. However, this comparison was flawed by non-standardized reporting of complications, highlighting a demand for more standardized reporting of adverse events after awake craniotomies.

A New Functional Magnetic Resonance Imaging Localizer for Preoperative Language Mapping Using a Sentence Completion Task: Validity, Choice of Baseline Condition, and Test–Retest Reliability

To avoid post-neurosurgical language deficits, intraoperative mapping of the language function in the brain can be complemented with preoperative mapping with functional magnetic resonance imaging (fMRI). The validity of an fMRI “language localizer” paradigm crucially depends on the choice of an optimal language task and baseline condition. This study presents a new fMRI “language localizer” in Russian using overt sentence completion, a task that comprehensively engages the language function by involving both production and comprehension at the word and sentence level. The paradigm was validated in 18 neurologically healthy volunteers who participated in two scanning sessions, for estimating test–retest reliability. For the first time, two baseline conditions for the sentence completion task were compared. At the group level, the paradigm significantly activated both anterior and posterior language-related regions. Individual-level analysis showed that activation was elicited most consistently in the inferior frontal regions, followed by posterior temporal regions and the angular gyrus. Test–retest reliability of activation location, as measured by Dice coefficients, was moderate and thus comparable to previous studies. Test–retest reliability was higher in the frontal than temporo-parietal region and with the most liberal statistical thresholding compared to two more conservative thresholding methods. Lateralization indices were expectedly left-hemispheric, with greater lateralization in the frontal than temporo-parietal region, and showed moderate test-retest reliability. Finally, the pseudoword baseline elicited more extensive and more reliable activation, although the syllable baseline appears more feasible for future clinical use. Overall, the study demonstrated the validity and reliability of the sentence completion task for mapping the language function in the brain. The paradigm needs further validation in a clinical sample of neurosurgical patients. Additionally, the study contributes to general evidence on test–retest reliability of fMRI.

Current Status of Neuromodulation-Induced Cortical Prehabilitation and Considerations for Treatment Pathways in Lower-Grade Glioma Surgery

The infiltrative character of supratentorial lower grade glioma makes it possible for eloquent neural pathways to remain within tumoural tissue, which renders complete surgical resection challenging. Neuromodulation-Induced Cortical Prehabilitation (NICP) is intended to reduce the likelihood of premeditated neurologic sequelae that otherwise would have resulted in extensive rehabilitation or permanent injury following surgery. This review aims to conceptualise current approaches involving Repetitive Transcranial Magnetic Stimulation (rTMS-NICP) and extraoperative Direct Cortical Stimulation (eDCS-NICP) for the purposes of inducing cortical reorganisation prior to surgery, with considerations derived from psychiatric, rehabilitative and electrophysiologic findings related to previous reports of prehabilitation. Despite the promise of reduced risk and incidence of neurologic injury in glioma surgery, the current data indicates a broad but compelling possibility of effective cortical prehabilitation relating to perisylvian cortex, though it remains an under-explored investigational tool. Preliminary findings may prove sufficient for the continued investigation of prehabilitation in small-volume lower-grade tumour or epilepsy patients. However, considering the very low number of peer-reviewed case reports, optimal stimulation parameters and duration of therapy necessary to catalyse functional reorganisation remain equivocal. The non-invasive nature and low risk profile of rTMS-NICP may permit larger sample sizes and control groups until such time that eDCS-NICP protocols can be further elucidated.

Awake craniotomy using a high-flow nasal cannula with oxygen reserve index monitoring - A report of two cases

BACKGROUND

Awake craniotomy is a well-tolerated procedure for the resection of brain tumors residing within or close to the eloquent cortical areas. Monitored anesthesia care (MAC) is a dominant anesthetic approach for awake craniotomy; however, it is associated with inherent challenges such as desaturation and hypercapnia, which may lead to various complications. The prevention of respiratory insufficiency is important for successful awake craniotomy. As measures to avoid respiratory depression, the use of high-flow nasal cannula (HFNC) can improve patient oxygenation and monitor the monitoring the oxygen reserve index (ORi) can detect hypoxia earlier.

CASE

We report two cases of awake craniotomy with MAC using HFNC and ORi. We adjusted the fraction of inspired oxygen of the HFNC according to the ORi level. The patient underwent successful awake craniotomy without a desaturation event or additional airway intervention.

CONCLUSIONS

Combined HFNC and ORi monitoring may provide adequate oxygen reserves in patients undergoing awake craniotomy.

Eigenvector PageRank difference as a measure to reveal topological characteristics of the brain connectome for neurosurgery

PURPOSE

Applying graph theory to the human brain has the potential to help prognosticate the impacts of intracerebral surgery. Eigenvector (EC) and PageRank (PR) centrality are two related, but uniquely different measures of nodal centrality which may be utilized together to reveal varying neuroanatomical characteristics of the brain connectome.

METHODS

We obtained diffusion neuroimaging data from a healthy cohort (UCLA consortium for neuropsychiatric phenomics) and applied a personalized parcellation scheme to them. We ranked parcels based on weighted EC and PR, and then calculated the difference (EP difference) and correlation between the two metrics. We also compared the difference between the two metrics to the clustering coefficient.

RESULTS

While EC and PR were consistent for top and bottom ranking parcels, they differed for mid-ranking parcels. Parcels with a high EC centrality but low PR tended to be in the medial temporal and temporooccipital regions, whereas PR conferred greater importance to multi-modal association areas in the frontal, parietal and insular cortices. The EP difference showed a weak correlation with clustering coefficient, though there was significant individual variation.

CONCLUSIONS

The relationship between PageRank and eigenvector centrality can identify distinct topological characteristics of the brain connectome such as the presence of unimodal or multimodal association cortices. These results highlight how different graph theory metrics can be used alone or in combination to reveal unique neuroanatomical features for further clinical study.

Impact of Anticipated Awake Surgery on Psychooncological Distress in Brain Tumor Patients

Background

Brain tumor patients present high rates of distress, anxiety, and depression, in particular perioperatively. For resection of eloquent located cerebral lesions, awake surgery is the gold standard surgical method for the preservation of speech and motor function, which might be accompanied by increased psychological distress. The aim of the present study was to analyze if patients who are undergoing awake craniotomy suffer from increased prevalence or higher scores in distress, anxiety, or depression.

Methods

Patients, who were electively admitted for brain tumor surgery at our neurooncological department, were perioperatively screened regarding distress, anxiety, and quality of life using three established self-assessment instruments (Hospital Anxiety and Depression Scale, distress thermometer, and European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30-BN20). Screening results were correlated regarding operation technique (awake vs. general anesthesia). Retrospective statistical analyses for nominal variables were conducted using chi-square test. Metric variables were analyzed using the Kruskal–Wallis test, the Mann–Whitney U-test, and independent-samples t-tests.

Results

Data from 54 patients (26 male and 28 female) aged 29 to 82 years were available for statistical analyses. A total of 37 patients received primary resection and 17 recurrent tumor resection. Awake surgery was performed in 35 patients. There was no significant difference in awake versus non-awake surgery patients regarding prevalence (of distress (p = 0.465), anxiety (p = 0.223), or depression (p = 0.882). Furthermore, awake surgery had no significant influence on distress thermometer score (p = 0.668), anxiety score (p = 0.682), or depression score (p = 0.630) as well as future uncertainty (p = 0.436) or global health status (p = 0.943). Additionally, analyses revealed that primary or recurrent surgery also did not have any significant influence on the prevalence or scoring of the evaluated items.

Conclusion

Analyses of our cohort’s data suggest that planned awake surgery might not have a negative impact on patients concerning the prevalence and severity of manifestation of distress, anxiety, or depression in psychooncological screening. Patients undergoing recurrent surgery tend to demonstrate increased distress, although results were not significant.

An Update of Neuroanesthesia for Intraoperative Brain Mapping Craniotomy

The perioperative multidisciplinary team approach has probably been best exemplified by the care of awake craniotomy patients. Advancement in anesthesia and meticulous perioperative care has supported the safety and complexity of the surgical and mapping efforts in glioma resection. The discussions in this review will emphasize on anesthetic and perioperative management strategies to prevent complications and minimize their effects if they occur, including current practice guidelines in anesthesia, updates on the applications of anesthetic medications, and emerging devices. Planning the anesthetic and perioperative management is based on understanding the pharmacology of the medications, the goals of different stages of the surgery and mapping, and anticipating potential problems.

A Nationwide Questionnaire Survey on Awake Craniotomy in Japan

The number of awake craniotomies is increasing because of its beneficial features. However, not enough information is available regarding the current status of awake craniotomy in Japan. To evaluate the current status of awake craniotomy in institutes, a nationwide questionnaire survey was conducted. From June to August 2019, we conducted a questionnaire survey on awake craniotomy in the neurosurgery department of 45 institutes that perform awake craniotomies in Japan. Responses were obtained from 39 institutes (response rate, 86.7%). The main methods of awake craniotomy were almost the same in all institutes. Twenty-six institutes (66.7%) had fewer than 10 awake craniotomies (low-volume institutes) per year, and 13 high-volume institutes (33.3%) performed more than 10 awake craniotomies annually. Some institutes experienced a relatively high frequency of adverse events. In 11 institutes (28.2%), the frequency of intraoperative seizures was more than 10%. An intraoperative seizure frequency of 1%-9%, 10%-29%, and over 30% was identified in 12 (92%), 0 (0%), and 1 (8%) of the high-volume institutes, which was significantly less than in 16 (62%), 10 (38%), and 0 (0%) of the low-volume institutes (p = 0.0059). The routine usage of preoperative antiepileptic drugs was not different between them, but the old type was used more often in the low-volume institutes (p = 0.0022). Taken together, the annual number of awake craniotomies was less than 10 in over two-thirds of the institutes. Fewer intraoperative seizures were reported in the high-volume institutes, which tend not to preoperatively use the old type of antiepileptic drugs.

The Effect of Right Temporal Lobe Gliomas on Left and Right Hemisphere Neural Processing During Speech Perception and Production Tasks

Using fMRI, we investigated how right temporal lobe gliomas affecting the posterior superior temporal sulcus alter neural processing observed during speech perception and production tasks. Behavioural language testing showed that three pre-operative neurosurgical patients with grade 2, grade 3 or grade 4 tumours had the same pattern of mild language impairment in the domains of object naming and written word comprehension. When matching heard words for semantic relatedness (a speech perception task), these patients showed under-activation in the tumour infiltrated right superior temporal lobe compared to 61 neurotypical participants and 16 patients with tumours that preserved the right postero-superior temporal lobe, with enhanced activation within the (tumour-free) contralateral left superior temporal lobe. In contrast, when correctly naming objects (a speech production task), the patients with right postero-superior temporal lobe tumours showed higher activation than both control groups in the same right postero-superior temporal lobe region that was under-activated during auditory semantic matching. The task dependent pattern of under-activation during the auditory speech task and over-activation during object naming was also observed in eight stroke patients with right hemisphere infarcts that affected the right postero-superior temporal lobe compared to eight stroke patients with right hemisphere infarcts that spared it. These task-specific and site-specific cross-pathology effects highlight the importance of the right temporal lobe for language processing and motivate further study of how right temporal lobe tumours affect language performance and neural reorganisation. These findings may have important implications for surgical management of these patients, as knowledge of the regions showing functional reorganisation may help to avoid their inadvertent damage during neurosurgery.

Association of Neurological Impairment on the Relative Benefit of Maximal Extent of Resection in Chemoradiation-Treated Newly Diagnosed Isocitrate Dehydrogenase Wild-Type Glioblastoma

BACKGROUND

Increases in the extent of resection of both contrast-enhanced (CE) and non-contrast-enhanced (NCE) tissue are associated with substantial survival benefits in patients with isocitrate dehydrogenase wild-type glioblastoma. The fact, however, remains that these lesions exist within the framework of complex neural circuitry subserving cognition, movement, and behavior, all of which affect the ultimate survival outcome. The prognostic significance of the interplay between CE and NCE cytoreduction and neurological morbidity is poorly understood.

OBJECTIVE

To identify a clinically homogenous population of 228 patients with newly diagnosed isocitrate dehydrogenase wild-type glioblastoma, all of whom underwent maximal safe resection of CE and NCE tissue and adjuvant chemoradiation. We then set out to delineate the competing interactions between resection of CE and NCE tissue and postoperative neurological impairment with respect to overall survival.

METHODS

Nonparametric multivariate models of survival were generated via recursive partitioning to provide a clinically intuitive framework for the prognostication and surgical management of such patients.

RESULTS

We demonstrated that the presence of a new postoperative neurological impairment was the key factor in predicting survival outcomes across the entire cohort. Patients older than 60 yr who suffered from at least one new impairment had the worst survival outcome regardless of extent of resection (median of 11.6 mo), whereas those who did not develop a new impairment had the best outcome (median of 28.4 mo) so long as all CE tissue was resected.

CONCLUSION

Our data provide novel evidence for management strategies that prioritize safe and complete resection of CE tissue.

Balancing task sensitivity with reliability for multimodal language assessments

OBJECTIVE

Intraoperative tasks for awake language mapping are typically selected based on the language tracts that will likely be encountered during tumor resection. However, diminished attention and arousal secondary to perioperative sedatives may reduce a task's usefulness for identifying eloquent cortex. For instance, accuracy in performing select language tasks may be high preoperatively but decline in the operating room. In the present study, the authors sought to identify language tasks that can be performed with high accuracy in both situational contexts so the neurosurgical team can be confident that speech errors committed during awake language mapping result from direct cortical stimulation to eloquent cortex, rather than from poor performance in general.

METHODS

We administered five language tasks to 44 patients: picture naming (PN), text reading (TR), auditory object naming (AN), repetition of 4-syllable words (4SYL), and production of syntactically intact sentences (SYNTAX). Performance was assessed using the 4-point scale of the quick aphasia battery 24 hours preoperatively and intraoperatively. We next determined whether or not accuracy on each task was higher preoperatively than intraoperatively. We also determined whether 1) intraoperative accuracy on a given task predicted intraoperative performance on the other tasks and 2) low preoperative accuracy on a task predicted a decrease in accuracy intraoperatively.

RESULTS

Relative to preoperative accuracy, intraoperative accuracy declined on PN (3.90 vs 3.82, p = 0.0001), 4SYL (3.96 vs 3.91, p = 0.0006), and SYNTAX (3.85 vs 3.67, p = 0.0001) but not on TR (3.96 vs 3.94, p = 0.13) or AN (3.70 vs 3.58, p = 0.058). Intraoperative accuracy on PN and AN independently predicted intraoperative accuracy on the remaining language tasks (p < 0.001 and p < 0.01, respectively). Finally, low preoperative accuracy on SYNTAX predicted a decrease in accuracy on this task intraoperatively (R2 = 0.36, p = 0.00002).

CONCLUSIONS

While TR lacks sensitivity in identifying language deficits at baseline, accuracy on TR is stable across testing settings. Baseline accuracy on the other four of our five language tasks was not predictive of intraoperative performance, signifying the need to repeat language tests prior to stimulation mapping to confirm reliability.

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.

Awake Craniotomy for Resection of Intracranial Meningioma: First Case Series From a Low- and Middle-Income Country

Introduction

Awake craniotomy (AC) has emerged as a better modality for resection of intra-axial brain tumors. The advantages are not just related to the preservation of neurological function, but also include early recovery, short hospital stay and possibly lower costs. However, data on AC for meningioma resection is deficient, likely because of concerns related to intra-operative pain and blood loss.

Methods

All patients who underwent AC, using awake through-out technique for resection of meningioma, during the last five years, were included in the study. Non-probability consecutive sampling technique was employed. Variables for demographics, and details of diagnosis and surgical procedure were recorded. The outcomes measured were length of hospital stay, worsening of neurological function during surgery and significant intra-operative or post-operative pain.

Results

Seventeen patients underwent AC for resection of meningioma during the study period. Eleven of these were grade I meningioma, and six were grade II meningioma. The mean age was 45.8 ± 10.5 years. Presenting complaints were variable, with seizures being the most common (n = 7; 41.2%). The mean duration of surgery was 180.8 ± 36.2 minutes and median estimated blood loss was 450 ml (IQR: 225 ml - 737.5 ml). The mean length of stay in the hospital was 3.1 ± 1.3 days. Only one patient had a prolonged hospital stay of seven days, because of post-operative seizures. Eleven patients (58.3%) had convexity meningioma, 4 (33.3%) had parasagittal meningioma and 1 each had a parafalcine and anterior skull-base meningioma. Simpson grade I resection was performed in 6 (41.7%) patients, grade II resection in 10 (50%) patients, and grade III resection in 1 (5.9%) patient. None of our patients had deterioration in their neurological deficits after surgery and no one required emergency intubation, conversion of surgery to general anesthesia, or redo exploration.

Conclusion

AC may be considered a safe modality for surgical resection of convexity and parasagittal meningioma, with no significant risk of intra-operative or post-operative pain, although it requires more evidence. It can be offered to patients who are at higher risk, or are not willing to undergo general anesthesia. Ultimately, it might also be beneficial in terms of reducing overall costs.

Functional alterations in cortical processing of speech in glioma-infiltrated cortex

Recent developments in the biology of malignant gliomas have demonstrated that glioma cells interact with neurons through both paracrine signaling and electrochemical synapses. Glioma-neuron interactions consequently modulate the excitability of local neuronal circuits, and it is unclear the extent to which glioma-infiltrated cortex can meaningfully participate in neural computations. For example, gliomas may result in a local disorganization of activity that impedes the transient synchronization of neural oscillations. Alternatively, glioma-infiltrated cortex may retain the ability to engage in synchronized activity in a manner similar to normal-appearing cortex but exhibit other altered spatiotemporal patterns of activity with subsequent impact on cognitive processing. Here, we use subdural electrocorticography to sample both normal-appearing and glioma-infiltrated cortex during speech. We find that glioma-infiltrated cortex engages in synchronous activity during task performance in a manner similar to normal-appearing cortex but recruits a diffuse spatial network. On a temporal scale, we show that signals from glioma-infiltrated cortex have decreased entropy, which may affect its ability to encode information during nuanced tasks such as production of monosyllabic versus polysyllabic words. Furthermore, we show that temporal decoding strategies for distinguishing monosyllabic from polysyllabic words were feasible for signals arising from normal-appearing cortex but not from glioma-infiltrated cortex. These findings inform our understanding of cognitive processing in chronic disease states and have implications for neuromodulation and prosthetics in patients with malignant gliomas.

Tumor location-based classification of surgery-related language impairments in patients with glioma

INTRODUCTION

Many patients with glioma experience surgery-related language impairment. This study developed a classification system to predict postoperative language prognosis.

METHODS

Sixty-eight patients were retrospectively reviewed. Based on their location, tumors were subtyped as follows: (I) inferior frontal lobe or precentral gyrus; (II) posterior central gyrus or supramarginal gyrus (above the lateral fissure level); (III) posterior region of the superior or middle temporal gyri or supramarginal gyrus (below the lateral fissure level); and (IV) insular lobe. The distance from the tumor to the superior longitudinal fasciculus/arcuate fasciculus was calculated. The recovery of language function was assessed using the Western Aphasia Battery before surgery, and a comprehensive language test was conducted on the day of surgery; 3, 7, and 14 days after surgery. Our follow-up information of was the comprehensive language test from telephone interviews in 3 months after surgery.

RESULTS

Thirty-three patients experienced transient language impairment within 1 week of surgery. Fourteen patients had permanent language impairment. Type II tumors, shorter distance from the tumor to the posterior superior longitudinal fasciculus/arcuate fasciculus, and isocitrate dehydrogenase mutations were risk factors for surgery-related language impairment. Regarding the presence or absence of permanent surgery-related language impairments, the cut-off distance between the tumor and posterior superior longitudinal fasciculus/arcuate fasciculus was 2.75 mm.

CONCLUSIONS

According to our classification, patients with type II tumors had the worst language prognosis and longest recovery time. Our classification, based on tumor location, can reliably predict postoperative language status and may be used to guide tumor resection.

Intraoperative seizure outcome of levetiracetam combined with perampanel therapy in patients with glioma undergoing awake brain surgery

OBJECTIVE

This study aimed to evaluate the efficacy of levetiracetam (LEV) combined with perampanel (PER) therapy for intraoperative seizure treatment to determine whether a combination of LEV and PER can aid in the prevention of intraoperative intractable seizures during awake surgery.

METHODS

The authors performed a retrospective cohort study in 78 consecutive patients with glioma who underwent awake surgery using intraoperative direct electrical stimulation mapping. To prevent intraoperative seizures, 50 patients were treated with the antiepileptic drug LEV only (LEV group) from January 2017 to January 2019, while the remaining 28 patients were treated with LEV plus PER (LEV + PER group) between March 2019 and January 2020. LEV (1000-3000 mg) and/or PER (2-4 mg) were administered before the surgery.

RESULTS

Preoperative seizures with International League Against Epilepsy (ILAE) class II-VI occurred in 44% of the patients in the LEV group and in 35.7% of patients in the LEV + PER group, with no significant difference between groups (p = 0.319). Total intraoperative seizures occurred in 18 patients (36.0%) in the LEV therapy group and in 2 patients (7.1%) in the LEV + PER group (p = 0.009). Of these, there were no patients (0%) with intractable seizures in the LEV + PER group. Regarding factors that influence intraoperative seizures in glioma patients during awake brain surgery, multivariate logistic regression models revealed that the occurrence of intraoperative seizures was significantly related to the involvement of motor-related regions (positive vs negative, HR 6.98, 95% CI 1.71-28.56, p = 0.007), preoperative seizure (ILAE class II-VI vs ILAE class I, HR 4.44, 95% CI 1.22-16.11, p = 0.024), and LEV + PER group (positive vs negative, HR 0.07, 95% CI 0.01-0.44, p = 0.005). Treatment-related adverse effects were rare and mild, including sleepiness, tiredness, and dizziness in both treatment groups.

CONCLUSIONS

This study demonstrates that LEV + PER therapy is significantly associated with a lower risk of intraoperative seizures compared with LEV therapy alone in patients with glioma during awake brain mapping. These findings will help neurosurgeons conduct safe and reliable awake surgeries and reduce the rate of intraoperative intractable seizures during such procedures.

Glioma-Targeted Therapeutics: Computer-Aided Drug Design Prospective

Amongst the several types of brain cancers known to humankind, glioma is one of the most severe and life-threatening types of cancer, comprising 40% of all primary brain tumors. Recent reports have shown the incident rate of gliomas to be 6 per 100,000 individuals per year globally. Despite the various therapeutics used in the treatment of glioma, patient survival rate remains at a median of 15 months after undergoing first-line treatment including surgery, radiation, and chemotherapy with Temozolomide. As such, the discovery of newer and more effective therapeutic agents is imperative for patient survival rate. The advent of computer-aided drug design in the development of drug discovery has emerged as a powerful means to ascertain potential hit compounds with distinctively high therapeutic effectiveness against glioma. This review encompasses the recent advances of bio-computational in-silico modeling that have elicited the discovery of small molecule inhibitors and/or drugs against various therapeutic targets in glioma. The relevant information provided in this report will assist researchers, especially in the drug design domains, to develop more effective therapeutics against this global disease.

The Role of Delayed Radiotherapy Initiation in Patients with Newly Diagnosed Glioblastoma with Residual Tumor Mass

OBJECTIVE

 Treatment for newly diagnosed isocitrate dehydrogenase (IDH) wild-type glioblastoma (GBM) includes maximum safe resection, followed by adjuvant radio(chemo)therapy (RCx) with temozolomide. There is evidence that it is safe for GBM patients to prolong time to irradiation over 4 weeks after surgery. This study aimed at evaluating whether this applies to GBM patients with different levels of residual tumor volume (RV).

METHODS

 Medical records of all patients with newly diagnosed GBM at our department between 2014 and 2018 were reviewed. Patients who received adjuvant radio (chemo) therapy, aged older than 18 years, and with adequate perioperative imaging were included. Initial and residual tumor volumes were determined. Time to irradiation was dichotomized into two groups (≤28 and >28 days). Univariate analysis with Kaplan-Meier estimate and log-rank test was performed. Survival prediction and multivariate analysis were performed employing Cox proportional hazard regression.

RESULTS

 One hundred and twelve patients were included. Adjuvant treatment regimen, extent of resection, residual tumor volume, and O⁶-methylguanine DNA methyltransferase (MGMT) promoter methylation were statistically significant factors for overall survival (OS). Time to irradiation had no impact on progression-free survival (p = 0.946) or OS (p = 0.757). When stratified for different thresholds of residual tumor volume, survival predication via Cox regression favored time to irradiation below 28 days for patients with residual tumor volume above 2 mL, but statistical significance was not reached.

CONCLUSION

 Time to irradiation had no significant influence on OS of the entire cohort. Nevertheless, a statistically nonsignificant survival prolongation could be observed in patients with residual tumor volume > 2 mL when admitted to radiotherapy within 28 days after surgery.

Intraoperative panic attack in patients undergoing awake craniotomy: a retrospective analysis of risk factors

PURPOSE

Intraoperative anxiety is the most common psychological response of the patient during awake craniotomy. Psychological stress can trigger patient decline, resulting in failed awake craniotomy and significantly poor outcomes. This study aimed to identify the risk factors for panic attack (PA) during awake craniotomies.

METHODS

With the local ethics committee approval, we conducted a manual chart review of the medical record of patients who underwent consecutive awake craniotomies between November 1999 and October 2016 at Tokyo Women's Medical University. A total of 405 patients were identified and assigned to 2 groups based on the Diagnostic and Statistical Manual of Mental Disorders-V criteria: those that met the PA criteria (Group PA) and those that did not (Group non-PA). Patient characteristics and the incidence of the PA specifier were collected. The features of the two groups were statistically compared, and risk factors for PA occurrence were determined by regression analysis.

RESULTS

Sixteen of 405 patients met the diagnostic criteria of PA. Patients' characteristics were not statistically different between the groups. Multivariate logistic regression showed that intraoperative anxiety (p = 0.0002) and age younger than 39 years (as opposed to age >  = 39 years; p = 0.0328) were significantly associated with the occurrence of PA during awake craniotomy.

CONCLUSIONS

For patients undergoing awake craniotomy, intraoperative anxiety and age younger than 39 years were considered risk factors of PA. As PA often necessitates conversion to general anesthesia, intensive perioperative psychological support and pain management are required to achieve patient satisfaction and the surgical goal of awake craniotomy.

Surgery of Insular Diffuse Gliomas-Part 2: Probabilistic Cortico-Subcortical Atlas of Critical Eloquent Brain Structures and Probabilistic Resection Map During Transcortical Awake Resection

BACKGROUND

Insular diffuse glioma surgery is challenging, and tools to help surgical planning could improve the benefit-to-risk ratio.

OBJECTIVE

To provide a probabilistic resection map and frequency atlases of critical eloquent regions of insular diffuse gliomas based on our surgical experience.

METHODS

We computed cortico-subcortical "eloquent" anatomic sites identified intraoperatively by direct electrical stimulations during transcortical awake resection of insular diffuse gliomas in adults.

RESULTS

From 61 insular diffuse gliomas (39 left, 22 right; all left hemispheric dominance for language), we provided a frequency atlas of eloquence of the opercula (left/right; pars orbitalis: 0%/5.0%; pars triangularis: l5.6%/4.5%; pars opercularis: 37.8%/27.3%; precentral gyrus: 97.3%/95.4%; postcentral and supramarginal gyri: 75.0%/57.1%; temporal pole and superior temporal gyrus: 13.3%/0%), which tailored the transcortical approach (frontal operculum to reach the antero-superior insula, temporal operculum to reach the inferior insula, parietal operculum to reach the posterior insula). We provided a frequency atlas of eloquence identifying the subcortical functional boundaries (36.1% pyramidal pathways, 50.8% inferior fronto-occipital fasciculus, 13.1% arcuate and superior longitudinal fasciculi complex, 3.3% somatosensory pathways, 8.2% caudate and lentiform nuclei). Vascular boundaries and increasing errors during testing limited the resection in 8.2% and 11.5% of cases, respectively. We provided a probabilistic 3-dimensional atlas of resectability.

CONCLUSION

Functional mapping under awake conditions has to be performed intraoperatively in each patient to guide surgical approach and resection of insular diffuse gliomas in right and left hemispheres. Frequency atlases of opercula eloquence and of subcortical eloquent anatomic boundaries, and probabilistic 3-dimensional atlas of resectability could guide neurosurgeons.

Surgery of Insular Diffuse Gliomas-Part 1: Transcortical Awake Resection Is Safe and Independently Improves Overall Survival

BACKGROUND

Insular diffuse glioma resection is at risk of vascular injury and of postoperative new neurocognitive deficits.

OBJECTIVE

To assess safety and efficacy of surgical management of insular diffuse gliomas.

METHODS

Observational, retrospective, single-institution cohort analysis (2005-2019) of 149 adult patients surgically treated for an insular diffuse glioma: transcortical awake resection with intraoperative functional mapping (awake resection subgroup, n = 61), transcortical asleep resection without functional mapping (asleep resection subgroup, n = 50), and stereotactic biopsy (biopsy subgroup, n = 38). All cases were histopathologically assessed according to the 2016 World Health Organization classification and cIMPACT-NOW update 3.

RESULTS

Following awake resection, 3/61 patients had permanent motor deficit, seizure control rates improved (89% vs 69% preoperatively, P = .034), and neurocognitive performance improved from 5% to 24% in tested domains, despite adjuvant oncological treatments. Resection rates were higher in the awake resection subgroup (median 94%) than in the asleep resection subgroup (median 46%; P < .001). There was more gross total resection (25% vs 12%) and less partial resection (34% vs 80%) in the awake resection subgroup than in the asleep resection subgroup (P < .001). Karnofsky Performance Status score <70 (adjusted hazard ratio [aHR] 2.74, P = .031), awake resection (aHR 0.21, P = .031), isocitrate dehydrogenase (IDH)-mutant grade 2 astrocytoma (aHR 5.17, P = .003), IDH-mutant grade 3 astrocytoma (aHR 6.11, P < .001), IDH-mutant grade 4 astrocytoma (aHR 13.36, P = .008), and IDH-wild-type glioblastoma (aHR 21.84, P < .001) were independent predictors of overall survival.

CONCLUSION

Awake surgery preserving the brain connectivity is safe, allows larger resections for insular diffuse gliomas than asleep resection, and positively impacts overall survival.

Surgical management of incidentally discovered low-grade gliomas

OBJECTIVE

Although most patients with low-grade glioma (LGG) present after a seizure, a small proportion is diagnosed after neuroimaging is performed for a sign or symptom unrelated to the tumor. While these tumors invariably grow, some surgeons argue for a watchful waiting approach. Here, the authors report on their experience in the surgical treatment of patients with incidental LGG (iLGG) and describe the neurological outcomes, survival, and complications.

METHODS

Relevant cases were identified from a prospective registry of patients undergoing glioma resection at the University of California, San Francisco, between 1997 and 2019. Cases were considered iLGG when the lesion was noted on imaging performed for a reason unrelated to the tumor. Demographic, clinical, pathological, and imaging data were extracted from the electronic medical record. Tumor volumes, growth, and extent of resection were calculated from pre- and postoperative volumetric FLAIR sequences.

RESULTS

One hundred thirteen of 657 (17.2%) first-time resections for LGG were for incidental lesions. The most common reasons for the discovery of an iLGG were headaches (without mass effect, 34.5%) or trauma (16.8%). Incidental tumors were no different from symptomatic lesions in terms of laterality or location, but they were significantly smaller (22.5 vs 57.5 cm3, p < 0.0001). There was no difference in diagnosis between patients with iLGG and those with symptomatic LGG (sLGG), incorporating both molecular and pathological data. The median preoperative observation time for iLGG was 3.1 months (range 1 month-12 years), and there was a median growth rate of 3.9 cm3/year. Complete resection of the FLAIR abnormality was achieved in 57% of patients with incidental lesions but only 23.8% of symptomatic lesions (p < 0.001), and the residual volumes were smaller for iLGGs (2.9 vs 13.5 cm3, p < 0.0001). Overall survival was significantly longer for patients with incidental tumors (median survival not reached for patients with iLGG vs 14.6 years for those with sLGG, p < 0.0001). There was a 4.4% rate of neurological deficits at 6 months.

CONCLUSIONS

The authors present the largest cohort of iLGGs. Patient age, tumor location, and molecular genetics were not different between iLGGs and sLGGs. Incidental tumors were smaller, a greater extent of resection could be achieved, and overall survival was improved compared to those for patients with sLGG. Operative morbidity and rates of neurological deficit were acceptably low; thus, the authors advocate upfront surgical intervention aimed at maximal safe resection for these incidentally discovered lesions.

The Relationship Between Stimulation Current and Functional Site Localization During Brain Mapping

BACKGROUND

Gliomas are often in close proximity to functional regions of the brain; therefore, electrocortical stimulation (ECS) mapping is a common technique utilized during glioma resection to identify functional areas. Stimulation-induced seizure (SIS) remains the most common reason for aborted procedures. Few studies have focused on oncological factors impacting cortical stimulation thresholds.

OBJECTIVE

To examine oncological factors thought to impact stimulation threshold in order to understand whether a linear relationship exists between stimulation current and number of functional cortical sites identified.

METHODS

We retrospectively reviewed single-institution prospectively collected brain mapping data of patients with dominant hemisphere gliomas. Comparisons of stimulation threshold were made using t-tests and ANOVAs. Associations between oncologic factors and stimulation threshold were made using multivariate regressions. The association between stimulation current and number of positive sites was made using a Poisson model.

RESULTS

Of the 586 patients included in the study, SIS occurred in 3.92% and the rate of SIS events differed by cortical location (frontal 8.5%, insular 1.6%, parietal 1.3%, and temporal 2.8%; P = .009). Stimulation current was lower when mapping frontal cortex (P = .002). Stimulation current was not associated with tumor plus peritumor edema volume, world health organization) (WHO grade, histology, or isocitrate dehydrogenase (IDH) mutation status but was associated with tumor volume within the frontal lobe (P = .018). Stimulation current was not associated with number of positive sites identified during ECS mapping (P = .118).

CONCLUSION

SISs are rare but serious events during ECS mapping. SISs are most common when mapping the frontal lobe. Greater stimulation current is not associated with the identification of more cortical functional sites during glioma surgery.

The PROGRAM study: awake mapping versus asleep mapping versus no mapping for high-grade glioma resections: study protocol for an international multicenter prospective three-arm cohort study

INTRODUCTION

The main surgical dilemma during glioma resections is the surgeon's inability to accurately identify eloquent areas when the patient is under general anaesthesia without mapping techniques. Intraoperative stimulation mapping (ISM) techniques can be used to maximise extent of resection in eloquent areas yet simultaneously minimise the risk of postoperative neurological deficits. ISM has been widely implemented for low-grade glioma resections backed with ample scientific evidence, but this is not yet the case for high-grade glioma (HGG) resections. Therefore, ISM could thus be of important value in HGG surgery to improve both surgical and clinical outcomes.

METHODS AND ANALYSIS

This study is an international, multicenter, prospective three-arm cohort study of observational nature. Consecutive HGG patients will be operated with awake mapping, asleep mapping or no mapping with a 1:1:1 ratio. Primary endpoints are: (1) proportion of patients with National Institute of Health Stroke Scale deterioration at 6 weeks, 3 months and 6 months after surgery and (2) residual tumour volume of the contrast-enhancing and non-contrast-enhancing part as assessed by a neuroradiologist on postoperative contrast MRI scans. Secondary endpoints are: (1) overall survival and (2) progression-free survival at 12 months after surgery; (3) oncofunctional outcome and (4) frequency and severity of serious adverse events in each arm. Total duration of the study is 5 years. Patient inclusion is 4 years, follow-up is 1 year.

ETHICS AND DISSEMINATION

The study has been approved by the Medical Ethics Committee (METC Zuid-West Holland/Erasmus Medical Center; MEC-2020-0812). The results will be published in peer-reviewed academic journals and disseminated to patient organisations and media.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov ID number NCT04708171 (PROGRAM-study), NCT03861299 (SAFE-trial).

Awake craniotomy for glioblastoma in COVID-19–positive patients and delivering the standard of care: illustrative case

BACKGROUND

Providing the standard of care to patients with glioblastoma (GBM) during the novel coronavirus of 2019 (COVID-19) pandemic is a challenge, particularly if a patient tests positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Further difficulties occur in eloquent cortex tumors because awake speech mapping can theoretically aerosolize viral particles and expose staff. Moreover, microscopic neurosurgery has become difficult because the use of airborne-level personal protective equipment (PPE) crowds the space between the surgeon and the eyepiece. However, delivering substandard care will inevitably lead to disease progression and poor outcomes.

OBSERVATIONS

A 60-year-old man with a left insular and frontal operculum GBM was found to be COVID-19 positive. Treatment was postponed pending a negative SARS-CoV-2 result, but in the interim, he developed intratumoral hemorrhage with progressive expressive aphasia. Because the tumor was causing dominant hemisphere language symptomatology, an awake craniotomy was the recommended surgical approach. With the use of airborne-level PPE and a surgical drape to protect the surgeon from the direction of potential aerosolization, near-total gross resection was achieved.

LESSONS

Delaying the treatment of patients with GBM who test positive for COVID-19 will lead to further neurological deterioration. Optimal and timely treatment such as awake speech mapping for COVID-19–positive patients with GBM can be provided safely.

Machine Vision for Real-Time Intraoperative Anatomic Guidance: A Proof-of-Concept Study in Endoscopic Pituitary Surgery

BACKGROUND

Current intraoperative orientation methods either rely on preoperative imaging, are resource-intensive to implement, or difficult to interpret. Real-time, reliable anatomic recognition would constitute another strong pillar on which neurosurgeons could rest for intraoperative orientation.

OBJECTIVE

To assess the feasibility of machine vision algorithms to identify anatomic structures using only the endoscopic camera without prior explicit anatomo-topographic knowledge in a proof-of-concept study.

METHODS

We developed and validated a deep learning algorithm to detect the nasal septum, the middle turbinate, and the inferior turbinate during endoscopic endonasal approaches based on endoscopy videos from 23 different patients. The model was trained in a weakly supervised manner on 18 and validated on 5 patients. Performance was compared against a baseline consisting of the average positions of the training ground truth labels using a semiquantitative 3-tiered system.

RESULTS

We used 367 images extracted from the videos of 18 patients for training, as well as 182 test images extracted from the videos of another 5 patients for testing the fully developed model. The prototype machine vision algorithm was able to identify the 3 endonasal structures qualitatively well. Compared to the baseline model based on location priors, the algorithm demonstrated slightly but statistically significantly (P < .001) improved annotation performance.

CONCLUSION

Automated recognition of anatomic structures in endoscopic videos by means of a machine vision model using only the endoscopic camera without prior explicit anatomo-topographic knowledge is feasible. This proof of concept encourages further development of fully automated software for real-time intraoperative anatomic guidance during surgery.

Awake surgery for lesions near eloquent brain under scalp block and clinical monitoring: experience of single center with limited resources

Background

Surgery of the brain tumors near eloquent areas carries the risk of either disabling neurological deficit or inadequate resection with bad prognosis in both situations. Awake surgery is the gold standard procedure for such lesions. However, it requires certain anesthetic drugs, advanced techniques, and trained teams that are not available in every neurosurgical institute. This work aims to evaluate safety, feasibility, and outcome of operating on patients with space occupying lesions near eloquent areas under scalp block being continuously examined by a neurologist through retrospective study of 20 cases with supratentorial lesions related to language or sensorimotor cortex.

Results

There were 12 males and 8 females with mean age 36.8 years. Forty percent of patients were presented by motor weakness. Tumors were related to motor cortex in 11 patients and to language areas in 9 patients. Mean operative time was 210 min. Gross or near total resection was achieved in 15cases, four cases had subtotal resection and biopsy only was done in 1 case. Two patients suffered from intraoperative seizures and conversion to general anesthesia was required in one patient.

Conclusion

Operating on tumors near eloquent brain areas under scalp block and continuous neurological examination during tumor resection proved to be effective in early detection and prevention of permanent major deficits especially in the developing countries with limited resources.

The Greek linguistic assessment for awake brain surgery: development process and normative data

Language mapping with direct electrical stimulation is considered the gold standard in surgical treatment of brain tumors. Assessing a variety of language functions intraoperatively can affect the extent of the tumor resection as well as the patient's postoperative quality of life. Although most tests include preoperative sessions where tasks are personalised to each patient, normative data are essential since they can ensure that the presented stimuli can be responded appropriately. In this study, we describe the development and standardisation procedures of the first linguistic test in Greek, designed specifically for brain mapping during awake craniotomies. The tasks are developed to comply with the special conditions and restrictions of language assessment inside the operating room. Each task is controlled for various psycholinguistic and lexical variables and it is associated with specific neuroanatomical areas and linguistic processes. Our population consists of 80 right-handed, healthy, Greek-speaking individuals aged 20-60 years. We found only a few main effects and interactions of demographic variables on our test scores. Most differences were found between age groups, since older participants tend to perform slightly worse than younger ones. Therefore, percentiles and cut-off scores were calculated separately for each demographic group. Regarding the clinical application of GLAABS, we describe the procedures we followed to administer it to brain tumor patients from our department and also discuss how sensitivity and specificity can affect patients' postoperative course.

Incidence and linguistic quality of speech errors: a comparison of preoperative transcranial magnetic stimulation and intraoperative direct cortex stimulation

OBJECTIVE

Given the interindividual variance of functional language anatomy, risk prediction based merely on anatomical data is insufficient in language area-related brain tumor surgery, suggesting the need for direct cortical and subcortical mapping during awake surgery. Reliable, noninvasive preoperative methods of language localization hold the potential for reducing the necessity for awake procedures and may improve patient counseling and surgical planning. Repetitive navigated transcranial magnetic stimulation (rnTMS) is an evolving tool for localizing language-eloquent areas. The aim of this study was to investigate the reliability of rnTMS in locating cortical language sites.

METHODS

Twenty-five patients with brain tumors in speech-related areas were prospectively evaluated with preoperative rnTMS (5 Hz, train of five, average 105% resting motor threshold) and navigated direct cortical stimulation (DCS; bipolar, 50 Hz, 6-8 mA, 200-μsec pulse width) during awake surgeries employing a picture-naming task. Positive and negative stimulation spots within the craniotomy were documented in the same MRI data set. TMS and DCS language-positive areas were compared with regard to their spatial overlap, their allocation in a cortical parcellation system, and their linguistic qualities.

RESULTS

There were over twofold more positive language spots within the exposed area on rnTMS than on DCS. The comparison of positive rnTMS and DCS (ground truth) overlaps revealed low sensitivity (35%) and low positive predictive value (16%) but high specificity (90%) and high negative predictive value (96%). Within the overlaps, there was no correlation in error quality. On DCS, 73% of language-positive spots were located in the pars opercularis and pars triangularis of the frontal operculum and 24% within the supramarginal gyrus and dorsal portion of the superior temporal gyrus, while on rnTMS language positivity was distributed more evenly over a large number of gyri.

CONCLUSIONS

The current protocol for rnTMS for language mapping identified language-negative sites with good dependability but was unable to reliably detect language-positive spots. Further refinements of the technique will be needed to establish rnTMS language mapping as a useful clinical tool.

Preoperative factors associated with adverse events during awake craniotomy: analysis of 609 consecutive cases

OBJECTIVE

Awake surgery is becoming more standard and widely practiced for neurosurgical cases, including but not limited to brain tumors. The optimal selection of patients who can tolerate awake surgery remains a challenge. The authors performed an updated cohort study, with particular attention to preoperative clinical and imaging characteristics that may have an impact on the viability of awake craniotomy in individual patients.

METHODS

The authors conducted a single-institution cohort study of 609 awake craniotomies performed in 562 patients. All craniotomies were performed by the same surgeon at Toronto Western Hospital during the period from 2006 to 2018. Analyses of preoperative clinical and imaging characteristics that may have an impact on the viability of awake craniotomy in individual patients were performed.

RESULTS

Twenty-one patients were recorded as having experienced intraoperative adverse events necessitating deeper sedation, which made the surgery no longer "awake." In 2 of these patients, conversion to general anesthesia was performed. The adverse events included emotional intolerance of awake surgery (n = 13), air embolism (n = 3), generalized seizure (n = 4), and unexpected subarachnoid hemorrhage (n = 1). Preoperative cognitive decline, dysphasia, and low performance status, as indicated by the Karnofsky Performance Status (KPS) score, were significantly associated with emotional intolerance on univariate analysis. Only a preoperative KPS score < 70 was significantly associated with this event on multivariate analysis (p = 0.0057). Compared with patients who did not experience intraoperative adverse events, patients who did were more likely to undergo inpatient admission (p = 0.0004 for all cases; p = 0.0036 for cases originally planned as day surgery), longer hospital stay (p < 0.0001), and discharge to a location other than home (p = 0.032).

CONCLUSIONS

Preoperative physical status was found to be the most decisive factor in predicting whether patients can tolerate an awake craniotomy without complications, whereas older age and history of psychiatric treatment were not necessarily associated with adverse events. Patients who had intraoperative adverse events often had reduced chances of same-day discharge and discharge to home. Preoperative careful selection of patients who are most likely to tolerate the procedure is the key to success for awake surgery.

The perspectives of mapping and monitoring of the sense of self in neurosurgical patients

Surgical treatment of tumors, epileptic foci or of vascular origin, requires a detailed individual pre-surgical workup and intra-operative surveillance of brain functions to minimize the risk of post-surgical neurological deficits and decline of quality of life. Most attention is attributed to language, motor functions, and perception. However, higher cognitive functions such as social cognition, personality, and the sense of self may be affected by brain surgery. To date, the precise localization and the network patterns of brain regions involved in such functions are not yet fully understood, making the assessment of risks of related post-surgical deficits difficult. It is in the interest of neurosurgeons to understand with which neural systems related to selfhood and personality they are interfering during surgery. Recent neuroscience research using virtual reality and clinical observations suggest that the insular cortex, medial prefrontal cortex, and temporo-parietal junction are important components of a neural system dedicated to self-consciousness based on multisensory bodily processing, including exteroceptive and interoceptive cues (bodily self-consciousness (BSC)). Here, we argue that combined extra- and intra-operative approaches using targeted cognitive testing, functional imaging and EEG, virtual reality, combined with multisensory stimulations, may contribute to the assessment of the BSC and related cognitive aspects. Although the usefulness of particular biomarkers, such as cardiac and respiratory signals linked to virtual reality, and of heartbeat evoked potentials as a surrogate marker for intactness of multisensory integration for intra-operative monitoring has to be proved, systemic and automatized testing of BSC in neurosurgical patients will improve future surgical outcome.

Brain connectomics applied to oncological neuroscience: from a traditional surgical strategy focusing on glioma topography to a meta-network approach

The classical way for surgical selection and planning in cerebral glioma mainly focused on tumor topography. The emerging science of connectomics, which aims of mapping brain connectivity, resulted in a paradigmatic shift from a modular account of cerebral organization to a meta-network perspective. Adaptive behavior is actually mediated by constant changes in interactions within and across large-scale delocalized neural systems underlying conation, cognition, and emotion. Here, to optimize the onco-functional balance of glioma surgery, the purpose is to switch toward a connectome-based resection taking account of both relationships between the tumor and critical distributed circuits (especially subcortical pathways) as well as the perpetual instability of the meta-network. Such dynamic in the neural spatiotemporal integration permits functional reallocation leading to neurological recovery after massive resection in structures traditionally thought as "inoperable." This better understanding of connectome increases benefit/risk ratio of surgery (i) by selecting resection in areas deemed "eloquent" according to a localizationist dogma; (ii), conversely, by refining intraoperative awake cognitive mapping and monitoring in so-called non-eloquent areas; (iii) by improving preoperative information, enabling an optimal selection of intrasurgical tasks tailored to the patient's wishes; (iv) by developing an "oncological disconnection surgery"; (v) by defining a personalized multistep surgical strategy adapted to individual brain reshaping potential; and (vi) ultimately by preserving environmentally and socially appropriate behavior, including return to work, while increasing the extent of (possibly repeated) resection(s). Such a holistic vision of neural processing can enhance reliability of connectomal surgery in oncological neuroscience and may also be applied to restorative neurosurgery.

The Use of Standardized Intraoperative Language Tests in Awake Craniotomies: A Scoping Review

Assessment of speech and language functions is an essential part of awake craniotomies. Although standardized and validated tests have several advantages compared to homemade (or mixed) batteries, in the literature it is unclear how such tests are used or whether they are used at all. In this study, we performed a scoping review in order to locate standardized and validated intraoperative language tests. Our inquiry included two databases (PubMED and MEDLINE), gray literature, and snowball referencing. We discovered 87 studies reporting use of mixed batteries, which consist of homemade tasks and tests borrowed from other settings. The tests we found to meet the validation and standardization criteria we set were ultimately three (n = 3) and each one has its own advantages and disadvantages. We argue that tests with high sensitivity and specificity not only can lead to better outcomes postoperatively, but they can also help us to gain a better understanding of the neuroanatomy of language.

Characteristic Alterations of Network in Patients With Intraoperative Stimulation-Induced Seizures During Awake Craniotomy

Background: The use of electrocorticography (ECoG) to avoid intraoperative stimulation-induced seizure (ISS) during awake craniotomy is controversial. Although a standard direct cortical stimulating (DCS) protocol is used to identify the eloquent cortices and subcortical structures, ISS still occurs. Epilepsy is related to alterations in brain networks. In this study, we investigated specific alterations in brain networks in patients with ISS. Methods: Twenty-seven patients with glioma were enrolled and categorized into the ISS and non-ISS groups based on their history of ISS occurrence. A standard DCS protocol was used during awake craniotomy without ECoG supervision. Graph theoretical measurement was used to analyze resting-state functional magnetic resonance imaging data to quantitatively reveal alterations in the functional networks. Results: In the sensorimotor networks, the glioma significantly decreased the functional connectivity (FC) of four edges in the ISS group, which were conversely increased in the non-ISS group after multiple corrections (p < 0.001, threshold of p-value = 0.002). Regarding the topological properties, the sensorimotor network of all participants was classified as a small-world network. Glioma significantly increased global efficiency, nodal efficiency, and the sigma value, as well as decreased the shortest path length in the ISS group compared with the non-ISS group (p < 0.05). Conclusions: The specific alterations indicating patient susceptibility to ISS during DCS increased global and nodal efficiencies and decreased the shortest path length and FC induced by gliomas. If the patient has these specific alterations, ECoG is recommended to monitor after-discharge current during DCS to avoid ISS.

Intraoperative Cognitive Mapping Tasks for Direct Electrical Stimulation in Clinical and Neuroscientific Contexts

Direct electrical stimulation (DES) has been widely applied in both guidance of lesion resection and scientific research; however, the design and selection of intraoperative cognitive mapping tasks have not been updated in a very long time. We introduce updated mapping tasks for language and non-language functions and provide recommendations for optimal design and selection of intraoperative mapping tasks. In addition, with DES becoming more critical in current neuroscientific research, a task design that has not been widely used in DES yet (subtraction and conjunction paradigms) was introduced for more delicate mapping of brain functions especially for research purposes. We also illustrate the importance of designing a common task series for DES and other non-invasive mapping techniques. This review gives practical updated guidelines for advanced application of DES in clinical and neuroscientific research.

The impact of high functional connectivity network hub resection on language task performance in adult low- and high-grade glioma

OBJECTIVE

Gliomas are intrinsic brain tumors with the hallmark of diffuse white matter infiltration, resulting in short- and long-range network dysfunction. Preoperative magnetoencephalography (MEG) can assist in maximizing the extent of resection while minimizing morbidity. While MEG has been validated in motor mapping, its role in speech mapping remains less well studied. The authors assessed how the resection of intraoperative electrical stimulation (IES)-negative, high functional connectivity (HFC) network sites, as identified by MEG, impacts language performance.

METHODS

Resting-state, whole-brain MEG recordings were obtained from 26 patients who underwent perioperative language evaluation and glioma resection that was guided by awake language and IES mapping. The functional connectivity of an individual voxel was determined by the imaginary coherence between the index voxel and the rest of the brain, referenced to its contralesional pair. The percentage of resected HFC voxels was correlated with postoperative language outcomes in tasks of increasing complexity: text reading, 4-syllable repetition, picture naming, syntax (SYN), and auditory stimulus naming (AN).

RESULTS

Overall, 70% of patients (14/20) in whom any HFC tissue was resected developed an early postoperative language deficit (mean 2.3 days, range 1-8 days), compared to 33% of patients (2/6) in whom no HFC tissue was resected (p = 0.16). When bifurcated by the amount of HFC tissue that was resected, 100% of patients (3/3) with an HFC resection > 25% displayed deficits in AN, compared to 30% of patients (6/20) with an HFC resection < 25% (p = 0.04). Furthermore, there was a linear correlation between the severity of AN and SYN decline with percentage of HFC sites resected (p = 0.02 and p = 0.04, respectively). By 2.2 months postoperatively (range 1-6 months), the correlation between HFC resection and both AN and SYN decline had resolved (p = 0.94 and p = 1.00, respectively) in all patients (9/9) except two who experienced early postoperative tumor progression or stroke involving inferior frontooccipital fasciculus.

CONCLUSIONS

Imaginary coherence measures of functional connectivity using MEG are able to identify HFC network sites within and around low- and high-grade gliomas. Removal of IES-negative HFC sites results in early transient postoperative decline in AN and SYN, which resolved by 3 months in all patients without stroke or early tumor progression. Measures of functional connectivity may therefore be a useful means of counseling patients about postoperative risk and assist with preoperative surgical planning.

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.

Maximal surgical resection and adjuvant surgical technique to prolong the survival of adult patients with thalamic glioblastoma

The importance of maximal resection in the treatment of glioblastoma (GBM) has been reported in many studies, but maximal resection of thalamic GBM is rarely attempted due to high rate of morbidity and mortality. The purpose of this study was to investigate the role of surgical resection in adult thalamic glioblastoma (GBM) treatment and to identify the surgical technique of maximal safety resection. In case of suspected thalamic GBM, surgical resection is the treatment of choice in our hospital. Biopsy was considered when there was ventricle wall enhancement or multiple enhancement lesion in a distant location. Navigation magnetic resonance imaging, diffuse tensor tractography imaging, tailed bullets, and intraoperative computed tomography and neurophysiologic monitoring (transcranial motor evoked potential and direct subcortical stimulation) were used in all surgical resection cases. The surgical approach was selected on the basis of the location of the tumor epicenter and the adjacent corticospinal tract. Among the 42 patients, 19 and 23 patients underwent surgical resection and biopsy, respectively, according to treatment strategy criteria. As a result, the surgical resection group exhibited a good response with overall survival (OS) (median: 676 days, p < 0.001) and progression-free survival (PFS) (median: 328 days, p < 0.001) compared with each biopsy groups (doctor selecting biopsy group, median OS: 240 days and median PFS: 134 days; patient selecting biopsy group, median OS: 212 days and median PFS: 118 days). The surgical resection groups displayed a better prognosis compared to that of the biopsy groups for both the O6-methylguanine-DNA methyltransferase unmethylated (log-rank p = 0.0035) or methylated groups (log-rank p = 0.021). Surgical resection was significantly associated with better prognosis (hazard ratio: 0.214, p = 0.006). In case of thalamic GBM without ventricle wall-enhancing lesion or multiple lesions, maximal surgical resection above 80% showed good clinical outcomes with prolonged the overall survival compared to biopsy. It is helpful to use adjuvant surgical techniques of checking intraoperative changes and select the appropriate surgical approach for reducing the surgical morbidity.