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

Functional Mapping for Glioma Surgery, Part 2: Intraoperative Mapping Tools

Intraoperative functional mapping of tumor and peri-tumor tissue is a well-established technique for avoiding permanent neurologic deficits and maximizing extent of resection. Motor, language, and other cognitive domains may be assessed with intraoperative tasks. This article describes techniques used for motor and language mapping including awake mapping considerations in addition to less traditional intraoperative testing paradigms for cognition. It also discusses complications associated with mapping and insights into complication avoidance.

The Merits of Awake Craniotomy for Glioblastoma in the Left Hemispheric Eloquent Area: One Institution Experience

OBJECTIVE

Awake craniotomy (AC) with intraoperative stimulation mapping is the standard treatment for gliomas, especially those on the eloquent cortex. Many studies have reported survival benefits with the use of AC in patients with glioma, however most of these studies have focused on low-grade glioma. The aim of this study was to evaluate the experience of one treatment center over 10 years for resection of left hemispheric eloquent glioblastoma.

METHODS

This retrospective analysis included 48 patients with left hemispheric eloquent glioblastoma who underwent AC and 61 patients who underwent surgery under general anesthesia (GA) between 2008 and 2018. Perioperative risk factors, extent of resection (EOR), preoperative and postoperative Karnofsky Performance Score (KPS), progression-free survival (PFS) and overall survival (OS) were assessed.

RESULTS

The postoperative KPS was significantly lower in the GA patients compared to the AC patients (p = 0.002). The EOR in the GA group was 90.2% compared to 94.9% in the AC group (p = 0.003). The mean PFS was 18.9 months in the GA group and 23.2 months in the AC group (p = 0.001). The mean OS was 25.5 months in all patients, 23.4 months in the GA group, and 28.1 months in the AC group (p < 0.001). In multivariate analysis, the EOR and preoperative KPS independently predicted better OS.

CONCLUSION

The patients with left hemispheric eloquent glioblastoma in this study had better neurological outcomes, maximal tumor removal, and better PFS and OS after AC than surgery under GA. Awake craniotomy should be performed in these patients if the resources are available.

Result of awake surgery for pediatric eloquent brain area tumors: single-center experience

PURPOSE

About half of brain tumors are located in supratentorial regions and 20% of them in eloquent brain cortex areas. The use of fMRI and intraoperative neuromonitoring allows safe surgery of these areas. Carrying out awake brain surgery (ABS) operations provides additional opportunities for direct-function monitoring. In pediatric practice, this method has not been used widely yet.

METHODS

We present the retrospective analysis of the results of pre-operative examination and surgical treatment of 12 patients with glial tumors located in eloquent cortex areas. Two patients had ABS operations twice. Intraoperative neuromonitoring was used in all the cases.

RESULTS

Twelve patients in total underwent fourteen ABS operations. According to histology results, patients with low-grade tumors prevailed, 11 (91.7%) out of 12. Seven (58.3%) patients had the tumor located in the projection of speech cortex area, four (33.3%) patients in the motor cortex area, and one (8.4%) patient in the visual cortex area. The youngest male was 8 years old. Temporary neurological deficit was diagnosed in three (25%) cases. The tumor was removed completely in 66.7% (eight) cases. Three patients were operated upon twice, two of whom had ABS operations twice. The awake phase of the surgery lasted from 30 to 110 min, 61.2 min on average.

CONCLUSIONS

Our experience has shown sufficient safety of pediatric ABS operations. The achieved functional result and radicality of tumor removal prove that further application and development of this method for children with eloquent brain area tumors (EBATs) is reasonable.

[Sensations of patients and their satisfaction during awake craniotomy]

Awake craniotomy (AC) has gained fantastic popularity over the past years. This approach is no longer the destiny of only highly specialized neurosurgical centers. Technical features of AC are completely developed. However, certain aspects of patients' sensations and their satisfaction are still unclear. The review is devoted to these issues. It was shown that AC is positively evaluated by the vast majority of patients. Many patients would choose this technique for redo surgery. However, there are certain important details that can adversely affect satisfaction of patients. Thus, these features should be considered in AC.

Glioma surgery with awake language mapping versus generalized anesthesia: a systematic review

Awake craniotomy with language mapping is being increasingly applied to avoid postoperative language dysfunctions worldwide. However, the effectiveness and reliability of this technique remain unclear due to the paucity of studies comparing the awake craniotomy with general anesthesia. To determine the benefit of awake craniotomy for language, motor, and neurological functions, as well as other clinical outcomes, we searched Medline, Embase, the Cochrane Library, and the Chinese Biomedical Literature Database up to December 2019. Gray literatures were also searched. We included randomized and non-randomized controlled studies comparing awake craniotomy versus general anesthetic resection and reporting the language and neurological outcomes. Ten studies with 833 patients were included in the meta-analysis. The pooled risk ratio (RR) suggested no significant differences in language and neurological outcomes between general anesthesia group and awake craniotomy group without electrical stimulation. Awake craniotomy with electrical stimulation, however, was associated with improved late language and neurological outcomes (≥ 3 months) versus general anesthesia with pooled RR of 0.44 (95% CI = 0.20-0.96) and 0.49 (95% CI = 0.30-0.79), respectively. Awake craniotomy with electrical stimulation was also associated with better extent of resection with the pooled RR of 0.81 (95%CI = 0.71-0.92) and shorter hospital stay duration with the pooled weighted mean difference (WMD) of - 1.14 (95%CI = - 1.80 to - 0.48). This meta-analysis suggested that the application of awake craniotomy with electrical stimulation during glioma resection is associated with lower risks of long-term neurological and language deficits and higher extent of tumor resection, as well as shorter hospital stay duration.

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.

Optimizing the onco-functional balance in supratentorial brain tumour surgery: A single institution's initial experience with intraoperative cortico-subcortical mapping and monitoring in Singapore

Intraoperative cortical mapping provides functional information that permits the safe and maximal resection of supratentorial lesions infiltrating the so-called eloquent cortex or subcortical white matter tracts. Primary and secondary brain tumours located in eloquent cortex can render surgical treatment ineffective if it results in new or worsening neurology. A cohort of forty-six consecutive patients with supratentorial tumours of variable pathology involving eloquent cortical regions and aided with intraoperative neurophysiology were included for retrospective analysis at a single-centre tertiary institution. Intraoperative neurophysiological data has been related to immediate post-operative neurologic status as well as 3-month follow-up in patients that underwent awake or asleep surgical resection. Patients that experienced new or worsening neurologic symptoms post-operatively demonstrated a high incidence of recovery at 3-months. Those without new neurologic symptoms post-operatively demonstrated little to no worsening at 3-months. Our study explored the extent to which cortical mapping permitted safe surgical resection whilst preserving neurologic function. To the authors' knowledge this is the first documented case series in Singapore that has incorporated a systematic and individually tailored multimodal workflow to cortico-subcortical mapping and monitoring for the safe resection of infiltrative lesions of the supratentorial region.

Recent developments and future directions in adult lower-grade gliomas: Society for Neuro-Oncology (SNO) and European Association of Neuro-Oncology (EANO) consensus

The finding that most grades II and III gliomas harbor isocitrate dehydrogenase (IDH) mutations conveying a relatively favorable and fairly similar prognosis in both tumor grades highlights that these tumors represent a fundamentally different entity from IDH wild-type gliomas exemplified in most glioblastoma. Herein we review the most recent developments in molecular neuropathology leading to reclassification of these tumors based upon IDH and 1p/19q status, as well as the potential roles of methylation profiling and deletional analysis of cyclin-dependent kinase inhibitor 2A and 2B. We discuss the epidemiology, clinical manifestations, benefit of surgical resection, and neuroimaging features of lower-grade gliomas as they relate to molecular subtype, including advanced imaging techniques such as 2-hydroxyglutarate magnetic resonance spectroscopy and amino acid PET scanning. Recent, ongoing, and planned studies of radiation therapy and both cytotoxic and targeted chemotherapies are summarized, including both small molecule and immunotherapy approaches specifically targeting the mutant IDH protein.

Anesthetic considerations for awake craniotomy

Awake craniotomy is a gold standard of care for resection of brain tumors located within or close to the eloquent areas. Both asleep-awake-asleep technique and monitored anesthesia care have been used effectively for awake craniotomy and the choice of optimal anesthetic approach is primarily based on the preferences of the anesthesiologist and surgical team. Propofol, remifentanil, dexmedetomidine, and scalp nerve block provide the reliable conditions for intraoperative brain mapping. Appropriate patient selection, adequate perioperative psychological support, and proper anesthetic management for individual patients in each stage of surgery are crucial for procedural safety, success, and patient satisfaction.

Neuroanesthesia Practice During the COVID-19 Pandemic: Recommendations From Society for Neuroscience in Anesthesiology and Critical Care (SNACC)

The pandemic of coronavirus disease 2019 (COVID-19) has several implications relevant to neuroanesthesiologists, including neurological manifestations of the disease, impact of anesthesia provision for specific neurosurgical procedures and electroconvulsive therapy, and health care provider wellness. The Society for Neuroscience in Anesthesiology and Critical Care appointed a task force to provide timely, consensus-based expert guidance for neuroanesthesiologists during the COVID-19 pandemic. The aim of this document is to provide a focused overview of COVID-19 disease relevant to neuroanesthesia practice. This consensus statement provides information on the neurological manifestations of COVID-19, advice for neuroanesthesia clinical practice during emergent neurosurgery, interventional radiology (excluding endovascular treatment of acute ischemic stroke), transnasal neurosurgery, awake craniotomy and electroconvulsive therapy, as well as information about health care provider wellness. Institutions and health care providers are encouraged to adapt these recommendations to best suit local needs, considering existing practice standards and resource availability to ensure safety of patients and providers.

Awake vs. asleep motor mapping for glioma resection: a systematic review and meta-analysis

BACKGROUND

Intraoperative stimulation (IS) mapping has become the preferred standard treatment for eloquent tumors as it permits a more accurate identification of functional areas, allowing surgeons to achieve higher extents of resection (EOR) and decrease postoperative morbidity. For lesions adjacent to the perirolandic area and descending motor tracts, mapping can be done with both awake craniotomy (AC) and under general anesthesia (GA).

OBJECTIVE

We aimed to determine which anesthetic protocol-AC vs. GA-provides better patient outcomes by comparing EOR and postoperative morbidity for surgeries using IS mapping in gliomas located near or in motor areas of the brain.

METHODS

A systematic literature search was carried out to identify relevant studies from 1983 to 2019. Seven databases were screened. A total of 2351 glioma patients from 17 studies were analyzed.

RESULTS

A random-effects meta-analysis revealed a trend towards a higher mean EOR in AC [90.1% (95% C.I. 85.8-93.8)] than with GA [81.7% (95% C.I. 72.4-89.7)] (p = 0.06). Neurological deficits were divided by timing and severity for analysis. There was no significant difference in early neurological deficits [20.9% (95% C.I. 4.1-45.0) vs. 25.4% (95% C.I. 13.6-39.2)] (p = 0.74), late neurological deficits [17.1% (95% C.I. 0.0-50.0) vs. 3.8% (95% C.I. 1.1-7.6)] (p = 0.06), or in non-severe [28.4% (95% C.I. 0.0-88.5) vs. 20.1% (95% C.I. 7.1-32.2)] (p = 0.72), and severe morbidity [2.6% (95% C.I. 0.0-15.5) vs. 4.5% (95% C.I. 1.1-9.6)] (p = 0.89) between patients who underwent AC versus GA, respectively.

CONCLUSION

Mapping during resection of gliomas located in or near the perirolandic area and descending motor tracts can be safely carried out with both AC and GA.

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.

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.

Awake brain surgery in children-a single-center experience

INTRODUCTION

Awake brain surgery (ABS) represents a rare surgical procedure in children as age and psychological aspects, which are considered to interfere with its feasibility and psychological outcome and limit its application. Only few pediatric case series have been reported so far, indicating a more complex translation of this surgical approach to children. However, the advances in neuropsychological testing and monitoring may have a substantial impact on ameliorating the eligibility of children undergoing awake procedures. This study addresses the condition of ABS in a pediatric cohort, focusing on its practicability and diversified outcome aspects.

METHODS

We performed a retrospective review and prospective outcome analysis of pediatric patients with CNS lesions undergoing ABS between 2005 and 2018, completed at the University of Lyon, France.

RESULTS

Eighteen children were considered for ABS with respect to the eloquent location of their CNS lesions documented in their pre-operative MRI. Seventeen of them underwent asleep-awake-asleep brain surgery. The cohort included 5 males and 12 females. The median age at surgery was 14.8 years, (range 9.4 to 17.6 years). Intraoperative testing included electrocortical stimulation while pursuing speech or motor activity. Most of the lesions were intrinsic tumors of glial origin. A complete tumor removal was achieved in 11 patients (65%). Post-operative neurological deficits were transiently observed in 2 patients, whereas severe psychological reactions occurred in 1 child. Persistent attention deficits were found in 2 patients. One patient experienced an infectious complication requiring antibiotic treatment. Two patients died during follow-up due to tumor progression. The mean duration of follow up was 22.2 months (range 3.4 to 46.8 months).

CONCLUSIONS

ABS was shown to be beneficial in terms of efficient tumor resection besides simultaneous preservation of neurological functions. Psychological preparation of the families and the children is essential to increase the number and age range of patients, who can benefit from this technique. Neuropsychological testing before and after surgery is essential to determine cognitive outcome, which can be altered in a minority of patients.

Awake craniotomy for gliomas involving motor-related areas: classification and function recovery

PURPOSE

Motor mapping with direct cortical stimulation (DCS) is useful for motor function preservation. Nevertheless, many patients still experience postoperative motor dysfunction after motor mapping. This study aimed to provide a classification of gliomas involved in motor-related areas to help understand which types of gliomas are prone to induce postoperative motor impairments.

METHODS

Sixty-four patients were retrospectively recruited. Based on tumor location, four types of gliomas were identified: (I) precentral gyrus; (II) premotor and/or supplementary motor areas but not invading pre-central gyrus; (III) adjacent to the posterior limb of the internal capsule; and (IV) other supra-tentorial area. The recovery of motor function was evaluated by muscle strength testing before surgery and 3 days, 7 days, 14 days, and 3 months after surgery.

RESULTS

Half of the patients experienced postoperative transient motor impairment within a week. Six patients suffered from permanent motor dysfunction, and four of them had type III glioma. Compared with types I and IV, patients with type III gliomas took more than three times as long to recover. Furthermore, patients with types I and II gliomas were more susceptible to preoperative epilepsy than those with types III and IV. There was no difference in postoperative seizure control between the four types.

CONCLUSIONS

Our classification of gliomas involving motor-related eloquent areas was useful for predicting postoperative motor functional prognosis in patients who underwent motor mapping with DCS. Even if no positive sites were detected, a conservative strategy of tumor resection is recommended in cases that gliomas located close to the posterior limb of the internal capsule.

Incidence and predicting factors of perioperative complications during monitored anesthesia care for awake craniotomy

STUDY OBJECTIVE

To assess incidence and predicting factors of awake craniotomy complications.

DESIGN

Retrospective cohort study.

SETTING

Operating room and Post Anesthesia Care unit.

PATIENTS

162 patients who underwent 188 awake craniotomy procedures for brain tumor, ASA I to III, with monitored anesthesia care.

MEASUREMENTS

We classified procedures in 3 groups: major event group, minor event group, and no event group. Major events were defined as respiratory failure requiring face mask or invasive ventilation; hemodynamic instability treated by vasoactive drugs, or bradycardia treated by atropine, bleeding >500 ml, transfusion, gaseous embolism, cardiac arrest; seizure, cerebral edema, or any events leading to stopping of the cerebral mapping. Minor event was defined as any complication not classified as major. Multivariate logistic regression was used to determine predicting factors of major complication, adjusted for age and ASA score.

MAIN RESULTS

45 procedures (24%) were classified in major event group, 126 (67%) in minor event group, and 17 (9%) in no event group. Seizure was the main complication (n = 13). Asthma (odds ratio: 10.85 [1.34; 235.6]), Remifentanil infusion (odds ratio: 2.97 [1.08; 9.85]) and length of the operation after the brain mapping (odds ratio per supplementary minute: 1.01 [1.01; 1.03]) were associated with major events.

CONCLUSIONS

Previous medical history of asthma, remifentanil infusion and a long duration of neurosurgery after cortical mapping appear to be risk factors for major complications during AC.

A new simple brain segmentation method for extracerebral intracranial tumors

Normal brain segmentation is available via FreeSurfer, Vbm, and Ibaspm software. However, these software packages cannot perform segmentation of the brain for patients with brain tumors. As we know, damage from extracerebral tumors to the brain occurs mainly by way of pushing and compressing while leaving the structure of the brain intact. Three-dimensional (3D) imaging, augmented reality (AR), and virtual reality (VR) technology have begun to be applied in clinical practice. The free medical open-source software 3D Slicer allows us to perform 3D simulations on a computer and requires little user interaction. Moreover, 3D Slicer can integrate with the third-party software mentioned above. The relationship between the tumor and surrounding brain tissue can be judged, but accurate brain segmentation cannot be performed using 3D Slicer. In this study, we combine 3D Slicer and FreeSurfer to provide a novel brain segmentation method for extracerebral tumors. This method can help surgeons identify the “real” relationship between the lesion and adjacent brain tissue before surgery and improve preoperative planning.

Awake glioma surgery: technical evolution and nuances

INTRODUCTION

Multiple studies have demonstrated that improved extent of resection is associated with longer overall survival for patients with both high and low grade glioma. Awake craniotomy was developed as a technique for maximizing resection whilst preserving neurological function.

METHODS

We performed a comprehensive review of the literature describing the history, indications, techniques and outcomes of awake craniotomy for patients with glioma.

RESULTS

The technique of awake craniotomy evolved to become an essential tool for resection of glioma. Many perceived contraindications can now be managed. We describe in detail our preferred technique, the testing paradigms utilized, and critically review the literature regarding functional and oncological outcome.

CONCLUSIONS

Awake craniotomy with mapping has become the gold standard for safely maximizing extent of resection for tumor in or near eloquent brain. Cortical and subcortical mapping methods have been refined and the technique is associated with an extremely low rate of complications.

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.

Anesthesia and brain tumor surgery: technical considerations based on current research evidence

PURPOSE OF REVIEW

Anesthetics may influence cancer recurrence and metastasis following surgery by modulating the neuroendocrine stress response or by directly affecting cancer cell biology. This review summarizes the current evidence on whether commonly used anesthetics potentially affect postoperative outcomes following solid organ cancer surgery with particular focus on neurological malignancies.

RECENT FINDINGS

Despite significant improvement in diagnostic and therapeutic technology over the past decades, mortality rates after cancer surgery (including brain tumor resection) remains high. With regards to brain tumors, interaction between microglia/macrophages and tumor cells by multiple biological factors play an important role in tumor progression and metastasis. Preclinical studies have demonstrated an association between anesthetics and brain tumor cell biology, and a potential effect on tumor progression and metastasis has been revealed. However, in the clinical setting, the current evidence is inadequate to draw firm conclusions on the optimal anesthetic technique for brain tumor surgery.

SUMMARY

Further work at both the basic science and clinical level is urgently needed to evaluate the association between perioperative factors, including anesthetics/technique, and postoperative brain tumor outcomes.

The prognostic value of peri-operative neurological performance in glioblastoma patients

BACKGROUND

IDH-wild-type glioblastoma (GBM) is a disease with devastating prognosis. First-line therapy consists of gross total resection and adjuvant radiotherapy with concomitant temozolomide. Several clinical parameters have been identified to provide prognostic value. We investigated whether peri-operative overall neurological performance could also be used to evaluate patients' prognosis.

METHODS

All patients with histologically diagnosed GBM between 2014 and 2017 over 18 years and MRI within 72 h after surgery were reviewed. To quantify neurological performance, the medical research council neurological performance score (MRC-NPS) was used. 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 thirty-nine patients were included. In univariate analysis, survival decreased with increasing post-operative MRC-NPS scale. Moreover, post-operative MRC-NPS of 4 was statistically significant associated with reduced overall survival when analyzed for complete (p = 0.027) and partial resection (p = 0.002) as well as unilobar (p = 0.003) and multilobar tumor location (p < 0.0005). In multivariate analysis, extent of resection (hazard ratio (HR) 3.142), adjuvant therapy regimen (HR 3.001), tumor location (HR 2.005), and post-operative MRC-NPS (HR 2.310) had significant influence on overall survival.

CONCLUSION

We propose the post-operative neurological performance as an independent prognostic factor for GBM patients.

Development and implementation of a novel child life protocol to enhance psychosocial support for pediatric awake craniotomies: technical note

Awake craniotomies are a crucial tool for identifying eloquent cortex, but significant limitations frequently related to patient tolerance have limited their applicability in pediatric cases. The authors describe a comprehensive, longitudinal protocol developed in collaboration with a certified child life specialist (CCLS) in order to enhance patient experiences and develop resiliency related to the intraoperative portion of cases. This protocol includes preoperative conditioning, intraoperative support, and postoperative positive reinforcement and debriefing. A unique coping plan is developed for each prospective patient. With appropriate support, awake craniotomy may be applicable in a wider array of preadolescent and adolescent patients than has previously been possible. Future prospective studies are needed to validate this approach.

The challenge of overcoming the language barrier for brain tumor awake surgery in migrants: a feasibility study in five patient cases

OBJECTIVE

To assess the feasibility of awake surgery for a brain tumor in a population of non-French-speaking migrants in Paris, France.

METHODS

The Lariboisière database of awake surgeries was retrospectively reviewed, from the first case in 2011 up to July 2018. Inclusion criteria were patients being migrated in France during their adulthood, patients being unable to speak neither French nor English. Clinical and radiological data were collected from the electronic medical charts.

RESULTS

Five patients fulfilled inclusion criteria. Pathological diagnosis included three glioma, one meningioma, and one melanoma metastasis. The standard awake protocol of our center was followed as usual, with the additional involvement of an interpreter at each step. In the five cases, the awake procedure allowed the surgeon to tailor the resection according to functional boundaries. Resections were complete in three cases and subtotal in two cases. No neurological deficits were observed. All patients returned to their preoperative socio-professional status.

CONCLUSIONS

Awake surgery for a brain tumor can be offered to migrants, in spite of the poor verbal communication between the patient and the caring staff. A team dedicated to awake surgery and including an interpreter is the key to successfully overcome the language barrier, before, during, and after the surgery.

Following the light in glioma surgery: a comparison of sodium fluorescein and 5-aminolevulinic acid as surgical adjuncts in glioma resection

Gliomas are molecularly complex neoplasms and require a multidisciplinary approach to treatment. Maximal safe resection is often the initial goal of treatment and extent of resection (EOR) is an important prognostic factor correlating with both progression-free-survival (PFS) and overall survival (OS). Postoperative patient outcome is also a critical and independent prognosticator and high EOR must not be achieved at the expense of good functional outcome. Several intraoperative adjuvant techniques have been developed to help the surgeon push the boundaries of EOR while maintaining safety. Fluorescence-guided surgery for brain tumors is a contemporary adjuvant technique that allows for intraoperative delineation of diseased and normal brain thus improving maximal safe resection. The most extensively used fluorophores are 5-aminolevulinic acid (5-ALA) and sodium fluorescein (SFL). These fluorophores have different spectrophotometric properties, mechanisms of action and considerations for use. Both have demonstrated utility in neurosurgical oncology. They are safe and both are FDA approved for use as surgical adjuncts during resection of primary CNS neoplasms although they have been used with varying success for other tumor types. When combined with other surgical adjuvant strategies such as neuronavigation, intraoperative ultrasound, intraoperative MRI, awake resection and/or electrophysiological mapping/monitoring, fluorescence-guided resection appears to further improve resection quality in regard to EOR and safety. In this article, we review the current knowledge related to both fluorophores for brain tumor resection, their benefits, and pitfalls, as well as the major advantages associated with their use. We also briefly review additional fluorophores in early clinical development. Fluorescence-guided surgery is a novel surgical adjuvant which allows for real-time delineation of neoplastic tissues. The most widely used fluorophores are 5-ALA and SFL. They are safe compounds and there is a large body of evidence suggesting improvement in EOR when these are employed. There are nuances to the use of each; the fluorescence intensity is dose-dependent in either case and the sensitivity and specificity for various tumors vary widely. Additional prospective studies will be necessary to parse the impact of this technique and these fluorophores on survival metrics.

Stimulation-related intraoperative seizures during awake surgery: a review of available evidences

Awake surgery is a well-defined procedure with a very low morbidity. In particular, stimulation-related intraoperative seizure (IOS) is a commonly discussed and serious complication associated with awake surgery. Here, we reviewed the literature on awake surgery and IOS and sought to obtain evidences on the predictive factors of IOS and on the effect of IOS on postoperative outcomes. We conducted a comprehensive search of the Embase, MEDLINE, and Cochrane Central Register of Controlled Trials databases to identify potentially relevant articles from 2000 to 2019. We used combinations of the following search terms: "intraoperative seizure awake craniotomy," "awake surgery seizures," and pertinent associations; the search was restricted to publications in English and only to papers published in the last 20 years. The search returned 141 articles, including 39 papers that reported the IOS rate during awake craniotomy. The reported IOS rates ranged between 0 and 24% (mean, 7.7%). Only few studies have assessed the relationships between awake surgery and IOS, and hence, drawing clear conclusions is difficult. Nevertheless, IOS does not cause permanent and severe postoperative deficits, but can affect the patient's status perioperatively and the hospitalization duration. Anterior tumor location is an important perioperative factor associated with high IOS risk, whereas having seizures at tumor diagnosis does not seem to influence. However, the role of antiepileptic drug administration and prophylaxis remains unclear. In conclusion, given the difficulty in identifying predictors of IOS, we believe that prompt action at onset and awareness of appropriate management methods are vital.

Permutation entropy in intraoperative ECoG of brain tumour patients in awake tumour surgery- a robust parameter to separate consciousness from unconsciousness

Awake craniotomies represent an essential opportunity in the case of lesions in eloquent areas. Thus, optimal surveillance of the patient during different stages of sedation, as well as the detection of seizure activity during brain surgery, remains difficult, as skin electrodes for electroencephalographic (EEG) analysis are not applicable in most cases. We assessed the applicability of ECoG to monitor different stages of sedation, as well as the influence of different patient characteristics, such as tumour volume, size, entity, and age or gender on permutation entropy (PeEn). We conducted retrospective analysis of the ECoG data of 16 patients, who underwent awake craniotomies because of left-sided brain tumours at our centre between 2014 and 2016. PeEn could be easily calculated and compared using frontal and parietal cortical electrodes. A comparison of PeEn scores showed significantly higher values in awake patients than in patients under anaesthesia (p ≤ 0.004) and significantly higher ones in the state of transition than under general anaesthesia (p = 0.023). PeEn scores in frontal and parietal leads did not differ significantly, making them both applicable for continuous surveillance during brain surgery. None of the following clinical characteristics showed significant correlation with PeEn scores: tumour volume, WHO grade, first or recurrent tumour, gender, and sex. Being 50 years or older led to significantly lower values in parietal leads but not in frontal leads. ECoG and a consecutive analysis of PeEn are feasible and suitable for the continuous surveillance of patients during awake craniotomies. Hence, the analysis is not influenced by patients' clinical characteristics.

Awake brain surgery in children-review of the literature and state-of-the-art

OBJECTIVE

Awake brain surgery (ABS) is poorly reported in children as it is considered having limited indications due to age and neuropsychological aspects interfering with its feasibility and psychological outcome. The aim of this article is to review the current state-of-the-art of ABS in children and to offer an objective summary of the published literature on diversified outcome aspects of pediatric awake procedures.

METHODS

A literature review was performed using the MEDLINE (PubMed) electronic database applying the following MeSH terms to the keyword search within titles and abstracts: "awake brain surgery children," "awake brain surgery pediatric," "awake craniotomy children," "awake craniotomy pediatric," and "awake surgery children." Of the initial 753 results obtained from these keyword searches, a full text screening of 51 publications was performed, ultimately resulting in 18 eligible articles for this review.

RESULTS

A total of 18 full text articles reporting the results of 50 patients were included in the analysis. Sixteen of the 18 studies were retrospective studies, comprising 7 case series, 9 case reports, and 2 reviews. Eleven studies were conducted from anesthesiological (25 patients) and 7 from neurosurgical (25 patients) departments. Most of the patients underwent ABS for supratentorial lesions (26 patients), followed by epilepsy surgery (16 patients) and deep brain stimulation (DBS) (8 patients). The median age was 15 years (range 8-17 years). Persistent deficits occurred in 6 patients, (12%), corresponding to minor motor palsies (4%) and neuropsychological concerns (8%). An awake procedure was aborted in 2 patients (4%) due to cooperation failure and anxiety, respectively.

CONCLUSIONS

Despite well-documented beneficial aspects, ABS remains mainly limited to adults. This review confirms a reliable tolerability of ABS in selected children; however, recommendations and guidelines for its standardized implementation in this patient group are pending. Recommendations and guidelines may address diagnostic workup and intra-operative handling besides criteria of eligibility, psychological preparation, and coordinated neuropsychological testing in order to routinely offer ABS to children.

Carnosine increases efficiency of temozolomide and irradiation treatment of isocitrate dehydrogenase-wildtype glioblastoma cells in culture

Aim: The naturally occurring dipeptide carnosine (CAR) has been considered for glioblastoma therapy. As CAR also protects against ionizing irradiation (IR), we investigated whether it may counteract standard therapy consisting of postsurgery IR and treatment with temozolomide (TMZ). Materials & methods: Four isocitrate dehydrogenase-wildtype primary cell cultures were exposed to different doses of IR and different concentrations of TMZ and CAR. After exposure, viability under the different conditions and combinations of them was determined. Results: All cultures responded to treatment with TMZ and IR with reduced viability. CAR further decreased viability when TMZ and IR were combined. Conclusion: Treatment with CAR does not counteract glioblastoma standard therapy. As the dipeptide also protects nontumor cells from IR, it may reduce deleterious side effects of treatment.

The SAFE-trial: Safe surgery for glioblastoma multiforme: Awake craniotomy versus surgery under general anesthesia. Study protocol for a multicenter prospective randomized controlled trial

BACKGROUND

Surgery of GBM nowadays is usually performed under general anesthesia (GA) and resections are often not as aggressive as possible, due to the chance of seriously damaging the patient with a rather low life expectancy. A surgical technique optimizing resection of the tumor in eloquent areas but preventing neurological deficits is necessary to improve survival and quality of life in these patients. Awake craniotomy (AC) with the use of cortical and subcortical stimulation has been widely implemented for low-grade glioma resections (LGG), but not yet for GBM. AC has shown to increase resection percentage and preserve quality of life in LGG and could thus be of important value in GBM surgery.

METHODS/DESIGN

This study is a prospective, multicenter, randomized controlled trial (RCT). Consecutive patients with a glioblastoma in or near eloquent areas (Sawaya grading II/III) will be 1:1 randomized to awake craniotomy or craniotomy under general anesthesia. 246 patients will be included in neurosurgical centers in the Netherlands and Belgium. Primary end-points are: 1) Postoperative neurological morbidity and 2) Proportion of patients with gross-total resections. Secondary end-points are: 1) Health-related quality of life; 2) Progression-free survival (PFS); 3) Overall survival (OS) and 4) Frequency and severity of Serious Adverse Effects in each group. Also, a cost-benefit analysis will be performed. All patients will receive standard adjuvant treatment with concomitant chemoradiotherapy.

DISCUSSION

This RCT should demonstrate whether AC is superior to craniotomy under GA on neurological morbidity, extent of resection and survival for glioblastoma resections in or near eloquent areas.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT03861299 Netherlands Trial Register (NTR): NL7589.

Setup presentation and clinical outcome analysis of treating highly language-eloquent gliomas via preoperative navigated transcranial magnetic stimulation and tractography

OBJECTIVE Awake surgery combined with intraoperative direct electrical stimulation (DES) and intraoperative neuromonitoring (IONM) is considered the gold standard for the resection of highly language-eloquent brain tumors. Different modalities, such as functional magnetic resonance imaging (fMRI) or magnetoencephalography (MEG), are commonly added as adjuncts for preoperative language mapping but have been shown to have relevant limitations. Thus, this study presents a novel multimodal setup consisting of preoperative navigated transcranial magnetic stimulation (nTMS) and nTMS-based diffusion tensor imaging fiber tracking (DTI FT) as an adjunct to awake surgery. METHODS Sixty consecutive patients (63.3% men, mean age 47.6 ± 13.3 years) suffering from highly language-eloquent left-hemispheric low- or high-grade glioma underwent preoperative nTMS language mapping and nTMS-based DTI FT, followed by awake surgery for tumor resection. Both nTMS language mapping and DTI FT data were available for resection planning and intraoperative guidance. Clinical outcome parameters, including craniotomy size, extent of resection (EOR), language deficits at different time points, Karnofsky Performance Scale (KPS) score, duration of surgery, and inpatient stay, were assessed. RESULTS According to postoperative evaluation, 28.3% of patients showed tumor residuals, whereas new surgery-related permanent language deficits occurred in 8.3% of patients. KPS scores remained unchanged (median preoperative score 90, median follow-up score 90). CONCLUSIONS This is the first study to present a clinical outcome analysis of this very modern approach, which is increasingly applied in neurooncological centers worldwide. Although human language function is a highly complex and dynamic cortico-subcortical network, the presented approach offers excellent functional and oncological outcomes in patients undergoing surgery of lesions affecting this network.

Outpatient neurosurgery in neuro-oncology

Technological breakthroughs along with modern application of awake craniotomy and new neuroanesthesia protocols have led to a progressive development in outpatient brain tumor surgery and improved surgical outcomes. As a result, outpatient neurosurgery has become a standard of care at the authors' center due to its clinical benefits and impact on patient recovery and overall satisfaction. On the other hand, the financial savings derived from its application is also another favorable factor exerting influence on patients, health care systems, and society. Although validated several years ago and with recent data supporting its application, outpatient brain tumor surgery has not gained the traction that it deserves, based on scientific skepticism and perceived potential for medicolegal issues. The goal of this review, based on the available literature and the senior author's experience in outpatient brain tumor surgery, was to evaluate the most important aspects regarding indications, clinical outcomes, economic burden, and patient perceptions.

Risk factors for intraoperative stimulation-related seizures during awake surgery: an analysis of 109 consecutive patients

INTRODUCTION

During surgery for lesions in eloquent areas the goal is to achieve the widest resection possible, without loss of neurological function. Intraoperative seizures may lead to abandonment of the procedure or damages to the patient. Awareness regarding the predictors of IOS would help the surgeon. The aim of this retrospective study was to identify the factors associated with the occurrence of IOS in patients who underwent awake surgery for removal of gliomas in eloquent areas.

METHODS

This was a retrospective analysis of prospectively collected data of 109 patients who underwent awake craniotomy between January 2010 and December 2017 for removal of gliomas. IOS were defined as tonic-clonic seizures or loss of consciousness resulting in communication difficulties with the patient occurring during cortical and subcortical mapping.

RESULTS

A total of 109 patients were included in this study and IOS occurred in 9 (8.2%) patients. Demographic and clinical factors were comparable between patients with and without IOS. In the IOS group, 7 (77.8%) patients had seizures preoperatively and 4 (57.1%) were on more than one perioperative antiepileptic drugs (AED).

CONCLUSIONS

The current series add some hints to the poorly studied IOS risk during awake surgery. The risk of IOS appears to be relatively higher in patients with anteriorly located tumors and in patients operated without intraoperative brain activity monitoring and different patterns of stimulation for language and sensory-motor mapping. Further studies are needed to clarify the role of intraoperative techniques.

Intraoperative electrostimulation for awake brain mapping: how many positive interference responses are required for reliability?

OBJECTIVE

The purpose of this study was to characterize the reproducibility of language trials within and between brain mapping sessions.

METHODS

Brain mapping and baseline testing data from 200 adult patients who underwent resection of left-hemisphere tumors were evaluated. Data from 11 additional patients who underwent a second resection for recurrence were analyzed separately to investigate reproducibility over time. In all cases, a specific protocol of electrostimulation brain mapping with a controlled naming task was used to detect language areas, and the results were statistically compared with preoperative and intraoperative baseline naming error rates. All patients had normal preoperative error rates, controlled for educational level and age (mean 8.92%, range 0%-16.25%). Intraoperative baseline error rates within the normal range were highly correlated with preoperative ones (r = 0.74, p < 10-10), although intraoperative rates were usually higher (mean 13.30%, range 0%-26.67%). Initially, 3 electrostimulation trials were performed in each cortical area. If 2 of 3 trials showed language interference, 1 or 2 additional trials were performed (depending on results).

RESULTS

In the main group of 200 patients, there were 82 single interferences (i.e., positive results in 1 of 3 trials), 227 double interferences (2/3), and 312 full interferences (3/3). Binomial statistics revealed that full interferences were statistically significant (vs intraoperative baseline) in 92.7% of patients, while double interferences were significant only in 38.5% of patients, those with the lowest error rates. On further testing, one-third of the 2/3 trials became 2/4 trials, which was significant in only one-quarter of patients. Double interference could be considered significant for most patients (> 90%) when confirmed by 2 subsequent positive trials (4/5). In the 11 patients who were operated on twice, only 26% of areas that tested positive in the initial operation tested positive in the second and showed the same type of interference and the same current threshold (i.e., met all 3 criteria).

CONCLUSIONS

Electrostimulation trials in awake brain mapping produced graded patterns of positive reproducibility levels, and their significance varied with the baseline error rates. The results suggest that caution is warranted when 2 of 3 trials are positive, although the need for additional trials depends on the individual patients' baseline error rates. Reproducibility issues should be considered in the interpretation of data from awake brain mapping.

The Role of Extent of Resection in IDH1 Wild-Type or Mutant Low-Grade Gliomas

BACKGROUND

Maximizing extent of resection (EOR) improves outcomes in adults with World Health Organization (WHO) grade II low-grade gliomas (LGG). However, recent studies demonstrate that LGGs bearing a mutation in the isocitrate dehydrogenase 1 (IDH1) gene are a distinct molecular and clinical entity. It remains unclear whether maximizing EOR confers an equivalent clinical benefit in IDH mutated (mtIDH) and IDH wild-type (wtIDH) LGGs.

OBJECTIVE

To assess the impact of EOR on malignant progression-free survival (MPFS) and overall survival (OS) in mtIDH and wtIDH LGGs.

METHODS

We performed a retrospective review of 74 patients with WHO grade II gliomas and known IDH mutational status undergoing resection at a single institution. EOR was assessed with quantitative 3-dimensional volumetric analysis. The effect of predictor variables on MPFS and OS was analyzed with Cox regression models and the Kaplan-Meier method.

RESULTS

Fifty-two (70%) mtIDH patients and 22 (30%) wtIDH patients were included. Median preoperative tumor volume was 37.4 cm3; median EOR of 57.6% was achieved. Univariate Cox regression analysis confirmed EOR as a prognostic factor for the entire cohort. However, stratifying by IDH status demonstrates that greater EOR independently prolonged MPFS and OS for wtIDH patients (hazard ratio [HR] = 0.002 [95% confidence interval {CI} 0.000-0.074] and HR = 0.001 [95% CI 0.00-0.108], respectively), but not for mtIDH patients (HR = 0.84 [95% CI 0.17-4.13] and HR = 2.99 [95% CI 0.15-61.66], respectively).

CONCLUSION

Increasing EOR confers oncologic and survival benefits in IDH1 wtLGGs, but the impact on IDH1 mtLGGs requires further study.

The Stony Brook awake craniotomy protocol: A technical note

Most current awake craniotomy techniques utilize unnecessarily complicated airway management, and cause discomfort to the patients during the awake phase of the surgery. Our manuscript is written to discuss the neurosurgical and anesthetic techniques that we have developed to optimize awake craniotomy techniques at Stony Brook University Medical Center. We used the frameless Brainlab™ skull-mounted array for stereotactic navigation. Rigid fixation of the skull was avoided. General anesthesia with established airway was used during the "asleep" phase of the surgery. Following the removal of the bone flap and the opening of the dura, the patients were woken up, and the established airway was removed. Cortical mapping was performed to establish a safe entry zone for tumor removal. While the tumors were being removed, we continued motor examination and casual conversation with the patients to ensure safety. Patients were sedated during the remaining phase of the surgery until skin closure. No patient exhibited any neurological deficits or adverse anesthesia outcomes during the postoperative period. The protocol we developed avoids rigid skull fixation and emphasizes flexible intraoperative planning, thereby maximizing patient and physician comfort while allowing for successful tumor resection.

A 360° electronic device for recording high-resolution intraoperative electrocorticography of the brain during awake craniotomy

OBJECTIVE

Epilepsy is common among patients with supratentorial brain tumors; approximately 40%-70% of patients with glioma develop brain tumor-related epilepsy (BTRE). Intraoperative localization of the epileptogenic zone during surgical tumor resection (real-time data) may improve intervention techniques in patients with lesional epilepsy, including BTRE. Accurate localization of the epileptogenic signals requires electrodes with high-density spatial organization that must be placed on the cortical surface during surgery. The authors investigated a 360° high-density ring-shaped cortical electrode assembly device, called the "circular grid," that allows for simultaneous tumor resection and real-time electrophysiology data recording from the brain surface.

METHODS

The authors collected data from 99 patients who underwent awake craniotomy from January 2008 to December 2018 (29 patients with the circular grid and 70 patients with strip electrodes), of whom 50 patients were matched-pair analyzed (25 patients with the circular grid and 25 patients with strip electrodes). Multiple variables were then retrospectively assessed to determine if utilization of this device provides more accurate real-time data and improves patient outcomes.

RESULTS

Matched-pair analysis showed higher extent of resection (p = 0.03) and a shorter transient motor recovery period during the hospitalization course (by approximately 6.6 days, p ≤ 0.05) in the circular grid patients. Postoperative versus preoperative Karnofsky Performance Scale (KPS) score difference/drop was greater for the strip electrode patients (p = 0.007). No significant difference in postoperative seizures between the 2 groups was present (p = 0.80).

CONCLUSIONS

The circular grid is a safe, feasible tool that grants direct access to the cortical surgical surface for tissue resection while simultaneously monitoring electrical activity. Application of the circular grid to different brain pathologies may improve intraoperative epileptogenic detection accuracy and functional outcomes, while decreasing postoperative complications.

Subcortical stimulation mapping of descending motor pathways for perirolandic gliomas: assessment of morbidity and functional outcome in 702 cases

OBJECTIVE

Herein, the authors report their experience with intraoperative stimulation mapping to locate the descending subcortical motor pathways in patients undergoing surgery for hemispheric gliomas within or adjacent to the rolandic cortex, with particular description of the morbidity and functional outcomes associated with this technique.

METHODS

This is a retrospective analysis of patients who, in the period between 1997 and 2016, had undergone resection of hemispheric perirolandic gliomas within or adjacent to descending motor pathways. Data regarding intraoperative stimulation mapping and patient postoperative neurological status were collected.

RESULTS

Of 702 patients, stimulation mapping identified the descending motor pathways in 300 cases (43%). A new or worsened motor deficit was seen postoperatively in 210 cases (30%). Among these 210 cases, there was improvement in motor function to baseline levels by 3 months postoperatively in 161 cases (77%), whereas the deficit remained in 49 cases (23%). The majority (65%) of long-term deficits (persisting beyond 3 months) were mild or moderate (antigravity strength or better). On multivariate analysis, patients in whom the subcortical motor pathways had been identified with stimulation mapping during surgery were more likely to develop an additional and/or worsened motor deficit postoperatively than were those in whom the subcortical pathways had not been found (45% vs 19%, respectively, p < 0.001). This difference remained when considering the likelihood of a long-term deficit (i.e., persisting > 3 months; 12% vs 3.2%, p < 0.001). A higher tumor grade and the presence of a preoperative motor deficit were also associated with higher rates of motor deficits persisting long-term. A region of restricted diffusion adjacent to the resection cavity was seen in 20 patients with long-term deficits (41%) and was more common in cases in which the motor pathways were not identified (69%). Long-term deficits that occur in settings in which the subcortical motor pathways are not identified seem in large part due to ischemic injury to descending tracts.

CONCLUSIONS

Stimulation mapping allows surgeons to identify the descending motor pathways during resection of tumors in perirolandic regions and to attain an acceptable rate of morbidity in these high-risk cases.

Assessment of wakefulness during awake craniotomy to predict intraoperative language performance

OBJECTIVE

Maximal safe tumor resection in language areas of the brain relies on a patient's ability to perform intraoperative language tasks. Assessing the performance of these tasks during awake craniotomies allows the neurosurgeon to identify and preserve brain regions that are critical for language processing. However, receiving sedation and analgesia just prior to experiencing an awake craniotomy may reduce a patient's wakefulness, leading to transient language and/or cognitive impairments that do not completely subside before language testing begins. At present, the degree to which wakefulness influences intraoperative language task performance is unclear. Therefore, the authors sought to determine whether any of 5 brief measures of wakefulness predicts such performance during awake craniotomies for glioma resection.

METHODS

The authors recruited 21 patients with dominant hemisphere low- and high-grade gliomas. Each patient performed baseline wakefulness measures in addition to picture-naming and text-reading language tasks 24 hours before undergoing an awake craniotomy. The patients performed these same tasks again in the operating room following the cessation of anesthesia medications. The authors then conducted statistical analyses to investigate potential relationships between wakefulness measures and language task performance.

RESULTS

Relative to baseline, performance on 3 of the 4 objective wakefulness measures (rapid counting, button pressing, and vigilance) declined in the operating room. Moreover, these declines appeared in the complete absence of self-reported changes in arousal. Performance on language tasks similarly declined in the intraoperative setting, with patients experiencing greater declines in picture naming than in text reading. Finally, performance declines on rapid counting and vigilance wakefulness tasks predicted performance declines on the picture-naming task.

CONCLUSIONS

Current subjective methods for assessing wakefulness during awake craniotomies may be insufficient. The administration of objective measures of wakefulness just prior to language task administration may help to ensure that patients are ready for testing. It may also allow neurosurgeons to identify patients who are at risk for poor intraoperative performance.

Surgery of malignant motor-eloquent gliomas guided by sodium-fluorescein and navigated transcranial magnetic stimulation: a novel technique to increase the maximal safe resection

BACKGROUND

Maximal safe resection is the goal of modern surgical treatment of high-grade gliomas (HGGs) located close to the motor cortex (M1) and/or the corticospinal tract (CST). Preoperative planning based on navigated transcranial magnetic stimulation (nTMS) and fluorescence-guided resection (FGR) using sodium-fluorescein have been separately described to increase the extent of resection (EOR) while preserving the motor pathway. We assessed the efficacy of the combination of these techniques for surgery of motor-eloquent HGGs.

METHODS

We enrolled patients with motor-eloquent HGGs operated at the Departments of Neurosurgery of the University of Messina, Italy, and of the Charitè Universitatsmedizin Berlin, Germany, between 2016 and 2019. All patients underwent nTMS mapping of M1, and nTMS-based DTI tractography of CST. Tumor resection was guided by intraoperative neurophysiological mapping (IONM) supported by sodium-fluorescein fluorescence and by intraoperative visualization of the nTMS-based information through neuronavigation. EOR and new permanent motor deficits were compared with a historical control group of patients operated exclusively with IONM guidance.

RESULTS

Seventy-nine patients were enrolled, while 55 patients were included as controls. The gross total resection (GTR) rate was significantly higher in patients operated using nTMS + FGR compared with controls (64.5% vs. 47.2%, P=0.04). As well, postoperative new permanent motor deficits were reduced in the study group vs. controls (11.4% vs. 20%).

CONCLUSIONS

In this series, the combination of sodium-fluorescein FGR with nTMS-based planning improved surgical treatment of motor-eloquent HGGs. It represents a valuable support to IONM-guided resection, increasing the GTR rate while reducing the occurrence of permanent motor deficits.

Integrated datasets of normalized brain with functional localization using intra-operative electrical stimulation

PURPOSE

The purpose of this study was to transform brain mapping data into a digitized intra-operative MRI and integrated brain function dataset for predictive glioma surgery considering tumor resection volume, as well as the intra-operative and postoperative complication rates.

METHODS

Brain function data were transformed into digitized localizations on a normalized brain using a modified electric stimulus probe after brain mapping. This normalized brain image with functional information was then projected onto individual patient's brain images including predictive brain function data.

RESULTS

Log data were successfully acquired using a medical device integrated into intra-operative MR images, and digitized brain function was converted to a normalized brain data format in 13 cases. For the electrical stimulation positions in which patients showed speech arrest (SA), speech impairment (SI), motor and sensory responses during cortical mapping processes in awake craniotomy, the data were tagged, and the testing task and electric current for the stimulus were recorded. There were 13 SA, 7 SI, 8 motor and 4 sensory responses (32 responses) in total. After evaluation of transformation accuracy in 3 subjects, the first transformation from intra- to pre-operative MRI using non-rigid registration was calculated as 2.6 ± 1.5 and 2.1 ± 0.9 mm, examining neighboring sulci on the electro-stimulator position and the cortex surface near each tumor, respectively; the second transformation from pre-operative to normalized brain was 1.7 ± 0.8 and 1.4 ± 0.5 mm, respectively, representing acceptable accuracy.

CONCLUSION

This image integration and transformation method for brain normalization should facilitate practical intra-operative brain mapping. In the future, this method may be helpful for pre-operatively or intra-operatively predicting brain function.

Receptor tyrosine kinase gene amplification is predictive of intraoperative seizures during glioma resection with functional mapping

OBJECTIVE

Intraoperative seizures during craniotomy with functional mapping is a common complication that impedes optimal tumor resection and results in significant morbidity. The relationship between genetic mutations in gliomas and the incidence of intraoperative seizures has not been well characterized. Here, the authors performed a retrospective study of patients treated at their institution over the last 12 years to determine whether molecular data can be used to predict the incidence of this complication.

METHODS

The authors queried their institutional database for patients with brain tumors who underwent resection with intraoperative functional mapping between 2005 and 2017. Basic clinicopathological characteristics, including the status of the following genes, were recorded: IDH1/2, PIK3CA, BRAF, KRAS, AKT1, EGFR, PDGFRA, MET, MGMT, and 1p/19q. Relationships between gene alterations and intraoperative seizures were evaluated using chi-square and two-sample t-test univariate analysis. When considering multiple predictive factors, a logistic multivariate approach was taken.

RESULTS

Overall, 416 patients met criteria for inclusion; of these patients, 98 (24%) experienced an intraoperative seizure. Patients with a history of preoperative seizure and those treated with antiepileptic drugs prior to surgery were less likely to have intraoperative seizures (history: OR 0.61 [95% CI 0.38-0.96], chi-square = 4.65, p = 0.03; AED load: OR 0.46 [95% CI 0.26-0.80], chi-square = 7.64, p = 0.01). In a univariate analysis of genetic markers, amplification of genes encoding receptor tyrosine kinases (RTKs) was specifically identified as a positive predictor of seizures (OR 5.47 [95% CI 1.22-24.47], chi-square = 5.98, p = 0.01). In multivariate analyses considering RTK status, AED use, and either 2007 WHO tumor grade or modern 2016 WHO tumor groups, the authors found that amplification of the RTK proto-oncogene, MET, was most predictive of intraoperative seizure (p < 0.05).

CONCLUSIONS

This study describes a previously unreported association between genetic alterations in RTKs and the occurrence of intraoperative seizures during glioma resection with functional mapping. Future models estimating intraoperative seizure risk may be enhanced by inclusion of genetic criteria.

Predictors of Epileptic Seizures and Ability to Work in Supratentorial Cavernous Angioma Located Within Eloquent Brain Areas

BACKGROUND

The postoperative outcomes and the predictors of seizure control are poorly studied for supratentorial cavernous angiomas (CA) within or close to the eloquent brain area.

OBJECTIVE

To assess the predictors of preoperative seizure control, postoperative seizure control, and postoperative ability to work, and the safety of the surgery.

METHODS

Multicenter international retrospective cohort analysis of adult patients benefitting from a functional-based surgical resection with intraoperative functional brain mapping for a supratentorial CA within or close to eloquent brain areas.

RESULTS

A total of 109 patients (66.1% women; mean age 38.4 ± 12.5 yr), were studied. Age >38 yr (odds ratio [OR], 7.33; 95% confidence interval [CI], 1.53-35.19; P = .013) and time to surgery > 12 mo (OR, 18.21; 95% CI, 1.11-296.55; P = .042) are independent predictors of uncontrolled seizures at the time of surgery. Focal deficit (OR, 10.25; 95% CI, 3.16-33.28; P < .001) is an independent predictor of inability to work at the time of surgery. History of epileptic seizures at the time of surgery (OR, 7.61; 95% CI, 1.67-85.42; P = .003) and partial resection of the CA and/or of the hemosiderin rim (OR, 12.02; 95% CI, 3.01-48.13; P < .001) are independent predictors of uncontrolled seizures postoperatively. Inability to work at the time of surgery (OR, 19.54; 95% CI, 1.90-425.48; P = .050), Karnofsky Performance Status ≤ 70 (OR, 51.20; 95% CI, 1.20-2175.37; P = .039), uncontrolled seizures postoperatively (OR, 105.33; 95% CI, 4.32-2566.27; P = .004), and worsening of cognitive functions postoperatively (OR, 13.71; 95% CI, 1.06-176.66; P = .045) are independent predictors of inability to work postoperatively.

CONCLUSION

The functional-based resection using intraoperative functional brain mapping allows safe resection of CA and the peripheral hemosiderin rim located within or close to eloquent brain areas.

Determination of optimal time window for cortical mapping in awake craniotomy: assessment of intraoperative reaction speed

Currently, there is no known time frame when the patients are the most responsive during awake craniotomy. The aim of this work is therefore to determine when the patient has the shortest reaction time and so to extrapolate the optimal time window for cortical mapping. In this analytic observational study, our group has recorded the reaction times of 35 patients undergoing an awake craniotomy and compared them with the preoperative baseline. The operations were performed according to a "sleep-awake-awake" protocol. Data collection was performed in parallel with standard methods for evaluation of language and cognitive functions. The preoperative reaction times of our patient cohort (average ± SD = 510 ± 124 ms) were significantly shorter than those measured during the operation 786 ± 280 ms, p < .001. A one-factor ANOVA within subjects showed a significant increase in reaction times; p < .001. Post hoc comparisons on a Bonferroni-corrected α-error level of .05 showed significant differences between the reaction speed during the 0-10 min time frame and the preoperative baseline, as well as the intraoperative reaction times during the 20-30 min, 30-40 min, and the t > 40 min time frames. In conclusion, measurement of intraoperative reaction speed seems to be a technically feasible method that is well tolerated by the patients. The intraoperative reaction speed performance was shown to be significantly slower than on the day before the operation. The patients seem to be the slowest directly after extubation and gradually wake up during the awake phase. The poorest wakefulness is demonstrated during the first 20 min after extubation.