Low Rate of Intraoperative Seizures During Awake Craniotomy in a Prospective Cohort with 374 Supratentorial Brain Lesions: Electrocorticography Is Not Mandatory

Perioperative seizure in patients undergoing brain mapping under awake craniotomy for language-related eloquent region gliomas: a prospective study

BACKGROUND

Awake craniotomy (AC) is standard of care for lesions of eloquent brain areas. One important complication during AC is occurrence of intraoperative seizure (IOS), reported to occur among 3.4-20% of the patients. In this study, we report our experience with IOS during AC for resection of gliomas of the language eloquent regions and evaluate the predisposing factors and consequences.

METHODS

Patients who underwent AC for language related regions of the dominant hemisphere from August 2018 to June 2021 were enrolled. The rate of IOS during AC and relationship between predisposing factors and IOS were evaluated.

RESULTS

Sixty-five patients were enrolled (mean age: 44.4±12.5 years). Among 6 patients with IOS (9.2%), only one needed conversion to general anesthesia (GA) due to repeated seizures; while in the remaining 5, AC accomplished successfully despite one seizure attack in the awake phase. Tumor location (especially premotor cortex lesions, P=0.02, uOR:12.0, CI: 1.20-119.91), higher tumor volume (P=0.008, uOR: 1.9, CI: 1.06-1.12) and a functional tumor margin during surgery (P=0.000, uOR: 3.4, CI: 1.47-12.35) were significantly linked with IOS.

CONCLUSIONS

Occurrence of IOS was associated with a longer ICU stay after surgery and worse immediate neurological outcome, but had no impact on the late neurological status. IOS can usually be managed during AC without need to converting to GA. Those with larger tumors, frontal premotor lesions and positive brain mapping are susceptible to IOS. Early neurological deterioration observed after IOS, seems to be transient with no major long-term consequence on the neurological outcome.

Early Postoperative Seizures Following Awake Craniotomy and Functional Brain Mapping for Lesionectomy

OBJECTIVE

Awake craniotomy with electrocorticography (ECoG) and direct electrical stimulation (DES) facilitates lesionectomy while avoiding adverse effects. Early postoperative seizures (EPS), occurring within 7 days following surgery, can lead to morbidity. However, risk factors for EPS after awake craniotomy including clinical and ECoG data are not well defined.

METHODS

We retrospectively studied the incidence and risk factors of EPS following awake craniotomy for lesionectomy, and report short-term outcomes between January 1, 2020, and December 31, 2022.

RESULTS

We included 138 patients (56 female) who underwent 142 awake craniotomies, average age was 50.78 ± 15.97 years. Eighty-eight (63.7%) patients had a preoperative history of tumor-related epilepsy treated with antiseizure medication (ASM), 12 (13.6%) with drug-resistance. All others (36.3%) received ASM prophylaxis with levetiracetam perioperatively and continued for 14 days. An equal number of cases (71) each utilized a novel circle grid or strip electrodes for ECoG. There were 31 (21.8%) cases of intraoperative seizures, 16 with EPS (11.3%). Acute abnormality on early postoperative neuroimaging (P = 0.01), subarachnoid hemorrhage (P = 0.01), young age (P = 0.01), and persistent postoperative neurologic deficits (P = 0.013) were associated with EPS. Acute abnormality on neuroimaging remained significant in multivariate analysis. Outcomes during hospitalization and early outpatient follow up were worse with EPS.

CONCLUSIONS

We report novel findings using ECoG and clinical features to predict EPS, including acute perioperative brain injury, persistent postoperative deficits and young age. Given worse outcomes with EPS, clinical indicators for EPS should alert clinicians of potential need for early postoperative EEG monitoring and perioperative ASM adjustment.

Can we improve electrocorticography using a circular grid array in brain tumor surgery?

Intraoperative electrocorticography (iECoG) is used as an adjunct to localize the epileptogenic zone during surgical resection of brain tumors in patients with focal epilepsies. It also enables monitoring of after-discharges and seizures with EEG during functional brain mapping with electrical stimulation. When seizures or after-discharges are present, they complicate accurate interpretation of the mapping strategy to outline the brain's eloquent function and can affect the surgical procedure. Recurrent seizures during surgery requires urgent treatment and, when occurring during awake craniotomy, often leads to premature termination of brain mapping due to post-ictal confusion or sedation from acute rescue therapy. There are mixed results in studies on efficacy with iECoG in patients with epilepsy and brain tumors influencing survival and functional outcomes following surgery. Commercially available electrode arrays have inherent limitations. These could be improved with customization potentially leading to greater precision in safe and maximal resection of brain tumors. Few studies have assessed customized electrode grid designs as an alternative to commercially available products. Higher density electrode grids with intercontact distances less than 1 cm improve spatial delineation of electrophysiologic sources, including epileptiform activity, electrographic seizures, and afterdischarges on iECoG during functional brain mapping. In response to the shortcomings of current iECoG grid technologies, we designed and developed a novel higher-density hollow circular electrode grid array. The 360-degree iECoG monitoring capability allows continuous EEG recording during surgical intervention through the aperture with and without electrical stimulation mapping. Compared with linear strip electrodes that are commonly used for iECoG during surgery, the circular grid demonstrates significant benefits in brain tumor surgery. This includes quicker recovery of post-operative motor deficits (2.4 days versus 9 days, p = 0.05), more extensive tumor resection (92.0% versus 77.6%, p = 0.003), lesser reduction in Karnofsky Performance scale postoperatively (-2 versus -11.6, p = 0.007), and more sensitivity to recording afterdischarges. In this narrative review, we discuss the advantages and disadvantages of commercially available recording devices in the operating room and focus on the usefulness of the higher-density circular grid.

A Preoperative Scoring System to Predict Function-Based Resection Limitation Due to Insufficient Participation During Awake Surgery

BACKGROUND

Failure in achieving a function-based resection related to the insufficient patient's participation is a drawback of awake surgery.

OBJECTIVE

To assess preoperative parameters predicting the risk of patient insufficient intraoperative cooperation leading to the arrest of the awake resection.

METHODS

Observational, retrospective, multicentric cohort analysis enrolling 384 (experimental dataset) and 100 (external validation dataset) awake surgeries.

RESULTS

In the experimental data set, an insufficient intraoperative cooperation occurred in 20/384 patients (5.2%), leading to awake surgery failure in 3/384 patients (ie, no resection, 0.8%), and precluded the achievement of the function-based resection in 17/384 patients (ie, resection limitation, 4.4%). The insufficient intraoperative cooperation significantly reduced the resection rates (55.0% vs 94.0%, P < .001) and precluded a supratotal resection (0% vs 11.3%, P = .017). Seventy years or older, uncontrolled epileptic seizures, previous oncological treatment, hyperperfusion on MRI, and mass effect on midline were independent predictors of insufficient cooperation during awake surgery ( P < .05). An Awake Surgery Insufficient Cooperation score was then assessed: 96.9% of patients (n = 343/354) with a score ≤2 presented a good intraoperative cooperation, while only 70.0% of patients (n = 21/30) with a score >2 presented a good intraoperative cooperation. In the experimental data set, similar date were found: 98.9% of patients (n = 98/99) with a score ≤2 presented a good cooperation, while 0% of patients (n = 0/1) with a score >2 presented a good cooperation.

CONCLUSION

Function-based resection under awake conditions can be safely performed with a low rate of insufficient patient intraoperative cooperation. The risk can be assessed preoperatively by a careful patient selection.

Intraoperative Seizures During Awake Craniotomy for Brain Tumor Resection

Background Intra-operative seizures (IOS) can occur during awake craniotomies (AC) for brain tumors. They can potentially result in an increased risk of morbidity; however, literature is scarce on IOS, its risk factors, and predictors. This study aims to ascertain the frequency of IOS in patients undergoing AC and determine possible IOS predictors. Methods In this retrospective study, we reviewed the records of all patients who underwent AC for tumor resection at a single university hospital between January 2016 and December 2020. IOS was defined as any seizure, including partial or generalized, experienced by any patient at any time from the beginning of the procedure till the end of surgery. Results Two hundred patients underwent AC during the study period. Seven (3.5%) patients experienced IOS. Compared to the non-seizure group, no significant correlation existed with any demographic variable. No significant difference was seen between the initial complaints presented by the two groups. In addition, the post-operative course of the seizure group did not significantly differ from the non-seizure group. Due to the low frequency of IOS in our cohort, an extensive analysis to determine predictors could not be performed. Conclusion In this study, we observed a low frequency of IOS (3.5%) during AC. The possible predictors and risk factors must be further investigated in large cohorts; to help limit the consequences of this possible intraoperative complication.

Risk factors and predictors of intraoperative seizures during awake craniotomy: A systematic review and meta-analysis

Background

Awake craniotomy (AC) aims to minimize postoperative neurological complications while allowing maximum safe resection. Intraoperative seizures (IOSs) have been a reported complication during AC; however, literature delving into the predictors of IOS remains limited. Therefore, we planned a systematic review and meta-analysis of existing literature to explore predictors of IOS during AC.

Methods

From the inception until June 1, 2022, systematic searches of PubMed, Scopus, the Cochrane Library, CINAHL, and Cochrane's Central Register of Controlled Trials were conducted to look for published studies reporting IOS predictors during AC.

Results

We found 83 different studies in total; included were six studies with a total of 1815 patients, and 8.4% of them experienced IOSs. The mean age of included patients was 45.3 years, and 38% of the sample was female. Glioma was the most common diagnosis among the patients. A pooled random effect odds ratio (OR) of frontal lobe lesions was 2.42 (95% confidence intervals [CI]: 1.10-5.33, P = 0.03). Those with a pre-existing history of seizures had an OR of 1.80 (95% CI: 1.13-2.87, P = 0.01), and patients on antiepileptic drugs (AEDs) had a pooled OR of 2.47 (95% CI: 1.59-3.85, P < 0.001).

Conclusion

Patients with lesions of the frontal lobe, a prior history of seizures, and patients on AEDs are at higher risk of IOSs. These factors should be taken into consideration during the patient's preparation for an AC to avoid an intractable seizure and consequently a failed AC.

Risk Factors and Characteristics of Intraoperative Seizures During Awake Craniotomy: A Retrospective Cohort Study of 562 Consecutive Patients With a Space-occupying Brain Lesion

INTRODUCTION

Intraoperative seizures (IOSs) during awake craniotomy (AC) are associated with significant morbidity. The reported incidence of IOS is between 3% and 30%. The aim of this study was to identify risk factors for IOS during AC for elective resection or biopsy of a space-occupying brain lesion.

METHODS

In this retrospective study, we reviewed the records of all awake craniotomies performed by a single neurosurgeon at a single university hospital between July 2006 and December 2018. IOS was defined as a clinically apparent seizure that occurred in the operating room and was documented in the medical records. Explanatory variables were chosen based on previously published literature on risk factors for IOS.

RESULTS

Five hundred and sixty-two patients had a total of 607 AC procedures during the study period; 581 cases with complete anesthesia records were included in analysis. Twenty-nine (5.0%) IOS events were reported during 29 (5%) awake craniotomies. Most seizures (27/29; 93%) were focal in nature and did not limit planned intraoperative stimulation mapping. Variables associated with IOS at a univariate P -value <0.1 (frontal location of tumor, preoperative radiotherapy, preoperative use of antiepileptic drugs, intraoperative use of dexmedetomidine, and intraoperative stimulation mapping) were included in a multivariable logistic regression. Frontal location of tumor (adjusted odds ratio: 5.68, 95% confidence interval: 2.11-15.30) and intraoperative dexmedetomidine use (adjusted odds ratio: 2.724, 95% confidence interval: 1.24-6.00) were independently associated with IOS in the multivariable analysis.

CONCLUSIONS

This study identified a low incidence (5%) of IOS during AC. The association between dexmedetomidine and IOS should be further studied in randomized trials as this is a modifiable risk factor.

Effect of Dexmedetomidine versus Propofol on Intraoperative Seizure Onset During Awake Craniotomy: A Retrospective Study

OBJECTIVE

The effect of dexmedetomidine (DEX) compared with propofol on intraoperative seizures (IOSs) detected using electrocorticography during awake craniotomy for resection of brain tumors is unknown. This investigation aimed to compare IOS rate in patients receiving DEX versus propofol as sedative agent.

METHODS

In this retrospective single-center study, awake craniotomies performed from January 2014 to December 2019 were analyzed. All IOSs detected by electrocorticography along with vital signs were recorded.

RESULTS

Of 168 adults enrolled in the study, 58 were administered DEX and 110 were administered propofol. IOSs occurred more frequently in the DEX group (22%) versus the propofol group (11%) (P = 0.046). A higher incidence of bradycardia was also observed in the DEX group (P < 0.001). Higher incidence of hypertension and a higher mean heart rate were recorded in the propofol group (P = 0.006 and P < 0.001, respectively). No serious adverse events requiring active drug administration were noted in either group. At univariate regression analysis, DEX demonstrated a tendency to favor IOS onset but without statistical significance (odds ratio = 2.36, P = 0.051). Patients in both groups had a similar epilepsy outcome at the 1-year postoperative follow-up.

CONCLUSIONS

IOSs detected with electrocorticography during awake craniotomy occurred more frequently in patients receiving DEX than propofol. However, patients receiving DEX were not shown to be at a statistically significant greater risk for IOS onset. DEX is a valid alternative to propofol during awake craniotomy in patients affected by tumor-related epilepsy.

Multimodal mapping and monitoring is beneficial during awake craniotomy for intra-cranial tumours: results of a dual centre retrospective study

BACKGROUND

The combination of awake craniotomy with multimodal neurophysiological mapping and monitoring in intra-axial tumour resection is not well described, but may have theoretical benefits which we sought to investigate.

METHODS

All patients undergoing awake craniotomy for tumour resection with cortical and/or subcortical stimulation together with one or more of electrocorticography (ECoG/EEG), motor or somatosensory evoked potentials were identified from the operative records of two surgeons at two centres over a 5 year period. Patient, operative and outcome data were collated. Statistical analysis was performed to evaluate factors predictive of intra-operative seizures and surgical outcomes.

RESULTS

83 patients with a median age 50 years (18-80 years) were included. 80% had gliomas (37% low grade) and 13% metastases. Cortical mapping was negative in 35% (language areas) and 24% (motor areas). Complete or near total resection was achieved in 80% with 5% severe long-term neurological deficits. Negative cortical mapping was combined with positive subcortical mapping in 42% with no significant difference in extent of resection rates to patients undergoing positive cortical mapping (p = 0.95). Awake mapping could not be completed in 14%, but with no compromise to extent of resection (p = 0.55) or complication rates (p = 0.09). Intraoperative seizures occurred in 11% and were significantly associated with intra-operative EEG spikes (p = 0.003).

CONCLUSIONS

Awake multi-modal monitoring is a safe and well tolerated technique. It provides preservation of extent of resection and clinical outcomes in cases of aborted awake craniotomy. Negative cortical mapping in combination with positive subcortical mapping was also shown to be safe, although not hitherto well described. Electrocorticography further enables the differentiation of seizure activity from true positive mapping, and the successful treatment of spikes prior to full clinical seizures occurring.

Risk Factors for Intraoperative Seizures in Glioma Surgery: Electrocorticography Matters

PURPOSE

Few and contradictory data are available regarding intraoperative seizures during surgery for low-grade gliomas. Aim of this study was to evaluate possible risk factors for the occurrence of IOS.

METHODS

The authors performed a retrospective analysis of 155 patients affected by low-grade gliomas and tumor-related epilepsy, who underwent surgery in our Department, between 2007 and 2018. A statistical analysis was performed by means of univariate and multivariate regression to evaluate any possible correlation between seizure occurrence and several demographic, clinical, neurophysiological, and histopathological features.

RESULTS

Intraoperative seizure occurred in 39 patients (25.16%) with a total of 62 seizure events recorded. Focal seizures were the prevalent seizure type: among them, 39 seizures did not show motor signs, being those with only electrographic and/or with cognitive features the most represented subtypes. Twenty-six seizures occurring during surgery were not spontaneous: direct cortical stimulation with Penfield paradigm was the most prevalent evoking factor. The univariate analysis showed that the following prognostic factors were statistically associated with the occurrence of intraoperative seizure: the awake technique ( P = 0.01) and the interictal epileptiform discharges detected on the baseline electrocorticography (ECoG) ( P < 0.001). After controlling for confounding factors with multivariate analysis, the awake surgery and the epileptic ECoG pattern kept statistical significance.

CONCLUSIONS

The awake surgery procedure and the epileptic ECoG pattern are risk factors for intraoperative seizure. ECoG is mandatory to detect electrographic seizures or seizures without motor signs.

Diffusion tensor imaging, intra-operative neurophysiological monitoring and small craniotomy: Results in a consecutive series of 103 gliomas

Diffusion tensor imaging (DTI) allows visualization of the main white matter tracts while intraoperative neurophysiological monitoring (IONM) represents the gold standard for surgical resection of gliomas. In recent years, the use of small craniotomies has gained popularity thanks to neuronavigation and to the low morbidity rates associated with shorter surgical procedures. The aim of this study was to review a series of patients operated for glioma using DTI, IONM, and tumor-targeted craniotomies. The retrospective analysis included patients with supratentorial glioma who met the following inclusion criteria: preoperative DTI, intraoperative IONM, tumor-targeted craniotomy, pre- and postoperative MRI, and complete clinical charts. The DTI was performed on a 3T scanner. The IONM included electroencephalography (EEG), transcranial (TC) and/or cortical motor-evoked potentials (MEP), electrocorticography (ECoG), and direct electrical stimulation (DES). Outcomes included postoperative neurological deficits, volumetric extent of resection (EOR), and overall survival (OS). One hundred and three patients (61 men, 42 women; mean age 54 ± 14 years) were included and presented the following WHO histologies: 65 grade IV, 19 grade III, and 19 grade II gliomas. After 3 months, only three patients had new neurological deficits. The median postoperative volume was 0cc (IQR 3). The median OS for grade IV gliomas was 15 months, while for low-grade gliomas it was not reached. In our experience, a small craniotomy and a tumor resection supported by IONM and DTI permitted to achieve satisfactory results in terms of neurological outcomes, EOR, and OS for glioma patients.

Enhanced Recovery After Surgery (ERAS) for Cranial Tumor Resection: A Review

Enhanced Recovery After Surgery (ERAS) protocols describe a standardized method of preoperative, perioperative, and postoperative care to enhance outcomes and minimize complication risks surrounding elective surgical intervention. A growing body of evidence is being generated as we learn to apply principles of ERAS standardization to neurosurgical patients. First applied in spinal surgery, ERAS protocols have been extended to cranial neuro-oncological procedures. This review synthesizes recent findings to generate evidence-based guidelines to manage neurosurgical oncology patients with standardized systems and assess ability of these systems to coordinate multidisciplinary, patient-centric care efforts. Furthermore, we highlight the potential utility of multimedia, app-based communication platforms to facilitate patient education, autonomy, and team communication within each of the three settings.

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.

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.

The death of localizationism: The concepts of functional connectome and neuroplasticity deciphered by awake mapping, and their implications for best care of brain-damaged patients

Although clinical neurology was mainly erected on the dogma of localizationism, numerous reports have described functional recovery after lesions involving presumed non-compensable areas in an inflexible view of brain processing. Here, the purpose is to review new insights into the functional connectome and the mechanisms underpinning neural plasticity, gained from intraoperative direct electrostimulation mapping and real-time behavioral monitoring in awake patients, combined with perioperative neuropsychological and neuroimaging data. Such longitudinal anatomo-functional correlations resulted in the reappraisal of classical models of cognition, especially by highlighting the dynamic interplay within and between neural circuits, leading to the concept of meta-network (network of networks), as well as by emphasizing that subcortical connectivity is the main limitation of neuroplastic potential. Beyond their contribution to basic neurosciences, these findings might also be helpful for an optimization of care for brain-damaged patients, such as in resective oncological or epilepsy neurosurgery in structures traditionally deemed inoperable (e.g., in Broca's area) as well as for elaborating new programs of functional rehabilitation, eventually combined with transcranial brain stimulation, aiming to change the connectivity patterns in order to enhance cognitive competences following cerebral injury.

Anesthetic technique for awake artery malformation clipping with motor evoked potential and somatosensory evoked potential: A case report

BACKGROUND

Awake craniotomy has been widely used for tumor resection, epilepsy surgery, deep brain stimulation, and carotid endarterectomy. The report on awake artery malformation clipping is rare, especially for anesthesia management.

CASE SUMMARY

A 62-year-old female diagnosed with malformation of anterior cerebral artery at the right side. We clipped the artery malformation with intraoperative neuromonitoring (IONM) in awake craniotomy. Spontaneous respiration was maintained throughout the procedure by nasopharyngeal airway during the surgery successfully.

CONCLUSION

The technique of monitoring anesthesia care can be performed successfully for the patient with IONM.

Presence of a translator in the operating theater for awake mapping in foreign patients with low-grade glioma: a surgical experience based on 18 different native languages

OBJECTIVE

Intraoperative brain mapping with neurocognitive monitoring during awake surgery is currently the standard pattern of care for patients with diffuse low-grade glioma (DLGG), allowing a maximization of the extent of resection (EOR) while preserving quality of life. This study evaluated the feasibility of DLGG resections performed with intraoperative cognitive monitoring via the assistance of a translator for patients speaking foreign languages, and compared the surgical functional and oncological outcomes according to the possibility of direct communication with the surgical team.

METHODS

Foreign patients who underwent awake surgery with intraoperative electrical mapping with the assistance of a translator for the resection of a DLGG in the authors' institution between January 2010 and December 2020 were included. Patients whose native language included one of the three languages spoken by the surgical team (i.e., French, English, or Spanish) were excluded. The patients were classified into two groups. Group 1 was composed of patients able to communicate in at least one of these three languages in addition to their own native language. Group 2 was composed of patients who spoke none of these languages, and therefore were unable to communicate directly with the operating staff. The primary outcome was the patients' ability to return to work 3 months after surgery.

RESULTS

Eighty-four patients were included, of whom 63 were classified in group 1 and 21 in group 2. Eighteen different native languages were tested in the operating theater. Awake mapping was successful, with elicitation of transitory disturbances in all patients. There was no significant difference in the 3-month return-to-work status between the two groups (95% in group 1 [n = 58/61] vs 88% in group 2 [n = 15/17]; p = 0.298). Similarly, no significant difference between the two groups was found regarding the intraoperative tasks performed, the mean duration of the surgery, and the rate of permanent postoperative deficit. A significantly greater EOR was observed in group 1 patients in comparison to group 2 patients (90.4% ± 10.6% vs 87.7% ± 6.1%; p = 0.029).

CONCLUSIONS

Real-time translation by an interpreter during awake resection of glioma is feasible and safe in foreign patients. Nonetheless, when no direct verbal communication is possible between the surgical team and the patient, the EOR is less.

Feasibility, Safety and Impact on Overall Survival of Awake Resection for Newly Diagnosed Supratentorial IDH-Wildtype Glioblastomas in Adults

Simple Summary

A few studies have suggested the benefits of awake surgery by maximizing the extent of resection while preserving neurological function and improving survival in high-grade glioma patients. However, the histomolecular heterogeneity in these series, mixing grade 3 with grade 4, and IDH-mutated with IDH-wildtype gliomas, represents a major selection bias that may influence survival analyses. For the first time, in a large homogeneous single-institution cohort of newly diagnosed supratentorial IDH-wildtype glioblastoma in adult patients, we assessed feasibility, safety and efficacy of awake surgery using univariate, multivariate and case-matched analysis. Awake surgery was associated with higher resection rates, lower residual tumor rates, and more supratotal resections than asleep resections, allowed standard radiochemotherapy to be performed systematically within a short time between surgery and radiotherapy, and was an independent predictor of progression-free survival and overall survival in the whole series, together with the extent of resection, MGMT promoter methylation status, and standard.

Abstract

Background: Although awake resection using intraoperative cortico-subcortical functional brain mapping is the benchmark technique for diffuse gliomas within eloquent brain areas, it is still rarely proposed for IDH-wildtype glioblastomas. We have assessed the feasibility, safety, and efficacy of awake resection for IDH-wildtype glioblastomas. Methods: Observational single-institution cohort (2012–2018) of 453 adult patients harboring supratentorial IDH-wildtype glioblastomas who benefited from awake resection, from asleep resection, or from a biopsy. Case matching (1:1) criteria between the awake group and asleep group: gender, age, RTOG-RPA class, tumor side, location and volume and neurosurgeon experience. Results: In patients in the awake resection subgroup (n = 42), supratotal resections were more frequent (21.4% vs. 3.1%, p < 0.0001) while partial resections were less frequent (21.4% vs. 40.1%, p < 0.0001) compared to the asleep (n = 222) resection subgroup. In multivariable analyses, postoperative standard radiochemistry (aHR = 0.04, p < 0.0001), supratotal resection (aHR = 0.27, p = 0.0021), total resection (aHR = 0.43, p < 0.0001), KPS score > 70 (HR = 0.66, p = 0.0013), MGMT promoter methylation (HR = 0.55, p = 0.0031), and awake surgery (HR = 0.54, p = 0.0156) were independent predictors of overall survival. After case matching, a longer overall survival was found for awake resection (HR = 0.47, p = 0.0103). Conclusions: Awake resection is safe, allows larger resections than asleep surgery, and positively impacts overall survival of IDH-wildtype glioblastoma in selected adult patients.

Predictive Evolution Factors of Incidentally Discovered Suspected Low-Grade Gliomas: Results From a Consecutive Series of 101 Patients

BACKGROUND

Incidentally discovered suspected diffuse low-grade gliomas (LGGs) on brain imaging pose a challenge to neurosurgeons. Modern surgical series of LGGs favor early prophylactic surgery with a maximal extent of resection. However, some nonevolutive lesions may mimic LGGs on magnetic resonance imaging (MRI).

OBJECTIVE

To determine objective criteria to advocate surgical resection of an incidentally discovered suspected LGG based upon MRI findings.

METHODS

The prospective cohort of patients referred to our institution for an incidental finding suggestive of LGG was retrospectively reviewed. Stable lesions underwent systematic serial MRI follow-up, while evolutive lesions underwent prophylactic surgery under awake conditions. Initial clinico-radiological features were compared between stable and evolutive lesions in order to determine predictive criteria of further evolution.

RESULTS

Among 101 patients referred for surgical resection of incidentally discovered suspected LGG in our center, 19 patients (18.8%) had nonevolutive MRI lesions after a mean follow-up of 46.9 ± 34.9 mo. Insular topography (P = .003), higher mean volume at discovery (19.2 vs 5.2 cm3, P < .001), and adjacent sulcal effacement (P = .001) were associated with evolutive lesions. Histopathological diagnosis of LGG was confirmed in all surgical cases.

CONCLUSION

Increasing volume is an effective predictor of LGG diagnosis in incidental MRI findings, as all patients who subsequently underwent surgery had confirmed histopathological diagnosis of diffuse glioma. Approximately 18.8% of incidental findings were stable over time. Insular topography, adjacent sulcal effacement, and volume greater than 4.5 cm3 were predictive of further radiological progression. These significant elements will help neurosurgeons to define personalized strategies in this complex setting of incidental discovery.

Analysis of risk factors and clinical sequelae of direct electrical cortical stimulation-induced seizures and afterdischarges in patients undergoing awake mapping

OBJECTIVE

Intraoperative stimulation has emerged as a crucial adjunct in neurosurgical oncology, aiding maximal tumor resection while preserving sensorimotor and language function. Despite increasing use in clinical practice of this stimulation, there are limited data on both intraoperative seizure (IS) frequency and the presence of afterdischarges (ADs) in patients undergoing such procedures. The objective of this study was to determine risk factors for IS or ADs, and to determine the clinical consequences of these intraoperative events.

METHODS

A retrospective chart review was performed for patients undergoing awake craniotomy (both first time and repeat) at a single institution from 2013 to 2018. Hypothesized risk factors for ADs/ISs in patients were evaluated for their effect on ADs and ISs, including tumor location, tumor grade (I-IV), genetic markers (isocitrate dehydrogenase 1/2, O 6-methylguanine-DNA methyltransferase [MGMT] promoter methylation, chromosome 1p/19q codeletion), tumor volume, preoperative seizure status (yes/no), and dosage of preoperative antiepileptic drugs for each patient. Clinical outcomes assessed in patients with IS or ADs were duration of surgery, length of stay, presence of perioperative deficits, and postoperative seizures. Chi-square analysis was performed for binary categorical variables, and a Student t-test was used to assess continuous variables.

RESULTS

A total of 229 consecutive patients were included in the analysis. Thirty-five patients (15%) experienced ISs. Thirteen (37%) of these 35 patients had experienced seizures that were appreciated clinically and noted on electrocorticography simultaneously, while 8 patients (23%) experienced ISs that were electrographic alone (no obvious clinical change). MGMT promoter methylation was associated with an increased prevalence of ISs (OR 3.3, 95% CI 1.2-7.8, p = 0.02). Forty patients (18%) experienced ADs. Twenty-three percent of patients (9/40) with ISs had ADs prior to their seizure, although ISs and ADs were not statistically associated (p = 0.16). The presence of ADs appeared to be correlated with a shorter length of stay (5.1 ± 2.6 vs 6.1 ± 3.7 days, p = 0.037). Of the clinical features assessed, none were found to be predictive of ADs. Neither IS nor AD, or the presence of either IS or AD (65/229 patients), was a predictor for increased length of stay, presence of perioperative deficits, or postoperative seizures.

CONCLUSIONS

ISs and ADs, while commonly observed during intraoperative stimulation for brain mapping, do not negatively affect patient outcomes.

Disrupting self-evaluative processing with electrostimulation mapping during awake brain surgery

Brain awake surgery with cognitive monitoring for tumor removal has become a standard of treatment for functional purpose. Yet, little attention has been given to patients' interpretation and awareness of their own responses to selected cognitive tasks during direct electrostimulation (DES). We aim to report disruptions of self-evaluative processing evoked by DES during awake surgery. We further investigate cortico-subcortical structures involved in self-assessment process and report the use of an intraoperative self-assessment tool, the self-confidence index (SCI). Seventy-two patients who had undergone awake brain tumor resections were selected. Inclusion criteria were the occurrence of a DES-induced disruption of an ongoing task followed by patient's failure to remember or criticize these impairments, or a dissociation between patient's responses to an ongoing task and patient's SCI. Disruptions of self-evaluation were frequently associated with semantic disorders and critical sites were mostly found along the left/right ventral semantic streams. Disconnectome analyses generated from a tractography-based atlas confirmed the high probability of the inferior fronto-occipital fasciculus to be transitory 'disconnected'. These findings suggest that white matters pathways belonging to the ventral semantic stream may be critically involved in human self-evaluative processing. Finally, the authors discuss the implementation of the SCI task during multimodal intraoperative monitoring.

Awake Epilepsy Surgery in Patients with Focal Cortical Dysplasia

BACKGROUND

Awake craniotomy (AC) and direct electric stimulation emerged together with epilepsy surgery >80 years ago. The goal of our study was to evaluate the benefits of awake surgery in patients with drug-resistant epilepsy caused by focal cortical dysplasia (FCD) affecting eloquent areas.

METHODS

Our material included 95 patients with drug-resistant epilepsy and FCD, who were operated on between January 2009 and December 2018. These 95 patients were assigned into 3 groups: AC; general anesthesia (GA) with intraoperative neuromonitoring; and GA without intraoperative neuromonitoring. We investigated the following variables: age at surgery, lesion side, eloquent cortex involvement, brain mapping success rate, epilepsy surgery success rate, intraoperative complications, postoperative complications, and intraoperative changes of the preoperative resection plan according to results of the brain mapping by direct electric stimulation.

RESULTS

We found statistically significant differences between the AC and GA groups in the mean age at operation, lesion side, eloquent localization, and postoperative transient neurologic deficit. Seizure outcome in the AC was satisfactory (71% complete seizure control) and comparable to the seizure outcome in the GA groups. Our preoperative plan was changed because of functional constraints in 6 patients (43%) operated on during AC.

CONCLUSIONS

AC during epilepsy surgery for FCD in eloquent areas may change the preoperative plan. The good rate of postoperative seizure control and the absence of permanent postoperative neurologic deficit in our series is the main proof that AC is a useful tool in patients with FCD involving the eloquent cortex.

Intra- and postoperative adverse events in awake craniotomy for intrinsic supratentorial brain tumors

OBJECTIVE

To determine the frequency and consequences of intra- and postoperative adverse events in awake craniotomy for intrinsic supratentorial brain tumors. Despite the growing prevalence of awake craniotomy intra- and postoperative, adverse events related to this surgery are poorly discussed.

METHODS

We studied 25 patients undergoing awake craniotomy with maximum safe resection of intrinsic supratentorial brain tumors in the awake-asleep-awake protocol.

RESULTS

Surgery-related inconveniences occurred in 23 patients (92%), while postoperative adverse events were observed in 17 cases (68%). Seven patients suffered from more than one postoperative complication. The most common surgery-related inconvenience was intraoperative hypertension (8 cases, 32%), followed by discomfort (7 cases, 28%), pain during surgery (5 cases, 20%), and tachycardia (3 cases, 12%). The most common postoperative adverse event was a new language deficit that occurred in 10 cases (40%) and remained permanent in one case (4%). Motor deficits occurred in 36% of cases and were permanent in one case (1%). Seizures were observed in 4 cases (16%) intra- and in 2 cases (8%) postoperatively. Seizures appeared more frequently in patients with multilobar insular-involving gliomas and in patients without prophylactic antiepileptic drug therapy.

CONCLUSIONS

Surgery-related inconveniences and postoperative adverse events occur in most awake craniotomies. The most common intraoperative adverse event is hypertension, pain, and tachycardia. The most frequent postoperative adverse events are new language deficits and new motor deficits.

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.

Predictors of stimulation-induced seizures during perirolandic glioma resection using intraoperative mapping techniques

BACKGROUND

Intraoperative mapping techniques maximize safety and efficacy during perirolandic glioma resection but may induce seizures and limit the procedure. We aim to report the incidence and predictors of stimulation-induced seizures during mapping either patient is awake or under general anesthesia (GA).

METHODS

Retrospective analysis of 64 patients (40 awake and 24 GA) with perirolandic glioma underwent resection using intraoperative mapping techniques between 2014 and 2019. Preoperative data, operative details, postoperative neurological status, and extent of resection (EOR) were analyzed. Predictors of intraoperative seizures were assessed.

RESULTS

The mean cortical and subcortical stimulation intensities needed to evoke motor responses were significantly lower in awake cases than in GA patients (4.9 ± 0.42 vs. 8.9 ± 1.2 mA) and (8.3 ± 0.62 vs. 12.1 ± 1.1 mA), respectively (P = 0.01). Incidence of intraoperative seizures was lower but statistically non-significant in awake cases (10% vs. 12.5%) (P = 0.76). Preoperative multiple antiepileptic drugs (AEDs) (P = 0.03) and low-grade glioma (P = 0.04) were statistically significant predictors for intraoperative seizures. Mean EOR in awake cases was 92.03% and 90.05% in GA cases (P = 0.23). Postoperative deficits were permanent after 3 months only in 5% of awake patients versus 8.3% of GA group (P = 0.59).

CONCLUSION

Awake craniotomy with intraoperative mapping can be done safely for perirolandic gliomas with lower but statistically nonsignificant incidence of intraoperative seizures and this could be attributed to statistically significant lower stimulation intensities required for mapping. Preoperative multiple AEDs and low-grade glioma are significant predictors for intraoperative seizures.

Updated perspectives on awake neurosurgery with cognitive and emotional assessment for patients with low-grade gliomas

Introduction: Thanks to early extensive surgical resection combined with medical oncological therapies, life expectancy dramatically increased in low-grade glioma (LGG), with an overall survival currently over 15 years. Therefore, patients should be able to maintain valuable family and socio-professional activities.Areas covered: For many decades, cognitive and emotional aspects were neglected by surgical and medical neurooncologists. The goal of surgery was to avoid hemiplegia and/or aphasia, with no considerations regarding behavior. However, because LGG patients live longer, they must be cognitively and affectively able to make long-term projects. Preservation of higher-order functions should be considered systematically in LGG surgery by means of awake cognitive/emotional mapping and monitoring.Expert opinion: The aim is to incorporate recent advances in neurosciences, which proposed revisited models of cerebral processing relying on a meta-network perspective, into the pre-, intra- and postoperative procedure. In this connectomal approach, brain functions result from complex interactions within and between neural networks. This improved understanding of a constant instability of the neural system allows a better cognitive/emotional assessment before and after each treatment over years, in order to preserve personality and adaptive behavior for each LGG patient, based on his/her own definition of quality of life. It is time to create oncological neurosciences.

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.

Predictors of early postoperative epileptic seizures after awake surgery in supratentorial diffuse gliomas

OBJECTIVE

Functional-based resection under awake conditions had been associated with a nonnegligible rate of intraoperative and postoperative epileptic seizures. The authors assessed the incidence of intraoperative and early postoperative epileptic seizures after functional-based resection under awake conditions.

METHODS

The authors prospectively assessed intraoperative and postoperative seizures (within 1 month) together with clinical, imaging, surgical, histopathological, and follow-up data for 202 consecutive diffuse glioma adult patients who underwent a functional-based resection under awake conditions.

RESULTS

Intraoperative seizures occurred in 3.5% of patients during cortical stimulation; all resolved without any procedure being discontinued. No predictor of intraoperative seizures was identified. Early postoperative seizures occurred in 7.9% of patients at a mean of 5.1 ± 2.9 days. They increased the duration of hospital stay (p = 0.018), did not impact the 6-month (median 95 vs 100, p = 0.740) or the 2-year (median 100 vs 100, p = 0.243) postoperative Karnofsky Performance Status score and did not impact the 6-month (100% vs 91.4%, p = 0.252) or the 2-year (91.7 vs 89.4%, p = 0.857) postoperative seizure control. The time to treatment of at least 3 months (adjusted OR [aOR] 4.76 [95% CI 1.38-16.36], p = 0.013), frontal lobe involvement (aOR 4.88 [95% CI 1.25-19.03], p = 0.023), current intensity for intraoperative mapping of at least 3 mA (aOR 4.11 [95% CI 1.17-14.49], p = 0.028), and supratotal resection (aOR 6.24 [95% CI 1.43-27.29], p = 0.015) were independently associated with early postoperative seizures.

CONCLUSIONS

Functional-based resection under awake conditions can be safely performed with a very low rate of intraoperative and early postoperative seizures and good 6-month and 2-year postoperative seizure outcomes. Intraoperatively, the use of the lowest current threshold producing reproducible responses is mandatory to reduce seizure occurrence intraoperatively and in the early postoperative period.

Scale-Free Analysis of Intraoperative ECoG During Awake Craniotomy for Glioma

BACKGROUND

Electrocorticography (ECoG) has been utilized in many epilepsy cases however, the use of this technique for evaluating electrophysiological changes within tumoral zones is spare. Nonetheless, epileptic activities seem to arise from the neocortex surrounding the gliomas suggesting a link between epileptogenesis and glioma cell infiltration in the peritumoral area. The purpose of this study was to implement novel scale-free measures to assess how cortical physiology is altered by the presence of an invasive brain tumor.

METHODS

Twelve patients undergoing an awake craniotomy for resection of a supratentorial glioma were included. ECoG data over the main tumor and the exposed surroundings was acquired intra-operatively just prior to tumor resection. Six of the patients presented with seizures and had data acquired both in the awake and anesthetic state. The corresponding anatomical location of each electrode in relation to the macroscopically-detectable tumor was recorded using the neuronavigation system based on structural anatomical images obtained pre-operatively. The electrodes were classified into tumoral, healthy or peritumoral based on the macroscopically detectable tumoral tissue from the pre-operative structural MRI.

RESULTS

The electrodes overlying the tumoral tissue revealed higher power law exponent (PLE) values across tumoral area compared to the surrounding tissues. The difference between the awake and anesthetic states was significant in the tumoral and healthy tissue (p < 0.05) but not in the peritumoral tissue. The absence of a significant PLE reduction in the peritumoral tissue from the anesthetic to the awake state could be considered as an index of the presence or absence of infiltration of tumor cells into the peritumoral tissue.

CONCLUSIONS

The current study portrays for the first time distinct power law exponent features in the tumoral tissue, which could provide a potential novel electrophysiological marker in the future. The distinct features seen in the peritumoral tissue of gliomas seem to indicate the area where both the onset of epileptiform activity and the tumor infiltration take place.

Use of the train-of-five bipolar technique to provide reliable, spatially accurate motor cortex identification in asleep patients

OBJECTIVE

Intraoperative cortical and subcortical mapping techniques have become integral for achieving a maximal safe resection of tumors that are in or near regions of eloquent brain. The recent literature has demonstrated successful motor/language mapping with lower rates of stimulation-induced seizures when using monopolar high-frequency stimulation compared to traditional low-frequency bipolar stimulation mapping. However, monopolar stimulation carries with it disadvantages that include more radiant spread of electrical stimulation and a theoretically higher potential for tissue damage. The authors report on the successful use of bipolar stimulation with a high-frequency train-of-five (TOF) pulse physiology for motor mapping.

METHODS

Between 2018 and 2019, 13 patients underwent motor mapping with phase-reversal and both low-frequency and high-frequency bipolar stimulation. A retrospective chart review was conducted to determine the success rate of motor mapping and to acquire intraoperative details.

RESULTS

Thirteen patients underwent both high- and low-frequency bipolar motor mapping to aid in tumor resection. Of the lesions treated, 69% were gliomas, and the remainder were metastases. The motor cortex was identified at a significantly greater rate when using high-frequency TOF bipolar stimulation (n = 13) compared to the low-frequency bipolar stimulation (n = 4) (100% vs 31%, respectively; p = 0.0005). Intraoperative seizures and afterdischarges occurred only in the group of patients who underwent low-frequency bipolar stimulation, and none occurred in the TOF group (31% vs 0%, respectively; p = 0.09).

CONCLUSIONS

Using a bipolar wand with high-frequency TOF stimulation, the authors achieved a significantly higher rate of successful motor mapping and a low rate of intraoperative seizure compared to traditional low-frequency bipolar stimulation. This preliminary study suggests that high-frequency TOF stimulation provides a reliable additional tool for motor cortex identification in asleep patients.

Clinical Diagnosis and Perioperative Management of Glioma-Related Epilepsy

Gliomas account for more than half of all adult primary brain tumors. Epilepsy is the most common initial clinical presentation in gliomas. Glioma related epilepsy (GRE) is defined as symptomatic epileptic seizures secondary to gliomas, occurring in nearly 50% in high-grade glioma (HGG) patients and up to 90% in patients with low-grade glioma (LGG). Uncontrolled seizures, which have major impact on patients’ quality of life, are caused by multiple factors. Although the anti-seizure medications (ASMs), chemotherapy and radiation therapy are also beneficial for seizure treatment, the overall seizure control for GRE continue to be unsatisfactory. Due to the close relationship between GRE and glioma, surgical resection is often the treatment of choice not only for the tumor treatment, but also for the seizure control. Despite aggressive surgical treatment, there are about 30% of patients continue to have poor seizure control postoperatively. Furthermore, the diagnostic criteria for GRE is not well established. In this review, we propose an algorithm for the diagnosis and perioperative management for GRE.

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.

Analysis of Intraoperative Seizures During Bipolar Brain Mapping in Eloquent Areas: Intraoperative Seizures in brain mapping

OBJECTIVES

Awake Craniotomy (AC) is a very well described technique that is performed to make an adequate tumor resection preserving the functionality of the patient. Intraoperative Seizures (IS) are reported as a failure of such procedure. We analyze the incidence and risk factor during AC.

METHODS

We made a review of the database of the National Institute of Neurology and Neurosurgery between January 2017 and May 2019 for intrinsic tumors located in eloquent areas of the brain. An analysis of ISconcerning the clinical history, clinical presentation, imaging techniques, histological findings and surgical technique was made. The factors associated with Mapping Failure (MF) were also evaluated.

RESULTS

45 patients were included of whom 7 patients (15.6%) developed IS after cortical-subcortical stimulation, 5 presented partial motor seizures (11.1%) and 2 experimented generalized secondary seizures (4.5%). Of the patients that had a MF, one patient (14%) was due to generalized tonic-clonic seizures which couldn't be managed by cold saline irrigation and administration of anti-seizures drugs and was then converted to a general anesthetic technique. We observed that the patients that had a bigger tumoral volume (112.2 cm3 85.3, P = 0,07) had a bigger positive relation in presenting IS, having a peak sensibility and specificity above 70 cc (ROC).

CONCLUSIONS

In our analysis IS are more common in patients with high presurgical tumor volume. Even though the majority of the patients that presented IS didn't develop MF, it is important to acknowledge that the multidisciplinary group in the operating room must be prepared to detect these complications, treat them promptly and avoid MF.

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.

Awake Craniotomy with Functional Mapping for Glioma Resection in a Limited-Resource-Setting: Preliminary Experience from a Lower-Middle Income Country

BACKGROUND

Awake craniotomy with brain mapping aims to maximize resection of gliomas located within eloquent regions while minimizing the risk of postoperative deficits. This technique is common practice in the developed world but has yet to be implemented in most low- and middle-income countries (LMICs). We assessed the feasibility, safety, and efficiency of functional-based glioma resection using minimal facilities in a limited-resource institution.

METHODS

This is a retrospective review of patients harboring gliomas within eloquent regions who underwent awake craniotomy and tumor resection guided by cortico-subcortical mapping at a tertiary hospital of an LMIC. Patient characteristics, surgical results, and functional outcomes were studied.

RESULTS

Twenty consecutive patients with a mean age of 37 years were enrolled in the study. Seizure, present in 70% of patients, was the major presenting symptom. Eighteen patients had diffuse low-grade gliomas and 2 patients had high-grade gliomas. Intraoperative events were dominated by seizures, occurring in 5 patients (25%). The average extent of tumor removal was 89.5% and the rate of total and subtotal removal was 85%. New postoperative deficits were observed in 5 patients (25%), and permanent deficits were found in 1 patient (5%). The main hurdles encountered were the difficulties in investigating patients and human resource availability.

CONCLUSIONS

Awake craniotomy with brain mapping for functional-based resection of gliomas can be safely achieved in a limited-resource institution with good functional and oncologic results.

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.

Intraoperative Use of Functional MRI for Surgical Decision Making after Limited or Infeasible Electrocortical Stimulation Mapping

BACKGROUND AND PURPOSE

Functional magnetic resonance imaging (fMRI) is becoming widely recognized as a key component of preoperative neurosurgical planning, although intraoperative electrocortical stimulation (ECS) is considered the gold standard surgical brain mapping method. However, acquiring and interpreting ECS results can sometimes be challenging. This retrospective study assesses whether intraoperative availability of fMRI impacted surgical decision-making when ECS was problematic or unobtainable.

METHODS

Records were reviewed for 191 patients who underwent presurgical fMRI with fMRI loaded into the neuronavigation system. Four patients were excluded as a bur-hole biopsy was performed. Imaging was acquired at 3 Tesla and analyzed using the general linear model with significantly activated pixels determined via individually determined thresholds. fMRI maps were displayed intraoperatively via commercial neuronavigation systems.

RESULTS

Seventy-one cases were planned ECS; however, 18 (25.35%) of these procedures were either not attempted or aborted/limited due to: seizure (10), patient difficulty cooperating with the ECS mapping (4), scarring/limited dural opening (3), or dural bleeding (1). In all aborted/limited ECS cases, the surgeon continued surgery using fMRI to guide surgical decision-making. There was no significant difference in the incidence of postoperative deficits between cases with completed ECS and those with limited/aborted ECS.

CONCLUSIONS

Preoperative fMRI allowed for continuation of surgery in over one-fourth of patients in which planned ECS was incomplete or impossible, without a significantly different incidence of postoperative deficits compared to the patients with completed ECS. This demonstrates additional value of fMRI beyond presurgical planning, as fMRI data served as a backup method to ECS.

A probabilistic map of negative motor areas of the upper limb and face: a brain stimulation study

Negative motor responses (NMRs) are defined as movement arrests induced by direct electrical stimulation of the brain. The NMRs manifest themselves after the disruption of a corticosubcortical network involved in motor control, referred to as the 'negative motor network'. At present, the spatial topography of the negative motor areas (NMAs) is poorly known. Hence, the objectives of the present study were to establish the first probabilistic map of the NMAs of the upper limbs and face, identify potential subareas, and investigate the NMAs' relationships with the primary motor cortex. A total of 117 patients with low grade glioma underwent awake surgery with direct electrostimulation. The Montreal Neurological Institute coordinates of sites eliciting NMRs (face and upper limbs) were registered. A probabilistic map was created, and subareas were identified in a cluster analysis. Each cluster was then plotted on the Glasser atlas and the 1200 Subjects Group Average Data from the Human Connectome Project, in order to study connectivity and compare the results with recent parcellation data. We elicited 386 NMRs (mean ± standard deviation current intensity: 2.26 ± 0.5 mA) distributed throughout the precentral gyrus in both hemispheres. In each hemisphere, we found two clusters for facial NMRs. For upper limb NMRs, we found two clusters in the right hemisphere; and three in the left. Each cluster overlapped with parcellations from the Glasser atlas. For the face, the NMAs were associated with areas 55b and 6v. For the upper limbs, the NMAs were linked to areas 6v, 6d, and 55b. Each NMA cluster showed a specific pattern of functionally connected areas, such as the inferior frontal gyrus, supplementary motor area, parietal areas, and posterior superior temporal gyrus. The white matter pathways projecting to these subareas involved the frontal aslant tract and the frontostriatal tract-both of which are well known to be associated with NMRs. This study constitutes the largest series to date of NMRs mapped to the lateral surface of both hemispheres. Rather than being randomly distributed, the NMAs appeared to be well structured and corresponded to parcellations identified by functional neuroimaging. Moreover, the white matter pathways known to drive NMRs are also connected to regions encompassing NMAs. Taken as a whole, our results suggest that NMAs belong to a large-scale modulatory motor network. Our new probabilistic map might constitute a valuable tool for use in further clinical and fundamental studies of motor control.

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.

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.

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.

Clinical practice guidelines for the diagnosis and treatment of adult diffuse glioma-related epilepsy

BACKGROUND

Glioma-related epilepsy (GRE) is defined as symptomatic epileptic seizures secondary to gliomas, it brings both heavy financial and psychosocial burdens to patients with diffuse glioma and significantly decreases their quality of life. To date, there have been no clinical guidelines that provide recommendations for the optimal diagnostic and therapeutic procedures for GRE patients.

METHODS

In March 2017, the Joint Task Force for GRE of China Association Against Epilepsy and Society for Neuro-Oncology of China launched the guideline committee for the diagnosis and treatment of GRE. The guideline committee conducted a comprehensive review of relevant domestic and international literatures that were evaluated and graded based on the Oxford Centre for Evidence-Based Medicine Levels of Evidence, and then held three consensus meetings to discuss relevant recommendations. The recommendations were eventually given according to those relevant literatures, together with the experiences in the diagnosis and treatment of over 3000 GRE cases from 24 tertiary level hospitals that specialize in clinical research of epilepsy, glioma, and GRE in China.

RESULTS

The manuscript presented the current standard recommendations for the diagnostic and therapeutic procedures of GRE.

CONCLUSIONS

The current work will provide a framework and assurance for the diagnosis and treatment strategy of GRE to reduce complications and costs caused by unnecessary treatment. Additionally, it can serve as a reference for all professionals involved in the management of patients with GRE.