Feasibility of awake craniotomy in the pediatric population

Awake craniotomy in pediatric low-grade glioma: barriers and future directions

INTRODUCTION

The goal of surgical management in pediatric low-grade gliomas (pLGGs) is gross total resection (GTR), as it is considered curative with favorable long-term outcomes. Achieving GTR can be challenging in the setting of eloquent-region gliomas, in which resection may increase risk of neurological deficits. Awake craniotomy (AC) with intraoperative neurofunctional mapping (IONM) offers a promising approach to achieve maximal resection while preserving neurological function. However, its adoption in pediatric cases has been hindered, and barriers to its adoption have not previously been elucidated.

FINDINGS

This review includes two complementary investigations. First, a survey study was conducted querying pediatric neurosurgeons on their perceived barriers to the procedure in children with pLGG. Next, these critical barriers were analyzed in the context of existing literature. These barriers included the lack of standardized IONM techniques for children, inadequate surgical and anesthesia experience, concerns regarding increased complication risks, doubts about children's ability to tolerate the procedure, and perceived non-indications due to alternative monitoring tools.

CONCLUSION

Efforts to overcome these barriers include standardizing IONM protocols, refining anesthesia management, enhancing patient preparation strategies, and challenging entrenched beliefs about pediatric AC. Collaborative interdisciplinary efforts and further studies are needed to establish safety guidelines and broaden the application of AC, ultimately improving outcomes for children with pLGG.

The Use of Remimazolam During Awake Craniotomy for Seizure Foci Resection in Adolescents: A Case Series

Remimazolam is a novel benzodiazepine with sedative, anxiolytic, and amnestic properties similar to midazolam. Metabolism by tissue esterases results in a short clinical half-life of 5 - 10 min and a limited context sensitive half-life. We present initial retrospective clinical experience with the use of remimazolam as an intraoperative adjunct to sedation during awake craniotomy in a cohort of three adolescent patients. A remimazolam infusion was added to a combination of dexmedetomidine and remifentanil to deepen the level of sedation during surgical incision, craniotomy, duraplasty, and surgical dissection for exposure of the seizure foci. The remimazolam infusion was discontinued 30 min prior to the planned awake assessments and electrophysiology testing. The patients emerged calmly and were able to follow commands for intraoperative testing. Our anecdotal experience supports the efficacy of remimazolam for awake craniotomy and tumor resection using a standard asleep-awake-asleep technique. We noted adequate sedation, maintenance of spontaneous respiration, rapid awakening, and no limitations to intraoperative neuromonitoring or awake assessment in our three patients.

How often do awake craniotomies in children and adolescents lead to panic and worry?

PURPOSE

Awake craniotomy (AC) is the treatment of choice for the resection of brain tumors within eloquent brain regions for adults, but not much is known about its psychological impact on children and adolescents. Patient immaturity and difficulty in cooperating during surgery could result in psychological sequelae postoperatively, such as anxiety, panic, and worry.

METHODS

In this review, we examined eight studies assessing AC performed on patients under 18 years of age (N = 85), noting exclusion criteria, interventions used, and psychological assessments implemented.

RESULTS

Initial assessments of cognitive functioning and maturity were conducted primarily to determine patient eligibility for AC instead of an age restriction. No standardized interventions were used to minimize anxiety associated with AC. Interventions ranged from almost nothing specified to exposure to videos of the operating room, hypnosis, repeated meetings with psychologists and speech therapists, extensive meetings with the surgery team, and thorough exposure to the operating room theater. With a few exceptions, there were no standardized pre- and post-AC assessments of psychological sequelae. Qualitative evaluations indicated that most children and adolescents tolerated AC well, but one study indicated detrimental effects on school attendance postoperatively.

CONCLUSION

Given that most AC teams have a psychologist, it seems desirable to have pre- and post-AC psychological assessments using standardized measures of anxiety, trauma, and worry, as well as measures tailored to AC, such as time to return to school, worry about MRIs following surgery, and self-assessment of post-surgery functioning. In short, comprehensive psychological assessment of AC patients is clearly needed.

Awake Craniotomy in Pediatric Patients: A Meta-analysis of Operative Outcomes

BACKGROUND

Awake craniotomy allows neurosurgeons to make critical decisions when operating in eloquent regions of the brain. The phenomenon of "waking up" during surgery is underexplored in pediatric patients, and the operative outcomes following awake craniotomy are not well understood. Correspondingly, the aim of this study was to quantitatively aggregate the contemporary metadata regarding the operative outcomes of awake craniotomy when used in the pediatric setting.

METHODS

Multiple electronic databases from inception to June 2023 were searched following PRISMA guidelines. Respective cohort-level outcomes were then abstracted and pooled by means of meta-analysis utilizing random-effects modeling, and trends evaluated by meta-regression analysis.

RESULTS

There were 4 observational studies that satisfied all selection criteria, describing a total cohort of 57 pediatric patients undergoing awake craniotomy. There were 34 (60%) male patients with a median age of 14 years old, with lesions on the left side in 80% of cases when reported. Meta-analysis demonstrated pooled incidences of intraoperative complication to be 17% (95% CI 4%-37%), the need to convert cases to general anesthesia to be 2% (95% CI 0%-9%), immediate postoperative complication to be 18% (95% CI 6%-33%), and long-term complications to be 6% (95% CI 0%-15%). The most common intraoperative complication reported was seizure. Certainty of these estimates were very low due to limited metadata. Meta-regression did not indicate any trend bias due to study and cohort parameters.

CONCLUSIONS

Multiple studies have demonstrated the feasibility of the awake craniotomy approach in pediatric patients. The risks for intraoperative and postoperative complications are non-zero, with their incidences trending towards incidences seen in the adult demographic. It is likely formal neuropsychologic preparation and follow-up will increase the candidacy and success of this approach in the future.

Structural networking of the developing brain: from maturation to neurosurgical implications

Modern neuroscience agrees that neurological processing emerges from the multimodal interaction among multiple cortical and subcortical neuronal hubs, connected at short and long distance by white matter, to form a largely integrated and dynamic network, called the brain "connectome." The final architecture of these circuits results from a complex, continuous, and highly protracted development process of several axonal pathways that constitute the anatomical substrate of neuronal interactions. Awareness of the network organization of the central nervous system is crucial not only to understand the basis of children's neurological development, but also it may be of special interest to improve the quality of neurosurgical treatments of many pediatric diseases. Although there are a flourishing number of neuroimaging studies of the connectome, a comprehensive vision linking this research to neurosurgical practice is still lacking in the current pediatric literature. The goal of this review is to contribute to bridging this gap. In the first part, we summarize the main current knowledge concerning brain network maturation and its involvement in different aspects of normal neurocognitive development as well as in the pathophysiology of specific diseases. The final section is devoted to identifying possible implications of this knowledge in the neurosurgical field, especially in epilepsy and tumor surgery, and to discuss promising perspectives for future investigations.

Awake Craniotomy Surgery in Pediatrics: A Systematic Review

BACKGROUND

Awake craniotomy is a unique method to prevent motor deficits during the resection of lesions located in or close to functional areas. We sought to study the outcomes of pediatric craniotomy on published studies.

METHODS

The search for articles was performed through multiple search engines: PubMed, Google Scholar, Web of Science, and Wiley. The following search terms were used for screening the titles and abstracts: "awake brain surgery" and "children" or "pediatrics," "awake craniotomy," and "children" or "pediatrics," "pediatrics awake craniotomy," "awake brain surgery pediatrics," and "tumors." On initial screening of the titles and abstracts, 54 articles were found. After a thorough review of the full texts of obtained articles and removing duplicates, 16 articles remained.

RESULTS

The mean age group was 12.23 years. There was a slight difference between genders who underwent awake craniotomy in the pediatric age group, 52.7% male and 47.3% for female. Tumor resection was the most common indication of the surgery. Almost half (47.9%) experienced complete recovery following the surgery. However, of those who had complicated recovery, 7.5% experienced a speech deficit.

CONCLUSIONS

This systematic review summarized that awake brain surgery can prevent significant motor and language deficits postoperatively in children after tumor resection as it is considered a feasible and safe procedure.

Intraoperative neurophysiology in pediatric neurosurgery: a historical perspective

INTRODUCTION

Intraoperative neurophysiology (ION) has been established over the past three decades as a valuable discipline to improve the safety of neurosurgical procedures with the main goal of reducing neurological morbidity. Neurosurgeons have substantially contributed to the development of this field not only by implementing the use and refinement of ION in the operating room but also by introducing novel techniques for both mapping and monitoring of neural pathways.

METHODS

This review provides a personal perspective on the evolution of ION in a variety of pediatric neurosurgical procedures: from brain tumor to brainstem surgery, from spinal cord tumor to tethered cord surgery.

RESULTS AND DISCUSSION

The contribution of pediatric neurosurgeons is highlighted showing how our discipline has played a crucial role in promoting ION at the turn of the century. Finally, a view on novel ION techniques and their potential implications for pediatric neurosurgery will provide insights into the future of ION, further supporting the view of a functional, rather than merely anatomical, approach to pediatric neurosurgery.

Surgical Outcomes of Awake Craniotomy for Treatment of Arteriovenous Malformations in Eloquent Cortex: A Systematic Review

OBJECTIVE

Arteriovenous malformations (AVMs) located in eloquent brain regions are historically associated with a poor prognosis. Awake craniotomy (AC) with the adjunct of brain mapping has the potential of identifying non-eloquent gyri to maximize resection, thereby theoretically decreasing the risk of neurologic deficits. With limited evidence regarding the efficacy of AC in treatment of eloquent AVMs, this review aims to investigate its surgical outcomes.

METHODS

A systematic search in the PubMed database was performed to identify all relevant studies up to February 2022.

RESULTS

A total of 13 studies were extracted for quantitative analysis, yielding a total of 46 patients. The mean age was 34.1 years, and most patients were female (54.8%). Seizures were the most frequently reported presenting symptom (41%, 19 of 46 cases). Spetzler-Martin Grade III was the most prevalent (45.9%, 17 cases) with a mean nidus size of 32.6 mm. Seventy-four percent of AVMs were located on the left side, with the frontal lobe being the most common location (30%, 14 of 46 cases). The most common eloquent regions were language (47.8%, 22 of 46 cases), motor (17.4%, 8 of 46 cases), and language + motor cortices (13.1%, 6 of 46 cases). Complete resection of AVM was achieved in 41 patients (89%). Intraoperative complications occurred in 14 of 46 cases (30.4%) with transient postoperative neurologic deficits in 14 patients (30.4%).

CONCLUSIONS

AC may enable precise microsurgical excision of eloquent AVMs with preservation of critical brain functions. Risk factors for poor outcomes include eloquent AVMs located in the language + motor regions and the occurrence of intraoperative complications such as seizures/hemorrhage.

A successful awake pediatric neurosurgery procedure following, 3 months after, a previous failure due to an emergence agitation: a case report

Awake neurosurgery in children may sometimes require conversion to general anesthesia. We present here the case of a first failed awake procedure for epilepsy surgery. After adapting the anesthesia protocol (sedation + hypnosis) and acceptance by the patient, the surgeons operated the child in good conditions a few months later. We believe that it is possible to retry awake neurosurgery after a first failure if its analysis showed modifiable causes.

Impact of intraoperative direct cortical stimulation dynamics on perioperative seizures and afterdischarge frequency in patients undergoing awake craniotomy

OBJECTIVE

Intraoperative stimulation is used as a crucial adjunct in neurosurgical oncology, allowing for greater extent of resection while minimizing morbidity. However, limited data exist regarding the impact of cortical stimulation on the frequency of perioperative seizures in these patients.

METHODS

A retrospective chart review of patients undergoing awake craniotomy with electrocorticography data by a single surgeon at the authors' institution between 2013 and 2020 was conducted. Eighty-three patients were identified, and electrocorticography, stimulation, and afterdischarge (AD)/seizure data were collected and analyzed. Stimulation characteristics (number, amplitude, density [stimulations per minute], composite score [amplitude × density], total and average stimulation duration, and number of positive stimulation sites) were analyzed for association with intraoperative seizures (ISs), ADs, and postoperative clinical seizures.

RESULTS

Total stimulation duration (p = 0.005), average stimulation duration (p = 0.010), and number of stimulations (p = 0.020) were found to significantly impact AD incidence. A total stimulation duration of more than 145 seconds (p = 0.04) and more than 60 total stimulations (p = 0.03) resulted in significantly higher rates of ADs. The total number of positive stimulation sites was associated with increased IS (p = 0.048). Lesions located within the insula (p = 0.027) were associated with increased incidence of ADs. Patients undergoing repeat awake craniotomy were more likely to experience IS (p = 0.013). Preoperative antiepileptic drug use, seizure history, and number of prior resections of any type showed no impact on the outcomes considered. The charge transferred to the cortex per second during mapping was significantly higher in the 10 seconds leading to AD than at any other time point examined in patients experiencing ADs, and was significantly higher than any time point in patients not experiencing ADs or ISs. Although the rate of transfer for patients experiencing ISs was highest in the 10 seconds prior to the seizure, it was not significantly different from those who did not experience an AD or IS.

CONCLUSIONS

The data suggest that intraoperative cortical stimulation is a safe and effective technique in maximizing extent of resection while minimizing neurological morbidity in patients undergoing awake craniotomies, and that surgeons may avoid ADs and ISs by minimizing duration and total number of stimulations and by decreasing the overall charge transferred to the cortex during mapping procedures.

Pediatric Neuroanesthesia — a Review of the Recent Literature

Purpose of Review

Pediatric neuroanesthesia is a growing and still challenging subspecialty. The purpose of this review is to summarize the available knowledge and highlight the most recent findings of the literature on non-traumatic pediatric neuroanesthesia care.

Recent Findings

Several human studies have confirmed the negative effects of early life anesthetic exposure. According to non-human studies, volatile anesthetics and opioids contribute to tumor progression. Tranexamic acid effectively reduces perioperative blood loss; it is used in several different doses without standard guidelines on optimal dosing. The widespread use of neuromonitoring has necessitated the development of anesthetic methods that do not affect neuromuscular transmission.

Summary

Pediatric anesthetic neurotoxicity, management of intraoperative bleeding, and the effect of anesthesia on tumor growth are among the most debated and researched topics in pediatric neuroanesthesia. The lack of evidence and clinical guidelines underlines the need for further large prospective studies in this subspecialty.

Language improvement after awake craniotomy in a 12-year-old child: illustrative case

BACKGROUND

Although the standard procedure to treat adult patients with lesions in eloquent brain areas is awake craniotomy with direct electrical stimulation, this procedure is not often used in children because of feasibility concerns. Some studies have shown that the procedure is feasible in children. They reported the postoperative language ability, which was not based on standardized language tests for children. To give an objective overview of preoperative assessment of the language ability of a child before and after this procedure, the authors described the perioperative course, including standardized language tests for children and the awake surgery setting, of a 12-year-old child undergoing awake craniotomy with brain mapping for the indication of cavernoma in the left somatosensory cortex close to the motor cortex.

OBSERVATIONS

The patient performed better on language tests after surgery, showing that his language ability improved. He also cooperated well during the entire perioperative period. His mother was present during the awake surgery, and the patient tolerated the surgery well.

LESSONS

The authors conclude that awake craniotomy is indeed feasible in a child and that it can even result in an improved postoperative language outcome. It is, however, crucial to carefully assess, inform, and monitor the child and their proxies.

Sevoflurane-based enhancement of phase-amplitude coupling and localization of the epileptogenic zone

OBJECTIVE

Phase-amplitude coupling between high-frequency (≥150 Hz) and delta (3-4 Hz) oscillations - modulation index (MI) - is a promising, objective biomarker of epileptogenicity. We determined whether sevoflurane anesthesia preferentially enhances this metric within the epileptogenic zone.

METHODS

This is an observational study of intraoperative electrocorticography data from 621 electrodes chronically implanted into eight patients with drug-resistant, focal epilepsy. All patients were anesthetized with sevoflurane during resective surgery, which subsequently resulted in seizure control. We classified 'removed' and 'retained' brain sites as epileptogenic and non-epileptogenic, respectively. Mixed model analysis determined which anesthetic stage optimized MI-based classification of epileptogenic sites.

RESULTS

MI increased as a function of anesthetic stage, ranging from baseline (i.e., oxygen alone) to 2.0 minimum alveolar concentration (MAC) of sevoflurane, preferentially at sites showing higher initial MI values. This phenomenon was accentuated just prior to sevoflurane reaching 2.0 MAC, at which time, the odds of a site being classified as epileptogenic were enhanced by 86.6 times for every increase of 1.0 MI.

CONCLUSIONS

Intraoperative MI best localized the epileptogenic zone immediately before sevoflurane reaching 2.0 MAC in this small cohort of patients.

SIGNIFICANCE

Prospective, large cohort studies are warranted to determine whether sevoflurane anesthesia can reduce the need for extraoperative, invasive evaluation.

Pediatric awake epilepsy surgery: Intraoperative language mapping utilizing digital video gaming and electrocorticography

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Awake craniotomy for language mapping in children requires a specific perioperative strategy.

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Extraoperative language cortical mapping using a grid electrode provides more optimal setting that reduces anxiety and improves compliance.

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The utilization of video game familiar to the pediatric patient reduce anxiety and enhance cooperation during awake language cortical mapping.

Intraoperative functional language mapping is vital to minimize the risks associated with surgical removal of the seizure onset zone in selected patients with epilepsy. In children, this method has been reported extraoperatively by the placement of invasive electrodes to map the language area and monitor epileptic activity. It is difficult from a technical standpoint to perform an awake craniotomy and language mapping in young children under 10 years of age. Here we report a 9-year-old boy suffering from drug-resistant non-lesional epilepsy who underwent extraoperative and intraoperative electrical stimulation with successful identification of Broca’s language area. Electrocorticography (ECOG) was applied intraoperatively in a continuous manner utilizing grid electrodes before the skin opening. We found that the use of visual digital video games facilitated extraoperative and intraoperative cortical mapping. Cortical language inhibition by electrical stimulation was elicited at an amplitude of 7 mA (100 μs single-phase duration and 50 Hz pulse width). Resection of the seizure onset zone was completed safely. The post-resection ECOG revealed the disappearance of epileptogenic electrographic discharges at the seizure onset contacts and at other involved contacts in the epileptogenic zone. After surgery, the child recovered well with no language deficits and remained seizure-free. The child remembered only the video game test that was performed intraoperatively. This report highlights safety strategies for awake language mapping in pediatrics and the importance of the perioperative use of a visual digital video game and continuous ECOG, in addition to the use of targeted language cortex stimulation to facilitate faster and safer intraoperative language mapping under awake conditions in this age group.