Awake surgery for hemispheric low-grade gliomas: oncological, functional and methodological differences between pediatric and adult populations

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.

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

BACKGROUND

Language mapping during awake craniotomy can allow for precise resection of epileptogenic lesions, while reducing the risk of damage to eloquent cortex. There are few reports in the literature of language mapping during awake craniotomy in children with epilepsy. Some centers may avoid awake craniotomy in the pediatric age group due to concerns that children are unable to cooperate with such procedures.

METHODS

We reviewed pediatric patients from our center with drug-resistant focal epilepsy who underwent language mapping during awake craniotomy and subsequent resection of the epileptogenic lesion.

RESULTS

Two patients were identified, both female, aged 17 years and 11 years at the time of surgery. Both patients had frequent and disabling focal seizures despite trials of multiple antiseizure medications. Both patients had resection of their epileptogenic lesions with the aid of intraoperative language mapping; in both cases pathology was consistent with focal cortical dysplasia. Both patients had transient language difficulties in the immediate postoperative period but no deficits at six-month follow-up. Both patients are now seizure-free.

CONCLUSIONS

Awake craniotomy should be considered in pediatric patients with drug-resistant epilepsy in whom the suspected epileptogenic lesion is in close proximity to cortical language areas.

Passive functional mapping of receptive language cortex during general anesthesia using electrocorticography

OBJECTIVE

To investigate the feasibility of passive functional mapping in the receptive language cortex during general anesthesia using electrocorticographic (ECoG) signals.

METHODS

We used subdurally placed ECoG grids to record cortical responses to speech stimuli during awake and anesthesia conditions. We identified the cortical areas with significant responses to the stimuli using the spectro-temporal consistency of the brain signal in the broadband gamma (BBG) frequency band (70-170 Hz).

RESULTS

We found that ECoG BBG responses during general anesthesia effectively identify cortical regions associated with receptive language function. Our analyses demonstrated that the ability to identify receptive language cortex varies across different states and depths of anesthesia. We confirmed these results by comparing them to receptive language areas identified during the awake condition. Quantification of these results demonstrated an average sensitivity and specificity of passive language mapping during general anesthesia to be 49±7.7% and 100%, respectively.

CONCLUSION

Our results demonstrate that mapping receptive language cortex in patients during general anesthesia is feasible.

SIGNIFICANCE

Our proposed protocol could greatly expand the population of patients that can benefit from passive language mapping techniques, and could eliminate the risks associated with electrocortical stimulation during an awake craniotomy.

Neurosurgery for eloquent lesions in children: state-of-the-art rationale and technical implications of perioperative neurophysiology

OBJECTIVE

In adult patients, an increasing group of neurosurgeons specialize entirely in the treatment of highly eloquent tumors, particularly gliomas. In contrast, extensive perioperative neurophysiological workup for pediatric cases has been limited essentially to epilepsy surgery.

METHODS

The authors discuss radio-oncological and general oncological considerations based on the current literature and their personal experience.

RESULTS

While several functional mapping modalities facilitate preoperative identification of cortically and subcortically located eloquent areas, not all are suited for children. Direct cortical intraoperative stimulation is impractical in many young patients due to the reduced excitability of the immature cortex. Behavioral requirements also limit the utility of functional MRI and magnetoencephalography in children. In contrast, MRI-derived tractography and navigated transcranial magnetic stimulation are available across ages. Herein, the authors review the oncological rationale of function-guided resection in pediatric gliomas including technical implications such as personalized perioperative neurophysiology, surgical strategies, and limitations.

CONCLUSIONS

Taken together, these techniques, despite the limitations of some, facilitate the identification of eloquent areas prior to tumor surgery and radiotherapy as well as during follow-up of residual tumors.

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

OBJECTIVE

The goal of this study was to evaluate the feasibility, benefit, and safety of awake brain surgery (ABS) and intraoperative language mapping in children and adolescents with structural epilepsies. Whereas ABS is an established method to monitor language function in adults intraoperatively, reports of ABS in children are scarce.

METHODS

A retrospective chart review of pediatric patients ≤ 18 years of age who underwent ABS and cortical language mapping for supratentorial tumors and nontumoral epileptogenic lesions between 2008 and 2019 was conducted. The authors evaluated the global intellectual and specific language performance by using detailed neuropsychological testing, the patient's intraoperative compliance, results of intraoperative language mapping assisted by electrocorticography (ECoG), and postsurgical language development and seizure outcomes. Descriptive statistics were used for this study, with a statistical significance of p < 0.05.

RESULTS

Eleven children (7 boys) with a median age of 13 years (range 10-18 years) underwent ABS for a lesion in close vicinity to cortical language areas as defined by structural and functional MRI (left hemisphere in 9 children, right hemisphere in 2). Patients were neurologically intact but experiencing seizures; these were refractory to therapy in 9 patients. Compliance during the awake phase was high in 10 patients and low in 1 patient. Cortical mapping identified eloquent language areas in 6/10 (60%) patients and was concordant in 3/8 (37.5%), discordant in 3/8 (37.5%), and unclear in 2/8 (25%) patients compared to preoperative functional MRI. Stimulation-induced seizures occurred in 2 patients and could be interrupted easily. ECoG revealed that afterdischarge potentials (ADP) were involved in 5/9 (56%) patients with speech disturbances during stimulation. None of these patients harbored postoperative language dysfunction. Gross-total resection was achieved in 10/11 (91%) patients, and all were seizure free after a median follow-up of 4.3 years. Neuropsychological testing using the Wechsler Intelligence Scale for Children and the verbal learning and memory test showed an overall nonsignificant trend toward an immediate postoperative deterioration followed by an improvement to above preoperative levels after 1 year.

CONCLUSIONS

ABS is a valuable technique in selected pediatric patients with lesions in language areas. An interdisciplinary approach, careful patient selection, extensive preoperative training of patients, and interpretation of intraoperative ADP are pivotal to a successful surgery.

The Exoscope in Neurosurgery: An Overview of the Current Literature of Intraoperative Use in Brain and Spine Surgery

Background: Exoscopes are a safe and effective alternative or adjunct to the existing binocular surgical microscope for brain tumor, skull base surgery, aneurysm clipping and both cervical and lumbar complex spine surgery that probably will open a new era in the field of new tools and techniques in neurosurgery. Methods: A Pubmed and Ovid EMBASE search was performed to identify papers that include surgical experiences with the exoscope in neurosurgery. PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses) were followed. Results: A total of 86 articles and 1711 cases were included and analyzed in this review. Among 86 papers included in this review 74 (86%) were published in the last 5 years. Out of 1711 surgical procedures, 1534 (89.6%) were performed in the operative room, whereas 177 (10.9%) were performed in the laboratory on cadavers. In more detail, 1251 (72.7%) were reported as brain surgeries, whereas 274 (16%) and 9 (0.5%) were reported as spine and peripheral nerve surgeries, respectively. Considering only the clinical series (40 studies and 1328 patients), the overall surgical complication rate was 2.6% during the use of the exoscope. These patients experienced complication profiles similar to those that underwent the same treatments with the OM. The overall switch incidence rate from exoscope to OM during surgery was 5.8%. Conclusions: The exoscope seems to be a safe alternative compared to an operative microscope for the most common brain and spinal procedures, with several advantages that have been reached, such as an easier simplicity of use and a better 3D vision and magnification of the surgical field. Moreover, it offers the opportunity of better interaction with other members of the surgical staff. All these points set the first step for subsequent and short-term changes in the field of neurosurgery and offer new educational possibilities for young neurosurgery and medical students.

Pediatric and Adult Low-Grade Gliomas: Where Do the Differences Lie?

Two thirds of pediatric gliomas are classified as low-grade (LGG), while in adults only around 20% of gliomas are low-grade. However, these tumors do not only differ in their incidence but also in their location, behavior and, subsequently, treatment. Pediatric LGG constitute 65% of pilocytic astrocytomas, while in adults the most commonly found histology is diffuse low-grade glioma (WHO II), which mostly occurs in eloquent regions of the brain, while its pediatric counterpart is frequently found in the infratentorial compartment. The different tumor locations require different skillsets from neurosurgeons. In adult LGG, a common practice is awake surgery, which is rarely performed on children. On the other hand, pediatric neurosurgeons are more commonly confronted with infratentorial tumors causing hydrocephalus, which more often require endoscopic or shunt procedures to restore the cerebrospinal fluid flow. In adult and pediatric LGG surgery, gross total excision is the primary treatment strategy. Only tumor recurrences or progression warrant adjuvant therapy with either chemo- or radiotherapy. In pediatric LGG, MEK inhibitors have shown promising initial results in treating recurrent LGG and several ongoing trials are investigating their role and safety. Moreover, predisposition syndromes, such as neurofibromatosis or tuberous sclerosis complex, can increase the risk of developing LGG in children, while in adults, usually no tumor growth in these syndromes is observed. In this review, we discuss and compare the differences between pediatric and adult LGG, emphasizing that pediatric LGG should not be approached and managed in the same way as adult LCG.

Intraoperative Corticocortical Evoked Potentials for Language Monitoring in Epilepsy Surgery

OBJECTIVE

To evaluate the applicability of corticocortical evoked potentials (CCEP) for intraoperative monitoring of the language network in epilepsy surgery under general anesthesia. To investigate the clinical relevance on language functions of intraoperative changes of CCEP recorded under these conditions.

METHODS

CCEP monitoring was performed in 14 epileptic patients (6 females, 4 children) during resections in the left perisylvian region under general anesthesia. Electrode strips were placed on the anterior language area (AL) and posterior language area (PL), identified by structural and functional magnetic resonance imaging. Single-pulse electric stimulations were delivered to pairs of adjacent contacts in a bipolar fashion. During resection, we monitored the integrity of the dorsal language pathway by stimulating either AL by recording CCEP from PL or vice versa, depending on stability and reproducibility of CCEP. We evaluated the first negative (N1) component of CCEP before, during, and after resection.

RESULTS

All procedures were successfully completed without adverse events. The best response was obtained from AL during stimulation of PL in 8 patients and from PL during stimulation of AL in 6 patients. None of 12 patients with a postresection N1 amplitude decrease of 0%-15% from baseline presented postoperative language impairment. Decreases of 28% and 24%, respectively, of the N1 amplitude were observed in 2 patients who developed transient postoperative speech disturbances.

CONCLUSIONS

The application of CCEP monitoring is possible and safe in epilepsy surgery under general anesthesia. Putative AL and PL can be identified using noninvasive presurgical neuroimaging. Decrease of N1 amplitude >15% from baseline may predict postoperative language deficits.

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

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

Technical Considerations in Awake Craniotomy with Cortical and Subcortical Motor Mapping in Preadolescents: Pushing the Envelope

INTRODUCTION

Unlike adult gliomas, the utility of combined application of awake anesthesia and intraoperative neurophysiological monitoring (IONM) for maximal safe resection in eloquent region gliomas (ERG) has not been established for pediatric population while it remains unexplored in preadolescents (below 11 years old).

CASE PRESENTATION

We report 2 cases of awake craniotomy with IONM in an 8 and 9 year old for safe maximal resection of ERG. In both the cases, repeated preoperative visits of the operating room was performed to familiarize and educate the children about intraoperative communication, comfortable positioning, and neurological assessment. Under conscious sedation protocol, cortical and subcortical mapping, and electrocorticography, gross total resection was achieved. In both the cases, there were no postoperative neurodeficits or perioperative complications.

CONCLUSION

Our 2 cases illustrate the first instance of successful use of awake IONM for maximal safe resection of ERG in preadolescent age-group. We believe, with proper preoperative planning and careful titration of anesthetics, it is safe and feasible. The blanket notion that preadolescent age-group should be excluded from awake mapping needs to be challenged, rather curated on a case basis.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

5-Aminolevulinic Acid-Guided Surgery for Recurrent Supratentorial Pediatric Neoplasms

BACKGROUND

The use of 5-aminolevulinic acid (5-ALA) in pediatric neuro-oncology is considered off-label, and little data are available on its use in tumor recurrence surgery. Here we present our experience with 5-ALA fluorescence-guided surgery for recurrent supratentorial tumors in the pediatric population.

METHODS

Eleven pediatric patients presenting with recurrence of a supratentorial high-grade malignancy (5 glioblastoma [GBM], 6 non-GBM) underwent 5-ALA-assisted surgery. Biopsy specimens were obtained from pathological and normal-appearing areas of the tumor margin.

RESULTS

From the margin of the tumor displaying solid fluorescence, a total of 36 samples were obtained. All of these histological samples were found to harbor tumor cells. From areas of vague enhancement, a total of 49 histological samples were taken, of which 38 samples (77%) harbored tumor cells. There was no significant difference in the percentage of biopsy-positive vague fluorescent areas between the GBM cases (80%) and non-GBM cases (75%). A total of 59 biopsy specimens were taken from the tumor margin that appeared completely negative for fluorescence. On analysis, 24 (40.7%) of these specimens demonstrated tumor cells. There was no significant difference in the number of false-negative biopsies between the GBM group (40%) and the non-GBM group (41%).

CONCLUSIONS

The positive predictive value of solid fluorescence is high in recurrent disease but is substantially lower in areas of vague fluorescence. The rate of false-negative fluorescence is high. 5-ALA should be considered as an adjuvant in revision surgery with the aforementioned caveats in mind.

Awake Craniotomy in a Child: Assessment of Eligibility with a Simulated Theatre Experience

Background

Awake craniotomy is a useful surgical approach to identify and preserve eloquent areas during tumour resection, during surgery for arteriovenous malformation resections and for resective epilepsy surgery. With decreasing age, a child's ability to cooperate and mange an awake craniotomy becomes increasingly relevant. Preoperative screening is essential to identify the child who can undergo the procedure safely. Case Description. A 11-year-old female patient presented with a tumour in her right motor cortex, presumed to be a dysembryoplastic neuroepithelial tumour (DNET). We had concerns regarding the feasibility of performing awake surgery in this patient as psychological testing revealed easy distractibility and an inability to follow commands repetitively. We devised a simulated surgical experience to assess her ability to manage such a procedure. During the simulated theatre experience, attempts were made to replicate the actual theatre experience as closely as possible. The patient was dressed in theatre attire and brought into the theatre on a theatre trolley. She was then transferred onto the theatre bed and positioned in the same manner as she would be for the actual surgery. Her head was placed on a horseshoe headrest, and she was made to lie in a semilateral position, as required for the surgery. A blood pressure cuff, pulse oximeter, nasal cannula with oxygen flow, and calf pumps were applied. She was then draped precisely as she would have been for the procedure. Theatre lighting was set as it would be for the surgical case. The application of the monitoring devices, nasal cannula, and draping was meant not only to prepare her for the procedure but to induce a mild degree of stress such that we could assess the child's coping skills and ability to undergo the procedure. The child performed well throughout the simulated run, and surgery was thus offered. An asleep-awake-asleep technique was planned and employed for surgical removal of the tumour. Cortical and subcortical mapping was used to identify the eloquent tissue. Throughout the procedure, the child was cooperative and anxiety free. Follow-up MRI revealed gross total removal of the lesion.

Conclusion

A simulated theatre experience allowed us to accurately determine that this young patient, despite relative contraindications, was indeed eligible for awake surgery. We will continue to use this technique for all our young patients in assessing their eligibility for these procedures.

Pediatric Glioma Outcomes: Predictors of Early Mortality

OBJECTIVE

To assess the early mortality in pediatric glioma and identify predictors of early mortality, which may provide insight into the therapeutic strategies for children with a high risk of early mortality.

METHODS

We used SEER∗Stat 8.3.5 software to extract data of pediatric glioma from the Surveillance, Epidemiology, and End Results database. Logistical regression to identify the independent factors in predicting early mortality.

RESULTS

A total of 3035 male and 2741 female patients were enrolled in the present study. The death rates within 1 month and 3 months after diagnosis were 1.32% and 2.44%, respectively. Early mortality decreased significantly during the past 40 years. Our results showed that glioblastoma, anaplastic glioma, and oligodendroglioma were risk factors of early mortality for children diagnosed with glioma, whereas advanced age, gross total resection, radiation, and chemotherapy were associated with decreased early mortality.

CONCLUSIONS

We found a decrease in early mortality during the past 40 years. The death rates within 1 month and 3 months after diagnosis were 1.32% and 2.44%, respectively. Age at diagnosis, histologic subtype, the extent of resection, chemotherapy, and radiation were associated with early mortality in pediatric glioma.

Feasibility of awake craniotomy in the pediatric population

BACKGROUND

Awake craniotomy with direct cortical stimulation and mapping is the gold standard for resection of lesions near eloquent brain areas, as it can maximize the extent of resection while minimizing the risk of neurological damage. In contrast to the adult population, only small series of awake craniotomies have been reported in children.

AIMS

The aim of our study is to establish the feasibility of awake craniotomy in the pediatric population.

METHODS

We performed a retrospective observational study of children undergoing a supratentorial awake craniotomy between January 2009 and April 2019 in a pediatric tertiary care center. Our primary outcome was feasibility of awake craniotomy, defined as the ability to complete the procedure without conversion to general anesthesia. Our secondary outcomes were the incidence of serious intraoperative complications and the mapping completion rate.

RESULTS

Thirty procedures were performed in 28 children: 12 females and 16 males. The median age was 14 years (range 7-17). The primary diagnosis was tumor (83.3%), epilepsy (13.3%), and arterio-venous malformation (3.3%). The anesthetic techniques were asleep-awake-asleep (96.7%) and conscious sedation (3.3%), all cases supplemented with scalp block and pin-site infiltration. Awake craniotomy was feasible in 29 cases (96.7%), one patient converted to general anesthesia due to agitation. Serious complications occurred in six patients: agitation (6.7%), seizures (3.3%), increased intracranial pressure (3.3%), respiratory depression (3.3%), and bradycardia (3.3%). All complications were quickly resolved and without major consequences. Cortical mapping was completed in 96.6% cases. New neurological deficits occurred in six patients (20%)-moderate in one case and mild in 5-being all absent at 6 months of follow-up.

CONCLUSION

Awake craniotomy with intraoperative mapping can be successfully performed in children. Adequate patient selection and close cooperation between neurosurgeons, anesthesiologists, neuropsychologists, and neurophysiologists is paramount. Further studies are needed to determine the best anesthetic technique in this population group.

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.

Reliability of intraoperative ultrasound in detecting tumor residual after brain diffuse glioma surgery: a systematic review and meta-analysis

Intraoperative ultrasonography (iUS) is considered an accurate, safe, and cost-effective tool to estimate the extent of resection of both high-grade (HGG) and low-grade (DLGG) diffuse gliomas (DGs). However, it is currently missing an evidence-based assessment of iUS diagnostic accuracy in DGs surgery. The objective of review is to perform a systematic review and meta-analysis of the diagnostic performance of iUS in detecting tumor residue after DGs resection. A comprehensive literature search for studies published through October 2018 was performed according to PRISMA-DTA and STARD 2015 guidelines, using the following algorithm: ("ultrasound" OR "ultrasonography" OR "ultra-so*" OR "echo*" OR "eco*") AND ("brain" OR "nervous") AND ("tumor" OR "tumour" OR "lesion" OR "mass" OR "glio*" OR "GBM") AND ("surgery" OR "surgical" OR "microsurg*" OR "neurosurg*"). Pooled sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR-), and diagnostic odds ratio (DOR) of iUS in DGs were calculated. A subgroup analysis for HGGs and DLGGs was also conducted. Thirteen studies were included in the systematic review (665 DGs). Ten articles (409 DGs) were selected for the meta-analysis with the following results: sensitivity 72.2%, specificity 93.5%, LR- 0.29, LR+ 3, and DOR 9.67. Heterogeneity among studies was non-significant. Subgroup analysis demonstrates a better diagnostic performance of iUS for DLGGs compared with HGGs. iUS is an effective technique in assessing DGs resection. No significant differences are seen regarding iUS modality and transducer characteristics. Its diagnostic performance is higher in DLGGs than HGGs and could be worsened by previous treatments, surgical artifacts, and small tumor residue volumes.