Awake craniotomy: indications, benefits, and techniques

Intraoperative mapping and preservation of executive functions in awake craniotomy: a systematic review

Awake craniotomy (AC) allows intraoperative brain mapping (ioBM) for maximum lesion resection while monitoring and preserving neurological function. Conventionally, language, visuospatial assessment, and motor functions are mapped, while the assessment of executive functions (EF) is uncommon. Impaired EF may lead to occupational, personal, and social limitations, thus, a compromised quality of life. A comprehensive literature search was conducted through Scopus, Medline, and Cochrane Library using a pre-defined search strategy. Articles were selected after duplicate removal, initial screening, and full-text assessment. The demographic details, ioBM techniques, intraoperative tasks, and their assessments, the extent of resection (EOR), post-op EF and neurocognitive status, and feasibility and potential adverse effects of the procedure were reviewed. The correlations of tumor locations with intraoperative EF deficits were also assessed. A total of 13 studies with intraoperative EF assessment of 351 patients were reviewed. Awake-asleep-awake protocol was most commonly used. Most studies performed ioBM using bipolar stimulation, with a frequency of 60 Hz, pulse durations ranging 1-2 ms, and intensity ranging 2-6 mA. Cognitive function was monitored with the Stroop task, spatial-2-back test, line-bisection test, trail-making-task, and digit-span tests. All studies reported similar or better EOR in patients with ioBM for EF. When comparing the neuropsychological outcomes of patients with ioBM of EF to those without it, all studies reported significantly better EF preservation in ioBM groups. Most authors reported EF mapping as a feasible tool to obtain satisfactory outcomes. Adverse effects included intraoperative seizures which were easily controlled. AC with ioBM of EF is a safe, effective, and feasible technique that allows satisfactory EOR and improved neurocognitive outcomes with minimal adverse effects.

Cortical and subcortical intraoperative-monitoring of the visual pathway under general anesthesia in epilepsy surgery

OBJECTIVE

The purpose of this study was to evaluate the applicability of visual evoked potentials (VEP) for intraoperative visual pathway monitoring in epilepsy surgery of the posterior hemispheric quadrant (PHQ) and to correlate it with post-operative visual field status.

METHODS

VEP monitoring was performed in 16 patients (12 females, 7 children). Flash-induced VEP were recorded with strip electrodes from the banks of the calcarine cortex. Latency and amplitude of the first component of VEP (V1-lat, V1-amp) were monitored. Evaluation of the visual field was performed pre- and post-operatively in all patients.

RESULTS

All procedures were successfully completed without adverse events. In 10 patients the strip covered both the inferior and superior calcarine banks, while only one bank was sampled in 6 cases (inferior in 4, superior in 2). Considering one of the two calcarine banks, at the end of the resection VEP had disappeared in 4 patients, whereas a decrease >33.3% in 4 and <20% of V1-amp was recorded in 5 and in 4 cases respectively. The percentage of V1-amp reduction was significantly higher for the patients who experienced a post-operative visual field reduction (p < 0.001). Post-operative visual field deficits were found in patients presenting a reduction >33.3% of V1-amp.

CONCLUSIONS

VEP monitoring is possible and safe in epilepsy surgery under general anesthesia.

SIGNIFICANCE

Intraoperative recording of VEP from the banks of the calcarine cortex allows monitoring the integrity of post-geniculate visual pathways during PHQ resections for epilepsy and it is pivotal to prevent disabling visual field defects, including hemianopia and inferior quadrantanopia.

Awake craniotomy in patients with arteriovenous malformation: A systematic review and meta‑analysis

The present systematic review aimed to identify all the available literature on awake craniotomy (AC) in patients with arteriovenous malformation (AVM) in order to evaluate its safety, risks, benefits and effectiveness. All available literature on AC in patients with AVM was collected and evaluated in an aim to provide a better understanding of its safety, associated risks and benefits. A systematic search for studies employing AC in patients with AVM was conducted using the PubMed, Scopus and ScienceDirect databases without restrictions on the year of publication, language, or study design, from inception up to May 30, 2021. A total of 11 studies published between 2004 and 2021 with 106 patients who underwent ACs were considered eligible. The rate of complete resection was 93% [95% confidence interval (CI), 82 to 100%; I2 0%]. The intraoperative complication rate was 21% (95% CI, 1 to 41%; I2 55%) and the post-operative complication rate was 33% (95% CI, 19 to 48%; I2 40%). During follow-up, the complication rate was 6% (95% CI, 1 to 10%; I2 30%). The post-operative complication rate was higher in the Spetzler-Martin grade (SMG) III-V group (31%; 95% CI, 21 to 42%; I2 46%) than in the SMG I-II group (12%; 95% CI, 2 to 22%; I2 0%). Similarly, the follow-up complication rate was higher in the SMG III-V group (9%; 95% CI, 2 to 16%; I2 34%) than in the SMG I-II group (0%; 95% CI, 0 to 4%; I2 0%). On the whole, the present study provides preliminary evidence to indicate that AC is a possible and useful option for the resection of AVM in selected patients. Well-designed future studies with long-term follow-up are required however, to investigate various aspects of safety and provide solid data for AC in patients with AVM.

Anaesthetic considerations and challenges during awake craniotomy

ABSTRACT

This article summarises the key anaesthetic considerations and challenges surrounding the perioperative management of a patient undergoing awake craniotomy. The main goals include patient comfort, facilitation of patient cooperation during the critical awake phase and maintenance of optimal operating conditions. These are achieved through appropriate patient selection and preparation, familiarity with the complexity of each surgical phase and potential complications that may arise, as well as maintenance of close communication among all team members. Challenges such as loss of patient cooperation, loss of airway, intraoperative nausea and vomiting, seizures, cerebral oedema, hypertension, blood loss and use of intraoperative magnetic resonance imaging are discussed. The importance of teamwork, competence, vigilance and clear management strategies for potential complications to maximise patient outcomes is also highlighted.

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.

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.

Technical Aspects of Motor and Language Mapping in Glioma Patients

Gliomas are infiltrative primary brain tumors that often invade functional cortical and subcortical regions, and they mandate individualized brain mapping strategies to avoid postoperative neurological deficits. It is well known that maximal safe resection significantly improves survival, while postoperative deficits minimize the benefits associated with aggressive resections and diminish patients’ quality of life. Although non-invasive imaging tools serve as useful adjuncts, intraoperative stimulation mapping (ISM) is the gold standard for identifying functional cortical and subcortical regions and minimizing morbidity during these challenging resections. Current mapping methods rely on the use of low-frequency and high-frequency stimulation, delivered with monopolar or bipolar probes either directly to the cortical surface or to the subcortical white matter structures. Stimulation effects can be monitored through patient responses during awake mapping procedures and/or with motor-evoked and somatosensory-evoked potentials in patients who are asleep. Depending on the patient’s preoperative status and tumor location and size, neurosurgeons may choose to employ these mapping methods during awake or asleep craniotomies, both of which have their own benefits and challenges. Regardless of which method is used, the goal of intraoperative stimulation is to identify areas of non-functional tissue that can be safely removed to facilitate an approach trajectory to the equator, or center, of the tumor. Recent technological advances have improved ISM’s utility in identifying subcortical structures and minimized the seizure risk associated with cortical stimulation. In this review, we summarize the salient technical aspects of which neurosurgeons should be aware in order to implement intraoperative stimulation mapping effectively and safely during glioma surgery.

Stress, Anxiety, and Depression Associated With Awake Craniotomy: A Systematic Review

BACKGROUND

Awake craniotomy (AC) enables real-time monitoring of cortical and subcortical functions when lesions are in eloquent brain areas. AC patients are exposed to various preoperative, intraoperative, and postoperative stressors, which might affect their mental health.

OBJECTIVE

To conduct a systematic review to better understand stress, anxiety, and depression in AC patients.

METHODS

PubMed, Scopus, and Web of Science databases were searched from January 1, 2000, to April 20, 2022, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline.

RESULTS

Four hundred forty-seven records were identified that fit our inclusion and exclusion criteria for screening. Overall, 24 articles consisting of 1450 patients from 13 countries were included. Sixteen studies (66.7%) were prospective, whereas 8 articles (33.3%) were retrospective. Studies evaluated stress, anxiety, and depression during different phases of AC. Twenty-two studies (91.7%) were conducted on adults, and 2 studies were on pediatrics (8.3 %). Glioma was the most common AC treatment with 615 patients (42.4%). Awake-awake-awake and asleep-awake-asleep were the most common protocols, each used in 4 studies, respectively (16.7%). Anxiety was the most common psychological outcome evaluated in 19 studies (79.2%). The visual analog scale and self-developed questionnaire by the authors (each n = 5, 20.8%) were the most frequently tools used. Twenty-three studies (95.8%) concluded that AC does not increase stress, anxiety, and/or depression in AC patients. One study (4.2%) identified younger age associated with panic attack.

CONCLUSION

In experienced hands, AC does not cause an increase in stress, anxiety, and depression; however, the psychiatric impact of AC should not be underestimated.

Wide Dissection Trans-Sulcal Approach for Resection of Deep Intra-Axial Lesions in Eloquent Brain Areas

Introduction: Resection of intra-axial tumors (IaT) in eloquent brain regions risks major postoperative neurological deficits. Awake craniotomy is often used to navigate these areas; however, some patients are ineligible for awake procedures. The trans-sulcal approach (TScal) was introduced to reduce parenchymal trauma during tumor resection. We report our experiences utilizing TScal for resection of deep IaT located in eloquent areas. Materials and Methods: This is a single-center retrospective analysis of patients who underwent IaT resection in eloquent areas via TScal from January 2013 to April 2021. Seventeen cases were reviewed, and relevant data was collected. Fluorescence-guided surgery with 5-aminolevulinic acid (ALA) and intraoperative ultrasound was performed in some cases. Results: Seventeen patients (10 males, 7 females) averaging 61.2 years-old (range, 21-76) were included in this study. Average length of stay was 4.8 days, and only 2 patients (11.8%) required hospital readmission within 30 days. Gross total resection (GTR) was achieved in 15 patients (88.2%), while subtotal resection occurred in 2 patients (11.8%). Eleven patients (64.7%) reported full resolution of symptoms, 4 patients (23.5%) reported deficit improvement, and 2 patients (11.8%) experienced no change from their preoperative deficits. No patient developed new permanent deficits postoperatively. Discussion: GTR, preoperative deficit reduction, and complications were comparable to awake craniotomy and other TScal studies. Ancillary intraoperative techniques, such as brain mapping, 5-ALA and intraoperative ultrasound, are afforded by TScal to improve resection rates and overall outcomes. Conclusions: TScal can be an option for patients with deep lesions in eloquent areas who are not candidates for awake surgeries.

Role of Asleep Surgery for Supplementary Motor Area Tumors

Background The supplementary motor area (SMA) is involved in planning of voluntary motor activities. Tumors in SMA usually present with seizures and, rarely, motor deficits. Postoperatively, these patients may develop SMA syndrome. Patients with SMA tumors usually undergo awake craniotomy along with neuromonitoring for maximal safe resection, and some of these patients tend to have residual tumor.

Objective To completely excise the SMA region tumors under general anesthesia without causing any permanent neurological deficits.

Methods We operated upon four patients with SMA region tumor under general anesthesia (GA) with direct electrocortical stimulation (DES). Motor-evoked potential was used to monitor corticospinal tracts through corkscrew or strip electrodes. Intraoperative MRI was done to assess the tumor excision.

Results All four patients had complete resection of tumor and, postoperatively, all four developed SMA syndrome. All of them recovered completely over a period of time.

Conclusion SMA tumors can be excised completely under GA with DES, thereby increasing progression-free survival.

Neuro-Oncology Patients as Human Research Subjects: Ethical Considerations for Cognitive and Behavioral Testing for Research Purposes

Simple Summary

Previous publications have elaborated on the exposure of ethical issues surrounding the enrollment and neurological testing of brain cancer patients into clinical studies. Existing literature has been tailored to provide insight on how to overcome ethical challenges for clinical team members but not for the research component that runs in parallel. The aim of this paper is to highlight the obstacles that researchers encounter when obtaining informed consent and administering language, cognitive or behavioral tasks for the sole purpose of research. Researchers should be encouraged to practice their best judgment and effectively communicate the purpose of the study while emphasizing the voluntary participation of neurologically impaired cancer patients. The solutions proposed in this paper can serve as future reference and a guide on maintaining a transparent balance between research and clinical testing for both researchers and clinical team members in the neuro-oncology field.

Abstract

Language, cognition, and behavioral testing have become a fundamental component of standard clinical care for brain cancer patients. Many existing publications have identified and addressed potential ethical issues that are present in the biomedical setting mostly centering around the enrollment of vulnerable populations for therapeutic clinical trials. Well-established guides and publications have served as useful tools for clinicians; however, little has been published for researchers who share the same stage but administer tests and collect valuable data solely for non-therapeutic investigational purposes derived from voluntary patient participation. Obtaining informed consent and administering language, cognition, and behavioral tasks for the sole purpose of research involving cancer patients that exhibit motor speech difficulties and cognitive impairments has its own hardships. Researchers may encounter patients who experience emotional responses during tasks that challenge their existing impairments. Patients may have difficulty differentiating between clinical testing and research testing due to similarity of task design and their physician’s dual role as a principal investigator in the study. It is important for researchers to practice the proposed methods emphasized in this article to maintain the overall well-being of patients while simultaneously fulfilling the purpose of the study in a research setting.

One day at a time

In this issue of Biomedical Journal we get to know measures to prevent a nosocomial COVID-19 outbreak, a compound that is able to stall SARS-CoV-2 replication, and the connection between air pollution and COVID-19 cases. Another article allows an insight into the potential of treating HIV combining a conventional drug and low level laser therapy. Furthermore, the advantages of awake craniotomy are presented, the efficacy of IRES is examined, and plant extracts are on the one hand explored as a nociceptive agent and on the other hand as therapeutic approach against breast cancer. We learn about drug resistance in liver cancer, a mutation involved in a rare inflammatory disorder, and lung surgery related unilateral vocal fold paralysis. Finally, the success of emergency endotracheal intubations across different hospital units is compared, the importance of monitoring cerebral blood flow in asphyxiated neonates is elucidated, and resistance variants in hepatitis C virus are examined. A study about the necessity to perform quantitative cardiac MRI in Asian population is presented, and an approach is shown on how to augment the effect of platelet-rich plasma injections in chronic knee osteoarthritis.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

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.

Anesthetic Management of Asleep and Awake Craniotomy for Supratentorial Tumor Resection

Understanding how anesthetics impact cerebral physiology, cerebral blood flow, brain metabolism, brain relaxation, and neurologic recovery is crucial for optimizing anesthesia during supratentorial craniotomies. Intraoperative goals for supratentorial tumor resection include maintaining cerebral perfusion pressure and cerebral autoregulation, optimizing surgical access and neuromonitoring, and facilitating rapid, cooperative emergence. Evidence-based studies increasingly expand the impact of anesthetic care beyond immediate perioperative care into both preoperative optimization and minimizing postoperative consequences. New evidence is needed for neuroanesthesia's role in neurooncology, in preventing conversion from acute to chronic pain, and in decreasing risk of intraoperative ischemia and postoperative delirium.

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.

Subjective experience, cognitive functioning and trauma level of patients undergoing awake craniotomy due to brain tumor - Preliminary study

BACKUP AND OBJECTIVE

Awake craniotomy (AC) for brain tumors, when the patient is conscious during the operation, allows to reduce the risk of motor disability and aphasia, however, it may be a source of extreme stress. The aim of our study was to examine the patients' subjective experience of the surgery including the level of psychological trauma and cognitive functioning.

METHOD

Eighteen patients operated due to brain tumor were enrolled in this study. The Essener Trauma-Inventory Questionnaire and the Addenbrooke's Cognitive Examination (ACE III) were administrated. The patients' experience with awake craniotomy was evaluated with a qualitative descriptive survey.

RESULTS

All patients remembered the intraoperative neuropsychological examination and several sensations like: drilling, cold, head clamp fixation or having eyes covered. In most of the patients the postoperative psychological trauma experience did not reach the clinical level. The ACE III postoperative scores revealed partial cognitive deficits with the lowest scores in memory and word fluency domains. Slight amnestic aphasia was observed postoperatively only in two patients.

CONCLUSIONS

Awake craniotomy for resection of brain tumors is well-tolerated by patients and does not cause significant psychological trauma. Nonetheless, anxiety about the procedure warrants further study and individualized neuropsychological care is needed for the emotional preparation of the patient.