Anaesthesia Management for Awake Craniotomy: Systematic Review and Meta-Analysis

Frailty is Not Associated With Awake Craniotomy Outcome: A Single Institution Experience

BACKGROUND AND OBJECTIVES

Patient frailty has been shown to be a powerful predictor of poor surgical outcome across specialties and may guide patient selection. In awake craniotomy, patient selection is particularly important for completion of intraoperative mapping and to reduce conversion to general anesthesia. We evaluated whether frailty is associated with unsuccessful awake craniotomy or poor outcome.

METHODS

We performed a single-center retrospective study of adult patients with tumor, epilepsy, and vascular pathologies that underwent first-time awake craniotomy between 2018 and 2024. The Modified Frailty Index-11 (mFI-11) was calculated for each patient, and frailty was defined as a mFI-11 ≥2. We evaluated the association of frailty with unsuccessful awake craniotomy and postoperative complications.

RESULTS

In total, 143 patients met inclusion criteria. There were 39 (27%) frail patients (mFI-11 ≥ 2) and 104 (73%) nonfrail patients (mFI-11 <2). Frail patients were significantly older ( P < .001), had a higher American Society of Anesthesia classification ( P = .015), higher rates of obstructive sleep apnea ( P = .001), higher body mass index ( P = .035), and glioblastoma ( P < .001) compared with the nonfrail group. Frail patients had longer length of stay ( P = .008) and had more than 2 times increased odds of discharge to skilled nursing facility or inpatient rehab facility ( P = .01). Frail patients had no significant increased risk of conversion to general anesthesia or incomplete mapping, intraoperative deficit, 24-hour postoperative deficit, 30-day readmission, or residual neurologic deficit at follow-up.

CONCLUSION

In our cohort, frailty was associated with higher anesthetic risk and longer length of stay but was not significantly associated with unsuccessful awake craniotomy, postoperative complications, or neurologic outcome.

Remimazolam in neurosurgery

PURPOSE OF REVIEW

Remimazolam represents a novel intravenous anesthetic agent whose use began in 2020. As a new ultrashort-acting benzodiazepine, it has unique pharmacokinetic properties, such as remifentanil, designed to be active and easily transformed into inactive metabolites by tissue esterases. The purpose is to search the literature and evidences to use this new medication in neurosurgery.

RECENT FINDINGS

Currently, it is allowed for procedural sedation and general anesthesia in a few countries. More advantages of this new drug are predictable onset, short duration, rapid recovery profile, low liability for respiratory depression, cardiovascular depression, lack of injection pain, and known reversible agent, flumazenil. A literature search led to the conclusions that remimazolam may maintain better hemodynamic stability and reduce the episodes of hypotension during coil embolization of cerebral aneurysm and that general anesthesia with remimazolam does not alter cerebral metabolism, cerebral blood flow, and cerebral blood volume. Also, because it facilitates safe and quick arousal, it can be a suitable medication for awake craniotomy.

SUMMARY

With more desirable properties such as reduced risk of prolonged sedation and reliable safety margin, it is expected to increase the safety of sedation and general anesthesia in future.

Anesthetic Management of Awake Craniotomy Versus Traditional Craniotomy at a Single Academic Center: A Retrospective Review

Awake craniotomies (AC) are an increasingly popular surgical technique used in medical institutions worldwide. This rise in adoption is largely due to improved patient outcomes and satisfaction. This procedure allows for real-time monitoring of neurological functions, which helps surgeons preserve critical cognitive, language, and motor abilities. As a result, patients tend to retain neurological functions closer to their baseline levels, highlighting the technique's advantages in modern neurosurgery. Neuromonitoring and brain mapping allow surgeons to perform resections more precisely in delicate anatomical areas. We developed and implemented a protocol for awake craniotomy procedures at the University of Mississippi Medical Center a few years ago. The purpose of this study was to assess and analyze the data between anesthetic management of awake craniotomy and traditional craniotomy (TC). We compared patient characteristics, anesthetic management, surgical duration, complications, opioid requirements, and length of hospital stay (LOS). Our results indicated a statistically significant reduction in the opioid requirement for patients in the awake craniotomy group with no difference in the overall length of stay.

Efficacy and safety of anesthetic agents in awake craniotomy using monitored anesthesia care protocol: a systematic review and meta-analysis

Awake craniotomy (AC) facilitates real-time brain mapping, maximizing tumor resection while preserving critical neurological functions. This study systematically reviews the efficacy of several anesthetic protocols under Monitored Anesthesia Care (MAC) during AC, focusing on clinical outcomes. A systematic review and meta-analysis were conducted using data from observational studies and randomized trials involving AC under MAC. Databases searched included PubMed, Embase, and Web of Science. The analysis employed mixed-effects models to assess both the overall rate of the outcomes and the impact of anesthetic agents on clinical outcomes. The primary outcome was the rate of postoperative neurological deficits. Of 468 studies initially identified, 26 met the inclusion criteria. The overall adverse event rate was 23.7%. The pooled proportion of patients with postoperative neurological deficits and intraoperative seizures was 10.45% and 8.8%, respectively. Remifentanil use was associated with a lower risk of neurological deficits in mixed effects meta-analysis (6.9% vs 16.5%), while intraoperative seizure rate was slightly lower with propofol use (7.1% vs. 11.8%). Midazolam use was also associated with lower agitation (5.5% vs. 10.9%). The rate of secondary adverse outcomes other than hypertension (10.2%) and tense brain (10%) were below 10% and comparable to the previous literature. The findings highlight the variability in anesthetic protocols used in MAC for AC. Despite limited evidence regarding safety concerns and potential confounders, Remifentanil, Propofol, and Midazolam appear to be superior to other agents evaluated in these procedures. However, further research is required to draw definitive conclusions.

Practical guidance for monitored anesthesia care during awake craniotomy

Monitored anesthesia care is a feasible option for anesthetic management during awake craniotomy. Patients selected for surgery are thoroughly evaluated by anesthesiologists, primarily focusing on their risk for airway emergencies, such as respiratory depression and obstruction, throughout the procedure. For patients with relative contraindications, a tailored approach is used to assess their suitability. Neuropsychiatric counseling is also helpful for enhancing the patient's ability to participate in and perform the necessary tasks during brain mapping. Building good rapport with the patient is essential for the success of awake craniotomy, as it helps foster trust and cooperation. Analgesia during awake craniotomy is primarily achieved through scalp nerve blocks or infiltration. Among the six scalp nerve blocks, I have described the zygotemporal nerve block in detail. Proper positioning is crucial for both the surgical approach and the safety and comfort of the patient. Even when local anesthetics are effectively administered, many patients may still experience mild to moderate pain during the procedure. This pain is common and transient, typically occurring around the temporal region. In some cases, sedatives or additional analgesics may be necessary. Serious adverse events can arise, including those that require urgent life-saving interventions or those that interfere with brain mapping and the patient's ability to perform tasks. However, MAC in neurosurgery offers the potential for an improved quality of life for individuals with brain tumors or epileptic seizures, as well as for those with disabilities, such as the deaf or visually impaired, in the future.

Awake Craniotomy in Neurosurgery: A Bibliometric Analysis of the Top 100 Most-Cited Articles and Review of Technological Advancements

Awake craniotomy (AC) is a critical neurosurgical technique for maximizing tumor resection in eloquent brain regions while preserving essential neurological functions like speech and motor control. Despite its widespread adoption, no prior bibliometric analysis has evaluated the most influential research in this field. This study analyzed the top 100 most-cited articles on AC to identify key trends, influential works, and authorship demographics. A systematic search of the Web of Science Core Collection on September 17, 2024, yielded 718 publications, with the top 100 ranked by citation count. Analysis revealed a surge in AC research after 2013, peaking in 2021, with the Journal of Neurosurgery contributing significantly (49 articles; 2,611 citations). Themes included functional mapping, anesthetic techniques, and patient outcomes, with technological advancements such as intraoperative MRI and virtual reality enhancing surgical precision. Authorship analysis highlighted a gender disparity, with male authors occupying 77% of first authorship and 88% of senior roles. These findings underscore AC's evolution, foundational studies, and ongoing advancements while emphasizing the need for greater diversity and inclusion in the field.

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.

Dexmedetomidine for awake craniotomy: Systematic review and meta-analysis

INTRODUCTION

For awake craniotomy, monitored anaesthesia care (MAC) had shown relatively lower failure rates. Nevertheless, the conclusion of the appropriate anaesthetic agents, and complications, has not been proposed. Therefore, the systematic review and meta-analysis was done to compare the clinical profile, surgical outcomes, and anesthesia-related complications between dexmedetomidine-based and non-dexmedetomidine regimens during monitored anesthesia care (MAC) for this procedure.

EVIDENCE ACQUISITION

Published clinical trials described MAC, including the amount of anaesthetic drugs, or the number of patients for awake craniotomy between January 1st, 2009 and March 31st, 2022 were reviewed through PubMed, Scopus, Google Scholar, and grey literature index. The standard methodological procedures were following the PRISMA statement with the PROSPERO registration. Twenty-two articles with 2,137 awake craniotomy patients identified as epilepsy surgery, deep brain stimulation procedure, and intracranial surgery closed to an eloquent area with intraoperative awakening for neuro-evaluation were included. The relative risk (RR) regarding surgical outcomes, and anaesthesia-related complications were compared.

EVIDENCE SYNTHESIS

Dexmedetomidine-based versus non-dexmedetomidine anaesthetic regimen revealed no statistically significant differences in surgical outcomes (RR 1.08, 95 %CI 0.94-1.24), conversion to general anaesthesia (RR 0.45, 95 %CI 0.05-3.83), respiratory complications (RR 0.4, 95 %CI 0.12-1.27), and intraoperative nausea and vomiting (RR 0.30, 95 %CI 0.08-1.14). However, the intraoperative seizure was higher in non-dexmedetomidine group (RR 4.26, 95 %CI 1.49-12.16).

CONCLUSION

MAC for awake craniotomy with dexmedetomidine seems to be effective and safe. Randomized controlled trials with standard protocol in specific group of patients and surgical interventions would further demonstrate a clear benefit of dexmedetomidine in awake craniotomy under MAC.

Compassion, communication, and the perception of control: a mixed methods study to investigate patients' perspectives on clinical practices for alleviating distress and promoting empowerment during awake craniotomies

PURPOSE

To inquire into clinical practices perceived to mitigate patients' intraoperative distress during awake craniotomies.

METHODS

This mixed-methods study involved administration of Amsterdam Preoperative Anxiety and Information Scale and PTSD Checklist prior to the awake craniotomy to evaluate anxiety and information-seeking related to the procedure and symptoms of PTSD. Generalized Anxiety Disorder Scale and Depression Module of the Patient Health Questionnaire were administered before and after the procedure to evaluate generalized anxiety and depression. Patient interviews were conducted 2-weeks postprocedure and included a novel set of patient experience scales to assess patients' recollection of intraoperative pain, overall distress, anxiety, distress due to noise, perception of empowerment, perception of being well-prepared, overall satisfaction with anaesthesia management, and overall satisfaction with the procedure. Qualitative data were analysed using conventional content analysis.

RESULTS

Participants (n = 14) had undergone an awake craniotomy for tissue resection due to primary brain tumours or medically-refractory focal epilepsy. Validated self-report questionnaires demonstrated reduced levels of generalized anxiety (pre mean = 8.66; SD = 6.41; post mean= 4.36; SD = 4.24) following the awake craniotomy. Postprocedure interviews revealed very high satisfaction with the awake craniotomy and anaesthesia management and minimal levels of intraoperative pain, anxiety, and distress. The most stressful aspects of the procedure included global recognition of medical diagnosis, anxiety provoked by unfamiliar sights, sounds, and sensations, a perception of a lack of information or misinformation, and long periods of immobility. Important factors in alleviating intraoperative distress included the medical team's ability to promote patient perceptions of control, establish compassionate relationships, address unfamiliar intraoperative sensations, and deliver effective anaesthesia management.

CONCLUSION

Compassion, communication, and patient perception of control were critical in mitigating intraoperative distress. Clinical practice recommendations with implications for all clinicians involved in patient care during awake craniotomies are provided. Use of these interventions and strategies to reduce distress are important to holistic patient care and patient experiences of care and may improve the likelihood of optimal brain mapping procedures to improve clinical outcomes during awake craniotomies.

Development of extended pharmacokinetic models for propofol based on measured blood and brain concentrations

Propofol's pharmacokinetics have been extensively studied using human blood samples and applied to target-controlled infusion systems; however, information on its concentration in the brain remains scarce. Therefore, this study aimed to simultaneously measure propofol plasma and brain concentrations in patients who underwent awake craniotomy and establish new pharmacokinetic model. Fifty-seven patients with brain tumors or brain lesions who underwent awake craniotomy were sequentially assigned to model-building and validating groups. Plasma and brain (lobectomy or uncapping margins) samples were collected at five time-points. The concentration of propofol was measured using high-performance liquid chromatography. Population pharmacokinetic analysis was conducted through a nonlinear mixed-effects modeling program using a first-order conditional estimation method with interactions. Propofol's brain concentrations were higher than its plasma concentrations. The measured brain concentrations were higher than the effect site concentrations using the previous models. Extended models were constructed based on measured concentrations by incorporating the brain/plasma partition coefficient (Kp value). Extended models showed good predictive accuracy for brain concentrations in the validating group. The Kp value functioned as a factor explaining retention in the brain. Our new pharmacokinetic models and Kp value can predict propofol's brain and plasma concentrations, contributing to safer and more stable anesthesia.

Psychological Characteristics of Patients Undergoing Awake Craniotomy With Dexmedetomidine: A Retrospective Analysis

BACKGROUND AND OBJECTIVES

Only few studies have investigated the psychological profile of patient candidates for awake craniotomy (AC). The aim of this study was to describe the multidisciplinary clinical protocol adopted in our hospital and to retrospectively explore differences in psychological characteristic of 51 patients, analyzing association with the tolerability of the procedure.

METHODS

During the preoperative neuropsychological assessment, the Pain Anxiety Symptoms Scale was administered to assess pain-related anxiety. Clinical characteristics and anesthesiological management were retrospectively recollected. The AC procedure was classified as "optimal" or "suboptimal" based on administration of rescue sedative midazolam doses because of psychomotor agitation or emotional distress in excess with respect to our anesthesiological protocol.

RESULTS

The awake procedure was considered optimal in 33 cases (64.7% of total sample). General anesthesia was never required in our patients. No significant differences between optimal and suboptimal groups were found. No single variable was significant as a predictor of outcome on the univariate analysis, and no multivariate predictive model was possible.

CONCLUSION

Although in our experience the Pain Anxiety Symptoms Scale score was not useful in identifying candidates for AC procedures, our multidisciplinary approach provided good results with respect to the tolerability of AC surgery. However, more studies are required to identify psychological profiles and preoperative possible warning signs to find the best course of surgery for each patient.

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 for high-grade gliomas - a prospective cohort study in a UK tertiary-centre

BACKGROUND

Studies from the UK reporting on awake craniotomy (AC) include a heterogenous group of patients which limit the evaluation of the true impact of AC in high-grade glioma (HGG) patients. This study aims to report solely the experience and outcomes of AC for HGG surgery from our centre.

METHODS

A prospective review of all patients who underwent AC for HGG from 2013 to 2019 were performed. Data on patient characteristics including but not limited to demographics, pre- and post-operative Karnofsky performance status (KPS), tumour location and volume, type of surgery, extent of resection (EOR), tumour histopathology, intra- and post-operative complications, morbidity, mortality, disease recurrence, progression-free survival (PFS) and overall survival (OS) from the time of surgery were collected.

RESULTS

Fifteen patients (6 males; 9 females; 17 surgeries) underwent AC for HGG (median age = 55 years). Two patients underwent repeat surgeries due to disease recurrence. Median pre- and post-operative KPS score was 90 (range:80-100) and 90 (range:60-100), respectively. The EOR ranges from 60 to 100 % with a minimum of 80 % achieved in 81.3 % cases. Post-operative complications include focal seizures (17.6 %), transient aphasia/dysphasia (17.6 %), permanent motor deficit (11.8 %), transient motor deficit (5.9 %) and transient sensory disturbance (5.9 %). There were no surgery-related mortality or post-operative infection. The median PFS and OS were 13 (95%CI 5-78) and 30 (95%CI 21-78) months, respectively.

CONCLUSION

This is the first study in the UK to solely report outcomes of AC for HGG surgery. Our data demonstrates that AC for HGG in eloquent region is safe, feasible and provides comparable outcomes to those reported in the literature.

A Comparison of the Asleep-Awake Technique and Monitored Anesthesia Care During Awake Craniotomy: A 10-Year Analysis

Background Awake intracranial surgery with direct electrical stimulation (DES) is considered the gold standard for the resection of tumors affecting the eloquent areas of the brain. Awake craniotomy is a challenge for the anesthesiologist, as the patient's active cooperation is required throughout the operation. There are two frequent techniques, one is asleep-awake-asleep (AAA), and the other is called monitored anesthesia care (MAC). The AAA technique is the longer standing of the two and comprises general anesthesia followed by intraoperative awakening, which is necessary for neurological monitoring. In the present study, a comparison was made between the asleep-awake (AA) technique, a variation of the AAA anesthesia technique, and the MAC, which consists of a sedation that makes it possible to control pain and anxiety. Unlike the AA technique, the MAC does not involve the use of invasive airway devices. Objective The main objective was to contrast the two anesthetic management techniques for awake brain surgery used in our hospital. Methods A retrospective observational single-center study was performed consisting of a review of patient clinical records. The study sample comprised all patients above 18 years of age undergoing brain surgery through awake craniotomy between January 2013 and December 2022 at the Miguel Servet University Hospital (HUMS) in Zaragoza (Spain). Results Of the 79 patients included in the study, 39 were operated under AA anesthesia while the remaining 40 were operated under the MAC procedure. The main age of the participants was 52.8 years, the mean height was 169 cm, and the mean weight was 74.2 kg. No statistically significant differences were observed with respect to the patients' baseline characteristics, except for obesity which was more prevalent in the MAC group. In the MAC group, the airway was managed by means of nasal cannulas in all cases, with conversion to general anesthesia being required in only one instance. In the AA group, the laryngeal mask (LM) was used in 89.7% of the patients, and the endotracheal tube (ETT) in 10.3%. The surgical and anesthetic procedure duration was 15 and 20 minutes shorter in the MAC group, respectively. A reduction of almost 20 minutes in the anesthetic procedure and 15 minutes in the surgical one was observed. Tachycardia, desaturation, and airway complications were observed in four, five, and four patients respectively in the AA group but in none of the patients in the MAC group. The mean stay in the intensive care unit (ICU) and the mean postoperative hemoglobin levels between both groups were insignificant. Conclusions Both techniques analyzed in this study turned out to be equally safe and effective for brain tumor surgery in awake patients.

Effect of dexmedetomidine on postoperative delirium in patients undergoing awake craniotomies: study protocol of a randomized controlled trial

INTRODUCTION

Postoperative delirium (POD) is a common complication, and it has a high incidence in neurosurgery patients. Awake craniotomy (AC) has been widely performed in patients with glioma in eloquent and motor areas. Most of the surgical procedure is frontotemporal craniotomy, and the operation duration has been getting longer. Patients undergoing AC are high-risk populations for POD. Dexmedetomidine (Dex) administration perioperatively might help to reduce the incidence of POD. The purpose of this study is to investigate the effect of Dex on POD in patients undergoing AC.

METHODS

The study is a prospective, single-center, double-blinded, paralleled-group, randomized controlled trial. Patients undergoing elective AC will be randomly assigned to the Dex group and the control group. Ten minutes before urethral catheterization, patients in the Dex group will be administered with a continuous infusion at a rate of 0.2 µg/kg/h until the end of dural closure. In the control group, patients will receive an identical volume of normal saline in the same setting. The primary outcome will be the cumulative incidence and severity of POD. It will be performed by using the confusion assessment method in the first 5 consecutive days after surgery. Secondary outcomes include quality of intraoperative awareness, stimulus intensity of neurological examination, pain severity, quality of recovery and sleep, and safety outcomes.

DISCUSSION

This study is to investigate whether the application of Dex could prevent POD in patients after undergoing AC and will provide strong evidence-based clinical practice on the impact of intraoperative interventions on preventing POD in AC patients.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05195034. Registered on January 18, 2022.

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.

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.

Comparison of dexmedetomidine and propofol for sedation in awake craniotomy: A meta-analysis

BACKGROUND

Awake craniotomy (AC) is the preferred option for the resection of tumors adjacent to eloquent cortical areas and in cases of intractable epilepsy. It is mostly used to maintain the integrity of the brain during intracranial neurosurgical procedures. Awake craniotomy requires the use of ideal anesthetics, hypnotics, and analgesics to balance sedation, prompt the reversal of sedation, and prevent respiratory depression while maintaining communication between patient and medical team. Although a wide variety of anesthetics and hypnotics have been used for awake craniotomy over the past several decades, the optimal drug for the procedure has yet to be determined. The purpose of this meta-analysis was to compare dexmedetomidine and propofol in terms of intraoperative adverse events (i.e., hypertension, hypotension, nausea, vomiting, respiratory depression), patient and surgeon satisfaction, and procedure duration.

METHODS

We searched PubMed, Google Scholar, and the Cochrane Library for relevant articles published between the inception of these databases and April of 2022. The systematic search yielded 781 articles. After screening, we excluded 778 articles. The remaining three articles reporting 138 patients were selected for meta-analysis.

RESULTS

This meta-analysis showed no statistically significant difference between propofol and dexmedetomidine related to intraoperative adverse events, patient satisfaction, or procedure duration. The only statistically significant result was surgeon satisfaction, which appeared to be higher in the dexmedetomidine group.

CONCLUSIONS

Further high-quality randomized and controlled trials are needed to find a preferred agent for intraoperative sedation in awake craniotomy.

Monitored Anesthesia Care Protocol for Awake Craniotomy and Patient's Perspective on the Procedure

OBJECTIVE

There is ongoing discussion on pros and cons in terms of different anesthesia protocols for awake craniotomy (AC) with direct brain stimulation. The aim of this study is to share our anesthesia protocol and present our patients' perspectives.

METHODS

We conducted an analysis of prospectively collected data from 53 (54 procedures) consecutive patients. Most of the patients (50) underwent surgery due to primary brain lesions. Eight procedures were performed in patients with lesions in the nondominant hemisphere for language. Four of all procedures were reoperations, and one patient was operated on in awake conditions twice. The psychological evaluation of patients was performed 2 times: 2 days before and after surgery. A visual analog scale for pain and stress levels as well as structured interviews was used.

RESULTS

Most patients tolerated ACwell. Patients reported that discomfort was mostly related to urinary catheter insertion, head holder placement, and temporal muscle detachment in cases of frontotemporal craniotomies. The intensity of stress measured with the visual analog scale before surgery was negatively associated with age and positively correlated with stress experienced in the operating room. In all patients, we were able to finish the procedure according to the monitored anesthesia care protocol without the need for conversion to general anesthesia. We observed 3 (5.6%) intraoperative seizures that required deepening of sedation.

CONCLUSION

AC using the monitored anesthesia care protocol was a safe and well-tolerated procedure with satisfactory patient experience. Extensive preoperative preparation should be considered a key part of the procedure.

Neurosurgical Anesthesia: Optimizing Outcomes with Agent Selection

Anesthesia in neurosurgery embodies a vital element in the development of neurosurgical intervention. This undisputed interest has offered surgeons and anesthesiologists an array of anesthetic selections to utilize, though with this allowance comes the equally essential requirement of implementing a maximally appropriate agent. To date, there remains a lack of consensus and official guidance on optimizing anesthetic choice based on operating priorities including hemodynamic parameters (e.g., CPP, ICP, MAP) in addition to the route of procedure and pathology. In this review, the authors detail the development of neuroanesthesia, summarize the advantages and drawbacks of various anesthetic classes and agents, while lastly cohesively organizing the current literature of randomized trials on neuroanesthesia across various procedures.

Monitored anesthesia care and asleep-awake-asleep techniques combined with multiple monitoring for resection of gliomas in eloquent brain areas: a retrospective analysis of 225 patients

BACKGROUND

Awake craniotomy (AC) has become gold standard in surgical resection of gliomas located in eloquent areas. The conscious sedation techniques in AC include both monitored anesthesia care (MAC) and asleep-awake-asleep (AAA). The choice of optimal anesthetic method depends on the preferences of the surgical team (mainly anesthesiologist and neurosurgeon). The aim of this study was to compare the difference in physiological and blood gas data, dosage of different drugs, the probability of switching to endotracheal intubation, and extent of tumor resection and dysfunction after operation between AAA and MAC anesthetic management for resection of gliomas in eloquent brain areas.

METHODS

Two-hundred and twenty-five patients with super-tentorial tumor located in eloquent areas underwent AC from 2009 to 2021 in Xijing Hospital. Forty-one patients underwent AAA technique, and the rest one-hundred eighty-four patients underwent MAC technique. Anesthetic management, dosage of different drugs, intraoperative complications, postoperative outcomes, adverse events, extent of resection and motor, and sensory and language dysfunction after operation were compared between MAC and AAA.

RESULT

There was no significant difference in gender, KPS score, MMSE score, glioma grade, type, and growth site between the patients in the two groups, except the older age of patients in MAC group than that in AAA group. During the whole process of operation, there were greater pulse pressure difference (P = 0.046), shorter operation time (P = 0.039), less dosage of remifentanil (P = 0.000), more dosage of dexmedetomidine (P = 0.013), more use of antiemetics (81%, P = 0.0067), lower use of vasoactive agent (45.1%, P = 0.010), and lower probability of conversion to general anesthesia (GA, P = 0.027) in MAC group than that in AAA group. Blood gas analysis showed that PetCO2 (P = 0.000), Glu concentration (P = 0.000), and PaCO2 (P = 0.000) were higher, but SPO2 (P = 0.002) and PaO2 (P = 0.000) were lower in MAC group than that in AAA group. In the postoperative recovery stage, compared with that of AAA group, the probability of dysfunction in MAC group at 1, 3, 5, and 7 days after operation was lower, which were 27.8% vs 53.6% (P = 0.003), 31% vs 68.3% (P = 0.000), 28.8% vs 63.4% (P = 0.000), and 25.6% vs 58.5% (P = 0.000), respectively.

CONCLUSION

Compared with AAA, it seems that MAC has more advantages in the management for resection of gliomas in eloquent brain areas, and MAC combined with multiple monitoring such as cerebral cortical mapping, neuronavigation, and ultrasonic detection is worthy of popularization for the resection of gliomas in eloquent brain areas.

Intraoperative radiotherapy during awake craniotomies: preliminary results of a single-center case series

Awake craniotomies are performed to avoid postoperative neurological deficits when resecting lesions in the eloquent cortex, especially the speech area. Intraoperative radiotherapy (IORT) has recently focused on optimizing the oncological treatment of primary malignant brain tumors and metastases. Herein, for the first time, we present preliminary results of IORT in the setting of awake craniotomies. From 2021 to 2022, all patients undergoing awake craniotomies for tumor resection combined with IORT were analyzed retrospectively. Demographical and clinical data, operative procedure, and treatment-related complications were evaluated. Five patients were identified (age (mean ± standard deviation (SD): 65 ± 13.5 years (y)). A solid left frontal metastasis was detected in the first patient (female, 49 y). The second patient (male, 72 y) presented with a solid metastasis on the left parietal lobe. The third patient (male, 52 y) was diagnosed with a left temporoparietal metastasis. Patient four (male, 74 y) was diagnosed with a high-grade glioma on the left frontal lobe. A metastasis on the left temporooccipital lobe was detected in the fifth patient (male, 78 y). After awake craniotomy and macroscopic complete tumor resection, intraoperative tumor bed irradiation was carried out with 50 kV x-rays and a total of 20 Gy for 16.7 ± 2.5 min. During a mean follow-up of 6.3 ± 2.6 months, none of the patients developed any surgery- or IORT-related complications or disabling permanent neurological deficits. Intraoperative radiotherapy in combination with awake craniotomy seems to be feasible and safe.

Supratotal Resection of Gliomas With Awake Brain Mapping: Maximal Tumor Resection Preserving Motor, Language, and Neurocognitive Functions

Gliomas are a category of infiltrating glial neoplasms that are often located within or near the eloquent areas involved in motor, language, and neurocognitive functions. Surgical resection being the first-line treatment for gliomas, plays a crucial role in patient outcome. The role of the extent of resection (EOR) was evaluated, and we reported significant correlations between a higher EOR and better clinical prognosis of gliomas. However, recurrence is inevitable, even after aggressive tumor removal. Thus, efforts have been made to achieve extended tumor resection beyond contrast-enhanced mass lesions in magnetic resonance imaging (MRI)-defined areas, a process known as supratotal resection. Since it has been reported that tumor cells invade beyond regions visible as abnormal areas on MRI, imaging underestimates the true spatial extent of tumors. Furthermore, tumor cells have the potential to spread 10–20 mm away from the MRI-verified tumor boundary. The primary goal of supratotal resection is to maximize EOR and prolong the progression-free and overall survival of patients with gliomas. The available data, as well as our own work, clearly show that supratotal resection of gliomas is a feasible technique that has improved with the aid of awake functional mapping using intraoperative direct electrical stimulation. Awake brain mapping has enabled neurosurgeons achieve supratotal resection with favorable motor, language, and neurocognitive outcomes, ensuring a better quality of life in patients with gliomas.

Benzodiazepine Sedation and Postoperative Neurological Deficits after Awake Craniotomy for Brain Tumor - An Exploratory Retrospective Cohort Study

An awake craniotomy is a common neurosurgical procedure for excising brain tumor(s) located near or in eloquent areas. The use of benzodiazepine (BZD) for sedation in some patients with neuropathological conditions (e.g., stroke, brain tumors) has been previously linked with re-appearance of neurological deficits including limb incoordination, ataxia, and motor weakness, resulting in complications for the patient along with procedural challenges. Whether or not these findings can be extrapolated to patients undergoing brain tumor resection is largely unknown. The current work primarily sought to compare neurological outcome(s) in the immediate postoperative period between BZD-free and BZD-based sedation techniques in patients undergoing awake craniotomy. Using a database composed of awake craniotomies conducted within a single center and by a single surgeon, patients were retrospectively classified based on midazolam administration into BZD-free sedation (n=125) and BZD-based sedation (n=416) groups. Patients from each group were matched based on age, sex, tumor location, tumor grade, preoperative neurological deficits, non-operative BZD use, and Karnofsky Performance Scale scores, resulting in 108 patients within each group. Postoperative neurological deficits were recorded. Logistic regression analyses were conducted comparing postoperative neurological deficits between the matched groups. Postoperative neurological deficits were more prevalent within the BZD-based sedation group compared to the BZD-free sedation group (adjusted odds ratio (aOR)=1.903, 95% CI=1.018-3.560, p=0.044). In addition, subgroup analysis of the matched cohort showed a relationship between preoperative neurological symptoms and postoperative neurological deficits in the BZD-based sedation group (aOR=3.756, 95% CI=1.390-10.147, p=0.009). Our findings support the notion that the increased incidence of postoperative neurological deficits with BZD sedation may in part be related to the unmasking of preoperative neurological deficits. Further studies are required to confirm this phenomenon.

Serum Concentration of Ropivacaine After Repeated Administration to Several Parts of the Head During Awake Craniotomy: A Prospective Cohort Study

Introduction

During awake craniotomy, effective use of local anesthetics, such as ropivacaine, is critical. Blood concentrations of ropivacaine after repeated administration over a short period during awake craniotomy have not been studied.

Materials and Methods

In this prospective cohort study, we evaluated serum concentrations of ropivacaine 15 min after each administration during awake craniotomy at Nagoya University Hospital between April 5, 2018 and August 31, 2019 to determine the safe dose. A total of 30 patients scheduled to undergo elective awake craniotomy were included. Patients were injected with 0.375% ropivacaine before the awake phase at the following points: scalp block (T1), headpin area (T2), skin incision area (T3), temporal muscle (T4), and dura mater (T5). Arterial blood samples were collected 15 min after ropivacaine administration. In addition to the blood concentrations of ropivacaine, complications during the awake phase were evaluated as secondary endpoints.

Results

The mean total dose of ropivacaine was 5.01 ± 0.68 mg/kg (maximum total dose: 6.30 mg/kg). The mean interval from T1 to T5 was 128.0 ± 17.7 min. The maximum serum concentration did not exceed the toxicity threshold of 4.3 μg/mL in any patient (mean serum concentration: T1, 1.23 ± 0.36 μg/mL; T5, 0.82 ± 0.26 μg/mL). No addiction symptoms were observed during awakening in any case.

Conclusion

Our results show that, in cases of awake craniotomy with repeated anesthetic administration, a total dose of up to 5.0 mg/kg is safe, without addiction symptoms. Relatively large amounts of ropivacaine can be safely injected during awake craniotomy.

Intraoperative Brain Mapping in Multilingual Patients: What Do We Know and Where Are We Going?

In this review, we evaluate the knowledge gained so far about the neural bases of multilingual language processing obtained mainly through imaging and electrical stimulation mapping (ESM). We attempt to answer some key questions about multilingualism in the light of recent literature evidence, such as the degree of anatomical–functional integration of two or more languages in a multilingual brain, how the age of L2-acquisition affects language organization in the human brain, or how the brain controls more than one language. Finally, we highlight the future trends in multilingual language mapping.

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.

Awake craniotomy with dexmedetomidine during resection of brain tumours located in eloquent regions

INTRODUCTION

An awake craniotomy (AC) is the gold standard for the resection of supra-tentorial brain tumours in eloquent areas. Intraoperative monitoring "on-demand" of essential eloquent brain functions and the increasing need to preserve higher intellectual functions during surgery requires a unique anaesthetic approach during AC. Dexmedetomidine is considered the first-choice pharmacological agent for sedation during AC.

MATERIAL AND METHODS

Twenty-six patients with a single brain tumour located in areas of eloquent brain function were enrolled in this prospective study. The patients underwent AC under conscious sedation. Motor-evoked potentials and brainstem-evoked auditory potentials were measured using neurophysiological tests during surgery to assess brain potentials. Intraoperative brain relaxation was reached using a modified Bristow scale. Neuromonitoring and psychological tests were maintained until meningeal closure.

RESULTS

All operations were carried out successfully, and no reoperations were needed. No significant impact on circulatory and respiratory parameters was observed during conscious sedation based on dexmedetomidine. Neither instrumental airway support nor conversion to general anaesthesia was necessary. Brain relaxation was good in 84% of cases. Intraoperative epileptic episodes were observed in 15% of the patients. Neuro-logical and psychological monitoring was satisfactory. Unaltered muscle force was observed postoperatively in 88% of the patients.

CONCLUSIONS

AC performed under conscious sedation, and dexmedetomidine infusion without instrumental airway support, was safe and well-tolerated by patients with comfortable physiological sleep for most of the procedure. This approach to AC was associated with minimal risk of perioperative adverse events and may be particularly beneficial in patients with severe comorbidities.

Predictors for time to awake in patients undergoing awake craniotomies

OBJECTIVE

Awake craniotomies are often characterized by alternating asleep-awake-asleep periods. Preceding the awake phase, patients are weaned from anesthesia and mechanical ventilation. Although clinicians aim to minimize the time to awake for patient safety and operating room efficiency, in some patients, the time to awake exceeds 20 minutes. The goal of this study was to determine the average time to awake and the factors associated with prolonged time to awake (> 20 minutes) in patients undergoing awake craniotomy.

METHODS

Records of patients who underwent awake craniotomy between 2003 and 2020 were evaluated. Time to awake was defined as the time between discontinuation of propofol and remifentanil infusion and the time of extubation. Patient and perioperative characteristics were explored as predictors for time to awake using logistic regression analyses.

RESULTS

Data of 307 patients were analyzed. The median (IQR) time to awake was 13 (10-20) minutes and exceeded 20 minutes in 17% (95% CI 13%-21%) of the patients. In both univariate and multivariable analyses, increased age, nonsmoker status, and American Society of Anesthesiologists (ASA) class III versus II were associated with a time to awake exceeding 20 minutes. BMI, as well as the use of alcohol, drugs, dexamethasone, or antiepileptic agents, was not significantly associated with the time to awake.

CONCLUSIONS

While most patients undergoing awake craniotomy are awake within a reasonable time frame after discontinuation of propofol and remifentanil infusion, time to awake exceeded 20 minutes in 17% of the patients. Increasing age, nonsmoker status, and higher ASA classification were found to be associated with a prolonged time to awake.

Intraoperative panic attack in patients undergoing awake craniotomy: a retrospective analysis of risk factors

PURPOSE

Intraoperative anxiety is the most common psychological response of the patient during awake craniotomy. Psychological stress can trigger patient decline, resulting in failed awake craniotomy and significantly poor outcomes. This study aimed to identify the risk factors for panic attack (PA) during awake craniotomies.

METHODS

With the local ethics committee approval, we conducted a manual chart review of the medical record of patients who underwent consecutive awake craniotomies between November 1999 and October 2016 at Tokyo Women's Medical University. A total of 405 patients were identified and assigned to 2 groups based on the Diagnostic and Statistical Manual of Mental Disorders-V criteria: those that met the PA criteria (Group PA) and those that did not (Group non-PA). Patient characteristics and the incidence of the PA specifier were collected. The features of the two groups were statistically compared, and risk factors for PA occurrence were determined by regression analysis.

RESULTS

Sixteen of 405 patients met the diagnostic criteria of PA. Patients' characteristics were not statistically different between the groups. Multivariate logistic regression showed that intraoperative anxiety (p = 0.0002) and age younger than 39 years (as opposed to age >  = 39 years; p = 0.0328) were significantly associated with the occurrence of PA during awake craniotomy.

CONCLUSIONS

For patients undergoing awake craniotomy, intraoperative anxiety and age younger than 39 years were considered risk factors of PA. As PA often necessitates conversion to general anesthesia, intensive perioperative psychological support and pain management are required to achieve patient satisfaction and the surgical goal of awake craniotomy.

Intraoperative Neuromonitoring During Resection of Gliomas Involving Eloquent Areas

In the case of resection of gliomas involving eloquent areas, equal consideration should be given to maintain maximal extent of resection (EOR) and neurological protection, for which the intraoperative neuromonitoring (IONM) proves an effective and admirable approach. IONM techniques applied in clinical practice currently consist of somatosensory evoked potential (SSEP), direct electrical stimulation (DES), motor evoked potential (MEP), electromyography (EMG), and electrocorticography (ECoG). The combined use of DES and ECoG has been adopted widely. With the development of technology, more effective IONM tactics and programs would be proposed. The ultimate goal would be strengthening the localization of eloquent areas and epilepsy foci, reducing the incidence of postoperative dysfunction and epilepsy improving the life quality of patients.

Awake surgery for lesions near eloquent brain under scalp block and clinical monitoring: experience of single center with limited resources

Background

Surgery of the brain tumors near eloquent areas carries the risk of either disabling neurological deficit or inadequate resection with bad prognosis in both situations. Awake surgery is the gold standard procedure for such lesions. However, it requires certain anesthetic drugs, advanced techniques, and trained teams that are not available in every neurosurgical institute. This work aims to evaluate safety, feasibility, and outcome of operating on patients with space occupying lesions near eloquent areas under scalp block being continuously examined by a neurologist through retrospective study of 20 cases with supratentorial lesions related to language or sensorimotor cortex.

Results

There were 12 males and 8 females with mean age 36.8 years. Forty percent of patients were presented by motor weakness. Tumors were related to motor cortex in 11 patients and to language areas in 9 patients. Mean operative time was 210 min. Gross or near total resection was achieved in 15cases, four cases had subtotal resection and biopsy only was done in 1 case. Two patients suffered from intraoperative seizures and conversion to general anesthesia was required in one patient.

Conclusion

Operating on tumors near eloquent brain areas under scalp block and continuous neurological examination during tumor resection proved to be effective in early detection and prevention of permanent major deficits especially in the developing countries with limited resources.

Awake craniotomy in brain tumors - Technique systematization and the state of the art

The anesthesia for awake craniotomy (AC) is a consecrated anesthetic technique that has been perfected over the years. Initially used to map epileptic foci, it later became the standard technique for the removal of glial neoplasms in eloquent brain areas. We present an AC anesthesia technique consisting of three primordial times, called awake-asleep-awake, and their respective particularities, as well as delve into the anesthetic medications used. Its use in patients with low and high-grade gliomas was favorable for the resection of tumors within the functional boundaries of patients, with shorter hospital stay and lower direct costs. The present study aims to systematize the technique based on the experience of the largest philanthropic hospital in Latin America and discusses the most relevant aspects that have consolidated this technique as the most appropriate in the surgery of gliomas in eloquent areas.

Pain Management Experiences Among Hospitalized Postcraniotomy Brain Tumor Patients

BACKGROUND

Brain tumors account for the majority of central nervous system tumors, and most are removed by craniotomies. Many postcraniotomy patients experience moderate or severe pain after surgery, but patient perspectives on their experiences with pain management in the hospital have not been well described.

OBJECTIVE

The aim of this study was to describe how patients who have undergone a craniotomy for brain tumor removal experience pain management while hospitalized.

METHODS

Qualitative descriptive methods using semistructured interviews were conducted with patients on a neurological step-down unit in an urban teaching hospital in the Midwest United States. Interviews focused on how patients experienced postcraniotomy pain and how it was managed. Narratives were analyzed with standard content analytic procedures.

RESULTS

Twenty-seven participants (median age, 58.5 years; interquartile range, 26-41 years; range, 21-83 years) were interviewed. The majority were white (n = 25) and female (n = 15) and had an anterior craniotomy (n = 25) with sedation (n = 17). Their pain experiences varied on 2 dimensions: salience of pain during recovery and complexity of pain management. Based on these dimensions, 3 distinct types of pain management experiences were identified: (1) pain-as-nonsalient, routine pain management experience; (2) pain-as-salient, routine pain management experience; and (3) pain-as-salient, complex pain management experience.

CONCLUSIONS

Many postcraniotomy patients experience their pain as tolerable and/or pain management as satisfying and effective; others experience pain and pain management as challenging.

IMPLICATIONS FOR PRACTICE

Clinicians should be attuned to needs of patients with complex pain management experiences and should incorporate good patient/clinician communication.

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.

Neurocognitive Impairment After Propofol With Relevance for Neurosurgical Patients and Awake Craniotomies-A Prospective Observational Study

Background: Short-acting anesthetics are used for rapid recovery, especially for neurological testing during awake craniotomy. Extent and duration of neurocognitive impairment are ambiguous.

Methods: Prospective evaluation of patients undergoing craniotomy for tumor resection during general anesthesia with propofol (N of craniotomies = 35). Lexical word fluency, digit span and trail making were tested preoperatively and up to 24 h after extubation. Results were stratified for age, tumor localization and hemisphere of surgery. Results in digit span test were compared to 21 patients during awake craniotomies.

Results: Word fluency was reduced to 30, 33, 47, and 87% of preoperative values 10, 30, 60 min and 24 h after extubation, respectively. Digit span was decreased to 41, 47, 55, and 86%. Performances were still significantly impaired 24 h after extubation, especially in elderly. Results of digit span test were not worse in patients with left hemisphere surgery. Significance of difference to baseline remained, when patients with left or frontal lesions, i.e., brain areas essential for these tests, were excluded from analysis. Time for trail making was increased by 87% at 1 h after extubation, and recovered within 24 h. In 21 patients undergoing awake craniotomies without pharmacological sedation, digit span was unaffected during intraoperative testing.

Conclusion: Selected aspects of higher cognitive functions are compromised for up to 24 h after propofol anesthesia for craniotomy. Propofol and the direct effects of surgical resection on brain networks may be two major factors contributing (possibly jointly) to the observed deficits. Neurocognitive testing was unimpaired in patients undergoing awake craniotomies without sedation.

Choosing Neuroanaesthesia as a career: Marching towards new horizons

Anaesthesiology is an ever-changing science and amongst its sub-specialities, the field of neuroanaesthesia is making rapid strides. The fragility of the brain and spinal cord and the multitude of complexities involved in neurosurgery and interventional neuroradiological procedures demand dedicated training in neuroanaesthesia. With rapid advancement in other neuroscience specialties, neuroanaesthesia too has made outstanding progress, owing to establishment of structured training, publication of high-quality scientific research, and invention of novel medications and monitoring modalities. The opportunities for training in India and abroad and resources to broaden knowledge in neuroanaesthesia have increased over the last two decades. A career in neuroanaesthesia offers a great future for budding anaesthesiologists.

Awake Craniotomy and Memory Induction Through Electrical Stimulation: Why Are Penfield's Findings Not Replicated in the Modern Era?

From the 1930s through the early 1960s, Wilder Penfield12 collected a large number of memories induced by electrical brain stimulation (EBS) during awake craniotomy. As a result, he was a major contributor to several neuroscientific and neuropsychological concepts of long-term memory. His 1963 paper, which recorded all the cases of memories he induced in his operating room, remains a substantial point of reference in neuroscience in 2019, although some of his interpretations are now debatable.  However, it is highly surprising that, since Penfield's12 reports, there has been no other surgical publication on memories induced during awake surgery. In this review, we explore this phenomenon and analyze some of the reasons that might explain it. We hypothesize that the main reasons for lack of subsequent reports are related to changes in operative procedures (ie, use of anesthetics, time constraints, and insufficient debriefings) and changes in EBS parameters, rather than to the sites that are stimulated, the pathology treated, or the tasks used. If reminiscences are still induced, they should be reported in detail to add valuable contributions to the understanding of long-term memory networks, especially memories that are difficult to reproduce in the laboratory, such as autobiographical memories.

Experience with awake throughout craniotomy in tumour surgery: technique and outcomes of a prospective, consecutive case series with patient perception data

BACKGROUND

Awake craniotomy is the standard of care in surgery of tumours located in eloquent parts of the brain. However, high variability is recorded in multiple parameters, including anaesthetic techniques, mapping paradigms and technology adjuncts. The current study is focused primarily on patients' level of consciousness, surgical technique, and experience based on a cohort of 50 consecutive cases undergoing awake throughout craniotomy (ATC).

METHODS

Data was collected prospectively for 46 patients undergoing 50 operations over 14-month period, by the senior author, including demographics, extent of resection (EOR), adverse intraoperative events, surgical morbidity, surgery duration, levels of O₂ saturation and brain oedema. A prospective, patient experience questionnaire was delivered to 38 patients.

RESULTS

The ATC technique was well tolerated in all patients. Once TCI stopped, all patients were immediately assessable for mapping. Despite > 75% of cases being considered inoperable/high risk, gross total resection (GTR) was achieved in 68% patients and subtotal resection in 20%. The average duration of surgery was 220 min with no episodes of hypoxia. Early and late severe deficits recorded in 12% and 2%, respectively. No stimulation-induced seizures or failed ATCs were recorded. Patient-recorded data showed absent/minimal pain during (1) clamp placement in 95.6% of patients; (2) drilling in 94.7% of patients; (3) surgery in 78.9% of patients. Post-operatively, 92.3% of patients reported willingness to repeat the ATC, if necessary.

CONCLUSIONS

The current ATC paradigm allows immediate brain mapping, maximising patient comfort during self-positioning. Despite the cohort of challenging tumour location, satisfactory EOR was achieved with acceptable morbidity and no adverse intraoperative events.

Awake Craniotomy in Low-Resource Settings: Findings from a Retrospective Cohort in the Philippines

BACKGROUND

Awake craniotomy is a technique used to maximize resection of lesions in eloquent areas of the brain and preserve function. Although its use in high-income centers is well documented for tumors and vascular lesions, reports of its use in low-middle-income countries are limited. There are no published series from the Philippines.

METHODS

We performed a retrospective review of all patients who underwent awake craniotomy at a tertiary referral center in Manila, Philippines from 2010 to 2019. Data on demographics, clinical features, diagnoses, intraoperative and postoperative complications, and outcomes were collected. Regression analyses were performed to correlate use of intraoperative adjuncts with outcome measures (extent of resection, complication rate, neurologic status after surgery and on last follow-up, and in-hospital mortality).

RESULTS

A total of 65 patients were included in the cohort, who had a male predilection (60%) and a mean age at diagnosis of 40.4 years. The most common indication was tumor excision (90%), followed by excision of arteriovenous malformations (5%) and cavernomas (3%). Of the tumors, the most common histopathologic diagnosis was low-grade glioma (48%). The intraoperative complication rate was 13.8%, with the most common complication being patient intolerance. Gross total excision rate for tumors was 78.3%. Univariate analysis showed that use of a cortical stimulator was associated with improved neurologic status on last follow-up (P = 0.0471).

CONCLUSIONS

Our experience shows that awake craniotomy is feasible in low-middle-income country settings and is safe and effective for excision of tumors, arteriovenous malformations, and cavernomas.

Emergency Airway Management During Awake Craniotomy: Comparison of 5 Techniques in a Cadaveric Model

BACKGROUND

During awake craniotomy, securing the patient's airway might be necessary electively or emergently. The objective of this study was to compare the feasibility of airway management using a laryngeal mask airway (LMA) and 4 alternative airway management techniques in an awake craniotomy simulation.

METHODS

After completing a questionnaire, 9 anesthesia providers attempted airway management in a cadaver positioned to simulate awake craniotomy conditions. Following the simulation, participants rated and ranked the devices in their order of preference.

RESULTS

Only 3 approaches resulted in the successful securement of an airway device for 100% of participants: LMA (median; interquartile range time to secure the airway 6 s, 5 to 10 s), fiberoptic bronchoscopy through an LMA (41 s; 23 to 51 s), and video laryngoscopy (49 s; 43 to 127 s). In contrast, the oral and nasal fiberoptic approaches demonstrated only 44.4% (154.5 s; 134.25 to 182 s) and 55.6% (75 s; 50 to 117 s) success rates, respectively. The LMA was the fastest and most reliable primary method to secure the airway (P=0.001). After the simulation, 100% of participants reported that an LMA would be their first choice for emergency airway management, followed by fiberoptic intubation through the LMA (7 of 9 participants) if the LMA failed to properly seat.

CONCLUSIONS

We demonstrated that an LMA was the fastest and most reliable primary method to secure an airway in a laterally positioned cadaver with 3-pin skull fixation. Fiberoptic and video laryngoscope airway equipment should be readily available during awake craniotomy procedures, and an attempt to visualize the vocal cords through the LMA should be attempted before removing it for alternative techniques.

Anesthetic considerations for awake craniotomy

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