Anesthesia for awake craniotomy: a how-to guide for the occasional practitioner

Prospective Randomized Controlled Trial Comparing Anesthetic Management With Remimazolam Besylate and Flumazenil Versus Propofol During Awake Craniotomy Following an Asleep-awake-asleep Method

BACKGROUND

Awake craniotomy is performed to resect brain tumors in eloquent brain areas to maximize tumor reduction and minimize neurological damage. Evidence suggests that intraoperative anesthetic management of awake craniotomy with remimazolam is safe. We compared the time to arousal and efficacy of anesthetic management with remimazolam and propofol during awake craniotomy.

METHODS

In a single-institution randomized, prospective study, patients who underwent elective awake craniotomy were randomized to receive remimazolam and reversal with flumazenil (group R) or propofol (group P). The primary end point was time to awaken. Secondary end points were time to loss of consciousness during induction of anesthesia, the frequency of intraoperative complications (pain, hypertension, seizures, nausea, vomiting, and delayed arousal), and postoperative nausea and vomiting. Intraoperative task performance was assessed using a numerical rating scale (NRS) score.

RESULTS

Fifty-eight patients were recruited, of which 52 (26 in each group) were available for the efficacy analysis. Patients in group R had faster mean (±SD) arousal times than those in the P group (890.8±239.8 vs. 1075.4±317.5 s; P=0.013)and higher and more reliable intraoperative task performance (NRS score 8.81±1.50 vs. 7.69±2.36; P=0.043). There were no significant intraoperative complications.

CONCLUSIONS

Compared with propofol, remimazolam was associated with more rapid loss of consciousness and, after administration of flumazenil, with faster arousal times and improved intraoperative task performance.

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.

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.

Anesthesia for awake craniotomy: a case report

Awake craniotomy (AC) is a neurosurgical technique that enables the precise localization of functional neural networks through intraoperative brain mapping and real-time monitoring. This operative method has been popularized in recent years due to decreased postoperative morbidities. We present a case of 31-year-old female who was presented with episodes of generalized tonic colonic seizures. She had a history of recurring seizures. Upon further investigations, she was diagnosed with brain space-occupying lesions initially suspected as low-grade glioma. Considering the lesion site, the patient was deemed a suitable candidate for an AC. To achieve conscious sedation, the patient received infusions of remifentanil and propofol at varying rates. During the procedure, the patient was under sedation and was regularly tested for response to predetermined commands. The tumor was successfully excised by using a combination of local anesthesia on the scalp and by the administration of propofol and boluses through a systemic infusion.

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.

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.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Patient-reported intraoperative experiences during awake craniotomy for brain tumors: a scoping review

Awake craniotomy (AC) is a neurosurgical procedure that may be used to excise tumors located in eloquent areas of the brain. The techniques and outcomes of AC have been extensively described, but data on patient-reported experiences are not as well known. To determine these, we performed a scoping review of patient-reported intraoperative experiences during awake craniotomy for brain tumor resection. A total of 21 articles describing 534 patients were included in the review. Majority of the studies were performed on adult patients and utilized questionnaires and interviews. Some used additional qualitative methodology such as grounded theory and phenomenology. Most of the evaluation was performed within the first 2 weeks post-operatively. Recollection of the procedure ranged from 0 to 100%, and most memories dealt with the cranial fixation device application, cranial drilling, and intraoperative mapping. All patients reported some degree of pain and discomfort, mainly due to the cranial fixation device and uncomfortable operative position. Most patients were satisfied with their AC experience. They felt that participating in AC gave them a sense of control over their disease and thought that trust in the treatment team and adequate pre-operative preparation were very important. Patients who underwent AC for brain tumor resection had both positive and negative experiences intraoperatively, but overall, majority had a positive perception of and high levels of satisfaction with AC. Successful AC depends not only on a well-conducted intraoperative course, but also on adequate pre-operative information and patient preparation.

Severe gastric insufflation and consequent atelectasis caused by gas leakage using AIR-Q laryngeal mask airway: A case report

BACKGROUND

The airways of patients undergoing awake craniotomy (AC) are considered “predicted difficult airways”, inclined to be managed with supraglottic airway devices (SADs) to lower the risk of coughing or gagging. However, the special requirements of AC in the head and neck position may deteriorate SADs’ seal performance, which increases the risks of ventilation failure, severe gastric insufflation, regurgitation, and aspiration.

CASE SUMMARY

A 41-year-old man scheduled for AC with the asleep–awake–asleep approach was anesthetized and ventilated with a size 3.5 AIR-Q intubating laryngeal mask airway (LMA). Air leak was noticed with adequate ventilation after head rotation for allowing scalp blockage. Twenty-five minutes later, the LMA was replaced by an endotracheal tube because of a change in the surgical plan. After surgery, the patient consistently showed low tidal volume and was diagnosed with gastric insufflation and atelectasis using computed tomography.

CONCLUSION

This case highlights head rotation may cause gas leakage, severe gastric insufflation, and consequent atelectasis during ventilation with an AIR-Q intubating laryngeal airway.

The Effects of Anesthetics on Glioma Progression: A Narrative Review

There are many established factors that influence glioma progression, including patient age, grade of tumor, genetic mutations, extent of surgical resection, and chemoradiotherapy. Although the exposure time to anesthetics during glioma resection surgery is relatively brief, the hemodynamic changes involved and medications used, as well as the stress response throughout the perioperative period, may also influence postoperative outcomes in glioma patients. There are numerous studies that have demonstrated that choice of anesthesia influences non-brain cancer outcomes; of particular interest are those describing that the use of total intravenous anesthesia may yield superior outcomes compared with volatile agents in in vitro and human studies. Much remains to be discovered on the topic of anesthesia's effect on glioma progression.

Awake Craniotomy Under 3-Tesla Intraoperative Magnetic Resonance Imaging: A Retrospective Descriptive Report and Canadian Institutional Experience

BACKGROUND

The role of high-field 3-Tesla intraoperative magnetic resonance imaging (I-MRI) during awake craniotomy (AC) has not been extensively studied. We report the feasibility and safety of AC during 3-Tesla I-MRI.

METHODS

This retrospective descriptive report compared 3 groups: AC with minimal sedation and I-MRI; I-MRI-guided craniotomy under general anesthesia (GA), and; AC without I-MRI. Perioperative factors, surgical, anesthetic and radiologic complications, and postoperative morbidity and mortality were recorded.

RESULTS

Overall, 85 patients are included in this report. Five of 23 patients (22%) who underwent AC with I-MRI had anesthetic complications (nausea/vomiting and conversion to GA) compared with 3 of 40 (8%) who underwent I-MRI-guided craniotomy under GA (nausea/vomiting during extubation, and arrhythmia). Intraoperative surgical complications (seizures and speech deficits) occurred in 5 patients (22%) who underwent AC and I-MRI, excessive intraoperative bleeding occurred in 2 patients (5%) who had I-MRI-guided craniotomy under GA, and 4 of 22 (18%) patients who underwent AC without I-MRI experienced neurological complications (seizures, motor deficits, and transient loss of consciousness). Eight patients (20%) who had I-MRI with GA had postoperative complications, largely neurological. The duration of surgery and anesthesia were shortest in the group of patients receiving AC without I-MRI. Seventy-three percent of the patients in this group had residual tumor postoperatively compared with 44% and 38% in those having I-MRI with AC or GA, respectively. Patients who underwent I-MRI-guided craniotomy with GA had the highest morbidity (8%) at hospital discharge.

CONCLUSIONS

Our institutional experience suggests that AC under 3-Tesla I-MRI could be an option for glioma resection, although firm conclusions cannot be drawn given the limited and heterogenous nature of our data. Future multicenter trials comparing anesthetic and imaging modalities for glioma resection are recommended.

Investigation of Asleep versus Awake Motor Mapping in Resective Brain Surgery

OBJECTIVE

To develop an asleep motor mapping paradigm for accurate detection of the corticospinal tract during glioma surgery and compare outcomes with awake patients undergoing glioma resection.

METHODS

A consecutive cohort of adult patients undergoing craniotomy for suspected diffuse glioma with tumor in a perirolandic location who had awake or asleep cortical and subcortical motor mapping with positive areas of motor stimulation were assessed for postoperative extent of resection (EOR), permanent neurological deficit, and proximity of stimulation to diffusion tensor imaging-based corticospinal tract depiction on preoperative magnetic resonance imaging. Outcome data were compared between asleep and awake groups.

RESULTS

In the asleep group, all 16 patients had improved or no change in motor function at last follow-up (minimum 3 months of follow-up). In the awake group, all 23 patients had improved function or no change at last follow-up. EOR was greater in the asleep group (mean [SD] EOR 88.71% [17.56%]) versus the awake group (mean [SD] EOR 80.62% [24.44%]), although this difference was not statistically significant (P = 0.3802). Linear regression comparing distance from stimulation to corticospinal tract in asleep (n = 14) and awake (n = 4) patients was r = -0.3759, R² = 0.1413, P = 0.1853, and 95% confidence interval = -0.4453 to 0.09611 and r = 0.7326, R² = 0.5367, P = 0.2674, and 95% confidence interval = -7.042 to 14.75, respectively.

CONCLUSION

In this small patient series, asleep motor mapping using commonly available motor evoked potential hardware appears to be safe and efficacious in regard to EOR and functional outcomes.

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.

Clinical applications of neurolinguistics in neurosurgery

The protection of language function is one of the major challenges of brain surgery. Over the past century, neurosurgeons have attempted to seek the optimal strategy for the preoperative and intraoperative identification of language-related brain regions. Neurosurgeons have investigated the neural mechanism of language, developed neurolinguistics theory, and provided unique evidence to further understand the neural basis of language functions by using intraoperative cortical and subcortical electrical stimulation. With the emergence of modern neuroscience techniques and dramatic advances in language models over the last 25 years, novel language mapping methods have been applied in the neurosurgical practice to help neurosurgeons protect the brain and reduce morbidity. The rapid advancements in brain-computer interface have provided the perfect platform for the combination of neurosurgery and neurolinguistics. In this review, the history of neurolinguistics models, advancements in modern technology, role of neurosurgery in language mapping, and modern language mapping methods (including noninvasive neuroimaging techniques and invasive cortical electroencephalogram) are presented.

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.

Head Rotation Reduces Oropharyngeal Leak Pressure of the i-gel and LMA® Supreme™ in Paralyzed, Anesthetized Patients: A Randomized Trial

BACKGROUND

Second-generation supraglottic airway (SGA) devices are useful for airway management during positive pressure ventilation in general anesthesia and emergency medicine. In some clinical settings, such as the anesthetic management of awake craniotomy, SGAs are used in the head-rotated position, which is required for exposure of the surgical field, although this position sometimes worsens the efficiency of mechanical ventilation with SGAs. In this study, we investigated and compared the influence of head rotation on oropharyngeal leak pressures (OPLP) of the i-gel and LMA® Supreme™, which are second-generation SGA devices.

METHODS

Patients who underwent elective surgery under general anesthesia were enrolled in this study and randomly divided into i-gel or LMA Supreme groups. After induction of anesthesia with muscle relaxation, the i-gel or LMA Supreme was inserted according to computerized randomization. The primary outcome was the OPLP at 0°, 30°, and 60° head rotation. The secondary outcomes were the maximum airway pressure and expiratory tidal volume when patients were mechanically ventilated using a volume-controlled ventilation mode with a tidal volume of 10 mL/kg (ideal body weight), ventilation score, and fiber-optic views of vocal cords.

RESULTS

Thirty-four and 36 participants were included in the i-gel and LMA Supreme groups, respectively. The OPLPs of the i-gel and LMA Supreme significantly decreased as the head rotation angle increased (mean difference [95% confidence interval], P value: i-gel; 0° vs 30°: 3.5 [2.2-4.8], P < .001; 30° vs 60°: 2.0 [0.6-3.5], P = .002; 0° vs 60°: 5.5 [3.3-7.8], P < .001, LMA Supreme; 0° vs 30°: 4.1 [2.6-5.5], P < .001; 30° vs 60°: 2.4 [1.1-3.7], P < .001; 0° vs 60°: 6.5 [5.1-8.0], P < .001). There were statistically significant differences in expiratory tidal volume and ventilation score between 0° and 60° in the i-gel group and in ventilation score between 30° and 60° in the LMA Supreme group. There was no statistically significant difference between the 2 devices in all outcome measures. The incidences of adverse events, such as hoarseness or sore throat, were not significantly different between i-gel and LMA Supreme.

CONCLUSIONS

Head rotation to 30° and 60° reduces OPLP with both i-gel and LMA Supreme. There is no difference in OPLP between i-gel and LMA Supreme in the 3 head rotation positions.

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.

Comparing two airway management strategies for moderately sedated patients undergoing awake craniotomy: A single-blinded randomized controlled trial

BACKGROUND

In the monitored anesthesia care (MAC) setting for awake craniotomy (AC), maintaining airway patency in sedated patients remains challenging. This randomized controlled trial aimed to compare the validity of the below-epiglottis transnasal tube insertion (the tip of the tube placed between the epiglottis and vocal cords) and the nasopharyngeal airway (simulated by the above-epiglottis transnasal tube with the tip of the tube placed between the epiglottis and the free edge of the soft palate) with respect to maintaining upper airway patency for moderately sedated patients undergoing AC.

METHODS

Sixty patients scheduled for elective AC were randomized to receive below-epiglottis (n = 30) or above-epiglottis (n = 30) transnasal tube insertion before surgery. Moderate sedation was maintained in the pre- and post-awake phases. The primary outcome was the upper airway obstruction (UAO) remission rate (relieved obstructions after tube insertion/the total number of obstructions before tube insertion).

RESULTS

The UAO remission rate was higher in the below-epiglottis group [100% (12/12) vs 45% (5/11); P = .005]. The tidal volume values monitored through the tube were greater in the below-epiglottis group during the pre-awake phase (P < .001). End-tidal carbon dioxide (EtCO₂ ) monitored through the tube was higher in the below-epiglottis group at bone flap removal (P < .001). During the awake phase, patients' ability to speak was not impeded. No patient had serious complications related to the tube.

CONCLUSION

The below-epiglottis tube insertion is a more effective method to maintain upper airway patency than the nasopharyngeal airway for moderately sedated patients undergoing AC.

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.

Indian Society of Neuroanaesthesiology and Critical Care (ISNACC) Position Statement and Advisory for the Practice of Neuroanesthesia during COVID-19 Pandemic

The coronavirus disease 2019 (COVID-19) is a major health emergency in today’s time. In December 2019, a cluster of pneumonia cases in Wuhan, China was attributed to a novel coronavirus. The World Health Organization declared it as a pandemic. As the majority of the cases suffering from COVID-19 are mildly symptomatic or asymptomatic, it becomes a great challenge to identify the infected persons in the absence of extensive testing. In the hospital environment, it can infect several other vulnerable patients and healthcare providers, significantly impacting the hospital services. Anesthesiologists are at an increased risk of COVID-19 transmission from the patients, as they are frequently involved in several aerosol-generating procedures. It is not possible to identify asymptomatic COVID-19 patients solely based on history-taking during their first point of contact with the anesthesiologists at the preanesthetic checkup clinic.

Most of the neurosurgical conditions are of urgent in nature and cannot be postponed for a longer duration. In view of this, the position statement and practice advisory from the Indian Society of Neuroanaesthesiology and Critical Care (ISNACC) provides guidance to the practice of neuroanesthesia in the present scenario. The advisory has been prepared considering the current disease status of the COVID-19 pandemic, available literature, and consensus from experts in the field of neuroanesthesiology. Since the pandemic is still progressing and the nature of the disease is dynamic, readers are advised to constantly look for updated literature from ISNACC and other neurology and neurosurgical societies.

Anesthesia management for low-grade glioma awake surgery: a European Low-Grade Glioma Network survey

BACKGROUND

Awake surgery has become a key treatment of diffuse low-grade gliomas (DLGG) and is divided in three main phases: opening, tumor resection - during which the patient needs to be fully awake - and closure. The anesthetic management of awake neurosurgery is a challenge, and there are currently no guidelines.

OBJECTIVE

The objective of the survey was to explore differences and commonalities regarding the anesthetic management of awake DLGG surgery within the European Low-Grade Glioma Network (ELGGN) centers.

METHODS

A form that contained 14 questions about the anesthetic management was sent to 28 centers in May 2015.

RESULTS

Twenty centers responded. During the opening and closing non-awake periods, 56% of teams chose general anesthesia with mechanical ventilation for at least one period (asleep-awake-asleep, SAS protocol), and 44% monitored anesthesia care including sedation without mechanical ventilation (MAC protocol). In case of SAS, all the teams chose intravenous anesthesia, 82% used laryngeal mask instead of endotracheal intubation during the opening sequence, and 71% during closure. Local and regional anesthesia was practiced by all the teams. The most frequently reported cause of pain was dural and cerebral vessels manipulation (77%). Pain management was mostly based on paracetamol (70%) and remifentanil (55%).

CONCLUSION

Our survey showed that there was an equivalent proportion of centers using SAS or MAC protocols in the anesthetic management of awake surgery in ELGGN centers. The advantages and disadvantages of each anesthesia protocol were reviewed.

Effects of low-dose remifentanil infusion on analgesic or antiemetic requirement during brain function mapping: A retrospective cohort study

BACKGROUND

Pain and discomfort during the awake phase in awake craniotomy should be relieved to facilitate brain mapping. Although some anaesthesiologists use low-dose (0.01-0.05 µg/kg/min) remifentanil infusion to provide analgesia during this phase, its efficacy and side effects have never been evaluated. Therefore, this study primarily aimed to investigate the effects of low-dose remifentanil infusion on the need for antiemetic treatment during brain mapping and secondarily aimed to determine its effects on the need for additional analgesic treatment.

METHODS

This retrospective study included 218 patients who underwent awake craniotomy at our centre from 2008 to 2018. The relationship between low-dose remifentanil infusion during the awake phase and the requirement for analgesic or antiemetic treatment was examined. A multivariable competing risk regression analysis was performed to adjust for patient and operative variables.

RESULTS

Sixty-six patients (30.3%) received low-dose (median rate: 0.01 µg/kg/min) remifentanil infusion during the awake phase. Forty-nine patients (22.5%) received an antiemetic and 99 (45.4%) received additional analgesic treatment. The difference in additional analgesic treatment was not significant between patients who received low-dose remifentanil infusion and those who did not (adjusted hazard ratio: 1.13; 95% confidence interval: 0.75-1.70; P = .570); however, the use of antiemetics significantly increased in patients who received remifentanil (adjusted hazard ratio: 1.78; 95% confidence interval: 1.01-3.15; P = .047).

CONCLUSION

Low-dose remifentanil infusion during the awake phase in awake craniotomy significantly increased the need for antiemetics but did not decrease the need for additional analgesic treatment.

Neuroanesthesia Practice During the COVID-19 Pandemic: Recommendations From Society for Neuroscience in Anesthesiology and Critical Care (SNACC)

The pandemic of coronavirus disease 2019 (COVID-19) has several implications relevant to neuroanesthesiologists, including neurological manifestations of the disease, impact of anesthesia provision for specific neurosurgical procedures and electroconvulsive therapy, and health care provider wellness. The Society for Neuroscience in Anesthesiology and Critical Care appointed a task force to provide timely, consensus-based expert guidance for neuroanesthesiologists during the COVID-19 pandemic. The aim of this document is to provide a focused overview of COVID-19 disease relevant to neuroanesthesia practice. This consensus statement provides information on the neurological manifestations of COVID-19, advice for neuroanesthesia clinical practice during emergent neurosurgery, interventional radiology (excluding endovascular treatment of acute ischemic stroke), transnasal neurosurgery, awake craniotomy and electroconvulsive therapy, as well as information about health care provider wellness. Institutions and health care providers are encouraged to adapt these recommendations to best suit local needs, considering existing practice standards and resource availability to ensure safety of patients and providers.

Setup presentation and clinical outcome analysis of treating highly language-eloquent gliomas via preoperative navigated transcranial magnetic stimulation and tractography

OBJECTIVE Awake surgery combined with intraoperative direct electrical stimulation (DES) and intraoperative neuromonitoring (IONM) is considered the gold standard for the resection of highly language-eloquent brain tumors. Different modalities, such as functional magnetic resonance imaging (fMRI) or magnetoencephalography (MEG), are commonly added as adjuncts for preoperative language mapping but have been shown to have relevant limitations. Thus, this study presents a novel multimodal setup consisting of preoperative navigated transcranial magnetic stimulation (nTMS) and nTMS-based diffusion tensor imaging fiber tracking (DTI FT) as an adjunct to awake surgery. METHODS Sixty consecutive patients (63.3% men, mean age 47.6 ± 13.3 years) suffering from highly language-eloquent left-hemispheric low- or high-grade glioma underwent preoperative nTMS language mapping and nTMS-based DTI FT, followed by awake surgery for tumor resection. Both nTMS language mapping and DTI FT data were available for resection planning and intraoperative guidance. Clinical outcome parameters, including craniotomy size, extent of resection (EOR), language deficits at different time points, Karnofsky Performance Scale (KPS) score, duration of surgery, and inpatient stay, were assessed. RESULTS According to postoperative evaluation, 28.3% of patients showed tumor residuals, whereas new surgery-related permanent language deficits occurred in 8.3% of patients. KPS scores remained unchanged (median preoperative score 90, median follow-up score 90). CONCLUSIONS This is the first study to present a clinical outcome analysis of this very modern approach, which is increasingly applied in neurooncological centers worldwide. Although human language function is a highly complex and dynamic cortico-subcortical network, the presented approach offers excellent functional and oncological outcomes in patients undergoing surgery of lesions affecting this network.

Combined use of minimal access craniotomy, intraoperative magnetic resonance imaging, and awake functional mapping for the resection of gliomas in 61 patients

OBJECTIVE

Current management of gliomas involves a multidisciplinary approach, including a combination of maximal safe resection, radiotherapy, and chemotherapy. The use of intraoperative MRI (iMRI) helps to maximize extent of resection (EOR), and use of awake functional mapping supports preservation of eloquent areas of the brain. This study reports on the combined use of these surgical adjuncts.

METHODS

The authors performed a retrospective review of patients with gliomas who underwent minimal access craniotomy in their iMRI suite (IMRIS) with awake functional mapping between 2010 and 2017. Patient demographics, tumor characteristics, intraoperative and postoperative adverse events, and treatment details were obtained. Volumetric analysis of preoperative tumor volume as well as intraoperative and postoperative residual volumes was performed.

RESULTS

A total of 61 patients requiring 62 tumor resections met the inclusion criteria. Of the tumors resected, 45.9% were WHO grade I or II and 54.1% were WHO grade III or IV. Intraoperative neurophysiological monitoring modalities included speech alone in 23 cases (37.1%), motor alone in 24 (38.7%), and both speech and motor in 15 (24.2%). Intraoperative MRI demonstrated residual tumor in 48 cases (77.4%), 41 (85.4%) of whom underwent further resection. Median EOR on iMRI and postoperative MRI was 86.0% and 98.5%, respectively, with a mean difference of 10% and a median difference of 10.5% (p < 0.001). Seventeen of 62 cases achieved an increased EOR > 15% related to use of iMRI. Seventeen (60.7%) of 28 low-grade gliomas and 10 (30.3%) of 33 high-grade gliomas achieved complete resection. Significant intraoperative events included at least temporary new or worsened speech alteration in 7 of 38 cases who underwent speech mapping (18.4%), new or worsened weakness in 7 of 39 cases who underwent motor mapping (18.0%), numbness in 2 cases (3.2%), agitation in 2 (3.2%), and seizures in 2 (3.2%). Among the patients with new intraoperative deficits, 2 had residual speech difficulty, and 2 had weakness postoperatively, which improved to baseline strength by 6 months.

CONCLUSIONS

In this retrospective case series, the combined use of iMRI and awake functional mapping was demonstrated to be safe and feasible. This combined approach allows one to achieve the dual goals of maximal tumor removal and minimal functional consequences in patients undergoing glioma resection.

Anesthesia for awake craniotomy

PURPOSE OF REVIEW

The current review reports on current trends in the anesthetic management of awake craniotomy, including preoperative preparation, sedation schemes, pain management, and prevention of intraoperative complications.

RECENT FINDINGS

Both approaches for anesthesia for awake craniotomy, asleep-awake-asleep and monitored anesthesia care (MAC), have shown equal efficacy for performing intraoperative brain mapping. Choice of the appropriate scheme is currently based mainly on the preferences of the particular anesthesiologist. Dexmedetomidine has demonstrated high efficacy and safety in MAC for awake craniotomy and has become a rational alternative to propofol. Despite the high efficacy of scalp block and opioids, pain remains a common compliant in awake craniotomy. Appropriate surgical tactics can reduce pain and even prevent postoperative neurological complications. Although the efficacy of prophylaxis of intraoperative seizures with anticonvulsants remains doubtful, levetiracetam can be superior to other drugs for this purpose.

SUMMARY

Following a great deal of progress in anesthetic management, awake craniotomy, which had been a relatively rare approach, is now a commonly performed procedure for neurosurgical intervention. Modern anesthesia techniques can provide for successful brain mapping in almost any patient. Management of awake craniotomy in high-risk patients is a central task for future research.

Nasotracheal intubation-extubation-intubation and asleep-awake-asleep anesthesia technique for deep brain stimulation

BACKGROUND

The asleep-awake-asleep (AAA) technique and laryngeal mask airway (LMA) is a common general anesthesia technique for deep brain stimulation (DBS) surgery. However, the LMA is not always the ideal artificial airway. In this report, we presented our experiences with nasotracheal intubation-extubation-intubation (IEI) and AAA techniques in DBS surgery for Parkinson's disease (PD) patients to meet the needs of surgery and ensure patients' safety and comfort.

CASE PRESENTATION

Three PD patients scheduled for DBS surgery had to receive general anesthesia for various reasons. For the first asleep stage, general anesthesia and nasotracheal intubation was completed with routine methods. During the awake stage, we pulled the nasotracheal tube back right above the epiglottis under fiberoptic bronchoscope (FOB) guidance for microelectrode recording (MER), macrostimulation testing and verbal communication. Once monitoring is completed, we induced anesthesia with rapid sequence induction and utilized the FOB to advance the nasotracheal tube into the trachea again. To minimize airway irritations during the process, we sprayed the airway with lidocaine before any manipulation. The neurophysiologists completed neuromoinitroing successfully and all three patients were satisfied with the anesthesia provided at follow-up.

CONCLUSION

Nasotracheal IEI and AAA anesthetic techniques should be considered as a viable option during DBS surgery.