Neuroanaesthesia: Journals & articles

Abstract
Intraoperative neuromonitoring has been a valuable tool for ensuring the functional integrity of vital neural structures by providing real-time feedback to the operative team during procedures where neurological structures are at risk. Commonly used intravenous and inhaled anesthetic drugs are known to affect waveform parameters measured with various intraoperative neuromonitoring modalities. While the concept of opioid-sparing multimodal analgesia has gained popularity in recent years, the impact of such a strategy on intraoperative neuromonitoring remains poorly characterized, in contrast to the more well-established concepts and literature regarding the effects of other hypnotic agents on neuromonitoring quality. The purpose of this focused review is to provide an overview of the clinical evidence pertaining to the pharmacological interaction of certain multimodal analgesics with routine intraoperative neuromonitoring modalities.

Abstract
Background: The optimal general anesthetic (GA) technique for stroke patients undergoing endovascular thrombectomy (ET) is unclear. We compared favorable outcomes and mortality in patients receiving propofol or volatile GA during ET and assessed associations between mean arterial pressure (MAP) and outcome.

Methods: Ninety-three patients with anterior circulation stroke who received propofol or volatile GA during ET between February 2015 and February 2018 were included in this retrospective study. Ninety-day modified Rankin scores were compared and mortality was adjusted for intravenous thrombolysis and diabetes. We performed ordinal logistic regression analyses containing MAP time/exposure thresholds.

Results: There was no difference in the rate of favorable outcome (modified Rankin scores 0-2) in the volatile and propofol groups (48.8% vs. 55.8%, respectively; P=0.5). Ninety-day mortality was lower in patients receiving propofol (11.5%) than in those receiving volatile GA (29.3%) (odds ratio, 0.32; 95% confidence interval, 0.11 to 0.94; P=0.03); this mortality benefit was greater in patients that did not receive intravenous thrombolysis before ET (odds ratio for survival, 6; 95% confidence interval, 1.13 to 31.74). There was no difference in MAP between groups and a (nonsignificant) trend towards the benefit of MAP <90 mm Hg but not <70 mm Hg.

Conclusions: Favorable outcome rates were similar in stroke patients receiving propofol or volatile GA during ET. Propofol was associated with lower mortality, an effect magnified in patients that did not receive intravenous thrombolysis. MAP time/exposure thresholds were associated with outcome but independent of the anesthetic agent. Our data suggest that a difference in outcome related to an anesthetic agent may exist; this hypothesis needs to be tested in a prospective study.

Abstract
Objectives: A systematic review of original research articles was conducted to evaluate the safety and efficacy of lidocaine infusion in the treatment of adult patients with chronic neuropathic pain.

Materials and methods: Original research from 1970 to September 2021 describing adult patients with chronic neuropathic pain receiving at least 1 dose of intravenous lidocaine was included. Extracted data included study design, sample size, patient demographics and comorbidities, etiology and duration of pain, pain intensity scores, time to pain resolution, lidocaine dose and administration frequency, lidocaine serum concentration, and adverse events. Each study was evaluated for level of evidence using the 2017 American Association of Neurology classification system.

Results: Twenty-seven studies evaluating lidocaine infusion treatment in chronic neuropathic pain met inclusion criteria. One class I study was identified for patients with neuropathic pain due to spinal cord injury . Two Class II studies were identified, one describing neuropathic pain due to peripheral nerve injury and another due to diabetic neuropathy. Across all studies, study design, participants, and experimental interventions were heterogenous with wide variation.

Discussion: This qualitative review found insufficient, heterogenous evidence and therefore no recommendation can be made for lidocaine infusion treatment in patients with chronic neuropathic pain due to spinal cord injury, peripheral nerve injury, diabetic neuropathy, postherpetic neuralgia, or complex regional pain syndrome type II. Larger randomized, double-blind, placebo-controlled studies are required to further establish the efficacy of lidocaine infusion in patients with these etiologies of chronic neuropathic pain.

Abstract
Background: Neuraxial blocks is the recommended mode of analgesia and anesthesia in parturients with Coronavirus 19 (COVID-19). There is limited data on the hemodynamic responses to neuraxial blocks in COVID-19 patients. We aim to compare the hemodynamic responses to neuraxial blocks in COVID-19 positive and propensity-matched COVID-19 negative parturients.

Methods: We conducted retrospective, cross-sectional case-control study of hemodynamic changes associated with neuraxial blocks in COVID-19 positive parturients in a Tertiary care academic medical center. Fifty-one COVID-19 positive women confirmed by nasopharyngeal reverse transcription-polymerase chain reaction (RT-PCR), were compared with propensity-matched COVID negative controls (n = 51). Hemodynamic changes after neuraxial block were recorded by electronic medical recording system and analyzed using paired and unpaired T- test and Wilcoxon-Mann-Whitney Rank Sum tests. The primary outcome was ≥ 20% change in MAP and HR after neuraxial block placement.

Results: In the epidural group, 7% COVID-19 positive parturients had > 20% decrease in mean arterial pressure (MAP) from baseline compared to 15% COVID-19 negative parturients (P = 0.66). In the spinal group, 83% of COVID-19 positive parturients had a decrease in MAP more than 20% from baseline compared to 71% in control (P = 0.49). MAP drop of more than 40% occurred in 29% COVID positive parturients in the spinal group versus 17% in COVID-19 negative parturients (P = 0.5465). In COVID-19 positive spinal group, 54% required vasopressors whereas 38% in COVID-19 negative spinal group required vasopressors (P = 0.387). We found a significant correlation between body mass index (BMI) > 30 and hypotension in COVID ( +) parturient with odds ratio (8.63; 95% CI-1.93 - 37.21) (P = 0.007).

Conclusion: Incidence and severity of hypotension after neuraxial blocks were similar between COVID-19 positive and COVID-19 negative parturients. BMI > 30 was a significant risk factor for hypotension as described in preexisting literature, this correlation was seen in COVID-19 positive parturients. The likely reason for parturients with BMI > 30 in COVID negative patients not showing similar correlation, is that the sample size was small.

Purpose: Brain death/death by neurologic criteria (BD/DNC) may be determined in many countries by a clinical examination that shows coma, brainstem areflexia, and apnea, provided the conditions causing reversible loss of brain function are excluded a priori. To date, accounts of recovery from BD/DNC in adults have been limited to noncompliance with guidelines.

Clinical features: We report the case of a 72-yr-old man with a combined primary infratentorial (hemorrhagic) and secondary global (anoxic) brain lesion in whom decompressive craniectomy of the posterior fossa and six-hour therapeutic hypothermia (33-34°C) followed by 8-hour rewarming to ≥ 36°C were conducted. Thirteen hours later, clinical findings of brain function loss were documented in addition to guideline-compliant exclusion of reversible causes (arterial hypotension, intoxication, depressant drug effects, relevant metabolic or endocrine disequilibrium, chronic hypercapnia, neuromuscular disorders, and administration of a muscle relaxant). Since a primary infratentorial brain lesion was present, German guidelines required further ancillary testing. Doppler ultrasonography revealed some preserved cerebral circulation, and BD/DNC was not diagnosed. Approximately 24 hr after rewarming to ≥ 36°C, the patient exhibited respiratory efforts. He continued with assisted respiration until final asystole/apnea, without regaining additional brain function other than mild signs of hemispasticity. Follow-up computed tomography showed partial herniation of the cerebellum through the craniectomy gap of the posterior fossa, alleviating caudal brain stem compression.

Conclusions: Therapeutic decompressive craniectomy of the posterior fossa may allow for delayed reversal of apnea. In these patients, proof of cerebral circulatory arrest should be mandatory for diagnosing BD/DNC.

Background: The pressure reactivity index (PRx) has emerged as a surrogate method for the continuous bedside estimation of cerebral autoregulation and a predictor of unfavorable outcome after traumatic brain injury (TBI). However, calculation of PRx require continuous high-resolution monitoring currently limited to specialized intensive care units. The aim of this study was to evaluate a new index, the ultra-low-frequency PRx (UL-PRx) sampled at ∼0.0033 Hz at ∼5 minutes periods, and to investigate its association with outcome.

Methods: Demographic data, admission Glasgow coma scale, in-hospital mortality and Glasgow outcome scale extended at 12 months were extracted from electronic records. The filtering and preparation of time series of intracranial pressure (ICP), mean arterial pressure and cerebral perfusion pressure (CPP), and calculation of the indices (UL-PRx, Δ-optimal CPP), were performed in MATLAB using an in-house algorithm.

Results: A total of 164 TBI patients were included in the study; in-hospital and 12-month mortality was 29.3% and 38.4%, respectively, and 64% of patients had poor neurological outcome at 12 months. On univariate analysis, ICP, CPP, UL-PRx, and ΔCPPopt were associated with 12-month mortality. After adjusting for age, Glasgow coma scale, ICP and CPP, mean UL-PRx and UL-PRx thresholds of 0 and +0.25 remained associated with 12-month mortality. Similar findings were obtained for in-hospital mortality. For mean UL-PRx, the area under the receiver operating characteristic curves for in-hospital and 12-month mortality were 0.78 (95% confidence interval [CI]: 0.69-0.87; P<0.001) and 0.70 (95% CI: 0.61-0.79; P<0.001), respectively, and 0.65 (95% CI: 0.57-0.74; P=0.001) for 12-month neurological outcome.

Conclusions: Our findings indicate that ultra-low-frequency sampling might provide sufficient resolution to derive information about the state of cerebrovascular autoregulation and prediction of 12-month outcome in TBI patients

Background: During the first wave of the coronavirus disease-2019 (COVID-19) pandemic, it was necessary to prepare for the possibility of triaging patients who could benefit from access to an intensive care unit (ICU). In our neuroscience institution, the challenge was to continue to manage usual neurological emergencies as well as the influx of COVID-19 patients.

Methods: We report the experience of an ethical consulting unit to support care clinical decisions during the first wave of the pandemic (March 16 to April 30, 2020). Three objective evaluation criteria were defined: 2 of these criteria, patient's factors and general disease severity (Simplified Acute Physiology Score II), were common to all patients, and the third was the specific severity of the disease (neurological for brain injury, respiratory for COVID-19). Given our scarce resources, we used a high probability of a 3-month modified Rankin Scale ≤3 as the criterion for further resuscitation and management.

Results: A total of 295 patients were admitted during the first pandemic wave; 111 with COVID-19 and 184 with neurological emergencies. The ethical unit's expertise was sought for 75 clinical situations in 56 patients (35 COVID-19 and 21 neurological). Decisions were as follows: 11% no limitation on care, 5% expectant care with reassessment (maximum therapy to assess possible progress pending decision), 67% partial limitation (no intensification of care or no transfer to ICU), and 17% limitation of curative care. At no time did a lack of availability of ICU beds require the ethical unit to advise against admission to the ICU.

Conclusions: Our ethical consulting unit allowed for collegial ethical decision-making in line with international recommendations. This model could be easily transferred to other triage situations, provided it is adapted to the local context.

Introduction: The purpose of this study was to examine the association with in-hospital mortality of 8 illness severity scores in patients with aneurysmal subarachnoid hemorrhage (aSAH).

Methods: In a retrospective cohort study, we investigated the association with in-hospital mortality of admission Hunt and Hess (HH) score, Fisher grade, severity of illness and risk of mortality scores, and serial Glasgow coma scale (GCS) score in patients with aSAH. We also explored the changes in GCS between admission and discharge using a multivariate model adjusting for age, clinical vasospasm, and external ventricular drain status.

Results: Data from 480 patients with aSAH, of which 383 (79.8%) aneurysms were in the anterior circulation, were included in analysis. Patients were female (n=340, 70.8%) with a median age of 56 (interquartile range: 48 to 66) years. The majority (n=332, 69.2%) had admission HH score 3 to 5, Fisher grade 3 to 4 (n=437, 91%), median severity of illness 3 (range: 1 to 4), median risk of mortality 3 (range: 1 to 4), and median admission GCS of 13 (interquartile range: 7 to 15). Overall, 406 (84.6%) patients received an external ventricular drain, 469 (97.7%) underwent aneurysm repair, and 60 died (12.5%). Compared with admission HH score, GCS 24 hours after admission (area under the curve: 0.84, 95% confidence interval [CI]: 0.79-0.88) and 24 hours after aneurysm repair (area under the curve: 0.87, 95% CI: 0.82-0.90) were more likely to be associated with in-hospital mortality. Among those who died, the greatest decline in GCS was noted between 24 hours after aneurysm repair and discharge (-3.38 points, 95% CI: -4.17, -2.58).

Conclusions: Compared with admission HH score, GCS 24 hours after admission (or 24 h after aneurysm repair) is more likely to be associated with in-hospital mortality after aSAH.

Adequate analgesia is known to improve outcomes after spine surgery. Despite recent attention highlighting the negative effects of narcotics and their addiction potential, opioids have been the mainstay of management for providing analgesia following spine surgeries. However, side effects including hyperalgesia, tolerance, and subsequent dependence restrict the generous usage of opioids. Multimodal analgesia regimens acting through different mechanisms offer significant opioid sparing and minimize the side effects of individual drugs. Hence, they are being increasingly incorporated into enhanced recovery protocols. Multimodal analgesia includes drugs such as N-methyl-D-aspartate antagonists, nonsteroidal anti-inflammatory drugs and membrane-stabilizing agents, neuraxial opioids, local anesthetic infiltration, and fascial compartment blocks. Analgesia started before the painful stimulus, termed preemptive analgesia, facilitates subsequent pain management. Both nonsteroidal anti-inflammatory drugs and neuraxial analgesia have been conclusively shown to reduce opioid requirements after spine surgery, and there is a resurgence of interest in the use of low-dose ketamine or methadone. Neuraxial narcotics offer enhanced analgesia for a longer duration with lower dosage and side effect profiles compared with systemic opioid administration. Fascial compartment blocks are increasingly used as they provide effective analgesia with fewer adverse effects. In this narrative review, we will discuss multimodality analgesic regimens incorporating opioid-sparing adjuvants to manage pain after spine surgery.

One of the most common and distressing symptoms after craniotomy is postoperative nausea and vomiting (PONV). PONV could generate delayed postanesthesia care and hospitalization discharge, lower patient satisfaction, and an increase in overall hospitalization costs. The incidence of reported PONV after craniotomy is 22% to 70% without prophylaxis, and a multimodal regimen of medication has been recommended. We conducted a comprehensive literature review of the clinical evidence related to PONV prevention and management after craniotomy. All clinical trials in adult populations relevant to PONV after craniotomy available in English language and indexed in PubMed, Google Scholar and Cochrane Library databases from January 1997 up to September 2018 were retrieved using a combination of free-text words related to PONV in craniotomy. After screening manuscripts identified in the initial search, 23 clinical trials investigating systemic pharmacological intervention versus placebo or active control in patients undergoing craniotomy under general anesthesia met the criteria for inclusion in this comprehensive narrative review. The pathophysiology and mechanisms of PONV after craniotomy could be multifactorial in etiology. Therefore, based on current evidence, PONV management after craniotomy should focus on perioperative patient assessment, surgical, and anesthesia-related risk factors and the selection of systemic pharmacological considerations to reduce its incidence and complications. A multimodal regimen of medication targeting different chemoreceptors in the vomiting center is recommended. Ondansetron and dexamethasone, or their combination, are the most frequently used and effective agents. Further randomized clinical trials comparing different regimens that significantly reduce the incidence of PONV in craniotomy would provide relevant evidence-based data for PONV management in this patient population.

Abstract
Background: The association between cerebral desaturation and postoperative delirium in thoracotomy with one-lung ventilation (OLV) has not been specifically studied.

Methods: A prospective observational study performed in thoracic surgical patients. Cerebral tissue oxygen saturation (Scto2) was monitored on the left and right foreheads using a near-infrared spectroscopy oximeter. Baseline Scto2 was measured with patients awake and breathing room air. The minimum Scto2 was the lowest measurement at any time during surgery. Cerebral desaturation and hypersaturation were an episode of Scto2 below and above a given threshold for ≥15 seconds during surgery, respectively. The thresholds based on relative changes by referring to the baseline measurement were <80%, <85%, <90%, <95%, and <100% baseline for desaturation and >105%, >110%, >115%, and >120% baseline for hypersaturation. The thresholds based on absolute values were <50%, <55%, <60%, <65%, and <70% for desaturation and >75%, >80%, >85%, and >90% for hypersaturation. The given area under the threshold (AUT)/area above the threshold (AAT) was analyzed. Delirium was assessed until postoperative day 5. The primary analysis was the association between the minimum Scto2 and delirium using multivariable logistic regression controlled for confounders (age, OLV time, use of midazolam, occurrence of hypotension, and severity of pain). The secondary analysis was the association between cerebral desaturation/hypersaturation and delirium, and between the AUT/AAT and delirium using multivariable logistic regression controlled for the same confounders. Multiple testing was corrected using the Holm-Bonferroni method. We additionally monitored somatic tissue oxygen saturation on the forearm and upper thigh.

Results: Delirium occurred in 35 (20%) of 175 patients (65 ± 6 years old). The minimum left or right Scto2 was not associated with delirium. Cerebral desaturation defined by <90% baseline for left Scto2 (odds ratio [OR], 5.82; 95% confidence interval [CI], 2.12-19.2; corrected P =.008) and <85% baseline for right Scto2 (OR, 4.27; 95% CI, 1.77-11.0; corrected P =.01) was associated with an increased risk of delirium. Cerebral desaturation defined by other thresholds, cerebral hypersaturation, the AUT/AAT, and somatic desaturation and hypersaturation were all not associated with delirium.

Conclusions: Cerebral desaturation defined by <90% baseline for left Scto2 and <85% baseline for right Scto2, but not the minimum Scto2, may be associated with an increased risk of postthoracotomy delirium. The validity of these thresholds needs to be tested by randomized controlled trials.

Abstract
Anesthesiologists provide care to acute and subacute ischemic stroke (IS) patients and stroke survivors in interventional radiology, intensive care, and operating rooms. These encounters will become more frequent following studies that have extended the treatment window from last known well time for fibrinolytic and endovascular thrombectomy (EVT). The number of stroke centers certified to quickly and effectively initiate treatment of IS patients and the number of patients connected to them by telehealth continue to grow. This article reviews IS pathophysiology, assessment, treatment, pathology, and complications; anesthetic management during EVT; perioperative stroke management; and how anesthesia has an impact on patients with prior stroke.

Abstract
Background: The COVID-19 pandemic is an international crisis placing tremendous strain on medical systems around the world. Like other specialties, neuroanesthesiology has been adversely affected and training programs have had to quickly adapt to the constantly changing environment.

Methods: An email-based survey was used to evaluate the effects of the pandemic on clinical workflow, clinical training, education, and trainee well-being. The impact of the International Council on Perioperative Neuroscience Training (ICPNT) accreditation was also assessed.

Results: Responses were received from 14 program directors (88% response rate) in 10 countries and from 36 fellows in these programs. Clinical training was adversely affected because of the cancellation of elective neurosurgery and other changes in case workflow, the introduction of modified airway and other protocols, and redeployment of trainees to other sites. To address educational demands, most programs utilized online platforms to organize clinical discussions, journal clubs, and provide safety training modules. Several initiatives were introduced to support trainee well-being during the pandemic. Feelings of isolation and despair among trainees varied from 2 to 8 (on a scale of 1 to 10). Fellows all reported concerns that their clinical training had been adversely affected by the coronavirus disease 2019 (COVID-19) pandemic because of decreased exposure to elective subspecialty cases and limited opportunities to complete workplace-based assessments and training portfolio requirements. Cancellation of examination preparation courses and delayed examinations were cited as common sources of stress. Programs accredited by the ICPNT reported that international networking and collaboration was beneficial to reduce feelings of isolation during the pandemic.

Conclusion: Neuroanesthesia fellowship training program directors introduced innovative ways to maintain clinical training, educational activity and trainee well-being during the COVID-19 pandemic.

Frameless stereotactic biopsy is commonly employed for precision neurosurgery to increase diagnostic yield and patient safety. This technique avoids patient discomfort and allows for better airway management. Most patients receive general anaesthesia and perioperative complications are rare. There are no previous reports on anaesthetic management in a patient with Cheyne–Stokes respiration (CSR) and hence this report.

Published bimonthly and offering a unique and wide ranging perspective on the key developments in the field, each issue of Current Opinion in Anesthesiology features hand-picked review articles from our team of expert editors. With fifteen disciplines published across the year – including cardiovascular anaesthesiology, neuroanaesthesia and pain medicine – every issue also contains annotated references detailing the merits of the most important papers.

The Journal of Neurosurgical Anesthesiology (JNA) is a peer-reviewed journal which publishes articles on all aspects of perioperative neuroscience. Specifically, the journal's scope includes clinical neuroanaesthesiology and neurocritical care, foundational neuroscience of anaesthesiology and brain and spinal cord injury, and neurologic outcomes after non-neurologic surgery and critical illness. The journal publishes original clinical and laboratory investigations, review articles, research letters and other correspondence, and special articles including clinical practice guidelines.

Neuromodulation: Technology at the Neural Interface is the preeminent journal in the area of neuromodulation, providing our readership with the state of the art clinical, translational and basic science research in our field and representing the needs of the broad neuromodulation community. For clinicians, engineers, scientists and members of the biotechnology industry alike, Neuromodulation provides timely and rigorously peer reviewed articles on the technology, science and clinical application of devices that interface with the nervous system to treat disease and improve function. Neuromodulation covers an ever expanding field including pain, headache, movement disorders, spasticity, paralysis, psychiatric disorders, epilepsy, sensory deprivation, gastric dysfunction, obesity and incontinence.

World Neurosurgery: X offers authors with high-quality research who want to publish in a gold open access journal the opportunity to make their work immediately, permanently, and freely accessible.