Preoperative Risk Assessment Before Elective Craniotomy: Are Aspirin, Arrhythmias, Deep Venous Thromboses, and Hyperglycemia Contraindications to Surgery?

OBJECTIVE: Perioperative risk assessment and stratification before craniotomy is necessary to identify and optimize modifiable risk factors. Due to the high costs of diagnostic testing and concerns for delaying surgery, some have questioned whether and when surgery delays are warranted and supported by the current body of literature. The objective of this scoping review was to evaluate the available evidence on the prognostic value of preoperative risk assessment before anesthesia for elective craniotomy. METHODS: In this scoping review, we reviewed 156 papers that assess preoperative risk assessment before elective craniotomy, of which 27 papers were included in the final analysis. RESULTS: There is little high-quality evidence to suggest significant risk reduction when 4 common preexisting abnormalities are present: preoperative chronic aspirin therapy, cardiac arrhythmias, deep vein thrombosis, or hyperglycemia. CONCLUSIONS: The risk of delaying craniotomy should ultimately be weighed against the perceived risks associated the patient's comorbid conditions and should be considered on an individualized basis.

Heat and Moisture Exchanger Occlusion Leading to Sudden Increased Airway Pressure: A Case Report Using ChatGPT as a Personal Writing Assistant.

Heat and moisture exchangers (HMEs) are commonly used during general anesthesia to provide appropriate humidification and warming of inspired gases. While they play a critical role in mechanical ventilation, they can also lead to acute difficult ventilation if not correctly monitored and drained. We present a case of a 56-year-old female patient who underwent lower extremity vascular bypass surgery under general anesthesia and experienced sudden increased airway pressures due to occlusion of the HME caused by excessive moisture accumulation. Proper monitoring and management of the airway circuit and HMEs can help prevent complications and ensure proper ventilation during surgery. When acute difficult ventilation is encountered during general anesthesia, a systematic approach should be taken to differentiate between patient and external factors. Other differential diagnoses for acute difficult ventilation include bronchospasm, aspiration, endotracheal tube misplacement, pulmonary embolism, and tension pneumothorax. HME occlusion should be considered as part of the differential diagnosis for intraoperative hypoxia. Proactive replacement of HMEs in long cases can prevent occlusion and ensure proper ventilation.

Impact of postoperative fatigue following minimally-invasive lumbar spine surgery.

BACKGROUND: Postoperative fatigue is a distressing symptom and can have a major impact on the patient's quality of life after surgery. We investigate the extent of postoperative fatigue following minimally invasive spine surgery under general anesthesia (GA), and its impact on patients' quality of life (QOL) and activities of daily living (ADLs). METHODS: We surveyed patients that underwent minimally-invasive lumbar spine surgery under GA within the previous year. A five-point Likert scale ("very much", "quite a bit", "somewhat", "a little bit", "not at all") was used to assess the extent of fatigue during the first postoperative month, its impact on QOL, and ADLs. RESULTS: The survey was completed by 100 patients, 61% were male, mean age 64.6 ± 12.5 years, 31% underwent MIS-TLIF, 69% lumbar laminectomy. During the first postoperative month 45% of patients referred significant fatigue ("very much" or "quite a bit"); for 31% of patients fatigue significantly impacted their QOL; significantly limited their ADLs in 43% of patients. MIS-TLIF was associated with higher rate of postoperative fatigue compared to laminectomy (61.3% versus 37.7%, p = 0.02). Patients 65 years old or older had higher rates of fatigue compared to younger patients (55.6% versus 32.6%, p = 0.02). We did not observe a significant difference in postoperative fatigue between male and female patients. CONCLUSIONS: Our study revealed a substantial incidence of postoperative fatigue in patients that underwent minimally-invasive lumbar spine surgery under GA, with a significant impact on QOL and ADLs. There is a need to research new strategies to reduce fatigue after spine surgery.

Spine Surgery Under Spinal vs General Anesthesia: Prospective Analysis of Quality of Life, Fatigue, and Cognition.

BACKGROUND: There has recently been increasing interest in the use of spinal anesthesia (SA) for spine surgery. The literature that compared spine surgery under SA vs general anesthesia (GA) focused on safety, perioperative outcomes, and costs. OBJECTIVE: To test if SA is associated with less postoperative fatigue, cognitive dysfunction, and better quality of life in patients undergoing lumbar spine surgery compared with GA. METHODS: We conducted a prospective nonrandomized study in patients undergoing elective lumbar spine surgery under SA or GA by a single surgeon. Fatigue was assessed with the fatigue visual analog scale scale (0-10) and Chalder Fatigue Scale, quality of life with Medical Outcomes Study 12-item Short Form (SF-12), and differences in cognition with Mini-Mental State Examination. Patients were baselined before surgery and assessed again 1 mo after surgery. RESULTS: Fifty patients completed the study, 25 underwent surgery under SA and 25 under GA. The groups were homogeneous for baseline clinical characteristics, with no differences in preoperative fatigue, quality of life, and cognition. At 1 mo after surgery, SA compared with GA had better fatigue scores: fatigue visual analog scale (2.9 ± 1.5 vs 5.9 ± 2.3 [P < .0001]) and Chalder Fatigue Scale (11.2 ± 3.1 vs 16.9 ± 3.9 [P < .0001]). One month postoperatively, we observed a significant difference in the SF-12 physical component, with SA having 38.8 ± 8.9 vs 29.4 ± 10.3 (P = .002). We did not observe significant postoperative differences in the SF-12 mental component or Mini-Mental State Examination. CONCLUSION: Our study demonstrates that SA offers unique patient-centered advantages to GA for elective spine surgery. One month after surgery, patients who received SA had less postoperative fatigue and better quality of life.

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.

Oral glutamine supplementation increases seizure severity in a rodent model of mesial temporal lobe epilepsy.

Background: Glutamine synthetase (GS) is the only enzyme known to synthesize significant amounts of glutamine in mammals, and loss of GS in the hippocampus has been implicated in the pathophysiology of medication refractory mesial temporal lobe epilepsy (MTLE). Moreover, loss-of-function mutations of the GS gene causes severe epileptic encephalopathy, and supplementation with glutamine has been shown to normalize EEG and possibly improve the outcome in these patients. Here we examined whether oral glutamine supplementation is an effective treatment for MTLE by assessing the frequency and severity of seizures after supplementation in a translationally relevant model of the disease.Methods: Male Sprague Dawley rats (380-400 g) were allowed to drink unlimited amounts of glutamine in water (3.6% w/v; n = 8) or pure water (n = 8) for several weeks. Ten days after the start of glutamine supplementation, GS was chronically inhibited in the hippocampus to induce MTLE. Continuous video-intracranial EEG was collected for 21 days to determine the frequency and severity of seizures.Results: While there was no change in seizure frequency between the groups, the proportion of convulsive seizures was significantly higher in glutamine treated animals during the first three days of GS inhibition.Conclusion: The results suggest that oral glutamine supplementation transiently increases seizure severity in the initial stages of an epilepsy model, indicating a potential role of the amino acid in seizure propagation and epileptogenesis.

Spinal versus general anesthesia for minimally invasive transforaminal lumbar interbody fusion: implications on operating room time, pain, and ambulation.

OBJECTIVE: There has been increasing interest in the use of spinal anesthesia (SA) for spine surgery, especially within Enhanced Recovery After Surgery (ERAS) protocols. Despite the wide adoption of SA by the orthopedic practices, it has not gained wide acceptance in lumbar spine surgery. Studies investigating SA versus general anesthesia (GA) in lumbar laminectomy and discectomy have found that SA reduces perioperative costs and leads to a reduction in analgesic use, as well as to shorter anesthesia and surgery time. The aim of this retrospective, case-control study was to compare the perioperative outcomes of patients who underwent minimally invasive surgery (MIS)-transforaminal lumbar interbody fusion (TLIF) after administration of SA with those who underwent MIS-TLIF under GA. METHODS: Overall, 40 consecutive patients who underwent MIS-TLIF by a single surgeon were analyzed; 20 patients received SA and 20 patients received GA. Procedure time, intraoperative adverse events, postoperative adverse events, postoperative length of stay, 3-hour postanesthesia care unit (PACU) numeric rating scale (NRS) pain score, opioid medication, and time to first ambulation were collected for each patient. RESULTS: The two groups were homogeneous for clinical characteristics. A decrease in total operating room (OR) time was found for patients who underwent MIS-TLIF after administration of SA, with a mean OR time of 156.5 ± 18.9 minutes versus 213.6 ± 47.4 minutes for patients who underwent MIS-TLIF under GA (p < 0.0001), a reduction of 27%. A decrease in total procedure time was also observed for SA versus GA (122 ± 16.7 minutes vs 175.2 ± 10 minutes; p < 0.0001). No significant differences were found in intraoperative and postoperative adverse events. There was a difference in the mean maximum NRS pain score during the first 3 hours in the PACU as patients who received SA reported a lower pain score compared with those who received GA (4.8 ± 3.5 vs 7.3 ± 2.7; p = 0.018). No significant difference was observed in morphine equivalents received by the two groups. A difference was also observed in the mean overall NRS pain score, with 2.4 ± 2.1 for the SA group versus 4.9 ± 2.3 for the GA group (p = 0.001). Patients who received SA had a shorter time to first ambulation compared with those who received GA (385.8 ± 353.8 minutes vs 855.9 ± 337.4 minutes; p < 0.0001). CONCLUSIONS: The results of this study have pointed to some important observations in this patient population. SA offers unique advantages in comparison with GA for performing MIS-TLIF, including reduced OR time and postoperative pain, and faster postoperative mobilization.

Perioperative Glycemia Management in Patients Undergoing Craniotomy for Brain Tumor Resection: A Global Survey of Neuroanesthesiologists' Perceptions and Practices.

OBJECTIVE: There is a paucity of clinical evidence that guides perioperative glycemia management in patients undergoing craniotomy for brain tumor resection. The purpose of this study was to better understand global perceptions and practices related to glycemia management in these patients. METHODS: Neuroanesthesiologists throughout North America, South America, Europe, and Asia filled out a brief online questionnaire related to their perceptions and practices regarding glycemia management in patients undergoing craniotomy for brain tumor resection. RESULTS: Over 4 weeks, 435 participants practicing in 34 countries across 6 continents participated in this survey. Although responders in North America were found to perceive a higher risk hyperglycemia compared with those practicing in European (P = 0.024) and South Asian (P = 0.007) countries, responders practicing in South Asian countries (P = 0.030), Middle Eastern countries (P = 0.029), and South American (P = 0.005) countries were more likely than those from North America to remeasure glucose after an initial normal glucose measurement at incision. Responders from North America reported that a higher blood glucose threshold was necessary for them to delay or cancel the surgery compared with responders in Slavic (P < 0.001), European (P = 0.002), South American (P = 0.002), and Asian and Pacific (P < 0.001) countries. Responders from North America were more likely to report that they would delay or cancel the surgery because of a higher blood glucose threshold. CONCLUSIONS: Our survey results suggest that perceptions and practices related to blood glucose management in patients undergoing brain tumor resection are variable. This study highlights the need for stronger clinical evidence and guidelines to help guide decisions for when and how to manage blood glucose derangements in these patients.

Increased branched-chain amino acids at baseline and hours before a spontaneous seizure in the human epileptic brain.

The objective of this study was to monitor the extracellular brain chemistry dynamics at baseline and in relation to spontaneous seizures in human patients with refractory epilepsy. Thirty patients with drug-resistant focal epilepsy underwent intracranial electroencephalography and concurrent brain microdialysis for up to 8 continuous days. Extracellular brain glutamate, glutamine, and the branched-chain amino acids (BCAAs) valine, leucine, and isoleucine were quantified in the dialysis samples by liquid chromatography-tandem mass spectrometry. Extracellular BCAAs and glutamate were chronically elevated at baseline by approximately 1.5-3-fold in brain regions of seizure onset and propagation versus regions not involved by seizures. Moreover, isoleucine increased significantly above baseline as early as 3 h before a spontaneous seizure. BCAAs play important roles in glutamatergic neurotransmission, mitochondrial function, neurodegeneration, and mammalian target of rapamycin signaling. Because all of these processes have been implicated in epilepsy, the results suggest a novel role of BCAAs in the pathogenesis of spontaneous seizures.

Intraoperative management of thrombectomy for acute ischemic stroke: Do we need general anesthesia?

Since 2015, endovascular thrombectomy has been established as the standard of care for re-establishing cerebral blood flow in patients with acute ischemic stroke. Several retrospective observational studies and prospective clinical trials have investigated two anesthetic techniques for endovascular stroke therapy: general anesthesia (GA) and conscious sedation (CS). The recent randomized studies suggest that GA is associated with higher rates of successful recanalization and better functional independence at 3 months compared with the CS technique. However, CS techniques are highly variable, and there is currently a lack of consensus on which anesthetic approach is best in all patients. Numerous patient and procedural factors should ultimately guide the decision of whether GA or CS should be used for a particular patient.

Astroglial Glutamine Synthetase and the Pathogenesis of Mesial Temporal Lobe Epilepsy.

The enzyme glutamine synthetase (GS), also referred to as glutamate ammonia ligase, is abundant in astrocytes and catalyzes the conversion of ammonia and glutamate to glutamine. Deficiency or dysfunction of astrocytic GS in discrete brain regions have been associated with several types of epilepsy, including medically-intractable mesial temporal lobe epilepsy (MTLE), neocortical epilepsies, and glioblastoma-associated epilepsy. Moreover, experimental inhibition or deletion of GS in the entorhinal-hippocampal territory of laboratory animals causes an MTLE-like syndrome characterized by spontaneous, recurrent hippocampal-onset seizures, loss of hippocampal neurons, and in some cases comorbid depressive-like features. The goal of this review is to summarize and discuss the possible roles of astroglial GS in the pathogenesis of epilepsy.

Network-Related Changes in Neurotransmitters and Seizure Propagation During Rodent Epileptogenesis.

OBJECTIVE: To test the hypothesis that glutamate and GABA are linked to the formation of epilepsy networks and the triggering of spontaneous seizures, we examined seizure initiation/propagation characteristics and neurotransmitter levels during epileptogenesis in a translationally relevant rodent model of mesial temporal lobe epilepsy. METHODS: The glutamine synthetase (GS) inhibitor methionine sulfoximine was infused into one of the hippocampi in laboratory rats to create a seizure focus. Long-term video-intracranial EEG recordings and brain microdialysis combined with mass spectrometry were used to examine seizure initiation, seizure propagation, and extracellular brain levels of glutamate and GABA. RESULTS: All seizures (n = 78 seizures, n = 3 rats) appeared first in the GS-inhibited hippocampus of all animals, followed by propagation to the contralateral hippocampus. Propagation time decreased significantly from 11.65 seconds early in epileptogenesis (weeks 1-2) to 6.82 seconds late in epileptogenesis (weeks 3-4, paired t test, p = 0.025). Baseline extracellular glutamate levels were 11.6-fold higher in the hippocampus of seizure propagation (7.3 µM) vs the hippocampus of seizure onset (0.63 µM, analysis of variance/Fisher least significant difference, p = 0.01), even though the concentrations of the major glutamate transporter proteins excitatory amino acid transporter subtypes 1 and 2 and xCT were unchanged between the brain regions. Finally, extracellular GABA in the seizure focus decreased significantly from baseline several hours before a spontaneous seizure (paired t test/false discovery rate). CONCLUSION: The changes in glutamate and GABA suggest novel and potentially important roles of the amino acids in epilepsy network formation and in the initiation and propagation of spontaneous seizures.

Absence seizures and their relationship to depression and anxiety: Evidence for bidirectionality.

Absence seizures (AS), presenting as short losses of consciousness with staring spells, are a common manifestation of childhood epilepsy that is associated with behavioral, emotional, and social impairments. It has also been suggested that patients with AS are more likely to suffer from mood disorders such as depression and anxiety. This systematic review and meta-analysis synthesizes human and animal models that investigated mood disorders and AS. Of the 1019 scientific publications identified, 35 articles met the inclusion criteria for this review. We found that patients with AS had greater odds of developing depression and anxiety when compared to controls (odds ratio = 4.93, 95% confidence interval = 2.91-8.35, p < .01). The included studies further suggest a strong correlation between AS and depression and anxiety in the form of a bidirectional relationship. The current literature emphasizes that these conditions likely share underlying mechanisms, such as genetic predisposition, neurophysiology, and anatomical pathways. Further research will clarify this relationship and ensure more effective treatment for AS and mood disorders.

Reduced Pain and Opioid Use in the Early Postoperative Period in Patients Undergoing a Frontotemporal Craniotomy under Regional vs General Anesthesia.

INTRODUCTION: This study compares the postsurgical course of frontotemporal craniotomies conducted "awake" under regional anesthesia (RA) versus "asleep" under general anesthesia (GA) to investigate postoperative recovery, pain, opioid use, and anesthesia-related side effects. METHODS: We retrospectively reviewed craniotomies for supratentorial, intra-axial tumors with frontotemporal exposure. Chronic opioid use and emergent cases were excluded. Primary outcomes included pain scores on a 0-10 numerical rating scale, opioid use as oral morphine milligram equivalence, first time to opioid use, nausea, and sedation on the Richmond Agitation and Sedation Scale (RASS). Secondary outcomes included postoperative seizures, Karnofsky Performance Scale (KPS) status, and hospital length of stay (LOS). RESULTS: A total of 91 patients met inclusion criteria: 56 underwent a craniotomy under RA versus 35 under GA. Demographics and operative characteristics were similar between cohorts. A significant reduction in both postoperative pain and opioid use was observed among RA versus GA (first postoperative pain score 2 vs. 5, P < 0.01; postoperative day [POD] 0 median pain score 2.5 vs. 4, P < 0.01; POD 0 mean opioid in mg 14.49 vs. 24.43, P < 0.01). The time until patients requested opioids for pain after surgery was prolonged for RA versus GA [mean 7.23 vs. 3.42 hours, P < 0.01). Somnolence (RASS < 0) on POD 0 was significantly reduced among RA versus GA, with 23% versus 43%. Both cohorts had equivocal postsurgical outcomes such as seizures, KPS, and hospital LOS. CONCLUSIONS: Frontotemporal craniotomy under RA during awake craniotomies provides better pain control, a reduction in opioid use, and less somnolence in the early postoperative period.

Airway Management in an Anatomically and Physiologically Difficult Airway.

A "difficult airway" should be suspected in patients with any anatomical or physiologic abnormality that might result in the loss of the airway or significant cardiopulmonary compromise upon induction of general anesthesia. Historically, an awake intubation has often been the preferred approach for airway management in these patients. Here we describe a case in which an awake intubation was safely performed in a patient with both anatomical (i.e., laryngeal mass) and physiologic (i.e., pulmonary hypertension) abnormalities. Oxygenation, airway patency, and spontaneous breathing were well maintained with successful intubation on the first attempt. We recommend that the patient's physiologic state should always be considered in airway management planning.

Induction of General Anesthesia and Mask Ventilation With a Full-Face Continuous Positive Airway Pressure Mask in a Patient With a Nose Deformity.

Mask ventilation (MV) is an essential component of airway management and can be lifesaving in situations where the placement of a secure airway device proves challenging. Effective MV requires a seal to be created between the mask and the face to maintain patency of the external airway structures and can be difficult in the setting of facial abnormalities or facial trauma. Here we describe a case in which a continuous positive airway pressure (CPAP) mask was used for anesthesia induction and MV in an 85-year-old man who underwent a plastic surgery reconstruction of the left nasal dorsum and ala following a Mohs surgery, which had prevented the use of conventional face mask. An effective seal was achieved, and anesthesia was successfully induced with the mask. We reviewed the literature and discussed alternative approaches for face mask use in the setting of facial abnormalities where the use of a conventional mask is unfeasible.

Circadian-Like Rhythmicity of Extracellular Brain Glutamate in Epilepsy.

Seizures often exhibit striking circadian-like (~24-h) rhythms. While chronotherapy has shown promise in treating epilepsy, it is not widely used, in part because the patterns of seizure rhythmicity vary considerably among patients and types of epilepsy. A better understanding of the mechanisms underlying rhythmicity in epilepsy could be expected to result in more effective approaches which can be tailored to each individual patient. The excitatory neurotransmitter glutamate is an essential modulator of circadian rhythms, and changes in the extracellular levels of glutamate likely affect the threshold to seizures. We used a reverse translational rodent model of mesial temporal lobe epilepsy (MTLE) combined with long-term intracerebral microdialysis to monitor the hourly concentrations of glutamate in the seizure onset area (epileptogenic hippocampus) over several days. We observed significant 24-h oscillations of extracellular glutamate in the epileptogenic hippocampus (n = 4, JTK_CYCLE test, p < 0.05), but not in the hippocampus of control animals (n = 4). To our knowledge, circadian glutamate oscillations have not been observed in a seizure onset region, and we speculate that the oscillations contribute to the rhythmicity of seizures in MTLE.

Branched-Chain Amino Acids and Seizures: A Systematic Review of the Literature.

BACKGROUND: Up to 40% of patients with epilepsy experience seizures despite treatment with antiepileptic drugs; however, branched-chain amino acid (BCAA) supplementation has shown promise in treating refractory epilepsy. OBJECTIVES: The purpose of this systematic review was to evaluate all published studies that investigated the effects of BCAAs on seizures, emphasizing therapeutic efficacy and possible underlying mechanisms. METHODS: On 31 January, 2017, the following databases were searched for relevant studies: MEDLINE (OvidSP), EMBASE (OvidSP), Scopus (Elsevier), the Cochrane Library, and the unindexed material in PubMed (National Library of Medicine/National Institutes of Health). The searches were repeated in all databases on 18 February, 2019. We only included full-length preclinical and clinical studies that were published in the English language that examined the effects of BCAA administration on seizures. RESULTS: Eleven of 2045 studies met our inclusion criteria: ten studies were conducted in animal models and one study in human subjects. Seven seizure models were investigated: the strychnine (one study), pentylenetetrazole (two studies), flurothyl (one study), picrotoxin (two studies), genetic absence epilepsy in rats (one study), kainic acid (two studies), and methionine sulfoximine (one study) paradigms. Three studies investigated the effect of a BCAA mixture whereas the other studies explored the effects of individual BCAAs on seizures. In most animal models and in humans, BCAAs had potent anti-seizure effects. However, in the methionine sulfoximine model, long-term BCAA supplementation worsened seizure propagation and caused neuron loss, and in the genetic absence epilepsy in rats model, BCAAs exhibited pro-seizure effects. CONCLUSIONS: The contradictory effects of BCAAs on seizure activity likely reflect differences in the complex mechanisms that underlie seizure disorders. Some of these mechanisms are likely mediated by BCAA's effects on glucose, glutamate, glutamine, and ammonia metabolism, activation of the mechanistic target of rapamycin signaling pathway, and their effects on aromatic amino acid transport and neurotransmitter synthesis. We propose that a better understanding of mechanisms by which BCAAs affect seizures and neuronal viability is needed to advance the field of BCAA supplementation in epilepsy.