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Awake craniotomy (AC) renders an expanded role in functional neurosurgery. Yet, evidence for optimal anaesthesia management remains limited. We aimed to summarise the latest clinical evidence of AC anaesthesia management and explore the relationship of AC failures on the used anaesthesia techniques. Two authors performed independently a systematic search of English articles in PubMed and EMBASE database 1/2007-12/2015. Search included randomised controlled trials (RCTs), observational trials, and case reports (n>4 cases), which reported anaesthetic approach for AC and at least one of our pre-specified outcomes: intraoperative seizures, hypoxia, arterial hypertension, nausea and vomiting, neurological dysfunction, conversion into general anaesthesia and failure of AC. Random effects meta-analysis was used to estimate event rates for four outcomes. Relationship with anaesthesia technique was explored using logistic meta-regression, calculating the odds ratios (OR) and 95% confidence intervals [95%CI]. We have included forty-seven studies. Eighteen reported asleep-awake-asleep technique (SAS), twenty-seven monitored anaesthesia care (MAC), one reported both and one used the awake-awake-awake technique (AAA). Proportions of AC failures, intraoperative seizures, new neurological dysfunction and conversion into general anaesthesia (GA) were 2% [95%CI:1-3], 8% [95%CI:6-11], 17% [95%CI:12-23] and 2% [95%CI:2-3], respectively. Meta-regression of SAS and MAC technique did not reveal any relevant differences between outcomes explained by the technique, except for conversion into GA. Estimated OR comparing SAS to MAC for AC failures was 0.98 [95%CI:0.36-2.69], 1.01 [95%CI:0.52-1.88] for seizures, 1.66 [95%CI:1.35-3.70] for new neurological dysfunction and 2.17 [95%CI:1.22-3.85] for conversion into GA. The latter result has to be interpreted cautiously. It is based on one retrospective high-risk of bias study and significance was abolished in a sensitivity analysis of only prospectively conducted studies. SAS and MAC techniques were feasible and safe, whereas data for AAA technique are limited. Large RCTs are required to prove superiority of one anaesthetic regime for AC.

Background Cerebral autoregulation (CA) can be impaired in patients with delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) . The Pressure Reactivity Index (PRx, correlation of blood pressure and intracranial pressure) and Oxygen Reactivity Index (ORx, correlation of cerebral perfusion pressure and brain tissue oxygenation, PbtO 2 ) are both believed to estimate CA. We hypothesized that CA could be poorer in hypoperfused territories during DCI and that ORx and PRx may not be equally effective in detecting such local variances. Methods ORx and PRx were compared daily in 76 patients with aSAH with or without DCI until the time of DCI diagnosis. The ICP/PbtO 2 -probes of DCI patients were retrospectively stratified by being in or outside areas of hypoperfusion via CT perfusion image, resulting in three groups: DCI + /probe + (DCI patients, probe located inside the hypoperfused area), DCI + /probe −  (probe outside the hypoperfused area), DCI −  (no DCI). Results PRx and ORx were not correlated ( r  =  −  0.01, p  = 0.56). Mean ORx but not PRx was highest when the probe was located in a hypoperfused area (ORx DCI + /probe + 0.28 ± 0.13 vs. DCI + /probe −  0.18 ± 0.15, p  < 0.05; PRx DCI + /probe + 0.12 ± 0.17 vs. DCI + /probe −  0.06 ± 0.20, p  = 0.35). PRx detected poorer autoregulation during the early phase with relatively higher ICP (days 1–3 after hemorrhage) but did not differentiate the three groups on the following days when ICP was lower on average. ORx was higher in the DCI + /probe + group than in the other two groups from day 3 onward. ORx and PRx did not differ between patients with DCI, whose probe was located elsewhere, and patients without DCI (ORx DCI + /probe −  0.18 ± 0.15 vs. DCI −  0.20 ± 0.14; p  = 0.50; PRx DCI + /probe −  0.06 ± 0.20 vs. DCI −  0.08 ± 0.17, p  = 0.35). Conclusions PRx and ORx are not interchangeable measures of autoregulation, as they likely measure different homeostatic mechanisms. PRx represents the classical cerebrovascular reactivity and might be better suited to detect disturbed autoregulation during phases with moderately elevated ICP. Autoregulation may be poorer in territories affected by DCI. These local perfusion disturbances leading up to DCI may be more readily detected by ORx than PRx. Further research should investigate their robustness to detect DCI and to serve as a basis for autoregulation-targeted treatment after aSAH.

Background In recent years, argon has been shown to exert neuroprotective effects in an array of models. However, the mechanisms by which argon exerts its neuroprotective characteristics remain unclear. Accumulating evidence imply that argon may exert neuroprotective effects via modulating the activation and polarization of microglia/macrophages after ischemic stroke. In the present study, we analyzed the underlying neuroprotective effects of delayed argon application until 7 days after reperfusion and explored the potential mechanisms. Methods Twenty-one male Wistar rats underwent transient middle cerebral artery occlusion or sham surgery randomly for 2 h using the endoluminal thread model. Three hours after transient middle cerebral artery occlusion induction and 1 h after reperfusion, animals received either 50% vol Argon/50% vol O 2 or 50% vol N 2 /50% vol O 2 for 1 h. The primary outcome was the 6-point neuroscore from 24 h to d7 after reperfusion. Histological analyses including infarct volume, survival of neurons (NeuN) at the ischemic boundary zone, white matter integrity (Luxol Fast Blue), microglia/macrophage activation (Iba1), and polarization (Iba1/Arginase1 double staining) on d7 were conducted as well. Sample size calculation was performed using nQuery Advisor + nTerim 4.0. Independent t test, one-way ANOVA and repeated measures ANOVA were performed, respectively, for statistical analysis (SPSS 23.0). Results The 6-point neuroscore from 24 h to d7 after reperfusion showed that tMCAO Ar group displayed significantly improved neurological performance compared to tMCAO N 2 group ( p  = 0.026). The relative numbers of NeuN-positive cells in the ROIs of tMCAO Ar group significantly increased compared to tMCAO N 2 group ( p  = 0.010 for cortex and p  = 0.011 for subcortex). Argon significantly suppressed the microglia/macrophage activation as revealed by Iba1 staining ( p  = 0.0076) and promoted the M2 microglia/macrophage polarization as revealed by Iba1/Arginase 1 double staining ( p  = 0.000095). Conclusions Argon administration with a 3 h delay after stroke onset and 1 h after reperfusion significantly alleviated neurological deficit within the first week and preserved the neurons at the ischemic boundary zone 7 days after stroke. Moreover, argon reduced the excessive microglia/macrophage activation and promoted the switch of microglia/macrophage polarization towards the anti-inflammatory M2 phenotype. Studies making efforts to further elucidate the protective mechanisms and to benefit the translational application are of great value.

Background Delayed cerebral ischemia (DCI) is a major cause of morbidity after aneurysmal subarachnoid hemorrhage (SAH). Endovascular treatment (ET) has emerged as a rescue strategy, but its optimal timing, indication, and modality remain unclear. This study assessed international ET practices, focusing on treatment variability and clinical decision-making. Methods A 25-question survey was developed with input from specialists in interventional neuroradiology, neurosurgery, neurology, and neurocritical care. It was disseminated via professional societies to physicians involved in bedside decisions. Respondents reviewed clinical scenarios representing common DCI presentations, including proximal/distal vasospasm and conscious/unconscious patients. Descriptive analysis was performed. Results 179 respondents from 38 countries participated; 76.5% reported ET availability at their institution. The most common strategy was single or repeated intra-arterial spasmolysis (76.5%), followed by continuous intra-arterial vasodilator infusion (23.0%). In unconscious patients, 50% applied spasmolysis as first-line treatment. For refractory proximal vasospasm, a stepwise approach was preferred, starting with intra-arterial pharmacologic spasmolysis, then angioplasty. While angioplasty was widely used, 66.5% considered it riskier than spasmolysis. Conclusion This survey highlights marked variability in ET practices for DCI. Intra-arterial spasmolysis is the predominant strategy, with alternative approaches like continuous infusion and angioplasty also in use. These findings underscore the need for randomized trials to define optimal ET strategies and inform evidence-based protocols for DCI following SAH.

Purpose Superficial temporal artery to middle cerebral artery (STA-MCA) direct bypass surgery is the most common surgical procedure to treat moyamoya disease (MMD). Here, we aim to compare the performance of the 3D exoscope in bypass surgery with the gold standard operative microscope. Methods All direct STA-MCA bypass procedures performed at a single university hospital for MMD between 2015 and 2023 were considered for inclusion. Data were retrospectively collected from patient files and surgical video material. From 2020 onwards, bypass procedures were exclusively performed using a digital three-dimensional exoscope as visualization device. Results were compared with a microsurgical bypass control group (2015–2019). The primary endpoint was defined as total duration of surgery, duration of completing the vascular anastomosis (ischemia time), bypass patency, number of stiches to perform the anastomosis, added stiches after leakage testing of the anastomosis and the Glasgow outcome scale (GOS) at last follow-up as secondary outcome parameter. Results A total of 16 consecutive moyamoya patients underwent 21 STA-MCA bypass procedures. Thereof, six patients were operated using a microscope and ten patients using an exoscope (ORBEYE® n  = 1; AEOS® n  = 9). Total duration of surgery was comparable between devices (microscope: 313 min. ± 116 vs. exoscope: 279 min. ± 42;  p  = 0.647). Ischemia time also proved similar between groups (microscope: 43 min. ± 19 vs. exoscope: 41 min. ± 7;  p  = 0.701). No differences were noted in bypass patency rates. The number of stiches per anastomosis was similar between visualization devices (microscope: 17 ± 4 vs. exoscope: 17 ± 2;  p  = 0.887). In contrast, more additional stiches were needed in microscopic anastomoses after leakage testing the bypass ( p  = 0.035). Conclusion Taking into account the small sample size, end-to-side bypass surgery for moyamoya disease using a foot switch-operated 3D exoscope was not associated with more complications and led to comparable clinical and radiological results as microscopic bypass surgery.

Background Delayed cerebral ischemia (DCI) is one of the main determinants of clinical outcome after aneurysmal subarachnoid hemorrhage (SAH). The classical description of risk for DCI over time is currently based on the outdated concept of angiographic vasospasm. The goal of this study was to assess the temporal risk profile of DCI, defined by extended clinical and radiological criteria, as well as the impact the time point of DCI onset has on clinical outcome. Methods All patients with aneurysmal SAH referred to a single tertiary care center between 2010 and 2018 were considered for inclusion. This study was designed as a retrospective cohort analysis and data were extracted from existing patient files. In conscious patients, DCI was diagnosed clinically, and in unconscious patients, diagnosis was based on perfusion computed tomography imaging and multimodal neuromonitoring. Extended Glasgow Outcome Scale scores were assessed after 12 months and compared between patients with early (< day 7) and late (≥ day 7) DCI onset. Results The median delay from day of the hemorrhage (day 0) until detection of the first DCI event was 7.0 days, with an interquartile range of 5 days. The probability of DCI development over time demonstrated a bimodal distribution with a peak risk on day 5 (0.084; confidence interval 0.05.5–0.122) and a second peak on day 9 (0.077; confidence interval 0.045–0.120). A total of 27 patients (15.6%) suffered dominant hemispheric or severe bilateral DCI-related infarctions, resulting in the withdrawal of technical life support. Of those, the majority (20 patients, 22.2%) presented with early DCI onset (vs. late onset: 7 patients, 8.4%; p  = 0.013). Conclusions The risk profile of DCI over time mirrors the description of angiographic vasospasm; however, it comes with an added timely delay of 1 to 2 days. Early occurrence of DCI (before day 7) is associated with a higher infarct load and DCI-related mortality. Although the exact causal relationship remains to be determined, the time point of DCI onset may serve as an independent prognostic criterion in decision-making.

In a previous study from our group, argon has shown to significantly attenuate brain injury, reduce brain inflammation and enhance M 2 microglia/macrophage polarization until 7 days after ischemic stroke. However, the long-term effects of argon have not been reported thus far. In the present study, we analyzed the underlying neuroprotective effects and potential mechanisms of argon, up to 30 days after ischemic stroke. Argon administration with a 3 h delay after stroke onset and 1 h after reperfusion demonstrated long-term neuroprotective effect by preserving the neurons at the ischemic boundary zone 30 days after stroke. Furthermore, the excessive microglia/macrophage activation in rat brain was reduced by argon treatment 30 days after ischemic insult. However, long-lasting neurological improvement was not detectable. More sensorimotor functional measures, age- and disease-related models, as well as further histological and molecular biological analyses will be needed to extend the understanding of argon’s neuroprotective effects and mechanism of action after ischemic stroke.

Background/Objectives: Chronic subdural hematoma (cSDH) is an increasingly prevalent neurosurgical condition in the aging population. Burr hole craniotomy (BHC) with irrigation and postoperative drainage represents the evidence-based standard of care, yet recurrence rates remain substantial. Twist drill craniostomy (TDC), a minimally invasive bedside procedure performed under local anesthesia, offers theoretical advantages for frail patients but has been largely abandoned due to concerns regarding incomplete evacuation and recurrence. This study aimed to identify the predictors of a successful TDC outcome and to compare the recurrence rates between TDC and BHC. Methods: We performed a retrospective cohort study of consecutive patients undergoing surgical treatment for radiologically confirmed cSDH at RWTH Aachen University Hospital between 2015 and 2023. Hematoma morphology was classified using an extended CT-based architecture system and grouped into homogeneous, organized, sedimented, or subacute categories. The primary endpoint was recurrence requiring surgical reintervention. Multivariable logistic regression was used to identify independent predictors of recurrence among patients discharged after definitive TDC. Propensity score matching was performed to compare recurrence rates between TDC and BHC while adjusting for baseline demographic, clinical, and radiographic differences. Results: Among 178 patients initially treated with TDC, 56 (31.5%) were discharged without conversion to BHC. Late recurrence occurred in 26 of 56 patients (46.4%) treated definitively with TDC. In multivariable analysis, homogeneous hematoma architecture was the only independent predictor of recurrence (adjusted OR 4.48, 95% CI 1.10–22.07, p = 0.037). Propensity score matching yielded 48 well-balanced pairs of TDC and BHC patients. Recurrence rates remained significantly higher after TDC compared with BHC (42.6% vs. 17.0%, p = 0.012), as confirmed by conditional logistic regression (adjusted OR 3.20, 95% CI 1.17–8.73). Conclusions: Twist drill craniostomy may provide definitive treatment in carefully selected patients but is associated with substantially higher recurrence rates than burr hole craniotomy, particularly in homogeneous hematomas. Burr hole evacuation remains the preferred standard approach, while optimized drainage protocols and architecture-guided selection may define a limited role for TDC in high-risk patients.

Background/Objectives: The transradial approach is widely used for vascular access in many disciplines. Radial artery occlusion (RAO) is a frequent sequel, and hand/arm pain affects 7.8% of patients. We aimed to elucidate whether RAO or ulnar artery occlusion (UAO) causes impaired neural blood flow and, thus, if symptoms may be attributable to claudication or nerve damage. Methods: Forty healthy volunteers (73% female), with a mean age of 38 years and without clinical or sonographic signs of carpal tunnel syndrome, were included. All underwent a standardized ultrasound examination (Aplio i800 and i22LH8 linear transducer, Canon Medical Systems) of the forearm, investigating the median nerve and its intraneural blood flow as well as the vascular status of the limb. The radial and ulnar arteries were then sequentially compressed, while changes to intraneural blood flow were noted. Thereafter, the (reverse) Barbeau test and the (inverse) modified Allen Test (MAT) were performed. Results: Simulated RAO and UAO halted intraneural blood flow in 65% and 62.5% of individuals, respectively. A total of 32.5% of participants reported discomfort in the hand/arm. Absent flow during occlusion was found at a significantly higher rate in symptomatic individuals. MAT and inverse MAT were abnormal (>10 s) in 17.5% and 7.5% of patients. Barbeau and reverse Barbeau produced type D results in 15% and 20%, respectively. Conclusions: Both simulated RAO and UAO caused the cessation of intraneural blood flow of the median nerve in two-thirds of participants, and a large proportion reported symptoms. MAT and Barbeau tests did not seem to be useful in predicting impaired neural blood flow.