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1.
  • Ekmark-Lewén, Sara, et al. (author)
  • Diffuse traumatic axonal injury in mice induces complex behavioural alterations that are normalized by neutralization of interleukin-1β
  • 2016
  • In: European Journal of Neuroscience. - : Wiley. - 0953-816X .- 1460-9568. ; 43:8, s. 1016-1033
  • Journal article (peer-reviewed)abstract
    • Widespread traumatic axonal injury (TAI) results in brain network dysfunction, which commonly leads to persisting cognitive and behavioural impairments following traumatic brain injury (TBI). TBI induces a complex neuroinflammatory response, frequently located at sites of axonal pathology. The role of the pro-inflammatory cytokine interleukin (IL)-1 has not been established in TAI. An IL-1-neutralizing or a control antibody was administered intraperitoneally at 30min following central fluid percussion injury (cFPI), a mouse model of widespread TAI. Mice subjected to moderate cFPI (n=41) were compared with sham-injured controls (n=20) and untreated, naive mice (n=9). The anti-IL-1 antibody reached the target brain regions in adequate therapeutic concentrations (up to similar to 30g/brain tissue) at 24h post-injury in both cFPI (n=5) and sham-injured (n=3) mice, with lower concentrations at 72h post-injury (up to similar to 18g/g brain tissue in three cFPI mice). Functional outcome was analysed with the multivariate concentric square field (MCSF) test at 2 and 9days post-injury, and the Morris water maze (MWM) at 14-21days post-injury. Following TAI, the IL-1-neutralizing antibody resulted in an improved behavioural outcome, including normalized behavioural profiles in the MCSF test. The performance in the MWM probe (memory) trial was improved, although not in the learning trials. The IL-1-neutralizing treatment did not influence cerebral ventricle size or the number of microglia/macrophages. These findings support the hypothesis that IL-1 is an important contributor to the processes causing complex cognitive and behavioural disturbances following TAI.
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3.
  • Björk, Sofie, et al. (author)
  • Thiopental and decompressive craniectomy as last-tier ICP-treatments in aneurysmal subarachnoid hemorrhage : is functional recovery within reach?
  • 2023
  • In: Neurosurgical review. - : Springer Nature. - 0344-5607 .- 1437-2320. ; 46:1
  • Journal article (peer-reviewed)abstract
    • The study aimed to investigate the indication and functional outcome after barbiturates and decompressive craniectomy (DC) as last-tier treatments for elevated intracranial pressure (ICP) in aneurysmal subarachnoid hemorrhage ( aSAH). This observational study included 891 aSAH patients treated at a single center between 2008 and 2018. Data on demography, admission status, radiology, ICP, clinical course, and outcome 1-year post-ictus were collected. Patients treated with thiopental ( barbiturate) and DC were the main target group. Thirty-nine patients (4%) were treated with thiopental alone and 52 (6%) with DC. These patients were younger and had a worse neurological status than those who did not require these treatments. Before thiopental, the median midline shift was 0 mm, whereas basal cisterns were compressed/obliterated in 66%. The median percentage of monitoring time with ICP > 20 mmHg immediately before treatment was 38%, which did not improve after 6 h of infusion. Before DC, the median midline shift was 10 mm, and the median percentage of monitoring time with ICP > 20 mmHg before DC was 56%, which both significantly improved postoperatively. At follow-up, 52% of the patients not given thiopental or operated with DC reached favorable outcome, whereas this occurred in 10% of the thiopental and DC patients. In summary, 10% of the aSAH cohort required thiopental, DC, or both. Thiopental and DC are important integrated last-tier treatment options, but careful patient selection is needed due to the risk of saving many patients into a state of suffering.
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4.
  • Blomquist, Erik, et al. (author)
  • Positive correlation between occlusion rate and nidus size of proton beam treated brain arteriovenous malformations (AVMs)
  • 2016
  • In: Acta Oncologica. - 0284-186X .- 1651-226X. ; 55:1, s. 105-112
  • Journal article (peer-reviewed)abstract
    • BACKGROUND: Proton beam radiotherapy of arteriovenous malformations (AVM) in the brain has been performed in Uppsala since 1991. An earlier study based on the first 26 patients concluded that proton beam can be used for treating large and medium sized AVMs that were considered difficult to treat with photons due to the risk of side effects. In the present study we analyzed the result from treating the subsequent 65 patients.MATERIAL AND METHODS: A retrospective review of the patients' medical records, treatment protocols and radiological results was done. Information about gender, age, presenting symptoms, clinical course, the size of AVM nidus and rate of occlusion was collected. Outcome parameters were the occlusion of the AVM, clinical outcome and side effects.RESULTS: The rate of total occlusion was overall 68%. For target volume 0-2cm(3) it was 77%, for 3-10 cm(3) 80%, for 11-15 cm(3) 50% and for 16-51 cm(3) 20%. Those with total regress of the AVM had significantly smaller target volumes (p < 0.009) higher fraction dose (p < 0.001) as well as total dose (p < 0.004) compared to the rest. The target volume was an independent predictor of total occlusion (p = 0.03). There was no difference between those with and without total occlusion regarding mean age, gender distribution or symptoms at diagnosis. Forty-one patients developed a mild radiation-induced brain edema and this was more common in those that had total occlusion of the AVM. Two patients had brain hemorrhages after treatment. One of these had no effect and the other only partial occlusion from proton beams. Two thirds of those presenting with seizures reported an improved seizure situation after treatment.CONCLUSION: Our observations agree with earlier results and show that proton beam irradiation is a treatment alternative for brain AVMs since it has a high occlusion rate even in larger AVMs.
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5.
  • Ekmark Lewén, Sara, 1978- (author)
  • Cellular Reactions and Behavioral Changes in Focal and Diffuse Traumatic Brain Injury : A Study in the Rat and Mouse
  • 2013
  • Doctoral thesis (other academic/artistic)abstract
    • Traumatic brain injury (TBI) is a severe condition and a major cause of death and disability. There is no pharmacological treatment available in clinical practice today and knowledge of brain injury mechanisms is of importance for development of neuroprotective drugs. The aims of the thesis were to get a better understanding of astrocyte reactions and immune responses, as well as behavioral changes after focal unilateral cortical contusion injury and diffuse bilateral central fluid percussion injury in rats and mice.In the focal injury models, the astrocyte reactions were generally restricted to the ipsilateral hemisphere. After diffuse TBI, vimentin and glial fibrillary acidic protein (GFAP) positive reactive astrocytes were bilaterally expressed in brain regions even distant from the injury site, including regions where axonal injury was seen. Early after diffuse TBI, there was a robust immune response, including activation of macrophages/microglia (Mac-2+) and infiltration of neutrophils (GR-1+) and T-cells (CD3+).In order to measure functional outcome, the recently established Multivariate Concentric Square Field™ (MCSF) test for complex behaviors, including risk taking and explorative strategies was used. The Morris water maze (MWM) was applied for testing learning and memory. The MCSF test revealed alterations in risk taking, risk assessment and exploratory behavior, in the mice subjected to focal injury whereas mice subjected to the diffuse injury showed a deviant stereotyped behavior. After focal injury mice showed a decreased ability to adapt to the arena in the second trial, when tested repeatedly in the MCSF test. Mice subjected to diffuse injury had an impaired memory but not learning, in the MWM test. Post-injury treatment with the anti-inflammatory anti-interleukin-1β (IgG2 a/k) antibody showed a positive effect on functional outcome in the diffuse injury model. Altogether, the results demonstrate that focal and diffuse TBI models produce differences in cellular reactions and behavioral outcome and that the immune response plays a key role in the pathology after brain injury. 
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6.
  • Ekmark-Lewén, Sara, et al. (author)
  • The Multivariate Concentric Square Field Test Reveals Behavioral Profiles of Risk Taking, Exploration, and Cognitive Impairment in Mice Subjected to Traumatic Brain Injury
  • 2010
  • In: Journal of Neurotrauma. - : Mary Ann Liebert Inc. - 0897-7151 .- 1557-9042. ; 27:9, s. 1643-1655
  • Journal article (peer-reviewed)abstract
    • There is a need for more efficient tests to evaluate functional outcome following experimental traumatic brain injury (TBI), reflecting deficits in cognitive, sensory, and motor functions that are seen in TBI patients. The Multivariate Concentric Square Field (TM) (MCSF) test is a relatively new behavioral model that measures exploration, risk taking, risk assessment, and shelter seeking, all of which are evolutionarily-conserved strategies for survival. The multivariate design enables scoring of different functional domains in a single test situation, with a free choice of optional environmental settings. Furthermore, repeated trials permits cognitive effects to be measured. In the present study, 11 anesthetized C57BL6 mice received controlled cortical injury (CCI) (0.5mm and 3.3 m/sec) over the right parietal cerebral cortex or sham surgery (n - 12). Naive mice (n 12) not subjected to any surgical procedure were also included. The animals were evaluated in the MCSF test at 2 and 7 days post-surgery, and behavioral profiles were analyzed. The results revealed differences in risk taking and explorative behavior between the sham animals and the animals subjected to trauma. Animals subjected to trauma were characterized by taking more risks and had a higher level of exploration activity, but they sought less shelter. Repeated exposure to the MCSF caused a general decrease in activity in the naive and sham group, while a more specific behavioral impairment was seen in injured mice, suggesting cognitive dysfunction. We submit that the MCSF test is a useful complementary tool for functional outcome evaluation in experimental TBI.
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7.
  • Ekmark-Lewén, Sara, et al. (author)
  • Traumatic axonal injury in the mouse is accompanied by a dynamic inflammatory response, astroglial reactivity and complex behavioral changes
  • 2013
  • In: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 10:1, s. 44-
  • Journal article (peer-reviewed)abstract
    • BackgroundDiffuse traumatic axonal injury (TAI), a common consequence of traumatic brain injury, is associated with high morbidity and mortality. Inflammatory processes may play an important role in the pathophysiology of TAI. In the murine central fluid percussion injury (cFPI) TAI model, the neuroinflammatory and astroglial response and behavioral changes are unknown.MethodsTwenty cFPI-injured and nine sham-injured mice were used, and the neuroinflammatory and astroglial response was evaluated by immunohistochemistry at 1, 3 and 7 days post-injury. The multivariate concentric square field test (MCSF) was used to compare complex behavioral changes in mice subjected to cFPI (n = 16) or sham injury (n = 10). Data was analyzed using non-parametric statistics and principal component analysis (MCSF data).ResultsAt all post-injury time points, beta-amyloid precursor protein (beta-APP) immunoreactivity revealed widespread bilateral axonal injury and IgG immunostaining showed increased blood--brain barrier permeability. Using vimentin and glial fibrillary acidic protein (GFAP) immunohistochemistry, glial cell reactivity was observed in cortical regions and important white matter tracts peaking at three days post-injury. Only vimentin was increased post-injury in the internal capsule and only GFAP in the thalamus. Compared to sham-injured controls, an increased number of activated microglia (MAC-2), infiltrating neutrophils (GR-1) and T-cells (CD3) appearing one day after TAI (P<0.05 for all cell types) was observed in subcortical white matter. In the MCSF, the behavioral patterns including general activity and exploratory behavior differed between cFPI mice and sham-injured controls.ConclusionsTraumatic axonal injury in mice resulted in marked bilateral astroglial and neuroinflammatory responses and complex behavioral changes. The cFPI model in mice appears suitable for the study of injury mechanisms, including neuroinflammation, and the development of treatments targeting traumatic axonal injury.
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8.
  • Ekmark-Lewén, Sara, et al. (author)
  • Vimentin and GFAP responses in astrocytes after contusion trauma to the murine brain
  • 2010
  • In: Restorative Neurology and Neuroscience. - 0922-6028 .- 1878-3627. ; 28:3, s. 311-321
  • Journal article (peer-reviewed)abstract
    • Purpose: Astroglial responses after traumatic brain injury are difficult to detect with routine morphological methods. The aims for this study were to compare the temporal and spatial expression pattern of vimentin-and glial fibrillary acidic protein (GFAP) in a weight drop model of mild cerebral contusion injury in the rat. We also wanted to study the vimentin response with immunohistochemistry and vimentin mRNA RT-PCR analysis in severe cortical contusion injury produced by the controlled cortical impact in the mouse. Methods: Vimentin and GFAP immunohistochemistry (1day, 3 days and 7 days) combined with vimentin mRNA RT-PCR analysis (1 h, 4 h, 22 h, 3 days and 7 days) were used after experimental traumatic brain injury in the rat and mouse. Results: Increases in post-traumatic vimentin mRNA levels in the cortex and in the hippocampus appeared together with vimentin immunoreactivity in astrocytes in the perimeter of the cortical lesion, in the subcortical white matter and in the hippocampus starting at one day after severe trauma. GFAP immunostaining revealed hypertrophic astrocytes peaking at day 3 in the perifocal cortical region. There was no significant increase in GFAP immunoreactivity in the white matter in the rat. However, in the mouse there was a slight increase in the number of GFAP positive cells in this region, 3 days after trauma. Overall the pattern of vimentin immunoreactivity was very similar in the rat and mouse. Conclusions: Vimentin immunoreactivity was more sensitive than the GFAP staining method to demonstrate the distribution and time course of astrocyte reactions after a contusion injury, especially in the white matter distant from the cortical lesion.
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9.
  • Galos, Peter, et al. (author)
  • Machine learning based prediction of imminent ICP insults during neurocritical care of traumatic brain injury
  • Other publication (other academic/artistic)abstract
    • Background/ObjectiveIncreased intracranial pressure (ICP) is a feared secondary brain insult in neurointensive care (NIC) of traumatic brain injury (TBI). A system that predicts ICP insults before they emerge may facilitate early optimization of the physiology, which in turn may lead to that the predicted ICP insult will never occur. The aim of this study was to evaluate the performance of different AI models in predicting risk of ICP insults. MethodsThe models were trained to predict risk of ICP insults starting within 30 minutes, using the Uppsala High Frequency TBI (UHF-TBI) dataset. A restricted dataset consisting of monitoring data only was used, and an unrestricted dataset using monitoring data as well as clinical data, demographic data and radiological evaluations. Four different model classes were compared: Gaussian Process Regression (GP), Logistic Regression (LR), Random Forest classifier (RF) and Extreme Gradient Boosted Decision Trees (XGBoost).ResultsSix hundred and two TBI patients were included (total monitoring 138 411 hours). On the task of predicting upcoming ICP insults, the GP model performed similar on the UHF-TBI dataset (sensitivity 93.2% and specificity 93.9%), as in earlier smaller studies. Using a more flexible model (XGBoost) resulted in slightly better performance (sensitivity 93.8% and specificity 94.6%). Adding more clinical variables and features further improved the performance of the models slightly (XGBoost: sensitivity 94.1% and specificity of 94.6%). Using AUROC as performance measure, the XGBoost models also performed slightly better than the other models. ConclusionsAI models have potential to become valuable tools for prediction of ICP insults in advance during NIC. The fact that common off-the-shelf models, such as XGBoost, performed well in predicting ICP insults opens for new possibilities, which can lead to faster advances in the field and faster clinical implementations.
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  • Lenell, Samuel, et al. (author)
  • Cerebrovascular reactivity (PRx) and optimal cerebral perfusion pressure in elderly with traumatic brain injury
  • 2024
  • In: Acta Neurochirurgica. - : Springer Nature. - 0001-6268 .- 0942-0940. ; 166:1
  • Journal article (peer-reviewed)abstract
    • PURPOSE: Cerebral perfusion pressure (CPP) guidance by cerebral pressure autoregulation (CPA) status according to PRx (correlation mean arterial blood pressure (MAP) and intracranial pressure (ICP)) and optimal CPP (CPPopt = CPP with lowest PRx) is promising but little is known regarding this approach in elderly. The aim was to analyze PRx and CPPopt in elderly TBI patients.METHODS: A total of 129 old (≥ 65 years) and 342 young (16-64 years) patients were studied using monitoring data for MAP and ICP. CPP, PRx, CPPopt, and ΔCPPopt (difference between actual CPP and CPPopt) were calculated. Logistic regression analyses with PRx and ΔCPPopt as explanatory variables for outcome. The combined effects of PRx/CPP and PRx/ΔCPPopt on outcome were visualized as heatmaps.RESULTS: The elderly had higher PRx (worse CPA), higher CPPopt, and different temporal patterns. High PRx influenced outcome negatively in the elderly but less so than in younger patients. CPP close to CPPopt correlated to favorable outcome in younger, in contrast to elderly patients. Heatmap interaction analysis of PRx/ΔCPPopt in the elderly showed that the region for favorable outcome was centered around PRx 0 and ranging between both functioning and impaired CPA (PRx range - 0.5-0.5), and the center of ΔCPPopt was - 10 (range - 20-0), while in younger the center of PRx was around - 0.5 and ΔCPPopt closer to zero.CONCLUSIONS: The elderly exhibit higher PRx and CPPopt. High PRx influences outcome negatively in the elderly but less than in younger patients. The elderly do not show better outcome when CPP is close to CPPopt in contrast to younger patients.
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  • Rostami, Elham, 1979-, et al. (author)
  • Prognosis in moderate-severe traumatic brain injury in a Swedish cohort and external validation of the IMPACT models
  • 2022
  • In: Acta Neurochirurgica. - : Springer Nature. - 0001-6268 .- 0942-0940. ; 164:3, s. 615-624
  • Journal article (peer-reviewed)abstract
    • Background: A major challenge in management of traumatic brain injury (TBI) is to assess the heterogeneity of TBI pathology and outcome prediction. A reliable outcome prediction would have both great value for the healthcare provider, but also for the patients and their relatives. A well-known prediction model is the International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) prognostic calculator. The aim of this study was to externally validate all three modules of the IMPACT calculator on TBI patients admitted to Uppsala University hospital (UUH).Method: TBI patients admitted to UUH are continuously enrolled into the Uppsala neurointensive care unit (NICU) TBI Uppsala Clinical Research (UCR) quality register. The register contains both clinical and demographic data, radiological evaluations, and outcome assessments based on the extended Glasgow outcome scale extended (GOSE) performed at 6 months to 1 year. In this study, we included 635 patients with severe TBI admitted during 2008–2020. We used IMPACT core parameters: age, motor score, and pupillary reaction.Results: The patients had a median age of 56 (range 18–93), 142 female and 478 male. Using the IMPACT Core model to predict outcome resulted in an AUC of 0.85 for mortality and 0.79 for unfavorable outcome. The CT module did not increase AUC for mortality and slightly decreased AUC for unfavorable outcome to 0.78. However, the lab module increased AUC for mortality to 0.89 but slightly decreased for unfavorable outcome to 0.76. Comparing the predicted risk to actual outcomes, we found that all three models correctly predicted low risk of mortality in the surviving group of GOSE 2–8. However, it produced a greater variance of predicted risk in the GOSE 1 group, denoting general underprediction of risk. Regarding unfavorable outcome, all models once again underestimated the risk in the GOSE 3–4 groups, but correctly predicts low risk in GOSE 5–8.Conclusions: The results of our study are in line with previous findings from centers with modern TBI care using the IMPACT model, in that the model provides adequate prediction for mortality and unfavorable outcome. However, it should be noted that the prediction is limited to 6 months outcome and not longer time interval.
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  • Svedung-Wettervik, Teodor, et al. (author)
  • Association of Arterial Metabolic Content with Cerebral Blood Flow Regulation and Cerebral Energy Metabolism-A Multimodality Analysis in Aneurysmal Subarachnoid Hemorrhage
  • 2022
  • In: Journal of Intensive Care Medicine. - : Sage Publications. - 0885-0666 .- 1525-1489. ; 37:11, s. 1442-1450
  • Journal article (peer-reviewed)abstract
    • Background In this study, the association of the arterial content of oxygen, carbon dioxide, glucose, and lactate with cerebral pressure reactivity, energy metabolism and clinical outcome after aneurysmal subarachnoid hemorrhage (aSAH) was investigated.Methods In this retrospective study, 60 patients with aSAH, treated at the neurointensive care (NIC), Uppsala University Hospital, Sweden, between 2016 and 2021 with arterial blood gas (ABG), intracranial pressure, and cerebral microdialysis (MD) monitoring were included. The first 10 days were divided into an early phase (day 1 to 3) and a vasospasm phase (day 4 to 10).Results Higher arterial lactate was independently associated with higher/worse pressure reactivity index (PRx) in the early phase (beta = 0.32, P = .02), whereas higher pO(2) had the opposite association in the vasospasm phase (beta = -0.30, P = .04). Arterial glucose and pCO(2) were not associated with PRx. Higher arterial lactate (beta = 0.29, P = .05) was independently associated with higher MD-glucose in the vasospasm phase, whereas higher pO(2) had the opposite association in the vasospasm phase (beta = -0.33, P = .03). Arterial glucose and pCO(2) were not associated with MD-glucose. Higher pCO(2) in the early phase, lower arterial glucose in both phases, and lower arterial lactate in the vasospasm phase were associated (P < .05) with better clinical outcome.Conclusions Arterial variables associated with more vasoconstriction (higher pO(2) and lower arterial lactate) were associated with better cerebral pressure reactivity, but worse energy metabolism. In severe aSAH, when cerebral large-vessel vasospasm with exhausted distal vasodilation is common, more vasoconstriction could increase distal vasodilatory reserve and pressure reactivity, but also reduce cerebral blood flow and metabolic supply. The MD may be useful to monitor the net effects on cerebral metabolism in PRx-targeted NIC.
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  • Svedung Wettervik, Teodor, et al. (author)
  • Autoregulatory Cerebral Perfusion Pressure Insults in Traumatic Brain Injury and Aneurysmal Subarachnoid Hemorrhage : The Role of Insult Intensity and Duration on Clinical Outcome
  • 2024
  • In: Journal of Neurosurgical Anesthesiology. - : Wolters Kluwer. - 0898-4921 .- 1537-1921. ; 36:3, s. 228-236
  • Journal article (peer-reviewed)abstract
    • Background: This single-center, retrospective study investigated the outcome effect of the combined intensity and duration of differences between actual cerebral perfusion pressure (CPP) and optimal cerebral perfusion pressure (CPPopt), and also for absolute CPP, in patients with traumatic brain injury (TBI) and aneurysmal subarachnoid hemorrhage (aSAH).Methods: A total of 378 TBI and 432 aSAH patients treated in a neurointensive care unit between 2008 and 2018 with at least 24 hours of CPPopt data during the first 10 days following injury, and with 6-month (TBI) or 12-month (aSAH) extended Glasgow Outcome Scale (GOS-E) scores, were included in the study. ∆CPPopt-insults (∆CPPopt=actual CPP−CPPopt) and CPP-insults were visualized as 2-dimensional plots to highlight the combined effect of insult intensity (mm Hg) and duration (min) on patient outcome.Results: In TBI patients, a zone of ∆CPPopt ± 10 mm Hg was associated with more favorable outcome, with transitions towards unfavorable outcome above and below this zone. CPP in the range of 60 to 80 mm Hg was associated with higher GOS-E, whereas CPP outside this range was associated with lower GOS-E. In aSAH patients, there was no clear transition from higher to lower GOS-E for ∆CPPopt-insults; however, there was a transition from favorable to unfavorable outcome when CPP was <80 mm Hg.Conclusions: TBI patients with CPP close to CPPopt exhibited better clinical outcomes, and absolute CPP within the 60 to 80 mm Hg range was also associated with favorable outcome. In aSAH patients, there was no clear transition for ∆CPPopt-insults in relation to outcome, whereas generally high absolute CPP values were associated overall with favorable recovery.
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  • Svedung-Wettervik, Teodor, et al. (author)
  • Autoregulatory Management in Traumatic Brain Injury : The Role of Absolute Pressure Reactivity Index Values and Optimal Cerebral Perfusion Pressure Curve Shape
  • 2023
  • In: Journal of Neurotrauma. - : Mary Ann Liebert. - 0897-7151 .- 1557-9042. ; 40:21-22, s. 2341-2352
  • Journal article (peer-reviewed)abstract
    • The aim of this study was to investigate if the absolute pressure reactivity index (PRx) value influenced the association between cerebral perfusion pressure (CPP) and outcome and if the optimal CPP (CPPopt) curve shape influenced the association between deviation from CPPopt and outcome in traumatic brain injury (TBI). We included 383 TBI patients treated at the neurointensive care in Uppsala between 2008 and 2018 with at least 24 h of CPP data. To determine the influence of absolute PRx values on the association between absolute CPP and outcome, the percentage of monitoring time for combinations of CPP and PRx were correlated with outcome (Extended Glasgow Outcome Scale [GOS-E]) in a heatmap. To determine the association between CPP and the relatively best PRx (CPPopt), the percentage of monitoring time of ΔCPPopt (actual CPP-CPPopt) ±5 mm Hg was analyzed in relation to GOS-E. To determine the association between CPP and the relatively best PRx within a certain absolute PRx range (curve shape), both the percentage of ΔCPPopt within the absolute limits of reactivity (PRx <0.00, < 0.15, etc.) and within certain confidence intervals of PRx-deterioration (+0.025, +0.05 etc.) from CPPopt were analyzed in relation to GOS-E. The heatmap of PRx and absolute CPP versus outcome indicated that the CPP range (55-75 mm Hg) associated with favorable outcome was wider when PRx was below 0, whereas the upper CPP-threshold decreased as PRx increased. CPPopt could be calculated during 53% of the monitoring time. Higher percentage of monitoring time with ΔCPPopt ±5 mm Hg, ΔCPPopt within the reactivity-thresholds (PRx <0.30), and ΔCPPopt within the PRx-confidence interval +0.025 were all independently associated with favorable outcome in separate logistic regressions. These regressions had similar area under receiver operating curve and were not superior to a similar regression when the CPPopt-target was replaced by the percentage of monitoring time within the traditional fixed CPP-targets 60 to 70 mm Hg. Individualized CPPopt-targets exhibited a comparable outcome association as traditional CPP targets and different definitions of the best CPPopt range based on the PRx value had a limited effect on the association between deviation from CPPopt and outcome. Since CPPopt could only be calculated during half of the time, an alternative approach would be to assess the absolute PRx to anticipate a safe CPP range
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16.
  • Svedung-Wettervik, Teodor, et al. (author)
  • Cerebral Blood Flow and Oxygen Delivery in Aneurysmal Subarachnoid Hemorrhage : Relation to Neurointensive Care Targets
  • 2022
  • In: Neurocritical Care. - : Springer Nature. - 1541-6933 .- 1556-0961. ; 37:1, s. 281-292
  • Journal article (peer-reviewed)abstract
    • Background The primary aim was to determine to what extent continuously monitored neurointensive care unit (neuro-ICU) targets predict cerebral blood flow (CBF) and delivery of oxygen (CDO2) after aneurysmal subarachnoid hemorrhage. The secondary aim was to determine whether CBF and CDO2 were associated with clinical outcome. Methods In this observational study, patients with aneurysmal subarachnoid hemorrhage treated at the neuro-ICU in Uppsala, Sweden, from 2012 to 2020 with at least one xenon-enhanced computed tomography (Xe-CT) obtained within the first 14 days post ictus were included. CBF was measured with the Xe-CT and CDO2 was calculated based on CBF and arterial oxygen content. Regional cerebral hypoperfusion was defined as CBF < 20 mL/100 g/min, and poor CDO2 was defined as CDO2 < 3.8 mL O-2/100 g/min. Neuro-ICU variables including intracranial pressure (ICP), pressure reactivity index, cerebral perfusion pressure (CPP), optimal CPP, and body temperature were assessed in association with the Xe-CT. The acute phase was divided into early phase (day 1-3) and vasospasm phase (day 4-14). Results Of 148 patients, 27 had underwent a Xe-CT only in the early phase, 74 only in the vasospasm phase, and 47 patients in both phases. The patients exhibited cerebral hypoperfusion and poor CDO2 for medians of 15% and 30%, respectively, of the cortical brain areas in each patient. In multiple regressions, higher body temperature was associated with higher CBF and CDO2 in the early phase. In a similar regression for the vasospasm phase, younger age and longer pulse transit time (lower peripheral resistance) correlated with higher CBF and CDO2, whereas lower hematocrit only correlated with higher CBF but not with CDO2. ICP, CPP, and pressure reactivity index exhibited no independent association with CBF and CDO2. R-2 of these regressions were below 0.3. Lower CBF and CDO2 in the early phase correlated with poor outcome, but this only held true for CDO2 in multiple regressions. Conclusions Systemic and cerebral physiological variables exhibited a modest association with CBF and CDO2. Still, cerebral hypoperfusion and low CDO2 were common and low CDO2 was associated with poor outcome. Xe-CT imaging could be useful to help detect secondary brain injury not evident by high ICP and low CPP.
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17.
  • Svedung-Wettervik, Teodor, et al. (author)
  • Cerebral Microdialysis Monitoring of Energy Metabolism: Relation to Cerebral Blood Flow and Oxygen Delivery in Aneurysmal Subarachnoid Hemorrhage
  • 2023
  • In: Journal of Neurosurgical Anesthesiology. - : Ovid Technologies (Wolters Kluwer Health). - 0898-4921 .- 1537-1921. ; 35:4, s. 384-393
  • Journal article (peer-reviewed)abstract
    • Introduction: In this study, we investigated the roles of cerebral blood flow (CBF) and cerebral oxygen delivery (CDO2) in relation to cerebral energy metabolism after aneurysmal subarachnoid hemorrhage (aSAH).Methods: Fifty-seven adult aSAH patients treated on the neurointensive care unit at Uppsala, Sweden between 2012 and 2020, with at least 1 xenon-enhanced computed tomography (Xe-CT) scan in the first 14 days after ictus and concurrent microdialysis (MD) monitoring, were included in this retrospective study. CBF was measured globally and focally (around the MD catheter) with Xe-CT, and CDO2 calculated. Cerebral energy metabolites were measured using MD.Results: Focal ischemia (CBF <20 mL/100 g/min around the MD catheter was associated with lower median [interquartile range]) MD-glucose (1.2 [0.7 to 2.2] mM vs. 2.3 [1.3 to 3.5] mM; P=0.05) and higher MD-lactate-pyruvate (LPR) ratio (34 [29 to 66] vs. 25 [21 to 32]; P=0.02). A compensated/normal MD pattern (MD-LPR <25) was observed in the majority of patients (22/23, 96%) without focal ischemia, whereas 4 of 11 (36%) patients with a MD pattern of poor substrate supply (MD-LPR >25, MD-pyruvate <120 µM) had focal ischemia as did 5 of 20 (25%) patients with a pattern of mitochondrial dysfunction (MD-LPR >25, MD-pyruvate >120 µM) (P=0.04). Global CBF and CDO2, and focal CDO2, were not associated with the MD variables.Conclusions: While MD is a feasible tool to study cerebral energy metabolism, its validity is limited to a focal area around the MD catheter. Cerebral energy disturbances were more related to low CBF than to low CDO2. Considering the high rate of mitochondrial dysfunction, treatments that increase CBF but not CDO2, such as hemodilution, may still benefit glucose delivery to drive anaerobic metabolism.
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18.
  • Svedung-Wettervik, Teodor, et al. (author)
  • Females Exhibit Better Cerebral Pressure Autoregulation, Less Mitochondrial Dysfunction, and Reduced Excitotoxicity after Severe Traumatic Brain Injury
  • 2022
  • In: Journal of Neurotrauma. - : Mary Ann Liebert. - 0897-7151 .- 1557-9042. ; 39:21-22, s. 1507-1517
  • Journal article (peer-reviewed)abstract
    • The aim of the study was to investigate sex-related differences in intracranial pressure (ICP) dynamics, cerebral pressure autoregulation (PRx55-15), cerebral energy metabolism, and clinical outcome after severe traumatic brain injury (TBI). One-hundred sixty-nine adult patients with TBI, treated at the Neurointensive Care (NIC) Unit at Uppsala University Hospital between 2008 and 2020 with ICP and cerebral microdialysis (MD) monitoring were included. Of the 169 patients with TBI, 131 (78%) were male and 38 (22%) female. Male patients were more often injured by motor vehicle accidents and less often by bicycle accidents (p < 0.05). There were otherwise no differences in age, neurological status at admission, and types of intracranial hemorrhages between the sexes. The percent of monitoring time with ICP above 20 mm Hg and cerebral perfusion pressure (CPP) below 60 mm Hg were similar for both sexes. Males exhibited more disturbed cerebral pressure autoregulation (PRx55-15 [mean +/- standard deviation (SD)]; 0.28 +/- 0.18 vs. 0.17 +/- 0.23, p < 0.05) on day 1, worse cerebral energy metabolism (MD-lactate-/pyruvate-ratio [median (interquartile range)]; 25 [19-31] vs. 20 [17-25], p < 0.01) and mitochondrial dysfunction (higher burden of MD-lactate-/pyruvate-ratio >25 and MD-pyruvate >120 mu M [median (interquartile range)]; 13 [0-58] % vs. 3 [0-17] %, p < 0.05) on days 2 to 5, increased excitotoxicity (MD-glutamate median [interquartile range]; 9 [4-32] mu M vs. 5 [3-10] mu M, p < 0.05) on days 2 to 5, and higher biomarker levels of cellular injury (MD-glycerol median [interquartile range]; 103 [66-193] mu M vs. 68 [49-106] mu M, p < 0.01) most pronounced on days 6 to 10. There was no difference in mortality or the degree of favorable outcome between the sexes.Altogether, females exhibited more favorable cerebral physiology post-TBI, particularly better mitochondrial function and reduced excitotoxicity, but this did not translate into better clinical outcome compared with males. Future studies are needed to further explore potential sex differences in secondary injury mechanisms in TBI.
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19.
  • Svedung-Wettervik, Teodor, et al. (author)
  • Higher Intracranial Pressure Variability is Associated with Lower Cerebrovascular Resistance in Aneurysmal Subarachnoid Hemorrhage
  • 2023
  • In: Journal of clinical monitoring and computing. - : Springer Nature. - 1387-1307 .- 1573-2614. ; 37:1, s. 319-326
  • Journal article (peer-reviewed)abstract
    • Higher intracranial pressure variability (ICPV) has been associated with a more favorable cerebral energy metabolism, lower rate of delayed ischemic neurologic deficits, and more favorable outcome in aneurysmal subarachnoid hemorrhage (aSAH). We have hypothesized that higher ICPV partly reflects more compliant and active cerebral vessels. In this study, the aim was to further test this by investigating if higher ICPV was associated with lower cerebrovascular resistance (CVR) and higher cerebral blood flow (CBF) after aSAH. In this observational study, 147 aSAH patients were included, all of whom had been treated in the Neurointensive Care (NIC) Unit, Uppsala, Sweden, 2012–2020. They were required to have had ICP monitoring and at least one xenon-enhanced computed tomography (Xe-CT) scan to study cortical CBF within the first 2 weeks post-ictus. CVR was defined as the cerebral perfusion pressure in association with the Xe-CT scan divided by the concurrent CBF. ICPV was defined over three intervals: subminute (ICPV-1m), 30-min (ICPV-30m), and 4 h (ICPV-4h). The first 14 days were divided into early (days 1–3) and vasospasm phase (days 4–14). In the vasospasm phase, but not in the early phase, higher ICPV-4h (β =  − 0.19, p < 0.05) was independently associated with a lower CVR in a multiple linear regression analysis and with a higher global cortical CBF (r = 0.19, p < 0.05) in a univariate analysis. ICPV-1m and ICPV-30m were not associated with CVR or CBF in any phase. This study corroborates the hypothesis that higher ICPV, at least in the 4-h interval, is favorable and may reflect more compliant and possibly more active cerebral vessels.
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20.
  • Svedung Wettervik, Teodor, et al. (author)
  • ICP, CPP, and PRx in traumatic brain injury and aneurysmal subarachnoid hemorrhage : association of insult intensity and duration with clinical outcome
  • 2023
  • In: Journal of Neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 138:2, s. 446-453
  • Journal article (peer-reviewed)abstract
    • OBJECTIVEThe primary aim of this study was to determine the combined effect of insult intensity and duration of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and pressure reactivity index (PRx) on outcome measured with the Glasgow Outcome Scale–Extended (GOS-E) in patients with traumatic brain injury (TBI) or aneurysmal subarachnoid hemorrhage (aSAH).METHODSThis observational study included all TBI and aSAH patients treated in the neurointensive care unit in Uppsala, Sweden, 2008–2018, with at least 24 hours of ICP monitoring during the first 10 days following injury and available long-term clinical outcome data. ICP, CPP, and PRx insults were visualized as 2D plots to highlight the effects of both insult intensity and duration on patient outcome.RESULTSOf 950 included patients, 436 were TBI and 514 aSAH patients. The TBI patients were younger, more often male, and exhibited worse neurological status at admission, but recovered more favorably than the aSAH patients. There was a transition from good to poor outcome with ICP above 15–20 mm Hg in both TBI and aSAH. The two diagnoses had opposite CPP patterns. In TBI patients, CPP episodes at or below 80 mm Hg were generally favorable, whereas CPP episodes above 80 mm Hg were favorable in the aSAH patients. In the TBI patients there was a transition from good to poor outcome when PRx exceeded zero, but no evident transition was found in the aSAH cohort.CONCLUSIONSThe insult intensity and duration plots formulated in this study illustrate the similarities and differences between TBI and aSAH patients. In particular, aSAH patients may benefit from much higher CPP targets than TBI patients.
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21.
  • Svedung Wettervik, Teodor, et al. (author)
  • ICP, PRx, CPP, and ∆CPPopt in pediatric traumatic brain injury : the combined effect of insult intensity and duration on outcome
  • 2023
  • In: Child's Nervous System. - : Springer. - 0256-7040 .- 1433-0350. ; 39:9, s. 2459-2466
  • Journal article (peer-reviewed)abstract
    • PurposeThe aim was to investigate the combined effect of insult intensity and duration, regarding intracranial pressure (ICP), pressure reactivity index (PRx), cerebral perfusion pressure (CPP), and optimal CPP (CPPopt), on clinical outcome in pediatric traumatic brain injury (TBI).MethodThis observational study included 61 pediatric patients with severe TBI, treated at the Uppsala University Hospital, between 2007 and 2018, with at least 12 h of ICP data the first 10 days post-injury. ICP, PRx, CPP, and increment CPPopt (actual CPP-CPPopt) insults were visualized as 2-dimensional plots to illustrate the combined effect of insult intensity and duration on neurological recovery.ResultsThis cohort was mostly adolescent pediatric TBI patients with a median age at 15 (interquartile range 12-16) years. For ICP, brief episodes (minutes) above 25 mmHg and slightly longer episodes (20 min) of ICP 20-25 mmHg correlated with unfavorable outcome. For PRx, brief episodes above 0.25 as well as slightly lower values (around 0) for longer periods of time (30 min) were associated with unfavorable outcome. For CPP, there was a transition from favorable to unfavorable outcome for CPP below 50 mmHg. There was no association between high CPP and outcome. For increment CPPopt, there was a transition from favorable to unfavorable outcome when increment CPPopt went below -10 mmHg. No association was found for positive increment CPPopt values and outcome.ConclusionsThis visualization method illustrated the combined effect of insult intensity and duration in relation to outcome in severe pediatric TBI, supporting previous notions to avoid high ICP and low CPP for longer episodes of time. In addition, higher PRx for longer episodes of time and CPP below CPPopt more than -10 mmHg were associated with worse outcome, indicating a potential role for autoregulatory-oriented management in pediatric TBI.
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22.
  • Svedung-Wettervik, Teodor, et al. (author)
  • Intracranial lesion features in moderate-to-severe traumatic brain injury : relation to neurointensive care variables and clinical outcome
  • 2023
  • In: Acta Neurochirurgica. - : Springer. - 0001-6268 .- 0942-0940. ; 165, s. 2389-2398
  • Journal article (peer-reviewed)abstract
    • Background: The primary aim was to determine the association of intracranial hemorrhage lesion type, size, mass effect, and evolution with the clinical course during neurointensive care and long-term outcome after traumatic brain injury (TBI).Methods: In this observational, retrospective study, 385 TBI patients treated at the neurointensive care unit at Uppsala University Hospital, Sweden, were included. The lesion type, size, mass effect, and evolution (progression on the follow-up CT) were assessed and analyzed in relation to the percentage of secondary insults with intracranial pressure > 20 mmHg, cerebral perfusion pressure < 60 mmHg, and cerebral pressure autoregulatory status (PRx) and in relation to Glasgow Outcome Scale-Extended.Results: A larger epidural hematoma (p < 0.05) and acute subdural hematoma (p < 0.001) volume, greater midline shift (p < 0.001), and compressed basal cisterns (p < 0.001) correlated with craniotomy surgery. In multiple regressions, presence of traumatic subarachnoid hemorrhage (p < 0.001) and intracranial hemorrhage progression on the follow-up CT (p < 0.01) were associated with more intracranial pressure-insults above 20 mmHg. In similar regressions, obliterated basal cisterns (p < 0.001) were independently associated with higher PRx. In a multiple regression, greater acute subdural hematoma (p < 0.05) and contusion (p < 0.05) volume, presence of traumatic subarachnoid hemorrhage (p < 0.01), and obliterated basal cisterns (p < 0.01) were independently associated with a lower rate of favorable outcome.Conclusions: The intracranial lesion type, size, mass effect, and evolution were associated with the clinical course, cerebral pathophysiology, and outcome following TBI. Future efforts should integrate such granular data into more sophisticated machine learning models to aid the clinician to better anticipate emerging secondary insults and to predict clinical outcome.
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23.
  • Svedung-Wettervik, Teodor, et al. (author)
  • Intracranial pressure- and cerebral perfusion pressure threshold-insults in relation to cerebral energy metabolism in aneurysmal subarachnoid hemorrhage
  • 2022
  • In: Acta Neurochirurgica. - : Springer Nature. - 0001-6268 .- 0942-0940. ; 164:4, s. 1001-1014
  • Journal article (peer-reviewed)abstract
    • Background The aim was to investigate the association between intracranial pressure (ICP)- and cerebral perfusion pressure (CPP) threshold-insults in relation to cerebral energy metabolism and clinical outcome after aneurysmal subarachnoid hemorrhage (aSAH). Methods In this retrospective study, 75 aSAH patients treated in the neurointensive care unit, Uppsala, Sweden, 2008-2018, with ICP and cerebral microdialysis (MD) monitoring were included. The first 10 days were divided into early (day 1-3), early vasospasm (day 4-6.5), and late vasospasm phase (day 6.5-10). The monitoring time (%) of ICP insults (> 20 mmHg and > 25 mmHg), CPP insults (< 60 mmHg, < 70 mmHg, < 80 mmHg, and < 90 mmHg), and autoregulatory CPP optimum (CPPopt) insults ( increment CPPopt = CPP-CPPopt < - 10 mmHg, increment CPPopt > 10 mmHg, and within the optimal interval increment CPPopt +/- 10 mmHg) were calculated in each phase. Results Higher percent of ICP above the 20 mmHg and 25 mmHg thresholds correlated with lower MD-glucose and increased MD-lactate-pyruvate ratio (LPR), particularly in the vasospasm phases. Higher percentage of CPP below all four thresholds (60/70/80//90 mmHg) also correlated with a MD pattern of poor cerebral substrate supply (MD-LPR > 40 and MD-pyruvate < 120 mu M) in the vasospasm phase and higher burden of CPP below 60 mmHg was independently associated with higher MD-LPR in the late vasospasm phase. Higher percentage of CPP deviation from CPPopt did not correlate with worse cerebral energy metabolism. Higher burden of CPP-insults below all fixed thresholds in both vasospasm phases were associated with worse clinical outcome. The percentage of ICP-insults and CPP close to CPPopt were not associated with clinical outcome. Conclusions Keeping ICP below 20 mmHg and CPP at least above 60 mmHg may improve cerebral energy metabolism and clinical outcome.
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24.
  • Svedung Wettervik, Teodor, et al. (author)
  • Intracranial Pressure Variability : A New Potential Metric of Cerebral Ischemia and Energy Metabolic Dysfunction in Aneurysmal Subarachnoid Hemorrhage?
  • 2023
  • In: Journal of Neurosurgical Anesthesiology. - : Wolters Kluwer. - 0898-4921 .- 1537-1921. ; 35:2, s. 208-214
  • Journal article (peer-reviewed)abstract
    • Background: It was recently reported that lower intracranial pressure variability (ICPV) is associated with delayed ischemic neurological deficits and unfavorable outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). In this study, we aimed to determine whether lower ICPV also correlated with worse cerebral energy metabolism after aSAH.Methods: A total of 75 aSAH patients treated in the neurointensive care unit at Uppsala University Hospital, Sweden between 2008 and 2018 and with both intracranial pressure and cerebral microdialysis (MD) monitoring during the first 10 days after ictus were included in this retrospective study. ICPV was calculated with a bandpass filter limited to intracranial pressure slow waves with a wavelength of 55 to 15 seconds. Cerebral energy metabolites were measured hourly with MD. The monitoring period was divided into 3 phases; early (days 1 to 3), early vasospasm (days 4 to 6.5), and late vasospasm (days 6.5 to 10).Results: Lower ICPV was associated with lower MD-glucose in the late vasospasm phase, lower MD-pyruvate in the early vasospasm phases, and higher MD-lactate-pyruvate ratio (LPR) in the early and late vasospasm phases. Lower ICPV was associated with poor cerebral substrate supply (LPR >25 and pyruvate <120 µM) rather than mitochondrial failure (LPR >25 and pyruvate >120 µM). There was no association between ICPV and delayed ischemic neurological deficit, but lower ICPV in both vasospasm phases correlated with unfavorable outcomes.Conclusion: Lower ICPV was associated with an increased risk for disturbed cerebral energy metabolism and worse clinical outcomes in aSAH patients, possibly explained by a vasospasm-related decrease in cerebral blood volume dynamics and cerebral ischemia.
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25.
  • Svedung Wettervik, Teodor, et al. (author)
  • Low intracranial pressure variability is associated with delayed cerebral ischemia and unfavorable outcome in aneurysmal subarachnoid hemorrhage
  • 2022
  • In: Journal of clinical monitoring and computing. - : Springer Nature. - 1387-1307 .- 1573-2614. ; 36:2, s. 569-578
  • Journal article (peer-reviewed)abstract
    • PurposeHigh intracranial pressure variability (ICPV) is associated with favorable outcome in traumatic brain injury, by mechanisms likely involving better cerebral blood flow regulation. However, less is known about ICPV in aneurysmal subarachnoid hemorrhage (aSAH). In this study, we investigated the explanatory variables for ICPV in aSAH and its association with delayed cerebral ischemia (DCI) and clinical outcome.MethodsIn this retrospective study, 242 aSAH patients, treated at the neurointensive care, Uppsala, Sweden, 2008–2018, with ICP monitoring the first ten days post-ictus were included. ICPV was evaluated on three time scales: (1) ICPV-1 m—ICP slow wave amplitude of wavelengths between 55 and 15 s, (2) ICPV-30 m—the deviation from the mean ICP averaged over 30 min, and (3) ICPV-4 h—the deviation from the mean ICP averaged over 4 h. The ICPV measures were analyzed in the early phase (day 1–3), in the early vasospasm phase (day 4–6.5), and the late vasospasm phase (day 6.5–10).ResultsHigh ICPV was associated with younger age, reduced intracranial pressure/volume reserve (high RAP), and high blood pressure variability in multiple linear regression analyses for all ICPV measures. DCI was associated with reduced ICPV in both vasospasm phases. High ICPV-1 m in the post-ictal early phase and the early vasospasm phase predicted favorable outcome in multiple logistic regressions, whereas ICPV-30 m and ICPV-4 h in the late vasospasm phase had a similar association.ConclusionsHigher ICPV may reflect more optimal cerebral vessel activity, as reduced values are associated with an increased risk of DCI and unfavorable outcome after aSAH.
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26.
  • Svedung-Wettervik, Teodor, et al. (author)
  • Temperature Changes in Poor-Grade Aneurysmal Subarachnoid Hemorrhage : Relation to Injury Pattern, Intracranial Pressure Dynamics, Cerebral Energy Metabolism, and Clinical Outcome
  • 2023
  • In: Neurocritical Care. - : Humana Press. - 1541-6933 .- 1556-0961. ; 39, s. 145-154
  • Journal article (peer-reviewed)abstract
    • Background: The aim was to study the course of body temperature in the acute phase of poor-grade aneurysmal subarachnoid hemorrhage (aSAH) in relation to the primary brain injury, cerebral physiology, and clinical outcome.Methods: In this observational study, 166 patients with aSAH treated at the neurosurgery department at Uppsala University Hospital in Sweden between 2008 and2018 with temperature, intracranial pressure (ICP), and microdialysis (MD) monitoring were included. The first 10 days were divided into the early phase (days 1-3) and the vasospasm phase (days 4-10).Results: Normothermia (temperature = 36-38 degrees C) was most prevalent in the early phase. A lower mean temperature at this stage was univariately associated with a worse primary brain injury, with higher Fisher grade and higher MD glycerol concentration, as well as a worse neurological recovery at 1 year. There was otherwise no association between temperature and cerebral physiological variables in the early phase. There was a transition toward an increased burden of hyperthermia (temperature > 38 degrees C) in the vasospasm phase. This was associated with concurrent infections but not with neurological or radiological injury severity at admission. Elevated temperature was associated with higher MD pyruvate concentration, lower rate of an MD pattern indicative of ischemia, and higher rate of poor neurological recovery at 1 year. There was otherwise no association between temperature and cerebral physiological variables in the vasospasm phase. The associations between temperature and clinical outcome did not hold true in multiple logistic regression analyses.Conclusions: Spontaneously low temperature in the early phase reflected a worse primary brain injury and indicated a worse outcome prognosis. Hyperthermia was common in the vasospasm phase and was more related to infections than primary injury severity but also with a more favorable energy metabolic pattern with better substrate supply, possibly related to hyperemia.
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27.
  • Velle, Fartein, et al. (author)
  • Cerebral pressure autoregulation and optimal cerebral perfusion pressure during neurocritical care of children with traumatic brain injury
  • 2023
  • In: Journal of Neurosurgery. - : American Association of Neurological Surgeons (AANS). - 1933-0707 .- 1933-0715. ; 31:5, s. 503-513
  • Journal article (peer-reviewed)abstract
    • OBJECTIVEThe management of cerebral perfusion pressure (CPP) is a challenge in children with traumatic brain injury (TBI) because the normal blood pressure is age dependent and the role of cerebral pressure autoregulation (CPA) is unclear. In this study, the authors aimed to examine the pressure reactivity index (PRx), CPP, optimal CPP (CPPopt), and deviations from CPPopt (ΔCPPopt) in a series of children with TBI generally and regarding age relations, temporal changes, and the influence on outcome.METHODSIntracranial pressure (ICP) and mean arterial pressure (MAP) monitoring data were collected during neurointensive care in 57 children who sustained a TBI and were ≤ 17 years of age. CPP, PRx, CPPopt, and ΔCPPopt (actual CPP − CPPopt) were calculated. Clinical outcomes at 6 months postinjury were dichotomized into favorable outcomes (Glasgow Outcome Scale [GOS] score 4 or 5) and unfavorable outcomes (GOS scores 1–3).RESULTSThe median patient age was 15 (range 0.5–17) years, and the median Glasgow Coma Scale motor score at admission was 5 (range 2–5). Forty-nine (86%) of the 57 patients had favorable outcomes. For the entire group, lower PRx (better preserved CPA) was associated with a more favorable outcome (p = 0.023, ANCOVA adjusted for age). When the children were divided into age groups, this finding was statistically significant in children ≤ 15 years of age (p = 0.016), but not in children ≥ 16 years (p = 0.528). In children ≤ 15 years, a lower proportion of time with ΔCPPopt < −10% was significantly associated with a favorable outcome (p = 0.038), but not in the older age group. Temporal analysis indicated that PRx was higher (more impaired CPA) from day 4 and CPPopt was higher from day 6 in the unfavorable outcome group compared with the favorable outcome group, although those findings were not significant.CONCLUSIONSImpaired CPA is related to poor outcome, particularly in children ≤ 15 years of age. In that age group, actual CPP below the CPPopt level contributed significantly to unfavorable outcome, while levels close to or above the CPPopt were unrelated to outcome. CPPopt appears to be higher during the time period when CPA is most impaired.
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28.
  • Velle, Fartein, et al. (author)
  • The effects of cerebral pressure autoregulation status and CPP levels on cerebral metabolism in pediatric traumatic brain injury
  • 2024
  • In: Acta Neurochirurgica. - : Springer. - 0001-6268 .- 0942-0940. ; 166:1
  • Journal article (peer-reviewed)abstract
    • BackgroundCerebral perfusion pressure (CPP) management in the developing child with traumatic brain injury (TBI) is challenging. The pressure reactivity index (PRx) may serve as marker of cerebral pressure autoregulation (CPA) and optimal CPP (CPPopt) may be assessed by identifying the CPP level with best (lowest) PRx. To evaluate the potential of CPPopt guided management in children with severe TBI, cerebral microdialysis (CMD) monitoring levels of lactate and the lactate/pyruvate ratio (LPR) (indicators of ischemia) were related to actual CPP levels, autoregulatory state (PRx) and deviations from CPPopt (ΔCPPopt).MethodsRetrospective study of 21 children ≤ 17 years with severe TBI who had both ICP and CMD monitoring were included. CPP, PRx, CPPopt and ΔCPPopt where calculated, dichotomized and compared with CMD lactate and lactate-pyruvate ratio.ResultsMedian age was 16 years (range 8–17) and median Glasgow coma scale motor score 5 (range 2–5). Both lactate (p = 0.010) and LPR (p =  < 0.001) were higher when CPP ≥ 70 mmHg than when CPP < 70. When PRx ≥ 0.1 both lactate and LPR were higher than when PRx < 0.1 (p =  < 0.001). LPR was lower (p = 0.012) when CPPopt ≥ 70 mmHg than when CPPopt < 70, but there were no differences in lactate levels. When ΔCPPopt > 10 both lactate (p = 0.026) and LPR (p = 0.002) were higher than when ΔCPPopt < –10.ConclusionsIncreased levels of CMD lactate and LPR in children with severe TBI appears to be related to disturbed CPA (PRx). Increased lactate and LPR also seems to be associated with actual CPP levels ≥ 70 mmHg. However, higher lactate and LPR values were also seen when actual CPP was above CPPopt. Higher CPP appears harmful when CPP is above the upper limit of pressure autoregulation. The findings indicate that CPPopt guided CPP management may have potential in pediatric TBI.
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29.
  • Abu Hamdeh, Sami, et al. (author)
  • Intracranial pressure elevations in diffuse axonal injury : association with nonhemorrhagic MR lesions in central mesencephalic structures
  • 2019
  • In: Journal of Neurosurgery. - 0022-3085 .- 1933-0693. ; 131:2, s. 604-611
  • Journal article (peer-reviewed)abstract
    • Objective: Increased intracranial pressure (ICP) in patients with severe traumatic brain injury (TBI) with diffuse axonal injury (DAI) is not well defined. This study investigated the occurrence of increased ICP and whether clinical factors and lesion localization on MRI were associated with increased ICP in patients with DAI.Methods: Fifty-two patients with severe TBI (median age 24 years, range 9–61 years), who had undergone ICP monitoring and had DAI on MRI, as determined using T2*-weighted gradient echo, susceptibility-weighted imaging, and diffusion-weighted imaging (DWI) sequences, were enrolled. The proportion of good monitoring time (GMT) with ICP > 20 mm Hg during the first 120 hours postinjury was calculated and associations with clinical and MRI-related factors were evaluated using linear regression.Results: All patients had episodes of ICP > 20 mm Hg. The mean proportion of GMT with ICP > 20 mm Hg was 5%, and 27% of the patients (14/52) spent more than 5% of GMT with ICP > 20 mm Hg. The Glasgow Coma Scale motor score at admission (p = 0.04) and lesions on DWI sequences in the substantia nigra and mesencephalic tegmentum (SN-T, p = 0.001) were associated with the proportion of GMT with ICP > 20 mm Hg. In multivariable linear regression, lesions on DWI sequences in SN-T (8% of GMT with ICP > 20 mm Hg, 95% CI 3%–13%, p = 0.004) and young age (−0.2% of GMT with ICP > 20 mm Hg, 95% CI −0.07% to −0.3%, p = 0.002) were associated with increased ICP.Conclusions: Increased ICP occurs in approximately one-third of patients with severe TBI who have DAI. Age and lesions on DWI sequences in the central mesencephalon (i.e., SN-T) are associated with elevated ICP. These findings suggest that MR lesion localization may aid prediction of increased ICP in patients with DAI.Abbreviations: ADC = apparent diffusion coefficient; CPP = cerebral perfusion pressure; DAI = diffuse axonal injury; DWI = diffusion-weighted imaging; EVD = external ventricular drain; GCS = Glasgow Coma Scale; GMT = good monitoring time; GOSE = Glasgow Outcome Scale–Extended; ICC = intraclass correlation coefficient; ICP = intracranial pressure; MAP = mean arterial blood pressure; NICU = neurointensive care unit; SN-T = substantia nigra and mesencephalic tegmentum; SWI = susceptibility-weighted imaging; TBI = traumatic brain injury; T2*GRE = T2*-weighted gradient echo.
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30.
  • Abu Hamdeh, Sami, et al. (author)
  • Intracranial pressure elevations in diffuse axonal injury are associated with non-hemorrhagic MR lesions in central mesencephalic structures
  • Journal article (other academic/artistic)abstract
    • Objective: Increased intracranial pressure (ICP) in severe traumatic brain injury (TBI) patients with diffuse axonal injury (DAI) is not well defined. This study investigated the occurrence of increased ICP and whether clinical factors and lesion localization on MRI were associated with increased ICP in DAI patients.Methods: Fifty-two severe TBI patients (median 24, range 9-61 years), with ICP-monitoring and DAI on MRI, using T2*-weighted gradient echo, susceptibility-weighted and diffusion-weighted (DW) sequences, were enrolled. Proportion of good monitoring time (GMT) with ICP>20 mmHg during the first 120 hours post-injury was calculated and associations with clinical and MRI-related factors were evaluated using linear regression. Results: All patients had episodes of ICP>20 mmHg. The mean proportion of GMT with ICP>20 mmHg was 5% and 27% of the patients (14/52) had more than 5% of GMT with ICP>20 mmHg. Glasgow Coma Scale motor score at admission (P=0.04) and lesions on DW images in the substantia nigra and mesencephalic tegmentum (SN-T, P=0.001) were associated with the proportion of GMT with ICP>20 mmHg. In multivariate linear regression, lesions on DW images in SN-T (8% of GMT with ICP>20 mmHg, 95% CI 3–13%, P=0.004) and young age (-0.2% of GMT with ICP>20 mmHg, 95% CI -0.07–-0.3%, P=0.0008) were associated with increased ICP.   Conclusions: Increased ICP occurs in ~1/3 of severe TBI patients with DAI. Age and lesions on DW images in the central mesencephalon (SN-T) associate with elevated ICP. These findings suggest that MR lesion localization may aid prediction of increased ICP in DAI patients.
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31.
  • Borota, Ljubisa, et al. (author)
  • Dual lumen balloon catheter - An effective substitute for two single lumen catheters in treatment of vascular targets with challenging anatomy
  • 2018
  • In: Journal of clinical neuroscience. - : Elsevier BV. - 0967-5868 .- 1532-2653. ; 51, s. 91-99
  • Journal article (peer-reviewed)abstract
    • The aim of this study was to describe our experience in the treatment of various pathological conditions of the cranial and spinal blood vessels and hypervascularized lesions using dual lumen balloon catheters. Twenty-five patients were treated with endovascular techniques: two with vasospasm of cerebral blood vessels caused by subarachnoid hemorrhage, one with a hypervascularized metastasis in the vertebral body, two with spinal dural fistula, four with cerebral dural fistula, three with cerebral arteriovenous malformations, and 13 with aneurysms. The dual lumen balloon catheters were used for remodeling of the coil mesh, injection of various liquid embolic agents, particles and nimodipine, for the prevention of reflux and deployment of coils and stents. The diameter of catheterized blood vessels varied from 0.7 mm to 4 mm. Two complications occurred: perforation of an aneurysm in one case and gluing of the tip of balloon catheter by embolic material in another case. All other interventions were uneventful, and therapeutic goals were achieved in all cases except in the case with gluing of the tip of balloon catheter. The balloons effectively prevented reflux regardless of the type of the embolic material and diameter of blood vessel. The results of our study show that dual lumen balloon catheters allow complex interventions in the narrow cerebral and spinal blood vessels where the safe use of two single lumen catheters is either limited or impossible.
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32.
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33.
  • Clausen, Fredrik, et al. (author)
  • Interstitial F2-Isoprostane 8-Iso-PGF2α As a Biomarker of Oxidative Stress after Severe Human Traumatic Brain Injury
  • 2012
  • In: Journal of Neurotrauma. - : Mary Ann Liebert Inc. - 0897-7151 .- 1557-9042. ; 29:5, s. 766-775
  • Journal article (peer-reviewed)abstract
    • Oxidative stress is a major contributor to the secondary injury process after experimental traumatic brain injury (TBI). The importance of oxidative stress in the pathobiology of human TBI is largely unknown. The F(2)-isoprostane 8-iso-prostaglandin F(2α) (8-iso-PGF(2α)), synthesized in vivo through non-enzymatic free radical catalyzed peroxidation of arachidonic acid, is a widely used biomarker of oxidative stress in multiple disease states, including TBI and cerebral ischemia/reperfusion. Our hypothesis is that harvesting of biomarkers directly in the injured brain by cerebral microdialysis (MD) is advantageous because of its high spatial and temporal resolution compared to blood or cerebrospinal fluid sampling. The aim of this study was to test the feasibility of measuring 8-iso-PGF(2α) in MD, ventricular cerebrospinal fluid (vCSF), and plasma samples collected from patients with severe TBI, and to compare the MD signals with MD-glycerol, implicated as a biomarker of oxidative stress, as well as MD-glutamate, a biomarker of excitotoxicity. Six patients (4 men, 2 women) were included in the study, three of whom had a focal/mixed TBI, and three a diffuse axonal injury (DAI). Following the bedside analysis of routine MD biomarkers (glucose, lactate:pyruvate ratio, glycerol, and glutamate), two 12-h MD samples per day were used to analyze 8-iso-PGF(2α) from 24 h up to 8 days post-injury. The interstitial levels of 8-iso-PGF(2α) were markedly higher than the levels obtained from plasma and vCSF (p<0.05), supporting our hypothesis. The MD-8-iso-PGF(2α) levels correlated strongly (p<0.05) with MD-glycerol and MD-glutamate, which are widely used biomarkers of membrane phospholipid degradation/oxidative stress and excitotoxicity, respectively. This study demonstrates the feasibility of analyzing 8-iso-PGF(2α) in MD samples from the human brain. Our results support a close relationship between oxidative stress and excitotoxicity following human TBI. MD-8-iso-PGF(2α) in combination with MD-glycerol may be useful biomarkers of oxidative stress in the neurointensive care setting.
  •  
34.
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35.
  • Clausen, Fredrik, et al. (author)
  • Oxygen free radical-dependent activation of extracellular signal-regulated kinase mediates apoptosis-like cell death after traumatic brain injury
  • 2004
  • In: Journal of Neurotrauma. ; 21:9, s. 1168-1182
  • Journal article (peer-reviewed)abstract
    • Mitogen-activated protein kinase (MAPK) cascades are membrane-to-nucleus signaling modules that recently have been implicated as mediators of cellular injury. In this study, we investigated the involvement of the MAP kinase p44/p42 (extracellular signal-regulated kinase [ERK1/2]) in traumatic brain injury (TBI) in rats. There was a strong increase in activated, phosphorylated ERK 1/2 (p-ERK 1/2) protein at 10 min up to 24 h after the injury. Expression of p-ERK occurred in cells identified as neurons, astrocytes, and microglia. Most of the cells expressing p-ERK were TUNEL positive at later time points. Treatment with the MEK inhibitor U0126 or the free radical scavenger S-PBN, both with neuroprotective properties in TBI, attenuated the early activation of ERK and resulted in less activation of caspase-3 and subsequent DNA fragmentation. Post-treatment with U0126 resulted in a significant decrease (-60%) in cortical cavity size and cortical atrophy at 2 weeks after trauma. Overall, the results suggest that ERK activation is initiated by increased oxygen radical activity and that overactivation of ERK sets off secondary cell death mechanisms in TBI. Clinical studies are warranted to evaluate the concept of MEK inhibition in head-injured patients.
  •  
36.
  • Clausen, Fredrik, et al. (author)
  • T Lymphocyte trafficking : A novel target for neuroprotection in traumatic brain injury
  • 2007
  • In: Journal of Neurotrauma. - : Mary Ann Liebert Inc. - 0897-7151 .- 1557-9042. ; 24:8, s. 1295-1307
  • Journal article (peer-reviewed)abstract
    • Infiltration of T lymphocytes is a key feature in transplant rejection and in several autoimmune disorders, but the role of T lymphocytes in traumatic brain injury (TBI) is largely unknown. Here we studied trafficking of immune cells in the brain after experimental TBI. We found that scavenging of reactive oxygen species (ROS) at the endothelial level dramatically reduced the infiltration of activated T lymphocytes. Immune cell infiltration was studied 12 h to 7 days after controlled cortical contusion in rats by ex vivo propagation of T lymphocytes (TcR+, CD8+), neutrophils (MPO+), and macrophages/microglia (ED-1+) from biopsies taken from injured cortex and analyzed by flow cytometry, as well as by quantitative immunohistochemistry. T lymphocyte and neutrophil infiltration peaked at 24 h and macrophages/microglia at 7 days post-injury. Pretreatment with 2-sulfophenyl-N-tert-butyl nitrone (S-PBN) produced a dramatic reduction of TcR+ T lymphocytes and a significantly smaller attenuation of neutrophil infiltration at 24 h post-injury, but did not affect CD8+ T lymphocytes or macrophages/microglia. S-PBN significantly reduced the expression of the endothelial adhesion molecules ICAM-1 and VCAM at 24 h for following TBI. We conclude that ROS inhibition at the endothelial level influenced T lymphocyte and neutrophil infiltration following TBI. We submit that the reduction of T lymphocyte infiltration is a key feature in improving TBI outcome after S-PBN treatment. Our data suggest that targeting T lymphocyte trafficking to the injured brain at the microvascular level is a novel concept of neuroprotection in TBI and warrants further exploration.
  •  
37.
  • Clausen, Fredrik, 1973-, et al. (author)
  • The nitrone free radical scavenger NXY-059 is neuroprotective when administered after traumatic brain injury in the rat
  • 2008
  • In: Journal of Neurotrauma. - : Mary Ann Liebert, Inc.. - 0897-7151 .- 1557-9042. ; 25:12, s. 1449-1457
  • Journal article (peer-reviewed)abstract
    • Reactive oxygen species (ROS) are important contributors to the secondary injury cascade following traumatic brain injury (TBI), and ROS inhibition has consistently been shown to be neuroprotective following experimental TBI. NXY-059, a nitrone free radical trapping compound, has been shown to be neuroprotective in models of ischemic stroke but has not been evaluated in experimental TBI. In the present study, a continuous 24-h intravenous infusion of NXY-059 or vehicle was initiated 30min following a severe lateral fluid percussion brain injury (FPI) in adult rats (n=22), and histological and behavioral outcomes were evaluated. Sham-injured animals (n=22) receiving identical drug infusion were used as controls. Visuospatial learning was evaluated in the Morris water maze at post-injury days 11–14, followed by a probe trial (memory test) at day 18. The animals were sacrificed at day 18, and loss of hemispheric brain tissue was measured in microtubule-associated protein (MAP)–2stained sections. Brain-injured, NXY-059-treated animals showed a significant reduction of visuospatial learning deficits when compared to the brain-injured, vehicle-treated control animals (p<0.05). NXY-059-treated animals significantly reduced the loss of hemispheric tissue compared to brain-injured controls (43.0±11mm3 versus 74.4±19mm3, respectively; p<0.01). The results show that post-injury treatment with NXY-059 significantly attenuated the loss of injured brain tissue and improved cognitive outcome, suggesting a major role for ROS in the pathophysiology of TBI.
  •  
38.
  •  
39.
  • Dahlin, Andreas P, et al. (author)
  • Refined microdialysis method for protein biomarker sampling in acute brain injury in the neurointensive care setting
  • 2014
  • In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 86:17, s. 8671-8679
  • Journal article (peer-reviewed)abstract
    • There is growing interest in cerebral microdialysis (MD) for sampling of protein biomarkers in neurointensive care (NIC) patients. Published data point to inherent problems with this methodology including protein interaction and biofouling leading to unstable catheter performance. This study tested the in vivo performance of a refined MD method including catheter surface modification, for protein biomarker sampling in a clinically relevant porcine brain injury model. Seven pigs of both sexes (10-12 weeks old; 22.2-27.3 kg) were included. Mean arterial blood pressure, heart rate, intracranial pressure (ICP) and cerebral perfusion pressure was recorded during the stepwise elevation of intracranial pressure by inflation of an epidural balloon catheter with saline (1 mL/20 min) until brain death. One naïve MD catheter and one surface modified with Pluronic F-127 (10 mm membrane, 100 kDa molecular weight cutoff MD catheter) were inserted into the right frontal cortex and perfused with mock CSF with 3% Dextran 500 at a flow rate of 1.0 μL/min and 20 min sample collection. Naïve catheters showed unstable fluid recovery, sensitive to ICP changes, which was significantly stabilized by surface modification. Three of seven naïve catheters failed to deliver a stable fluid recovery. MD levels of glucose, lactate, pyruvate, glutamate, glycerol and urea measured enzymatically showed an expected gradual ischemic and cellular distress response to the intervention without differences between naïve and surface modified catheters. The 17 most common proteins quantified by iTRAQ and nanoflow LC-MS/MS were used as biomarker models. These proteins showed a significantly more homogeneous response to the ICP intervention in surface modified compared to naïve MD catheters with improved extraction efficiency for most of the proteins. The refined MD method appears to improve the accuracy and precision of protein biomarker sampling in the NIC setting.
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40.
  • Dyhrfort, Philip, et al. (author)
  • A Dedicated 21-Plex Proximity Extension Assay Panel for High-Sensitivity Protein Biomarker Detection Using Microdialysis in Severe Traumatic Brain Injury : The Next Step in Precision Medicine?
  • 2023
  • In: NEUROTRAUMA REPORTS. - : Mary Ann Liebert. - 2689-288X. ; 4:1, s. 25-40
  • Journal article (peer-reviewed)abstract
    • Cerebral protein profiling in traumatic brain injury (TBI) is needed to better comprehend secondary injury pathways. Cerebral microdialysis (CMD), in combination with the proximity extension assay (PEA) technique, has great potential in this field. By using PEA, we have previously screened >500 proteins from CMD samples collected from TBI patients. In this study, we customized a PEA panel prototype of 21 selected candidate protein biomarkers, involved in inflammation (13), neuroplasticity/-repair (six), and axonal injury (two). The aim was to study their temporal dynamics and relation to age, structural injury, and clinical outcome. Ten patients with severe TBI and CMD monitoring, who were treated in the Neurointensive Care Unit, Uppsala University Hospital, Sweden, were included. Hourly CMD samples were collected for up to 7 days after trauma and analyzed with the 21-plex PEA panel. Seventeen of the 21 proteins from the CMD sample analyses showed significantly different mean levels between days. Early peaks (within 48 h) were noted with interleukin (IL)-1 beta, IL-6, IL-8, granulocyte colony-stimulating factor, transforming growth factor alpha, brevican, junctional adhesion molecule B, and neurocan. C-X-C motif chemokine ligand 10 peaked after 3 days. Late peaks (>5 days) were noted with interleukin-1 receptor antagonist (IL-1ra), monocyte chemoattractant protein (MCP)-2, MCP-3, urokinase-type plasminogen activator, Dickkopf-related protein 1, and DRAXIN. IL-8, neurofilament heavy chain, and TAU were biphasic. Age (above/below 22 years) interacted with the temporal dynamics of IL-6, IL-1ra, vascular endothelial growth factor, MCP-3, and TAU. There was no association between radiological injury (Marshall grade) or clinical outcome (Extended Glasgow Outcome Scale) with the protein expression pattern. The PEA method is a highly sensitive molecular tool for protein profiling from cerebral tissue in TBI. The novel TBI dedicated 21-plex panel showed marked regulation of proteins belonging to the inflammation, plasticity/repair, and axonal injury families. The method may enable important insights into complex injury processes on a molecular level that may be of value in future efforts to tailor pharmacological TBI trials to better address specific disease processes and optimize timing of treatments.
  •  
41.
  • Dyhrfort, Philip, et al. (author)
  • Monitoring of Protein Biomarkers of Inflammation in Human Traumatic Brain Injury Using Microdialysis and Proximity Extension Assay Technology in Neurointensive Care
  • 2019
  • In: Journal of Neurotrauma. - : MARY ANN LIEBERT, INC. - 0897-7151 .- 1557-9042. ; 36:20, s. 2872-2885
  • Journal article (peer-reviewed)abstract
    • Traumatic brain injury (TBI) is followed by secondary injury mechanisms strongly involving neuroinflammation. To monitor the complex inflammatory cascade in human TBI, we used cerebral microdialysis (MD) and multiplex proximity extension assay (PEA) technology and simultaneously measured levels of 92 protein biomarkers of inflammation in MD samples every three hours for five days in 10 patients with severe TBI under neurointensive care. One mu L MD samples were incubated with paired oligonucleotide-conjugated antibodies binding to each protein, allowing quantification by real-time quantitative polymerase chain reaction. Sixty-nine proteins were suitable for statistical analysis. We found five different patterns with either early (<48 h; e.g., CCL20, IL6, LIF, CCL3), mid (48-96 h; e.g., CCL19, CXCL5, CXCL10, MMP1), late (>96 h; e.g., CD40, MCP2, MCP3), biphasic peaks (e.g., CXCL1, CXCL5, IL8) or stable (e.g., CCL4, DNER, VEGFA)/low trends. High protein levels were observed for e.g., CXCL1, CXCL10, MCP1, MCP2, IL8, while e.g., CCL28 and MCP4 were detected at low levels. Several proteins (CCL8, -19, -20, -23, CXCL1, -5, -6, -9, -11, CST5, DNER, Flt3L, and SIRT2) have not been studied previously in human TBI. Cross-correlation analysis revealed that LIF and CXCL5 may play a central role in the inflammatory cascade. This study provides a unique data set with individual temporal trends for potential inflammatory biomarkers in patients with TBI. We conclude that the combination of MD and PEA is a powerful tool to map the complex inflammatory cascade in the injured human brain. The technique offers new possibilities of protein profiling of complex secondary injury pathways.
  •  
42.
  • Engquist, Henrik, et al. (author)
  • CBF changes and cerebral energy metabolism during hypervolemia, hemodilution, and hypertension therapy in patients with poor-grade subarachnoid hemorrhage
  • 2021
  • In: Journal of Neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 134:2, s. 555-564
  • Journal article (peer-reviewed)abstract
    • OBJECTIVE: Despite the multifactorial pathogenesis of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH), augmentation of cerebral blood flow (CBF) is still considered essential in the clinical management of DCI. The aim of this prospective observational study was to investigate cerebral metabolic changes in relation to CBF during therapeutic hypervolemia, hemodilution, and hypertension (HHH) therapy in poor-grade SAH patients with DCI.METHODS: CBF was assessed by bedside xenon-enhanced CT at days 0–3, 4–7, and 8–12, and the cerebral metabolic state by cerebral microdialysis (CMD), analyzing glucose, lactate, pyruvate, and glutamate hourly. At clinical suspicion of DCI, HHH therapy was instituted for 5 days. CBF measurements and CMD data at baseline and during HHH therapy were required for study inclusion. Non-DCI patients with measurements in corresponding time windows were included as a reference group.RESULTS: In DCI patients receiving HHH therapy (n = 12), global cortical CBF increased from 30.4 ml/100 g/min (IQR 25.1–33.8 ml/100 g/min) to 38.4 ml/100 g/min (IQR 34.2–46.1 ml/100 g/min; p = 0.006). The energy metabolic CMD parameters stayed statistically unchanged with a lactate/pyruvate (L/P) ratio of 26.9 (IQR 22.9–48.5) at baseline and 31.6 (IQR 22.4–35.7) during HHH. Categorized by energy metabolic patterns during HHH, no patient had severe ischemia, 8 showed derangement corresponding to mitochondrial dysfunction, and 4 were normal. The reference group of non-DCI patients (n = 11) had higher CBF and lower L/P ratios at baseline with no change over time, and the metabolic pattern was normal in all these patients.CONCLUSIONS: Global and regional CBF improved and the cerebral energy metabolic CMD parameters stayed statistically unchanged during HHH therapy in DCI patients. None of the patients developed metabolic signs of severe ischemia, but a disturbed energy metabolic pattern was a common occurrence, possibly explained by mitochondrial dysfunction despite improved microcirculation.
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43.
  • Engquist, Henrik, 1964- (author)
  • Clinical Bedside Studies of Cerebral Blood Flow in Severe Subarachnoid Hemorrhage Using Xenon CT
  • 2020
  • Doctoral thesis (other academic/artistic)abstract
    • Aneurysmal subarachnoid hemorrhage (SAH) is frequently complicated by delayed cerebral ischemia (DCI), contributing to poor outcome. Particularly for patients in poor neurological state, prediction of the acute clinical course is difficult, as is the early detection of DCI. Repeated measurement of global and regional cerebral blood flow (CBF) could potentially identify patients at risk of deterioration and guide in the clinical management.The studies in this thesis are based on bedside measurements of CBF by xenon-enhanced CT with the aim to assess and characterize global and regional CBF disturbances at different phases in the acute course after severe SAH. Furthermore, the effects of hemodynamic augmentation by hypervolemia, hemodilution and hypertension (HHH-therapy) on CBF and cerebral energy metabolism in patients with DCI are addressed.In Paper I, CBF disturbances at the early phase (day 0–3) after SAH were found common and often heterogeneous with substantial regions of near ischemic CBF. Older age and more severe hemorrhage (graded according to Fisher from CT) were factors associated with more compromised CBF. In Paper II, exploring the temporal dynamics of CBF, low initial CBF was associated with a persistent low level of CBF at day 4–7. The association was more pronounced when patients receiving HHH-therapy were separated, and indicates that patients with low CBF, even without clinical signs of DCI, could benefit from careful surveillance and optimization of circulation. In Paper III, the effects on CBF from HHH-therapy in patients with DCI was assessed. Hematocrit decreased during treatment, while the increase in systemic blood pressure was modest. Global CBF and CBF of the worst perfused regions increased, and the proportion of regions with critically low flow decreased accordingly. In Paper IV, the effects of HHH was further assessed in patients also monitored with cerebral microdialysis (CMD). CBF improved during HHH-therapy, while the cerebral energy metabolic CMD parameters stayed statistically unchanged. None of the patients developed metabolic signs of severe ischemia, but a disturbed energy metabolic pattern was common, possibly explained by mitochondrial dysfunction.
  •  
44.
  • Engquist, Henrik, et al. (author)
  • Effect of HHH-Therapy on Regional CBF after Severe Subarachnoid Hemorrhage Studied by Bedside Xenon-Enhanced CT
  • 2018
  • In: Neurocritical Care. - : Springer Science and Business Media LLC. - 1541-6933 .- 1556-0961. ; 28:2, s. 143-151
  • Journal article (peer-reviewed)abstract
    • BACKGROUND:Management of delayed cerebral ischemia (DCI) following subarachnoid hemorrhage (SAH) is difficult and still carries controversies. In this study, the effect of therapeutic hypervolemia, hemodilution, and hypertension (HHH-therapy) on cerebral blood flow (CBF) was assessed by xenon-enhanced computerized tomography (XeCT) hypothesizing an increase in CBF in poorly perfused regions.METHODS:Bedside XeCT measurements of regional CBF in mechanically ventilated SAH patients were routinely scheduled for day 0-3, 4-7, and 8-12. At clinical suspicion of DCI, patients received 5-day HHH-therapy. For inclusion, XeCT was required at 0-48 h before start of HHH (baseline) and during therapy. Data from corresponding time-windows were also collected for non-DCI patients.RESULTS:Twenty patients who later developed DCI were included, and twenty-eight patients without DCI were identified for comparison. During HHH, there was a slight nonsignificant increase in systolic blood pressure (SBP) and a significant reduction in hematocrit. Median global cortical CBF for the DCI group increased from 29.5 (IQR 24.6-33.9) to 38.4 (IQR 27.0-41.2) ml/100 g/min (P = 0.001). There was a concomitant increase in regional CBF of the worst vascular territories, and the proportion of area with blood flow below 20 ml/100 g/min was significantly reduced. Non-DCI patients showed higher CBF at baseline, and no significant change over time.CONCLUSIONS:HHH-therapy appeared to increase global and regional CBF in DCI patients. The increase in SBP was small, while the decrease in hematocrit was more pronounced, which may suggest that intravascular volume status and rheological effects are of importance. XeCT may be potentially helpful in managing poor-grade SAH patients.
  •  
45.
  • Engquist, Henrik, et al. (author)
  • Hemodynamic Disturbances in the Early Phase After Subarachnoid Hemorrhage : Regional Cerebral Blood Flow Studied by Bedside Xenon-enhanced CT.
  • 2018
  • In: Journal of Neurosurgical Anesthesiology. - 0898-4921 .- 1537-1921. ; 30:1, s. 49-58
  • Journal article (peer-reviewed)abstract
    • BACKGROUND: The mechanisms leading to neurological deterioration and the devastating course of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) are still not well understood. Bedside xenon-enhanced computerized tomography (XeCT) enables measurements of regional cerebral blood flow (rCBF) during neurosurgical intensive care. In the present study, CBF characteristics in the early phase after severe SAH were explored and related to clinical characteristics and early clinical course outcome.MATERIALS AND METHODS: Patients diagnosed with SAH and requiring mechanical ventilation were prospectively enrolled in the study. Bedside XeCT was performed within day 0 to 3.RESULTS: Data from 64 patients were obtained. Median global CBF was 34.9 mL/100 g/min (interquartile range [IQR], 26.7 to 41.6). There was a difference in CBF related to age with higher global CBF in the younger patients (30 to 49 y). CBF was also related to the severity of SAH with lower CBF in Fisher grade 4 compared with grade 3. rCBF disturbances and hypoperfusion were common; in 43 of the 64 patients rCBF<20 mL/100 g/min was detected in more than 10% of the region-of-interest (ROI) area and in 17 patients such low-flow area exceeded 30%. rCBF was not related to the localization of the aneurysm; there was no difference in rCBF of ipsilateral compared with contralateral vascular territories. In patients who initially were in Hunt & Hess grade I to III, median global CBF day 0 to 3 was significantly lower for patients who were in poor neurological state at discharge compared with patients in good neurological state, 25.5 mL/100 g/min (IQR, 21.3 to 28.3) versus 37.8 mL/100 g/min (IQR, 30.5 to 47.6).CONCLUSIONS: CBF disturbances are common in the early phase after SAH. In many patients, CBF was heterogenic and substantial areas with low rCBF were detected. Age and CT Fisher grade were factors influencing global cortical CBF. Bedside XeCT may be a tool to identify patients at risk of deteriorating so they can receive intensified management, but this needs further exploration.
  •  
46.
  • Fahlström, Markus, et al. (author)
  • A mathematical model for temporal cerebral blood flow response to acetazolamide evaluated in patients with Moyamoya disease
  • 2024
  • In: Magnetic Resonance Imaging. - : Elsevier. - 0730-725X .- 1873-5894. ; 110, s. 35-42
  • Journal article (peer-reviewed)abstract
    • Background: Paired cerebral blood flow (CBF) measurement is usually acquired before and after vasoactive stimulus to estimate cerebrovascular reserve (CVR). However, CVR may be confounded because of variations in time-to-maximum CBF response (tmax) following acetazolamide injection. With a mathematical model, CVR can be calculated insensitive to variations in tmax, and a model offers the possibility to calculate additional model-derived parameters. A model that describes the temporal CBF response following a vasodilating acetazolamide injection is proposed and evaluated.Methods: A bi-exponential model was adopted and fitted to four CBF measurements acquired using arterial spin labelling before and initialised at 5, 15 and 25 min after acetazolamide injection in a total of fifteen patients with Moyamoya disease. Curve fitting was performed using a non-linear least squares method with a priori constraints based on simulations.Results: Goodness of fit (mean absolute error) varied between 0.30 and 0.62 ml·100 g-1·min-1. Model-derived CVR was significantly higher compared to static CVR measures. Maximum CBF increase occurred earlier in healthy- compared to diseased vascular regions.Conclusions: The proposed mathematical model offers the possibility to calculate CVR insensitive to variations in time to maximum CBF response which gives a more detailed characterisation of CVR compared to static CVR measures. Although the mathematical model adapts generally well to this dataset of patients with MMD it should be considered as experimental; hence, further studies in healthy populations and other patient cohorts are warranted.
  •  
47.
  • Fahlström, Markus, et al. (author)
  • Evaluation of single-delay arterial spin labeling-based spatial coefficient of variation and histogram-based parameters in relation to cerebrovascular reserve in patients with Moyamoya disease.
  • 2023
  • In: Frontiers in Neurology. - : Frontiers Media S.A.. - 1664-2295. ; 14
  • Journal article (peer-reviewed)abstract
    • INTRODUCTION: Single-delay Arterial Spin Labeling (ASL)-based spatial coefficient of variation (CoVCBF) has been suggested as a measure of hemodynamic disturbance in patients with cerebrovascular diseases. However, spatial CoVCBF and other histogram-based parameters such as skewness and kurtosis and the volume of the arterial transit time artefact (ATAvol), has not been evaluated in patients with MMD nor against cerebrovascular reserve (CVR). The aim of this study was to assess whether any associations between spatial CoVCBF, skewness, kurtosis, and ATAvol are present and to analyze any potential associations with CVR, derived from single-delay ASL in patients with MMD.METHODS: Fifteen MMD patients were included before or after revascularization surgery. Cerebral blood flow (CBF) maps were acquired using pseudo-continuous ASL before, and 5, 15, and 25 min after an intravenous acetazolamide injection. CVRmax was defined as the highest percentual increase in CBF at any of the three post-injection time points. A vascular territory template was spatially normalized to each patient, including the bilateral anterior, middle, and posterior cerebral arteries. All affected anterior and middle cerebral artery regions and all unaffected posterior cerebral artery regions were included, based on Suzuki grading by digital subtraction angiography.RESULTS: Significant differences between affected and unaffected regions were found for CBF, CVRmax, and ATAvol. No association was found between CVRmax and any other parameter. High correlations were found between spatial CoVCBF, skewness and ATAvol.CONCLUSION: Spatial CoVCBF derived from single-delay ASL does not correlate with CVR in patients with MMD. Moreover, skewness and kurtosis did not provide additional information of clinical value.
  •  
48.
  • Fahlström, Markus, et al. (author)
  • High Intravascular Signal Arterial Transit Time Artifacts Have Negligible Effects on Cerebral Blood Flow and Cerebrovascular Reserve Capacity Measurement Using Single Postlabel Delay Arterial Spin-Labeling in Patients with Moyamoya Disease
  • 2020
  • In: American Journal of Neuroradiology. - 0195-6108 .- 1936-959X. ; 41:3, s. 430-436
  • Journal article (peer-reviewed)abstract
    • BACKGROUND AND PURPOSE: Arterial spin-labeling-derived CBF values may be affected by arterial transit time artefacts. Thus, our aim was to assess to what extent arterial spin-labeling–derived CBF and cerebrovascular reserve capacity values in major vascular regions are overestimated due to the arterial transit time artifacts in patients with Moyamoya disease.MATERIALS AND METHODS: Eight patients with Moyamoya disease were included before or after revascularization surgery. CBF maps were acquired using a 3D pseudocontinuous arterial spin-labeling sequence, before and 5, 15, and 25 minutes after an IV acetazolamide injection and were registered to each patient’s 3D-T1-weighted images. Vascular regions were defined by spatial normalization to a Montreal Neurological Institute–based vascular regional template. The arterial transit time artifacts were defined as voxels with high signal intensity corresponding to the right tail of the histogram for a given vascular region, with the cutoff selected by visual inspection. Arterial transit time artifact maps were created and applied as masks to exclude arterial transit time artifacts on CBF maps, to create corrected CBF maps. The cerebrovascular reserve capacity was calculated as CBF after acetazolamide injection relative to CBF at baseline for corrected and uncorrected CBF values, respectively.RESULTS: A total of 16 examinations were analyzed. Arterial transit time artifacts were present mostly in the MCA, whereas the posterior cerebral artery was generally unaffected. The largest differences between corrected and uncorrected CBF and cerebrovascular reserve capacity values, reported as patient group average ratio and percentage point difference, respectively, were 0.978 (95% CI, 0.968–0.988) and 1.8 percentage points (95% CI, 0.3–3.2 percentage points). Both were found in the left MCA, 15 and 5 minutes post-acetazolamide injection, respectively.CONCLUSIONS: Arterial transit time artifacts have negligible overestimation effects on calculated vascular region-based CBF and cerebrovascular reserve capacity values derived from single-delay 3D pseudocontinuous arterial spin-labeling.
  •  
49.
  • Fahlström, Markus, et al. (author)
  • Variable Temporal Cerebral Blood Flow Response to Acetazolamide in Moyamoya Patients Measured Using Arterial Spin Labeling
  • 2021
  • In: Frontiers in Neurology. - : Frontiers Media S.A.. - 1664-2295. ; 12
  • Journal article (peer-reviewed)abstract
    • Cerebrovascular reserve capacity (CVR), an important predictor of ischaemic events and a prognostic factor for patients with moyamoya disease (MMD), can be assessed by measuring cerebral blood flow (CBF) before and after administration of acetazolamide (ACZ). Often, a single CBF measurement is performed between 5 and 20 min after ACZ injection. Assessment of the temporal response of the vasodilation secondary to ACZ administration using several repeated CBF measurements has not been studied extensively. Furthermore, the high standard deviations of the group-averaged CVRs reported in the current literature indicate a patient-specific dispersion of CVR values over a wide range. This study aimed to assess the temporal response of the CBF and derived CVR during ACZ challenge using arterial spin labeling in patients with MMD. Eleven patients with MMD were included before or after revascularisation surgery. CBF maps were acquired using pseudo-continuous arterial spin labeling before and 5, 15, and 25 min after an intravenous ACZ injection. A vascular territory template was spatially normalized to patient-specific space, including the bilateral anterior, middle, and posterior cerebral arteries. CBF increased significantly post-ACZ injection in all vascular territories and at all time points. Group-averaged CBF and CVR values remained constant throughout the ACZ challenge in most patients. The maximum increase in CBF occurred most frequently at 5 min post-ACZ injection. However, peaks at 15 or 25 min were also present in some patients. In 68% of the affected vascular territories, the maximum increase in CBF did not occur at 15 min. In individual cases, the difference in CVR between different time points was between 1 and 30% points (mean difference 8% points). In conclusion, there is a substantial variation in CVR between different time points after the ACZ challenge in patients with MMD. Thus, there is a risk that the use of a single post-ACZ measurement time point overestimates disease progression, which could have wide implications for decision-making regarding revascularisation surgery and the interpretation of the outcome thereof. Further studies with larger sample sizes using multiple CBF measurements post-ACZ injection in patients with MMD are encouraged.
  •  
50.
  • Fischerström, Ann, et al. (author)
  • Acute neurosurgery for traumatic brain injury by general surgeons in Swedish county hospitals : A regional study
  • 2014
  • In: Acta Neurochirurgica. - : Springer Science and Business Media LLC. - 0001-6268 .- 0942-0940. ; 156:1, s. 177-185
  • Journal article (peer-reviewed)abstract
    • Traditionally acute life-saving evacuations of extracerebral haematomas are performed by general surgeons on vital indication in county hospitals in the Uppsala-A-rebro health care region in Sweden, a region characterized by long distances and a sparsely distributed population. Recently, it was stated in the guidelines for prehospital care of traumatic brain injury from the Scandinavian Neurosurgical Society that acute neurosurgery should not be performed in smaller hospitals without neurosurgical expertise. The aim of this study was to investigate: how often does acute decompressive neurosurgery occur in county hospitals in the Uppsala-A-rebro region today, what is the indication for surgery, and what is the clinical outcome? Finally, the goal was to evaluate whether the current practice in the Uppsala-A-rebro region should be revised. Patients referred to the neurointensive care unit at the Department of Neurosurgery in Uppsala after acute evacuation of intracranial haematomas in the county hospitals 2005-2010 were included in the study. Data was collected retrospectively from the medical records following a predefined protocol. The presence of vital indication, radiological and clinical results, and long-term outcome were evaluated. A total of 49 patients (17 epidural haematomas and 32 acute subdural haematomas) were included in the study. The operation was judged to have been performed on vital indication in all cases. The postoperative CT scan was improved in 92 % of the patients. The reaction level and pupillary reactions were significantly improved after surgery. Long-term outcomes showed 51 % favourable outcome, 33 % unfavourable outcome, and in 16 % the outcome was unknown. Looking at the indication for acute neurosurgery, the postoperative clinical and radiological results, and the long-term outcome, it appears that our regional policy regarding life-saving decompressive neurosurgery in county hospitals by general surgeons should not be changed. We suggest a curriculum aimed at educating general surgeons in acute neurosurgery.
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