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1.
Brain ; 145(4): 1264-1284, 2022 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-35411920

RESUMO

Focal brain damage after aneurysmal subarachnoid haemorrhage predominantly results from intracerebral haemorrhage, and early and delayed cerebral ischaemia. The prospective, observational, multicentre, cohort, diagnostic phase III trial, DISCHARGE-1, primarily investigated whether the peak total spreading depolarization-induced depression duration of a recording day during delayed neuromonitoring (delayed depression duration) indicates delayed ipsilateral infarction. Consecutive patients (n = 205) who required neurosurgery were enrolled in six university hospitals from September 2009 to April 2018. Subdural electrodes for electrocorticography were implanted. Participants were excluded on the basis of exclusion criteria, technical problems in data quality, missing neuroimages or patient withdrawal (n = 25). Evaluators were blinded to other measures. Longitudinal MRI, and CT studies if clinically indicated, revealed that 162/180 patients developed focal brain damage during the first 2 weeks. During 4.5 years of cumulative recording, 6777 spreading depolarizations occurred in 161/180 patients and 238 electrographic seizures in 14/180. Ten patients died early; 90/170 developed delayed infarction ipsilateral to the electrodes. Primary objective was to investigate whether a 60-min delayed depression duration cut-off in a 24-h window predicts delayed infarction with >0.60 sensitivity and >0.80 specificity, and to estimate a new cut-off. The 60-min cut-off was too short. Sensitivity was sufficient [= 0.76 (95% confidence interval: 0.65-0.84), P = 0.0014] but specificity was 0.59 (0.47-0.70), i.e. <0.80 (P < 0.0001). Nevertheless, the area under the receiver operating characteristic (AUROC) curve of delayed depression duration was 0.76 (0.69-0.83, P < 0.0001) for delayed infarction and 0.88 (0.81-0.94, P < 0.0001) for delayed ischaemia (reversible delayed neurological deficit or infarction). In secondary analysis, a new 180-min cut-off indicated delayed infarction with a targeted 0.62 sensitivity and 0.83 specificity. In awake patients, the AUROC curve of delayed depression duration was 0.84 (0.70-0.97, P = 0.001) and the prespecified 60-min cut-off showed 0.71 sensitivity and 0.82 specificity for reversible neurological deficits. In multivariate analysis, delayed depression duration (ß = 0.474, P < 0.001), delayed median Glasgow Coma Score (ß = -0.201, P = 0.005) and peak transcranial Doppler (ß = 0.169, P = 0.016) explained 35% of variance in delayed infarction. Another key finding was that spreading depolarization-variables were included in every multiple regression model of early, delayed and total brain damage, patient outcome and death, strongly suggesting that they are an independent biomarker of progressive brain injury. While the 60-min cut-off of cumulative depression in a 24-h window indicated reversible delayed neurological deficit, only a 180-min cut-off indicated new infarction with >0.60 sensitivity and >0.80 specificity. Although spontaneous resolution of the neurological deficit is still possible, we recommend initiating rescue treatment at the 60-min rather than the 180-min cut-off if progression of injury to infarction is to be prevented.


Assuntos
Lesões Encefálicas , Depressão Alastrante da Atividade Elétrica Cortical , Hemorragia Subaracnóidea , Lesões Encefálicas/complicações , Infarto Cerebral/complicações , Eletrocorticografia , Humanos , Estudos Prospectivos , Hemorragia Subaracnóidea/complicações , Hemorragia Subaracnóidea/diagnóstico por imagem
2.
BMC Neurol ; 21(1): 363, 2021 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-34537017

RESUMO

BACKGROUND: When MRI fails to detect a potentially epileptogenic lesion, the chance of a favorable outcome after epilepsy surgery becomes significantly lower (from 60 to 90% to 20-65%). Hybrid FDG-PET/MRI may provide additional information for identifying the epileptogenic zone. We aimed to investigate the possible effect of the introduction of hybrid FDG-PET/MRI into the algorithm of the decision-making in both lesional and non-lesional drug-resistant epileptic patients. METHODS: In a prospective study of patients suffering from drug-resistant focal epilepsy, 30 nonlesional and 30 lesional cases with discordant presurgical results were evaluated using hybrid FDG-PET/MRI. RESULTS: The hybrid imaging revealed morphological lesion in 18 patients and glucose hypometabolism in 29 patients within the nonlesional group. In the MRI positive group, 4 patients were found to be nonlesional, and in 9 patients at least one more epileptogenic lesion was discovered, while in another 17 cases the original lesion was confirmed by means of hybrid FDG-PET/MRI. As to the therapeutic decision-making, these results helped to indicate resective surgery instead of intracranial EEG (iEEG) monitoring in 2 cases, to avoid any further invasive diagnostic procedures in 7 patients, and to refer 21 patients for iEEG in the nonlesional group. Hybrid FDG-PET/MRI has also significantly changed the original therapeutic plans in the lesional group. Prior to the hybrid imaging, a resective surgery was considered in 3 patients, and iEEG was planned in 27 patients. However, 3 patients became eligible for resective surgery, 6 patients proved to be inoperable instead of iEEG, and 18 cases remained candidates for iEEG due to the hybrid FDG-PET/MRI. Two patients remained candidates for resective surgery and one patient became not eligible for any further invasive intervention. CONCLUSIONS: The results of hybrid FDG-PET/MRI significantly altered the original plans in 19 of 60 cases. The introduction of hybrid FDG-PET/MRI into the presurgical evaluation process had a potential modifying effect on clinical decision-making. TRIAL REGISTRATION: Trial registry: Scientific Research Ethics Committee of the Medical Research Council of Hungary. TRIAL REGISTRATION NUMBER: 008899/2016/OTIG . Date of registration: 08 February 2016.


Assuntos
Epilepsia , Preparações Farmacêuticas , Eletroencefalografia , Fluordesoxiglucose F18 , Humanos , Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons , Estudos Prospectivos
3.
Brain ; 141(6): 1734-1752, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29668855

RESUMO

Spreading depolarizations are characterized by abrupt, near-complete breakdown of the transmembrane ion gradients, neuronal oedema, mitochondrial depolarization, glutamate excitotoxicity and activity loss (depression). Spreading depolarization induces either transient hyperperfusion in normal tissue; or hypoperfusion (inverse coupling = spreading ischaemia) in tissue at risk for progressive injury. The concept of the spreading depolarization continuum is critical since many spreading depolarizations have intermediate characteristics, as opposed to the two extremes of spreading depolarization in either severely ischaemic or normal tissue. In animals, the spreading depolarization extreme in ischaemic tissue is characterized by prolonged depolarization durations, in addition to a slow baseline variation termed the negative ultraslow potential. The negative ultraslow potential is initiated by spreading depolarization and similar to the negative direct current (DC) shift of prolonged spreading depolarization, but specifically refers to a negative potential component during progressive recruitment of neurons into cell death in the wake of spreading depolarization. We here first quantified the spreading depolarization-initiated negative ultraslow potential in the electrocorticographic DC range and the activity depression in the alternate current range after middle cerebral artery occlusion in rats. Relevance of these variables to the injury was supported by significant correlations with the cortical infarct volume and neurological outcome after 72 h of survival. We then identified negative ultraslow potential-containing clusters of spreading depolarizations in 11 patients with aneurysmal subarachnoid haemorrhage. The human platinum/iridium-recorded negative ultraslow potential showed a tent-like shape. Its amplitude of 45.0 (39.0, 69.4) mV [median (first, third quartile)] was 6.6 times larger and its duration of 3.7 (3.3, 5.3) h was 34.9 times longer than the negative DC shift of spreading depolarizations in less compromised tissue. Using Generalized Estimating Equations applied to a logistic regression model, we found that negative ultraslow potential displaying electrodes were significantly more likely to overlie a developing ischaemic lesion (90.0%, 27/30) than those not displaying a negative ultraslow potential (0.0%, 0/20) (P = 0.004). Based on serial neuroimages, the lesions under the electrodes developed within a time window of 72 (56, 134) h. The negative ultraslow potential occurred in this time window in 9/10 patients. It was often preceded by a spreading depolarization cluster with increasingly persistent spreading depressions and progressively prolonged DC shifts and spreading ischaemias. During the negative ultraslow potential, spreading ischaemia lasted for 40.0 (28.0, 76.5) min, cerebral blood flow fell from 57 (53, 65) % to 26 (16, 42) % (n = 4) and tissue partial pressure of oxygen from 12.5 (9.2, 15.2) to 3.3 (2.4, 7.4) mmHg (n = 5). Our data suggest that the negative ultraslow potential is the electrophysiological correlate of infarction in human cerebral cortex and a neuromonitoring-detected medical emergency.awy102media15775596049001.


Assuntos
Infarto Encefálico/patologia , Infarto Encefálico/fisiopatologia , Córtex Cerebral/fisiopatologia , Depressão Alastrante da Atividade Elétrica Cortical/fisiologia , Infarto da Artéria Cerebral Média/patologia , Adulto , Animais , Infarto Encefálico/diagnóstico por imagem , Mapeamento Encefálico , Córtex Cerebral/diagnóstico por imagem , Modelos Animais de Doenças , Eletrocorticografia , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Infarto da Artéria Cerebral Média/complicações , Infarto da Artéria Cerebral Média/fisiopatologia , Modelos Lineares , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Neurônios/patologia , Ratos , Ratos Sprague-Dawley , Fatores de Tempo
4.
Neuroscience ; 509: 132-144, 2023 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-36460221

RESUMO

Spreading depolarizations (SD) refer to the near-complete depolarization of neurons that is associated with brain injuries such as ischemic stroke. The present gold standard for SD monitoring in humans is invasive electrocorticography (ECoG). A promising non-invasive alternative to ECoG is diffuse optical monitoring of SD-related flow and hemoglobin transients. To investigate the clinical utility of flow and hemoglobin transients, we analyzed their association with infarction in rat focal brain ischemia. Optical images of flow, oxy-hemoglobin, and deoxy-hemoglobin were continuously acquired with Laser Speckle and Optical Intrinsic Signal imaging for 2 h after photochemically induced distal middle cerebral artery occlusion in Sprague-Dawley rats (n = 10). Imaging was performed through a 6 × 6 mm window centered 3 mm posterior and 4 mm lateral to Bregma. Rats were sacrificed after 24 h, and the brain slices were stained for assessment of infarction. We mapped the infarcted area onto the imaging data and used nine circular regions of interest (ROI) to distinguish infarcted from non-infarcted tissue. Transients propagating through each ROI were characterized with six parameters (negative, positive, and total amplitude; negative and positive slope; duration). Transients were also classified into three morphology types (positive monophasic, biphasic, negative monophasic). Flow transient morphology, positive amplitude, positive slope, and total amplitude were all strongly associated with infarction (p < 0.001). Associations with infarction were also observed for oxy-hemoglobin morphology, oxy-hemoglobin positive amplitude and slope, and deoxy-hemoglobin positive slope and duration (all p < 0.01). These results suggest that flow and hemoglobin transients accompanying SD have value for detecting infarction.


Assuntos
Isquemia Encefálica , Depressão Alastrante da Atividade Elétrica Cortical , Oxiemoglobinas , Animais , Humanos , Ratos , Isquemia Encefálica/complicações , Circulação Cerebrovascular/fisiologia , Depressão Alastrante da Atividade Elétrica Cortical/fisiologia , Infarto da Artéria Cerebral Média , Ratos Sprague-Dawley
5.
Front Cell Neurosci ; 16: 837650, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35237133

RESUMO

Neuronal cytotoxic edema is the morphological correlate of the near-complete neuronal battery breakdown called spreading depolarization, or conversely, spreading depolarization is the electrophysiological correlate of the initial, still reversible phase of neuronal cytotoxic edema. Cytotoxic edema and spreading depolarization are thus different modalities of the same process, which represents a metastable universal reference state in the gray matter of the brain close to Gibbs-Donnan equilibrium. Different but merging sections of the spreading-depolarization continuum from short duration waves to intermediate duration waves to terminal waves occur in a plethora of clinical conditions, including migraine aura, ischemic stroke, traumatic brain injury, aneurysmal subarachnoid hemorrhage (aSAH) and delayed cerebral ischemia (DCI), spontaneous intracerebral hemorrhage, subdural hematoma, development of brain death, and the dying process during cardio circulatory arrest. Thus, spreading depolarization represents a prime and simultaneously the most neglected pathophysiological process in acute neurology. Aristides Leão postulated as early as the 1940s that the pathophysiological process in neurons underlying migraine aura is of the same nature as the pathophysiological process in neurons that occurs in response to cerebral circulatory arrest, because he assumed that spreading depolarization occurs in both conditions. With this in mind, it is not surprising that patients with migraine with aura have about a twofold increased risk of stroke, as some spreading depolarizations leading to the patient percept of migraine aura could be caused by cerebral ischemia. However, it is in the nature of spreading depolarization that it can have different etiologies and not all spreading depolarizations arise because of ischemia. Spreading depolarization is observed as a negative direct current (DC) shift and associated with different changes in spontaneous brain activity in the alternating current (AC) band of the electrocorticogram. These are non-spreading depression and spreading activity depression and epileptiform activity. The same spreading depolarization wave may be associated with different activity changes in adjacent brain regions. Here, we review the basal mechanism underlying spreading depolarization and the associated activity changes. Using original recordings in animals and patients, we illustrate that the associated changes in spontaneous activity are by no means trivial, but pose unsolved mechanistic puzzles and require proper scientific analysis.

6.
Biomedicines ; 10(5)2022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35625684

RESUMO

The aim of our prospective study was to evaluate the clinical impact of hybrid [18F]-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging ([18F]-FDG PET/MRI) on the decision workflow of epileptic patients with discordant electroclinical and MRI data. A novel mathematical model was introduced for a clinical concordance calculation supporting the classification of our patients by subgroups of clinical decisions. Fifty-nine epileptic patients with discordant clinical and diagnostic results or MRI negativity were included in this study. The diagnostic value of the PET/MRI was compared to other modalities of presurgical evaluation (e.g., electroclinical data, PET, and MRI). The results of the population-level statistical analysis of the introduced data fusion technique and concordance analysis demonstrated that this model could be the basis for the development of a more accurate clinical decision support parameter in the future. Therefore, making the establishment of "invasive" (operable and implantable) and "not eligible for any further invasive procedures" groups could be much more exact. Our results confirmed the relevance of PET/MRI with the diagnostic algorithm of presurgical evaluation. The introduction of a concordance analysis could be of high importance in clinical and surgical decision-making in the management of epileptic patients. Our study corroborated previous findings regarding the advantages of hybrid PET/MRI technology over MRI and electroclinical data.

7.
Clin Neurophysiol ; 132(8): 1982-1989, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34034963

RESUMO

OBJECTIVE: While many studies suggest that patients with Alzheimer's disease have a higher chance for developing epileptic seizures, only a few studies are available examining independent epileptic discharges. The major aims of our study was to determine the prevalence of subclinical epileptiform activity (SEA) in AD compared to healthy elderly controls with the hypothesis that SEA is more frequent in AD than in cognitively normal individuals. Another aim was to analyze the effect of baseline SEA captured with electroencephalography on the progression of the disease with longitudinal cognitive testing. METHODS: We investigated 52 Alzheimer patients with no history of epileptic seizures and 20 healthy individuals. All participants underwent a 24-hour electroencephalography, neurology, neuroimaging and neuropsychology examination. Two independent raters analyzed visually the electroencephalograms and both raters were blind to the diagnoses. Thirty-eight Alzheimer patients were enrolled in a 3-year long prospective follow-up study with yearly repeated cognitive evaluation. RESULTS: Subclinical epileptiform discharges were recorded significantly (p:0.018) more frequently in Alzheimer patients (54%) than in healthy elderly (25%). Epileptiform discharges were associated with lower performance scores in memory. Alzheimer patients with spikes showed 1.5-times faster decline in global cognitive scores than patients without (p < 0.001). The decline in cognitive performance scores showed a significant positive correlation with spike frequency (r:+0.664; p < 0.001). CONCLUSIONS: Subclinical epileptiform activity occurs in half of Alzheimer patients who have never suffered epileptic seizures. Alzheimer patients with subclinical epileptiform activity showed accelerated cognitive decline with a strong relation to the frequency and spatial distribution (left temporal) of spikes. SIGNIFICANCE: Our findings suggest the prominent role of epileptiform discharges in the pathomechanism of Alzheimer's disease which might serve as potential therapeutic target.


Assuntos
Doença de Alzheimer/diagnóstico , Doença de Alzheimer/fisiopatologia , Progressão da Doença , Eletroencefalografia/métodos , Convulsões/diagnóstico , Convulsões/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/psicologia , Feminino , Seguimentos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Estudos Prospectivos , Convulsões/psicologia , Fatores de Tempo
8.
Acta Neurochir (Wien) ; 152(1): 1-17, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19652904

RESUMO

PURPOSE: This review summarizes protein biomarkers in mild and severe traumatic brain injury in adults and children and presents a strategy for conducting rationally designed clinical studies on biomarkers in head trauma. METHODS: We performed an electronic search of the National Library of Medicine's MEDLINE and Biomedical Library of University of Pennsylvania database in March 2008 using a search heading of traumatic head injury and protein biomarkers. The search was focused especially on protein degradation products (spectrin breakdown product, c-tau, amyloid-beta(1-42)) in the last 10 years, but recent data on "classical" markers (S-100B, neuron-specific enolase, etc.) were also examined. RESULTS: We identified 85 articles focusing on clinical use of biomarkers; 58 articles were prospective cohort studies with injury and/or outcome assessment. CONCLUSIONS: We conclude that only S-100B in severe traumatic brain injury has consistently demonstrated the ability to predict injury and outcome in adults. The number of studies with protein degradation products is insufficient especially in the pediatric care. Cohort studies with well-defined end points and further neuroproteomic search for biomarkers in mild injury should be triggered. After critically reviewing the study designs, we found that large homogenous patient populations, consistent injury, and outcome measures prospectively determined cutoff values, and a combined use of different predictors should be considered in future studies.


Assuntos
Lesões Encefálicas/sangue , Proteínas/metabolismo , Peptídeos beta-Amiloides/sangue , Animais , Apolipoproteínas E/sangue , Biomarcadores/sangue , Lesões Encefálicas/fisiopatologia , Criança , Traumatismos Craniocerebrais/sangue , Proteína Glial Fibrilar Ácida/sangue , Humanos , Traumatismo Múltiplo/sangue , Fatores de Crescimento Neural/sangue , Fragmentos de Peptídeos/sangue , Fosfopiruvato Hidratase/sangue , Valor Preditivo dos Testes , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/sangue , Índice de Gravidade de Doença , Espectrina/metabolismo , Adulto Jovem , Proteínas tau/sangue , Proteínas tau/química
9.
Int J Mol Sci ; 11(4): 1253-68, 2010 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-20480019

RESUMO

We examined the neuro/axono-protective potential of a novel poly (ADP-ribose) polymerase (PARP) inhibitor L-2286 in a rat impact acceleration brain injury model. Male Wistar rats (n = 70) weighing 300-350 grams were used to determine the most effective intracerebroventricular (i.c.v.) dose of L-2286 administered 30 min after injury, and to test the neuroprotective effect at two time points (immediately, and 30 min after injury). The neuroprotective effect of L-2286 was tested using immunohistochemical (amyloid precursor protein and mid-sized mouse anti-neurofilament clone RMO-14.9 antibody) and behavioral tests (beam-balance, open-field and elevated plus maze). At both time-points, a 100 microg/rat dose of i.c.v. L-2286 significantly (p < 0.05) reduced the density of damaged axons in the corticospinal tract and medial longitudinal fascicle compared to controls. In the behavioral tests, treatment 30 min post-injury improved motor function, while the level of anxiety was reduced in both treatment protocols.


Assuntos
Comportamento Animal/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Fármacos Neuroprotetores/farmacologia , Piperidinas/farmacologia , Inibidores de Poli(ADP-Ribose) Polimerases , Quinazolinas/farmacologia , Animais , Ansiedade/patologia , Axônios/metabolismo , Axônios/patologia , Lesões Encefálicas/metabolismo , Lesões Encefálicas/patologia , Modelos Animais de Doenças , Inibidores Enzimáticos/química , Imuno-Histoquímica , Infusões Intraventriculares , Masculino , Fármacos Neuroprotetores/química , Piperidinas/química , Poli(ADP-Ribose) Polimerases/metabolismo , Quinazolinas/química , Ratos , Ratos Wistar
10.
J Neurosci Res ; 87(5): 1219-29, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19006084

RESUMO

Little information exists on the role and the characteristics of perfusion changes related to periinfarct depolarization. Our aim was to visualize and monitor periinfarct flow transients (PIFTs) in Sprague-Dawley rats (n = 10) with two different laser methods in a closed-skull model of filament middle cerebral artery occlusion. A laser Doppler probe was placed over the ischemic cortex 5 mm lateral to Bregma, and a 5 x 5 mm area centered 5 mm posterior and 4 mm lateral to Bregma was thinned for laser speckle imaging. Both neurological and histological evaluations were performed at 72 hr postinjury. Mean flow during 90-min ischemia was 29% of baseline measured by laser Doppler and 36-54% by laser speckle. Flow transients occurred in all rats, the number of PIFTs being 4.6 +/- 1.8/90 min. By both methods, 95.6% of them occurred with temporal correlation. The average duration of PIFTs was also identical (162 +/- 24 and 162 +/- 34 sec, respectively). Five different morphologies of flow transients ranging from hypoperfusive to hyperemic were identified by laser speckle. The PIFTs changed their morphology dynamically over certain regions. All of the animals showed an infarct (178.5 +/- 26 mm(3)) in the middle cerebral artery territory. Laser Doppler in itself can be a reliable method for counting/detecting PIFTs, but laser speckle is capable of monitoring the dynamic changes in PIFT morphology over the penumbral and periischemic cortex.


Assuntos
Encéfalo/irrigação sanguínea , Circulação Cerebrovascular , Infarto da Artéria Cerebral Média/fisiopatologia , Animais , Encéfalo/patologia , Encéfalo/fisiopatologia , Infarto da Artéria Cerebral Média/patologia , Fluxometria por Laser-Doppler , Masculino , Microcirculação , Ratos , Ratos Sprague-Dawley , Reologia
11.
J Neurotrauma ; 25(3): 205-13, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18352834

RESUMO

Although it is well known that traumatic brain injury (TBI) evokes traumatic axonal injury (TAI) within the brain, TBI-induced axonal damage in the spinal cord (SC) has been less extensively investigated. Detection of such axonal injury in the spinal cord would further the complexity of TBI while also challenging some functional neurobehavioral endpoints frequently used to assess recovery in various models of TBI. To assess TAI in the spinal cord associated with TBI, we analyzed the craniocervical junction (CCJ), cervico-thoracic (CT), and thoraco-lumber (ThL) spinal cord in a rodent model of impact acceleration of TBI of varying severities. Rats were transcardially fixed with aldehydes at 2, 6, and 24 h post-injury (n = 36); each group included on sham-injured rodent. Semi-serial vibratome sections were reacted with antibodies targeting TAI via alteration in cytoskeletal integrity or impaired axonal transport. Consistent with previous observations in this model, the CCJ contained numerous injured axons. Immunoreactive, damaged axonal profiles were also detected as caudal, as the ThL spinal cord displayed morphological characteristics entirely consistent with those described in the brainstem and the CCJ. Quantitative analyses demonstrated that the occurrence and extent of TAI is positively associated with the impact/energy of injury and negatively with the distance from the brainstem. These observations show that TBI can evoke TAI in regions remote from the injury site, including the spinal cord itself. This finding is relevant to shaken baby syndrome as well as during the analysis of data in functional recovery in various models of TBI.


Assuntos
Axônios/patologia , Lesões Encefálicas/fisiopatologia , Traumatismos da Medula Espinal/patologia , Traumatismos da Medula Espinal/fisiopatologia , Degeneração Walleriana/patologia , Degeneração Walleriana/fisiopatologia , Peptídeos beta-Amiloides/análise , Peptídeos beta-Amiloides/metabolismo , Animais , Biomarcadores/análise , Lesões Encefálicas/complicações , Tronco Encefálico/lesões , Tronco Encefálico/patologia , Tronco Encefálico/fisiopatologia , Proteínas do Citoesqueleto/análise , Proteínas do Citoesqueleto/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Imuno-Histoquímica , Proteínas do Tecido Nervoso/análise , Proteínas do Tecido Nervoso/metabolismo , Ratos , Ratos Wistar , Traumatismos da Medula Espinal/etiologia , Fatores de Tempo , Degeneração Walleriana/etiologia
12.
Brain Res ; 1191: 157-67, 2008 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-18096143

RESUMO

alpha-Chloralose is widely used as an anesthetic in studies of the cerebrovasculature because it provides robust metabolic and hemodynamic responses to functional stimulation. However, there have been no controlled studies of focal ischemia in the rat under alpha-chloralose anesthesia. Artificially ventilated rats were prepared using 1.2-1.5% isoflurane anesthesia for filament occlusion of the right middle cerebral artery (MCA), and anesthesia was either switched to alpha-chloralose (60 mg/kg bolus, 30 mg/kg/h; n=10) or was maintained on 1% isoflurane (n=10). Following temporary MCA occlusion EEG was monitored from a screw electrode and changes in cerebral blood flow (rCBF) measured with a laser Doppler probe placed over the ischemic cortex. This study shows that alpha-chloralose is a safe anesthetic for ischemia studies and provides excellent survival. Compared with isoflurane, the cortical and total infarct volumes are larger in the alpha-chloralose-anesthetized animals, while the functional outcome at 72 h is similar. The total duration of peri-infarct flow transients (PIFTs) is also significantly longer in alpha-chloralose-anesthetized animals. The average amplitude of the flow transients showed a good correlation with the extent of edema in all animals as did the total duration of non-convulsive seizures (NCS) in the alpha-chloralose-anesthetized animals.


Assuntos
Anestesia/métodos , Anestésicos Intravenosos/farmacologia , Isquemia Encefálica , Circulação Cerebrovascular/efeitos dos fármacos , Cloralose/farmacologia , Eletroencefalografia/efeitos dos fármacos , Anestesia/veterinária , Animais , Encéfalo/irrigação sanguínea , Encéfalo/efeitos dos fármacos , Lesões Encefálicas/fisiopatologia , Isquemia Encefálica/fisiopatologia , Modelos Animais de Doenças , Infarto da Artéria Cerebral Média , Isoflurano/farmacologia , Fluxometria por Laser-Doppler/veterinária , Masculino , Ratos , Ratos Sprague-Dawley
13.
Neuroimage Clin ; 16: 524-538, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28948141

RESUMO

In many cerebral grey matter structures including the neocortex, spreading depolarization (SD) is the principal mechanism of the near-complete breakdown of the transcellular ion gradients with abrupt water influx into neurons. Accordingly, SDs are abundantly recorded in patients with traumatic brain injury, spontaneous intracerebral hemorrhage, aneurysmal subarachnoid hemorrhage (aSAH) and malignant hemispheric stroke using subdural electrode strips. SD is observed as a large slow potential change, spreading in the cortex at velocities between 2 and 9 mm/min. Velocity and SD susceptibility typically correlate positively in various animal models. In patients monitored in neurocritical care, the Co-Operative Studies on Brain Injury Depolarizations (COSBID) recommends several variables to quantify SD occurrence and susceptibility, although accurate measures of SD velocity have not been possible. Therefore, we developed an algorithm to estimate SD velocities based on reconstructing SD trajectories of the wave-front's curvature center from magnetic resonance imaging scans and time-of-SD-arrival-differences between subdural electrode pairs. We then correlated variables indicating SD susceptibility with algorithm-estimated SD velocities in twelve aSAH patients. Highly significant correlations supported the algorithm's validity. The trajectory search failed significantly more often for SDs recorded directly over emerging focal brain lesions suggesting in humans similar to animals that the complexity of SD propagation paths increase in tissue undergoing injury.


Assuntos
Algoritmos , Córtex Cerebral/fisiopatologia , Depressão Alastrante da Atividade Elétrica Cortical/fisiologia , Interpretação de Imagem Assistida por Computador/métodos , Hemorragia Subaracnóidea/fisiopatologia , Adulto , Idoso , Eletrocorticografia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade
14.
J Cereb Blood Flow Metab ; 37(5): 1595-1625, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-27317657

RESUMO

Spreading depolarizations (SD) are waves of abrupt, near-complete breakdown of neuronal transmembrane ion gradients, are the largest possible pathophysiologic disruption of viable cerebral gray matter, and are a crucial mechanism of lesion development. Spreading depolarizations are increasingly recorded during multimodal neuromonitoring in neurocritical care as a causal biomarker providing a diagnostic summary measure of metabolic failure and excitotoxic injury. Focal ischemia causes spreading depolarization within minutes. Further spreading depolarizations arise for hours to days due to energy supply-demand mismatch in viable tissue. Spreading depolarizations exacerbate neuronal injury through prolonged ionic breakdown and spreading depolarization-related hypoperfusion (spreading ischemia). Local duration of the depolarization indicates local tissue energy status and risk of injury. Regional electrocorticographic monitoring affords even remote detection of injury because spreading depolarizations propagate widely from ischemic or metabolically stressed zones; characteristic patterns, including temporal clusters of spreading depolarizations and persistent depression of spontaneous cortical activity, can be recognized and quantified. Here, we describe the experimental basis for interpreting these patterns and illustrate their translation to human disease. We further provide consensus recommendations for electrocorticographic methods to record, classify, and score spreading depolarizations and associated spreading depressions. These methods offer distinct advantages over other neuromonitoring modalities and allow for future refinement through less invasive and more automated approaches.


Assuntos
Lesões Encefálicas/fisiopatologia , Depressão Alastrante da Atividade Elétrica Cortical/fisiologia , Cuidados Críticos/métodos , Substância Cinzenta/fisiopatologia , Monitorização Neurofisiológica/métodos , Acidente Vascular Cerebral/fisiopatologia , Lesões Encefálicas/diagnóstico , Lesões Encefálicas/terapia , Circulação Cerebrovascular , Eletrocorticografia , Humanos , Guias de Prática Clínica como Assunto , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/terapia
15.
Artigo em Inglês | MEDLINE | ID: mdl-20725601

RESUMO

Our group has already published the possible neuroprotective effect of contralateral forepaw stimulation in temporary focal ischemia in a study. However, the background is still unclear. In the present study we investigated the possible mechanism by monitoring focal ischemia with multispectral [laser speckle, imaging of intrinsic signals (OIS)] imaging. Sprague-Dawley rats were prepared using 1.2% isoflurane anesthesia. The middle cerebral artery was occluded by photothrombosis (4 mW) and the common carotid artery was ligated permanently. Physiological variables were constantly monitored during the experiment. A 6 x 6 mm area centered 3 mm posterior and 4 mm lateral to Bregma was thinned for laser speckle and OIS imaging. Nine circular regions of interests (0.3 mm in diameter) were evenly spaced on the speckle contrast image for the analysis of peri-infarct flow transients, blood flow, and metabolic changes. Both the sham (n = 7) and forepaw-stimulated animals (n = 7) underwent neurological examinations 24 h after ischemia at which point all animals were sacrificed and the infarct size was determined by triphenyltetrazolium chloride. The physiological variables were in normal range and the experimental protocol did not cause significant differences between groups. Both the neurological scores (sham: 3.6 +/- 1.7, stimulated: 4.3 +/- 1.4) and the infarct volume (sham: 124 +/- 39 mm(3), stimulated: 147 +/- 47 mm(3)) did not show significant differences between groups. The forepaw stimulation did not increase the intra-ischemic flow neither over the penumbral or the peri-ischemic area. However, the hemoglobin transients related metabolic load (CMRO(2)) was significantly lower (p < 0.001) while the averaged number of hyperemic flow transients were significantly (p = 0.013) higher in the forepaw (sham: 3.5 +/- 2.2, stimulated: 7.0 +/- 2.3) stimulated animals.

16.
J Cereb Blood Flow Metab ; 30(8): 1504-19, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20332797

RESUMO

In human cortex it has been suggested that the tissue at risk is indicated by clusters of spreading depolarizations (SDs) with persistent depression of high-frequency electrocorticographic (ECoG) activity. We here characterized this zone in the ET-1 model in rats using direct current (DC)-ECoG recordings. Topical application of the vasoconstrictor endothelin-1 (ET-1) induces focal ischemia in a concentration-dependent manner restricted to a region exposed by a cranial window, while a healthy cortex can be studied at a second naïve window. SDs originate in the ET-1-exposed cortex and invade the surrounding tissue. Necrosis is restricted to the ET-1-exposed cortex. In this study, we discovered that persistent depression occurred in both ET-1-exposed and surrounding cortex during SD clusters. However, the ET-1-exposed cortex showed longer-lasting negative DC shifts and limited high-frequency ECoG recovery after the cluster. DC-ECoG recordings of SD clusters with persistent depression from patients with aneurysmal subarachnoid hemorrhage were then analyzed for comparison. Limited ECoG recovery was associated with significantly longer-lasting negative DC shifts in a similar manner to the experimental model. These preliminary results suggest that the ischemic zone in rat and human cortex is surrounded by a normally perfused belt with persistently reduced synaptic activity during the acute injury phase.


Assuntos
Isquemia Encefálica/fisiopatologia , Córtex Cerebral/fisiopatologia , Depressão Alastrante da Atividade Elétrica Cortical , Eletroencefalografia/métodos , Endotelina-1/metabolismo , Hemorragia Subaracnóidea/fisiopatologia , Animais , Humanos , Masculino , Ratos , Ratos Wistar
17.
J Cereb Blood Flow Metab ; 28(7): 1275-84, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18382471

RESUMO

After complete cerebral ischemia, the postischemic blood flow response to functional activation is severely attenuated for several hours. However, little is known about the spatial and temporal extent of the blood flow response in the acute postischemic period after incomplete cerebral ischemia. To investigate the relative cerebral blood flow (rCBF) response in the somatosensory cortex of rat to controlled vibrissae stimulation after transient incomplete ischemia (15-min bilateral common carotid artery occlusion+hypotension), we employed laser speckle imaging combined with statistical parametric mapping. We found that the ischemic insult had a significant impact on the baseline blood flow (P<0.005) and the activation area in response to functional stimulation was significantly reduced after ischemia (P<0.005). The maximum rCBF response in the activation area determined from the statistical analysis did not change significantly up to 3 h after ischemia (P>0.1). However, the time when rCBF response reached its maximum was significantly delayed (P<0.0001) from 2.4+/-0.2 secs before ischemia to 3.6+/-0.1 secs at 20 mins into reperfusion (P<0.001); the delay was reduced gradually to 2.9+/-0.2 secs after 3 h, which was still significantly greater than that observed before the insult (P=0.04).


Assuntos
Isquemia Encefálica/fisiopatologia , Córtex Cerebral/fisiopatologia , Circulação Cerebrovascular , Recuperação de Função Fisiológica/fisiologia , Animais , Potenciais Somatossensoriais Evocados , Prosencéfalo , Ratos , Fluxo Sanguíneo Regional
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