Hematoma Induction Research Articles

A model to visualize the fate of iron after intracranial hemorrhage using isotopic tracers and elemental bioimaging.

Hemoglobin-iron is a red blood cell toxin contributing to secondary brain injury after intracranial bleeding. We present a model to visualize an intracerebral hematoma and secondary hemoglobin-iron distribution by detecting 58Fe-labeled hemoglobin (Hb) with laser ablation-inductively coupled plasma-mass spectrometry on mouse brain cryosections after stereotactic whole blood injection for different time periods. The generation of 58Fe-enriched blood and decisive steps in the acute hemorrhage formation and evolution were evaluated. The model allows visualization and quantification of 58Fe with high spatial resolution and striking signal-to-noise ratio. Script-based evaluation of the delocalization depth revealed ongoing 58Fe delocalization in the brain even 6 days after hematoma induction. Collectively, the model can quantify the distribution of Hb-derived iron post-bleeding, providing a methodological framework to study the pathophysiological basis of cell-free Hb toxicity in hemorrhagic stroke.

Re-exploring Tumor Necrosis Factor Alpha as a Target for Therapy in Intracerebral Hemorrhage.

Intracerebral hemorrhage (ICH) is a perplexing condition with high mortality and no treatment beyond supportive care. A major portion of the injurious process is takes place during the hours following the development of hematoma. This so-called secondary injury is characterized by an inflammatory cascade that involves a variety of cytokines, including tumor necrosis factor (TNF)-α. Several studies in the rodent model of ICH have shown a rapid increase in brain concentrations of TNF-α following hematoma induction. There is a reasonable body of evidence from experimental models of ICH suggesting that upregulation of TNF-α adjacent to the hematoma is associated with increased peri-hematomal edema, and that inhibition of TNF-α attenuates the formation and progression of this edema and ultimately improves outcomes. Unfortunately, efforts to expand upon these findings have interminably stalled at the pre-clinical phase. A robust clinical study to validate serum TNF-α as a marker for secondary injury in ICH patients is yet to materialize.

CT Evolution of Hematoma and Surrounding Hypodensity in a Cadaveric Model of Intracerebral Hemorrhage.

The evolution of intracerebral hematoma and perihematoma edema in the ultra-early period on computed tomographic (CT) scans in patients with intracerebral hemorrhage (ICH) is not well understood. We aimed to investigate hematoma and perihematoma changes in "neutral brain" models of ICH. One human and five goat cadaveric heads were used as "neutral brains" to provide physical properties of brain without any biological activity or new bleeding. ICH was induced by slow injection of 4 ml of fresh human blood into the right basal ganglia of the goat brains. Similarly, 20 ml of fresh blood was injected deep into the white matter of the human cadaver head in each hemisphere. Serial CT scans of the heads were obtained immediately after hematoma induction and then 1, 3, and 5 hours afterward. Analyze software (AnalyzeDirect, Overland Park, KS, USA) was used to measure hematoma and perihematoma hypodensity volumes in the baseline and follow-up CT scans. The initial hematoma volumes of 11.6 ml and 10.5 ml in the right and left hemispheres of the cadaver brains gradually decreased to 6.6 ml and 5.4 ml at 5 hours, showing 43% and 48% retraction of hematoma, respectively. The volume of the perihematoma hypodensity in the right and left hemisphere increased from 2.6 ml and 2.2 ml in the 1-hour follow-up CT scans to 4.9 ml and 4.4 ml in the 5-hour CT scan, respectively. Hematoma retraction was also observed in all five goat brains ICH models with the mean ICH volume decreasing from 1.49 ml at baseline scan to 1.01 ml at the 5-hour follow-up CT scan (29.6% hematoma retraction). Perihematoma hypodensity was visualized in 70% of ICH in goat brains, with an increasing mean hypodensity volume of 0.4 ml in the baseline CT scan to 0.8 ml in the 5-hour follow-up CT scan. Our study demonstrated that substantial hematoma retraction and perihematoma hypodensity occurs in ICH in the absence of any new bleeding or biological activity of surrounding brain. Such observations suggest that active bleeding is underestimated in patients with no or small hematoma expansion and our understanding of perihematoma hypodensity needs to be reconsidered.

Neuronal tumour necrosis factor-α and interleukin-1β expression in a porcine model of intracerebral haemorrhage: Modulation by U-74389G

Tumour necrosis factor α (TNF-α) and interleukin 1β (IL-1β) are important mediators of intracerebral haemorrhage (ICH) inflammatory response. Lazaroids, established antioxidants and neuroprotectants, have been studied in several brain pathologies. The present study was designed to investigate: a) TNF-α and IL-1β changes, in neurons and b) U-74389G effects, 4 and 24h after haematoma induction in a porcine model of intracerebral haemorrhage.In twenty male landrace pigs (swines) aged 135–150 days old, autologous whole blood was injected around the right basal ganglia territory; in ten of the pigs the lazaroid compound U-74389G was administered. Brain TNF-α and IL-1β immunopositive neurons were determined by immunoarray techniques at 4 and 24h timepoints.After the haematoma induction the number of TNF-α immunopositive neurons ipsilateral to the haematoma was significantly higher compared to the contralateral site at 4h (p<0.0005), while U-74389G significantly reduced the number of TNF-α immunopositive neurons, ipsilateral to the haematoma, at 4h (p=0.002); at 24h, TNF-α immunopositive neurons were found significantly lower in the control group ipsilateral to the haematoma in comparison to 4h timepoint(p<0.0005).The number of IL-1β immunopositive neurons at 4h after the hematoma induction was significantly higher ipsilateral to the haematoma site (p<0.0005). U-74389G had no statistical significant effect.TNF-α and IL-1β, increase in neurons, 4h after the haematoma induction, ipsilateral to the haematoma site. The administration of the antioxidant compound U-74389G, results in early (at 4h) decrease of TNF-α immunopositive neurons but shows no statistical significant effect to IL-1β immunopossitive neurons.

Evacuation of intracerebral hemorrhages by neuroendoscopy with transparent sheath. Experimental study

Abstract Objectives: Endoscopic evacuation of intracerebral hemorrhage (ICH) has been developed in order to reduce the tissue injury that conventional craniotomy could generate. Experimental studies are important to assess the effectiveness of the technique and its modifications. The objectives of this study are to develop in pig an experimental model of endoscopic evacuation of ICHs, to assess effectiveness of surgical evacuation, and to evaluate a new transparent sheath as complement to the endoscopy. Methods: Autologous blood was infused into the frontal lobe white matter in 16 pigs. In the problem group, endoscopic evacuation was performed with the aid of a new transparent sheath, which has outer and inner sheaths with blunt and closed finals. Pigs were sacrificed at 4 h, 24 h and 5 days. The volumes of hematoma and histopathological features were determined. Results: Residual volume of the problem group was significantly 70.09% lower than in control group, without significant differences in injected volumes, in percentage of subarachnoid hemorrhage, and in time interval from hematoma induction to pig´s death. The vital reaction after hemorrhage was similar in both groups. Conclusions: The experimental model developed is useful to assess endoscopic evacuation of ICHs. The endoscopy is an effective technique in the treatment of ICHs, without increasing the vital reaction secondary to hematoma. The new transparent sheath increases the visualization of surgical field and allows a continuous visual control since the beginning of the procedure. Its closed final prevents unwanted injury of the brain by the instruments used to remove the hematoma.

Establishing A Model of Supratentorial Hemorrhage in the Piglet

The most common site of hemorrhage is the basal ganglia, which exhibits the obvious neurological deficits. In the present study, we aimed to develop a model of supratentorial intracerebral hemorrhage (ICH) with neurological deficits in piglets (6.0 to 8.8 kg). A pediatric urinary catheter with two passages and one balloon was introduced through a burr hole into the right striatum. All the animals received balloon inflation, which was performed by injecting 2.5 ml saline into the balloon through one passage. Then each piglet in experimental group (n = 18) received an injection of 1.0-ml autologous arterial blood through the other passage over 2 min and maintained for 5 min. Then, additional 1.5-ml blood was injected over 15 min. Piglets in control group (n = 6) received only balloon inflation without blood injection. CT scanning was performed immediately after surgery. A deep hematoma was successfully induced in 16 out of 18 piglets and the hematoma volume was 1.74 +/- 0.22 ml (n = 5) at 24 hours after surgery. All the piglets with hematoma had behavioral deficits (lame or could not walk) at 24 hours. Tissue damages, such as cell swelling, necrosis and demyelization, appeared at 24 hours in the brain tissues, adjacent to the hematoma, and was aggravated at 48 hours and ameliorated at 7 days after hematoma induction. In conclusion, we have established a simple model of supratentorial ICH in piglets with marked neurological deficits, which is suitable for study of the pathophysiology and treatment of ICH.

Effect of Delayed Mild Brain Hypothermia on Edema Formation After Intracerebral Hemorrhage in Rats

Secondary consequences of intracerebral hemorrhage (ICH) including inflammation, edema, and oxidative damage all contribute to cell death after ICH. Brain hypothermia (BH) has been used as an effective neuroprotective treatment in experimental brain ischemia and traumatic brain injury. In this study, we first attempted to evaluate the effect of delayed mild BH (35 degrees C) on brain edema formation 48 hours after ICH. BH was started 3, 6, 12, and 24 hours after the induction of 100 muL of autologous blood into the basal ganglia (hypothermic [HT]; HT3: n = 4, HT6: n = 6, HT12: n = 11, HT24: n = 6) in rats. To examine the protective mechanism of BH, blood-brain barrier (BBB) permeability to Evans blue, accumulation of polymorphonuclear leukocyte, and oxidative DNA damage in the lesion were compared between normothermic (NT) (37 degrees C) and HT6 rats 48 hours after ICH. Finally, neurologic recovery was assessed using behavioral tests in NT and HT6 rats 48 hours after ICH. Brain water content in the ispilateral basal ganglia was significantly reduced with delayed BT compared with NT (n = 7, 81.8 +/- 0.7% v HT3: 78.9 +/- 0.8%, P < .01; HT6: 78.7 +/- 0.6%, P < .01; HT12: 79.4 +/- 1.1%, P < .01; HT24: 80.3 +/- 0.6%, P < .01). The BBB disruption to Evans blue was significantly reduced with BH (HT6: n = 6) compared with NT (n = 6) rats in the ipsilateral basal ganglia (23.0 +/- 5.2 v 42.3 +/- 4.0 ng/g wet tissue, P < .05). HT6 treatment (n = 6) significantly inhibited the accumulation of polymorphonuclear leukocyte compared with NT treatment (n = 6) (0.43 +/- 0.22 v 1.49 +/- 0.61 DeltaAbs/mg tissue, P < .05). HT6 treatment (n = 3) also significantly reduced oxidative DNA damage determined with 8-hydroxyl-2'-deoxyguanosine compared with NT treatment (n = 3) (92 +/- 18 v 40 +/- 7 pg 8-hydroxyl-2'-deoxyguanosine/mug DNA, P < .05). Furthermore, HT6 treatment (n = 5) significantly improved neurologic recovery assessed with forelimb placing score compared with NT treatment (42.0 +/- 5.8 v 12.0 +/- 3.7, P < .05). In conclusion, mild BH significantly reduces the brain edema formation after ICH, even when the BH is applied 24 hours after hematoma induction in rats. Several neuroprotective mechanisms, including reduced BBB disruption, inflammation and oxidative damage, are suggested in this study.

Addition of intravenous N-methyl-D-aspartate receptor antagonists to local fibrinolytic therapy for the optimal treatment of experimental intracerebral hemorrhages

Fibrinolytic therapy with recombinant tissue plasminogen activator (rtPA) is considered a treatment option in patients with deep-seated intracerebral hemorrhage (ICH). Nevertheless, the results of animal experiments have shown that tPA exerts pleiotropic actions in the brain, including regulation of vasoactivity, amplification of calcium conductance by cleavage of the N-methyl-D-aspartate (NMDA) receptor subunit, and activation of metalloproteinases, which increase excitotoxicity, damage the blood-brain barrier, and worsen edema. The authors investigated whether the noncompetitive NMDA receptor antagonist MK801 can be used as an adjuvant therapy in combination with rtPA to attenuate the unfavorable delayed edema formation and inflammation observed following rtPA therapy in an experimental porcine model of ICH. Twenty pigs were used in this study; MK801 (0.3 mg/kg) was administered to each pig intravenously immediately after hematoma induction and on the 1st and 3rd day after hematoma induction. Ten of the 20 pigs were randomly assigned to fibrinolytic therapy with rtPA (MK801-tPA group), whereas in the remaining 10 control animals (MK801 group) the hematomas were allowed to follow their natural courses of resorption. The extent of edema formation was evaluated using magnetic resonance (MR) imaging volumetry on Days 0, 4, and 10 after hematoma induction and was compared with histopathological changes found at necropsy. The mean edema volumes in these two groups were also compared with that in the group of nine pigs examined in a preceding experimental series, in which the animals' hematomas were only treated with rtPA (tPA group). In the 10 animals in the MK801-tPA group, the mean perihematoma edema volume on MR images had not significantly increased by Day 4 (p < 0.08) or Day 10 (p < 0.35) after hematoma induction. In the 10 animals in the MK801 group, the increase in mean perifocal edema size was significant after 4 days (p < 0.001) and nonsignificant after 10 days (p < 0.09). In the nine animals in the tPA group, the mean edema volume significantly increased by Days 4 (p < 0.002) and 10 (p < 0.03). As suggested by the reduction in delayed edema volume and the inflammatory response, MK801 modifies the neurotoxic properties of rtPA but not those of blood degradation products. Possibly, fibrinolytic therapy of ICH is more beneficial if combined with agents such as MK801.

Perihematoma damage at different time points in experimental intracerebral hemorrhage

The damage degree of neurons in perilesion at different time points was observed in order to explore the optimal operation occasion. Piglet lobar hematomas were produced by pressure-controlled infusions of 2.5 mL autonomous blood into the right frontal hemispheric white matter over 15 min, and the metabolic changes were ambulatorily detected with MRS at 3rd, 12th, 24th and 48th h after hematoma induction. Brain tissues of perihematoma were also obtained at different time points. The transcription level of Bax gene was detected by in situ hybridization and apoptosis by TUNEL technique, and the pathologic change of neurons was observed under an electron microscope. The results showed that the number of Bax positive cells reached the peak at 24 h (79.00 +/- 4.243/5 fields). There was no significant difference in A values between 3 h and 6 h, 12 h (P > 0.05), but there significant difference between 24 h and 3 h, 6 h, 12 h (P < 0.05). The number of apoptotic cells reached the peak at 24 h (P < 0.001), and there was no significant difference between 3 h and 6 h (P = 0.999). The area of the apoptotic cells showed no significant difference between 3 h and 6 h or among 3 h, 6 h and 6 h (P > 0.05). Lac peak mainly occurred at 24 h and 48 h, while on the healthy side, no Lac peak was detectable. The ratio of NAA/Cr presented a descent tendency, but there was no significant difference among the groups before 12 h (P > 0.05), there was very significant difference between 3, 6 and 24, 48 h (P < 0.01). Under electronic microscopy, the neuronal damage surrounding hematoma in 3 to 6 h was milder than in 24 h to 48 h. It was concluded that the secondary apoptosis, damage and metabolic disturbance of the neurons surrounding hematoma was milder in 3-6 h in acute intracerebral hemorrhage, while obviously aggravated in 24-48 h. An effective intervention is needed to reduce secondary damage as soon as possible.

Acute Subdural Hematoma: New Model Delineation and Effects of Coagulation Inhibitors

To develop a highly reproducible rat model and behavioral tests for acute subdural hematoma (ASDH) and to investigate the role of intravascular coagulation and thrombin in the pathogenesis of brain injury in this model. A new method was implemented to inject 200 microl of autologous blood subdurally in rats. Immunohistochemistry was used to investigate intravascular fibrin deposition and thrombin levels in the cortex underlying the ASDH. Effectiveness of systemic heparin, argatroban, or ginkgolide B treatment was determined by histological lesion volume, number of occluded microvessels, and neurological deficits. Neurological deficits were monitored for 7 days after ASDH by use of forelimb placing, forelimb use asymmetry, and corner turn tests. Consistent brain damage and sensorimotor deficits were observed in all animals with ASDH. Histological analysis demonstrated occluded microvessels and enlarged perivascular spaces in the underlying cortex starting 1 hour after hematoma induction. Fibrin and thrombin immunoreactivity were increased in the lesioned cortical parenchyma at 4 and 24 hours. However, no intravascular fibrin deposition was detected. Heparin induced hemorrhagic transformation in the cortical lesion and did not attenuate microvessel occlusion. Argatroban and ginkgolide B did not induce hemorrhage but failed to improve microvessel occlusion, lesion volume, and neurological deficits. Intravascular coagulation and thrombin are not the major mediators of brain damage after ASDH. The model and behavioral tests presented in this study can be used to investigate other putative mechanisms of injury and to test future therapeutic interventions in ASDH.

Minor inflammation after surgical evacuation compared with fibrinolytic therapy of experimental intracerebral hemorrhages

Objectives: Toxic components released from the intracerebral blood clot, such as thrombin and hemoglobin, potentially trigger brain edema formation and therefore favor an early evacuation of the clot. Despite a significant reduction in hematoma size in our porcine model of hematoma induction by injecting autologous blood ICP-controlled into the right frontal white matter with subsequent fibrinolysis using recombinant tissue-plasminogen activator (rt-PA) and aspiration of the liquefied clot (n=9), local rt-PA promoted delayed perihematomatous edema formation and invoked a substantial inflammatory reaction compared with controls (n=11).Methods: We therefore modified our formerly developed porcine model of intracerebral hemorrhage in removing the hematoma by open craniotomy and suction of the clot in seven animals. The residual hematoma size and extent of perifocal edema were evaluated over 10 days on planimetry of the MRI data, and correlated to the histopathological changes of edema and inflammation found at autopsy.Results: The edema volume on day 4 was significantly less in the surgical group compared with the lysis group (p<0.03). On day 10, however, the difference in edema size was not statistically significant compared with the lysis group (p<0.07) and the control group (p<0.09). The inflammatory response was minor compared with the lysis and control group.Discussion: In conclusion, despite a significant reduction in hematoma size by surgical removal of the clot, only the inflammatory response, but not the extent of delayed edema can be positively influenced.

Tempol, a novel stable nitroxide, reduces brain damage and free radical production, after acute subdural hematoma in the rat.

Recent studies have shown that there is increased production of deleterious free radicals following acute subdural hematoma (ASDH). Scavenging them may therefore be of therapeutic benefit. Nitroxides are new, low molecular weight, cell permeable superoxide dismutase mimics. This study investigated the neuroprotective effect of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol) following ASDH in the rat. Twenty-one male Sprague-Dawley rats were used in two studies: (1) a volumetric study of ischemic brain damage (n = 10); and (2) a microdialysis study measuring free radical generation after ASDH (n = 11). Ten minutes after induction of hematoma, the animals received 10 mg/kg Tempol or vehicle intravenously. In the volumetric study, 4 h after treatment, the rats were perfused, the brain removed, cut into serial 12-microm coronal sections, and stained. Ischemic areas were measured in eight predetermined stereotactic planes. In the microdialysis study, free radical production was measured using the salicylate trapping technique by quantifying 2,3-dihydrobenzoic acid (2,3-DHBA) and 2,5-DHBA using HPLC. In the volumetric study, Tempol treatment significantly reduced infarct volumes; 100.2 +/- 15.7 mm3 in Tempol-treated animals compared with 171.5 +/- 13.6 mm3 in controls (42% reduction, p = 0.0005). The microdialysis study demonstrated an early twofold increase of free radical production at 30 min, and returning to the baseline levels in controls. However, in Tempol-treated animals, this early surge was attenuated, and all measured values remained around the baseline levels throughout the experiments. Tempol thus provides significant neuroprotective effect in a rat model of ASDH, related to attenuation of superoxide radical production. The use of these low molecular weight, cell-permeable agents, which readily cross the blood-brain barrier and enter cells, thus appears indicated for acute pathologies, ASDH.

The long-term effect of recombinant tissue-plasminogen-activator (rt-PA) on edema formation in a large-animal model of intracerebral hemorrhage

Hematoma puncture, fibrinolysis, and aspiration of the liquefied clot is a promising new treatment strategy for large intracerebral hemorrhages (ICH). Characteristics of the cellular injury and neuronal and glial cell death associated with ICH and the administration of fibrinolytic agents still need to be defined. We developed a porcine model to study the histopathological effects of recombinant tissue-Plasminogen-Activator (rt-PA) on perihematomatous cell integrity. In 20 pigs, lobar hematomas were induced by intracranial pressure (ICP)-controlled injections of 7.6 ± 1.6 ml of autologous blood into the white matter of the right frontal hemisphere. In nine animals, the clots were lysed with rt-PA, thereby facilitating aspiration 2 h after hematoma induction. In 11 control pigs, the hematoma resorption followed its natural course. The rate of hematoma reduction and edema formation over 10 days was evaluated on planimetry of the MRI data and correlated to the histopathological changes found at autopsy. Although rt-PA significantly accelerated clot resolution compared to controls ( p< 0.02), the increase of perihematomatous edema volume within 10 days was not significantly ameliorated in rt-PA-treated animals compared to controls on MRI. The extent of inflammatory infiltrates on histology was more pronounced in animals treated with rt-PA. In conclusion, despite significant reduction in the size of the hematoma clot liquefication with rt-PA and aspiration invokes a substantial inflammatory response when studied after 10 days and does not result in a reduction of the perihematomatous edema.

Characterization of the diarylether sulfonylester (-)-(R)-3-(2-hydroxymethylindanyl-4-oxy)phenyl-4,4,4-trifluoro-1-sulfonate (BAY 38-7271) as a potent cannabinoid receptor agonist with neuroprotective properties.

(-)-(R)-3-(2-Hydroxymethylindanyl-4-oxy)phenyl-4,4,4-trifluoro-1-sulfonate (BAY 38-7271) is a new high-affinity cannabinoid receptor subtype 1 (CB1 receptor) ligand (K(i) = 0.46-1.85 nM; rat brain, human cortex, or recombinant human CB1 receptor), structurally unrelated to any cannabinoid receptor ligand known so far. BAY 38-7271 was characterized as a CB1 receptor agonist in 5-[gamma(35)S]-thiophosphate triethylammonium salt binding assays using rat or human CB1 receptors. In the rat hypothermia assay, BAY 38-7271 induced a dose-dependent reduction in body temperature (minimal effective dose = 6 microg/kg, i.v.); whereas in rats trained to discriminate the CB1/CB2 receptor agonist (-)-cis-3-[2-hydroxy-4(1,1-dimethyl-heptyl)phenyl]-trans-4-(3-hydroxypropyl) cyclohexanol (CP 55,940; 0.03 mg/kg, i.p.) from vehicle, BAY 38-7271 induced complete generalization (3 microg/kg, i.v.). In both in vivo models, a specific CB1 receptor-mediated mechanism was confirmed by demonstrating that the effects of CP 55,940 and BAY 38-7271 were blocked by pretreatment with the selective CB1 receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamidehydrochloride. In the rat traumatic brain injury model, BAY 38-7271 demonstrated highly potent and efficient neuroprotective properties when administered as a 4-h infusion immediately after induction of subdural hematoma (70% infarct volume reduction at 100 ng/kg/h). Even when applied with a 3-h delay, a significant neuroprotective efficacy could be observed (59% infarct volume reduction at 300 ng/kg/h). The neuroprotective potential of BAY 38-7271 was confirmed in a rat model of focal cerebral ischemia induced by permanent occlusion of the middle cerebral artery. It is concluded that the CB1/CB2 receptor agonist BAY 38-7271 shows pronounced neuroprotective properties that do not result from drug-induced hypothermia and that occur in a dose range devoid of typical cannabinoid-like side effects.

Effects of mild hypothermia and alkalizing agents on brain injuries in rats with acute subdural hematomas.

Brain ischemia is the leading pathopysiological mechanism in the development of secondary brain damage after acute subdural hematoma (SDH). Hypothermia has been employed as an effective cerebroprotective treatment on brain injuries, but the control of the general condition is very difficult under hypothermia, and various severe complications have been reported. Cerebral acidosis in the ischemic area is one of the important factors augmenting the brain edema formation. Tris-(hydroxymethyl)-aminomethane (THAM) has been used as an alkalizing agent for acidosis on brain injury and is reported to be effective. In the present study, we used a rat acute SDH model to assess the effect of mild (35 degrees C) hypothermia and THAM combined treatment on brain water content, brain ischemia, and blood-brain barrier (BBB) permeability at 4 h after hematoma induction. Mild hypothermia did not significantly reduce the brain water content beneath the hematoma (79.5 +/- 0.2%) compared to normothermia (80.2 +/- 0.2%), but mild hypothermia combined to THAM resulted in a significant reduction (78.7 +/- 0.0%; p < 0.01). Combined with mild hypothermia, THAM treatment significantly reduced the Evan's blue extravasation (35 +/- 7 ng/g wet tissue; p < 0.05) compared to normothermia (63 +/- 7 ng/g wet tissue). Furthermore, the volume of infarction at 24 h after the hematoma induction (54 +/- 3 mm(3); p < 0.01) was significantly smaller by the combined treatment compared with normothermia (70 +/- 2 mm(3)). The present findings indicate that mild hypothermia of 35 degrees C combined with THAM presents a potent cerebroprotective strategy. The protection of the BBB is one of the possible cerebroprotective mechanisms in this rat acute SDH model.

Effects of brain hypothermia on brain edema formation after intracerebral hemorrhage in rats.

Patients with intracerebral hemorrhage (ICH) may deteriorate progressively after the initial ictus because of the brain edema around the hematoma. Recently, thrombin has become known to play an important role in the brain edema formation after ICH. In this study, we examined the effect of brain hypothermia on brain edema formation after hematoma and thrombin injection into the brain in rats and clarified the mechanism of hypothermia on brain damage. Anesthetized Sprague-Dawley rats received an injection of 100 microL of autologous blood or 10 units of bovine thrombin into the basal ganglia. Animals were divided into the normothermic and hypothermic groups, which were housed in a room at 25 degrees C and in a cold room at 5 degrees C respectively, for 24 hours. Brain water content was significantly reduced with hypothermia in the cortex (80.8 vs. 79.7% p < 0.05) after hematoma induction. After thrombin injection, brain water content was also significantly reduced with hypothermia in the basal ganglia (84.5 vs. 82.2%; p < 0.01), accompanied by a significant reduction in blood-brain barrier (BBB) permeability to Evan's blue (29.4 vs. 11.6 ng/g tissue; p < 0.05) and in accumulation of polymorphonuclear leukocytes (3.03 vs. 0.27 U of myeloperoxidase/g tissue; p < 0.01). This study indicates that brain hypothermia significantly reduces brain edema formation after hematoma and thrombin injection into the brain in rats. Inhibition of thrombin-induced BBB breakdown and inflammatory response with hypothermia appear to contribute to brain protection in this model.

Mechanisms of edema formation after intracerebral hemorrhage: effects of extravasated red blood cells on blood flow and blood-brain barrier integrity.

Red blood cell (RBC) lysis contributes to brain edema formation after intracerebral hemorrhage (ICH), and RBC hemolysate (oxyhemoglobin) has been implicated to be a spasminogen in subarachnoid hemorrhage. Whether cerebral ischemia contributes to brain edema formation after ICH remains unclear, however. The aims of this study were to test whether extravasation of RBCs induces cerebral ischemia and/or blood-brain barrier disruption in a rat ICH model characterized by perihematomal brain edema. In this study, 87 pentobarbital-anesthetized Sprague-Dawley rats were used. In each animal, saline, packed RBCs, or lysed RBCs were injected into the right caudate nucleus. Sham injections served as controls. Regional cerebral blood flow, brain water and ion contents, blood-brain barrier integrity, and plasma volume were measured. Intraparenchymal infusion of lysed RBCs caused severe brain edema by the first day but did not induce ischemic cerebral blood flows. In contrast, blood-brain barrier permeability increased during the first day after infusion of lysed RBCs (a 3-fold increase) and 3 days after infusion of packed RBCs (a 4-fold increase). These results suggest that ischemia is not present at 24 or 72 hours after hematoma induction by injection of intact or lysed RBCs. RBC constituents that appear after delayed lysis, however, increase blood-brain barrier permeability, which contributes to edema formation.

Effects of hypothermia on intracranial pressure and brain edema formation: studies in a rat acute subdural hematoma model.

Acute subdural hematoma (SDH) is the most common mass lesion in severe head injury, and brain ischemia is the leading pathophysiological mechanism in the development of secondary brain damage following SDH. Hypothermia has been employed as an effective neuroprotective procedure in clinical and laboratory studies on cerebral ischemic and contusional injuries. In the present study, we used a rat acute SDH model to assess the effect of hypothermia on the intracranial pressure (ICP) and also on the brain edema formation at 4 h after hematoma induction. Mild (34 degrees C) and moderate (32 degrees C) hypothermia did not significantly affect the ICP or cerebral perfusion pressure, but they were associated with a significant lower cortical brain edema formation beneath the hematoma (81.09 +/- 0.49%, p<0.05; and 80.88 +/- 0.17%, p<0.01) when compared with the normothermic control group (81.65 +/- 0.52%). This reduction in brain edema formation was comparable to the results of MK-801 treatment (80.95 +/- 0.35%, p<0.01). The present findings indicate that hypothermia represents a potent neuroprotective strategy. The possible protective mechanisms of hypothermic protection afforded in this rat acute SDH model are discussed.

Effects of hypothermia on intracranial hemodynamics and ischemic brain damage-studies in the rat acute subdural hematoma model.

Brain ischemia is the leading pathophysiological mechanism in the development of secondary brain damage after subdural hematoma (SDH). Hypothermia has been used as the effective neuroprotective treatment in clinical and laboratory studies of ischemic brain injury. In this study, we have examined the rat acute SDH model to assess the effect of hypothermia upon intracranial hemodynamics and also upon ischemic brain injury 4 hours after the induction of hematoma. Moderate hypothermia (32 degrees C) did not affect the intracranial pressure nor cerebral perfusion pressure, and it significantly reduced cortical brain edema formation underneath the hematoma (80.88 +/- 0.17%; p < 0.01) compared with the normothermic control group (81.65 +/- 0.52%). This reduction in brain edema formation was comparable to the result of MK-801 (2 mg/kg) treatment (80.95 +/- 0.35%; p < 0.01). Ischemic brain damage detected by H-E staining was also significantly reduced in the hypothermia and MK-801 treated groups (59.1 +/- 12.3 mm3 and 66.4 +/- 13.8 mm3; p < 0.01 and p < 0.05) compared with the normothermic control group (86.6 +/- 20.7 mm3). In conclusion, the present study demonstrates that hypothermia is a potent neuroprotective method and an inhibition of the glutamate excitotoxic process may contribute the protective mechanisms of hypothermia in this rat acute SDH model.

Ultra-early clot aspiration after lysis with tissue plasminogen activator in a porcine model of intracerebral hemorrhage: edema reduction and blood-brain barrier protection.

Ultra-early hematoma evacuation (< 4 hours) after intracerebral hemorrhage (ICH) may reduce mass effect and edema development and improve outcome. To test this hypothesis, the authors induced lobar hematomas in pigs. The authors infused 2.5 ml of blood into the frontal cerebral white matter in pigs weighing 8 to 10 kg. In the treatment group, clots were lysed with tissue plasminogen activator ([tPA], 0.3 mg) and aspirated at 3.5 hours after hematoma induction. Brains were frozen in situ at 24 hours post-ICH and hematomal and perihematomal edema volumes were determined on coronal sections by using computer-assisted morphometry. Hematoma evacuation rapidly reduced elevated cerebral tissue pressure from 12.2+/-1.3 to 2.8+/-0.8 mm Hg. At 24 hours, prior clot removal markedly reduced hematoma volumes (0.40+/-0.10 compared with 1.26+/-0.13 cm3, p < 0.005) and perihematomal edema volumes (0.28+/-0.05 compared with 1.46+/-0.24 cm3, p < 0.005), compared with unevacuated control lesions. Furthermore, no Evans blue dye staining of perihematomal edematous white matter was present in brains in which the hematomas had been evacuated, compared with untreated controls. Hematomas were quickly and easily aspirated after treatment with tPA, resulting in significant reductions in mass effect. Hematoma aspiration after fibrinolysis with tPA enabled removal of the bulk of the hematoma (> 70%), markedly reduced perihematomal edema, and prevented the development of vasogenic edema. These findings in a large-animal model of ICH provide support for clinical trials that include the use of fibrinolytic agents and ultra-early stereotactically guided clot aspiration for treating ICH.