Early hemodynamic changes in experimental intracerebral hemorrhage

Spontaneous intracerebral hemorrhage: a review

Spontaneous intracerebral hemorrhage (SICH) is a blood clot that arises in the brain parenchyma in the absence of trauma or surgery. This entity accounts for 10 to 15% of all strokes and is associated with a higher mortality rate than either ischemic stroke or subarachnoid hemorrhage. Common causes include hypertension, amyloid angiopathy, coagulopathy, vascular anomalies, tumors, and various drugs. Hypertension, however, remains the single greatest modifiable risk factor for SICH. Computerized tomography scanning is the initial diagnostic modality of choice in SICH, and angiography should be considered in all cases except those involving older patients with preexisting hypertension in thalamic, putaminal, or cerebellar hemorrhage. Medical management includes venous thrombosis prophylaxis, gastric cytoprotection, and aggressive rehabilitation. Anticonvulsant agents should be prescribed in supratentorial SICH, whereas the management of hypertension is controversial.

To date, nine prospective randomized controlled studies have been conducted to compare surgical and medical management of SICH. Although definitive evidence favoring surgical intervention is lacking, there is good theoretical rationale for early surgical intervention. Surgery should be considered in patients with moderate to large lobar or basal ganglia hemorrhages and those suffering progressive neurological deterioration. Elderly patients in whom the Glasgow Coma Scale score is less than 5, those with brainstem hemorrhages, and those with small hemorrhages do not typically benefit from surgery. Patients with cerebellar hemorrhages larger than 3 cm, those with brainstem compression and hydrocephalus, or those exhibiting neurological deterioration should undergo surgical evacuation of the clot. It is hoped that the forthcoming results of the International Surgical Trial in IntraCerebral Hemorrhage will help formulate evidence-based recommendations regarding the role of surgery in SICH.

Experimental intracerebral hemorrhage in the mouse: histological, behavioral, and hemodynamic characterization of a double-injection model

BACKGROUND AND PURPOSE

A major limitation of intracerebral hemorrhage (ICH) research is the lack of reproducible animal models. The present study was conducted to validate in the mouse the double-injection method of ICH initially developed in the rat. We investigated the effect of intrastriatal injection of blood or cerebrospinal fluid (CSF) on cerebral blood flow (CBF), neurological score, hematoma volume, and brain swelling.

METHODS

Male C57BL/6 mice were anesthetized with halothane/nitrous oxide delivered by face mask. Rectal and cranial temperatures were regulated at 37 degrees C to 37.5 degrees C. Mice were placed in a stereotactic frame, and a 30-gauge stainless steel cannula was introduced through a burr hole into the left striatum. Each mouse received a 5-microL injection of either whole blood or CSF (over 3 minutes), followed 7 minutes later by 10 microL injected over 5 minutes. The injection cannula was slowly withdrawn 10 minutes after the second injection. Control mice had only cannula insertion. CBF was studied by laser Doppler perfusion imaging. Neurological status was evaluated on days 1 and 2. After 2 days, hematoma volume and brain swelling were calculated.

RESULTS

Physiological values were stable. Mice with ICH but not those with CSF or cannula alone had a marked, persistent neurological deficit and a highly reproducible hematoma, whose mean+/-SEM volume was 2.0+/-0.2 mm3 compared with a lesion size of 0.2+/-0.1 mm3 in mice with CSF. Residual swelling of the ipsilateral hemisphere at 48 hours was 5.7% in the hematoma and 1.5% in the CSF groups. Relative CBF in the neocortex ipsilateral to the injection site declined by approximately 45% to 60% during the first 20 minutes after cannula insertion/injection in all groups but began to renormalize at approximately 25 to 30 minutes in the CSF and cannula-only groups; in the hematoma group, cortical hypoperfusion of approximately 35% to 50% persisted during the 90-minute measurement period.

CONCLUSIONS

The present ICH model in mice produces a consistent neurological deficit, hypoperfusion, hematoma volume, and brain swelling. This model closely mimics human hypertensive basal ganglionic ICH and should be useful for the evaluation of pharmaceutical therapies. Laser Doppler perfusion imaging is a useful new technique to quantify relative CBF changes and can be used for studies of dynamic changes of CBF in this in vivo model of ICH in mice.

Extracellular glutamate and other amino acids in experimental intracerebral hemorrhage: an in vivo microdialysis study

OBJECTIVE

To determine whether extracellular concentrations of glutamate and other amino acids are significantly elevated after intracerebral hemorrhage and, if so, the temporal characteristics of these changes. Although the role of excitotoxic amino acids, particularly that of glutamate, has been described in ischemic stroke and head trauma, no information exists regarding their possible contribution to the pathogenesis of neuronal injury in intracerebral hemorrhage.

DESIGN

Prospective, controlled, laboratory trial.

SETTINGS

Animal research laboratory.

SUBJECTS

Sixteen anesthetized New Zealand rabbits.

INTERVENTION

We introduced intracerebral hemorrhage in each of eight anesthetized New Zealand rabbits by injecting 0.4 mL of autologous blood under arterial pressure into the deep gray matter of the cerebrum.

MEASUREMENTS AND MAIN RESULTS

Extracellular fluid samples were collected from the perihematoma region and contralateral (right) hemisphere by in vivo microdialysis at 30-min intervals for 6 hrs. Corresponding samples were similarly collected from both hemispheres in each of eight control animals that underwent needle placement without introduction of a hematoma. Concentrations of amino acids (glutamate, aspartate, asparagine, glycine, taurine, and gamma-aminobutyric acid) in the samples were measured by use of high-pressure liquid chromatography with fluorescence detection. Glutamate concentrations (mean +/- sem) were significantly higher in the hemisphere ipsilateral to the hematoma than in the contralateral hemisphere (92 +/- 22 pg/microL vs. 22 +/- 6 pg/microL) at 30 mins after hematoma creation. A significant increase was observed at 30 mins posthematoma creation in the hemisphere ipsilateral to the hematoma compared with the baseline value. A nonsignificant increase in glutamate concentration persisted in the hemisphere ipsilateral to the hematoma, ranging from 134% to 187% of baseline value between 1 and 5 hrs after hematoma creation. In the hemisphere ipsilateral to the hematoma, a three-fold increase in the concentration of glycine was observed at 30 mins after hematoma creation compared with the baseline level (890 +/- 251 pg/microL vs. 291 +/- 73 pg/microL). There was a significant difference between the hemisphere ipsilateral to the hematoma compared with the ipsilateral (corresponding) hemisphere of the control group at 30 mins posthematoma (890 +/- 251 pg/microL vs. 248 +/- 66 pg/microL). A similar transient increase was observed in taurine and asparagine concentrations at 30 mins after hematoma creation, compared with baseline measurements. Taurine concentrations in the hemisphere ipsilateral to the hematoma were significantly higher than the ipsilateral hemisphere of the control group (622 +/- 180 pg/microL vs. 202 +/- 64 pg/microL) at 30 mins after hematoma creation.

CONCLUSIONS

The present study suggests that glutamate and other amino acids accumulate transiently in extracellular fluids in the perihematoma region during the early period of intracerebral hemorrhage. The exact role of these amino acids in the pathogenesis of neuronal injury observed in intracerebral hemorrhage needs to be defined.

Role of thrombin in CNS damage associated with intracerebral haemorrhage: opportunity for pharmacological intervention?

Intracerebral haemorrhage (ICH) results in high mortality and morbidity. The most important causes of neurological deterioration after ICH are progression of oedema and injury to nerve cells and axons surrounding the haematoma, as well as haematoma enlargement. Recent studies have indicated that thrombin, formed upon clotting of the haematoma, plays an important role in these processes. As opposed to conventional therapeutic approaches, administration of a thrombin inhibitor could effectively limit oedema formation and neuronal damage, improving survival and functional outcome. A small, preliminary clinical trial has suggested that antithrombin therapy with intravenously administered argatroban may be useful in treatment of ICH. Randomised, controlled studies are needed to confirm these initial findings.

Fibrinolysis therapy achieved with tissue plasminogen activator and aspiration of the liquefied clot after experimental intracerebral hemorrhage: rapid reduction in hematoma volume but intensification of delayed edema formation

OBJECT

Fibrinolysis therapy accomplished using tissue plasminogen activator (tPA) and aspiration is considered to be a viable alternative to microsurgery and medical therapy for the treatment of deep-seated spontaneous intracerebral hematomas (SICHs). Tissue plasminogen activator is a mediator of thrombin- and ischemia-related delayed edema. Because both thrombin release and ischemia occur after SICH, the authors planned to investigate the effect of fibrinolytic therapy on hematoma and delayed edema volume.

METHODS

A spherical hematoma was created in the frontal white matter of 18 pigs. In the tPA-treated group (nine pigs), a mean of 1.55 ml tPA was injected into the clot and the resulting liquefied blood was aspirated. Magnetic resonance (MR) imaging was performed on Days 0 (after surgery), 4, and 10, and the volumes of hematoma and edema were determined. In the animals not treated with tPA (untreated group; nine pigs), the volume of hematoma dropped from 1.43+/-0.42 ml on Day 0 to 0.85+/-0.28 ml on Day 10. In the tPA-treated group, the volume of hematoma was reduced from 1.51 +/- 0.28 ml on Day 0 to 0.52 +/- 0.39 ml on Day 10. In comparison with the untreated group, the reduction in hematoma volume was significantly accelerated (p = 0.02). In the untreated group, perihematomal edema increased from 0.32 +/- 0.61 ml to 1.73 +/- 0.73 ml on Day 4, before dropping to 1.17 +/- 0.92 ml on Day 10. In the tPA-treated group, the volume of the edema increased from 0.09 +/- 0.21 ml on Day 0 to 1.93 +/- 0.79 ml on Day 4, and further to 3.34 +/- 3.21 ml on Day 10. The increase in edema volume was significantly more pronounced in the tPA-treated group (p = 0.04).

CONCLUSIONS

Despite a significantly accelerated reduction in hematoma volume, the development of delayed perifocal edema was intensified by fibrinolytic therapy, which is probably related to the function of tPA as a mediator of edema formation after thrombin release and ischemia. Further experimental and clinical investigations are required to establish the future role of fibrinolysis in the management of SICH.

Cerebral blood flow changes associated with intracerebral hemorrhage

Recent advances have furthered our understanding of changes in CBF after ICH. Recent evidence from experimental and clinical studies has not supported the role of CBF changes in the pathogenesis of neuronal injury. A better understanding of these changes in ICH has modified the basis for formulating treatment strategies and developing innovative therapies.

Experimental animal models of intracerebral hemorrhage

Experimental animal ICH models are able to reproduce the overall important pathophysiologic events documented in human ICH, including edema development, markedly reduced metabolism, and tissue pathologic responses. Thus, ICH models serve as an important tool for new understanding of the mechanisms underlying brain injury after an intracerebral bleed. Currently, ongoing studies in several laboratories using these models investigating secondary inflammatory responses as well as intracellular signaling and molecular events are expected to provide therapeutic targets for treating ICH. Future studies should also be directed at one aspect of ICH modeling that has received little attention--potential differences in the hemostatic systems and physical and biochemical properties of clots in animals that might make their susceptibility to aspiration and/or fibrinolytic drugs and rates of rehemorrhage different than in human beings. Also, future efforts should be directed toward the development of a model that mimics the pathophysiologic processes that lead to spontaneous ICH, progression of hemorrhage, and the recurrence of bleeding in human beings. This model would not only provide better understanding of the dynamic events leading to ICH and tissue injury but should also lead to the development of highly effective pharmacologic and surgical treatments.

Hypoxia-inducible factor-1alpha accumulation in the brain after experimental intracerebral hemorrhage

Hypoxia-inducible factor-1 (HIF-1), a transcription factor composed of HIF-1alpha and HIF-1beta protein subunits, has been implicated in cellular protection and cell death in cerebral ischemia. The extent to which HIF-1 plays a role in brain pathology during intracerebral hemorrhage (ICH) is unknown. This study determined whether HIF-1alpha is upregulated at different time points in a rat model of ICH and the role of thrombin and red blood cell lysis in upregulation. Recently, thrombin has been implicated as a nonhypoxic regulator of HIF-1alpha in cultured smooth-muscle cells. Male Sprague-Dawley rats received intracerebral infusions of saline, autologous whole blood, blood plus hirudin, thrombin, thrombin plus hirudin, or lysed erythrocytes. Rats were killed at different time points for Western blot analysis, immunohistochemistry, immunofluorescent double staining, and reverse transcription polymerase chain reaction measurements of HIF-1alpha. HIF-1alpha protein levels increased without changing HIF-1alpha messenger RNA levels after intracerebral infusions of blood, thrombin, and lysed erythrocytes. HIF-1alpha positive cells, which proved to be neurons, were found in the brain after ICH. Hirudin, a specific thrombin inhibitor, reduced HIF-1alpha upregulation in response to both thrombin and blood. This study demonstrates that perihematomal HIF-1alpha protein is upregulated after ICH. This phenomenon is an early response of brain parenchyma to the clot. Thrombin and erythrocyte lysate are involved in HIF-1alpha upregulation through reducing HIF-1alpha degradation.

Marked anemic hypoxia deteriorates cerebral hemodynamics and brain metabolism during massive intracerebral hemorrhage

The present study was undertaken to investigate the influence of imposed anemic hypoxia on cerebral hemodynamics and metabolism in a condition of massive ICH. Two groups of eight dogs, with a target hemoglobin concentration of 12 g/dl in nonanemic and 6 g/dl in anemic group, were included. Before the onset of the insult, anemic group had a significant reduction (p<0.05) in cerebral arteriovenous oxygen content difference (AVDO2), accompanied with a significant rise (p<0.05) in flow velocity (FV) of the basilar artery and cerebral extraction fraction of oxygen (CEO2) and a lower brain-tissue lactate clearance than did nonanemic group. Shortly after ICH, both groups displayed significant reductions (p<0.05) in FV, CEO2 and AVDO2, and simultaneous rises in arteriovenous lactate concentrations. In nonanemic group, the CEO2 and AVDO2 gradually returned after an initial decrease, and then the arteriovenous lactate concentrations slowly decreased. In contrast, anemic group showed progressive reductions in CEO2 and AVDO2 associated with persistent rises in arteriovenous lactate concentrations. Consequently, anemic group exhibited significantly greater brain-tissue lactate clearances (p<0.05), occurring at 10 min and 5 h postinjury, than did nonanemic group, although the former had relatively higher levels of CEO2 up to 3 h postinjury. We conclude that anemic hypoxia modulates a favorable change in cerebral hemodynamics and oxygenation, while it progressively deteriorates after an initial reduction during massive ICH, thus facilitating cerebral anaerobic glycolysis in biphasic periods. These results point to a complex interaction between cerebral hemodynamics, oxygen supply and glycolysis homeostasis upon the addition of anemic hypoxia in severe stress conditions of the brain.

Neuronal, but not microglial, accumulation of extravasated serum proteins after intracerebral hemolysate exposure is accompanied by cytochrome c release and DNA fragmentation

Vasogenic edema after oxidative injury has been accompanied by intracellular accumulation of serum proteins and nuclear damage. This study sought to determine whether serum protein accumulation, along with other markers of brain injury, was present after exposure to intracerebral hemolysate, an oxidant model of intracerebral hemorrhage (ICH). Saline (n = 24) or hemolysate (n = 30) was injected into the caudate-putamen of adult Sprague-Dawley rats. Compared with saline, hemolysate deposition was associated with intracellular accumulation of serum proteins as evidenced by Evans blue uptake in neurons and microglia at 4 and 24 hours. Intracellular Evans blue colocalized with DNA fragmentation detected by nick end-labeling and whose presence was confirmed by gel electrophoresis. Immunoblots of cytosolic fractions confirmed cytochrome c release. Immunostaining established colocalization of cytosolic cytochrome c and intracellular Evans blue at 4 hours. At 24 hours, cytosolic cytochrome c was evident in astrocytes surrounding Evans blue-positive cells. Immunoblot analysis and immunostaining revealed HSP70 induction at 24 hours in regions adjacent to intracellular serum accumulation. Neuronal accumulation of extravasated serum proteins in this model of ICH was associated with cytochrome c release, DNA fragmentation, and cell death. Stress protein induction in adjacent regions suggested that vasogenic edema might have exacerbated cellular dysfunction and cell death after ICH.

Absence of early proinflammatory cytokine expression in experimental intracerebral hemorrhage

OBJECTIVE

We sought to analyze the regional concentrations of proinflammatory cytokines in the acute period of intracerebral hemorrhage (ICH) and to test the hypothesis that ICH is associated with the expression of proinflammatory cytokines in the acute period. Although the expression of cytokines and their role in neuronal injury and inflammation is well characterized in cerebral ischemia and head injury, no information exists regarding expression of cytokines in ICH.

METHODS

We introduced ICH in eight anesthetized mongrel dogs by autologous blood injection (6 ml) under arterial pressure in the deep white matter adjacent to the left basal ganglia. Samples of arterial blood and cerebrospinal fluid were collected, and tissue extracts were prepared from different regions of the brain for immunoassay of tumor necrosis factor alpha, interleukin (IL)-1beta, and IL-6 concentrations in animals with and without ICH.

RESULTS

The tumor necrosis factor a levels (+/- standard error) in the cerebrospinal fluid 1 hour after ICH did not differ significantly between the ICH group and the control group (7.1 +/- 1.3 pg/ml versus 10.8 +/- 2.3 pg/ml, P = 0.22). Levels in the perihematoma region in the ICH group (96.6 +/- 3.1 pg/ml) were not significantly different from those in the control group (93.4 +/- 6.7 pg/ml, P = 0.7). IL-6 levels (+/- standard error) in the perihematoma region in the ICH group (116.3 +/- 13.3 pg/ml) did not differ significantly from those in corresponding regions in the control group (122.3 +/- 12.8 pg/ml, P = 0.7). IL-1beta levels were below 5 pg/ml in serum, cerebrospinal fluid, and extracts of different brain regions.

CONCLUSION

The early pathophysiology of ICH does not involve significant expression of tumor necrosis factor a either in the perihematoma region or other regions of the brain. The observation suggests that the pathophysiology of ICH in the acute period is different from both cerebral ischemia and traumatic brain injury.

Hypoperfusion without ischemia surrounding acute intracerebral hemorrhage

A zone of hypoperfusion surrounding acute intracerebral hemorrhage (ICH) has been interpreted as regional ischemia. To determine if ischemia is present in the periclot area, the authors measured cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and oxygen extraction fraction (OEF) with positron emission tomography (PET) in 19 patients 5 to 22 hours after hemorrhage onset. Periclot CBF, CMRO2, and OEF were determined in a 1-cm-wide area around the clot. In the 16 patients without midline shift, periclot data were compared with mirror contralateral regions. All PET images were masked to exclude noncerebral structures, and all PET measurements were corrected for partial volume effect due to clot and ventricles. Both periclot CBF and CMRO2 were significantly reduced compared with contralateral values (CBF: 20.9 +/- 7.6 vs. 37.0 +/- 13.9 mL 100 g(-1) min(-1), P = 0.0004; CMRO2: 1.4 +/- 0.5 vs. 2.9 +/- 0.9 mL 100 g(-1) min(-1), P = 0.00001). Periclot OEF was less than both hemispheric OEF (0.42 +/- 0.15 vs. 0.47 +/- 0.13, P = 0.05; n = 19) and contralateral regional OEF (0.44 +/- 0.16 vs. 0.51 +/- 0.13, P = 0.05; n = 16). In conclusion, CMRO2 was reduced to a greater degree than CBF in the periclot region in acute ICH, resulting in reduced OEF rather than the increased OEF that occurs in ischemia. Thus, the authors found no evidence for ischemia in the periclot zone of hypoperfusion in acute ICH patients studied 5 to 22 hours after hemorrhage onset.

Characteristics of sustained blood-brain barrier opening and tissue injury in a model for focal trauma in the rat

Minor stab wounding of rodent brain by needle or razor blade is a standard model for immunohistochemical investigations of secondary neuronal degeneration and scarring. Opening of the blood-brain barrier (BBB) to plasma molecules and inflammatory cells is integral to the secondary injury process. To facilitate quantitative study of these BBB phenomena, we tested the utility of a stereotaxic wire knife as a minimally invasive way for modeling of focal trauma and bleeding in brain parenchyma and substantial, reproducible BBB damage. Adult rats were anesthetized, and through a skull burr hole, the 0.3-mm dia guide cannula housing a laterally extendable tungsten wire (0.13 mm dia) was inserted into the right striatum. A layering of horizontal disk-like cuts (3 mm dia) was made, producing a cylindrical lesion of approximately 18 mm3 volume, approximately 2.7% of the cerebral hemisphere. Transfer constants (Ki) for blood to brain permeation of [3H]sucrose measured from 30 min to 2 weeks postlesion showed sustained BBB leakiness; for example, mean Ki +/- SEM (nL.g(-1) x s(-1)) for a standard, matrix-dissected forebrain sample enclosing the lesion were 7.2 +/- 1.2 (day 1 postlesion), 8.1 +/-1.4 (day 3), 5.4 +/- 0.8 (day 14) compared with values for contralateral nonlesioned forebrain ranging from 1.3 +/- 0.05 to 1.6 +/- 0.3 (n = 3-4 samples per time point). Analysis of the simultaneous transport of [14C]sucrose (MW = 342 Da) and [3H]inulin (MW approximately 5,000) showed significantly larger upward increments in Ki for sucrose than inulin, indicating a pore-like opening mechanism. Significant edema was measured 3 days postlesion. A reactive glial response was indicated by an increase in S100beta by 6 h and a glial scar forming around the lesion by 7 days. Secondary brain injury was indicated by a 10% loss of hemisphere mass, measured at 2 months. The wire knife enabled tailoring of interstitial trauma with a minimum of extraneous injury and supported reproducible measurements of sustained BBB injury using relatively few animals.

Quantitative analysis of injured, necrotic, and apoptotic cells in a new experimental model of intracerebral hemorrhage

OBJECTIVE

To develop a new survival model of intracerebral hemorrhage (ICH) in rabbits and study the patterns of cellular injury in different regions 24 hrs after introduction of hematoma. Quantitation and characterization of injured cells in regions adjacent and distant to the hematoma have not been performed.

DESIGN

Prospective case-control study.

SUBJECTS

Ten New Zealand rabbits.

INTERVENTION

We introduced ICH in six anesthetized New Zealand rabbits by autologous blood injection under arterial pressure in the deep white matter in the frontal lobe.

MEASUREMENTS AND MAIN RESULTS

Hematoxylin and eosin staining was performed in six animals with ICH after 24 hrs to quantify intact, injured, and necrotic cells in regions proximal and distant to the hematoma, and the results were compared with four control animals. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining was performed to quantify apoptotic cells in specified regions in five animals with ICH, and the results were compared with four control animals. All cell counts were performed by one investigator who used 100x oil emersion microscopy. The presence of localized hematoma was confirmed in all six animals with blood infusion. Compared with controls, animals with ICH had a significantly higher proportion of swollen cells in both the inner (55.9% +/- 3.0% vs. 26.8% +/- 1.7%; p < .05) and the outer (59.8% +/- 4.6% vs. 27.7% +/- 4.5%; p < .05) rim of the perihematoma region. A small proportion of shrunken dark cells were observed in both the inner (4.0% +/- 1.5%) and the outer (3.6% +/- 1.0%) rim of the perihematoma region. The remaining cells were considered morphologically intact. A large proportion of cells trapped within the matrix of the hematoma were either shrunken dark cells (48.8% +/- 16.4%) or swollen (38.8% +/- 15.1%). In the TUNEL-stained sections, a high burden of apoptotic cells was observed in the matrix of the hematoma (17.5 +/- 6.3 cells per high power field) but not in the perihematoma regions (less than two cells per high power field).

CONCLUSIONS

A reproducible model of ICH in rabbits is described. At 24 hrs, the perihematoma region contains relatively large proportions of morphologically intact or reversibly injured (swollen) cells, suggesting the possibility of an extended window for therapeutic intervention.

Intracortical hemorrhage injury in rats : relationship between blood fractions and brain cell death

BACKGROUND AND PURPOSE

Intracerebral hemorrhage is associated with stroke and head trauma. The purposes of this study were to investigate the effect of intracortical injections of autologous whole blood and blood components on inflammatory cell infiltration and brain cell death and to determine if nonhemorrhagic lesions differ in these respects.

METHODS

Eighty-seven adult rats were subjected to intracortical injections of autologous whole blood or allogeneic plasma, erythrocytes, leukocytes, "activated" leukocytes, and serum. Injections of saline or mineral oil were controls. Blood injections were compared with cortical freeze injury and pial devascularization. Rats were perfusion-fixed 48 hours after injection or lesioning. Eosinophilic neurons, TUNEL-positive cells, brain damage area, infiltrating neutrophils, and CD8a-immunoreactive lymphocytes were quantified.

RESULTS

Damage area, dying cells, and inflammatory infiltrate were significantly greater after autologous whole blood, leukocyte, and "activated" leukocyte injections than injection of other fractions.

CONCLUSIONS

These results suggest that extravasated whole blood causes a greater degree of cortical cell death and inflammation than ischemic lesions of similar size. Leukocytes "activated" by systemic illness might exacerbate the injury. Secondary hemorrhagic phenomena suggest that the harmful effect is directed toward both brain cells and the vasculature. Further studies are required to delineate the mechanism(s).

Time window for clinical effectiveness of mass evacuation in a rat balloon model mimicking an intraparenchymatous hematoma

The purpose of this study is to evaluate in a rat model if the early removal of an experimental intracerebral mass mimicking an extensive subcortical hematoma improves neurological outcome. Fifty six male Wistar rats were studied. A balloon was placed sterotactically at the level of the striatum. The balloon was inflated to 100 microl for periods of 10, 60 or 120 min (with 10 animals in each group). In 10 animals the balloon was not deflated and there were four sham operated cases. Neurological deficit was evaluated by a blinded observer by means of a clinical scale from 0 to 8 points at 24 and 72 h after inflation. Three additional animals at each inflation period were sacrificed after 6 h for pathological study with hematoxylin-eosin staining. Death rate was 9/10 animals who had permanent inflation, 4/10 in those with 2 h inflation, 2/10 for 1 h inflation and 0/10 for 10 min inflation (P<0.01 in chi square test). Many animals developed a particular clinical syndrome not previously described. Mean 72 h clinical scores (0-8 points) were 7.6 (S.D.: 1. 2) for the permanent inflation group, 4.4 (S.D.: 3.2) for 2 h of inflation, 2.3 (S.D.: 3.2) for 1 h and 0.4 (0.9) for 10 min of inflation (P<0.01 in Kruskal Wallis test). In the pathological study the rate of damaged neurons was significantly higher in the permanent than in transient inflation groups. In conclusion, in this balloon model evacuation of an extensive acute expanding subcortical (hematoma-like) mass must be performed within a limited time window to prevent the development of irreversible neurological deficits or death.

Early alterations in cerebral hemodynamics, brain metabolism, and blood-brain barrier permeability in experimental intracerebral hemorrhage

OBJECT

The authors sought to ascertain the nature of the hemodynamic and metabolic derangement underlying acute pathophysiological events that occur after intracerebral hemorrhage (ICH).

METHODS

Cerebral perfusion pressure (CPP), flow velocity (FV) of the middle cerebral artery, and the arteriovenous contents of oxygen and lactate were investigated in 24 dogs subjected to sham operations (Group A, four animals) or intracerebral injections of 3 ml (Group B, 11 animals) or 5 ml (Group C, nine animals) autologous arterial blood. Twelve additional dogs received intravenous injections of 2% Evans blue or trypan blue dye to evaluate blood-brain barrier (BBB) changes. Within 1 hour, animals with ICH exhibited a rise in FV associated with significant reductions (p<0.05) in CPP and the arteriovenous content difference (AVDO2). In Group C animals significant increases in lactate concentration were found in arterial and superior sagittal sinus (SSS) samples compared with those in the other two groups (p<0.05). Additionally, perihematomal dye extravasation was observed in animals subjected to ICH and trypan blue dye injections, with profound and mild leakages in Group C and Group B animals, respectively, but not in Group A and Evans blue dye-injected animals. During the subsequent 4 hours, the FV and AVDO2 returned to normal in Group B animals, indicating a balanced cerebral metabolic rate for oxygen (CMRO2) compared with a deranged CMRO2 in Group C animals due to their lowered FV and AVDO2. However, no coupling increase in brain lactate clearance in Group C animals accounted for either the early lactate elevation in SSS or the decrease in CMRO2.

CONCLUSIONS

Profound reductions in CPP and brain oxygenation after ICH may rapidly exhaust hemodynamic compensation and, thus, impede cerebral homeostasis; however, these reductions only modestly enhance anaerobic glycolysis. Furthermore, the data suggest that a selective increase in permeability, rather than anatomical disruption, of the BBB is involved in the acute pathophysiological events that occur after ICH, which may provide a possible gateway for systemic arterial lactate entering the SSS.

ICP monitoring in the rat: comparison of monitoring in the ventricle, brain parenchyma, and cisterna magna

Various methods of continuous intracranial pressure (ICP) monitoring during experimental procedures in the rat have been described. However, no systematic comparison of ICP monitoring in the ventricle, brain parenchyma, and cisterna magna has been reported. Since accurate and reliable ICP measurements are important in experimental models of traumatic brain injury, the present study was conducted to compare simultaneous ICP measurements from ventricular, cisterna magna, and intraparenchymal monitors during ICP changes. Subdural hematoma was produced by infusion of 0.3 ml of autologous blood into the subdural space over 6 min. The ventricular and the intraparenchymal fiberoptic catheter produced reliable and comparable pressure recordings, that did not statistically differ (p = 0.4), throughout the one hour monitoring time. In contrast, the cisterna magna catheter was less reliable and produced significantly lower readings throughout the monitoring time (p<0.001). The intraparenchymal device produced greater cortical damage than the ventricular catheter. In conclusion, ventricular ICP monitoring is the preferred method under these circumstances, since it is accurate and induces least brain damage.

Progression of mass effect after intracerebral hemorrhage

BACKGROUND AND PURPOSE

While the evolution of mass effect after cerebral infarction is well characterized, similar data regarding intracerebral hemorrhage (ICH) are scant. Our goal was to determine the time course and cause for progression of mass effect after ICH.

METHODS

Patients with spontaneous supratentorial ICH who underwent >/=2 CT scans were identified in our prospectively collected database. CT lesion size and midline shift of the pineal and septum pellucidum were retrospectively measured and correlated with clinical and CT characteristics. Causes for increased midline shift were determined by 2 independent observers.

RESULTS

Seventy-six patients underwent 235 scans (3.1+/-1.3 per patient). Initial CT was obtained within 24 hours of ICH in 66. Twenty-five scans were repeated on day 1, 80 on days 2 through 7, 31 on days 8 through 14, and 24 >14 days after ICH. Midline shift was present on 88% of the initial scans. There were 17 instances of midline shift progression: 10 occurred early (0.2 to 1.7 days) and were associated with hematoma enlargement, and 7 occurred late (9 to 21 days) and were associated with edema progression. Progression of mass effect due to edema occurred with larger hemorrhages (P<0.05). Of 65 scans repeated for clinical deterioration, only 10 were associated with increased mass effect.

CONCLUSIONS

Progression of mass effect after ICH occurred at 2 distinct time points: within 2 days, associated with hematoma enlargement, and in the second and third weeks, associated with increase in edema. The clinical significance of later-developing edema is unclear.

Comparison of cerebral blood flow and injury following intracerebral and subdural hematoma in the rat

Subdural hematomas (SDH) can induce ischemia and neuronal damage in the underlying cortex. However, the extent to which intracerebral hematomas (ICH) produce reductions in cerebral blood flow (CBF) sufficient to cause ischemic damage is uncertain. Intracranial hemorrhage was induced by the injection of 100 or 200 microl of blood into the subdural space (SDH) or into the caudate nucleus (ICH) of the rat. CBF was measured using [14C]-iodoantipyrine autoradiography at 4 h. Brain damage was measured using 2,3, 5-triphenyl tetrazolium chloride (TTC) staining at 24 h and brain edema was measured using the wet/dry weight method. Brain ion contents were measured at 24 h using a flame photometer and chloridometer. In the CBF studies, the volume of tissue perfused below the ischemic threshold (<20 ml/100 g/min) for SDH was 122+/-35 mm3 (sham: 3.3+/-1.7 mm3). Following ICH, there was a small volume of tissue perfused below the ischemic threshold 50+/-11 mm3 (sham: 3. 3+/-2.5 mm3) but this volume corresponded closely to the volume of clot (71+/-5 mm3). The extent of brain damage, measured by TTC staining, in the cerebral cortex correlated with the increasing volume of the subdural blood clot (sham: 9+/-3 mm3; 200 microl: 81+/-19 mm3; P<0.01). Conversely, minimal brain damage was detected following ICH. The injection of blood into the subdural space or into the brain parenchyma induced blood volume-dependent increases in brain water content at 24 h. Increases in brain water content after SDH, were confined to the cerebral cortex (sham: 0.1+/-0.1 g/g dry weight; 200 microl: 0.8+/-0.3 g/g dry weight; P<0.001). In contrast, increases in brain water content after ICH were predominantly in the subcortical region (sham: 0.1+/-0.1 g/g dry weight; 200 microl: 0.4+/-0.2 g/g dry weight; P<0.01). The present investigations demonstrate differences in CBF, brain injury and edema formation following SDH and ICH indicating that these conditions may require different therapeutic interventions.

Treatment of elevated intracranial pressure in experimental intracerebral hemorrhage: comparison between mannitol and hypertonic saline

OBJECTIVE

Elevated intracranial pressure (ICP) is related to mortality after intracerebral hemorrhage (ICH). To develop effective strategies for the medical treatment of ICP in cases of ICH, we evaluated the therapeutic efficacy of mannitol and hypertonic saline in a canine model of ICH.

METHODS

We introduced ICH in three groups of anesthetized mongrel dogs, consisting of seven animals each, by autologous blood injection (5.5-7.5 ml) under arterial pressure in the deep white matter adjacent to the left basal ganglia. We evaluated the effect of iso-osmolar doses (5.5 mOsm/kg) of intravenously administered mannitol (1 gm/kg), 3% NaCl (5.3 ml/kg), or 23.4% NaCl (0.7 ml/kg) administered 2 hours after the introduction of hematoma, on the following: ICP, cerebral perfusion pressure, cerebral oxygen extraction and oxygen consumption, and regional cerebral blood flow in regions around and distant to the hematoma. All measurements were recorded at baseline, before treatment, and 15, 30, 60, and 120 minutes after treatment. We also evaluated the water content (wet/dry weight) and blood-brain barrier permeability (Evans blue method) in pathologically demarcated regions of brain.

RESULTS

There was an immediate reduction in ICP (mm Hg +/- standard error of the mean) in the 23.4% NaCl (27.6+/-4 to 11.0+/-2 mm Hg, P = 0.001), 3% NaCl (23.7+/-3 to 14.7+/-2 mm Hg, P = 0.009), and mannitol (25.6+/-3 to 15.9+/-4 mm Hg, P = 0.02) groups. Compared with pretreatment values, ICP was significantly lower in both the 23.4% NaCl (12.3+/-2 mm Hg, P = 0.002) and 3% NaCl (17.6+/-2 mm Hg, P = 0.008) groups but not in the mannitol group (18.7+/-4 mm Hg, P = 0.08) 15 minutes after the administration of treatment. There was a gradual rise in ICP observed in the 23.4% NaCl and mannitol groups with time. Only in the 3% NaCl group was the ICP significantly lower than the pretreatment value at 120 minutes (18.0+/-2 mm Hg, P = 0.02). A significantly higher cerebral perfusion pressure (108.4+/-4 versus 79.6+/-10 mm Hg, P = 0.048) and lower water content in the lesioned white matter (65.5+/-1% versus 67.9+/-1%, P = 0.07) was observed 2 hours after treatment in animals receiving 3% NaCl compared with animals receiving mannitol. There were no significant differences observed in regional cerebral blood flow, oxygen extraction, or oxygen consumption at any time point among the three groups.

CONCLUSION

Hypertonic saline, in both 3 and 23.4% concentrations, is as effective as mannitol in the treatment of intracranial hypertension observed in association with ICH. Hypertonic saline may have a longer duration of action, particularly when used in 3% solution. None of three treatment regimens influence regional cerebral blood flow or cerebral metabolism.

Temporal and spatial profile of apoptotic cell death in transient intracerebral mass lesion of the rat

Apoptosis is involved in the pathogenesis of cerebral ischemia. Previous studies have confirmed that the brain surrounding an intracerebral hematoma develops ischemia. We investigated the number and distribution of cells exhibiting DNA fragmentation with apoptotic morphology in the transient intracerebral mass lesion to determine whether apoptosis contributed to the lesion progress after intracerebral hemorrhage (ICH). Transient intracerebral mass was created by inflation of a microballoon for 10 min (group A) or 2 h (group B) in the caudoputamen in rats, and brains were examined 1, 3, 6, 24, and 48 h after microballoon deflation. The lesion volume was calculated using parallel coronal sections with cresyl violet staining. Terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine (dUTP)-biotin nick end labeling (TUNEL) was used to detect cells undergoing DNA fragmentation. Immunohistochemistry for Fas antigen was also done to ascertain molecular mechanisms of apoptosis. Histological examination of hematoxylin and eosin-stained sections showed the typical appearance of neuronal necrosis in the caudoputaminal lesion. Lesion volume in the caudoputamen gradually increased as time advanced from 1 to 48 h. Cells stained heavily by TUNEL with apoptotic morphology were detected in the lesion, but not in the inner boundary zone of the lesion. The number of these cells significantly increased from 6 to 24 h in each experimental group (p < 0.05). The cells with positive immunoreactivity for Fas antigen was prominently observed in the lesion at 6 h. The distribution of apoptotic cells and the rapid increase in the number of apoptotic cells after 24 h propose that apoptotic cell death may contribute to lesion core formation but not to gradual development of the lesion.

Erythrocytes and delayed brain edema formation following intracerebral hemorrhage in rats

OBJECT

The mechanisms of brain edema formation following spontaneous intracerebral hemorrhage (ICH) are not well understood. In previous studies, no significant edema formation has been found 24 hours after infusion of packed red blood cells (RBCs) into the brain of a rat or pig; however, there is evidence that hemoglobin can be neurotoxic. In this study, the authors reexamined the role of RBCs and hemoglobin in edema formation after ICH.

METHODS

The experiments involved infusion of whole blood, packed RBCs, lysed RBCs, rat hemoglobin, or thrombin into the right basal ganglia of Sprague-Dawley rats. The animals were killed at different time points and brain water and ion contents were measured. The results showed that lysed autologous erythrocytes, but not packed erythrocytes, produced marked brain edema 24 hours after infusion and that this edema formation could be mimicked by hemoglobin infusion. Although infusion of packed RBCs did not produce dramatic brain edema during the first 2 days, it did induce a marked increase in brain water content 3 days postinfusion. Edema formation following thrombin infusion peaked at 24 to 48 hours. This is earlier than the peak in edema formation that follows ICH, suggesting that there is a delayed, nonthrombin-mediated, edemogenic component of ICH.

CONCLUSIONS

These results demonstrate that RBCs play a potentially important role in delayed edema development after ICH and that RBC lysis and hemoglobin toxicity may be useful targets for therapeutic intervention.

Increase in the chronically monitored cerebrospinal fluid pressure after experimental brain injury in rats

The early effects of experimental brain injury with diffuse axonal lesions on intracranial pressure (i.c.p.), mean arterial pressure (MAP) and cerebral perfusion pressure (CPP) in rats have been already studied. The aim of this experiment was to examine the effects of brain injury on ICP, MAP and CPP during the first few days post-injury. In order to do that, an accurate technique of ICP measurement had to be developed. In a series of eight rats, a translumbar intrathecal catheter (TIC) was surgically introduced allowing repeated measurements of cerebrospinal fluid pressure (CSFP). Under anaesthesia, a second series of nine rats were equipped simultaneously with TIC and an intracranial fiberoptic device to measure ICP. Simultaneous measurements of CSFP and ICP were recorded for baseline values, than during and after jugular compression which was intended to induce an acute and significant increase in ICP. A third series of 53 rats having TIC received an experimental severe brain injury. MAP was measured non-invasively and CPP was calculated as CPP-MAP. CSFP, MAP and CPP were intermittently measured during 5-6 post-traumatic days and compared to the values obtained during ten control rats (SHAM). A clinical score was used to compare clinical condition. The results showed that the translumbar CSFP accurately measured ICP in rats having normal or acutely increased ICP. The experimental brain injury induced increased CSFP lasting up to 5-6 days, with increased MAP during the first 6 hours. CPP values were compromised at 24-48 hours. The clinical performance was reduced in the brain-injured rats. The translumbar technique of CSFP measurement reflected exact ICP in normal and acutely increased ICP in rats. Experimental brain injury with diffuse axonal lesions can increase lumbar CSFP in rats for many days.

Evaluation of cerebral vasospasm after early surgical and endovascular treatment of ruptured intracranial aneurysms

OBJECTIVE

To document the influence of the treatment modality (early surgery versus early endovascular treatment) on measures of cerebral vasospasm in a nonrandomized series of 156 patients treated within 72 hours of aneurysmal subarachnoid hemorrhage.

METHODS

The following parameters were prospectively collected in a computerized data base and retrospectively analyzed for association with vasospasm-related ischemic infarctions: 1) Hunt and Hess (H&H) grade, 2) Fisher grade, 3) highest mean cerebral blood flow velocity (CBFVMAX) and maximum percent change in mean CBFV (%deltaCBFV) as recorded by transcranial Doppler ultrasound, 4) incidence of repeat subarachnoid hemorrhage, 5) incidence of delayed ischemic neurological deficits, 6) incidence of delayed ischemic infarctions, and 7) Glasgow Outcome Scale score.

RESULTS

Forty-one patients (26.3%) suffered ischemic infarctions. The ischemic infarction rate was correlated with higher H&H grade (P = 0.002), higher Fisher grade (P = 0.05), higher CBFVMAX (P < 0.001) and %deltaCBFV (P = 0.01), occurrence of repeat subarachnoid hemorrhage, occurrence of delayed ischemic neurological deficits, and endovascular treatment (P = 0.02).

CONCLUSION

The infarction rate was higher with endovascular treatment versus surgery (37.7 versus 21.6%), as a result of a skewed Fisher Grade 4 infarction pattern in the endovascular treatment group versus the surgery treatment group (66.7 versus 24.5%). We suspect that unremoved subarachnoid/intracerebral clots contributed to the higher infarction rate with endovascular treatment. When patients with Fisher Grade 4 and H&H Grade V were excluded from analysis, the difference in infarct incidence between the treatment groups no longer reached statistical significance (Fisher Grades 1-3, P = 0.49; H&H Grades I-IV, P = 0.96).

A chronic model to simultaneously measure intracranial pressure, cerebral blood flow, and study the pial microvasculature

In an effort to study changes in cerebral blood flow (CBF), intracranial pressure (ICP) and intracranial compliance (ICC) simultaneously, we have developed a chronic model in rats using a pial window crown with two ports. This model can also be used to study vasoreactivity of pial vessels. Female Sprague-Dawley rats weighing between 225-250 g underwent placement of cranial chamber with dual ports under pentobarbital anesthesia. To test the utility of this technique 45 groups of rats were studied. Group 1 consisted of control animals. Group 2 consisted of rats undergoing 15 min of global cerebral ischemia. Rats in group 3 were evaluated for changes in vessel diameter and ICP after adenosine injection. In group 4 leukocyte/endothelial interactions were evaluated. These groups demonstrate the ability of this model to monitor CBF, ICP, ICC and pial vessel architecture in chronic rat experiments.

Mechanisms of edema formation after intracerebral hemorrhage: effects of thrombin on cerebral blood flow, blood-brain barrier permeability, and cell survival in a rat model

Recently, the authors showed that thrombin contributes to the formation of brain edema following intracerebral hemorrhage. The current study examines whether the action of thrombin is due to an effect on cerebral blood flow (CBF), vasoreactivity, blood-brain barrier (BBB) function, or cell viability. In vivo solutions of thrombin were infused stereotactically into the right basal ganglia of rats. The animals were sacrificed 24 hours later; CBF and BBB permeability were measured. The actions of thrombin on vasoreactivity were examined in vitro by superfusing thrombin on cortical brain slices while monitoring microvessel diameter with videomicroscopy. In separate experiments C6 glioma cells were exposed to various concentrations of thrombin, and lactate dehydrogenase release, a marker of cell death, was measured. The results indicate that thrombin induces BBB disruption as well as death of parenchymal cells, whereas CBF and vasoreactivity are not altered. The authors conclude that cell toxicity and BBB disruption by thrombin are triggering mechanisms for the edema formation that follows intracerebral hemorrhage.

Heme oxygenase-1 and heat shock protein 70 induction in glia and neurons throughout rat brain after experimental intracerebral hemorrhage

OBJECTIVE

Current experimental evidence demonstrates the development of ischemic regions adjacent to and spatially remote from an intracerebral hematoma. The cause of this ischemia is uncertain. Because ischemia is a known inducer of stress genes, we investigated the induction of two stress proteins, heme oxygenase (HO)-1 and heat shock protein (Hsp) 70, after intracerebral hemorrhage in the rat.

METHODS

Immunocytochemistry for HO-1, Hsp70, and HO-2, the constitutive isoform of the HO enzyme, was performed 1, 2, and 4 days after striatal injection of saline, whole blood, or lysed blood. Immunocytochemistry for HO-1, HO-2, and Hsp70 was also performed 1 day after cortical injection of saline, whole blood, or lysed blood.

RESULTS

After striatal injection of lysed and whole blood, the HO-1 protein was induced in glia throughout the hemisphere ipsilateral to the hematoma, and HO-1 immunoreactivity persisted for at least 4 days. After cortical injection of lysed and whole blood, HO-1 was induced in glia throughout the neocortex. Neuronal induction of HO-1 was also observed after cortical injection of lysed blood but not whole blood or saline. After striatal injection of lysed blood, Hsp70 was induced in glia surrounding the hematoma and in neurons from the neocortex overlying the hematoma and the striatum adjacent to the hematoma. After cortical injection of lysed blood, Hsp70 was induced in neurons throughout the neocortex and hippocampus bilaterally. In contrast, after whole blood and saline injection into cortex, Hsp70 induction was observed only in scattered neurons surrounding the hematoma cavity.

CONCLUSION

Our results demonstrate that blood in the brain parenchyma induces the HO-1 stress protein but does not significantly alter HO-2 immunostaining. Our results also demonstrate that lysed blood induces Hsp70 in multiple regions of the brain and that the stress response of the brain differs depending on whether lysed blood is injected into the cortex or striatum. These results suggest that blood lysis may play an unforeseen role in the stress response of the brain to intracerebral hemorrhage.

Management of hypertension in acute intracerebral hemorrhage

Hypertension commonly occurs in the acute period following spontaneous intracerebral hemorrhage. Management of this hypertension is controversial. Some advocate lowering blood pressure to reduce the risk of bleeding, edema formation, and systemic hypertensive complications, whereas others advocate allowing blood pressure to run its natural course as a protective measure against cerebral ischemia. This article reviews the pertinent clinical and experimental data regarding these issues and briefly discusses the use of antihypertensive agents commonly administered in this setting.

Mechanisms of edema formation after intracerebral hemorrhage: effects of thrombin on cerebral blood flow, blood-brain barrier permeability, and cell survival in a rat model

Recently, the authors showed that thrombin contributes to the formation of brain edema following intracerebral hemorrhage. The current study examines whether the action of thrombin is due to an effect on cerebral blood flow (CBF), vasoreactivity, blood-brain barrier (BBB) function, or cell viability. In vivo solutions of thrombin were infused stereotactically into the right basal ganglia of rats. The animals were sacrificed 24 hours later; CBF and BBB permeability were measured. The actions of thrombin on vasoreactivity were examined in vitro by superfusing thrombin on cortical brain slices while monitoring microvessel diameter with videomicroscopy. In separate experiments C6 glioma cells were exposed to various concentrations of thrombin and lactate dehydrogenase release, a marker of cell death, was measured. The results indicate that thrombin induces BBB disruption as well as death of parenchymal cells, whereas CBF and vasoreactivity are not altered. The authors conclude that cell toxicity and BBB disruption by thrombin are triggering mechanisms for the edema formation that follows intracerebral hemorrhage.

Hemodynamics of hypertensive putaminal hemorrhage evaluated by Xenon-enhanced computed tomography and acetazolamide test

Cerebral blood flow (CBF) is usually decreased in patients with hypertensive putaminal hemorrhage (HPH). However, there are few reports concerning cerebrovascular reserve capacity (CRC) in these cases. This study evaluated cerebral hemodynamics in patients with HPH by measuring CBF and CRC. CBF and CRC were measured by stable xenon enhanced computed tomography (Xe-CT) in 11 patients with HPH (HPH group) and 11 patients with essential hypertension without intracerebral hematoma (non-HPH group). CBFs of the hemisphere and thalamus in the HPH group were lower than those in the non-HPH group. And the CBF of the hemisphere was increased transiently after the surgical evacuation of the hematoma. Thereafter, it fell gradually. The CRCs were also lower in acute stage of the HPH group. The CRC recovered during the chronic stage. Hemodynamics in patients with HPH can be modulated by surgical removal of hematoma. However, some adjunct therapies are necessary to prevent delayed neuronal inactivity, Stable Xe-CT with acetazolamide test is useful to evaluate hemodynamics in the HPH patients.

Application of transcranial Doppler sonography in surgical aspects of hypertensive putaminal haemorrhage

From May 1992 to February 1993, 22 cases of hypertensive putaminal haemorrhage (HPH) treated at our hospital were serially measured with transcranial Doppler (TCD) sonography. Among them, 13 patients underwent surgical intervention (3 stereotaxic surgery and 10 craniotomies), and 9 were conservatively treated. Most of the patients of the two operative groups had larger haematomas and developed clinical and/or neurological deterioration, which was the indication for subsequent surgery. Therefore the groups represent different clinical and physiological entities. On admission, the peak MCA velocities (Vs) in the surgical group (stereotaxic and craniotomy) were significantly lower than those in the conservative group (mean +/- S.E.M.: 38.33 +/- 4.26 and 42.00 +/- 2.62 cm/sec vs. 57.22 +/- 3.23 cm/sec; p < 0.005, respectively). The surgical group also had significantly lower diastolic (Vd) and mean (Vm) velocities than those of the conservative group (p < 0.001). Rather, the admission pulsatility indices (PI = (Vs-Vd)/Vm) in the surgical group were significantly higher than those of the conservative group (mean +/- S.E.M.: 1.42 +/- 0.04 and 1.31 +/- 0.09 vs. 0.95 +/- 0.01; p < 0.005, respectively). Time course velocity curves reached a peak around the 3rd hospital day in all the 3 groups. The Glasgow coma scale (GCS) scores positively correlated with the mean MCA velocities (n = 22; r = 0.63, p < 0.005; y = 2.04 x + 8.74), but negatively with PI values on admission (n = 22; r = -0.53, p < 0.05; y = 1.68-0.053 x). On the 7th hospital day, 2 patients with peak MCA velocities below 50 cm/sec had an unfavourable outcome. All the 3 patients in the stereotaxic group had higher peripheral resistance, as compared with those in conservative craniotomy groups (mean +/- S.E.M.: 1.28 +/- 0.13 vs. 0.99 +/- 0.07 and 0.87 +/- 0.06; p < 0.05, respectively). Our study supports TCD as a safe and valid monitoring method in patients with HPH. "Compromised cerebral haemodynamic status" (Vs < 50 cm/sec, Vd < 15 cm/sec, Vm < 25 cm/sec, PI > 1.15) may offer an aid in the decision for surgical intervention in HPH. Postoperatively, patients who made a favourable recovery had a significant increment in the MCA velocities in contrast to those severely disabled, whose MCA velocities remained low.

Experimental intracerebral hemorrhage: relationship between brain edema, blood flow, and blood-brain barrier permeability in rats

There have been few investigations of brain edema formation after intracerebral hemorrhage (ICH), despite the fact that mass effect and edema are important clinical complications. The present study was designed to investigate the time course for the formation and resolution of brain edema and to determine how changes in cerebral blood flow (CBF) and blood-brain barrier (BBB) permeability are temporally related to edema formation following ICH. Anesthetized adult rats received a sterile injection of 100 microliters of autologous blood into the caudate nucleus. Water and ion contents were measured immediately, at 4 and 12 hours, and daily to Day 7 (10 time points, six rats at each time) after experimental ICH. The water content of the ipsilateral basal ganglia increased progressively (p < 0.002) over the first 24 hours, then remained constant until after Day 5, when the edema began to resolve. Edema was most severe in the tissue immediately surrounding the hemorrhage; however, it was also present in the ipsilateral cortex, the contralateral cortex, and the basal ganglia. Measurements of local CBF (using [14C]-iodoantipyrine) and BBB permeability (using [3H]-alpha-aminoisobutyric acid) were obtained in separate groups of six to eight rats at various time intervals between 1 and 48 hours after ICH. Cerebral blood flow was reduced to 50% of control at 1 hour, returned to control values by 4 hours, but then decreased to less than 50% of control between 24 and 48 hours after ICH. The BBB permeability increased significantly prior to the occurrence of significant edema in the tissue surrounding the clot. However, BBB permeability in the more distant structures remained normal despite the development of edema. These results demonstrate a time course for the formation and resolution of brain edema following ICH similar to that observed during focal ischemia. Brain edema forms in the immediate vicinity of the clot as a result of both BBB disruption and the local generation of osmotically active substances and then spreads to adjacent structures. While local ischemia, due to the mass effect of the hemorrhage, may play a role in producing cytotoxic and vasogenic edema, the release of toxic substances from the clot should also be considered. Since edema is nearly maximal by 24 hours after ICH, therapy directed at reducing edema formation must be instituted within the 1st day.

Infratentorial ischaemia following experimental cerebellar haemorrhage in the rat

Early changes of cerebellar and cerebral blood flow, as well as subsequent infratentorial ischaemia, were evaluated in an experimental model of cerebellar haemorrhage. Eight anaesthetized male adult Sprague-Dawley rats received an injection of autologous arterial blood (50 microliters) into the right cerebellar hemisphere. Eight animals were sham-operated and served as controls. Cerebellar blood flow, measured at regular time intervals in the hemispheric cortex ipsilateral to the lesion by the hydrogen clearance method, was significantly depressed in the experimental group as compared with the control animals. This drop in cerebellar blood flow was evident 5, 30, 60, 90, and 120 min postoperatively, with a return to pre-injection values recorded 180 min after surgery. No significant difference in supratentorial blood flow was detected over the entire period examined between the two groups of animals. Enzyme histochemistry demonstrated areas of ischaemia around the clot and within the brain stem in animals with an intracerebellar haemorrhage at the end of the experiment. These results provided evidence of ischaemic damage within the infratentorial compartment after the induction of experimental cerebellar haemorrhage.

The effects of blood or plasma clot on brain edema in the rat with intracerebral hemorrhage

The causes and characteristics of the brain edema which forms adjacent to an acute intracerebral hemorrhage (ICH) have not been explored thoroughly. This study was designed to examine the edema process in rat brain provoked by two different blood clot components. An intracerebral clot was produced by stereotactic injection of 100 microl of either blood (bICH) or cryoprecipitate/thrombin (pICH) into the right caudate nucleus. Water, Na+, K+, and Cl- contents were measured at 0, 4.24, 48, and 72 h after instillation of the clot. During the first 24 h, the water content of the ipsilateral caudate nucleus and cortex gradually increased in both groups. By 48 h brain edema was more severe in the bICH compared to that with pICH in the ipsilateral basal ganglia and cortex. The edema formation was accompanied by significant increase in sodium and chloride, as well as a decrease in potassium content by 48 h and sustained to 72 h. These results suggest that both blood and plasma clots can cause brain edema, but a plasma clot is less damaging than a blood clot in the immediate vicinity of the mass.

The effect of immunosuppression on the development of cerebral oedema in an experimental model of intracerebral haemorrhage: whole body and regional irradiation

The oedema which forms around an intracerebral haemorrhage has a complex aetiology. The immune response may have a role in its formation. There is clinical and experimental evidence that circulating leucocytes and platelets may mediate oedema formation. Global depletion of circulating leucocytes and platelets by whole body irradiation in a rodent model of intracerebral haemorrhage was found to confer protection against both ischaemia and oedema formation. This was not a direct effect of irradiation of the brain. The possible mechanisms for this protection are discussed.

A simple and reliable technique to monitor intracranial pressure in the rat: technical note

A technique for intracranial pressure (ICP) monitoring in the rat that uses a permanent cisterna magna cannula is described. The cannula is placed into the subarachnoid space through the atlanto-occipital membrane with the operating microscope and is secured with cement. The distal end is connected to a pressure transducer and a polygraph recorder. To study the consistency of this technique, 12 anesthetized adult rats were subjected to baseline ICP measurements 2 days after placement of the cannula. Baseline pressures ranged between 1.0 and 10.0 cm H2O, with a mean of 5.6 cm H2O. Respiratory variations were detected in all tracings, and manual abdominal compressions (Valsalva maneuver) correlated with immediate transient rises in ICP in all rats. While CSF pressure was being continuously monitored, rats were subjected to subarachnoid hemorrhage induced by transclival basilar artery puncture. Of the 12 rats, 10 showed a moderate transient rise in cerebrospinal fluid pressure, which peaked approximately 2 minutes after subarachnoid hemorrhage (mean peak change, 10.5 cm H2O; range, 0-32.5 cm H2O). Reliable pressure tracings were obtained in three of five animals examined 3 days after subarachnoid hemorrhage (ICP range, 4.0-4.5 cm H2O; mean, 4.2 cm H2O). We conclude that this cannula is easy and inexpensive to construct and that it provides reliable ICP tracings during experimental procedures in the rat.

Experimental intracerebral haemorrhage in normotensive and spontaneously hypertensive rats

Early changes in intracranial pressure (ICP) and mean arterial blood pressure (MABP) were studied in normotensive and spontaneously hypertensive (SHR) Wistar rats after the development of an experimental intracerebral haemorrhage (ICH). The volume of the ICH was 200 or 400 microliters and they were located in the nucleus caudatus or the subcortical area of the occipital lobe. Our study shows that 200 microliters ICH produced both in normotensive and SHR rats similar mortality rates and ICP changes. However, 400 microliters ICH lead to a significantly higher mortality in SHR rats. The systemic hypertensive response to the increasing of ICP was not observed in SHR animals. Thus, the increase in the cerebral pressure perfusion measured in normal rats does not happen in SHR rats. The cause of this fact in SHR rats could be due to local factors or related to alterations in the peripheral part of the vasomotor reflex.

Ultra-early evaluation of intracerebral hemorrhage

The authors evaluate eight patients with intracerebral hemorrhage (ICH) who underwent computerized tomography (CT) within 2 1/2 hours after symptom onset and then again several hours later. The second CT scan was performed within 12 hours after onset for seven of the patients and 100 hours after onset for the eighth patient. In four patients, the second CT scan was obtained prospectively. The mean percentage of increase in the volume of hemorrhage between the first and second CT scans was 107% (range 1% to 338%). In each of the six patients with a greater than 40% increase in hemorrhage volume, neurological deterioration occurred soon after the first CT. A systolic blood pressure of 195 mm Hg or greater was recorded during the first 6 hours in five of the same six patients. The data from this study indicate that, in ICH, bleeding may continue after the 1st hour post-hemorrhage, particularly in patients with early clinical deterioration.

Experimental intracerebral haematoma: the role of blood constituents in early ischaemia

In patients with intracerebral haematoma, ischaemic damage and final outcome are often more serious than the size of the lesion would suggest. The aetiology of the ischaemia in relation to space-occupying effects or specific factors present in blood is unclear. In a rat model of an intracerebral space-occupying lesion, the pathophysiological effects of a haematoma were compared with those of an equal volume of inert fluid (mock cerebrospinal fluid [CSF] or silicone oil). Cerebral blood flow was measured at 1 min by 14C iodoantipyrine autoradiography, and ischaemic cell damage was assessed by light microscopy at 4 h. In all animals, cerebral blood flow was reduced immediately adjacent to the lesion. In the group with a haematoma, blood flow was reduced (p less than 0.001) over a greater radius and also in the ipsilateral frontal and parietal cortex. Ischaemic damage was seen in animals lesioned with blood or oil of blood viscosity, but not in animals with CSF lesions. These data suggest that both tissue pressure and vasoactive substances are components of the immediate reduction in blood flow following intracranial haemorrhage. Tissue pressure may be the more important factor in later ischaemic neuronal damage.

Experimental intracerebral haematoma in the rat: sequential light microscopical changes

In a small animal model of controlled intracerebral haemorrhage, changes within the haematoma and surrounding tissues were examined by light microscopy in toluidine blue stained semithin sections. Groups of animals were killed at 2, 6, 15, 24 and 48 hours, 2, 4, 8 and 14 days, and 3 months survival. Sequential changes in neurons, glia and leucocytes, together with the gradual absorption of the blood clot and its replacement by an astrocytic scar are described.

Favourable effect of flunarizine on the recovery from hemiparesis in rats with intracerebral hematomas

In 25 rats, an intracerebral hematoma was created in the foreleg area of the motor cortex by injection of 50 microliters blood. After the lesion, 13 were treated with flunarizine and 12 with the solvent. Neurological testing was performed by measuring the running time on a rotating platform. In animals with hemiparesis, the flunarizine group (n = 7) showed a significantly (P less than 0.05) better recovery than the control group (n = 8). No significant differences occurred in animals without neurological deficits (flunarizine: n = 6, control: n = 4). So the effect of the drug is not due to a non-specific activation; it may partially cure neurological deficits caused by intracerebral hematoma.

Endoscopic surgery versus medical treatment for spontaneous intracerebral hematoma: a randomized study

A controlled randomized study of endoscopic evacuation versus medical treatment was performed in 100 patients with spontaneous supratentorial intracerebral (subcortical, putaminal, and thalamic) hematomas. Patients with aneurysms, arteriovenous malformations, brain tumors, or head injuries were excluded. Criteria for inclusion were as follows: patients' age between 30 and 80 years; a hematoma volume of more than 10 cu cm; the presence of neurological or consciousness impairment; the appropriateness of surgery from a medical and anesthesiological point of view; and the initiation of treatment within 48 hours after hemorrhage. The criteria of randomization were the location, size, and side of the hematoma as well as the patient's age, state of consciousness, and history of hypertension. Evaluation of outcome was performed 6 months after hemorrhage. Surgical patients with subcortical hematomas showed a significantly lower mortality rate (30%) than their medically treated counterparts (70%, p less than 0.05). Moreover, 40% of these patients had a good outcome with no or only a minimal deficit versus 25% in the medically treated group; the difference was statistically significant for operated patients with no postoperative deficit (p less than 0.01). Surgical patients with hematomas smaller than 50 cu cm made a significantly better functional recovery than did patients of the medically treated group, but had a comparable mortality rate. By contrast, patients with larger hematomas showed significantly lower mortality rates after operation but had no better functional recovery than the medically treated group. This effect from surgery was limited to patients in a preoperatively alert or somnolent state; stuporous or comatose patients had no better outcome after surgery. The outcome of surgical patients with putaminal or thalamic hemorrhage was no better than for those with medical treatment; however, there was a trend toward better quality of survival and chance of survival in the operated group.