Effect of intracerebral and subdural hematomas on energy-dependent transport across the blood-brain barrier

Blood-brain barrier function in intracerebral hemorrhage

In this paper, we review current knowledge on blood-brain barrier (BBB) dysfunction following intracerebral hemorrhage (ICH). BBB disruption is a hallmark of ICH-induced brain injury. Such disruption contributes to edema formation, the influx of leukocytes, and the entry of potentially neuroactive agents into the perihematomal brain, all of which may contribute to brain injury. A range of factors have been implicated in inducing BBB disruption, including inflammatory mediators (e.g., cytokines and chemokines), thrombin, hemoglobin breakdown products, oxidative stress, complement, and matrix metalloproteinases. While there is interaction between some of these mediators, it is probable that prevention of ICH-induced BBB disruption will involve blocking multiple pathways or blocking a common end pathway (e.g., by stabilizing tight junction structure). While the effects of ICH on BBB passive permeability have been extensively examined, effects on other 'barrier' properties (metabolic and transport functions) have been less well-studied. However, recent data suggests that ICH can affect transport and that this may help protect the BBB and the brain. Indeed, it is possible in small bleeds that BBB disruption may be beneficial, and it is only in the presence of larger bleeds that disruption has detrimental effects.

Caspase-dependent cell death involved in brain damage after acute subdural hematoma in rats

Traumatic brain injury is associated with acute subdural hematoma (ASDH) that worsens outcome. Although early removal of blood can reduce mortality, patients still die or remain disabled after surgery and additional treatments are needed. The blood mass and extravasated blood induce pathomechanisms such as high intracranial pressure (ICP), ischemia, apoptosis and inflammation which lead to acute as well as delayed cell death. Only little is known about the basis of delayed cell death in this type of injury. Thus, the purpose of the study was to investigate to which extent caspase-dependent intracellular processes are involved in the lesion development after ASDH in rats. A volume of 300microL blood was infused into the subdural space under monitoring of ICP and tissue oxygen concentration. To asses delayed cell death mechanisms, DNA fragmentation was measured 1, 2, 4 and 7 days after ASDH by TUNEL staining, and the effect of the pan-caspase inhibitor zVADfmk on lesion volume was assessed 7 days post-ASDH. A peak of TUNEL-positive cells was found in the injured cortex at day 2 after blood infusion (53.4+/-11.6 cells/mm(2)). zVADfmk (160ng), applied by intracerebroventricular injection before ASDH, reduced lesion volume significantly by more than 50% (vehicle: 23.79+/-7.62mm(3); zVADfmk: 9.06+/-4.08). The data show for the first time that apoptotic processes are evident following ASDH and that caspase-dependent mechanisms play a crucial role in the lesion development caused by the blood effect on brain tissue.

Chemical shift imaging of mannitol in acute cerebral ischemia. Case report

The effectiveness of mannitol for the treatment of cerebral edema after stroke has long been debated, and the diffusion of mannitol through a disrupted blood-brain barrier has been the focus of many contradictory studies. The authors present a unique case in which chemical shift imaging was used to demonstrate the accumulation of mannitol in an area of stroke underlying a subdural hematoma in a patient with end-stage renal disease being treated with hemodialysis. A metabolite map for the xenobiotic mannitol was created from the data and demonstrated the accumulation of mannitol when hemodialysis was interrupted prematurely. Metabolite maps were also used to show removal of the mannitol with the reestablishment of hemodialysis. It is concluded that mannitol can accumulate in an area of infarction, and that chemical shift imaging can be used to illustrate this process.

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.