Further evidence for a continuous flux of bile acids into the brain: trapping of bile acids in subdural hematomas.

Bile acids are known to pass the blood-brain barrier and are present at low concentrations in the brain. In a previous work, it was shown that subdural hematomas are enriched with bile acids and that the levels in such hematomas are higher than in the peripheral circulation. The mechanism behind this enrichment was never elucidated. Bile acids have a high affinity to albumin, and subdural hematomas contain almost as high albumin levels as the peripheral circulation. A subdural hematoma is encapsulated by fibrin which may allow passage of small molecules like bile acids. We hypothesized that bile acids originating from the circulation may be 'trapped' in the albumin in subdural hematomas. In the present work, we measured the conjugated and unconjugated primary bile acids cholic acid and chenodeoxycholic acid in subdural hematomas and in peripheral circulation of 24 patients. In most patients, the levels of both conjugated and free bile acids were higher in the hematomas than in the circulation, but the enrichment of unconjugated bile acids was markedly higher than that of conjugated bile acids. In patients with a known time interval between the primary bleeding and the operation, there was a correlation between this time period and the accumulation of bile acids. This relation was most obvious for unconjugated bile acids. The results are consistent with a continuous flux of bile acids, in particular unconjugated bile acids, across the blood-brain barrier. We discuss the possible physiological importance of bile acid accumulation in subdural hematomas.

Subdural haematomas drain into the extracranial lymphatic system through the meningeal lymphatic vessels.

Subdural haematomas (SDHs) are characterized by rapidly or gradually accumulated haematomas between the arachnoid and dura mater. The mechanism of haematoma clearance has not been clearly elucidated until now. The meningeal lymphatic vessel (mLV) drainage pathway is a novel system that takes part in the clearance of waste products in the central nervous system (CNS). This study aimed to explore the roles of the mLV drainage pathway in SDH clearance and its impacting factors. We injected FITC-500D, A488-fibrinogen and autologous blood into the subdural space of mice/rats and found that these substances drained into deep cervical lymph nodes (dCLNs). FITC-500D was also observed in the lymphatic vessels (LYVE+) of the meninges and the dCLNs in mice. The SDH clearance rate in SDH rats that received deep cervical lymph vessel (dCLV) ligation surgery was significantly lower than that in the control group, as evaluated by haemoglobin quantification and MRI scanning. The drainage rate of mLVs was significantly slower after the SDH model was established, and the expression of lymphangiogenesis-related proteins, including LYVE1, FOXC2 and VEGF-C, in meninges was downregulated. In summary, our findings proved that SDH was absorbed through the mLV drainage pathway and that haematomas could inhibit the function of mLVs.

Retroocular and Subdural Hemorrhage or Hemosiderin Deposits in Pediatric Autopsies.

The presence of hemosiderin in the optic nerve sheath and/or retina is sometimes used to estimate the timing of injury in infants or children with suspected non-accidental head trauma. To determine the prevalence of hemosiderin in deaths not associated with trauma, we performed a prospective study of retroocular orbital tissue, cranial convexity, and cervical spinal cord dura mater in infants and children <2.5 years age. In 53 cases of non-traumatic death, approximately 70% had blood or hemosiderin within the orbital fat, ocular muscles, and parasagittal cranial and/or cervical spinal subdural compartment. This bleeding is likely a consequence of the birth process. None had evidence of hemorrhage within the optic nerve sheath. Premature birth was less likely associated with orbital tissue hemorrhage. Caesarean section birth (mainly nonelective) was not associated with lower prevalence. Residual hemosiderin was identifiable up to 36 weeks postnatal age, suggesting gradual disappearance after birth. Cardiopulmonary resuscitation (performed in the majority of cases) was not associated with acute hemorrhage. In 9 traumatic deaths, 6 had blood and/or hemosiderin within the optic nerve sheath. Knowledge of the potential presence and resolution of hemosiderin in these locations is important for medicolegal interpretation of childhood deaths associated with head or brain injury.

Fatal hemorrhage due to a spontaneous factor V inhibitor with lupus anticoagulant properties.

: Factor V inhibitors are rare and have varied clinical presentations. We report on a 76-year-old female admitted to the hospital for pneumonia and treated with multiple antibiotics. Her baseline prothrombin time was 15.6 s and the activated partial thromboplastin time was 35 s. On admission day 10, she developed arm weakness and brain imaging showed a subdural hematoma. The prothrombin time was now 59.1 s with an activated partial thromboplastin time of more than 160 s and a normal thrombin time. A mixing study did not correct the clotting times and coagulation factor assays showed a nonspecific inhibition pattern. Only factor V activity remained low with serial dilutions, however, and a 70 Bethesda Unit inhibitor was identified. Aggressive supportive care was initiated but the patient succumbed to the effects of the intracranial hemorrhage. Factor V inhibitors may display lupus anticoagulant properties and may cause catastrophic bleeding. Our case illustrates that these inhibitors can arise quickly and supports an association with antibiotics.

Intracranial venous injury, thrombosis and repair as hallmarks of mild blast traumatic brain injury in rats: Lessons from histological and immunohistochemical studies of decalcified sectioned heads and correlative microarray analysis.

BACKGROUND: Many previous experimental studies of blast wave effects have reported vascular and parenchymal injury in brains extracted from the skulls prior to histopathological assessment. Brain removal disrupts vasculature and structural features of the meninges that may be sources of signs and symptoms of mild traumatic brain injury, particular at lower blast overpressures (<5psi peak). NEW METHOD: Immunohistochemical and histopathological studies have been conducted in sections from decalcified, paraffin embedded, histologically sectioned whole rat heads. These sections preserve the entire cranial contents in situ, and permit evaluation of the inner ear, central nervous system and associated vasculature. The findings could also be correlated with mRNA expression patterns from whole brains subjected to similar treatment. RESULTS: Lower levels of blast wave exposure produce primarily vascular effects in rats. Messenger RNA profiles of the whole brains showed evidence of both blast intensity and time dependent effects on vascular wound healing markers. The rats exposed to 10-11psi overpressure tended to show a similar pattern of mRNA expression changes in these vascular repair and inflammatory pathways as rats exposed to approximately 5psi overpressure, but the changes were greater. The changes in mRNA expression after a 14-15psi exposure were different and suggestive of more severe injury, particularly for DNA repair, lymphocyte activation and lymphocyte migration pathways. Histopathological examination of decalcified heads revealed that even 2.5-7.9psi blast exposures produced a high prevalence of mild venous hemorrhage and thrombosis (accompanied by inflammatory markers) in the inner ear, vertebrobasilar circulation, hippocampal choroidal fissure and the veins associated with velum interpositum. COMPARISON WITH EXISTING METHOD(S): The sites of vascular injury would not have been included in specimens extracted from the skull prior to processing. CONCLUSIONS: The isolated regions of intravascular coagulation in small veins and the isolated, very small venous hemorrhages in the subarachnoid space are worthy of consideration as factors in both healing and chronic sequelae of mild blast concussion. Although small, remnants persisted in the subarachnoid space even 42 days after a single blast exposure. The high prevalence of very mild subdural and subarachnoid hemorrhage may be a target for clinical management.

Development of chronic encapsulated intracerebral hematoma after radiosurgery for a cerebral arteriovenous malformation.

BACKGROUND: We report a rare case of chronic encapsulated intracerebral hematoma (CEIH) after radiosurgery for a cerebral arteriovenous malformation (AVM). METHODS: Seven years after radiosurgery, magnetic resonance imaging revealed a high-intensity mass in the right basal ganglia with a peripheral low signal ring and fluid level on both T1- and T2-weighted images, which was compatible with CEIH. RESULTS: Stereotactic evacuation and placement of an Ommaya reservoir were performed. CONCLUSION: The concentration of vascular endothelial growth factor was high in the hematoma, suggesting that CEIH may be similar to chronic subdural hematoma.

Neuroprotective and brain edema-reducing efficacy of the novel cannabinoid receptor agonist BAY 38-7271.

BAY 38-7271 is a new high-affinity cannabinoid receptor agonist with strong neuroprotective efficacy in a rat model of traumatic brain injury (acute subdural hematoma, SDH). In the present study we investigated CB1 receptor signal transduction by [35S]GTPgammaS binding in situ and in vitro to assess changes in receptor functionality after SDH. Further, we continued to investigate the neuroprotective properties of BAY 38-7271 in the rat SDH and transient middle cerebral artery occlusion (tMCA-O) model as well as the efficacy with respect to SDH-induced brain edema. [35S]GTPgammaS binding revealed minor attenuation of CB1 receptor functionality on brain membranes from injured hemispheres when compared to non-injured hemispheres or controls. In the rat SDH model, BAY 38-7271 displayed strong neuroprotective efficacy when administered immediately after SDH either as a 1 h (65% infarct volume reduction at 0.1 microg/kg) or short-duration (15 min) infusion (53% at 10 microg/kg). When administered as a 4 h infusion with a 5 h delay after injury, significant neuroprotection was observed (49% at 1.0 microg/kg/h). This was also observed when BAY 38-7271 was administered as a 5 h delayed 15 min short-duration infusion (64% at 3 microg/kg). In addition, the neuroprotective potential of BAY 38-7271 was demonstrated in the rat tMCA-O model, displaying pronounced neuroprotective efficacy in the cerebral cortex (91% at 1 ng/kg/h) and striatum (53% at 10 ng/kg/h). BAY 38-7271 also reduced intracranial pressure (28% at 250 ng/kg/h) and brain water content (20% at 250 ng/kg/h) when determined 24 h post-SDH. Based on these data it is concluded that the neuroprotective efficacy of BAY 38-7271 is mediated by multiple mechanisms triggered by cannabinoid receptors.

Semiquantitative expression analysis of ephrine-receptor tyrosine kinase mRNA's in a rat model of traumatic brain injury.

The molecular mechanisms involved in recovery of function of the central nervous system (CNS) after injury to the brain are incompletely understood. Here the expression of ephrine (Eph) kinases following traumatic brain injury (subdural haematoma) was analysed in order to find out whether these developmentally regulated genes may be involved in tissue remodelling after brain damage. mRNA was isolated from ipsilateral cortices 7, 18, and 28 days after surgery and semiquantitative reverse transcription-polymerase chain reaction was performed. Most Eph kinases did not show significant regulation at gene expression level during the time course of recovery from acute brain injury but there is some evidence that mRNA of EphB1 might be slightly upregulated.

Forensic significance of concentrations of ethanol in brain tissues following induced acute subdural hemorrhage.

The concentrations of ethanol in peripheral blood, subdural hematomas and various regions of the brain were determined 1, 2, 4, and 6 h after the induction of a hemorrhage into a subdural space in the right temple of rabbits. The concentrations were compared to cases of intravenous administration of ethanol-free i.v. fluid. Concentrations of ethanol in the subdural hematomas gradually decreased to correspond to those in the peripheral blood. The influence of an intravenous infusion of ethanol-free i.v. fluid was not observed. Concentrations in the brain of the right temporal, parietal and frontal lobes were high and those in the right temporal lobe were maintained during the 6 h of our experiment. Therefore, to determine if a human victim was under the influence of ethanol at the time of injury, we recommend that brain concentrations of ethanol be determined. This is apparently the first study to confirm that the estimation of ethanol in the brain provides a more accurate determination of how much ethanol had been ingested.

Subdural hematoma following traumatic brain injury causes a secondary decline in brain free magnesium concentration.

A number of studies have demonstrated that neurologic motor and cognitive deficits induced by traumatic brain injury (TBI) can be attenuated with administration of magnesium salts. However, many severe traumatic brain injuries have a significant hematoma that develops subsequent to the primary events, and it is unclear whether magnesium salts are effective in this situation. In the present study, an impact-acceleration rodent model of TBI was used to produce an injury that causes an extensive subdural hematoma in over 50% of injured animals. At 30 min after TBI, rats were randomly administered 250 micromoles/kg intravenous MgSO4 or equal volume saline before being monitored by magnetic resonance spectroscopy for 8 h to determine brain intracellular free magnesium concentration. Animals were then assessed for neurologic motor deficits over 1 week using a rotarod device, followed by postmortem examination for presence of subdural hematoma. Animals with subdural hematoma treated with MgSO4 showed no improvement in motor outcome when compared to nontreated controls. Animals with no visible subdural hematoma demonstrated a significant improvement (p < 0.05 by ANOVA) in rotarod scores with MgSO4 treatment. Brain free magnesium concentration in the magnesium treated/hematoma group demonstrated a biphasic decline made up of an immediate initial decline, recovery of brain magnesium levels with MgSO4 treatment, and then a significant second magnesium decline (p < 0.05). Such a secondary decline did not occur in the Mg treated/no hematoma animals. Our results suggest that development of a subdural hematoma following TBI results in a decline in brain magnesium, even after bolus administration of magnesium salts. Such effects of hematoma development will need to be considered in trials examining efficacy of magnesium salts as an intervention following TBI.

Artificial elevation of brain tissue glycerol by administration of a glycerol-containing agent. Case report.

In recent years the development of secondary brain damage and derangement of neurochemical parameters after severe head injury has been monitored using microdialysis. Provided the blood-brain barrier is intact, glycerol is regarded as a potential marker for membrane phospholipid degradation. The authors report a case in which marked elevation of interstitial glycerol was induced after exogenous administration of a glycerol-containing agent. A 25-year-old man was injured in a motorcycle accident and was admitted to the authors' institution with a unilateral dilated and fixed pupil and a Glasgow Coma Scale score of 3. Computerized tomography scans revealed a large subdural hematoma on the left side, subsequent midline shift, and generalized edema. Emergency craniotomy was performed for evacuation of the hematoma. The patient was prepared for multisensory monitoring and a microdialysis catheter was inserted into his left frontal lobe. After a routine enema containing 85% glycerol had been administered, the authors measured a marked increase in glycerol in the dialysate. This occurred while the patient was in as stable a condition as could be expected given the circumstances. The increase in interstitial glycerol in the injured tissue was most likely due to an impaired blood-brain barrier. Thus, the interstitial glycerol concentration had been corrupted by exogenous glycerol, and the marker properties of glycerol in this case became questionable. Consequently, administration of glycerol, which is frequently found in various infusions and emulsions, can promote secondary brain damage by adversely shifting osmotic gradients.

Expression of matrix metalloproteinases in the chronic subdural haematoma membrane.

To study the role of matrix metalloproteinases (MMP) in the development of chronic subdural haematoma, we investigated the expression and activity of MMPs (MMP-1, -2, -3, -7 and -9) and tissue inhibitors of MMP (TIMP-1 and -2) in capsules of chronic subdural haematoma from 10 patients. Outer membranes of chronic subdural haematoma were immunostained for MMP-1, MMP-2, MMP-9, TIMP-1 and TIMP-2. Moreover, we confirmed MMP activity in membranes by SDS-PAGE zymography and in situ zymography. These results suggest that MMP degrades extracellular matrix in outer membranes of chronic subdural haematoma, which is thought to decrease their integrity followed by direct haemorrhage and exudation of oedematous fluid from membrane vessels into the haematoma cavity.

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

Although both intracerebral and subdural hematomas induce brain edema, previous studies have indicated that they may have different cerebrovascular effects. Our own investigations have demonstrated that while subdural hematomas (SDH) are associated with ischemia this is not the case following intracerebral hematomas (ICH). Previous studies have demonstrated a decrease in energy-dependent transport of glutamine across the blood-brain barrier (BBB) following focal cerebral ischemia. The present study investigates this further by examining the effects of SDH, ICH, and intracerebral thrombin injections, an agent involved in ICH-induced injury, on blood to brain glutamine transport. The injection of 200 microL of blood into the subdural space induced a marked reduction in glutamine transport (Ki, influx rate constant) into the cerebral cortex at 4 and 24 h following SDH (sham, 105+/-4% of contralateral cortex; SDH 4 h, 63+/-5%, p<0.01; SDH 24 h, 47+/-12%, p<0.05). There were no significant changes in glutamine Ki in subcortical areas following SDH. Following ICH (200-microL clot); however, there were only modest decreases in glutamine Ki in subcortical areas (sham, 98+/-2% of right cortex; ICH 4 h, 91+/-5%, p<0.01; ICH 24 h, 91+/-2%, p<0.05). Intracerebral injection of thrombin (5U) had minimal effect on glutamine Ki, in subcortical areas, at 4 h and induced a modest decrease in transport at 24 h (sham, 98+/-2% of right cortex; thrombin 4 h, 98+/-2%; thrombin 24 h, 86+/-2%, p<0.05). The present studies demonstrate marked differences in the effects of ICH and SDH on BBB function.

Reducing hemoglobin oxygen affinity does not increase hydroxyl radicals after acute subdural hematoma in the rat.

Extensive evidence is available to show the importance of ischemia after severe human head injury. We have previously shown that pharmacologically increasing the release of oxygen in brain tissue where the local oxygen pressure is low reduces infarct size in animal models. To study the possible negative effects of this strategy, we tested the effect of an allosteric modifier of hemoglobin (RSR13) on free radical production in the rat acute subdural hematoma (ASDH) model, both under normoxic as well as under hyperoxic, normobaric conditions. When compared to baseline, induction of ASDH resulted in a significant increase (p < 0.05) in 2,3-DHBA (2,3 dihydroxybenzoic acid, produced from salicylate after attack by hydroxyl radicals) at 30 and 60 min postinduction, both for the control group (39% and 91%) as well as the RSR13-treated group (41% and 62%). The 2,5-DHBA also increased significantly (p < 0.05) in the drug-treated animals at the 30- and 60-min time points when compared to baseline (49% and 77%). At all time points, except the 30-min, the increase in 2,3-DHBA was less marked in the RSR13 animals than in the control group. Similarly, the 2,5-DHBA increase after ASDH was lower at all time points except for the 30-min time point in the RSR13-treated group. These results indicate that enhanced tissue oxygen release by the allosteric modifier of hemoglobin RSR13 does not increase hydroxyl radical production after ASDH. Clinical trials are needed to test this compound in humans after severe head injury.

Effect of hypocapnea on CBF and extracellular intermediates of secondary brain injury.

We examined the metabolic response of the brain underlying subdural hematomas or surrounding contusions to hyperventilation and looked for evidence of ischemia. Twelve consecutive patients with severe traumatic brain injury (TBI) (GCS < 8) who required surgery for evacuation of subdural hematoma or hemorrhagic contusion were studied. At surgery, a microdialysis catheter was placed into the cortex in a gyrus adjacent to the contusion or underlying the subdural hematoma. A thermal diffusion flow probe was placed on the cortex directly above the dialysis catheter. On days 1 and 3 post injury, two trials of hyperventilation were performed which dropped the patients' pCO2 10 mm Hg for 30 minutes. Monitoring of CBF and collection of dialysis fluid continued throughout each hyperventilation trial. Data was analyzed for a three hour window surrounding each hyperventilation. Brief periods of hyperventilation did not cause a significant elevation of the extracellular lactate/pyruvate ratio or glutamate level in areas of the brain likely to be the most vulnerable to secondary injury. In spite of hyperventilation leading to a significant decline in local CBF in 20% of the trials, there was no evidence of ischemia or excitatory amino acid release associated with hyperventilation.

Cortical cholinergic dysfunction after human head injury.

Loss of cholinergic neurotransmission is implicated in memory impairment and cognitive dysfunction after head injury. The aim of the present study was to investigate presynaptic markers, particularly in relation to cholinergic neurotransmission in human postmortem brain from patients who died following a head injury and age-matched controls. Choline acetyltransferase activity and high-affinity nicotinic receptor binding sites were assayed in the inferior temporal gyrus, cingulate gyrus, and superior parietal cortex of 16 head-injured patients and 8 controls. Synaptophysin immunoreactivity was determined in the left cingulate gyrus from the same patient groups. In the head-injured group, choline acetyltransferase activity was consistently reduced in each cortical region compared to control subjects. The presence of a subdural haematoma and a prolonged survival period after head injury tended to be associated with lower choline acetyltransferase activity. In contrast to the marked reduction in choline acetyltransferase activity, nicotine receptor binding was unchanged in head-injured compared to control patients. Synaptophysin immunoreactivity in the cingulate gyrus was reduced by approximately 30% (p < 0.05) in the head-injured group compared to controls. Correlation of choline acetyltransferase activity with synaptophysin immunoreactivity indicated there is a deficit of cholinergic presynaptic terminals in postmortem human brain following head injury.