Cerebral perfusion pressure and behavior monitoring in freely moving rats.

Cerebral perfusion pressure (CPP) is the net pressure gradient that drives oxygen delivery to cerebral tissue. It is the difference between the mean arterial pressure (MAP) and the intracranial pressure (ICP). As CPP is a calculated value, MAP and ICP must be measured simultaneously. In research models, anesthetized and acute monitoring is incapable of providing a realistic picture of the relationship between ICP and MAP under physiological and/or pathophysiological conditions. For long-term monitoring of both pressures, the principle of telemetry can be used. The aim of this study was to map changes in CPP and spontaneous behavior using continuous pressure monitoring and video recording for 7 days under physiological conditions (group C - 8 intact rats) and under altered brain microenvironment induced by brain edema (group WI - 8 rats after water intoxication) and neuroprotection with methylprednisolone - MP (group WI+MP - 8 rats with MP 100 mg/kg b.w. applicated intraperitoneally during WI). The mean CPP values in all three groups were in the range of 40-60 mm Hg. For each group of rats, the percentage of time that the rats spent during the 7 days in movement pattern A (standard movement stereotype) or B (atypical movement) was defined. Even at very low CPP values, the standard movement stereotype (A) clearly dominated over the atypical movement (B) in all rats. There was no significant difference between control and experimental groups. Chronic CPP values with correlated behavioral type may possibly answer the question of whether there is a specific, universal, optimal CPP at all.

Determination of brain water content by dry/wet weight measurement for the detection of experimental brain edema.

Brain edema is a fatal pathological state in which brain volume increases as a result of abnormal accumulation of fluid within the brain parenchyma. A key attribute of experimentally induced brain edema - increased brain water content (BWC) - needs to be verified. Various methods are used for this purpose: specific gravimetric technique, electron microscopic examination, magnetic resonance imaging (MRI) and dry/wet weight measurement. In this study, the cohort of 40 rats was divided into one control group (CG) and four experimental groups with 8 rats in each group. The procedure for determining BWC using dry/wet weight measurement was initiated 24 h after the completion of edema induction by the water intoxication method (WI group); after the intraperitoneal administration of Methylprednisolone (MP) together with distilled water during edema induction (WI+MP group); 30 min after osmotic blood brain barrier disruption (BBBd group); after injection of MP via the internal carotid artery immediately after BBBd (BBBd + MP group). While induction of brain edema (WI, BBBd) resulted in significantly higher BWC, there was no increase in BWC in the MP groups (WI+MP, BBBd+MP), suggesting a neuroprotective effect of MP in the development of brain edema.

Effect of methylprednisolone on experimental brain edema in rats - own experience reviewed.

Brain edema - a frequently fatal pathological state in which brain volume increases resulting in intracranial pressure elevation - can result from almost any insult to the brain, including traumatic brain injury. For many years, the objective of experimental studies was to find a method to prevent the development of brain edema at the onset. From this perspective, the use of methylprednisolone (MP) appears promising. High molecular MP (MW>50 kDa) can be incorporated into the brain - in the conditions of the experimental model - either by osmotic blood-brain barrier disruption (BBBd) or during the induction of cellular edema by water intoxication (WI) - a condition that increases the BBB permeability. The time window for administration of the MP should be at the earliest stages of edema. The neuroprotective effect of MP on the permeability of cytoplasmatic membranes of neuronal populations was proved. MP was administrated in three alternative ways: intraperitoneally during the induction of cytotoxic edema or immediately after finishing cytotoxic edema induction in a dose of 100 mg/kg b.w.; into the internal carotid artery within 2 h after finishing cytotoxic edema induction in a dose of 50 mg/kg b.w.; into internal carotid artery 10 min after edema induction by BBBd in a dose of 50 mg/kg b.w.

Effect of methylprednisolone on experimental brain edema in magnetic resonance imaging.

Magnetic resonance imaging has been used for evaluating of a brain edema in experimental animals to assess cytotoxic and vasogenic edema by the apparent diffusion coefficient (ADC) and T2 imaging. This paper brings information about the effectiveness of methylprednisolone (MP) on experimental brain edema. A total of 24 rats were divided into three groups of 8 animals each. Rats with cytotoxic/intracellular brain edema induced by water intoxication were assigned to the group WI. These rats also served as the additional control group CG when measured before the induction of edema. A third group (WIMP) was intraperitoneally administered with methylprednisolone 100 mg/kg during water intoxication treatment. The group WI+MP was injected with methylprednisolone 50 mg/kg into the carotid artery within two hours after the water intoxication treatment. We evaluated the results in four groups. Two control groups (CG, WI) and two experimental groups (WIMP, WI+MP). Rats were subjected to MR scanning 24 h after edema induction. We observed significantly increased ADC values in group WI in both evaluated areas - cortex and hippocampus, which proved the occurrence of experimental vasogenic edema, while ADC values in groups WIMP and WI+MP were not increased, indicating that the experimental edema was not developed and thus confirming the protective effect of MP.

Forelimb Movement Disorder in Rat Experimental Model.

Study of motor activity is an important part of the experimental models of neural disorders of rats. It is used to study effects of the CNS impairment, however studies on the peripheral nervous system lesions are much less frequent. The aim of the study was to extend the spectrum of experimental models of anterior limb movement disorders in rats by blockade of the right anterior limb brachial plexus with the local anesthetic Marcaine (Ma), or with aqua for injection administered into the same location (Aq) (with control intact group C). Two other groups with anterior limb movement disorders underwent induction of cellular brain edema by water intoxication (MaWI and AqWI). Results showed a lower spontaneous motor activity of animals in all experimental groups versus controls, and lower spontaneous motor activity of animals in the MaWI group compared to other experimental groups in all categories. There was no difference in spontaneous activity between the groups Ma, Aq and AqWI. Our study indicates that alterations of spontaneous motor activity may result from the impaired forelimb motor activity induced by the anesthetic effect of Marcaine, by the volumetric effect of water, as a result of induced brain edema, or due to combination of these individual effects.

Loss of body weight is accompanying cellular brain edema induced by water intoxication in the rat.

Induction of cellular cerebral edema (CE) was achieved by a standard method of water intoxication which consisted of fractionated intraperitoneal administration of distilled water (DW) together with the injection of desmopressin (DP). Using metabolic cage, fluid and food balance was studied in two groups of eight animals: group C - control; group CE - cellular edema induced by water intoxication. For each rat the intake (food pellets and water) and excretion (solid excrements and urine) were recorded for 48 h together with the initial and final body weight. CE animals consumed significantly less food, drank less water and eliminated the smallest amount of excrements. The induction of cellular cerebral edema was accompanied with a significant loss of body weight (representing on average 13 % of the initial values) mainly due to a reduction of food intake. This phenomenon has not yet been reported.

Methylprednisolone modulates intracranial pressure in the brain cellular edema induced by water intoxication.

Continuous monitoring of the intracranial pressure (ICP) detects impending intracranial hypertension resulting from the impaired intracranial volume homeostasis, when expanding volume generates pressure increase. In this study, cellular brain edema (CE) was induced in rats by water intoxication (WI). Methylprednisolone (MP) was administered intraperitoneally (i.p.) before the start of CE induction, during the induction and after the induction. ICP was monitored for 60 min within 20 h after the completion of the CE induction by fibreoptic pressure transmitter. In rats with induced CE, ICP was increased (Mean+/-SEM: 14.25+/-2.12) as well as in rats with MP administration before the start of CE induction (10.55+/-1.27). In control rats without CE induction (4.62+/-0.24) as well as in rats with MP applied during CE induction (5.52+/-1.32) and in rats with MP applied after the end of CE induction (6.23+/-0.73) ICP was normal. In the last two groups of rats, though the CE was induced, intracranial volume homeostasis was not impaired, intracranial volume as well as ICP were not increased. It is possible to conclude that methylprednisolone significantly influenced intracranial homeostasis and thus also the ICP values in the model of cellular brain edema.

Signs of myelin impairment in cerebrospinal fluid after osmotic opening of the blood-brain barrier in rats.

A number of clinical neurological pathologies are associated with increased permeability of the blood brain barrier (BBB). Induced changes of the homeostatic mechanisms in the brain microenvironment lead among others to cellular changes in the CNS. The question was whether some of these changes can be induced by osmotic opening of BBB in an in vivo experiment and whether they can be detected in cerebrospinal fluid (CSF). CSF was taken via the suboccipital puncture from 10 healthy rats and six rats after the osmotic opening of the BBB. In all 16 animals, concentration of myelin basic protein (MBP ng/ml), Neuron-specific enolase (NSE ng/ml) and Tau-protein (Tau pg/ml) were determined in CSF by ELISA. Values in both groups were statistically evaluated. Significant difference between the control and experimental group was revealed only for the concentration of myelin basic protein (p<0.01). The presented results indicate that osmotic opening of the BBB in vivo experiment without the presence of other pathological conditions of the brain leads to a damage of myelin, without impairment of neurons or their axons.

Influence of low-dose neonatal domoic acid on the spontaneous behavior of rats in early adulthood.

Consumption of seafood containing toxin domoic acid (DA) causes an alteration of glutamatergic signaling pathways and could lead to various signs of neurotoxicity in animals and humans. Neonatal treatment with domoic acid was suggested as valuable model of schizophrenia and epilepsy. We tested how repeated early postnatal DA administration influences the spontaneous behavior of rats in adulthood. Rats were injected with 30 microg DA/kg from postnatal day (PND) 10 until PND 14. Their behavior was observed in the open field test for one hour (Laboras, Metris) at PND 35, PND 42 and PND 112. We did not find any difference between DA treated rats and animals injected with equivalent volume of saline in both test sessions at PND 35 and PND 42. DA rats at PND 112 exhibited significantly higher vertical and horizontal exploratory activity (tested parameters: locomotion, distance travelled, average speed reached during test, grooming and rearing) between the 30th-40th min of the test session and habituated over 10 min later. We conclude that at least in the given experimental design, neonatal DA treatment results in alteration of the spontaneous behavior of rats in adulthood.

CT imaging and spontaneous behavior analysis after osmotic blood-brain barrier opening in Wistar rat.

In our previous experiments we demonstrated that osmotic opening of the blood brain barrier (BBB) in rats by administration of mannitol into the internal carotid artery leads to cerebral edema. The aim of this study was to confirm objectively the development of brain edema and determine whether it affects spontaneous locomotor activity in rats (SLA). Brain edema was verified by computer tomography (CT) examination of the brain and SLA was observed during open field test. Twenty four adult male rats were divided into four groups of six: (1) control animals (C), (2) controls with anesthesia (CA), (3) controls with sham surgery (CS), (4) experimental - osmotic opening of the BBB (MA). Osmotic BBB disruption manifested by reducing the density of brain tissue (hypodensity), suggesting a higher water content in the brain tissue. SLA was compared between C, CA, CS and MA groups and between MA and CA groups. Significant difference was found only between the control group and MA group. In the first 30 min of the examination, rats after the mannitol administration revealed a marked limitation of spontaneous locomotor activity. Experimental results demonstrated reduction of spontaneous locomotor activity in rats with induced brain edema.

Both water intoxication and osmotic BBB disruption increase brain water content in rats.

Our previous experiments revealed that water intoxication and osmotic BBB disruption in the rat allow penetration of high-molecular substances into the brain and that resulting changes in the internal environment of the CNS lead to pathological development, such as the loss of integrity of myelin. The aim of the present study was to determine whether the previously described phenomena are associated with increased water content in the brain. To answer the question following methods were used: a) water intoxication: intraperitoneal administration of distilled water, b) osmotic BBB disruption: application of mannitol (20 %) selectively into the internal carotid artery, c) brain wet weight was measured after decapitation, and subsequently (after six days in thermostat set at 86 °C) the dry weight were estimated d) in animals with 20 % and 30 % hyperhydration the degree of myelin deterioration was estimated e) animal locomotor activity was tested by continuous behavior tracking and analysis. Brain water content after water intoxication and following the administration of mannitol was higher than in the control group. Different degrees of hyperhydration led to different levels of brain water content and to different degrees of myelin impairment. Hyperhydration corresponding to 20 % of the body weight brought about lower locomotor activity. Increased water content in the brain after the BBB osmotic disruption is surprising because this method is frequently used in the clinical practice.

The MRI volumetry of the posterior fossa and its substructures in trigeminal neuralgia: a validated study.

PURPOSE: Our aim was to determine whether the anatomical configuration of the posterior fossa and its substructures might represent a predisposition factor for the occurrence of clinical neurovascular conflict in trigeminal neuralgia (TN). METHODS: We used MRI volumetry in 18 patients with TN and 15 controls. The volume of the pontomesencephalic cistern, Meckel's cave and the trigeminal nerve on the clinical and non-affected sides was compared. The reliability has been assessed in all measurements. RESULTS: The posterior fossa volume was not different in the clinical and control groups; there was no difference between the affected and non-affected sides when measuring the pontomesencephalic cistern and Meckel's cave volume either. The volume of the clinically affected trigeminal nerve was significantly reduced, but with a higher error of measurement. CONCLUSIONS: We did not find any association between the clinical neurovascular conflict (NVC) and the size of the posterior fossa and its substructures. MRI volumetry may show the atrophy of the affected trigeminal nerve in clinical NVC.

Chordoid meningioma: presentation of two case reports, review of the literature, and plea for data standardisation.

Chordoid meningioma is a rare variant of meningioma with histological features resembling those of chordoma. This tumour should have a greater risk of recurrence and aggressive growth (WHO grade II). So far, 92 such tumours have been described in the literature. We report two cases of chordoid meningioma occurring in adult female patients. In our two patients (aged 28 and 60 years with chordoid meningioma of the convexity and left-sided outer sphenoid wing, respectively) we centred on some rarely discussed aspects of the tumour. MRI scans showed no edema in the vicinity of either of the two meningiomas, whereas selective angiography of ACI and ACE revealed a dural type of vascular supply to the two neoplasms. In both cases, the tumour was removed by radical surgery (Simpson grade I resection) with a normal post-operative course. Both women (one 2 years post-surgery and one 4 years post-surgery) are now free from any signs of relapse on MRI and with normal neurological findings. The vascular endothelial growth factor (VEGF) expression was low in either case (5 and 40%, respectively). We regard the factors under consideration in our study (i.e. absence of edema, dural supply, low VEGF expression and radical Simpson grade I resection) as an important contribution to the discussion of the biological behaviour of chordoid meningioma.

Preoperative neuroimage findings as a predictor of postoperative neurological deficit in intracranial meningiomas.

BACKGROUND: The present study aimed to find radiological parameters that can provide indirect information on the invasive growth of meningioma relevant enough to predict the likely risk of postoperative neurological deficit. MATERIAL/METHODS: The cohort consisted of 40 consecutive adult patients (from January 2004 till May 2005) with comparable general condition parameters (age 18-75 years, KRS 70-100, ASA 1-2) with meningiomas solely attacking brain tissue with the whole of their volume. The Pearson chi-square test was used for statistical evaluation. RESULTS: Radical resection of the meningioma was attained in 33 (82.5%) patients and subtotal resection in 7 (17.5%). Ten (25%) patients at 7 days after the operation had neurological findings which were worse than before. Seven were found to have a new neurological deficit and there were three cases of progression of the existing neurological symptoms. Three patients (7.5%) were worse off neurologically than before the operation as long as 3 months after surgery, while seven had their neurological condition restored ad integrum. All of the ten patients with postoperatively worsened neurological findings had their meningiomas localised in the eloquent area. A correlation was found between the eloquent area and neurological deficits, and also between the presence of peritumoral oedema (small, medium, large) and neurological deficits. Interdependence was detected between a discernible tumour-brain interface and the absence of oedema, between a discernible tumour-brain interface and a dural type of vascular supply, and between the dural type of vascularisation and an absence of oedema. CONCLUSIONS: As follows from the outcomes, meningioma growth in the eloquent area and the presence of peritumoral oedema are the two adverse parameters predicting the development of postoperative neurological deficits. In contrast, dural types of vascularisation, a visible tumour-brain interface, meningioma growing in a non-eloquent area, and the absence of peritumoral oedema are favourable predictive parameters. To go by the results, in the presence of the last two parameters the patient need not be exposed to the risks of invasive selective angiography.

Molecular cytogenetic stratification of recurrent oligodendrogliomas: utility of interphase fluorescence in situ hybridization (I-FISH).

In oligodendroglial brain tumours, losses of chromosomal material of the short arm of chromosome 1 and long arm of chromosome 19 have been shown to predict responsiveness to chemotherapy and prolonged patients' survival. Therefore, the correct diagnosis of these genetic alterations in tumours of oligodendroglial origin is particularly important. To detect deletions of 1p36 and/or 19q13.3 in oligodendroglial cells we used dual-colour I-FISH with locus-specific DNA probes. I-FISH was performed on isolated whole cell nuclei, prepared from fresh non-fixed tumour tissue samples resuspended in media and processed using a standard cytogenetic procedure, thus bypassing the problem of nuclear truncation. We examined 16 patients with histologically proved oligodendrogliomas (5x oligodendroglioma, 9x anaplastic oligodendroglioma, 2x anaplastic oligoastrocytoma). The results of molecular cytogenetic analyses were correlated with morphological and clinical findings. Molecular cytogenetic analyses were successful in 15 patients and, due to a non-adequate tissue specimen, were uninformative in one patient only. Combined deletions 1p36/19q13 were proved in 13 patients. However, in six of them additional genetic alterations typical for high-grade astrocytoma were found, which could have negative influence on the prognosis. One patient had isolated deletion of 1p36 and another had a normal genetic pattern without any chromosomal alterations. In summary, I-FISH on isolated cell nuclei is a powerful tool for detecting chromosomal aberrations in tumour cells. A systematic molecular cytogenetic analysis may advance diagnosis, prognostic stratification, and targeted treatment of patients with brain tumours.

[Intracranial meningiomas; standard diagnostic procedure and results of surgical treatment]. / Nitrolební meningiomy; standardní diagnostický postup a vý1sledky operacní lécby.

The aim of the study is to define radiological parameters which may indirectly indicate invasive expansion of a meningioma and thus forecast potential risks of postoperative neurological deficits. The study group includes 40 adult patients in comparable physical conditions (age 18-75, CRS 70-100, ASA 1-2) with meningiomas, affecting the brain tissue only. The results indicate that unfavorable parametres, predicting potential postoperative neurological deficits include: growth of a meningioma in eloquent regions and presence of a peritumoral oedema. Positive parametres, indicating that no neurological deficit would arise, include: dural supply, visible brain-tumor barrier, non-eloquent location of a meningioma and absence of a peritumoral oedema. The study results suggest that provided the two last parametres are present, a patient need not be exposed to risks of invasive selective angiography.

Intracranial meningioma surgery outcome--the impact of preoperative neuroimaging.

The present study is aimed at finding radiological parameters which could provide indirect information on invasive growth of meningioma, relevant enough to predict the possible risk of postoperative neurological deficit development. The cohort was composed of 40 consecutive adult patients of comparable general condition parameters (age 18-75 years, KRS 70-100, ASA 1-2) with meningiomas attacking with the whole of their volume solely the brain tissue. As follows from the outcome, meningioma growth in the eloquent area and the presence of peritumoral oedema are the two adverse parameters predicting the development of postoperative neurological deficit. In contrast, dural type of vascularisation, visible tumour-brain interface, meningioma growing in a non-eloquent area and the absence of peritumoral oedema are favourable predictive parameters. According to our results, if the last two of those parameters are present, the patient need not to be exposed to the risks of invasive selective angiography.

[Intracranial meningiomas--criteria for selection of the optimum therapeutic modality]. / Nitrolební meningiomy; kritéria pro výber optimální léebné modality.

The authors present their own proposal for a standard diagnostic procedure algorithm in intracranial meningiomas, which they used in their prospective, non-randomized longitudinal study in a group of 30 subjects within a year. The following four criteria were assessed in each patient: age, physical condition according the ASA classification, location of the meningioma on the MRI (superficial, the scull base) and the growth invasivity using selective DSA (ACI+ACE) and MRI (the vascularization type, the oedema index and the change in the oedema signal intensity in 3.5 hours). The criteria helped to establish the optimum therapeutic procedure for each patient: embolisation without a follow-up surgery (2 subjects), observation (2 subjects), pre-operative embolisation (5 subjects) and surgery without preceeding embolisation (21 subjects). This study did not assess the intracranial meningiomas treatment outcome. It highlights significance of the diagnostic procedures standardization in order to establish their optimum therapeutic modality.

Effects of intracarotid injection of methylprednisolone on cellular oedema after osmotic opening of the blood-brain barrier in rats.

In our work we studied methylprednisolone (MP) for its effects on the permeability of cytoplasmatic membranes of neuronal populations in the rat. We used a standard model of cellular oedema induced by water intoxication, applying MP selectively into the internal carotid (ICA) after opening the blood-brain-barrier (BBB) with mannitol. The results were assessed under fluorescence microscopy in keeping with the Intracellular Distribution Index of Evans Blue (IDI) in the neocortical field (Cortex) and in hippocampal areas CA1, CA3 and GD. Evans blue (EB) was applied similarly as MP Three different experiments were carried out. In experiment 1--EB alone and no MP was applied. In experiment 2--5.4 mg/kg MP and EB were applied. In experiment 3--54 mg/kg MP and EB were applied. In experiment 1 the IDI values were high (>1), indicating the presence of large quantities of EB in the cells. In experiments 2 and 3 the IDI values were low (<1), indicating more EB outside than inside cells. IDI differences between experiments 2 and 1 and experiments 3 and 1 were statistically significant (p<0.05). This morphological evidence sufficiently proved the possibility to restore the cell membrane integrity by means of MP administration.

Altered blood-brain barrier permeability and its effect on the distribution of Evans blue and sodium fluorescein in the rat brain applied by intracarotid injection.

The aim was to study the blood-brain permeability according to the distribution in the rat brain of Evans blue (EB) and sodium fluorescein (NaFl) administered by an intracarotid injection. Eighteen animals were divided into six groups according to the state of the blood-brain barrier (BBB) at the moment when the dyes were being applied. In the first two groups, the BBB was intact, in groups 3 and 4 the barrier had been opened osmotically prior to the application of the dyes, and in groups 5 and 6 a cellular edema was induced by hyperhydration before administration of the dyes. The intracellular and extracellular distribution of the dyes was studied by fluorescence microscopy. The histological picture thus represented the morphological correlate of the way BBB permeability had been changed before the application of the dyes.