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.

Use of tissue glue to prevent collapse of the cortical mantle during and after cranial surgery in children: a technical note.

INTRODUCTION: Young children with significant ventricular dilatation or large intracranial fluid spaces often have a very thin cortical mantle as a result of persistently raised intracranial pressure. This rim of cortex has a tendency to fall away from the dura into the cavity during and after intracranial surgery, due to the lack of support, once the pressure in the fluid cavity has been reduced. This can lead to tearing of cortical bridging veins and the formation of post-operative subdural haematomas. METHODS: We describe a simple technique that attempts to prevent this phenomenon occurring using tissue glue. Once the craniotomy has been performed and the dura has been formally opened, tissue glue is applied to the underside of the dura around the edge of the wound, prior to corticotomy. RESULTS AND CONCLUSION: This results in the cortical mantle adhering to the undersurface of the dura and prevents the mantle from falling into the cavity either during the procedure or post-operatively.

Phenytoin penetration into chronic subdural haematomas.

The pathophysiology of chronic subdural haematomas (CSH) is still unclear. In the light of recent ultrastructural examination, exudation from the macrocapillaries in the outer membrane of CSH may play an important role in the enlargement of CSH. In this study, exudation from the macrocapillaries was assessed by the measurement of phenytoin, a protein-bound antiepileptic agent used in cases of CSH. In 22 patients, 1 h after the administration of 250 mg of phenytoin intravenously, blood and subdural haematoma samples were taken and phenytoin levels were measured. The ratio of subdural haematoma level to the blood phenytoin level was determined and defined as the phenytoin penetration ratio (PPR). The correlation between the phenytoin penetration ratio and clinical neurological grades (Markwalder and Glasgow Coma Scale), age of the patients and the CT appearance of CSH were investigated. The mean phenytoin penetration ratio was 19.5%. As the neurological grades of patients increased, average PPR also increased. The average PPR values were 17.64 and 20.84% in the patients younger than 60 years (nine patients) and older patients (13 patients), respectively. Mean PPRs in the groups according to the CT appearance were as follows: low density 11.21% (seven patients), isodensity in 15.88% (10 patients), high density in 38.5% (five patients). A subdural reaccumulation was detected in nine patients with a mean PPR of 27.72%, while mean PPR was 14.56% in the others. Exudation from macrocapillaries in the outer membrane of chronic subdural haematomas probably plays an important role in the enlargement of chronic subdural haematoma, and measuring phenytoin levels in the chronic subdural haematoma is a simple method for the quantitative estimation of the exudation in CSH.

Development of a subdural vein thrombosis following aggressive factor VII replacement for postnatal intracranial haemorrhage in a homozygous factor VII-deficient infant.

Congenital factor VII deficiency is a rare (1:500,000) autosomally recessive coagulopathy with variable expression and high penetration. In infants the most devastating presentation is that of intracranial haemorrhage. An infant is described with severe factor VII deficiency who developed postnatal intracranial haemorrhage. The baby was treated with factor VII concentrate (ImmunoA.G., Vienna, Austria). Three weeks after the haemorrhage he developed a dural venous sinus thrombosis. Although factor VII-deficient patients may need treatment with factor VII concentrate, this needs to be carefully monitored because of the thrombotic risk.

Cerebral blood flow changes associated with fetal intracranial hemorrhages.

UNLABELLED: BACKGROUND AND MATERIAL: In order to evaluate cerebral blood flow changes associated with fetal intracranial hemorrhages, ultrasound and MRI examinations were carried out in four pregnancies with this complication. RESULTS: Increased resistance indices of the blood flow profile of the middle cerebral artery were detected in three of the fetuses, two of them presenting retrograde diastolic flow. Flow became normalized in one case within four weeks, changing on the contralateral side to an increased diastolic flow pattern. CONCLUSION: Increased intracranial pressure can cause these flow changes, but cerebral blood flow autoregulation need not be completely ruined in this complication.

Rate constant of gadolinium (Gd)-DTPA transfer into chronic subdural hematomas.

Gadolinium (Gd) DTPA concentrations in subdural fluid and arterial blood were measured following intravenous Gd-DTPA injection by ion coupled plasma emission spectrometry in 31 chronic subdural hematomas and 12 with subdural effusions. Dynamic biological modeling analysis was used to calculate the unidirectional transfer rate constant (K) for Gd-DTPA influx into the subdural fluid. The Gd concentrations in subdural hematomas and subdural effusions were 36.3 +/- 3.7 nmol ml(-1) and 80.0 +/- 14.0 nmol ml(-1), respectively. The transfer rate constants (K) for subdural hematomas and subdural effusions were 12.4 +/- 1.5 (x10(-4)) min(-1) and 19.7 +/- 2.2(x10(-4)) min(-1), respectively. The Gd concentration and transfer rate constant for subdural effusions were significantly (p<0.05) higher than for subdural hematoma. The Gd transfer rate constant was significantly correlated with the interval from head injury to operation. The present study shows that the immature outer membrane has a high transfer rate constant, allowing extravasation of plasma components into the subdural space and increasing the volume of the subdural effusion; the rate constant decreases with aging of the subdural hematoma.

Arterial circulation of the spinal cord and brain in the Monodontidae (order Cetacea).

In this paper we document retial supply of the spinal cord and describe the arterial vascular pattern of the brain in the whale family Monodontidae. Observations are based on gross dissections of four brains, two each of Monodon monoceros and Delphinapterus leucas, and one spinal cord from M. monoceros. Vessels of the spinal cord arise from extradural retia in the neural canal. Arteries originating from the retia penetrate the dura between successive spinal roots (mainly ventral) and not in association with them, unlike radicular arteries of other mammals. Also, these vessels are uniformly distributed and contribute equally to a plexus surrounding the cord. An A. radicularis magna is not present, and neither are distinct anterior or posterior spinal arteries. Circulation to the brain is effected by two pairs of arteries originating from intracranial retia. The rostral pair supplies most of the forebrain (prosencephalon), whereas the more caudal pair supplies mainly the midbrain (mesencephalon) and hindbrain (rhombencephalon). The circulatory pattern is characterized by 1) complete independence of anterior cerebral arteries (no anastomoses); 2) extensive cortical supply by the anterior choroidal arteries; 3) absence of subdural communicating vessels between rostral and caudal trunks; 4) union of caudal trunks to form a small basilar artery; and 5) absence of vertebral arteries and hence of a vertebral basilar system. There are some obvious differences between subdural arteries in the Monodontidae and those in other mammals; however, their general patterns of distribution are similar, and we suggest that most of the vessels, at least in the cranium, are homologous.

[Electron microscopic study of the process of the removal of autogenous blood erythocytes beyond the limits of the subdural space]. / Elektronno-mikroskopicheskoe issledovanie protsessa udaleniia éritrotsitov autogennoi krovi za predely subdural'nogo prostranstva.

The internal plate of the dura mater and arachnoidea of the dob brain was studied by electron microscopy after introducing 0.3--0.5 ml of the autogenous blood into the subdural space. The arachnoidea of the excretory channels and structural elements of the internal plate of the dura mater (cells of the internal covering layer, the collagen fibril and microfibril layer, the wall of the blood capillaries of the internal capillary network) involve the morphological substratum of the liquor-blood barrier-I between the liquor and blood of the blood capillaries of the internal capillary network of the dura mater. It was established that red cells of the subdural space penetrate the thickness of the dura mater, where they concentrate around blood capillaries of the internal capillary network, rather than penetrate into the arachnoidea.