Ruptured tectal arteriovenous malformation demonstrated angiographically after removal of an unruptured occipital lobe arteriovenous malformation.

We report a case of ruptured tectal arteriovenous malformation (AVM) that was demonstrated angiographically only after removal of an unruptured occipital AVM. A 57-year-old man presented with sudden onset of diplopia and tinnitus. Computed tomography revealed a small hemorrhage in the right tectum mesencephali with intraventricular hemorrhage. Magnetic resonance imaging and angiography disclosed AVM in the right occipital lobe which was separate from the hemorrhagic lesion. Angiography demonstrated that the right occipital AVM was fed by the parieto-occipital artery and drained into the superior sagittal sinus and vein of Galen. However, no abnormal vascular lesion was detected near the tectum mesencephali. As venous hypertension was considered the reason for hemorrhage, the occipital AVM was completely resected. Postoperative angiography demonstrated disappearance of the occipital AVM, but it also disclosed a small tectal AVM fed by branches from the superior cerebellar artery, which had not been detected on preoperative angiography. This was considered the true cause of hemorrhage, and gamma knife surgery was accordingly performed. Even if an AVM is demonstrated, if the lesion does not correspond to the hemorrhage we recommend serial angiographical evaluation so that a small AVM is not missed.

Three-dimensional computed tomography angiography of the galenic system for the occipital transtentorial approach.

The venous variations of the galenic system were evaluated using three-dimensional computed tomography angiography (3D-CTA) to assess the influence on the occipital transtentorial approach in 150 patients who underwent 3D-CTA as a routine screening examination for cerebrovascular diseases. The variations of the vein of Galen with its tributaries, the tentorial sinus, and the veins around the tentorium were evaluated in multiple intensity projections and stereoscopic images. The angle between the vein of Galen and the straight sinus was 67.1 +/- 31.9 degrees (mean +/- SD). Observation of the pineal body from the direction of the approach tended to extend to the quadrigeminal bodies in acute angle cases, and to the third ventricle in obtuse angle cases. Bilateral internal cerebral veins (ICVs) joined in the anterior portion were associated with a long vein of Galen, or in the posterior portion with a short vein of Galen. The distance between the bilateral ICVs was 4.66 +/- 2.28 mm (mean +/- SD), and the shape of the space could be classified as spindle, parallel, hairpin, and round types. The basal vein could be classified into well-developed, hypoplastic, hardly recognized, and mimicking two basal veins because the tributary did not join but ran parallel to the basal vein. The drainage pathways lead to the anterior or posterior portion of the vein of Galen, the ICV, the tentorial sinus, and the superior petrosal sinus. The various types of the tentorial sinus and primitive tentorial sinus which might be sacrificed during section of the tentorium were confirmed. The inferior cerebral vein draining to the tentorial sinus could be seen. 3D-CTA could also demonstrate the presence, the course, and the drainage points of the internal occipital vein, the precentral cerebellar vein, the posterior pericallosal vein, and so on. 3D-CTA is useful to evaluate the variations of the venous system and the relationship with the tumor, and for preoperative simulation and intraoperative navigation of the occipital transtentorial approach.

Quadrigeminal variant of perimesencephalic nonaneurysmal subarachnoid hemorrhage.

OBJECTIVE: Perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSH) is a benign entity with a low risk of rebleeding. The most widely accepted definition emphasizes the presence of blood ventral to the midbrain or pons on early computed tomography. We sought to determine the frequency of PNSH with blood centered in the quadrigeminal cistern. METHODS: We reviewed a prospectively collected database of all patients admitted to our institution over a 2.5-year period with subarachnoid hemorrhage (SAH) and identified PNSH patients from early computed tomographic scans and negative four-vessel angiograms. RESULTS: Of 220 SAH patients, we identified 9 with PNSH. Two (22%) of these patients had SAH centered in the quadrigeminal cistern without pretruncal blood, negative repeat angiograms, and an uncomplicated clinical course. CONCLUSION: Quadrigeminal SAH is a variant of PNSH that is not well described in the literature. It may comprise up to one-fifth of PNSH cases and carries a similar benign prognosis.

Vascularization of the brain in guinea pig. IV. Angioarchitectonics of the tectum, tegmentum, and crura mescencephali.

Out of three parts of the midbrain the richest vascularization is observed in the tegmentum in which are localized many nuclei. Particularly abundant blood supply shows the main nucleus of the oculomotor nerve. Less vascularized is the central oculomotor nucleus, and scanty blood vessels are found within the autonomic nucleus of the oculomotor nerve. Dense vascular net is found in the supratrochlear nucleus which lies in the central gray substance of the midbrain. Also, dense vascular net is noted within the red nucleus, trochlear nucleus, and the dorsal raphe nucleus. Within the substantia nigra less vascularized is its compact part. Very weak vascularization is observed in the periaqueductal gray and in the crura cerebri. Within the tectum more blood vessels are found in the inferior colliculus as compared with the superior colliculus. Within the crura cerebri the blood vessels do not form vascular net and they ascend into tectum and tegmentum.

Perivascular astrocytes and endothelium in the development of the blood-brain barrier in the optic tectum of the chick embryo.

The role played by perivascular astrocytes in neural vessel maturation was investigated in microvessels of the chick embryo optic tectum. Three-dimensional reconstructions and quantitative analyses were made, and permeability was studied. On embryonic days 14-16, 12.5% of the microvessel wall is surrounded by astrocyte endfeet which, in most cases (82%), are located under endothelium junctions; the latter, at this stage, partly prevent the extravascular escape of the marker horseradish peroxidase. On days 18-21, the astrocyte processes form a nearly complete perivascular sheath enveloping 96% of the microvessel perimeter; the junctions of the endothelial cells are much wider and impermeable owing to extensive fusion of the endothelial plasma membranes. This investigation suggests a close relationship between the perivascular arrangement of glia and differentiation of the endothelium tight junctions and indicates that the morphofunctional maturation of the latter takes place progressively during the prenatal organogenesis of the chick central nervous system.

[Morphofunctional state of vascular wall components in the rat brain following gamma-irradiation of the head]. / Morfofunktsional'noe sostoianie nekotorykh komponentov stenki sosudov mozga krys posle gamma-oblucheniia golovy.

The histochemical methods were used to study alkaline phosphomonoesterase of capillaries, glycosaminoglycanes of vascular walls, and tissular basophils of rat brain after local gamma-irradiation of the head with doses of 51.6-645 mC/kg. During the first minutes and hours after irradiation, the actively functioning capillary network lengthened and secretion of indolylamines by tissular basophils increased. It is assumed that the changes observed are compensatory.

The venous drainage of the tectum mesencephali. An anatomical angiographic study of the quadrigeminal veins.

The normal course and appearance of the veins draining the tectum mesencephali proper are described in detail on the basis of the anatomical radiological study. These specific veins, the quadrigeminal veins, were constantly present on autopsy study. There are two types of variations of these quadrigeminal veins. They have a close anatomical and angiographic correlation with the quadrigeminal plate proper, and also outline the posterior aspects of the quadrigeminal plate. The whole structure of the mesencephalon may be delineated by these veins in combination with the other veins of the mesencephalon. They may be of diagnostic value in the early recognition of the brain stem lesions.

Rapid changes in cerebral blood flow and initial visual experience in the developing chick.

A single eye of young chicks was sewed shut for various times. Regions contralateral to and primarily or secondarily innervated by the sutured eye had a reduced rate of cerebral blood flow in comparison to the corresponding ipsilateral regions. However, upon reopening the sutured eye after 2 days, these contralateral regions (optic lobes and cerebral hemispheres) exhibited a rapid increase in cerebral blood flow to a level significantly above that in control ipsilateral areas. The duration of this effect was considerably prolonged in chicks that were monocularly sutured immediately after hatching without prior exposure to light. Chicks that had 1 week of normal vision before monocular suture did not show this overcompensatory effect. If the period of monocular suture was extended to 7 days before restoration of vision to the occluded eye, the overcompensatory vascular effect was delayed. The maximal effect was apparent only upon the 1st exposure of an eye to major visual input. A possible relation exists between this rapid increase in regional blood flow and the period when visual imprinting could normally be expected to be maximal.