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Biomedical subjects

S Velut

Publications and source records attributed to S Velut.

33 records · Page 2Linked to original sources
PubMed1994

Surgical anatomy and dissection of the petrous and peripetrous area. Anatomic basis of the lateral approaches to the skull base.

The purpose of this study is to review the topographic anatomy of the petrous and peripetrous structures, with emphasis on the relationships important to the lateral approaches to the posterior and lateral skull base. Surgical exposure of the clivus, the posterior aspect of the petrous bone, the ventral aspect of the brain stem, and of all the intradural structures in the area, remains difficult because of the presence of the so-called "petrous and peripetrous complex". However, the lateral approach to the skull base is the most suitable approach if the lesion lies lateral to the cavernous portion of the internal carotid artery, and of course if the lesion develops laterally behind the petrous apex. Consequently, neurosurgeons should be familiar with the anatomy of the intrapetrous cavities and their contents, and with the relationships in the area. Middle cranial fossa dissections (dry and fresh specimens) allow us to study the anatomical relationships between the intrapetrous carotid artery, the facial nerve, the porus, the cochlea, the geniculate ganglion and the petrosal nerves, the trigeminal ganglion and nerve, the auditory tube and the middle ear. While briefly reviewing some approaches (anterior petrosectomy, sub-temporal preauricular infratemporal fossa approach, pre-sigmoid approach), we explore the concept of the approach and the limitations of surgical technique and exposure.

Humans↗
PubMed1993

Smooth pursuit eye movement deficits after pontine nuclei lesions in humans.

Eye movements were recorded electroculographically in four patients with basal pontine lesions, demonstrated by MRI. The most prominent eye movement abnormality observed was mild to severe impairment of smooth pursuit and optokinetic nystagmus, mainly ipsilateral to the lesion. This abnormality is thought to result from damage to the pontine nuclei, which form a crucial relay between the cerebral cortex and the cerebellum controlling smooth pursuit. Abnormalities of saccades and the vestibulo-ocular reflex in one patient are also discussed.

Adult↗
PubMed1993

[French language Society of Neurosurgery. 44th Annual Congress. Brussels, 8-12 June 1993. Tumors of the foramen magnum].

Since what seems to be the first reported case of foramen magnum (F.M.) tumor by Hallopeau in 1874, literature on tumoral pathology of this region is rather scarce; beside reports of single cases or short series, there are very few large series and most of them are not recent (Meyer et coll., Yasuoka et coll., Guidetti and Spallone). The present report includes 230 cases of extramedullary tumors collected from 21 french departments over the last ten years (series of the French Speaking Society of Neurosurgery = S.N.C.L.F. series). Delimitation of what is called the F.M. region is rarely given in the literature. In this report, the inferior limit is put at the C2 level and the superior one at the ponto-medullary junction and the lower third of the clivus. To belong to the F.M. region, tumor must have its main part or its insertion within these limits even if it extends beyond them. On the contrary, if the gross development is out of these limits but with some extension into the F.M. region, the case is rejected. A chapter of this report deals with the anatomy of the F.M. with emphasis on the points useful for the management of the tumors. Some details are given on the dimensions of the different parts of the F.M. as given by anatomical studies and also by measurements on C.T. scanner and M.R.I. including during flexion and extension of the head. The S.N.C.L.F. series is then analyzed as a whole. It includes 106 meningiomas (M), 49 neurinomas (N), 28 chordomas (Ch), 32 osseous tumors (T.Os) (19 primary and 13 metastasis) and 15 cases considered as uncommon tumors. (T. Part.) (4 melanomas, 3 hemangioblastomas, 3 dermoid or epidermoid cysts, 2 ependymomas, 1 cavernoma, 1 angiomyolipoma and 1 cholesterin cyst). Mean age is 47 years, with a sex ratio F/M of 1.5/1. Duration of symptoms before diagnosis is of 27 months. Topography is classified into 3 groups anterior (70 cases), lateral (142 cases) and posterior (24 cases). A particular definition is given to these localizations, essentially referring to surgical difficulties and specially for meningiomas. The localization of a tumor is defined by the point of attachment to any structure (dura, spinal root, spinal cord); anterior tumors are attached to the F.M. on both sides of the midline; lateral tumors between the midline and the dentate ligament and posterior ones behind the dentate ligament. According to this way of classification, N are always lateral even if they present anterior or posterior extensions.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain Neoplasms↗
PubMed1990

Progressive necrosis of the conus medullaris: magnetic resonance imaging and surgical findings.

A 67-year-old man with non-insulin-dependent diabetes mellitus progressively developed, over a 2-year period, lower extremity sensory and motor defects associated with impaired bladder function and perineal and perianal sensation related to a disease of the conus medullaris extending from T12 to S5. The magnetic resonance imaging scan suggested myelomalacia and the diagnosis of progressive necrotic myelopathy was confirmed by surgical intervention.

Aged↗
PubMed1989

A rare embryologic variation: carotid-anterior cerebral artery anastomosis or infraoptic course of the anterior cerebral artery.

Carotid-anterior cerebral artery anastomosis constitutes an anomaly of the anterior part of the arterial circle of the brain. The anterior cerebral a. arises a few millimeters above the emergence of the internal carotid from the cavernous sinus, at the usual level of origin of the ophthalmic a. It travels medially, beneath the optic n., and then describes a curve with a superolateral concavity to arrive at the anterior part of the optic chiasma, where it anastomoses with the anterior communicating a. This asymptomatic variant of course is often associated with other cerebral vascular anomalies, especially arterial aneurysms. On the basis of 2 new cases discovered by chance, together with a review of the literature, various hypotheses capable of explaining the embryologic origin of these anomalies are discussed.

Adult↗
PubMed1989

Colloid cyst of the fourth ventricle: diagnostic problems and pathogenic considerations.

The authors report the case history of a patient with a colloid cyst of the 4th ventricle. The clinical history of slow intracranial hypertension, homogeneous hyperdensity with contrast enhancement on computed tomographic, scan, and the gelatinous aspect of the cyst at surgery are characteristic of colloid cysts. The diagnosis was made, however, only at the time of histological examination. A common neuroepithelial origin with 3rd ventricle cysts would be explained by similar embryological developments of the prosencephalic and the rhombencephalic roofs.

Adult↗
PubMed1989

[Otoneurosurgery in the elderly].

An oto-neuro-surgical experience on patients older than 65 years is reported. 25 patients have been operated: 9 meningiomas, 5 trigeminal neuroglia, 2 vestibular neurectomies, 9 acoustic neuromas. The assessment, the indication, the surgical techniques are discussed. Are also evaluated the anesthetic technique, the patient drugs, position, and the post-operative survey.

Aged↗
PubMed1988

[Microsurgical anatomy of the trigonoseptal region].

Eleven anatomical specimens were dissected under optical magnification in order to define the morphology of the trigone and septum, its ventricular choroid and vascular relations. These clearly explain ventricular development of tumors of this region and the importance of identification of venous structures in terms of surgical approach.

Cerebral Veins↗
PubMed1988

[Surgical approaches of the trigonoseptal region].

Surgical approaches to the trigone and septum are described with the help of dissections of anatomical specimens under operative conditions and using a microscope: the anterior frontal approach which gives access to the anterior pillars and to the body of the trigone; the ventricular junction route which provides an approach to the body of the trigone and to the hippocampal commissure; the anterior transcallosal approach.

Cerebral Veins↗
PubMed1988

[Petrectomy of the point during approach to the clivus: technic, values and limitations. Apropos of a case of meningioma].

A voluminous clivus meningioma was removed by a middle fossa transpetrous approach. We describe the surgical technique, with its advantages and its limits. The petrous bone was burred between the internal auditory canal, the internal carotid artery, the superior petrosal sinus and the inferior petrosal sinus. This approach gives excellent exposure of the clivus, anterior to the brainstem and the cranial nerves. This approach can be used for removal of voluminous intradural tumors arisen anterior to the internal auditory canal, and for clipping of aneurysms of the basilar artery. It appeared that the choice of the side for this approach must only depend on the extension of the tumour and displacements of the brainstem and the basilar artery, without concern on the hemispheric lateralization.

Aged↗
PubMed1987

[Embryology of the cerebral veins].

Formation of cerebral veins can be retraced through eight embryologic stages: before the 4 mm stage, neither arteries nor veins can be distinguished within the primitive network of the head; the 5 mm stage, when three dural plexuses can be identified; the 6 to 12 mm stage, marked by development of anterior dural plexus and lateralization of veins in relation to future cranial pairs; the 12 to 16 mm stage, with development of the anastomosis between anterior and middle dural plexus, and of the pial veins; the 16 to 21 mm stage, marked by regression of primitive sinus of the head and appearance of the anlage of straight sinus and of transverse and sigmoid sinuses; the 21 to 29 mm stage, with appearance of a temporary prosencephalic median vein, possibly implicated in the etiopathogenicity of so-called aneurysms of Galen's ampulla; the 40 mm stage with elaboration of the deep cerebral venous networks; the 60 to 80 mm stage during which the basal veins and Galen's ampulla are formed. After 3 months, the fetal encephalic venous system has attained its adult appearance.

Cerebral Veins↗
PubMed1987

[Microsurgical anatomy of the ampulla of Galen].

Anatomic study of 20 injected specimens dissected under operating microscope allowed evaluation of anatomic site of Galen's ampulla, venous confluents of Galen's ampulla, and internal cerebral veins' terminations and their arterial connections in this region. Findings demonstrated that even the wall of the great vein of Galen was supplied by arterioles, as though it was vascularized in the same way as durameter.

Cerebral Arteries↗
PubMed1986

[The place of arteriography in the etiologic diagnosis of spontaneous intracerebral hematomas].

456 cases of spontaneous cerebral hemorrhage have been referred at the Neurosurgical Department of the University of Rennes since the CT scan is available, i.e. from 1979 till 1984. Sixteen passed away at the time of admission itself. Among the remaining 440 cases a diagnosis of cerebro-vascular malformation was suspected in 189 according to some atypical features in clinical and/or scanographic presentation, but only 101 patients were actually submitted to an angiographic evaluation, 88 others presenting with a very deep comatose state leading to death in a few hours. We found 14 vascular anomalies (14 p. cent) amongst them eight arterial aneurysms, five arteriovenous malformations and one combining cerebellar AVM and arterial aneurysm of the basilar artery. We couldn't perform an autopsy in all lethal cases but the necropsy findings lead to discover eight additional cases (4 aneurysms and 4 AVM). Statistically it means that a gross vascular lesion is responsible of 5% of cases of cerebral hematomas (22 out of 440). We didn't take in account the cavernomas discovered at the pathological examination of the walls of several hematomas. We may conclude that a careful angiographic study is justified in following cases: young age of the patient (under 65); lack of risk factors, especially cardio-vascular or hematologic; relatively satisfactory clinical status of the patient; topographic criteria related to the CT scan (hematomas located in the fronto-basal area and near sylvian fissure).

Adult↗