Normal cerebrovascular physiology and vascular anatomy

The first part of this chapter describes normal neurovascular anatomy including its embryology, histology, and normal arterial variants. It includes angiographic arterial anatomy and also the structures and territories supplied by specific vessels. The anatomy of the venous sinuses and both the superficial and deep cerebral veins are described. The second part details normal cerebral neurophysiology, including autoregulation and the control of cerebral perfusion. It covers the myogenic, metabolic, and neurogenic mechanisms of cerebral blood flow and vessel diameter regulation. Finally, the role and influence of mannitol on cerebral blood flow is described, and how although it acutely reduces cerebral volume and intracranial pressure, its exact mechanism of action remains unclear.

URGENT DIAGNOSTICS OF CEREBRAL VENOUS TROMBOSIS

Investigations were carried out in 24 patients in order to evaluate information value of the data of clinical, laboratory, neuroradiological methods of research and develop the diagnostic algorithm in case of cerebral venous thrombosis (CVT). The main group consisted of 11 patients (7 male, 4 female, average age 49,1±4,3) with CVT. The comparison group included 13 patients (6 male, 7 female; average age 68,1±9,5) with ischemic stroke (IS) of moderate severity. There were revealed changes in blood and cerebrospinal fluid (CSF) as form of leukocytosis of blood and moderately increased cell count with elevated protein in CSF and blood in case of CTV. The authors noted an elevated protein in CSF and blood and leukocytosis with predominant lymphopenia in blood and neurophilic predominance in CSF within the reference range of CSF in patient with ischemic stroke. The epileptic attacks, meningeal syndromes, headaches were more often among clinical syndromes at CTV than in case of ischemic stroke. The algorithm of neuroimaging research methods and modes of MRI were determined and allowed an effective diagnostics of damages of venous sinuses, superficial and deep cerebral veins in case of urgent hospitalization of patients. It was possible to suggest the venous pathology in 7 (63,6%) cases due to SKT (without contrast) and in case of application of MR venography (2D TOFmode), there were revealed 100% of cases.

Falco-Tentorial Meningioma Producing Irreversible Midbrain Damage

Meningiomas arising from the falcotentorial junction are the rarest subgroup of tentorial menigiomas. Because of the distance from the brain surface and the surrounding deep cerebral veins these lesions are difficult and dangerous to treat surgically. A 45-year-old female presented with the history of progressive headache, disorientation, unsteadiness, and urinary incontinence for over 6 months. The patient developed difficulty in swallowing, and weakness of all four limbs for the last 7 days. CT scan brain plain and contrast showed a large well defined, homogenously enhancing mass lesion in the peineal region with compression of the upper brain stem and obstructive hydrocephalus. Inspite of the good surgical decompression the patient did not do well. As described in the literature, the compression of the midbrain can cause severe respiratory disturbances with fatal outcome; probably the similar mechanism resulted in poor outcome in present case. As we noticed the diffuse hypodensity in midbrain on CT scan, similar findings have been described in literature in cases of transtentorial herniation with poorer outcome.

Extra- and Transcranial Echo Colour Doppler in the Diagnosis of Chronic Cerebrospinal Venous Insufficiency

A new venous disorder, chronic cerebrospinal venous insufficiency (CCSVI), has been proposed in patients with multiple sclerosis (MS). It is a vascular condition characterized by an impaired cerebrospinal venous drainage due to obstructions in the main extracranial cerebrovenous outflow routes (i.e. internal jugular veins [IJV] and/or azygos veins). In this review, the studies which assessed the prevalence of CCSVI in MS by echo colour Doppler (ECD) will be discussed. The technical aspects of determination of the five CCSVI criteria: (1) reflux in the IJV and/or vertebral veins in supine and upright position, (2) reflux in the deep cerebral veins, (3) high-resolution B-mode proximal IJV stenosis, (4) flow not Doppler detectable in IJVs and/or vertebral veins (VVs) and (5) reverted postural control of the main cerebrovenous outflow pathway are described in detail. We conclude that so far there are many studies with contradictory results, and as yet a strong scientific base to support the evidence for a causative relationship of CCSVI and MS is lacking. Recent studies call into question the validity of using ECD as a proper and reliable test for the diagnosis of CCSVI. One explanation for the variety in interpretation of the individual CCSVI criteria, with the wide-ranging percentages CCSVI, could be the different methods by using ECD to determine various criteria.

Microsurgical anatomy of the great cerebral vein of Galen and its tributaries

Object. The deep cerebral veins may pose a major obstacle in operative approaches to deep-seated lesions, especially in the pineal region where multiple veins converge on the great cerebral vein of Galen. Because undesirable sequelae may occur from such surgery, the number of veins and branches to be sacrificed during these approaches should kept to a minimum. The purpose of this study was to examine venous drainage into the vein of Galen with a view to surgical approaches. If a vein hampering surgical access must be sacrificed, it can therefore be selected according to the smallest draining territory. Methods. The deep cerebral veins and their surrounding neural structures were examined in 50 cerebral hemispheres from 25 adult cadavers in which the arteries and veins had been perfused with red and blue silicone, respectively. Special consideration was given to the size and location of drainage of the vein of Galen and its tributaries. Conclusions. When a surgeon approaches the pineal region, several veins may hamper the access route. From posterior to anterior, these include the following: the superior vermian and the precentral or superior cerebellar veins, which drain into the posteroinferior aspect of the vein of Galen; and the tectal and pineal veins, which drain into its anterosuperior aspect. The internal occipital vein is the main vessel draining into the lateral aspect of the vein of Galen. It may be joined by the posterior pericallosal vein, and in that case has an extensive territory. To avoid intraoperative venous infarction, it is important to use angiography to determine the venous organization before surgery and to estimate the permeability and size of the branches of the deep venous system.