The absorption of cerebrospinal fluid into the venous system

Abstract

Resumen por el autor, L. H. Weed.La absorci6n del liquido cerebro-espinal en el sistema venoso.El presente trabajo ha sido llevado a cab0 con el control fisidbgico adecuado sobre las presiones del liquido cerebroespinal y las de 10s sistemas arterial y venoso intracraniales. El curso seguido por la absorcih del liquido cerebro-espinal bajo condiciones normales es a tmrav6s de las vellosidades de la aracnoides, penetrando en 10s senos venosos durales. Bajo la influencia de un aumento en el contenido salino de la sangre, producido por la inyecci6n intravenosa de una soluci6n fuertemente hipertbnica (ClNa .a1 30 por ciento), la absorci6n tiene lugar tambi6n por medio de 10s canales perivasculares y a travds del epitelio ependimario que tapiza 10s ventriculos cerebrales, hasta llegar a 10s capilares del sistema nervioso. En el proceso normal la filtracih puede ser el factor fisico de mayor importancia, pero despues de la inyecci6n intravenosa de soluciones hiperthieas muy fuertes, la 6smosis y la difusi6n juegan aparentemente el papel mits activo. Bajo condiciones normales no tiene lugar la absorci6n de materia particulada desde el espacio subaracnoideo y lo mismo sucede despues de la inyecci6n intravenosa de una soluci6n fuertemente hiperthica. TWO FIGURES AND FOUR CHARTSWith but few exceptions, all recent investigators of the processes of the cerebrospinal fluid have agreed that by far the major portion of the fluid is absorbed directly into the venous system and that only a very small portion escapes by way of lymphatic channels. Many of the observations upon which this conception is based have been of a physiological nature; the anatomical studies, fewer in number, have established in fairly definite fashion the exact pathways taken by this fluid in its return t o the blood stream. The general mechanisms, both anatomical and physiological, have thus come to be quite well understood though in many details uncertainty still exists. But now, because of more accurate technical procedures and because of certain physiological phenomenon reported during the past three years, new approaches to the investigation of the general subject of the venous absorption of the cerebrospinal fluid may be employed and it becomes possible to control, in more effective fashion, the experimental work.The writer in his first work on the absorption of this fluid ('14 a, b, c) made use of procedures which permitted control of many of the physiological factors concerned. In place of the customary aiiatomical method of injecting under high pressures viscous colloidal solutions or fatty substances into cadavers or dead animals, an isotonic, true solution of potassium ferrocyanide and iron-ammonium citrate was introduced into the subarachnoid space of living animals; the foreign salts were subsequently precipitated in situ as Prussian blue for histological study. In

The Diagnosis and Treatment of Spontaneous Cerebral Spinal Fluid Otorrhea in the Adult

“…AG are formed during development of the subarachnoid space as the primary method of CSF resorption into the venous system [8][9][10][11][12][13][14][15]. Normally they penetrate the dural wall of venous sinuses to lie within the vessel lumen.…”

Regional Diminution of von Willebrand Factor Expression on the Endothelial Covering Arachnoid Granulations of Human, Monkey and Dog Brain.

“…Since Weed's classic work [1] describing the role of arachnoid villi in the drainage mechanism of cerebrospinal fluid (CSF), many physiological and morphological studies on arachnoid granulation of many laboratory animals [2][3][4] and humans [5,6] have been reported.…”

Visualization of the cerebrospinal fluid drainage into the Galen's vein.

“…Since WEED (1923) proposed the arachnoid granulations or villi as the site of absorption of cerebrospinal fluid (CSF) into the venous system, it has been believed that the CSF drains into the superior sagittal sinus through them (LEVINE et al, 1982). This view has been applied even to lower mammals (MANN et al, 1979), although the arachnoid granulations appear later than does the CSF, both ontogenetically and phylogenetically (OSAKA et al, 1980).…”