The effect of variations in the subarachnoid pressure on the venous pressure in the superior longitudinal sinus and in the torcular of the dog

Abstract

Although Weed & Flexner [1933] have confirmed the earlier findings of Becht [1920] that the venous pressure in the torcular is uninfluenced by variations in the subarachnoid pressure, Wright [1938] has found that changes in venous pressure can readily be brought about by varying the subarachnoid pressure.He measured the venous pressure in the posterior part of the superior longitudinal sinus. A slight rise in the venous pressure was observed when the subarachnoid pressure was first raised; this, however, fell rapidly to a low level and remained there as long as the raised subarachnoid pressure was maintained. In another series of experiments, Wright [1938] studied the effect of a gradual rise in subarachnoid pressure on the rate of blood flow through the superior longitudinal sinus. A decrease in blood flow was observed when the pressure was first raised with a progressive reduction until complete cessation occurred, when the subarachnoid pressure exceeded the systolic arterial pressure. Astudy has been made in the following experiments of the effect of variations in subarachnoid pressure on the venous pressure in the superior longitudinal sinus and in the torcular of the dog. EXPERIMENTAL PROCEDURE Difficulty in obtaining dogs owing to the war conditions has made little selection possible; diseased and grossly undernourished animals, however, were always rejected. The subarachnoid pressure was measured with a needle in the cisterna magna. Variations in pressure were effected and maintained in the manner already described in earlier publications [Bedford, 1935[Bedford, , 1936. The highest pressure employed in these experiments was 500 mm. normal saline solution and the lowest 0 mm. normal saline solution. The venous pressure in the superior longitudinal sinus was recorded in the following way.

Cranial Venous Outflow Obstruction and Pseudotumor Cerebri Syndrome

“…In contrast Dixon & Halliburton [37] reported that increases in CSF pressure were accompanied by increases in torcular venous pressure. However, Wright [181] and Bedford [10] noted that increases in CSF pressure caused a small decrease in venous sinus pressure. This e¤ect was usually seen as CSF pressure was initially being increased and most likely represented a compressive e¤ect on the cerebral veins in the subarachnoid space and a decrease in venous return to the SSS.…”

Relationship between Intracranial and Sagittal Sinus Pressure in Normal and Hydrocephalic Dogs

“…When ICP is elevated by intraventricular infusion, the sagittal sinus pressure also rises but only a small amount compared to the elevation of ICP, thereby increasing the driving force for absorp tion of CSF into the sagittal sinus. Previously, most authors have reported no change or falls in sagittal sinus pressure when ICP is elevated; however, ICP was usually increased to unphysiologically high levels [1,15].…”

“…The several studies performed on animals have revealed contradictory results. Bedford [1] studied the effect of elevating the subarachnoid pressure on sagittal sinus pressure and torcular pressure in dogs. He found that a rapid elevation of CSF pressure to 500 mm H20 was invariably accompanied by a fall in both sagittal sinus pressure and torcular pressure.…”

“…Increases, decreases, and no changes in sagittal sinus pressure have all been reported when ICP is elevated [1,14,15]. The pressure differential between the cerebrospinal fluid (CSF) and sagittal sinus is important because it equals the driving force for absorption of CSF across the arachnoid villi into the sagittal sinus.…”

A comparison of ventricular fluid pressure and cerebral sinus pressure after a severe diffuse brain injury in the rabbit

“…With raised ventricular fluid pressure in dogs, the sinus pressure has been reported S. Valtonen : to drop (Wright 1938, Bedford 1942, Noell and Schneider 1948, rise (Shulman and Verdict 1967) or to remain the same (Beeht 1920, Weed andFlexner 1933). Similarly variable results have been reported for monkeys and baboons, a rise in ventricular fluid pressure coinciding with a drop in sinus pressure (Ryder et al 1951, Hedges et al 1964), a rise (Weinstein etal.…”