http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:11524 Object: In the majority of adults with idiopathic intracranial hypertension (IIH), there is an elevation in venous pressure associated with a venous outflow stenosis. In about 15% of IIH patients the elevated venous pressure is associated with an elevation in blood flow but little or no evidence of a stenosis. Venostenotic IIH and idiopathic hydrocephalus in children with a normal blood inflow have been shown to be equivalent. The aim of this study was to test whether children with hydrocephalus and an elevated arterial inflow have a vascular pathophysiology that is analogous to the hyperemic form of IIH in adults. Methods: Nine children with idiopathic hydrocephalus underwent MR imaging with flow quantification and were found to have arterial inflows 2 SDs above the mean for normal controls. Measurements of the head circumference, ventricular enlargement, total blood inflow, superior sagittal sinus (SSS)/straight sinus (SS) outflow, and the degree of collateral venous flow were performed. The results were compared with findings in 14 age-matched controls. Results: In hyperemic hydrocephalus the cerebral blood inflow was elevated but the SSS and SS outflows were in the normal range. The sinus outflow as a percentage of the inflow was reduced by 8 percentage points in the SSS territory and 5 percentage points in the SS territory compared with findings in the controls (p = 0.04, p = 0.003, respectively), suggesting blood was returning via collateral channels. Conclusions: Similar to patients with hyperemic IIH, children with hyperemic hydrocephalus show a significant elevation in collateral venous flow, indicating that the same venous pathophysiology may be operating in both conditions. 2012-09-13T05:44:23.106Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8353 Object: A collapsible segment in the venous outflow has been noted in many patients with idiopathic intracranial hypertension (IIH). Mathematical modeling has shown that these collapsible segments can account for the elevated cerebrospinal fluid (CSF) pressures associated with IIH. However, the model required an elevated outflow resistance of up to 10 times normal to predict the CSF pressures actually found clinically. Measurement of blood flow in patients with IIH has shown that inflow rates vary, with higher rates noted in patients with lesser outflow stenoses. The aim of this work was to extend a simple model of cerebral hydrodynamics to accommodate a collapsible sinus and elevations in cerebral blood flow in accordance with in vivo measurements. Methods: Forty patients with IIH underwent MR imaging in which the degree of stenosis on MR venography was compared with the total blood inflow by using MR flow quantification. The relative outflow resistance in IIH was estimated using the CSF opening pressure. The patients were compared with 14 age-matched control individuals. Results: Patients were divided into 3 groups based on MR venography appearances (minimal stenosis, stenosis of 40–70% and > 70% stenosis). In vivo measurements suggested a relative resistance elevation of 2.5 times normal, 4.2 times normal, and 4.8 times normal in the 3 groups, respectively. There was an increased inflow of 1.56 times normal, 1.28 times normal, and 1.19 times normal in these groups. Conclusions: The model correctly predicted the CSF pressures noted in vivo, suggesting that high arterial inflow is required for patients with low-grade stenoses to be symptomatic. 2011-07-20T02:00:08.638Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:4326 I read with great interest the paper entitled “Reversibility of Venous Sinus Obstruction in Idiopathic Intracranial Hypertension” recently published in the American Journal of Neuroradiology by Rohr et al. This paper presents the case histories of 3 patients with idiopathic intracranial hypertension (IIH) and venous outflow stenoses. I believe that the assertion by Rohr et al that placement of a stent should not be offered to patients who have IIH and collapsible stenoses is not necessarily correct. The only proviso is that the stent must support all of the compliant sections of the venous system or the stenosis will recur. Ultimately, whether the front-line treatment of IIH associated with collapsible venous outflow is stent placement orshunt insertion will depend on the relative morbidity of these procedures and their long-term rates of success. 2010-04-27T05:08:01.661Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:4328 A reduction in the proportion of the arterial inflow drained by the superior sagittal sinus in idiopathic intracranial hypertension (IIH) patients without stenoses has been noted and this has suggested elevated collateral flow. This study defines the interaction between arterial inflow and venous outflow in patients with outflow stenoses and IIH. Forty patients with clinical IIH underwent standard MRI, MR venography and MR flow quantification studies of the cerebral arteries and veins. There were 21/40 patients with venous stenoses. The arterial inflow was 21% higher than normal (p = 0.01); however, the superior sagittal sinus outflow was normal, giving a reduced percentage of venous outflow compared to inflow. Seven patients were followed up after remission of their symptoms and the arterial inflows and percentage outflow returned to normal. There is a spectrum of findings in IIH; patients with stenoses have lower inflows than those with patent sinuses but still have evidence of collateral flow. 2010-04-27T05:07:55.657Z ]]>