| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (DZ) Baylor College of Medicine, Houston, Texas |
| Transcript |
"So, what we're going to talk about today is venous sinus stenosis in pseudotumor cerebri or idiopathic intracranial hypertension (IIH). As you know, in IIH you have these criteria-the modified dandy criteria: your symptoms can only be from increased intracranial pressure, your signs, which are capital edema and sixth nerve palsy, can only be from increased intracranial pressure, and the radiograph, preferably an MRI with an MR venogram, can only show increased intracranial pressure that's flattening the globe, empty sella, fluid in a sheet, tortuous vessels and venous sinus stenosis. So, venous sinus stenosis is one of these radiographic findings and the lumbar puncture can only show elevated intracranial pressure but a normal CSF count. These are the modified dandy criteria. So, today we're going to talk about whether you think this is the chicken, or is this the egg, and what that means is does venous sinus stenosis cause idiopathic intracranial hypertension or does increased intracranial pressure cause venous sinus stenosis? And the reason it's important is, as you know, you've got the superior sagittal sinus, transverse sinus, transverse sinus, sigmoid down the jug. The most common location for the venous sinus stenosis is at the junction of the transverse sinus and the sigmoid sinus, and so at that bend, there's turbulent flow and so there's often signal drop out right as it's making that bend, and it's thought that that stenosis and that turbulent flow is what causes the symptom of pulse synchronous tinnitus. They hear the whooshing sound created by the turbulent flow as the flow is going past that stenotic segment. And so, when we think about whether it's the chicken, that is, could this thing cause what we call idiopathic intracranial hypertension? The reason it's important is if that's the cause and you have a venous sinus pressure gradient like 9 or 10 Torr across the stenotic segment, then putting a stent, a rigid construct across that stenotic segment, could cure idiopathic insurance hypertension, if it's the cause. And that has been done, a lot of places do do the stent. For me, I require that you have a pressure gradient. We have to have the venous sinus stenosis. You have to have no other findings except for the modified dandy criteria, and ideally, we would do a spinal tap and it wouldn't open. So, if the spinal tap lowers the intracranial pressure and the thing doesn't open up well then, maybe that's good evidence that that's the cause, rather than the egg. Alternatively, if the high pressure increases your cranial pressure, presses on the compressible vein, and it just presses at the most accessible compressible part, the distal transverse sinus, then that means increased ICP causes venous sinus stenosis and not the other way around. The stent people would say it doesn't matter whether it's the chicken or the egg, because putting the rigid construct across this will open the outflow and will help it regardless of whether it's the chicken or the egg. The stent will create new flow pattern and will allow the CSF to drain and the ICP to drop. And so, you need to know a little bit about venous sinus stenosis. It's still controversial, whether it is the chicken or the egg. The stent people would say it doesn't matter because you're opening it up. However, the strongest evidence, in my opinion, against it being the cause of the problem is that it doesn't explain the other features of IIH, which are the female gender, the age predilection, and the weight. These things suggest it is multifactorial, and so maybe there is an anatomic factor that is a predisposing and then there's a precipitating factor. I don't believe this is going to be solved anytime soon and that's why idiopathic intracranial hypertension remains idiopathic." |
