Andy Lee, MD: Whats up, and welcome to yet one more version of the NeuroOp Guru. I am right here with my good good friend Elizabeth Fortin.
Elizabeth Fortin, MD: Hello.
Andy Lee, MD: And right this moment, we will be speaking concerning the comparability of the vary of lumbar CSF strain measurements in adults, each with regular CSF strain and an Idiopathic Intracranial Hypertension. So Elizabeth, perhaps you could possibly simply set the stage for us and inform us why will we even have to know this?
Elizabeth Fortin, MD: Yeah, so there’s been lots of change in our understanding of what the traditional CSF strain is. We used to make use of a a lot decrease higher restrict for the CSF strain, which was set at 20 in some unspecified time in the future. We realized that in all probability some regular people have increased ICPs than 20. So the with extra research, we raised that higher restrict to 25, and that is what we use at present in our tips to diagnose IIH. And it is vital for us, particularly in neuro ophthalmology, as a result of once we diagnose Idiopathic Intracranial Hypertension, the ICP raises one in every of our standards on prime of different issues, as you recognize, like optic nerve head swelling and different signs. We use this as one in every of our diagnostic standards, in order that’s why it issues for us to know, what’s the precise regular vary and in sufferers who haven’t got IIH.
Andy Lee, MD: And so this desk right here, Desk 1, has Group A traditional and Group B. And I see you’ve put a crimson field across the imply. Possibly you could possibly simply stroll us by these numbers and inform me what you suppose these imply to us as physicians.
Elizabeth Fortin, MD: I believe what’s fascinating in that desk is, to start with, in fact, the imply, offers you an concept of what usually our sufferers with regular CSF strain, what their CSF strain is round, so 18.7 for them. And group B is the IIH inhabitants the place it is a lot increased. So the imply was 37.7. The opposite fascinating half, in the event you go decrease, is the vary. The vary within the regular CSF strain group was 1 to 29.5. After which the group with elevated intracranial strain was 29 to, I believe it was to 66. So there’s a small overlap. And I believe we are able to have a look at the bar chart on the left hand facet. And that is additionally helpful as a result of it is very visible. So that you see that there’s an overlap between the traditional ICP inhabitants and our inhabitants of sufferers with Iron Age, however the overlap is kind of small as not less than in that examine. So on this examine, there was just one affected person within the regular ICP group that had a ICP increased than 29. And that was one worth of 30.5. And there was additionally just one affected person within the IIH inhabitants that had it a strain of under 30. In order that was fascinating to me to see how little the overlap was between the 2 teams. And I believe one power of that examine is that the lumbar punctures had been carried out by just one operator. So the identical expert operator was performing all of the LPs. And I actually suppose that that may have an effect on the reliability of the outcomes.
Andy Lee, MD: And so the little quote, right here is our outcomes due to this fact counsel warning, diagnosing IIH with CSF pressures under 30. Do you suppose that’s the right conclusion from these outcomes?
Elizabeth Fortin, MD: I believe, to me, my understanding of that examine is that, you recognize, typically we’ve got sufferers in whom we will we carry out a lumbar puncture. And the prognosis says isn’t apparent primarily based on simply the looks of the optic nerves and the signs and the findings on MRI. After which if we’ve got a strain between 25 and 30, then we would need to use warning with the prognosis and simply suppose that this may very well be a traditional ICP. Earlier than, we used to suppose that over 20 was an irregular or elevated ICP, and we all know that this has been consistently evolving over time. So I believe it is to be cautious with the ICP, and that the traditional may be increased than what we beforehand thought. I do not know what your interpretation of this could be.
Andy Lee, MD: Effectively, I form of view it like IOP. So ICP and IOP. however like glaucoma of the attention however like glaucoma of the mind. And so in glaucoma of the attention, we study that 20 quantity additionally, however 20 millimeters of mercury for the IOP like 20 centimeters in water for ICP. And what we realized I believe from glaucoma is there are those who have regular stress glaucoma, however they’re additionally those who have excessive strain which are ocular hypertensive, however they are not glaucoma, they’re simply glaucoma suspects. And I believe that is the identical factor right here, the place there may be two overlapping curves. Regular individuals who have excessive strain however nothing’s flawed with them, and individuals who even have papilla edema, however their strain is borderline, or they’ve clearly IIH and their strain is borderline. So to me, it is not a lot the quantity as it’s being cautious anytime we’re inside one customary deviation of the imply. And so to me, what this paper means is, in the event you get numerous let’s simply say the imply was 18.7, and also you add a normal deviation of 5.2. And also you’re speaking about to watch out for numbers within the 23 to 25 vary, as a result of that is just one standarddeviation from the imply. And meaning you could possibly be regular individuals or one customary deviation and the imply, however there’s nothing flawed with them. And I believe the identical factor applies the opposite method, which is 37 was their imply, however their median was 35, and a normal deviation of 8. So, in the event you take 35 and you’re taking away 8, you are speaking about 27 or 28, one thing like that. And so meaning a few of these individuals with 27s nonetheless have it. So, for me, it is not concerning the quantity 30, which they selected. I believe we’re nonetheless in the identical ballpark of what we use. We’re used to twenty to 25 being borderline. And by borderline, what you imply is one customary deviation from the imply. Twenty-five and above is like an IOP of 26. You are like, Okay, that is in all probability glaucoma, however there’s some people who find themselves two customary deviations from the imply, and so they nonetheless haven’t got glaucoma. And so I believe this helps add as much as make the quantity that we’ll settle for, increased somewhat than decrease. I do not suppose it adjustments what I do by way of sensible if the individual appears to be like like papilledema. I am nonetheless going to deal with that even when the strain is borderline. However it’s helpful to have some numbers and I believe it is a fairly fascinating factor, as you talked about, and that the road appears to divide it at 25 to 30. Someplace in there may be the place the crimson and the blue within the left hand panel are seeming to overlap. And meaning we will over diagnose some individuals, however we might underdiagnose some individuals if we put the quantity 30 there.
Elizabeth Fortin, MD: Precisely. And we’ve got to keep in mind that in actual life and our LPs are going to be carried out by totally different individuals. And typically you possibly can lose some fluid whenever you put the manometer on and so, you recognize the proper approach isn’t would not, you recognize, actually apply to actual life. So I believe I utterly agree that with like with any prognosis, we’ve got to make use of our medical judgment. And now we simply know that perhaps you recognize, the upper restrict of regular may be a little bit greater than what we thought however I do not suppose it’ll change my observe both.
Yeah, so I all the time inform the residents deal with the affected person, not the quantity. And we deal with individuals not pressures. However it’s a fascinating factor, and I thanks on your time once more, Dr. Fortin. And this concludes yet one more version of the NeuroOp Guru. We’ll see you once more subsequent week.
Elizabeth Fortin, MD: Sure, thanks.