| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (GP) Class of 2023, Baylor College of Medicine, Houston, Texas |
| Transcript |
So, today we're going to be talking about the neuro-ophthalmology of pregnancy, and in the pregnant state most of the problems that we see in neuro-ophthalmology are about volume and fluid shifts that occur during pregnancy, and also the hyper-coagulable state of pregnancy. So, those are going to be the three main mechanisms by which we're going to see changes in terms of vision loss or diplopia and other drop-down problems in pregnancy. So, the first thing is that pregnancy affects the entire visual pathway, and what that means is it can cause dry eye, defective tear film, it can affect the cornea and change the shape of the cornea, it can affect the lens and change the refraction. So, we really don't want to give pregnant ladies glasses or contact lenses while they're pregnant because it's likely to change. Once you get beyond the anterior portion of the eye, it can affect the middle part and the back part of the eye from the same mechanisms that we just discussed; blood flow problems and blood volume problems in the hyper-coagulable state, and so if it's an afferent problem then we're really worried about decreased vision in one or both eyes. That can be from an arterial occlusive vent like a branch or an artery occlusion. It might also be a central retinal artery occlusion or a branch retinal vein occlusion or a central retinal vein occlusion, and so we always want to be worried about the hyper-coagulable state of pregnancy and when patients have clots. In addition, those clots (the thrombosis) can produce pulmonary embolus and deep venous thrombosis, but for us in neuro-ophthalmology we're going to be concerned about cerebral venous sinus thrombosis, and that is going to present to us as increased intracranial pressure and the symptoms and signs of increase ICP by papilledema. So, in every patient who is pregnant who we think might have IAH you still have to be thinking about cerebral venous sinus thrombosis. That means MRI plus MRV, and most people would agree that an MRI scan without contrast is probably safe. The gadolinium is category C, which means there's some risk. I would talk to OB/GYN before doing any kind of MR study on this person. So, if we are not dealing with an arterial or venous sinus occlusive event, we can still have vision loss from stroke. That can produce homonymous hemianopsia or beyond on the efferent side with diplopia and nystagmus if it's a brain stem ischemic event, and we can have reversible events that are vascular and the most prominent are posterior reversible encephalopathy syndrome (PRES). PRES, which doesn't have to be posterior, doesn't have to be reversible and doesn't have to have encephalopathy is usually characterized for us as cortical blindness or homonymous hemianopsia with a bilateral hyper-intensity on the T2 and the flare. The differentiating feature is, as opposed to cytotoxic edema from stroke, the diffusion-weighted imaging will not show the restricted diffusion, so the DWI will be normal or it might just show shine through, and we need to correlate that with the ADC. The other reversible syndrome is the reversible cerebral vascular syndrome, which is vasoconstriction. So, when we have reversible cerebral vascular vasoconstriction, that can cause stroke and hemorrhage, including subarachnoid hemorrhage or intraparenchymal hemorrhage in pregnant patients.So, those are the reversible forms. Obviously, stroke may or may not be reversal, and so again with the DWI on a stroke we're going to see restricted diffusion. Both are going to show hyper-intensity to impress end stroke, but in stroke restricted diffusion. And, we have to worry about eclampsia and preeclampsia and that means checking the blood pressure is a super important part of any of these presentations, making sure it's not on the eclampsia/preeclampsia spectrum. We always want to consult OB/GYN. I'm going to be checking to see if the patient has proteinuria, as well as checking their blood pressure. So hypertensive changes can worsen during pregnancy and they can present with hypertensive urgency or hypertensive emergency. Likewise, diabetic retinopathy can worsen during pregnancy. Both the proliferative and the non-proliferative forms and that is associated with the comorbidity of hypertension. So, these two things together do sometimes get worse during pregnancy, so fluorescein angiography and OCT are useful in patients who are pregnant and who have vision loss in which we're worried about the retina, both looking at macular ischemia, proliferative disease and hypertensive retinopathy, hypertensive choroidopathy and hypertensive optic neuropathy. In addition, fluorescein and OCT might show fluid, and that can look like central serous retinopathy. Also, we want to check the blood pressure and look for preeclampsia in those patients. Some of those patients have HELP, which is hemolytic anemia, elevated liver function studies, and low platelets, and so the combination of the central serous retinopathy and PRES should really be making you think about the comorbidities and the overarching pregnancy related comorbidities of HELP and preeclampsia/eclampsia syndrome. In addition, some tumors grow during pregnancy because of the hormonal effects and that's pituitary lesions. The most classic is the Sheehan syndrome where the patient have acute bitemporal hemianopsia from pituitary apoplexy. Aneurysms also can grow or rupture during pregnancy related to the blood flow and blood volume. So, patients might have carotid cavernous fistula of the high flow type spontaneously because there's an intra-cavernous aneurysm that ruptured. You should also be thinking about aneurysm in the normal circumstances, like pupil involved third nerve palsy and the other ways that aneurysms come to us in neuro-ophthalmology. Because the blood flow and the blood pressure go up during pregnancy, the aneurysm might present during pregnancy. Finally, the other hormone-related and hormone-sensitive tumors, meningioma and schwannoma, can grow during pregnancy. A lot of the autoimmune disorders and uveitis and MS attacks seem to go down during pregnancy but after they deliver, the immune system which was suppressed during the pregnancy to keep you from attacking your baby turns back on all of a sudden, and so you might get a recurrent attack of autoimmune disease after delivery.So, in summary, the neuro-ophthalmic findings of pregnancy; you really should be thinking about pregnancy related changes across the entire visual pathway can affect the afferent or the efferent system. It's about blood flow, blood volume and the hyper-coagulable state of pregnancy. We want to be making sure in our papilledema patients that we did for cerebral venous sinus thrombosis, think about the reversible syndromes PRES and reversible cerebral vasoconstriction. Always measure the blood pressure and ask OB/GYN about proteinuria because preeclampsia/eclampsia can occur with any of these presentations. A fluorescein angiogram, OCT and a non-contrast MR are probably safe in pregnancy. For the fundus think about central serous and serous attachments in pregnant patients. |
