| Transcript |
We're going to talk about the kidney today,and not everything about the kidney,just what does a neuro-ophthalmology practice need to know about the kidney. So, as you know, the kidney is not just involved with filtering toxins. It's also involved in the blood pressure, and that is the renin-angiotensin system,and it can lead to hypertension because of renal vascular hypertension. It can also cause anemia,and that's usually related to both anemia of chronic disease, butal so the anemia that's from the decrease of erythropoietin and the red cell production. It's involved in the balance of electrolytes,the pH,and the water,and so that's the main function of the kidney that everyone's familiar with, and it's involved in calcium and vitamin D, and so you can get renal osteodystrophy and bone and calcium disturbances from kidney disease.And then it could be things that are related to the treatment of the disease, not the disease itself. And so,when people have chronic kidney disease, they can have decrease in their glomerular filtration rate,and that can affect us both in terms of the use of contrast material, in this case gadolinium for MRI, but also iodinated contrast in CT scan as well as end-stage renal disease related hemodialysis, which can produce intradialysis hypotension and lead to ischemic optic neuropathy and of course, patients have renal transplants; they can have immunosuppression and that leads to infections as well as the medicines themselves like tacrolimus, which can cause pseudotumor cerebri. So, we've got to worry about the normal function of the kidney,the things that the kidney does, diseases of the kidney,and side effects related to the treatment of the chronic kidney disease, including renal transplantation. And so,for the eye doctor,the things we need to know are if we have a patient who has loss of vision,we really have to bethinking about non-arteritic anterior ischemic optic neuropathy in a kidney transplant patient who has vasculopathic risk factors. You need to be worried about checking their blood pressure because it could be too high,malignant hypertension, and so we're going to looking at grade of their hypertensive retinopathy, and if it's grade three or four we should really be admitting that patient to the hospital, or it could be too low and that is intradialysis hypotension,which can precipitate ischemic optic neuropathy, both AION and PION, and we have to worry about papilledema, either from the medicines, tacrolimus and the other medicines. Steroids can cause what looks like secondary pseudotumor cerebri, or the papilledema might be from infectious etiologies like cryptococcal or other meningitis in a patient who is chronically immunosuppressed, and patients who have had end stage renal disease and are on hemodialysis might have a graft, an AV fistula, or an AV graft, and if that graft occludes,you might end up with increased intracranial pressure from venous back pressure. So, the graft can be placed in the brachial or the brachiocephalic and could cause a thrombosis, that or stenosis. The stenosis can cause retrograde venous flow up into the jugular leading to increased intracranial pressure,or the graft can thrombose, including superior vena cava occlusion-occlusive disease that can lead to increased intracranial pressure on the venous side,and those patients are particularly dangerous because they have normal image imaging of their head,they have a normal spinal fluid, but they have elevated open pressure,and thus they meet the modified Dandy criteria for pseudotumor cerebri on the idiopathic basis,but in a patient with kidney disease, you probably should not be giving diagnosis of IIH to a patient who has kidney disease. So, in summary, you need to know a little bit about the kidney,what it does normally, how it can affect us in neuro-ophthalmology, both on the afferent side in terms of ischemic optic neuropathy, malignant hypertension and hypertensive retinopathy, papilledema, either from increased intracranial pressure related to the drugs that are used for the renal transplant, or increased intracranial pressure from meningitis and the infectious complications of immunosuppression for the renal transplant,and the side effects of intradialysis hypotension in hemodialysis, as well as the problems that we sometimes see after grafts that have been occluded or stenosed. |
