| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (RK) Class of 2024, Baylor College of Medicine, Houston, Texas |
| Transcript |
So, today we're going to be talking about empty sella in neuro-ophthalmology. As you know, the empty sella can occur in just normal people and that might be as high as 15% of normal people just have what looks like that partially empty or empty sella. And what we're gonna concentrate today on is the secondary ones, not the primary ones, so you should know that that's a radiographic finding that we see on MRI scans of normal people incidentally that's a primary episode. The secondary empty sella occurs because the sella turcica-so that's "sella" and "turcica," it stands for "Turkish saddle." So this is the bone which houses the pituitary gland at the bottom of the saddle, and then the pituitary stalk, and then the chiasm is above that. So it's kind of like a little boat with the bottom of the boat being the sella turcica and the bone they've got the dorsum sellae behind it and the tuberculum sellae in front of it and the planum sphenoidale. So, when you have a lesion in the sella-an intrasellar lesion-it can grow and then come out of the sella and compress the optic chiasm. And so, the prototype for that intrasellar lesion with suprasellar extension is the pituitary adenoma, but there are other suprasellar lesions-meningeal, most craniopharyngiomas, et cetera, that can compress the chiasm and produce the typical thing which, in the book, is bitemporal hemianopsia, but you know, from a different lecture you can watch online, there are different visual field defects that occur in chiasm lesions. So, the usual secondary cause that we see is that you have some intrasellar mass with suprasellar extension like a pituitary adenoma that has been removed surgically like a transsphenoidal surgery. So after transsphenoidal surgery you'll get a secondary empty sella. It's empty because we took a big tumor out of it. The other way that you might see it is IIH. So when we have increased intracranial pressure, regardless of whether it's idiopathic or not, but IIH is just the most common thing that we see it within neuro-op. It pounds down on the poor sella and the pituitary again gets stepped on at the bottom and that's also a common radiographic finding of increased intracranial pressure, and most commonly for us that's the idiopathic intracranial hypertension. And that's why empty sella-a secondary empty sella-is one of the radiographic criteria that we use for defining Pseudotumor Cerebri or IIH. And the reason you need to know it in neuro-op is sometimes patients can have vision loss from this secondary empty sella, or they can have a pituitary dysfunction from this secondary empty sella syndrome. So, in patients who have had transsphenoidal surgery, sometimes they keep losing their vision, the bitemporal hemianopsia keeps getting worse, or their acuity is getting worse, or they've got an optic neuropathy, and you scan ‘em and the scan report comes back "stable post-operative change, secondary empty sella." But what we're really looking for is a distortion in the normal anatomy. So here's our normal boat with a normal sella and the normal pituitary at the bottom. If you have a big sella from sellar expansion from a tumor, you take out the tumor. Traction might start to occur at the bottom here. That traction pulls down on my chiasm, and, instead of it being a nice bar like this, it starts bending downward, and that same secondary empty sella can precipitate apoplexy or cause panhypopituitarism because the pituitary doesn't function well when it's being pulled or being pushed. So, the chiasm also doesn't function well. Usually it's being pushed by tumor, but sometimes being pulled by scar tissue. And that might respond to chiasmopexy-a surgery to push it back up. So, you need to know a little bit about empty sella. It can be primary and normal. It can be secondary from increased intracranial pressure, or can be secondary from a tumor that's been removed, and that secondary empty sella can lead to worsening visual loss or because worsening endocrinopathy and hormonal problems and the scan might be read as post-operative change but if it's pulling you might have to push it back up with a chiasmopexy. |
