| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (SE) Baylor College of Medicine, Houston, Texas |
| Transcript |
So today I'm going to talk to you about how important the Sellais. It's called the Sellaturcica. This means Turkish saddle, and the reason that's important is a Turkish saddle looks different than a western saddle. Here in Texas, that'd be a cowboy saddle but it's Turkish saddle is meant for comfort not for roping and that means it's very deep so in the Sella we have a front part followed by a flat part. This is called the planum sphenoidale. There's a bulge right before you get to the flat part which just looks like a tuber like a potato like tuberculosis. This is the tuberculum sella, and then the back part which is the dorsal part is the dorsum sella, and then that slopes on down to the clivus. So, we have the anterior part of the saddle, the deep Turkish part of the saddle, and the posterior dorsum part down the ski slope to the clivus, so when we have the clival lesion, it can be contiguous with the Sella, and what lives in the Sella is your pituitary gland. However, this view, the sagittal view, is just one way of looking at this; you also have to know what it looks like in coronal view. So, in coronal view the cavernous sinus is on either side of the Sella. The internal carotid artery lives inside the cavernous sinus, and in the wall of the cavernous sinus are the cranial nerves three, four, five subdivision one, posteriorly five subdivision two, and in the substance of the cavernous sinus cranial nerve six, the Horner's pathway (oculosympathetic pathway)is also inside here on the carotid onto a short course on six, and then five subdivision one. This is the cavernous sinus but notice that you can have a lesion in the Sella that can just jump right into the cavernous sinus. So, normally when you have a pituitary lesion, it goes the path of least resistance. The least resistance is to just go straight upstairs, and from the pituitary to the chiasm is about 10 millimeters, and so it just goes straight upstairs and hits the body of the chiasm. This is why the most common presentation of a pituitary lesion is a bitemporal hemianopsia from the crossing chiasm fiber denser superiorly because you're pressing from below. So, the common Sellar presentation is bitemporal hemianopsia denser superiorly. However, sometimes the tumor decides not to take the path of least resistance which is just to go straight upstairs but to go into the cavernous sinus, and if it goes into the cavernous sinus, that causes double vision, not loss of vision. That double vision can be third, fourth, sixth; it could be with or without anisocoria, big pupil if its third, small pupil if there's concomitant Horner'ssyndrome,v1 or v2 pain in the face. So, if the Sella lesion goes into the cavernous sinus: ophthalmoplegia. I fit goes upstairs: bitemporal hemianopsia. If it hits the junction of the optic nerve and chiasm that's the junctional scotoma, either the junctional scotoma of Traquair, a monocular hemianopic field defect, or the junctional scotoma a central loss plus a contralateral superior temporal field defect. Looks like this, and the junctional scotoma looks like this: a normal field and a monocular hemianopic field defect. Or if it hits the tract, you'll get an incongruous homonymous hemianopsia, and what that means is a Sellar lesion pretty much could come to me in neurop with any of the neurophthalmic complaints that you could possibly think of. It could be loss of vision in one eye. It could be loss of vision in one eye and be hemianopic the junctional scotoma of Traquair. It could be bitemporal hemianopsia. It could be the junctional scotoma regular version. It could be homonymous hemianopsia. Any pattern of visual loss could still be Sellar, and if it chooses to go into the cavernous sinus any pattern of ophthalmoplegia, third, fourth, sixth, with or without oculosympathetic Horner's syndrome, with or without trigeminal dysfunction, and the most common scenario that we see this acutely is hemorrhage. And so if the pre-existing pituitary adenoma hemorrhages, then it can rapidly go right into the cavernous sinus and that condition is called apoplexy, so you need to be aware that normally a pituitary tumor is benign and presents to us with slowly progressive symptoms but it can occur acutely in the acute setting that's apoplexy. An acute bitemporal hemianopsia is easy, that one of course is apoplexy, but the harder one is when the apoplexy jumps into the cavernous sinus and presents with ophthalmoplegia that could still be apoplexy, and so you need to know a little bit about the imaging and that this is a Sella but it's a Turkish saddle very deep and you can go upstairs, or it can get laterally. |
