Microadenomectomy for Cushing’s Disease
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Let's discuss the principles for resection of micro adenomas related to Cushing's Disease. This is a very young patient, a 20 year old female who presented with typical Cushing's disease, MRI evaluation revealed presence of a micro adenoma. More likely on the right side of the cellot. There was some question about presence of the tumor on the left side as well. You can see on the sagittal image, there is presence of a relatively sizable micro adenoma within the center of the tumor, again, toward the right side. Patient underwent an endoscopic endonasal trans sphenoidal resection on a tumor. Small osteotome was used to create a small bony window after which Carlson Ron Jours expanded the bony opening. These cases can be quite bloody. Venous channels are quite exaggerated and hypertrophied. An extended bony removal is mandatory from one cavernous sinus to the other and all the way anteriorly toward the tuberculum cellum. The celli is not expanded since it's not a macroadenoma and therefore the exposure can be quite limited. And therefore bony removal has to be expanded as much as safely possible. Any bleeding from the cavernous sinus is readily controlled using thrombic soaked gel foam or other hemostatic agents. Here's the extent of our bony opening all the way from one cavernous sinus to the other. I'm using stealth neuro navigation based on CT scan. The intro cavernous sinus is also apparent along the anterior edge of the dural exposure. Further bony removal extended more posteriorly, finally further hemostasis is secured, before I proceed with dural opening. Here's the final result. Immaculate hemostasis is mandatory before opening the dura so that microsurgery can be conducted within the gland using clear dissection planes, not obscured by the blood. The dure is opened in a cruciate fashion. Again, the dural opening has to be maximized as much as possible to alow careful and thorough inspection of the entire gland and all the edges of the walls of the cavernous sinus wall. I use it, an angled dissector to dissect the dura from underneath the gland. So the clan can be adequately inspected and residual tumor, not overlooked. We're just about ready to inspect the gland. On immediate or first inspection there is no evidence of a tumor, however, small incision within the middle of the gland reveals the tumor that is hiding within the heart or center of the gland. I'll go ahead and create a small cruciate incision within the gland as well so that the tumor can be carefully dissected and removed. Restricted incisions will compromise the ability of the operator to peripherally localize and dissect the tumor from the surrounding normal gland. Here's a piece of the tumor, very much yellow and discolored compared to the orange appearance of the normal gland. It's very important to note that if the gland is manipulator or compressed, it blanches, and it actually may look like the tumor, therefore the tissue should be inspected when the tumor is not manipulated. Here you can see the tumor versus the gland can be quite subtle at certain locations regarding which part is normal gland, which part is tumor. Here you can see their faint yellow color of the tumor. Now that the tumors debulked, I continue to inspect the resection cavity, again, immaculate inspection of the entire resection cavity is absolutely critical. As you can see, the piece of the tumor can be quite adherent to the normal gland. Part of their per tumoral area that contains normal gland may have to be removed as well. Now, the tumor is more exposed after a cap of normal pituitary gland was excised. Tumor is more suckable at this location. Piecemeal tumor removal is critical. I continue to work within the hidden or blind operative spots to deliver the tumor. One more time. It is absolutely mandatory to be able to inspect the inside of the gland, even if it takes to remove a cap of normal pituitary, to be able to improve operative visualization and see the differentiation between the tumor and gland a little bit more readily. One may say we're almost done with resection of the microadenoma however, the very careful inspection of the left side of the gland is also necessary, here no further tumor is visible. I'll go ahead and inspect the left side of the pituitary that may have not been effected by the tumor on the preoperative MRI. In other words, a negative MRI does not exclude the need for thorough and careful inspection of the entire gland. Hydroscopy, quite effective in inspecting the operative blind spots without any blood interfering with our visualization. I'm pretty satisfied with a resection on the right side of the gland. Some bleeding is controlled. Now you can see there's plenty of tumor on the left side of the gland could have been overlooked leading to sub optimal outcome biochemically after the surgery. So I'll go ahead and carefully inspect the latter aspect of the gland next to the wall of the cavernous sinus to exclude and remove the additional tumor. Here you can see a sizable piece of the tumor that is left around one o'clock. Angle endoscopes can be quite effective to look around the gland and remove the additional tumor that may not be readily visible using the zero angled endoscope. Hemostasis is further secured from the leaflets of the dura using bipoloroid cautery. Here's the use of the 30 degree endoscope to look just medial to the lateral wall of the cavernous sinus, the tumor can be quite tucked in and lodged in that corner. And its removal can be almost impossible until a direct view of the area is reached. I continue tumor removal until I'm able to see the lateral wall of the cavernous sinus. It's a small piece of the tumor that is adherent to the gland. Obviously this piece of the tumor has to be removed for a desirable outcome. I do not see diaphragma cella at this point. There is no evidence of CSF leakage. Here's further inspection, only normal pi twitter is apparent, accept in questionable small piece of tumor. As I mentioned a moment ago, compressing the gland during its operative, manipulation can lead to discoloration, temporary discoloration and blanching of the tissue, the normal tissue that can make the tissue to be confused with tumor. Let's go ahead and continue to inspect our operative cavity as much as possible. I don't see any residual tumor that is clearly visible. By now further inspection of the, again, that corner, just medial to the wall of the cavernous sinus revealed a small piece of the tumor that was overlooked. And this is a critical teaching point again, that every corner has to be very carefully inspected. Extra capsule, dissection is ideal. However it is not possible in all tumors, in all Cushing micro adenomas. Now that a small piece of the tumor was found this area, I'll go ahead and open the dura further and further inspect all the corners more thoroughly. Here you can see another piece of the tumor that I overlooked. Solid and gelatinous components of the tumor that are being removed, pi twitter and ron jours are effective for resection on a portion of the mass that's very adherent to the parenchymal of the gland. Now I can feel the wall of the cavernous sinus. The other piece of tumor was delivered. Let's go ahead and inspect this corner under direct vision in a moment. Further dural opening was mandatory for peripheral inspection of the lateral gutters. The normal gland is being mobilized. Don't see any other tumor in that corner, continue to expand our dural opening all the way, you can see the wall of the cavernous sinus. No, evidence of the tumor there, the walls have to be inspected. So complete tumor removal is confirmed. I'm pretty satisfied with the extent of resection, at least at this corner of the gland, here's the more posterior part of our resection cavity using the angled endoscope. I feel satisfied there that adequate tumor removal is accomplished, that small piece of the tumor that was questionable was removed using the three hand technique. In other words, there is a suction, a dissector, and a pituitary Ron jour at the same time within the nares to remove that very small piece of the tumor. That maneuver is specially critical and requires advanced familiarity with trans nasal endoscopic microsurgical techniques. Here's a, one of the final looks using hydroscope. Now on the left side of the client, inspecting the wall of the cavernous sinus, the pituitary gland and all the surrounding structures. This nice view is very unique when angled endoscopes are used, giving ample amount of confidence to the surgeon to remove the small piece of a tumor safely. And at the same time inspect the resection cavity. You can see now the lateral wall of the cavernous sinus on the right side, piece of fat wrapped in Surgicell was used to fill the resection cavity. Hemostasis was secured and the postoperative MRI revealed gross total resection of this tumor without any complicating features, thank you.
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