The overall goal of this surgical intervention is to achieve a gross total removal of a pituitary adenoma through an endoscopic transnasal approach. The surgical technique facilitates the total removal of pituitary tumors to normalize hormone levels in separating tumors and to relieve visual and oculomotor symptoms in nonsecreting tumors. The main advantage of this technique is that it is minimally invasive while allowing maximum tumor resection, primarily due to the panoramic view that is provided by the endoscope.
There may be a learning curve for using the endoscope techniques for neuro-surgeons who have been primarily trained to perform with a microscope. After general anesthesia and oral tracheal intubation, with the patient in the supine position, position the head in a head holder and secure the band for the magnetic neuro navigation around the head. Identification of the sellar anatomy using known and landmarks, that's also confirmed by the neuro navigation, allows the tumor to be accessed within the sellar, the suprasellar cisterns, and the cavernous sinuses bilaterally.
Raise the head of the table to a 20 degree angle to improve the venous drainage. And slightly rotate the head about 30 degrees away from the side of the nasal fossa of interest while tilting the head in a contralateral direction. Sterilize the face with an alcohol-free chlorhexidine solution.
And clean the nasal fosse with an antiseptic solution. Wick away the antiseptic with a cotton pad soaked in Xylocaine supplemented with one percent adrenaline. Then clean the right abdominal quadrants and drape the abdomen, leaving a small window in the right periumbilical region.
When the patient is ready, introduce a short, rigid, zero degree endoscope into the right nostril to identify the inferior and middle turbinates laterally and the nasal septum medially. Place the endoscope tube either at the superior or inferior aspect of the nostril to provide enough space for other instruments entering the nasal cavity. Then, use a blunt spatula to gently and laterally retract the middle and superior turbinates to achieve a wide access to the ipsilateral sphenoid ostium.
To avoid bleeding from the nasal septal arteries, place a monopolar between the sphenoid ostium and the choanae to coagulate the nasal mucosa in vertical linear direction for about ten to fifteen milliliters. Next, use the blunt spatula to vertically open the coagulated nasal mucosa until a bony contact is felt. Follow the vomer anteriorly until it's junction with the nasal cartilaginous septum and push the mucosa to the contralateral sphenoid ostium.
Using bone forceps and a rongeur, expose and remove the sphenoid rostrum, extending the resection from one ostium to the other and exposing the exo cranial skull based surface. Gently remove the sphenoid mucosa if it interferes with the sellar opening. And use rongeurs to remove the sphenoid septum to provide a wide exposure of the sella turcica.
Identify the sella turcica anterior and superior to the clival recess in the midline and the lateral carotid prominences. Using a five milliliter large bone cutter, open the sellar floor to create a bone flap that may be repositioned at the end of the surgery. Then enlarge the sellar osteotomy laterally or anteriorly with bone rongeurs, according to the surgical target.
Use a micro-blade to open the selladurai as appropriate for the surgical target. And extend the dural open laterally as necessary, taking care to avoid any injury to the carotid arteries. This provides sufficient access to the sellar.
Using anular angled curets, forceps, and suction tips, remove the tumor tissue. After an intrasellar saline wash out, use a 30 degree angled endoscope to inspect the intrasellar space for any tumor remnants, particularly toward the cavernous sinuses. After removing the tumor from the sellar and the suprasellar cistern, it is essential to use 30 degree endoscope to visualize the tumor within the cavernous sinuses bilaterally.
If all of the tumor tissue has been removed, use saline irrigation and slight pressure with cotton pads to achieve hemostasis within the pituitary sella. Place a patch of bioabsorbable artificial dural substitute extradurally and reinforce the patch with a thin layer of surgical adhesive to reconstruct the durotomy. Replace the bone flap and secure it with more surgical adhesive.
Then confirm hemostasis of the nasal mucosa, particularly in the region of the naso central branches of the sphenopalatine arteries on both sides to prevent post operative epistaxis. And gently replace the superior and middle turbinates, in their original position, with a blunt spatula. Since 2009, this fully endoscopic, endonasal approach has been used to treat pituitary tumors with excellent post operative results on 473 patients with pituitary adenomas.
Most of the cases were non-functioning pituitary adenomas, followed by growth hormone secreting adenoma, and adrenocorticotropic hormone secreting adenomas. A total resection was achieved in 80 percent of patients with non-functioning pituitary tumors. Further, 30 to 100 percent of the patients who have undergone this procedure have demonstrated post operative chronological remission for up to seven years of follow up, depending on the type of tumor that was resected.
Once mastered, this technique can be completed in two hours, if it's preformed properly. While attempting this procedure, it's important to remember that good outcomes will depend on the precise understanding of the anatomy of the tumor in relationship to the rental skull base as viewed through an endoscope. After sufficient experience with the endoscope surgery of sellar tumors, this technique can also be extended to other under nasal approach like or clever cardoma surgery.
Don't forget that mastery of this technique requires practice in cadaver lab as well as many years of experience with surgery in live patients.
