Figure 1: Harvey Cushing abandoned transsphenoidal surgery in approximately 1929 as his transcranial techniques progressed and were deemed safe. The transcranial route allowed him to more thoroughly decompress the chiasm. In these photos, Cushing demonstrated his classic “frontal” incision for resection of pituitary adenomas.

Figure 2: Pituitary macroadenomas are larger than 10 mm in diameter and demonstrate mass effect on the surrounding structures. Their compression is most clinically evident as bitemporal hemianopsia from mass effect on the chiasm and/or optic nerves.

Figure 3: The configuration of a typical pituitary adenoma on a sagittal plane is shown here. Note the location of the compressed pituitary gland in the posterior or superior directions.

Figure 4: This young patient with a giant off-midline asymmetrical macroadenoma underwent surgery via an expanded transnasal endoscopic approach (upper images). The lateral and posterior parasellar components were not easily resectable through the transnasal route because of the tumor’s consistency and a “blind” lateral operative reach. Suprasellar tumor decompression was accomplished, but significant postoperative residual tumor continued to cause mild optic apparatus and brainstem compression, limiting the efficacy of radiosurgical therapy (lower images). A pterional craniotomy was deemed appropriate to further decompress the optic nerve and brainstem. During the second surgery, the tumor was debulked and the nerves decompressed but capsule was found to be very adherent and was left behind to protect the perforating arteries.

Figure 5: When wide bony removal at the sellar floor is complete, the exposed dura, including the intercavernous sinus, is gently cauterized using bipolar electrocautery. I use an ample amount of FLOSEAL hemostatic matrix (Baxter, Deerfield, IL) to seal the bleeding from the cavernous sinus and other venous lakes within the exposed dura. Overcoagulation of the dura leads to its shrinkage and exacerbation of epidural venous bleeding.

The principle of judicial minimalism in bone removal, while not compromising adequate lesional exposure, microsurgery, and tumor removal, is pertinent. The most common cause of subtotal resection is inadequate bone removal and resultant restricted dural opening. I create a wide bony opening along the floor of the sella, encompassing the walls of both carotid arteries.

Before dural opening, a circumferential bony edge should be mucosa-free to allow reconstruction of the floor at the end of the operation. Ultrasonography may be used to guide the dural opening and avoid injury to the carotid arteries. The dura is incised in a cruciate fashion, and a round dissector is used to widely dissect the tumor capsule from the inner surface of the dura. This maneuver expedites identification of the tumor capsule during the later stages of the operation when tumor debulking will make the capsule less identifiable (Redrawn from Tew, van Loveren, Keller*).

Figure 6: The first step of macroadenoma resection involves a sequential debulking procedure. The inferior pole of the tumor is punctured and morcellized by a ring curette; suction removes the dislodged tissue. A standardized approach to tumor debulking is encouraged and should begin inferiorly, then posteriorly, laterally, and finally superiorly. This sequence prevents premature descent of the diaphragm and its interference with tumor manipulation. Early exposure and descent of the diaphragm can obstruct the operator’s view for radical tumor removal and places the diaphragm at risk of tearing.

The central portion of the tumor should be avoided early due to the risk of applying downward traction on the diaphragm, thereby masking the lateral aspects of the adenoma. The superior aspect of the tumor should be cautiously manipulated because of the risk of injuring the pituitary stalk (Redrawn from Tew, van Loveren, Keller*).

Figure 7: Debulking should continue into the lateral aspect of the tumor, ending at the superior segment. After generous debulking, the tumor capsule is gently peeled off from the walls of the cavernous sinus. The angled endoscope allows a more expanded view of my operative maneuvers so that I can dissect the tumor capsule away from the medial walls of the cavernous sinus under direct vision rather than blindly searching for the lateral poles of the tumor using ring curettes. The location of the normal pituitary is ghosted in orange in this illustration. Note the use of a bimanual dissection technique (Redrawn from Tew, van Loveren, Keller*).

Figure 8: The medial wall of the cavernous sinus should be scrutinized carefully to remove any remaining tumor. This is a crucial step; residual tumor will prevent the later descent of the diaphragm and radical tumor removal. The direct line of sight of the microscope will not allow adequate visualization of these lateral corners. Blind aggressive maneuvers can lead to an injury to the carotid artery. For a discussion regarding management of carotid artery injuries, refer to the chapter on Pituitary Adenoma: Diagnosis and Operative Considerations.

In the event that the tumor invades the medial cavernous sinus wall or the diaphragm, intracavernous and supradiaphragmatic resection can be continued, but pursued cautiously. The endoscopic-expanded perception using angled endoscopes promotes conservative removal of tumor within the cavernous sinus under direct visualization (Redrawn from Tew, van Loveren, Keller*).

Figure 9: Upon resection of the infrasellar portion (especially the lateral components) of the adenoma, caudal prolapse of any suprasellar portion of the soft adenoma into the sellar compartment facilitates additional tumor removal. Fibrous or septated tumors (especially recurrent tumors) can resist this prolapse, making their removal challenging. Direct endoscopic visualization allows safe intrasellar sharp dissection of the septations.

In these situations, injection of 15 to 20 ml of lactated Ringer’s solution or air into the lumbar drain (placed preoperatively for giant tumors,) compressing the jugular veins bilaterally, and administering positive end-expiratory pressure can also assist with tumor mobilization. Patience is a virtue here as tumor descent is gradual. “Removing what the tumor gives you” rather than pulling indiscriminately on the blind corners is the safest strategy.

Following resection of this portion of the tumor, the diaphragm is visualized prolapsing into the sella. This is a good indication for adequate resection, but further inspection is necessary. If the diaphragm is not readily collapsing, there is usually residual tumor along the lateral aspects of the resection cavity preventing the descent of the diaphragm. Bony exposure may need to be expanded laterally and additional tumor removal secured in these regions. Blind reach is not recommended (Redrawn from Tew, van Loveren, Keller*).

Figure 10: The anterosuperior portions of the adenoma provide a challenge during their resection because of the risk of damaging the adjacent structures, most commonly the diaphragm. This is another common location for unintentional subtotal tumor removal; the residual tumor can continue to cause symptomatic optic apparatus compression. Angled endoscopes provide superior visualization in this region. The gland may be gently mobilized to expose residual tumor. Adequate bone resection is required to avoid residual tumor (Modified and Redrawn from Tew, van Loveren, Keller*).

Figure 11: A tear within the diaphragm and resultant cerebrospinal fluid leakage often occurs during blind forceful removal of a tumor located along the anterior aspect of the resection cavity above the tuberculum sella (anterior sellar recess) where the diaphragm is attached (inset image). It is important to identify the diaphragm and maintain its integrity throughout resection. If an inadvertent leak is apparent, I pack the previously prepared fat globules from the patient’s abdomen at the exact location of the leak and avoid indiscriminately and forcefully packing the entire sella because this maneuver may lead to suprasellar mass effect and vision impairment (Modified and Redrawn from Tew, van Loveren, Keller*).

Figure 12: I use abdominal fat graft for packing the sella after transsphenoidal surgery. The fat globules are wrapped in pieces of Surgicel to create spheres. This method facilitates their handling and directs their insertion/placement at the exact site of the leak. If Valsalva maneuvers exclude a leak, I still gently pack the sella to seal an occult leak. A piece of bony septum or prosthesis is used to keep the fat in place and reconstruct the sella floor. See the epidural location of the bone or prosthesis in the above illustration.

If a large defect in the diaphragm is created and the suprasellar contents are visible, a nasoseptal pedicled mucosal flap is prepared, and reconstruction is performed according to the procedure described in the chapter on Endoscopic Expanded Transnasal Approach (Modified Redrawn from Tew, van Loveren, Keller*).