Hirsch was the first to adopt the endonasal route to the sphenoid sinus using multiple-staged operations including resection of the middle turbinate and ethmoidectomy [43]. Despite his success, however, he changed his technique to a transseptal approach. Almost eight decades later, in 1987, Griffith and Veerapen revived the endonasal approach to the sphenoid sinus [44].

The patient is placed in the supine “reflex” position with the knee and body slightly bent at the mid-position to prevent entrapment neuropathy, venous pooling, and patient slippage (Fig. 27.3). The head is slightly tilted to the contralateral side, the neck is flexed, and the head is extended at the occipitocervical joint and slightly turned toward the surgeon. This ensures that the face is parallel to the floor and places the sphenoid ostia in the direct line of sight of the surgeon. The head may be fixed in a three-point Mayfield frame or on a horseshoe head holder and secured with tape. At least 10 min prior to incision, the nostrils are packed with oxymetazoline-soaked cottonoids to allow shrinkage of the turbinates and to optimize hemostasis during initial exposure. We no longer routinely prep the nose. The ipsilateral thigh or abdomen is prepped and draped for harvest of fat and fascia. Some surgeons use intraoperative C-arm fluoroscopy for guidance; however, we prefer to use such assistance only in selected cases. The rostrum of the sphenoid is identified at the level of the superior aspect of the distal middle turbinate with direct vision using a handheld speculum. The sphenoid ostium is found as the superior landmark of the opening of the rostrum just at the level of the inferior border of the superior turbinate. The perpendicular plate of the ethmoid is fractured at the junction of the sphenoid rostrum. A self-retaining nasal retractor is placed with the remnant of the perpendicular plate of the ethmoid in the midline. The mucosa are elevated away from each side of the sphenoid rostrum. The sphenoid ostia should become visible, and the sphenoid rostrum is removed with the aid of micro rongeurs or a high-speed drill. The sella is identified, and the bone over the sella is removed with micro rongeurs. A #11 blade is used to create a durotomy in an X-fashion, and then small, angled microscissors are used to further open the dura to the extremes of exposure desired (Fig. 27.4). With large tumors, the intracranial pressure helps deliver the tumor when the dura is opened. First, the floor of the tumor is removed with curettes. Then, the lateral aspects of the tumor are removed to enable descent of the large center part of the tumor. Four-quadrant curettage with various Hardy ring curettes allows further tumor removal from lateral, superior, and inferior recesses. Closure begins with packing the resection site with adipose tissue. The septum is reduced to the midline, and the authors elevate the middle turbinates on both sides to ensure unimpeded drainage of the maxillary sinuses. The authors employ well-lubricated, soft, curved Rhino Rocket tubes covered with a piece of latex as airway tubes, which are carefully placed posteriorly into the nasopharynx [45, 46].

The successful reintroduction of the pure endonasal route paved the way for the use of endoscopic surgery in addressing sellar and suprasellar lesions [47, 48]. There are many advantages to the employment of endoscopy as a sole or supplemental tool for the resection of pituitary lesions. The endoscope provides a panoramic view of the sphenoid sinus and its important bony impressions. It also affords the surgeon with the ability to zoom in on areas of interest such as the tumor–gland interface and obtain a sharpened close-up view. Lenses of various angles on the endoscope allow the operator to look into anatomic corners of the suprasellar region that otherwise cannot be seen with the conventional microscope. Additionally, there is no displacement of the midline septum, and nasal packing and retraction are not needed [49–52]. Notwithstanding the improved and versatile visibility afforded by endoscopic transsphenoidal surgery, the technique is not without pitfalls. In general, more of the nasal septum is resected to allow adequate visual access. With endoscopic surgery, the surgeon’s field of view is reflected on a screen as a two-dimensional image, which results in loss of the sharp and focused stereoscopic view and depth perception provided by the microscope. In addition, there is a steep learning curve for the neurosurgeon inexperienced in endoscopy [53–55]. In our hybrid practice, we have been increasingly employing the endoscope as a supplemental tool for inspecting areas that are hidden from the field of view of the microscope in all of skull base surgery. In lateral and extreme anterior and posterior tumor rests, and those that are buried behind redundant folds of suprasellar arachnoid as well as in cases of tumor extending into the cavernous sinus, the endoscope is a valuable tool.

The standard transsphenoidal approach is used in most cases of pituitary tumors with sellar and suprasellar extension; however, regions of the skull base that were once thought only accessible “from above” are now being approached transfacially. With better knowledge of microsurgical anatomy and modern microinstrumentation, neurosurgeons have modified the transsphenoidal approach to gain better access to regions such as the cavernous sinus and the suprasellar cisterns.

Fraioli et al. [56] treated 11 patients with sellar tumors invading the medial wall of the cavernous sinus with a transmaxillosphenoidal approach, which involves a unilateral, bilateral, or Le Fort maxillary osteotomy and removal of the medial wall of the maxillary sinus in addition to the standard transsphenoidal exposure. It allows direct visualization of the intracavernous carotid artery during tumor resection but is limited by extension of tumor lateral to the carotid artery. Sabit et al. [57] described a safe, minimally invasive combined transmaxillary transsphenoidal approach to the cavernous sinus that is both extradural and extranasal. This approach provides adequate lateral-to-medial reach in the parasellar and infrasellar regions with visualization of the entire ipsilateral cavernous sinus and the medial aspect of the contralateral cavernous sinus. The extended transsphenoidal approach to tumors of the tuberculum sellae and suprasellar cistern was first described by Weiss [58]. Suprasellar tumors without sellar enlargement have been successfully resected using a modified transsphenoidal approach that involves a wide bone exposure of the anterior surface of the sella and removal of the posterior portion of the planum sphenoidale [59, 60]. This novel approach has allowed resection of craniopharyngiomas, central nervous system hemangioblastomas, and ectopic ACTH-producing adenomas arising from the pituitary stalk [59, 60].

Additional exposure of the skull base for lesions of the parasellar and clival region can be achieved by extended transsphenoidal approaches [36]. Various portions of the skull base may be exposed, and bone resection can be extended by repositioning the patient’s head and the self-retaining speculum. The standard transsphenoidal approach can be extended anteriorly to resect suprasellar lesions, inferiorly to expose clival lesions, and inferolaterally to access cavernous sinus lesions (Figs. 27.5, 27.6, and 27.7) [36]. These variations on the transsphenoidal approach provide a minimally invasive technique that avoids prolonged surgery and brain retraction.

Technological advances in the areas of endoscope-assisted microneurosurgery [47, 49] have been applied to the classical transsphenoidal operation in an attempt to further decrease morbidity and mortality risks [47, 52, 55]. Jho and Carrau [52] reported encouraging results in a series of 50 patients who underwent endoscopic endonasal transsphenoidal surgery. One of the main advantages of this approach is excellent panoramic visualization of the sellar and suprasellar anatomy with increased illumination and magnification [48]. Anatomic studies have demonstrated that the endoscope provides a volume of exposure superior to that of the operating microscope [54], but disadvantages include the lack of stereoscopic vision, the lack of adequate instrumentation, the limited space of working through one nostril [49], and a learning curve for using this technique.