**8.1 Introduction**

Gerard Guiot is recognized as the first neurosurgeon to use the endoscope in the transsphenoidal approach, although he abandoned the procedure because of inadequate visualization [74, 75]. In the late 1970s Apuzzo, et al. [76], as well as Bushe and Halves [77, 78], resurrected the application of endoscopes as a technical adjunct in the microscopic extirpation of pituitary lesions with extrasellar extension. Application of endoscopes was started initially to augment microsurgery, allowing the visualization of structures that were out of the line of vision; a view that were acquired with angled mirrors by other surgeons [75, 79]. Axel Perneczky, introduced the use of the endoscope in intracranial neurosurgery. He emphasized that endoscopic appreciation of micro-anatomy which may not be appreciated with microscope and pioneered the concept of minimally invasive neurosurgery [9, 80].

In the early 1990s, the pure endoscopic transsphenoidal technique was introduced as a result of the collaboration between neurological and otorhinolaryngological surgeons. In 1992 Jankowski and coworkers from the Central Hospital of the University of Nancy shared the experience of 3 cases of pituitary tumor in which they carried out a pure endoscopic transsphenoidal approach [81].

More recently, with other technical adjuncts such as neuronavigation and microvascular Doppler ultrasonography, endoscopic transsphenoidal surgery has been extended to the treatment of lesions outside the sella turcica, introducing the concept of extended approaches to the skull base [82, 83].

#### **8.2 Operative procedure**

The patient is intubated under general anesthesia, in supine position with the trunk elevated 100 and the head turned 100 towards the surgeon and fixed with three pin or tape in a horse-shoe headrest. Some surgeons prefer to fix with 3 pin rigid fixation and some do not; navigation is possible either way. Just before entering with the endoscope, the nasal cavities are packed with pledgets soaked in a diluted adrenaline. Some surgeons prefer cocaine or a mixture of cocaine and adrenaline. The operation can be divided in the following 3 phases.

#### *8.2.1 Nasal phase*

On entering with the endoscope, the main anatomical landmarks can be identified, such as the nasal septum medially and the inferior turbinate laterally (**Figure 13**). Following the tail of the inferior turbinate with the endoscope, choana can be reached, that is limited medially by the midline marker, vomer and, superiorly, by the floor of the sphenoid sinus.

The middle turbinate is gently pushed laterally to enlarge the virtual surgical corridor between the nasal septum and the middle turbinate. For a greater passage, some surgeons prefer to break and take the middle turbinate out, which can easily be avoided by lateralizing the turbinate. Looking upward with the endoscope, it is possible to identify the sphenoid ostium, usually located approximately 1.5 cm above the roof of the choana. If the sphenoid ostium is covered by either the superior or the supreme turbinate, these can be gently lateralized or removed, protecting the lateral lamella of the cribriform plate on which they are inserted. The removal or the lateral luxation of these turbinates should be done with extreme care in order to avoid ethmoidal plate injuries resulting in cerebrospinal fluid (CSF) leak.

**Figure 13.** *Nasal stage of endoscopic pituitary surgery.*

### *8.2.2 Sphenoid phase*

To avoid arterial bleeding from septal branches of the sphenopalatine artery, the sphenoid phase of the procedure starts with the coagulation of the spheno-ethmoid recess and the area around the sphenoid ostium. The nasal septum is detached from the sphenoid rostrum by means of a microdrill. Subsequently, the anterior wall of the sphenoid sinus is widely opened with microdrill and Kerrison punches, proceeding circumferentially, with a caution not to overextend the opening in the inferolateral direction to avoid the damage to the sphenopalatine artery or its major branches.

It is important to widely expose and open the anterior face of the sphenoid to allow a proper working angle for the entire instrument when inside the sphenoid with their tips in the sella. After the removal of all the sphenoid septa, the posterior and lateral walls of the sphenoid sinus, with the sellar floor at the center, the spheno-ethmoid planum above it, and the clival indentation below, become visible. The bony prominences of the intracavernous carotid artery, the optic nerve and, between them, the optico-carotid recess can be visualized lateral to the sellar floor (**Figure 14**). The bony protuberances of the intracavernous carotid artery should be recognized to define the sellar floor boundaries, though the bony landmarks may not be properly identified in all cases. The superior and inferior intercavernous sinuses should be identified, bearing in mind that there are variations in anatomy and number of the intercavernous sinuses.

The sphenoid sinuses were classified into conchal, presellar and sellar types (there is also a description of mixed types) initially by Hammer and Radberg [84], a widely accepted classification as it can predict the surgical corridor used in transsphenoidal surgeries. Guldner *et al.* subdivided the sellar type into incomplete and complete types that were based on the extension of the pneumatization beyond the posterior wall of the sella [85, 86]. The modifications and the traditional system focus on the posterior extent of pneumatization and the ease of accessibility of the sellar floor during endoscopic endonasal resection.

**Figure 14.** *End of sphenoidal phase of the pituitary surgery. The sellar floor is seen.*
