9 Transsellar Approach

The transsellar endoscopic approach to remove pituitary adenomas represented the first application of the endoscopic technique to transnasal skull base surgery. ^{1 – 6} Subsequently, the same route was adopted for other rarer sellar tumors and tumorlike lesions. ^{7 – 10} This approach takes advantage of the natural corridor formed by the nasal cavities and sphenoid sinuses to approach lesions within the sella turcica through its anterior and inferior bony walls.

Different types of transsphenoidal accesses have been proposed in the literature, with the intent to minimize morbidity by precisely tailoring the sphenoidotomy to the need for cranial–caudal and medial–lateral exposure. ^{11 , 12} In line with this principle, submucoperiosteal–submucoperichondrial routes similar to those used for microsurgical resection of sellar lesions were developed to maximize the possibility of sparing nasal structures. ¹³ In summary, the basic concept is that the aperture of the sphenoid sinus should be tailored case by case, providing adequate exposure to safely and radically remove a sellar lesion.

As in general with endoscopic skull base surgery, the identification of bony landmarks is of utmost importance in transsphenoidal approaches. The transsellar corridor passes through the anterior and inferior sellar walls, whose boundaries are the tuberculum sellae superiorly, carotid prominences laterally, and clival recess inferiorly. Bony landmarks are not well evident in poorly pneumatized and/or multiseptated sphenoid sinuses. In fact, it is not infrequent that sphenoid sinus septa have a diagonal orientation inserting on the carotid prominence or sulcus, thus partially preventing a complete visualization of the sinus. More rarely, the sphenoid sinus can be poorly or nonpneumatized, thus requiring high expertise and possibly dedicated instrumentation (i.e., navigation and Doppler probe) to safely drill the sphenoid body to create an adequate corridor toward the sella.

The removal of the anterior and inferior sellar walls allows the exposure of the sellar periosteum. Within the sella, three planes of dissection in relation to the pituitary gland can be identified: the suprahypophyseal plane is enclosed between the pituitary gland and diaphragma sellae (this corridor can be considerably narrowed by arachnoid prolapse toward the sellar region or tumor expansion in the cranial direction); the infrahypophyseal plane guides toward the dorsum sellae and can be fully marsupialized toward the sphenoid sinuses by removing the sellar inferior wall; and the parahypophyseal plane lies between the gland and the medial wall of the cavernous sinus and is crossed in the inferior portion by the inferior hypophyseal artery. At surgery, these corridors of dissections within the sellar area are rarely required; however, their analysis in the anatomic laboratory can be helpful to fully understand the relationships of the sellar content with neighboring anatomical regions.

Related posts:

1 Classification of Endoscopic Transnasal Approaches to the Skull Base and Adjacent Areas 8 Transplanum–Transtuberculum Approach 17 Medial Transcavernous Approach 15 Transpterygomaxillary Approach 18 Lateral Transcavernous Approach 21 The Suprapetrous (Meckel’s Cave) Approach

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