Transsphenoidal Hypophysectomy

Excerpt

For decades, the central skull base has been a challenge to surgeons, given its inaccessible location. Pituitary surgery or hypophysectomy has evolved over the last century from open surgery, requiring craniotomy, to a fully endoscopic endonasal procedure through the sphenoid sinuses. The transsphenoidal approach was described and popularised in 1910 by Harvey Cushing and Oskar Hirsch, utilizing sublabial and transnasal routes, respectively. Though the popularity of the transsphenoidal approach went down when Cushing abandoned it for transcranial approaches, it was preserved by Dott, Guiot, and refined by Hardy, who introduced microsurgical techniques.

Approaches to the pituitary gland can be broadly classified into transcranial and extracranial approaches. Transcranial microscopic approaches, used currently in cases where transsphenoidal approaches are contraindicated, involve anterior subfrontal and pterional (frontotemporal) approaches. Pterional approach, which involves removing the sphenoid wing and minimal brain retraction, provides the shortest trajectory to the parasellar region and excellent visualization of the pituitary gland. An anterior subfrontal approach has the advantage of straight visualization of the pituitary tumor between the optic nerves. But it is less popular compared to the pterional approach because of potential damage to olfactory nerves and frontal sinuses.

Extracranial approaches primarily consist of transsphenoidal microscopic approaches (transnasal or sublabial) and endoscopic transnasal transsphenoidal approach, along with modifications such as expanded endoscopic endonasal approach (EEEA) and combined transsphenoidal transmaxillary approach. Transsphenoidal microscopic approaches used the sublabial or septal incisions, followed by a wide dissection of mucoperichondrium/mucoperiosteum of the septum and floor of the nose along with partial resection of the vomer, the perpendicular plate of the ethmoid, and the sphenoid rostrum. The nasal contents are pushed laterally with a self-retaining speculum, allowing the use of an operative microscope and bimanual instrumentation. However, this technique was associated with significant morbidities, such as facial swelling and pain, regular need for nasal packing or septal splints, etc. Sinonasal complications such as sinusitis, numbness of the upper alveolus, nasal synechiae, and septal perforation were common. First described by Jankowski in 1992, endoscopic pituitary surgery uses the natural medial nasal corridor to assess the sphenoid sinus. It has gained popularity over transsphenoidal microscopic approaches due to its shorter hospital stay, panoramic view, and good mobility with angled views. Endoscopic transsphenoidal hypophysectomy has revolutionized the field of minimal access to skull base surgery and opened doors to extended anterior skull base approaches.