Transsphenoidal hypophysectomy is a commonly used surgical approach for pituitary region masses, with many significant advantages over open craniotomy.
The transsphenoidal approach was first described in 1907 by Schloffer, modified by Halstead and subsequently popularized by Harvey Cushing, who is most associated with this technique . It is interesting to note that towards the end of his career Cushing abandoned transsphenoidal surgery in favor of a subfrontal approach .
Transsphenoidal surgery is indicated in many pituitary region tumors, including:
- pituitary adenomas
- craniopharyngiomas (provided they are intrasellar)
- biopsy of midline sphenoclival lesions (e.g. chordoma, aspergilloma, meningioma etc.)
- debulking of larger tumor
It is important to note that the size of the suprasellar component is not terribly important, and tumor can be delivered down into the pituitary fossa from as high up as the foramen of Monro . This can be aided by Valsalva maneuver or introduction of air or sterile saline via a lumbar drain.
The main limitation of the transsphenoidal approach is that the operative corridor is narrow and lateral tumor is difficult to resect. As such tumors with large parasellar components should be tackled transcranially if a total resection is being aimed for .
It is beyond the scope of this article to go into operative details, and only a brief summary is provided, at a level useful to a radiology audience .
- general anesthesia
- patient is placed semi-sitting in Mayfield tongs
- intraoperative fluoroscopy is used to confirm instrument positioning
- operative microscope is used
- incision in the buccal mucosa under the upper lip
- blunt submucosal dissection along the nasal septum to the sphenoid sinus
- speculum inserted
- anterior wall of the sphenoid sinus is opened
- mucosa of the sphenoid sinus is removed from the posterior wall
- anteroinferior wall of the pituitary fossa is opened
- the dura is opened
- tumor is removed with a variety of instruments (e.g. pituitary rongeurs)
- the surgical defect is packed with fat
- anterior wall of the fossa reconstituted with bone/cartilage/glue etc.
- further fat packing
- nose is packed with petroleum jelly (e.g. Vaseline) gauze impregnated with bacitracin ointment
- lip incision closed
Recently endoscopic techniques have also been developed.
- postoperative hemorrhage presenting similarly to pituitary apoplexy
- CSF leak which may result in meningitis