What are the 3 phases of a transsphenoidal surgery for a pituitary mass?

Three Phases of Transsphenoidal Surgery for Pituitary Mass

Transsphenoidal surgery for pituitary masses consists of three distinct operative phases: the nasal/sphenoid approach phase, the sellar opening and tumor resection phase, and the reconstruction/closure phase. These phases apply to both microscopic and endoscopic techniques, which are equally recommended for symptom relief in pituitary adenomas 1.

Phase 1: Nasal and Sphenoid Approach

This initial phase establishes the surgical corridor to reach the sella turcica:

• The surgeon accesses the sphenoid sinus through either a sublabial or endonasal pathway, with the endonasal route now preferred due to reduced nasal and dental complications 2.
• Optimal bony exposure of the sphenoid and sellar regions is critical during this phase, as adequate exposure directly improves the extent of tumor resection 1.
• The posterior sphenoid wall is opened to visualize the sellar floor, creating the working window for tumor access 3.
• Computer-assisted navigation may be used during this phase, though evidence is insufficient to formally recommend its routine use 1.

Phase 2: Sellar Opening and Tumor Resection

This is the definitive resection phase where the tumor is removed:

• The sellar floor is opened using drills or rongeurs to expose the dura, followed by dural incision to access the pituitary gland and tumor 3.
• Tumor resection proceeds with either microscopic or endoscopic visualization, with endoscopic approaches providing superior visualization of residual tumor, particularly in suprasellar and parasellar extensions 1.
• The extent of resection is maximized while preserving normal pituitary function, which is a primary surgical goal 3.
• Endoscopic visualization after initial microscopic resection frequently reveals residual tumor tissue, supporting the use of endoscopy for improved completeness of resection 1.
• Intraoperative MRI can improve gross total resection rates but is not recommended due to high false-positive rates requiring experience in interpretation 1.

Phase 3: Reconstruction and Closure

This final phase prevents postoperative CSF leaks and complications:

• When intraoperative CSF leak occurs (arachnoidal opening), a multilayer closure technique is employed: fat graft placed into the sellar cavity, followed by collagen sponge layer and fibrin glue 4.
• The sphenoid sinus is packed with fat graft and collagen sponge to provide additional support 4.
• External lumbar CSF drainage is maintained for 2-4 days when significant intraoperative CSF leak is encountered, reducing postoperative leak rates to approximately 1.5% 4.
• Despite various closure techniques being used in practice, there is insufficient evidence to recommend specific dural closure methods universally 1.

Critical Surgical Considerations

Hemodynamic monitoring throughout all three phases is essential to maintain cerebral perfusion while avoiding excessive bleeding, though "controlled" hypotension may have adverse effects 5.

For large tumors with significant suprasellar, frontal, or temporal extension, a combined transsphenoidal and transcranial approach should be considered rather than attempting complete resection through the transsphenoidal route alone 1.

Common Pitfalls to Avoid

• Inadequate bony exposure in Phase 1 limits tumor resection and increases residual tumor rates 1.
• Failure to recognize intraoperative CSF leak in Phase 2 leads to postoperative CSF fistula, with associated risks of meningitis and brain abscess 6, 4.
• Over-reliance on intraoperative MRI can lead to unnecessary additional resection attempts due to false-positive findings 1.
• Insufficient multilayer closure technique when CSF leak is present increases postoperative leak rates from the baseline 1.5% to higher levels 4.