The technical description of the transsphenoidal surgical procedure has been described elsewhere in detail (9,16). The main steps are reported here.
After general anesthesia, the patient is placed supine, with the legs slightly flexed, the trunk tilted 10°-20°, and the head turned 10° toward the surgeon and fixed in a Mayfield headrest without pins.
The endoscopic equipment (monitor, light source, video camera, video recorder) is positioned behind the head of the patient and in front of the operator who stands facing the chin in the position shown in diagram in Fig. 2A in Chapter 8. The fluoroscope C-arm or neuronavigation system are used as normal.
The nasal cavities are packed with gauze pledgets soaked in a diluted solution of 5% chlorohexidine gluconate, the face and the nose are prepared in the same way, and the patient draped.
The endoscope is introduced into the chosen nostril and cottonoids soaked with diluted adrenaline (1:100,000) or with xilomethazoline hydrochloride are placed between the middle turbinate and the nasal septum. These nasal decon-gestants, together with the controlled hypotension, minimize mucosal bleeding. After removing the cottonoids, the space between the septum and middle turbi-nate, if narrow, can be increased by gently mobilizing the head of the middle turbinate laterally.
The sphenoid ostium is the crucial anatomical point of the procedure because it is the entrance to the sphenoid sinus. It is extremely variable in shape, size, and position. It can be reached in several ways. The endoscope can be (1) introduced between the nasal septum and the middle turbinate, with a 30° angle with respect to the floor of the nasal cavity, or (2) inserted in the angle between the nasal septum and the floor of the nasal cavity until it reaches the choana. When the superior edge of the choana is identified, the endoscope follows the spheno-ethmoid recess for about 1.5 cm, between the superior turbinate and the nasal septum, until the natural sphenoid sinus ostium is identified. When reached, an endoscope holder is used to fix the instrument during the anterior sphenoidotomy and the next steps.
Once identified, the sphenoid sinus natural ostium is enlarged all around, using Kerrison's rongeurs or a microdrill, particularly in a downward and lateral direction, where bleeding from branches of the sphenopalatine artery can occur. The enlargement is completed with the removal of the sphenoid rostrum up to the contralateral ostium. Once the anterior wall of the sphenoid sinus is opened, the sphenoid septae can be identified and removed. The anterior wall of the sellar floor should now be recognizable, with the spheno-ethmoid planum above and
the clival indentation below. Lateral to the sellar floor the bony prominences of the intracavernous carotid artery and the optic nerve can be seen and between them the opto-carotid recess, shaped by the pneumatization of the anterior cli-noid process (Fig. 1).
The sellar floor, like the whole sphenoid cavity, is covered by mucosa, which is only displaced laterally if normal. It may be removed if abnormal or if infiltrated by the sellar lesion. How the sellar floor is opened depends on its thickness: if it is intact, entry is made by a microdrill with diamond burr; if it is eroded or thinned, it can be entered simply by means of a dissector. Once an opening has been made, it is enlarged with Kerrison's rongeurs and/or Stammberger circular cutting punch (Karl Storz, www.karlstorz.com).
The opening of the sellar floor must be extended as required, reaching, if necessary, the sphenoid planum above, the clivus below, and the carotid protrusions bilaterally.
The dura is incised in a linear or cross fashion. Curets and suction with slow and circular movements are used to remove large tumor fragments initially. The endoscope is then advanced into the tumor cavity for complete removal, followed by the dissection of the capsule, if possible. The Valsalva maneuver by
temporarily increasing intracranial pressure may be helpful in producing the descent of the residual tissue into view in cases of suprasellar expansion. The descent of the cistern is often seen at this stage of the procedure (Fig. 2), and a view of the optic chiasm or of the anterior part of the Circle of Willis can be obtained if the arachnoid is opened (11).
After tumor removal, if there is evidence or risk of a cerebrospinal fluid (CSF) leak, closure of the sella may be performed using a polyester-silicone dural substitute and fibrin glue (Fig. 3) (12) as described (13). This provides a barrier to the sphenoid sinus, reduces empty space, and prevents the descent of the chiasm into the sellar. If there is no leak, no repair is required.
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