Chair of Neurosurgery, Medicomilitary Academy, Saint Petersburg, Russia
Surgical Technique
Fig.1. A general view of the Polystar-2 universal rentgenologic C-arm system (Germany), ensuring lateral fluoroscopy in transsphenoidal removal of pituitary adenomas.
As a rule, a cavity of the sphenoid sinus turned out to be open after resection of rostrum sphenoidale.
However, an opening on the anterior wall of the sinus (3-5mm) was insufficient for further manipulations. A butt end of the endoscope, introduced through this narrow opening, became flooded with blood. It demanded its repeated extraction from the operative wound and cleaning. As a result, there was considerable increase in operation duration.
Opening of the sphenoid sinus was performed with the help of Luk's forceps or the chisel. Then it was widened with Hajek's forceps and/or the chisel.
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Fig.4. Endoscopic landmarks of the sphenoid sinus: |
The endoscope was inserted into the sinus cavity for providing its panoramic view. The most important landmarks of the sinus were determined; the saddle fundus and projection of its median line were verified (Fig.4).
The first important endoscopic landmark was a medial wall of the sphenoid sinus (intersinus septum), visualized after sphenoidotomy in the majority of cases. It was absent only in 2-4% of our cases. The sinus septum looked like a bone plate, whose both sides were covered by mucosa, lining the sphenoid sinus cavity.
It should be noted, that a form, localization and thickness of the septum varied.
Usually it ran along a midline (or nearly it) from the anterior wall of the sphenoid sinus up to the saddle, dividing the sinus cavity into two halves. However, the septum deviated from its initial position and ran to this or that side in almost 45% of cases. Thus, the sphenoid sinus consisted of two unequal parts, one of which was much bigger in some cases. Such anatomic localization of the septum resulted in the following: it ended at convexities of the ICA and optic nerves.
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Fig.5. Anatomic versions |
Additional septa were watched in 20%. They divided the sphenoid sinus into 2-3 segments partially or completely (Fig.5).
Removal of the median intersinus septum was performed in the majority of cases for good visualization of the sinus cavity. In case of its considerable deviation from a midline and localization out of the fundus projection, only initial segments of this septum were resected.
Additional septa of the sinus were removed, when they passed via the area of the saddle fundus in a place of supposed trephination and hampered orientation in the sinus cavity.
The second important landmark in the sphenoid sinus was convexity of the saddle fundus. A panoramic view of the sphenoid sinus after resection of the intersinus septum allowed to watch and to identify it rather easily. This structure looked like a round or oval eminence and was localized in the posterior one third of the sinus upper wall. The saddle fundus was limited by planum sphenoidale from above, which could be visualized in all cases; there was no dependence on a type of pneumatization of the sphenoid sinus. Convexities of ICA, optic canals and opto-carotid recesses were localized on both sides. The lower part of the fundus continued with excavation, corresponding to Blumenbach's clivus, in the area of the sinus posterior wall (Fig.4).
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