04 Trans-Nasal Sphenoidotomy
Identify the sphenoid ostium by placing the endoscope and a straight suction instrument into the posterior choana and identifying the anterior face of the sphenoid bone.
The sucker can then be used to walk up the face of the sphenoid immediately adjacent to the nasal septum. The superior turbinate will then become visible. The usual location of the sphenoid ostium is one third of the way up the superior turbinate but can be extremely variable.
Alternatively, the ostium can be identified by placing the endoscope medial to the middle turbinate and identifying the superior turbinate. The ostium will be seen in the sphenoethmoid recess medial to the superior turbinate.
Using the small sucker, palpate the thick bone of the sphenoid face which then becomes soft as the fontanelle of the sphenoid ostium is approached. A small polyp, the presence of mucopus or a bubble of air may be clues as to the location of the sphenoid ostium.
It is always important to view the pre-operative CT scan to ensure there actually is a sphenoid sinus present. The sphenoid may be hypoplastic, lateral or even absent in rare cases.
Once the sphenoid ostium has been identified, it is then possible to enlarge it if required.
It is important to remember that the septal branch of the sphenopalatine artery passes just inferior to the natural sphenoid ostium. The safest way to enlarge the ostium is therefore laterally and superiorly although this needs to be performed with caution due to the optic nerve (laterally) and skull base (superiorly).