Authors of section


Nicolas Homsi, Paulo Rodrigues, Gregorio Sánchez Aniceto, Beat Hammer, Scott Bartlett

Executive Editors

Edward Ellis III, Eduardo Rodriguez

General Editor

Daniel Buchbinder

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Endoscopically assisted transnasal drainage

1. Introduction

Endoscopic sinus surgery techniques can be used to open the frontal recess from below.

This procedure is commonly performed by surgeons with experience in endoscopic sinus surgery.

endoscopically assisted transnasal drainage

2. Transnasal drainage

Frontal recess exposure

Resect the agar nasi cell and the anterior ethmoid air cells. The dissection is carried superiorly to circumferentially expose the frontal recess from below.


FR: frontal recess
OS: ostium sphenoidalis
MT: middle turbinate
NS: nasal septum
C: Choana

endoscopically assisted transnasal drainage

Frontal sinus trephination

Frontal sinus trephination may be helpful for identification of the frontal sinus ostia. If the ostia is not completely blocked, irrigation of the sinus from above will reveal fluid drainage endoscopically from below. This can help define the location of the true ostia.
Intraoperative navigation can also be helpful in localizing the true ostia.
The surgeon must be aware that the skull base anatomy may be distorted secondary to the trauma.

endoscopically assisted transnasal drainage

Resection of septum

After isolation of the first sinus ostia, carry the dissection across the septum/midline. Use a scalpel and shaver to resect the superior 2-3 cm of the septum.

endoscopically assisted transnasal drainage

Enlargement of right frontal ostia

Enter the frontal ostia with a drill removing the nasal crest of the frontal bone. Move anterior and medially towards the contralateral ostia. Enlarge the true ostia to completely resect the nasal crest, expose the anterior skull base (posteriorly), and the medial orbital wall (laterally).

endoscopically assisted transnasal drainage

Enlargement of left frontal ostia

Use a similar technique to drill out the left frontal ostia.

frontobasal sinus outflow disease

Resection of sinus floor

Drill across the midline to join the left and right sinus ostia. Remove as much bone as possible anteriorly and medially to enlarge the drainage pathway. Use caution when drilling posteriorly (skull base) and laterally (orbit).

endoscopically assisted transnasal drainage

3. Aftercare following endoscopic management of skull base corrections

General postoperative care

  • Postoperatively, a period of a supine bed rest (1-2 days) is necessary with the trunk and head raised 30°.
  • Use antibiotics in the perioperative period.
  • Patient follow-up after discharge. The patient is seen 4 weeks and then every 3-6 month in the first 2 postoperative years.