International Frontal Sinus Anatomy Classification (IFAC)

The International Frontal Sinus Anatomy Classification (IFAC) (Wormald 2016) is used to classify frontal sinus cells.¹
It was developed as an alternative to prior classification schemes such as the Kuhn Classification which were felt to be insufficient in describing the number and position of cells and how they affect the frontal sinus drainage pathway.
It also further extends upon the recommendations from the European Position Paper (EPOS) on the Anatomical Terminology of the Internal Nose and Paranasal Sinuses (2014)², which suggested classifying frontal cells as either anterior or posterior, and medial or lateral, depending on their relationship to the inner walls of the frontal sinus.
In the IFAC system, cells are classified both based on their relationship to the walls of the frontal sinus and recess (anterior, posterior, medial), as well as how far they extend into the frontal sinus.

Cell Name	Definition
ANTERIOR CELLS	Pushes the drainage pathway of the frontal sinus medial, posterior, or posteromedially
Agger nasi cell (ANC)	Cell that either sits anterior to the origin of the middle turbinate or directly above the most anterior insertion of the middle turbinate to the lateral nasal wall.
Supra agger cell (SAC)	Anterolateral ethmoidal cell, above the agger nasi, that does not extend into the frontal sinus.
Supra agger frontal cell (SAFC)	Anterolateral ethmoidal cell above the agger nasi that extends into the frontal sinus.
POSTERIOR CELLS	Pushes the drainage pathway anteriorly.
Supra bullar cell (SBC)	Cell above the bulla ethmoidalis that does not extend into the frontal sinus.
Supra bullar frontal cell (SBFC)	Cell above the bulla ethmoidalis that extends into the frontal sinus.
Supraorbital ethmoid cell (SOEC)	Anterior ethmoid cell that pneumatizes around the anterior ethmoidal artery over the roof of the orbit.
MEDIAL CELLS	Pushes the drainage pathway laterally.
Frontal septal cell (FSC)	Medially based cell of the anterior ethmoid or the inferior frontal sinus, that is attached to or located in the interfrontal sinus septum.

Wormald, Peter‐John, et al. “The international frontal sinus anatomy classification (IFAC) and classification of the extent of endoscopic frontal sinus surgery (EFSS).” International forum of allergy & rhinology. Vol. 6. No. 7. 2016. ↩
Lund, Valerie J et al. “European position paper on the anatomical terminology of the internal nose and paranasal sinuses.” Rhinology. Supplement vol. 24 (2014): 1-34. ↩

Last updated October 15, 2022