Virtual Mapping of the Frontal Recess: Guiding Safe and Efficient Frontal Sinus Surgery.

Objective To define relationships between the frontal sinus opening, ostia of other frontal recess cells, and endoscopic landmarks and to develop a clinically useful framework to guide frontal sinus surgery. Study Design Retrospective review. Setting Tertiary care academic referral center. Methods Adult patients with computed tomography (CT) without sinonasal pathology were included. Virtual endoscopy (using OsiriX) and corresponding CT reconstructions were used to identify all visible ostia in the frontal recess and characterize their positions in spaces between the uncinate/agger nasi (U), bulla ethmoidalis (EB), and middle turbinate (MT). Results Two hundred sides in 100 patients (median age 51 years, 62% female) were analyzed. The "center" of each map was defined as the intersection of spaces between U, EB, and MT. The frontal sinus opening was in the "center" in 53% of frontal recesses, lateral to this position in 29%, and anterior in 11%. When the frontal sinus opening was at the "center," anterior ostia drained frontal Kuhn T cells in 51% and intersinus septal cells in 23%. The skull base attachment of the apical strut of the uncinate process demarcated medial and lateral within the space between U and EB, with the opening to the frontal sinus medial in 68% and lateral in 31%. Left-right asymmetry in frontal sinus openings was noted in 46% of patients. Conclusion Combining preoperative imaging and knowledge of these anatomic relationships may facilitate more efficient frontal outflow tract identification and instrumentation. This represents the first and largest description of ostial configurations relative to endoscopic structural landmarks.

LEVEL OF EVIDENCE: 4.