Computed tomographic analysis of frontal sinus drainage pathway variations and frontal rhinosinusitis.

Objective: The objective of this study was to radiologically determine frontal sinus drainage pathway variations with respect to superior attachment of uncinate process (SAUP) and their effect on prevalence of frontal rhinosinusitis.

Design: This was a retrospective cohort study.

Methods: Computed tomography scans of the 919 frontal sinus sides of 460 patients (252 female, 208 male; mean age, 35.1 ± 10.5 years) who were candidates for endoscopic sinus surgery were evaluated retrospectively between August 2012 and January 2013 by 3 radiologists to determine the SAUP types and the presence of frontal rhinosinusitis.

Results: The frontal sinus outflow tract was localized medial to the SAUP in 651 frontal sinus sides and lateral to the SAUP in 268 sides. We determined 3 types (types 7, 8, and 9) of SAUP in addition to 6 types defined in literature. The most common type of SAUP was type 3 (n = 332, 36.1%) followed by type 2 (n = 256, 27.8%) and type 7 (n = 160, 17.4%). Of the evaluated sides, 316 (34.3%) had frontal rhinosinusitis. Frontal rhinosinusitis was more common in the sides where the frontal sinus outflow tract was localized medial to the SAUP than those localized lateral (37.2% vs 27.6%, P = 0.006).

Conclusions: Endoscopic approach to frontal recess usually requires uncinectomy, and it is necessary to know SAUP to prevent postoperative retained superior portion of the uncinate process. The location of frontal sinus outflow tract on the SAUP affects the prevalence of frontal rhinosinusitis as well. Frontal rhinosinusitis is significantly more common when the frontal sinus outflow tract was localized medial rather than lateral to the SAUP.

Level Of Evidence: 2b.