Morphometric study of fixed nasal anatomical structures related to endoscopic surgery of sinuses and anterior base of skull in hemisagittal cadaveric heads

Abstract

Background : Endoscopic sinus and anterior skull base surgery requires anatomical landmarks to identify the location of each paranasal sinus. Even though many anatomical reference points are applied, they can be distorted by tumors, inflammatory processes and previous surgeries. An earlier study of the paranasal sinus in computed tomography found that the maxillary roof (orbital floor) represented a reliable fixed anatomical landmark during
the endoscopic dissection for the entry of the sphenoid sinus that avoids the skull base. However, the study in cadavers has never been performed and no comparative study between genders has been done.

Objective : To determine the distance from nasal floor to cribriform plate, ethmoid roof, skull base, sphenoid floor and the orbital floor. A comparison between genders was carried out.

Methods : Thirty-nine hemisagittal Thai cadaveric heads were included in this study. Four parameters were measured as follows: the nasal floor to the lowest point of cribriform plate (A): the nasal floor to the highest point of ethmoid roof (B): the nasal floor to skull base at the anterior wall of sphenoid sinus (C): and the nasal floor to the floor of sphenoid sinus (D). The distance from the nasal floor to the highest point of the maxillary roof or
orbital floor (E) was measured after removal of the lateral nasal wall.

Results : Twenty female and nineteen male hemisagittal heads from 39 cadavers were included in this study. The mean distances of A, B, C, D, and E were: 44.1  4.4, 49.1  4.7, 45.6  5.1, 20.6  3.2, and 32.4  3.8 mm,
respectively. The results revealed that the mean distance from the nasal floor to orbital floor (E) was the shortest among those of A, B and C. All orbital floors were lower than the cribriform plate, the ethmoid roof and the skull base at a mean distance of 11.8  4.4, 16.8  4.7 and 13.2  4.2 mm, respectively. However, statistically significant difference between both genders were found in the distances from the nasal floor to the cribriform plate (A), the skull base (C) and the orbital floor (E).

Conclusions : Direct cadaveric measurement in this study confirms the findings results of a previous CT study. Additional result was the statistically significant difference between both genders in the distances from the nasal floor to the cribriform plate (A), to the skull base (C) and to the orbital floor (E).