Endoscopic modified Lothrop procedure: a radiographic anatomic study.

OBJECTIVE Radiographic frontal recess and sinus anatomic measurements were obtained to evaluate the feasibility of the endoscopic modified Lothrop procedure. STUDY DESIGN Computed tomography anatomic study. MATERIALS AND METHODS Computed tomography (CT) scans from 97 patients, 39 male and 58 female, were analyzed in the sagittal plane. Four anatomic parameters were measured 1) midsagittal thickness of the nasal beak, 2) midsagittal distance from nasal beak to skull base, 3) accessible dimension of the frontal recess, and 4) anterior to posterior (AP) dimension of the frontal sinus. RESULTS The average and range of each parameter are as follows: 1) midsagittal nasal beak thickness 0.8 cm (0.3-1.4 cm); 2) midsagittal beak to skull base 1.0 cm (0.4-2.4 cm); 3) left and right accessible dimension 0.8 cm (0.3-1.4 cm) and 0.8 cm (0.4-1.5 cm), respectively; 4) left and right AP diameter of the frontal sinus 1.0 cm (0.3-1.8 cm) and 1.1 cm (0.4-1.9 cm), respectively. There is statistically significant differences between the accessible dimension and AP dimension of the frontal sinus on male and female images. DISCUSSION Preoperative frontal recess and sinus measurements can aid in the selection of patients for the endoscopic modified Lothrop procedure. A significant portion of the population, especially women, had limiting anatomic factors potentially excluding this procedure.