Frontal Sinus in Chiari Malformation Type 2: Pneumatization Pattern, Size, and Clinical Importance.

Objective: The examination aimed to compare the morphologic features of the frontal sinus (FS) in patients with Chiari malformation type 2 (CM2) with a control group.

Methods: This retrospective study contained computed tomography images of 45 CM2s and 47 controls. Of 45 CM2 patients aged 11.60±4.60 years, 26 were females and 19 were males. Of 47 controls aged 11.55±4.49 years, 26 were females and 21 were males. The volume, width, depth, and height of FS were bilaterally measured, and its right and left pneumatization patterns (aplasia, hypoplasia, medium, and hyperplasia) were noted.

Results: CM2s had smaller FS width (P=0.004), height (P=0.033), depth (P<0.001), and volume (P<0.001) compared with controls. No statistically significant difference was found between the measurements in terms of sex or side in both groups. Four types related to FS pneumatization patterns were observed in CM2s (aplasia: 16.7%, hypoplasia: 34.4%, medium size: 18.9%, and hyperplasia: 30%) and controls (aplasia: 10.6%, hypoplasia: 9.7%, medium size: 34%, and hyperplasia: 45.7%). This indicated that the FS pneumatization pattern was affected by CM2 (P<0.001).

Conclusions: Patients with CM2 had smaller WFS, HFS, DFS, and VFS compared with controls. The most common type in CM2 was hypoplastic FS, whereas the most common type in controls was hyperplastic FS.