Radioanatomical Assessment of the Sphenoid Ridge in Chiari Type I Malformation.

Aim: To compare the sphenoid ridge (SR) morphology in patients with Chiari type I malformation (CIM) with healthy subjects.

Material and methods: Three dimensional (3D) computed tomography scans of 49 (25 men / 24 women) CIM patients aged 45.84±18.04 years, and 52 (26 men / 26 women) healthy subjects aged 43.46±11.62 years were included in the investigation. The angulation and dimension of SR were measured for both groups.

Results: Compared with the controls, CIM patients had greater lesser wing (LW) length (p < 0.001) and LW width in the midline (p < 0.001), but shorter LW width in the midpoint (p=0.001), LW width in the lateral point (p < 0.001), and LW angle (p < 0.001). In CIM, two configurations regarding LW angle types were observed: Type B in 75 LWs (76.5%) and Type C in 23 LWs (23.5%). In controls, two configurations regarding LW angle types were observed: Type A in 35 LWs (33.7%) and Type B in 69 LWs (66.3%). The distribution of the types according to study groups demonstrated that CIM affected significantly LW angle types (p < 0.001).

Conclusion: LW angle and length may represent middle fossa depth and anterior fossa width, respectively; thus, CIM subjects possess shallow middle fossa and wider anterior fossa.