Vidian Canal in Chiari Type I Malformation: A Computed Tomography Study

Objective: To evaluate the position and dimension of the Vidian canal (VC) in Chiari type I malformation (CIM).

Materials and methods: Radiologic views of 49 CIM (mean age: 23.58±15.62 y, sex: 23 males/26 females) and 51 healthy subjects (mean age: 42.50±20.12 y, sex: 21 males/30 females) were included in this computed tomography study.

Results: In comparison with controls, the VC angle and the distance of the round foramen to VC were greater in CIM, but VC length and the distances of the superior wall of the bony sphenoidal sinus, midsagittal plane, and vomerine crest to VC were smaller in CIM. Relative to the sphenoid bone, the position of VC in CIM was determined as type 1 (59.2%) >type 2 (28.6%) >type 3 (12.2%), whereas in controls as type 1 (54.9%) >type 3 (25.5%) >type 2 (19.6%). Relative to the medial pterygoid plate, the position of VC in CIM was determined as type A (63.3%) >type B (20.4%) >type C (16.3%), while in controls as type B (43.1%) >type A (40.2%) >type C (16.7%).

Conclusion: VC size and position correlated with CIM. Compared with controls, CIM patients had more partially protruded VC into the bony sphenoidal sinus and more medially located VC according to the medial pterygoid plate.