Computed Tomography-Based Evaluation of Foramen Ovale Morphology in Chiari Type 1 Malformation and Trigeminal...

The study aimed to uncover morphologic features of the foramen ovale (FO) in Chiari type 1 malformation (C1M) and trigeminal neuralgia (TN) using computed tomography images.

Radiologic images of 50 adult patients with TN, 50 adult controls, and 50 adult patients with C1M were included in the study.

Chiari type 1 malformation and TN patients had smaller anteroposterior FO diameter compared with controls (P<0.001), and in addition, TN patients had smaller anteroposterior diameter compared with C1M patients (P=0.023). C1M and TN patients had smaller mediolateral FO diameter compared with controls (P<0.001), but TN patients had statistically similar mediolateral diameter compared with C1M patients (P=0.231). The location of FO relative to the lateral pterygoid plate was not affected by C1M or TN (P=0.337). In 3 groups, the most common configuration was the direct type, whereas the less common configuration was the far type. The incidences of the pterygoalar bar (C1M: 8%, TN: 5%, controls: 2%) and pterygospinous bar (C1M: 4%, TN: 4%, controls: 1%) in the study groups displayed that the incidences of the pterygoalar (P=0.150) and pterygospinous (P=0.357) bars were not correlated with C1M or TN.

This study demonstrates that patients with C1M and TN have significantly smaller FO diameters compared with controls. The presence of a narrower FO in C1M may represent a structural predisposition contributing to TN development. These findings provide novel radiologic evidence suggesting a potential anatomic link between C1M and TN.