Is Basilar Invagination Related with Stenosis of the Hypoglossal Nerve Canal?

To analyze the association between basilar invagination (BI) and stenosis in the hypoglossal canal (HC).

A case-control study with magnetic resonance images (MRIs) of the head from a local database was performed. The study used MRIs of 31 patients with BI (type B) and 36 controls, both groups over 18 years of age and without sex distinction. The internal (ID) and external (ED) diameters of the HC were measured on the coronal plane using the Osirix in its free version 3.9.2 (Mac-Apple platform). We used the Kolmogorov-Smirnov test (with Lilliefors adjustment) to evaluate the normality of the variables, the Levine test to verify the homogeneity of the variances, and Student's t test to verify differences between groups. All analyses were within the 95% confidence interval.

Control group presented right and left ED values of 4.7 ± 0.8 mm and 4.6 ± 0.9 mm, respectively, while the right and left ID showed 4.4 ± 0.9 mm and 4.3 ± 0.8 mm, respectively. The group with BI showed right and left ED values of 3.3 ± 0.9 mm and 3.1 ± 0.9 mm, and the right and left ID had values of 2.8 ± 0.7 mm and 2.7 ± 0.7 mm, respectively. Both ED and ID were smaller in the group with BI (P < 0.001).

Patients with BI of type B presented the narrowing of HC when compared with control participants.