Foramen Magnum Angle: A New Parameter for Basilar Invagination of Type B

• Published in: World neurosurgery Vol. 152; pp. 121 - 123
• Main Authors: Nascimento, José J.C., Silva, Leandro M., Ribeiro, Elayne C.O., Neto, Eulâmpio J.S., Araújo-Neto, Severino A., Diniz, Paula R.B.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-08-2021
• Subjects: Basilar invagination; Cephalometry; Foramen magnum; ROC curve; Basilar invagination; MRI; BI; ROC; Foramen magnum; Cephalometry; ROC curve; FMA
• ISSN: 1878-8750; 1878-8769
• DOI: 10.1016/j.wneu.2021.06.028

To describe the foramen magnum angle (FMA) as a new parameter for basilar invagination (BI) type B.
The FMA was performed on sagittal slice of magnetic resonance imaging (MRI) as a line from the hard palate to the opisthion (angle vertex), and another line from the opisthion to the basion. The MRIs from 31 participants with BI type B and 96 controls were used. Intraclass correlation coefficient, descriptive data, and receiver operating characteristic (ROC) curve were used for statistical analysis at the 95% confidence interval.
The interobserver agreement of the FMA was 0.952. Patients with BI type B had a FMA significantly greater (25.9° ± 9.3°) than control participants (11.6° ± 4.9°) (P < 0.001). The area under the ROC curve showed a diagnostic value of 0.947. The FMA showed sensitivity 0.900 and specificity 0.854 for the cutoff criterion 17° (P < 0.001).
The FMA had an optimal diagnostic value that provided complementary evidence to investigate BI type B.