Evaluation of Craniometric Parameters and Efficacy of Posterior Surgical Intervention Types in Basilar Invagination Patients

Abstract

Objective: Basilar invagination is one of the most frequently observed abnormalities at the craniovertebral junction, in which the odontoid process of C2 prolapses into the foramen magnum.

Methods: The current study included 27 patients who underwent surgery for basilar invagination between October 2013 and January 2023. The study group was divided into 2 groups according to basilar invagination types; type I (the presence of type A atlantoaxial instability and instability is the main pathology) and type II (the presence of type B and C atlantoaxial instability and skull base dysgenesis is the main pathology). Craniometric parameters included in the study were atlantodental interval, posterior atlantodental interval, Chamberlain's line violation, clivus-canal angle, Welcher's basal angle, and Boogaard angle.

Results: The mean age of the patients was 24.30 ± 14.36 years (5-57 years). Fourteen patients (51.9%) were female, and 13 patients (48.1%) were male. Ten patients (37%) had type I basilar invagination, and 17 patients (63%) had type II basilar invagination. Preoperative and postoperative atlantodental interval and Boogaard angle were significantly higher in type I basilar invagination, as preoperative and postoperative posterior atlantodental interval and clivus-canal angle were significantly higher in type II basilar invagination. There was a positive strong correlation between Chamberlain's line violation and Boogaard angle. Postoperative Chamberlain's line violation was significantly higher in occipitocervical fixation (P = 0.035). C1 lateral mass screw fixation was found more successful in Chamberlain's line violation correction than occipital plates. Occipitocervical fixation was found to be associated with higher postoperative Nurick scores (P = 0.015) and complication rates (P = 0.020). Cages applied to the C1-C2 joint space were found to be associated with higher fusion rates (P = 0.023) and lower complication rates (P = 0.024).

Conclusions: In the present study, it was found that C1-C2 fixation was more successful in correcting craniometric parameters and had lower complication rates than occipitocervical fixation. In appropriate patients, it was determined that cage application increased the success rates of the operations.

Keywords: Basilar invagination; C1-C2 fixation; C1-C2 joint cage; Craniometric parameters; Occipitocervical fixation.