Clinical Significance of Variable Clivus Gradients in Patients with Chiari Malformation Type I After Surgical Decompression: A Retrospective Analysis.

OBJECTIVE: Previous studies have shown that the clivus angle gradient is significantly decreased in patients with Chiari malformation type I (CMI) with an associated syrinx compared with patients with CMI only and a healthy population. To date, the relationship between the clivus gradient and clinical outcomes has remained unclear. The objective of the present study was to investigate whether different clivus gradients (∠α) in CMI after posterior fossa decompression will lead to different clinical outcomes.

METHODS: A total of 86 patients who had undergone surgical decompression at our institution from 2010 to 2016 were retrospectively divided into 2 groups: group A, with a gradient angle >44°, and group B, with an angle ≤44°. The patients' outcomes were determined using the Chicago Chiari Outcome Scale (CCOS).

RESULTS: Direct comparisons were made between the 2 groups. No statistically significant differences were found between the 2 groups in demographic data, preoperative symptoms, postoperative complications, or radiographic characteristics (P > 0.05), except for the length of the postoperative hospital stay (P = 0.006). The mean overall CCOS score was 12.80 ± 2.08. The total CCOS score was significantly different statistically between the 2 groups (P < 0.05). Moreover, group A demonstrated significantly better postoperative improvements compared with group B in the clinical outcome measures using the CCOS (P = 0.021).

CONCLUSIONS: A direct comparison between the 2 groups revealed that a decreased clivus gradient was related to unsatisfactory clinical outcomes. Thus, clivus gradients might emerge as a predictor of clinical outcomes after surgical decompression in patients with CMI.