Clinical Significance of Variable Clivus Gradients in Patients with Chiari Malformation Type I After Surgical Decompression: A Retrospective Analysis
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Updated: Feb 3, 2026

Comprehensive Endovascular and Open Surgical Management of Cerebral Arteriovenous Malformations
Published on: October 20, 2017
Xin Wang1, Jun Gao1, Tianyu Wang1
1Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
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.
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