A morphometric study of the atlanto-occipital joint in adult patients with Chiari malformation type I

Abstract

Background

There are many morphometric studies on Chiari malformation type I (CMI) patients, most of which focus on the posterior cranial fossa (PCF). Less attention has been paid to the atlanto-occipital joint. In this study, we aim to evaluate the morphological characteristics of the atlanto-occipital joint in CMI patients.

Materials and methods

The cervical CT imaging data of adult patients diagnosed with CMI but without any bony malformation in craniovertebral junction (CVJ) who were treated by the authors between January 2014 and December 2019 were retrospectively analyzed. The equal number of sex and age-matched healthy individuals were included as the control group. The morphometric analysis was performed by measuring the length and depth of the atlanto-occipital joint, and the depth/length ratio was calculated to evaluate the curvature of the joint.

Results

A total of 47 patients (15 males and 32 females) were included. The mean age of patients was 47.49 ± 9.01 years (range 19–62 years). The mean depth/length ratio of the atlanto-occipital joint in CMI patients was 0.141 ± 0.065 (range 0.027 − 0.274), which was smaller than that of control individuals (0.228 ± 0.057, range 0.069 − 0.379). And the difference was statistically significant (p < .01).

Conclusions

The atlanto-occipital joints in CMI patients are significantly flatter compared with those in healthy controls. This morphological variation could lead to differences of the atlanto-occipital stability between CMI patients and normal population, which may be related to the pathogenesis of CMI.

Keywords:

• Chiari malformation type I
• morphology
• atlanto-occipital joint
• atlanto-occipital instability
• pathogenesis

Acknowledgments

The authors sincerely thank all the study participants.

Author contributions

XY and HT designed the study. MW and RZ collected the cohort. ZZ and BZ conducted the morphometric analysis. MW conducted the statistical analysis. MW, RZ and HT wrote the manuscript. XY revised the manuscript.

Disclosure statement

The authors report no conflict of interest.

Additional information

Funding

This work was supported by the National Key Research and Development Program of China under Grant No. 2018YFC1002500 and 2019YFC1005100.