The deficits in sensory pathways caused by peripheral edema, pain, and inflammation of the damaged ligaments may induce maladaptive changes within the central nervous system. The purpose of this study was to determine whether patients with lateral ankle instability (LAI) exhibit morphological differences of brain grey matter when compared with healthy controls, and then assess the relationships between the observed differences and the characteristics of patients.

Cross-sectional.

Thirty patients with LAI and 32 healthy controls without LAI underwent MRI scans using anatomical T1 sequences. A voxel-wise general linear model was used to compare the grey matter volume throughout the whole brain between patients and controls. Linear regression analyses were performed for the gray matter volume within the significant clusters to assess their relationship with age, sex, the existence of acute injury, pain level, sports activity level, and the duration of LAI within the patient group.

The grey matter volume of a cluster within the cerebellar vermis (Vermis_4_5 in automated anatomical labeling template) was significantly reduced in patients with LAI (Gaussian Random Field corrections with two-tailed p-cluster<0.05 and p-voxel<0.001). Multivariate linear regression analysis revealed that the duration of LAI tended to be passively associated with the gray matter volume of this LAI-related vermal cluster (p=0.092).

Participants with LAI exhibited a reduced grey matter volume of a cluster within the cerebellar vermis compared with participants without LAI, and the degree of volume reduction tended to be positively associated with the duration of LAI.