Volumetric Examination of Cerebellum by Automatic Segmentation Method in Individuals with Ankylosing Spondylitis.

Ankylosing spondylitis (AS) is a chronic immune-mediated inflammatory disease primarily affecting the axial skeleton and is frequently associated with postural instability, impaired balance, and altered motor control. The cerebellum plays a central role in sensorimotor integration; however, cerebellar volumetric alterations in AS remain insufficiently elucidated. This study aimed to investigate cerebellar and cerebellar lobular volumetric changes in individuals with AS using a fully automated magnetic resonance imaging (MRI) segmentation method. This retrospective study included 15 patients with AS and 15 age- and sex-matched healthy controls (HC). Brain MRI data were analyzed using the automated CERES pipeline of the volBrain platform. All cerebellar volumetric measures were normalized to intracranial volume (ICV). Group comparisons were performed using appropriate parametric and non-parametric tests, and multiple comparisons were controlled using the false discovery rate (FDR) method. Compared with the control group, nominal differences (p < 0.05) were observed in several cerebellar regions, including Lobule V, Lobule VI, and Lobule VIIIA. Similarly, nominal differences were identified in the gray matter volumes of Lobule I-II and Lobule VIIIA. However, none of these findings remained statistically significant after FDR correction (all q > 0.05). Cerebellar volumetric differences in AS appear to be subtle and do not remain significant after correction for multiple comparisons. These findings suggest that previously reported differences may reflect inter-individual variability rather than robust disease-specific structural alterations. Further studies with larger cohorts and multimodal approaches are warranted.