Objective: This study aimed to determine the values of volumetric and morphological parameters in Chiari malformation type 1 (CM1) patients in the Turkish population.
Methods: This retrospective study was conducted at a single center and included patients diagnosed with CM1 between 2013 and 2023. The patients were separated into two groups: the group CM1 and the control group comprising healthy individuals (group control). The morphometric measurements were clivus length, supraocciput length, foramen magnum diameters, distance between the midbrain-pons junction and midbrain-medullospinal junction, cerebellar hemisphere height, tentorium angle, clivus angle, clivus-tentorium angle, posterior fossa volume (PFV), and cerebellar tonsillar morphology.
Results: The cerebellar tonsillar herniation was 11.43±2.09 mm in group CM1 and -2.64±2.37 mm in the control group. The mean clivus and supraocciput length were 34.26±4.76 mm and 41.26±4.33 mm in group CM1 and 36.85±3.23 mm and 42.21±2.86 mm in the control group, respectively. The mean foramen magnum diameters were 31.41±3.28 mm in group CM1 and 35.64±2.32 mm in the control group (p<0.05). The mean PFV was 153.91±5.02 mL in group CM1 and 180.70±11.62 mL in the control group (p<0.05).
Conclusion: Two parameters were statistically significantly decreased in CM1 patients (PFV and foramen magnum diameters), indicating the main morphometric change that guides diagnosis and treatment in CM1 patients. All other parameters examined in this study were deemed unnecessary because there was no significant difference between CM1 and the average population.