MATERIAL and METHODS: We included patients who underwent surgical treatment for Chiari 1 malformation with unknown etiology between 2013-2018 in the Neuosurgery Clinic of Eskişehir Osmangazi University. Morphometric and volumetric measurements of the posterior fossa from cranial and cervical radiological imagings of patients with Chiari 1 malformation were performed by a single experienced observer. The results were independently reviewed by two experienced observers who supervised the process and verified the calculations.

RESULTS: It was observed that basal angle was greater in the group of patients with Chiari 1 malformation (125.29° ± 9.522° Vs. 112.33° ± 9.09°), and a significant difference was observed (p=0.000). In patient group, it was also found that the basion-dens distance (3.51 mm ± 1.695mm Vs. 5.27 ± 1.695 mm) (p=0.000), and cerebellar hemispher height were shorter (58.47 ± 5.143 mm Vs. 52.05 ± 5,008 mm) (p=0.000). Tentorium angle was greater in the patient group (97.95° ± 11.321° vs. 87.79° ± 9.891°) (p=0.034). In patient group, dens height was found to be longer (13.9 ± 2.46 mm vs. 14.79 ± 1.631mm) (p=0.041). Sella volume was found to be smaller (41.4 mm³ Vs. 53.3 mm³) in the patient group compared to the control group (p=0.034), and foramen magnum plane was larger (64.6° vs. 31.1°) (p=0.000).

CONCLUSION: It is concluded that many parameters including BA, FMP, BDD, CHH, TA, DH, and cellar volume are abnormal, suggesting the need for focussing to the hormonal metabolism - related synchondral changes. Keywords : Cellar volume, Chiari malformation, Morphometric measurements