Background/aim In this study, we aimed to evaluate whether morphological changes in the mesencephalon which were previously described as a diagnostic tool for progressive supranuclear palsy could be associated also with idiopathic normal pressure hydrocephalus. Materials and Methods Consecutive 52 patients with a possible diagnosis of idiopathic normal pressure hydrocephalus (32 female, mean age 73.6 years) and 40 controls (23 female, mean age 72.7 years) with similar demographic characteristics were included the study. The morphologic changes in mesencephalon; hummingbird sign and the vascular compression to mesencephalon were noted. Besides three independent observers evaluated the imaging parameters for idiopathic normal pressure hydrocephalus in Magnetic Resonance Imaging. Inter-observer reliabilities for qualitative and quantitative data were assessed using the Cronbach's Alpha and Intra Class Correlation Coefficient. The correlation of the imaging parameters with each other was evaluated with Pearson correlation. Results Hummingbird sign was found to be significantly more common among patients with idiopathic normal pressure hydrocephalus (p
