Effect of Ageing on Midbrain to Pons Area Ratio Using MRI: A Cross-sectional Study

Introduction: There is brainstem atrophy with normal ageing. It is pertinent to determine, if this atrophy with ageing, is associated with significant alteration in the midbrain to pons ratio. Aim: To determine sizes and ratio of midbrain and pons area among adults and elderly. Materials and Methods: A cross-sectional, analytical study was done in a tertiary care hospital, S Nijalingappa Medical College, Bagalkot, Karnataka, India from January 2022 to March 2022, including 200 apparently healthy adult and elderly participants. They were divided into two groups, 100 men (M1≤50 years and M2>50 years) and 100 women (F1≤50 years and F2>50 years). Each underwent multiplanar T1 Magnetic Resonance Imaging (MRI) of the brain. An experienced Radiologist identified midsagittal image, and measured midbrain and pons areas on that image. Mean and standard deviations of midbrain and pons area and midbrain to pons area ratio were estimated for each of the groups. Independent Sample t-test was used to determine significance of differences between groups. Results: A total of 200 participants were included in the study with mean age of 51 years and 3 months. The midbrain to pons area ratio among M2 and F2 groups ranged from 0.20 to 0.39, and in M1 and F1 groups it ranged from 0.23 to 0.47. Midbrain areas and midbrain to pons area ratio were significantly more among participants aged less than 50 years among both males (p-value = 0.014 and 0.024) and females (p-value = 0.011 and 0.032) in comparison with participants aged more than 50 years. Conclusion: Midbrain to pons area ratio decreases significantly in older age, and hence, age needs to be accounted for, while interpreting the ratio.